ALBERT

Notes: This article broadly positions the successful establishment of the field of French tropical geography in the immediate postwar period against developments stemming from a longer history of French colonial engagement in Africa, Asia and South America, and clarifies the seemingly late timing of, and paradoxes involved in, the creation of a body of French scientific knowledge about the tropics. Colonial scientific research did not develop in France until the end of the nineteenth century. However, the colonial geography appearing at this time did not rely on fieldwork but, rather, catered to the demands of the business class for overseas expansion and to public curiosity. Even while the medical geography of tropical areas and knowledge of tropical soils and ecology progressed greatly between 1900 and 1940, there were still only a few French geographers working in the tropics. With the advent of the Second World War, when “big science” appeared in France and its colonial empire, the number of French geographers involved in tropical research grew rapidly. The field of tropical geography built up by Pierre Gourou was a synthesis of approaches developed in South America, Africa and Indochina. Although it soon came under strong criticism for its pessimistic view of prospects for industrialisation and urbanisation in the tropics, it seduced French geographers because it matched the contemporary interest in zonality and relied on a genre de vie analysis of, typically, rural areas. Thus, the postwar blossoming of tropical geography shaped by Gourou was more a response to various internal dynamics within French geography than an exercise in imperialism. Its demise was not due to the eclipse of French colonialism but, rather, its inability to deal with the modernisation of tropical societies.

Notes: This paper discusses four key phases in the study of the tropical milieu of monsoon Asia by French geographers and colonial actors over the last 150 years. First, it sees how the natural milieu initially occupied a central and determining place in French colonial and scientific assessments of Indochina, and how the notion of monsoon Asia appeared within the framework of an academic geography (and formatively in the two regional theses produced by Charles Robequain and Pierre Gourou). It then shows how, after the Second World War, francophone geographers developed a “tropicalist” approach to monsoon Asia, one that was inextricably linked with the culturalist approach that was pioneered by Gourou, which later evolved into new, model-building and interdisciplinary approaches to the study of tropical systems. It argues that these successive phases have marked a shift from a centred tropicality - a system of knowledge anchored in French colonialism and centring on debate about the determinist influence of the natural milieu - to a decentred tropicality that rejects environmental determinism, questions the ethnocentric character of tropical geography and integrates the study of tropical geography into the wider social sciences. The paper concludes with the suggestion that tropicality has had an epistemologically stronger and more institutionalised relationship with francophone geography than was the case in anglophone geography.

Notes: In important respects, the disciplinary field of “tropical geography” is a uniquely French field of study, and Pierre Gourou is conventionally seen as its founder and doyen. Yet Gourou did not see himself as the creator of a new paradigm or research school, and geographers were generally more influenced by his writings than by his teaching or any personal connection. With particular reference to French geographical research in and on tropical Africa during the second half of the twentieth century, it is suggested that the development of tropical geography as a subfield - and tropicalism as a research orientation - can be put down to a variety of factors and circumstances. Geographical research on Africa was pivotal, as was the rise to prominence in French research institutes of some of Gourou's disciples. But African academics also played a part, as did criticism of tropical geography for its marginalisation of issues of development and geopolitics. The paper examines this postwar intellectual history and attempts to draw from it a positive and forward looking legacy - a reinvigorated and interdisciplinary “tropicalism”, the main axis of which would be the analysis of the specific characteristics of tropical ecology, and its use and transformation by the societies that live from it. Such a project may help us to confront the contemporary world ecological crisis, and forge critical research projects on globalisation (altermondialisme) that can discern and deal with the complex local-global, and rural-urban, articulations of this phenomenon.

Notes: This article discusses the relevance of the work of Pierre Gourou for Vietnamese and non-Vietnamese scholarship on colonial and postcolonial rural society in Vietnam. The term “tropicality” is used to situate Gourou's work within the framework of both French and Vietnamese regimes of truth. It is argued that Gourou was aware of the complex human geographies of the tropics and monsoon Asia and the challenges this posed to both Western and “tropical” peoples. Gourou and the issue of tropicality is used to show that Vietnamese scholars did not completely reject French colonial systems of knowledge, and that decolonisation did not herald a complete shift in knowledge about rural Vietnam. Rather, since the 1940s there has been antagonism and accommodation between colonial and postcolonial, French and Vietnamese modes of knowledge production. While Gourou underscored the otherness of the tropics, and there are colonial overtones in his work, he had an immense influence on indigenous ethnography and geography in Vietnam and elsewhere in the formerly colonised world. The article traces this important influence and how it has been both questioned and affirmed since independence in the Vietnamese context. It is suggested that the humanistic approach that Gourou pioneered in his 1936 study of the Red River Delta of northern Vietnam has outlived and been able to overcome the setbacks and drawbacks of both colonial and revolutionary/Vietnamese politico-intellectual projects.

Notes: The paper examines how land and forest management policies were elaborated in French Indochina circa 1900–40. It places their development in the context of a scientific and economic discourse about the value of land and forest resources, the most appropriate ways in which they might be exploited and the relationship between colonial science and indigenous knowledge. By focusing on debates and laws relating to the development of small-scale and plantation farming systems (Land Code legislations) and forest management and exploitation (Forest Code legislations) the paper seeks to ground arguments about Western conceptions of the “tropics” within a discussion of national policy development and impacts. Focusing primarily on Cochinchina and Annam (southern and central Vietnam) and drawing on materials from French archives, the paper shows how changes in both attitudes and legislation have had lasting consequences on systems of property rights in forest management and on the place and status of indigenous peoples in Indochina.

Notes: Books reviewed in this article: ‘Letting Them Die’: Why HIV/AIDS Prevention Programmes Fail. Catherine Campbell Red Hills: Migrants and the State in the Highlands of Vietnam. Andrew Hardy Sri Lankan Society in an Era of Globalization: Struggling to Create a New Social Order. S.H. Hasbullah and Barrie M. Morrison (eds.) Female Labour Migration in Southeast Asia: Change and Continuity. Christina Wille and Basia Passl (eds.) Unauthorized Migration in Southeast Asia. Graziano Battistella and Maruja M.B. Asis (eds.)

Notes: Despite recent interest in sacred (fetish) groves as remnant forests, few studies have investigated their sustainability and conservation role in West Africa. This article employs a Geographical Information Systems (GIS) analysis of time series images (1960-98), comprehensive social surveys and ecological field methods to evaluate four sacred groves and eight unprotected tree stands in the coastal savanna of Ghana and compare these with vegetation in the distant forested hinterland. There were strong similarities and substantial differences in tree species between different sacred groves, and between these and the unprotected stands and proximate deciduous forests. In addition, far fewer tree losses were documented in the sacred groves than in the local unprotected stands. Although these sacred groves were on average only partially representative of deciduous forest vegetation, their stronger sustainability compared with unprotected tree stands may be important to consider in detail for conservation.

Notes: This paper aims to examine how seafarers from the Pacific Republic of Kiribati cope with the experience of working with crews of different nationalities, and, further, how the exposure to different cultures during their journeys through international waters influences both their own identity as well as their perceptions of I-Kiribati culture. Based on examples from open and semi-structured interviews with seafarers working on German merchant ships and Japanese fishing vessels, the paper questions the application of concepts of “hybridity” in the case of these I-Kiribati men in favour of the idea of “cultural flexibility”. It further considers to what degree seafarers strongly rooted in the clearly confined cultural values of Kiribati have adapted the values received through their training and employment by German or Japanese and Korean companies and officers. The paper adds to the framework of transnationalism by advancing the notion of emporion, in which the circular and transversal journeys of seafarers are viewed as a connecting space between land-based areas; a space which provides a basis for an extended knowledge and understanding of different cultural outlooks as well as relations between nations.

Notes: This paper focuses on the large-scale land use and land cover changes that have taken place in Sarawak state, East Malaysia over the three decades of 1972-2002. Results are presented from a detailed land use and cover change (LUCC) study in the Niah River catchment using satellite imagery, questionnaire surveys and interviews. Successive waves of land cover changes have taken place. Large forest areas have been logged and gradually replaced by oil palm plantations, which now occupy more than 40 per cent of the total land area in the catchment. Concurrently, small-scale farming systems have also changed. Formerly dominant Iban shifting cultivation practices are increasingly being replaced by cash crop production on permanent fields and impacted by off-farm activities involving many ethnic groups. It is argued that land cover changes are continuous and complex processes involving a large number of variables which can be analysed for different time periods at various scales.

Notes: This paper adopts ideas from critical geopolitics to explore how Western human rights discourses have been enabled and used to construct Myanmar by Australian governments and nongovernmental aid organisations. Three distinct human rights scripts are observed that position donors as either punishers, saviours or partners. It is argued that the scripts are enabled by factors external to the actual abuses themselves, including the traditional scripting of Burma within Australian geopolitical memories; the feminine Burmese identity and the networks embodied by the opposition leader, Daw Suu Kyi; and Australia's shifting geopolitical interests in the Southeast Asia region. The case study is used to argue for a broader geography of human rights that recognises their spatiality. Such geographies can improve and broaden human rights politics and debates beyond state-based campaigning, ensuring that campaigns are in the interests of the most marginalised, rather than the most vocal.

Notes: It has been posited that small-scale industry – businesses with less than 30 workers – provides a large share of employment and income in Ghana. This paper examines the proposition that while such enterprises in the informal sector are said to act as a sponge to soak up surplus labour in marginal activities, they are unprofitable. Using data from a survey in 1998 of 175 micro and small-scale enterprises in the Central Region of Ghana, the paper also confirms problematic aspects of employment in this sector including the lack of formal contracts, irregular pay, low remuneration, non-existent social protection and only marginal employment growth. The implication is that the small-scale industry sector is not economically sustainable in its present form in Ghana.

Notes: Advocacy of the advantages accruing to business clusters in developing economies has followed that in developed economies. With doubts emerging about the evidence for these in developed economies, it is therefore appropriate to review the experience in the developing world. A model of cluster emergence and growth has guided accounts of developing country clusters. Drawing on experience from Indonesia, doubts are raised about that model's prediction of the emergence of successful joint action in maintaining cluster advantages. Any advantages from clustering are insufficient to face development challenges arising from the globalisation of economic activity. The significance of business clusters in low income economies needs to be reviewed in the light of actual experience and the reappraisal emerging in developed or high income countries.

Notes: Book reviewed in this article: Romance on a Global Stage: Pen Pals, Virtual Ethnography, and “Mail Order” Marriages. Nicole Constable The Globalization of Nothing. George Ritzer Southeast Asia Transformed: A Geography of Change. Chia Lin Sien (ed.) Indonesian Sea Nomads. Money, Magic and Fear of the Orang Suku Laut. Cynthia Chou Indonesia's Small Entrepreneurs: Trading on the Margins. Sarah Turner

Notes: The EPIC (Erosion Productivity Impact Calculator) crop model, developed by scientists of the United States Department of Agriculture (USDA), has been successfully applied to the study of erosion, water pollution, crop growth and production in the US but is yet to be introduced for serious research purposes in other countries or regions. This paper reports on the applicability of the EPIC 8120 crop model for the assessment of the potential impacts of climate variability and climate change on crop productivity in sub-Saharan West Africa, using Nigeria as the case study. Among the crops whose productivity has been successfully simulated with this model are five of West Africa's staple food crops: maize, millet, sorghum (guinea corn), rice and cassava. Thus, using the model, the sensitivities of maize, sorghum and millet to seasonal rainfall were demonstrated with coefficients of correlation significant at over 98 per cent confidence limits. The validation tests were based on a comparison of the observed and the model-generated yields of rice and maize. The main problems of validation relate to the multiplicity of crop varieties with contrasting performances under similar field conditions. There are also the difficulties in representing micro-environments in the model. Thus, some gaps appear between the observed and the simulated yields, arising from data or model deficiencies, or both. Based on the results of the sensitivity and validation tests, the EPIC crop model could be satisfactorily employed in assessing the impacts of and adaptations to climate variability and climate change. Its use for the estimation of production and the assessment of vulnerabilities need to be pursued with further field surveys and field experimentation.

Notes: Data collected on rainfall events covering one wet season in Ilorin, Kwara State, Nigeria, were found to be highly correlated with the rate of erosion on all the representative land surface types found in the city – namely bare land, fallow land, short grass and tall tree cover. Of all the rainfall components, rainfall total was best at predicting the rate of soil erosion on all these surfaces. In addition, the study found that a significant constituent of all surfaces, silt which fell through seiver grades 1.18 mm did not cohere, therefore increasing the rate of erosion. However, when grass cover (regenerating with the rains) was at least 95 per cent, erosion was well controlled. Therefore, grass coverage before the onset of the wet season is recommended as an efficient and simple measure to manage erosion in this typical developing urban centre in Nigeria.

Notes: Rural-urban classification constitutes an important framework for the collection and compilation of population data in many countries. While “urban” is often specifically defined, “rural” is treated simply as a residual category. The criteria defining urban also differ from country to country. This paper argues that these rural and urban statistical categories are also highly significant for local governance, increasingly so in recent years given the emphasis on local governance and its restructuring. In India, constitutional amendments have given constitutional status to local bodies in the federal structure of the country. Local bodies are thus now expected to draw up their own plans and initiate development works, which requires them to generate their own resources and lessen their dependence on central government funding. It is thus necessary to reorganize urban space into viable spatial units in terms of their revenue base. While rural-urban classification is the task of the Census of India, state governments are responsible for granting municipal status to urban centres. This paper examines the criteria and limitations of the rural-urban classification followed by the Census, its congruence with the dynamics of state-accorded municipal/non-municipal status and some implications for municipal governance in India.

Notes: This paper explores the activities and problems of indigenous women's organisations in Ghana. The survey data that form the basis of the analysis were collected in 1998 from a sample of 66 women's organisations in the districts of Atebubu and Techiman of Brong Ahafo Region in Ghana. The results suggest that despite the debilitating impacts of patriarchy, poverty and illiteracy, the women in both districts have managed to use their grassroots organisations to improve the socioeconomic circumstances of their members in particular and their communities in general. Given the dearth of theoretical and empirical analyses on grassroots mobilisation of women in sub-Saharan Africa, the results presented here are intended to stimulate further research and discussion on the subject.

Notes: Using a general statistical model, this study attempts to characterise the trend of deforestation in the northeast region (Isan) of Thailand between 1975 and 1991, a period when the kingdom had sustained high rates of economic growth and steady increases in population. Using data obtained directly from government bodies on the 17 provinces comprising this heavily deforested region, the study examines the correlations between forest area and a set of six variables: population density, agricultural area, real per capita income, accumulated irrigated area, agricultural credit levels, and distance from Bangkok, the national political and economic centre. It also considers the effect of the two logging bans instituted in 1979 and since 1989. The study found a negative correlation between forest area and population density in particular, followed in ranking by agricultural credit, per capita income, the logging bans and distance from Bangkok. Viewed together with more recent data showing that rates of deforestation in the kingdom as a whole have slowed and appear to be stabilising, these results also suggest the beginnings in the 1990s of a forest transition – from an industrial to a post-industrial stage in forest utilisation – in Thailand.

Notes: Observation data of temperature, precipitation and snow depth have been compiled and generalized climatologically for a network of 38 stations in and around the Barents and Kara seas, for the period 1951–1992. The monthly precipitation totals were corrected for measuring errors, and the correction method is described in detail. The corrected precipitation values show that the annual precipitation in the region ranges from more than 500 mm along the coast of the Kola Peninsula to less than 200 mm in parts of the north-eastern Kara Sea. The solid fraction of the annual precipitation ranges from 70% in northern parts to 35% in southern parts. For the period 1951–1992 the analysis indicates decreasing trends in annual values of temperature, precipitation and snow depths in the north-eastern parts of the region.

Notes: The importance of the Hell Gate Polynya to marine birds in High Arctic Canada has not been assessed for two decades. Our breeding season surveys in 2002–04 found 19 species of marine birds using the polynya, in annual numbers perhaps reaching 25000 individuals. The site appears to support nationally significant populations of northern fulmar (Fulmarus glacialis), Thayer's gull (Larus thayeri) and High Arctic brant (Branta bernida hrota), as well as locally important numbers of other species including common eiders (Somateria mollissima borealis) and black guillemots (Cepphus grylle). The polynya may be particularly important for migration, as many species are observed here earlier than elsewhere in the High Arctic.

Notes: Information about the spatial variations of snow properties and of annual accumulation on ice sheets is important if we are to understand the results obtained from ice cores, satellite remote sensing data and changes in climate patterns. The layer structure and spatial variations of physical properties of surface snow in western Dronning Maud Land were analysed during the austral summers 1999/2000, 2000/01 and 2003/04 in five different snow zones. The measurements were performed in shallow (1–2 m) snow pits along a transect extending 350 km from the seaward edge of the ice shelf to the polar plateau. These pits covered at least the last annual accumulation and ranged in elevation from near sea level to 2500 m a.s.l. The Ø18O values and accumulation rates had a good linear correlation with the distance from the coast. The mean accumulation on the ice shelf was 312±28 mm water equivalent (w.e.); in the coastal region it was 215±43 mm w.e. and on the polar plateau it was 92±25 mm w.e. The mean annual conductivity and grain size values decreased exponentially with increasing distance from the ice edge, by 48%/100 km and 18%/100 km respectively. The mean grain size varied between 1.5 and 1.8 mm. Depth hoar layers were a common phenomenon, especially under thin ice crusts, and were associated with low dielectric constant values.

Notes: To examine algae populations, three expeditions (in March 2001, April 2002 and February 2003) were conducted in the Guba Chupa (Chupa Estuary; north-western White Sea), and one cruise was carried out in the open part of the White Sea in April 2003 and in the northern part of the Barents Sea in July 2001. Sea ice algae and phytoplankton composition and abundance and the content of sediment traps under the land-fast ice in the White Sea and annual and multi-year pack ice in the Barents Sea were investigated. The community in land-fast sea ice was dominated by pennate diatoms and its composition was more closely related to that of the underlying sediments than was the community of the pack ice, which was dominated by flagellates, dinoflagellates and centric diatoms. Algae were far more abundant in land-fast ice: motile benthic and ice-benthic species found favourable conditions in the ice. The pack ice community was more closely related to that of the surrounding water. It originated from plankton incorporation during sea ice formation and during seawater flood events. An additional source for ice colonization may be multi-year ice. Algae may be released from the ice during brine drainage or sea ice melting. Many sea ice algae developed spores before the ice melt. These algae were observed in the above-bottom sediment traps all year around. Three possible fates of ice algae can be distinguished: 1) suspension in the water column, 2) sinking to the bottom and 3) ingestion by herbivores in the ice, at the ice-water interface or in the water column.

Notes: Icing fields are common in Svalbard and very diverse with respect to shape. The occurrence and spatial structure of icing fields in front of glaciers were analysed using aerial photographs (at a scale of 1:50000) taken from 19 July to 25 August 1990–a unique set of images covering the whole archipelago in one summer season. Icing fields were observed in front of 217 glaciers. A total area of 12.3 km2 appeared to be covered by the icings. This value, from late in the ablation season, is likely to be near the seasonal minimum. Of the 217 glaciers, 192 were selected for further analysis, carried out by stereoscopic observation of the aerial photographs. Striking difference in brightness of the icing fields in comparison to the surrounded terrain combined with field experience of the geomorphic setting of its occurrence made possible the complete inventory of the icing phenomena for the whole of Svalbard. Morphometric features were measured directly on photographs and on scanned portions of them. Results from field studies of melting and the decrease of the area of icing fields at the front of two glaciers are also presented. The shape and distribution of icings depend on a set of glaciological factors and on the glacial and geomorphologic setting. The duration of frigid temperatures in the winter when the icing fields were formed is also important. Results show that oval and circular shapes are characteristic for icing fields after surviving the ablation season. These fields have an important geomorphological influence on the outwash plains that currently develop in Svalbard.

Notes: The largest sulphuric acid event revealed in an ice core from the Lomonosovfonna ice cap, Svalbard, is associated with the densest concentration of microparticles in the ice core at 66.99 m depth. Electron microscope analysis of a volcanic ash particle shows it has the same chemical composition as reported for debris from the eruption of Iceland's Laki fissure in 1783 and confirms the identification of the tephra. Most of the particles in the deposit are not ash, but are common sand particles carried aloft during the eruption event and deposited relatively nearby and downwind of the long-lasting eruption. The tephra layer was found 10–20 cm deeper than high sulphate concentrations, so it can be inferred that tephra arrived to Lomonosovfonna about 6–12 months earlier than gaseous sulphuric acid precipitation. The sulphuric acid spike has a significant cooling impact recorded in the oxygen isotope profile from the core, which corresponds to a sudden drop in temperature of about 2°C which took several years to recover to previous levels. These data are the first particle analyses of Laki tephra from Svalbard and confirm the identification of the large acidic signal seen in other ice cores from the region. They also confirm the very large impact that this Icelandic eruption, specifically the sulphuric acid rather than ash, had on regional temperatures.

Notes: Seventy-seven years ago a tragedy took place in the Norwegian Arctic which shook the international community–especially Norwegians–and led to the public condemnation of the Italian explorer and airship builder Umberto Nobile. Steinar Aas, historian and author of a book on Nobile, has perused a trove of “new” material recently donated to the Norwegian Polar Institute and the Polar Museum in Tromsø, Norway. In this (unreviewed) piece, Aas explains why he finds the new collection a fascinating subject for further research.

Notes: The development and age of the present geomorphology and superficial material of the Coloradofjella plateau, Spitsbergen, have been investigated through field surveying and laboratory sediment analyses. The focus was specifically on the role of glacial erosion and periglacial processes. The summit plain is deeply incised with large V-shaped valleys. Extensive networks of ice wedge polygons indicate that the fine-grained regolith is at least a few metres thick. An abundance of coarse-grained gabbroid erratics, clearly derived from sources further to the east, are distributed over parts of the summit plain. A vertical-walled dolerite dyke protruding up to 4 m above the adjacent surface shows no sign of glacial erosion. Our findings confirm that the present bedrock geomorphology and regolith in the summit plain survived at least the Late Weichselian glaciation. This is best explained by the ice sheet having been cold-based throughout its existence on the summit plain. Cold-based conditions imply that permafrost survived the last glacial cover. Based on the geomorphic evidence and estimates of Late Cenozoic erosion, we suggest that the present summit plains roughly represent the remains of a preglacial surface.

Notes: Book Review in this ArticleReview of Frozen oceans: the floating world of pack ice, by David N. Thomas

Notes: Inevitably, aerobic life leads to the formation of deleterious reactive oxygen species (ROS) which participate in biomolecule oxidation, hence augmenting biomolecule turnover. Organisms have adapted to counteract the noxious effects of ROS by developing a battery of antioxidant defences (AOX) which comprise enzymes and low-molecular weight scavengers. Past studies have reported elevated AOX levels in polar pectinid bivalves compared with temperate congeners. This finding is controversial as mitochondrial ROS generation is low in polar versus temperate species, and, to date, there is no generally accepted explanation of the causes of increased basal AOX levels in polar waters. We suggest that the low food availability in those ecosystems may result in polar marine ectotherms diverting some energy into the maintenance of high AOX. We tested this hypothesis by comparing the total oxyradical scavenging capacity (peroxyl, hydroxyl and peroxynitrite) of three clam species: Laternula elliptica (Antarctic), Mya truncata (Arctic) and Mya arenaria (temperate). The data confirmed that polar bivalves are characterized by higher AOX. Herein, we propose that high AOX is required in environments characterized by low food availability as AOX efficiently protects biomolecules, notably the RNA expressed at high levels by cold-water ectotherms. Also, high AOX may explain the relatively long lifespan of most polar ectotherms.

Notes: This paper examines the relationships between measurable watershed hydrologic features, base flow recession rates, and the Q7,10 low flow statistic (the annual minimum seven-day average streamflow occurring once every 10 years on average). Base flow recession constants were determined by analyzing hydrograph recession data from 24 small (〉130 km2), unregulated watersheds across five major physiographic provinces of Pennsylvania, providing a highly variable dataset. Geomorphic, hydrogeologic, and land use parameters were determined for each watershed. The base flow recession constant was found to be most strongly correlated to drainage density, geologic index, and ruggedness number (watershed slope); however, these three parameters are intercorrelated. Multiple regression models were developed for predicting the recession rate, and it was found that only two parameters, drainage density and hydrologic soil group, were required to obtain good estimates of the recession constant. Equations were also developed to relate the recession rates to Q7,10 per unit area, and to the Q7,10/Q50 ratio. Using these equations, estimates of base flow recession rates, Q7,10, and streamflow reduction under drought conditions can be made for small, ungaged basins across a wide range of physiography.

Notes: The need for scientifically defensible water quality standards for nonpoint source pollution control continues to be a pressing environmental issue. The probability of impact at differing levels of nonpoint source pollution was determined using the biological response of instream organisms empirically obtained from a statistical survey. A conditional probability analysis was used to calculate a biological threshold of impact as a function of the likelihood of exceeding a given value of pollution metric for a specified geographic area. Uncertainty and natural variability were inherently incorporated into the analysis through the use of data from a probabilistic survey. Data from wadable streams in the mid-Atlantic area of the U.S. were used to demonstrate the approach. Benthic macroinvertebrate community index values (EPT taxa richness) were used to identify impacted stream communities. Percent fines in substrate (silt/clay fraction, 〉 0.06 mm) were used as a surrogate indicator for sedimentation. Thresholds of impact due to sedimentation were identified by three different techniques, and were in the range of 12 to 15 percent fines. These values were consistent with existing literature from laboratory and field studies on the impact of sediments on aquatic life in freshwater streams. All results were different from values determined from current regulatory guidance. Finally, it was illustrated how these thresholds could be used to develop criterion for protection of aquatic life in streams.

Notes: Pebble counts have been used for a variety of monitoring projects and are an important component of stream evaluation efforts throughout the United States. The utility of pebble counts as a monitoring tool is, however, based on the monitoring objectives and the assumption that data are collected with sufficient precision to meet those objectives. Depending upon the objective, sources of variability that can limit the precision of pebble count data include substrate heterogeneity at a site, differences in substrate among sample locations within a stream reach, substrate variability among streams, differences in when the substrate sample is collected, differences in how and where technicians pick up substrate particles, and how consistently technicians measure the intermediate axis of a selected particle. This study found that each of these sources of variability is of sufficient magnitude to affect results of monitoring projects. Therefore, actions such as observer training, increasing the number of pebbles measured, evaluating several riffles within a reach, evaluating permanent sites, and narrowing the time window during which pebble counts are conducted should be considered in order to minimize variability. The failure to account for sources of variability associated with pebble counts within the study design may result in failing to meet monitoring objectives.

Notes: : Patterns of dry season surface flow in forested headwater channels of southwest Washington were observed during August to September 2001 and July to October 2002. In 2001, 17 channels were sampled once, and the uppermost points of continuous flow (CF) and surface water (SW) were located. In 2002, sampling was replicated three to five times at each of 21 channels. Annual and seasonal data suggested that the location of SW varied less than CF. In most channels, SW remained at or near the channel head year around. The pattern of surface flow between CF and the channel head was used to test alternative hypotheses describing dry season recession patterns: (A) surface flow consistently retreats in a downstream direction, and (B) flow comes from fixed sources along the channel, thus surface flow retreats up-channel towards these sources. The dominant surface flow spatial pattern in streams less than 30 percent slope was increased intermittency without a clear pattern of retreat, and thus inconsistent with either hypothesis. High gradient channels (〈 30 percent slope) exhibited a combination of increased intermittency, and extensive upward retreats of surface water consistent with Hypothesis B. Differences between 2001 and 2002 suggest late summer flows in small headwater basins were controlled by spring precipitation, rather than the typically greater winter precipitation.

Notes: : During the fall of 2000, the occurrence was examined of 16 herbicides and 13 herbicide degradates in samples from 55 wells in shallow aquifers underlying grain producing regions of Illinois. Herbicide compounds with concentrations above 0.05 μg/L were detected in 56 percent of the samples. No concentrations exceeded regulatory drinking water standards. The six most frequently detected compounds were degradates. Water age was an important factor in determining vulnerability of ground water to transport of herbicide compounds. Unconsolidated aquifers, which were indicated to generally contain younger ground water than bedrock aquifers, had a higher occurrence of herbicides (73 percent of samples) than bedrock aquifers (22 percent). Temporal analysis to determine if changes in concentrations of selected herbicides and degradates could be observed over a near decadal period indicated a decrease in detection frequency (25 to 18 percent) between samplings in 1991 and 2000. Over this period, significant differences in concentrations were observed for atrazine (decrease) and total acetochlor (increase). The increase in acetochlor compound concentrations corresponds to an increase in acetochlor use during the study period, while the decrease in atrazine concentrations corresponds to relatively consistent use of atrazine. Changes in frequency of herbicide detection and concentration do not appear related to changes in land use near sampled wells.

Notes: : Watersheds are widely accepted as a useful geography for organizing natural resource management in Australia and the United States. It is assumed that effective action needs to be underpinned by an understanding of the interactions between people and the environment. While there has been some social research as part of watershed planning, there have been few attempts to integrate socio-economic and biophysical data to improve the efficacy of watershed management. This paper explores that topic. With limited resources for social research, watershed partners in Australia chose to focus on gathering spatially referenced socio-economic data using a mail survey to private landholders that would enable them to identify and refine priority issues, develop and improve communication with private landholders, choose policy options to accomplish watershed targets, and evaluate the achievement of intermediate watershed plan objectives. Experience with seven large watershed projects provides considerable insight about the needs of watershed planners, how to effectively engage them, and how to collect and integrate social data as part of watershed management.

Notes: : Controlling agricultural nonpoint source pollution from livestock grazing is a necessary step to improving the water quality of the nation's streams. The goal of enhanced stream water quality will most likely result from the implementation of an integrated system of best management practices (BMPs) linked with stream hydraulic and geomorphic characteristics. However, a grazing BMP system is often developed with the concept that BMPs will function independently from interactions among controls, climatic regions, and the multifaceted functions exhibited by streams. This paper examines the peer reviewed literature pertaining to grazing BMPs commonly implemented in the southern humid region of the United States to ascertain effects of BMPs on stream water quality. Results indicate that the most extensive BMP research efforts occurred in the western and midwestern U.S. While numerous studies documented the negative impacts of grazing on stream health, few actually examined the success of BMPs for mitigating these effects. Even fewer studies provided the necessary information to enable the reader to determine the efficacy of a comprehensive systems approach integrating multiple BMPs with pre-BMP and post-BMP geomorphic conditions. Perhaps grazing BMP research should begin incorporating geomorphic information about the streams with the goal of achieving sustainable stream water quality.

Notes: : The purpose of this research was to examine through modeling and experimentation if seepage out of a pond through stratified soil can be predicted, and effectively collected and managed to augment streamflow during a low precipitation period extending three months or more. The 55 m2 experimental pond with sandy/loamy banks was excavated to hardpan, and its bottom was approximately 0.7 above the water table. Output from a mathematical model containing both bottom and bank seepage elements agreed with experimental data, and showed that as compared to bottom seepage, the bank seepage contributed approximately 25 percent of the total seepage. Seepage collection (as measured from a circumscribing ditch) linearly varied with stage (r2 〈 0.99). There was an 8 to 22 percent over-collection at the lower pond stages, and a 9 to 45 percent under-collection at the highest stage. As an example of its utility, the model was applied to estimate the pond size and shape needed to supply a hypothetical stream and maintain fish stocks during a three-month low-precipitation period. Future work will focus on nutrient transport and removal.

Notes: : Grouping of nitrate-nitrogen (NO3-N) leaching losses from agricultural fields into spatial clusters can help determine the cause/effect relationships for their occurrence. This study was designed to investigate the spatial relationships of low, medium, and high NO3-N leaching losses clusters with soil and landscape attributes using cluster and discriminant analysis and the map overlay capability of a geographical information system (GIS). Field measured data of a six-year (1993 through 1998) study on NO3-N leaching losses from 36 experimental fields at the Iowa State University's northeastern research center near Nashua, Iowa, were normalized on an annual basis to compare over the years. The cluster analysis resulted in the formation of three clusters based on the satisfactory evaluation criteria of pseudo-F statistic, cubic clustering criterion, and R2 values. The discriminant analysis, carried out on the basis of clusters, identified elevation and subsurface drainage as the factors that contributed significantly (p 〉 0.01) in discriminating among these clusters. The verification of discriminant functions developed on these factors predicted the cluster membership for all the groups with an overall accuracy of 86 percent. The map overlay analyses of GIS showed that spatial occurrence of the clusters transporting high NO3-N leaching losses was affected by the interaction of soil type and elevation levels.

Notes: : The use of glyphosate has increased rapidly, and there is limited understanding of its environmental fate. The objective of this study was to document the occurrence of glyphosate and the transformation product aminomethylphosphonic acid (AMPA) in Midwestern streams and to compare their occurrence with that of more commonly measured herbicides such as acetochlor, atrazine, and metolachlor. Water samples were collected at sites on 51 streams in nine Midwestern states in 2002 during three runoff events: after the application of pre-emergence herbicides, after the application of post-emergence herbicides, and during harvest season. All samples were analyzed for glyphosate and 20 other herbicides using gas chromatography/mass spectrometry or high performance liquid chromatography/mass spectrometry. The frequency of glyphosate and AMPA detection, range of concentrations in runoff samples, and ratios of AMPA to glyphosate concentrations did not vary throughout the growing season as substantially as for other herbicides like atrazine, probably because of different seasonal use patterns. Glyphosate was detected at or above 0.1 μg/1 in 35 percent of pre-emergence, 40 percent of post-emergence, and 31 percent of harvest season samples, with a maximum concentration of 8.7 μg/1. AMPA was detected at or above 0.1 μg/1 in 53 percent of pre-emergence, 83 percent of post-emergence, and 73 percent of harvest season samples, with a maximum concentration of 3.6 μg/1. Glyphosate was not detected at a concentration at or above the U.S. Environmental Protection Agency's maximum contamination level (MCL) of 700 μg/1 in any sample. Atrazine was detected at or above 0.1 μg/1 in 94 percent of pre-emergence, 96 percent of post-emergence, and 57 percent of harvest season samples, with a maximum concentration of 55 μg/1. Atrazine was detected at or above its MCL (3 μg/1) in 57 percent of pre-emergence and 33 percent of post-emergence samples.

Notes: : The performance of two popular watershed scale simulation models — HSPF and SWAT — were evaluated for simulating the hydrology of the 5,568 km2 Iroquois River watershed in Illinois and Indiana. This large, tile drained agricultural watershed provides distinctly different conditions for model comparison in contrast to previous studies. Both models were calibrated for a nine-year period (1987 through 1995) and verified using an independent 15-year period (1972 through 1986) by comparing simulated and observed daily, monthly, and annual streamflow. The characteristics of simulated flows from both models are mostly similar to each other and to observed flows, particularly for the calibration results. SWAT predicts flows slightly better than HSPF for the verification period, with the primary advantage being better simulation of low flows. A noticeable difference in the models' hydrologic simulation relates to the estimation of potential evapotranspiration (PET). Comparatively low PET values provided as input to HSPF from the BASINS 3.0 database may be a factor in HSPF's overestimation of low flows. Another factor affecting baseflow simulation is the presence of tile drains in the watershed. HSPF parameters can be adjusted to indirectly account for the faster subsurface flow associated with tile drains, but there is no specific tile drainage component in HSPF as there is in SWAT. Continued comparative studies such as this, under a variety of hydrologic conditions and watershed scales, provide needed guidance to potential users in model selection and application.

Notes: : A curve number based model, Soil and Water Assessment Tool (SWAT), and a physically based model, Soil Moisture Distribution and Routing (SMDR), were applied in a headwater watershed in Pennsylvania to identify runoff generation areas, as runoff areas have been shown to be critical for phosphorus management. SWAT performed better than SMDR in simulating daily streamflows over the four-year simulation period (Nash-Sutcliffe coefficient: SWAT, 0.62; SMDR, 0.33). Both models varied streamflow simulations seasonally as precipitation and watershed conditions varied. However, levels of agreement between simulated and observed flows were not consistent over seasons. SMDR, a variable source area based model, needs further improvement in model formulations to simulate large peak flows as observed. SWAT simulations matched the majority of observed peak flow events. SMDR overpredicted annual flow volumes, while SWAT underpredicted the same. Neither model routes runoff over the landscape to water bodies, which is critical to surface transport of phosphorus. SMDR representation of the watershed as grids may allow targeted management of phosphorus sources. SWAT representation of fields as hydrologic response units (HRUs) does not allow such targeted management.

Notes: : Although the curve number method of the Natural Resources Conservation Service has been used as the foundation of the hydrology algorithms in many nonpoint source water quality models, there are significant problematic issues with the way it has been implemented and interpreted that are not generally recognized. This usage is based on misconceptions about the meaning of the runoff value that the method computes, which is a likely fundamental cause of uncertainty in subsequent erosion and pollutant loading predictions dependent on this value. As a result, there are some major limitations on the conclusions and decisions about the effects of management practices on water quality that can be supported with current nonpoint source water quality models. They also cannot supply the detailed quantitative and spatial information needed to address emerging issues. A key prerequisite for improving model predictions is to improve the hydrologic algorithms contained within them. The use of the curve number method is still appropriate for flood hydrograph engineering applications, but more physically based algorithms that simulate all streamflow generating processes are needed for nonpoint source water quality modeling. Spatially distributed hydrologic modeling has tremendous potential in achieving this goal.

Notes: : The penetration of sunlight into the water column plays a critical role in the aquatic ecosystem. This study investigates light attenuation through the water column of the Danshuei River estuary and explores the models for quantifying it. The measurement of photosynthetically active radiation (PAR) indicates that the conventional exponential attenuation of light with depth is a very good model. A light attenuation coefficient may be derived from the PAR measurements at each location. The simpler measurements of Secchi depth (SD) provide an approximate estimate of the attenuation coefficients through an inverse linear relationship. The results also reveal that the amount and kinds of materials, which are either dissolved or suspended in the water, control light attenuation through the water column. However, the linear regression with such a model results in very poor correlation, and a relatively large constant term for the Danshuei River estuary. The regression with salinity yields a good correlation, indicating that the fraction of sea water might be a good parameter for estimating light attenuation coefficient for practical application in the Danshuei River estuary.

Notes: : The fate of contaminants in large water bodies is highly influenced by the transfer of flow and solutes across the water sediment interface. In this paper, an analytical model is presented where flow in both sediment bed and open channel is coupled at the interface through a boundary layer occupying the upper part of the sediment bed. The presence of this layer allows not only the capture of the inertia effects through a drag term in the generalized Darcy's equation, but also the specification of different soil parameters for the two porous zones. The flow is advective and driven by wave action along the water surface. The resulting system is solved for the pressure and flux in each sediment layer. The generated transport velocity fields are linked to a random walk simulation that is used to examine the trajectories of solute particles. Comparison of these trajectories against experimental tracer tests suggests a pattern very similar to the one attributed to the presence of surface mounds. The results clearly show the significance of the boundary layer and the drag term for soil with high permeability and the impact of both the thickness of the boundary layer and the length of the gravity wave relative to the depth of the water channel on the transport and exchange across the interface. The paper also examines the sensitivity of the mass exchange to the permeability of the two porous zones.

Notes: : Florida water resources are among the most abundant in the United States, with Florida receiving the second-highest mean annual rainfall of all states. However, water supply issues have troubled the state due to the highly variable spatial and temporal distributions of water supply and demand, and they are aggravated by the population's preference for settling in coastal regions where freshwater resources are scarce. Historically, the competing issues of water resource development and natural systems protection have placed water management agencies and local governments at odds. In 1997, the Florida Legislature enacted several major changes to Florida water law in an attempt to improve water resource planning and protection. This paper briefly reviews the history of water management in Florida with an emphasis on decisions culminating in the 1997 legislation, which requires the development of minimum flows and levels. Also examined is the impact of the 1997 law on water management. Efforts made to comply with legislative mandates are summarized; these include, to date, establishment of minimum flows and levels on 209 water bodies and budgeting in excess of $1.4 billion for water resource development projects.

Notes: : The Hydrologic Simulation Program-FORTRAN (HSPF) is a powerful time variable hydrologic model that has rarely been applied in arid environments. Here, the performance of HSPF in southern California was assessed, testing its ability to predict annual volume, daily average flow, and hourly flow. The model was parameterized with eight land use categories and physical watershed characteristics. It was calibrated using rainfall and measured flow over a five-year period in a predominantly undeveloped watershed and it was validated using a subsequent 4-year period. The process was repeated in a separate, predominantly urbanized watershed over the same time span. Annual volume predictions correlated well with measured flow in both the undeveloped and developed watersheds. Daily flow predictions correlated well with measured flow following rain events, but predictions were poor during extended dry weather periods in the developed watershed. This modeling difficulty during dry-weather periods reflects the large influence of, and the poor accounting in the model for, artificially introduced water from human activities, such as landscape overwatering, that can be important sources of water in urbanized arid environments. Hourly flow predictions mistimed peak flows, reflecting spatial and temporal heterogeneity of rainfall within the watershed. Model correlation increased considerably when predictions were averaged over longer time periods, reaching an asymptote after an 11-hour averaging window.

Notes: : Twenty-three stream sites representing a range of forested, agricultural, and urban land uses were sampled in the South Platte River Basin of Colorado from July through September 2002 to characterize water quality during drought conditions. With a few exceptions, dissolved ammonia, Kjeldahl nitrogen, total phosphorus, and dissolved orthophosphate concentrations were similar to seasonal historical levels in all land use areas during the drought. At some agricultural sites, decreased dilution of irrigation return flow may have contributed to higher concentrations of some nutrient species, increased primary productivity, and higher dissolved oxygen concentrations. At some urban sites, decreased dilution of base flow and wastewater treatment plant effluent may have contributed to higher dissolved nitrite-plus-nitrate concentrations, increased primary productivity, and higher dissolved oxygen concentrations. Total pesticide concentrations in urban and agricultural areas were not consistently higher or lower during the drought. At most forested sites, decreased dilution of ground water-derived calcium bicarbonate type base flow likely led to elevated pH and specific-conductance values. Water temperatures at many of the forested sites also were higher, contributing to lower dissolved oxygen concentrations during the drought.

Notes: : One of the biggest challenges in managing cold water streams in the Midwest is understanding how stream temperature is controlled by the complex interactions among meteorologic processes, channel geometry, and ground water inflow. Inflow of cold ground water, shade provided by riparian vegetation, and channel width are the most important factors controlling summer stream temperatures. A simple screening model was used to quantitatively evaluate the importance of these factors and guide management decisions. The model uses an analytical solution to the heat transport equation to predict steady-state temperature throughout a stream reach. The model matches field data from four streams in southwestern Wisconsin quite well (typically within 1°C) and helps explain the observed warming and cooling trends along each stream reach. The distribution of ground water inflow throughout a stream reach has an important influence on stream temperature, and springs are especially effective at providing thermal refuge for fish. Although simple, this model provides insight into the importance of ground water and the impact different management strategies, such as planting trees to increase shade, may have on summer stream temperature.

Notes: : Three instruments commonly used to measure stream canopy cover were evaluated: the clinometer, a modified spherical convex densiometer Model A, and a hemispherical image system. The hemispherical image system was also used to model shade. At each of five locations throughout Oregon, canopy cover above a stream was measured from the center of the stream along a series of transects. Vegetation along the reaches sampled ranged from a densely vegetated coastal forest stand to a sparsely vegetated eastern Oregon meadow. When techniques were compared within each site, canopy cover measured with the clinometer was similar to that measured with hemispherical imagery. The densiometer measurements, however, were typically lower than, though still highly correlated with, those derived from hemispherical images and from the clinometer. Because of site-specific factors, the differences between all methods were significant in the Willamette and John Day Provinces. Canopy cover and shade were not equivalent for the streams studied.

Notes: : In 1996, the State of Oregon adopted a water quality standard based on Escherichia coli (E. coli), recognizing E. coli as an indicator of pathogenic potential. The Oregon Department of Environmental Quality (DEQ) began analysis for E. coli that same year. The Oregon DEQ continued collection and analysis of fecal coliform (a prior indicator organism) for data input to bacterial loading models and the Oregon Water Quality Index (OWQI). The OWQI is a primary indicator of general water quality for the Oregon DEQ and the Oregon Progress Board. The objective of this study was to develop a regression relationship between fecal coliform and E. coli. This relationship would fill data gaps and extend water quality models and indicators. Water quality policy is better informed by the ability of these extended water quality models to determine whether water quality meets present or would have met past bacterial standards. Monitoring resources spent on dual bacterial analyses could be conserved. This study also showed that changes to OWQI values (as a result of changing bacterial indicators) were minimal, and corresponded to improved characterization of water quality with respect to pathogenic potential.

Notes: : The large volumes of ground water that are discharged from the Everglades toward the Miami metropolitan area have historically posed a significant environmental water supply problem. In order to analyze the effects of seepage barriers on these subsurface outflows, the analytic element modeling code GFLOW was used to construct a ground water flow model of a region that includes a portion of the Everglades along with adjacent developed areas. The hydrology of this region can be characterized by a highly transmissive surficial aquifer in hydraulic contact with wetlands and canals. Calibration of the model to both wet and dry season conditions yielded satisfactory results, and it was concluded that the analytic element method is a suitable technique for modeling ground water flow in the Everglades environment. Finally, the model was used to evaluate the potential effectiveness of a subsurface barrier approximately two miles long for increasing water levels within the adjacent fringes of the Everglades National Park. It was found that the barrier had a negligible effect on water levels due to both its relatively short length and the high transmissivity of the surficial aquifer.

Notes: : Integrated water resources management is important, especially in watersheds where substantial interactions exist between the ground and surface water sources. This management warrants the need for reliable estimates of both an overall basin water budget and hydrologic fluctuations between ground water and surface water sources. The objectives of this study were to estimate the total water budget and to simulate the effects of the management of water in the Big Lost River Basin in Idaho. The study used the FIPR Hydrological Model (FHM), a hydrological model developed by the University of South Florida for the Florida Institute of Phosphate Research (FIPR). The FHM is an integrated model that simulates the full water budget of the surface and ground water systems. It has two public domain components: Hydrological Simulation Program - FORTRAN (HSPF) and Modular Three-Dimensional Finite-Difference Ground Water Flow Model (MODFLOW). This study quantified the hydrologic fluxes between ground water and surface water and determined a comprehensive and accurate water budget for the Big Lost River. The study showed an annual amount of 10.44 m3/sec leaves the basin and never to return to the system. The study is useful in developing and calculating the annual water budget in the Big Lost River, and this process should be applicable to estimating water budgets in other basins.

Notes: : The Tualatin is the first watershed in Oregon to implement the Total Maximum Daily Load provisions of the Clean Water Act to deal with nonpoint source pollution. Local officials cite residential yard care practices as potential contributors to nonpoint source pollution in the basin. Qualitative and quantitative methods, including observation of yard maintenance styles, suggest behaviors potentially harmful to water quality and conservation. Yard maintenance is influenced by the importance of neighborhood appearance and concern for aesthetics. These concerns stimulate residents to water, fertilize, and apply weed control at more frequent intervals than yard care experts recommend. Better understanding of the effects that relations with neighbors and yard maintenance knowledge have on residential yard care practices can help improve water quality.

Notes: : In conventional flood damage reduction studies, flood damage is usually estimated with a damage function according to the depth of inundation. However, this method may not reflect the conditions of each family residing in the floodplain because it ignores not only the distribution of flood damage but also the effect of building characteristics and residents' preparedness. This paper uses data from a questionnaire based survey (N= 3,036) conducted 17 months after the Tokai Flood of 2000 that caused disastrous losses to household properties. It provides a conceptual “doughnut structure” model of flood damage to houses and house contents and a mathematical basis for models to explore the determinants of flood damage. Besides the inundation depth, house type significantly affects both the house structural and content damage probabilities, while house ownership and house structure affect house damage probability but not house content damage probability at a given depth. Inundation depth, residing period, and household income significantly affect both house and content damage values. In addition, house ownership has a significant impact on the house damage value, while house structure has an impact on content damage value.

Notes: : The rainfall-runoff response of the Tygarts Creek Catchment in eastern Kentucky is studied using TOPMODEL, a hydrologic model that simulates runoff at the catchment outlet based on the concepts of saturation excess overland flow and subsurface flow. Unlike the traditional application of this model to continuous rainfall-runoff data, the use of TOPMOEL in single event runoff modeling, specifically floods, is explored here. TOPMODEL utilizes a topographic index as an indicator of the likely spatial distribution of rainfall excess generation in the catchment. The topographic index values within the catchment are determined using the digital terrain analysis procedures in conjunction with digital elevation model (DEM) data. Select parameters in TOPMODEL are calibrated using an iterative procedure to obtain the best-fit runoff hydrograph. The calibrated parameters are the surface transmissivity, TO, the transmissivity decay parameter, m, and the initial moisture deficit in the root zone, Sr0. These parameters are calibrated using three storm events and verified using three additional storm events. Overall, the calibration results obtained in this study are in general agreement with the results documented from previous studies using TOPMODEL. However, the parameter values did not perform well during the verification phase of this study.

Notes: : Naturally formed plunge pools (scour holes) are a common morphologic feature in many urban stream systems where the transition between a pipe and a natural channel occurs. Plunge pools serve as significant stream energy dissipaters, increasing flow resistance and enhancing stream channel stability. Such features may also improve habitat diversity and serve as refugia for stream biota during low flow periods. The morphologic characteristics of several naturally formed plunge pools associated with road crossing culvert outlets in the metropolitan Charlotte, North Carolina, area are presented. Plunge pool dimensions surveyed include maximum depth, length, and width, and longitudinal and side slopes as well as bed material. Culvert outlet dimensions and hydraulic characteristics of the scouring jet for each study site are also reported. Design equations developed from flume studies generally failed to predict the naturally formed plunge pool dimensions. Pool volume was significantly correlated with drainage area, with pool depth being the least sensitive dimension to changes in the magnitude of the scouring flow. The excavation costs for designed plunge pools compare favorably to initial construction costs of traditional culvert outlet riprap aprons.

Notes: Increasing concern over the implications of climate change for biodiversity has led to the use of species–climate envelope models to project species extinction risk under climate-change scenarios. However, recent studies have demonstrated significant variability in model predictions and there remains a pressing need to validate models and to reduce uncertainties. Model validation is problematic as predictions are made for events that have not yet occurred. Resubstituition and data partitioning of present-day data sets are, therefore, commonly used to test the predictive performance of models. However, these approaches suffer from the problems of spatial and temporal autocorrelation in the calibration and validation sets. Using observed distribution shifts among 116 British breeding-bird species over the past ∼20 years, we are able to provide a first independent validation of four envelope modelling techniques under climate change. Results showed good to fair predictive performance on independent validation, although rules used to assess model performance are difficult to interpret in a decision-planning context. We also showed that measures of performance on nonindependent data provided optimistic estimates of models' predictive ability on independent data. Artificial neural networks and generalized additive models provided generally more accurate predictions of species range shifts than generalized linear models or classification tree analysis. Data for independent model validation and replication of this study are rare and we argue that perfect validation may not in fact be conceptually possible. We also note that usefulness of models is contingent on both the questions being asked and the techniques used. Implementations of species–climate envelope models for testing hypotheses and predicting future events may prove wrong, while being potentially useful if put into appropriate context.

Notes: The effects of atmospheric nitrogen (N) deposition on organic matter decomposition vary with the biochemical characteristics of plant litter. At the ecosystem-scale, net effects are difficult to predict because various soil organic matter (SOM) fractions may respond differentially. We investigated the relationship between SOM chemistry and microbial activity in three northern deciduous forest ecosystems that have been subjected to experimental N addition for 2 years. Extractable dissolved organic carbon (DOC), DOC aromaticity, C : N ratio, and functional group distribution, measured by Fourier transform infrared spectra (FTIR), were analyzed for litter and SOM. The largest biochemical changes were found in the sugar maple–basswood (SMBW) and black oak–white oak (BOWO) ecosystems. SMBW litter from the N addition treatment had less aromaticity, higher C : N ratios, and lower saturated carbon, lower carbonyl carbon, and higher carboxylates than controls; BOWO litter showed opposite trends, except for carbonyl and carboxylate contents. Litter from the sugar maple–red oak (SMRO) ecosystem had a lower C : N ratio, but no change in DOC aromaticity. For SOM, the C : N ratio increased with N addition in SMBW and SMRO ecosystems, but decreased in BOWO; N addition did not affect the aromaticity of DOC extracted from mineral soil. All ecosystems showed increases in extractable DOC from both litter and soil in response to N treatment. The biochemical changes are consistent with the divergent microbial responses observed in these systems. Extracellular oxidative enzyme activity has declined in the BOWO and SMRO ecosystems while activity in the SMBW ecosystem, particularly in the litter horizon, has increased. In all systems, enzyme activities associated with the hydrolysis and oxidation of polysaccharides have increased. At the ecosystem scale, the biochemical characteristics of the dominant litter appear to modulate the effects of N deposition on organic matter dynamics.

Notes: Daily global observations from the Advanced Very High-Resolution Radiometers on the series of meteorological satellites operated by the National Oceanic and Atmospheric Administration between 1982 and 1999 were used to generate a new weekly global burnt surface product at a resolution of 8 km. Comparison with independently available information on fire locations and timing suggest that while the time-series cannot yet be used to make accurate and quantitative estimates of global burnt area it does provide a reliable estimate of changes in location and season of burning on the global scale. This time-series was used to characterize fire activity in both northern and southern hemispheres on the basis of average seasonal cycle and interannual variability. Fire seasonality and fire distribution data sets have been combined to provide gridded maps at 0.5° resolution documenting the probability of fire occurring in any given season for any location. A multiannual variogram constructed from 17 years of observations shows good agreement between the spatial–temporal behavior in fire activity and the ‘El Niño’ Southern Oscillation events, showing highly likely connections between both phenomena.

Notes: Effective measures to counter the rising levels of carbon dioxide in the Earth's atmosphere require that we better understand the functioning of the global carbon cycle. Uncertainties about, in particular, the terrestrial carbon cycle's response to climate change remain high. We use a well-known stochastic inversion technique originally developed in nuclear physics, the Metropolis algorithm, to determine the full probability density functions (PDFs) of parameters of a terrestrial ecosystem model. By thus assimilating half-hourly eddy covariance measurements of CO2 and water fluxes, we can substantially reduce the uncertainty of approximately five model parameters, depending on prior uncertainties. Further analysis of the posterior PDF shows that almost all parameters are nearly Gaussian distributed, and reveals some distinct groups of parameters that are constrained together. We show that after assimilating only 7 days of measurements, uncertainties for net carbon uptake over 2 years for the forest site can be substantially reduced, with the median estimate in excellent agreement with measurements.

Notes: A fundamental challenge in understanding the global nitrogen cycle is the quantification of denitrification on large heterogeneous landscapes. Because floodplains are important sites for denitrification and nitrogen retention, we developed a generalized floodplain biogeochemical model to determine whether dams and flood-control levees affect floodplain denitrification by altering floodplain inundation. We combined a statistical model of floodplain topography with a model of hydrology and nitrogen biogeochemistry to simulate floods of different magnitude. The model predicted substantial decreases in NO3-N processing on floodplains whose overbank floods have been altered by levees and upstream dams. Our simulations suggest that dams may reduce nitrate processing more than setback levees. Levees increased areal floodplain denitrification rates, but this effect was offset by a reduction in the area inundated. Scenarios that involved a levee also resulted in more variability in N processing among replicate floodplains.Nitrate loss occurred rapidly and completely in our model floodplains. As a consequence, total flood volume and the initial mass of nitrate reaching a floodplain may provide reasonable estimates of total N processing on floodplains during floods. This finding suggests that quantifying the impact of dams and levees on floodplain denitrification may be possible using recent advances in remote sensing of floodplain topography and flood stage. Furthermore, when considering flooding over the long-term, the cumulative N processed by frequent smaller floods was estimated to be quite large relative to that processed by larger, less frequent floods. Our results suggest that floodplain denitrification may be greatly influenced by the pervasive anthropogenic flood-control measures that currently exist on most majors river floodplains throughout the world, and may have the potential to be impacted by future changes in flood probabilities that will likely occur as a result of climate shifts.

Notes: To estimate how tree photosynthesis modulates soil respiration, we simultaneously and continuously measured soil respiration and canopy photosynthesis over an oak-grass savanna during the summer, when the annual grass between trees was dead. Soil respiration measured under a tree crown reflected the sum of rhizosphere respiration and heterotrophic respiration; soil respiration measured in an open area represented heterotrophic respiration. Soil respiration was measured using solid-state CO2 sensors buried in soils and the flux-gradient method. Canopy photosynthesis was obtained from overstory and understory flux measurements using the eddy covariance method. We found that the diurnal pattern of soil respiration in the open was driven by soil temperature, while soil respiration under the tree was decoupled with soil temperature. Although soil moisture controlled the seasonal pattern of soil respiration, it did not influence the diurnal pattern of soil respiration. Soil respiration under the tree controlled by the root component was strongly correlated with tree photosynthesis, but with a time lag of 7–12 h. These results indicate that photosynthesis drives soil respiration in addition to soil temperature and moisture.

Notes: Atmospheric change may affect plant phenolic compounds, which play an important part in plant survival. Therefore, we studied the impacts of CO2 and O3 on the accumulation of 27 phenolic compounds in the short-shoot leaves of two European silver birch (Betula pendula Roth) clones (clones 4 and 80). Seven-year-old soil-grown trees were exposed in open-top chambers over three growing seasons to ambient and twice ambient CO2 and O3 concentrations singly and in combination in central Finland.Elevated CO2 increased the concentration of the phenolic acids (+25%), myricetin glycosides (+18%), catechin derivatives (+13%) and soluble condensed tannins (+19%) by increasing their accumulation in the leaves of the silver birch trees, but decreased the flavone aglycons (−7%) by growth dilution. Elevated O3 increased the concentration of 3,4′-dihydroxypropiophenone 3-β-d-glucoside (+22%), chlorogenic acid (+19%) and flavone aglycons (+4%) by inducing their accumulation possibly as a response to increased oxidative stress in the leaf cells. Nevertheless, this induction of antioxidant phenolic compounds did not seem to protect the birch leaves from detrimental O3 effects on leaf weight and area, but may have even exacerbated them. On the other hand, elevated CO2 did seem to protect the leaves from elevated O3 because all the O3-derived effects on the leaf phenolics and traits were prevented by elevated CO2. The effects of the chamber and elevated CO2 on some compounds changed over time in response to the changes in the leaf traits, which implies that the trees were acclimatizing to the altered environmental conditions. Although the two clones used possessed different composition and concentrations of phenolic compounds, which could be related to their different latitudinal origin and physiological characteristics, they responded similarly to the treatments. However, in some cases the variation in phenolic concentrations caused by genotype or chamber environment was much larger than the changes caused by either elevated CO2 or O3.

Notes: Sedimentary records from three Canadian High Arctic ponds on Ellesmere Island, spanning the last several thousand years, show major shifts in pond communities within the last ∼200 years. These paleolimnological data indicate that aquatic insect (Diptera: Chironomidae) populations rapidly expanded and greatly increased in community diversity beginning in the 19th century. These invertebrate changes coincided with striking shifts in algal (diatom) populations, indicating strong food-web effects because of climate warming and reduced ice-cover in ponds. Predicted future warming in the Arctic may produce ecological changes that exceed the large shifts that have already occurred since the 19th century.

Notes: We studied the interannual variation of surface water partial pressure of CO2 (pCO2) and the CO2 emissions from the 37 large Finnish lakes linking them to the water quality, catchment and climate attributes in 1996–2001. The lake water CO2 was measured three times a year in the study lakes in 1998 and 1999 and for the rest of the years the CO2 was modeled by measured alkalinity. The median annual CO2 emission to the atmosphere ranged between 1.49 and 2.29 mol m−2 a−1. The annual CO2 emission followed closely the annual precipitation pattern with the highest emission during the years when the precipitation was highest (r2=0.81–0.97, P〈0.05). There was a strong negative correlation (r2=0.50–0.82, P〈0.001) between O2 and CO2 saturation in the lake water during stratification suggesting effective decomposition of organic matter in the lakes. Furthermore, total phosphorus and the proportion of agricultural land in the catchment had significant positive correlations with CO2 saturation.

Notes: We investigated the effects of oxygen (O2) concentration on methane (CH4) production and oxidation in two humid tropical forests that differ in long-term, time-averaged soil O2 concentrations. We identified sources and sinks of CH4 through the analysis of soil gas concentrations, surface emissions, and carbon isotope measurements. Isotope mass balance models were used to calculate the fraction of CH4 oxidized in situ. Complementary laboratory experiments were conducted to determine the effects of O2 concentration on gross and net rates of methanogenesis. Field and laboratory experiments indicated that high levels of CH4 production occurred in soils that contained between 9±1.1% and 19±0.2% O2. For example, we observed CH4 concentrations in excess of 3% in soils with 9±1.1% O2. CH4 emissions from the lower O2 sites were high (22–101 nmol CH4 m−2 s−1), and were equal in magnitude to CH4 emissions from natural wetlands. During peak periods of CH4 efflux, carbon dioxide (CO2) emissions became enriched in 13C because of high methanogenic activity. Gross CH4 production was probably greater than flux measurements indicated, as isotope mass balance calculations suggested that 48–78% of the CH4 produced was oxidized prior to atmospheric egress. O2 availability influenced CH4 oxidation more strongly than methanogenesis. Gross CH4 production was relatively insensitive to O2 concentrations in laboratory experiments. In contrast, methanotrophic bacteria oxidized a greater fraction of total CH4 production with increasing O2 concentration, shifting the δ13C composition of CH4 to values that were more positive. Isotopic measurements suggested that CO2 was an important source of carbon for methanogenesis in humid forests. The δ13C value of methanogenesis was between −84‰ and −98‰, which is well within the range of CH4 produced from CO2 reduction, and considerably more depleted in 13C than CH4 formed from acetate.

Notes: We investigated the effects of three elevated atmospheric CO2 levels on a Populus deltoides plantation at Biosphere 2 Laboratory in Oracle Arizona. Stable isotopes of carbon have been used as tracers to separate the carbon present before the CO2 treatments started (old C), from that fixed after CO2 treatments began (new C). Tree growth at elevated [CO2] increased inputs to soil organic matter (SOM) by increasing the production of fine roots and accelerating the rate of root C turnover. However, soil carbon content decreased as [CO2] in the atmosphere increased and inputs of new C were not found in SOM. Consequently, the rates of soil respiration increased by 141% and 176% in the 800 and 1200 μL L−1 plantations, respectively, when compared with ambient [CO2] after 4 years of exposure. However, the increase in decomposition of old SOM (i.e. already present when CO2 treatments began) accounted for 72% and 69% of the increase in soil respiration seen under elevated [CO2]. This resulted in a net loss of soil C at a rate that was between 10 and 20 times faster at elevated [CO2] than at ambient conditions. The inability to retain new and old C in the soil may stem from the lack of stabilization of SOM, allowing for its rapid decomposition by soil heterotrophs.

Notes: Isoprene is the most abundant volatile hydrocarbon emitted by many tree species and has a major impact on tropospheric chemistry, leading to formation of pollutants and enhancing the lifetime of methane, a powerful greenhouse gas. Reliable estimates of global isoprene emission from different ecosystems demand a clear understanding of the processes of both production and consumption. Although the biochemistry of isoprene production has been studied extensively and environmental controls over its emission are relatively well known, the study of isoprene consumption in soil has been largely neglected.Here, we present results on the production and consumption of isoprene studied by measuring the following different components: (1) leaf and soil and (2) at the whole ecosystem level in two distinct enclosed ultraviolet light-depleted mesocosms at the Biosphere 2 facility: a cottonwood plantation with trees grown at ambient and elevated atmospheric CO2 concentrations and a tropical rainforest, under well watered and drought conditions. Consumption of isoprene by soil was observed in both systems. The isoprene sink capacity of litter-free soil of the agriforest stands showed no significant response to different CO2 treatments, while isoprene production was strongly depressed by elevated atmospheric CO2 concentrations. In both mesocosms, drought suppressed the sink capacity, but the full sink capacity of dry soil was recovered within a few hours upon rewetting. We conclude that soil uptake of atmospheric isoprene is likely to be modest but significant and needs to be taken into account for a comprehensive estimate of the global isoprene budget. More studies investigating the capacity of soils to uptake isoprene in natural conditions are clearly needed.

Notes: We took advantage of the distinctive system-level measurement capabilities of the Biosphere 2 Laboratory (B2L) to examine the effects of prolonged exposure to elevated [CO2] on carbon flux dynamics, above- and belowground biomass changes, and soil carbon and nutrient capital in plantation forest stands over 4 years. Annually coppiced stands of eastern cottonwoods (Populus deltoides) were grown under ambient (400 ppm) and two levels of elevated (800 and 1200 ppm) atmospheric [CO2] in carbon and N-replete soils of the Intensive Forestry Mesocosm in the B2L. The large semiclosed space of B2L uniquely enabled precise CO2 exchange measurements at the near ecosystem scale. Highly controllable climatic conditions within B2L also allowed for reproducible examination of CO2 exchange under different scales in space and time. Elevated [CO2] significantly stimulated whole-system maximum net CO2 influx by an average of 21% and 83% in years 3 and 4 of the experiment. Over the 4-year experiment, cumulative belowground, foliar, and total aboveground biomass increased in both elevated [CO2] treatments. After 2 years of growth at elevated [CO2], early season stand respiration was decoupled from CO2 influx aboveground, presumably because of accelerated fine root production from stored carbohydrates in the coppiced system prior to canopy development and to the increased soil carbohydrate status under elevated [CO2] treatments. Soil respiration was stimulated by elevated [CO2] whether measured at the system level in the undisturbed soil block, by soil collars in situ, or by substrate-induced respiration in vitro. Elevated [CO2] accelerated depletion of soil nutrients, phosphorus, calcium and potassium, after 3 years of growth, litter removal, and coppicing, especially in the upper soil profile, although total N showed no change. Enhancement of above- and belowground biomass production by elevated [CO2] accelerated carbon cycling through the coppiced system and did not sequester additional carbon in the soil.

Notes: Intensification of agriculture since the 1950s has enhanced the availability, competitive ability, crude protein content, digestibility and extended growing seasons of forage grasses. Spilled cereal grain also provides a rich food source in autumn and in winter. Long-distance migratory herbivorous geese have rapidly exploited these feeding opportunities and most species have shown expansions in range and population size in the last 50 years. Results of long-term studies are presented from two Arctic-breeding populations, the Svalbard pink-footed goose and the Greenland white-fronted goose (GWFG). GWFGs have shown major habitat shifts since the 1950s from winter use of plant storage organs in natural wetlands to feeding on intensively managed farmland. Declines in local density on, and abandonment of, unmodified traditional wintering habitat and increased reproductive success among those birds wintering on farmland suggest that density-dependent processes were not the cause of the shift in this winter-site-faithful population. Based on enhanced nutrient and energy intake rates, we argue that observed shifts in both species from traditionally used natural habitats to intensively managed farmland on spring staging and wintering areas have not necessarily been the result of habitat destruction. Increased food intake rates and potential demographic benefits resulting from shifts to highly profitable foraging opportunities on increasingly intensively managed farmland, more likely explain increases in goose numbers in these populations. The geographically exploratory behaviour of subdominant individuals enables the discovery and exploitation of new winter feeding opportunities and hence range expansion. Recent destruction of traditional habitats and declines in farming at northern latitudes present fresh challenges to the well being of both populations. More urgently, Canada geese colonizing breeding and moulting habitats of white-fronted geese in Greenland are further affecting their reproductive output.

Notes: Despite its importance in the terrestrial C cycle rhizosphere carbon flux (RCF) has rarely been measured for intact root–soil systems. We measured RCF for 8-year-old saplings of sugar maple (Acer saccharum) and yellow birch (Betula allegheniensis) collected from the Hubbard Brook Experimental Forest (HBEF), NH and transplanted into pots with native soil horizons intact. Five saplings of each species were pulse labeled with 13CO2 at ambient CO2 concentrations for 4–6 h, and the 13C label was chased through rhizosphere and bulk soil pools in organic and mineral horizons for 7 days. We hypothesized yellow birch roots would supply more labile C to the rhizosphere than sugar maple roots based on the presumed greater C requirements of ectomycorrhizal roots. We observed appearance of the label in rhizosphere soil of both species within the first 24 h, and a striking difference between species in the timing of 13C release to soil. In sugar maple, peak concentration of the label appeared 1 day after labeling and declined over time whereas in birch the label increased in concentration over the 7-day chase period. The sum of root and rhizomicrobial respiration in the pots was 19% and 26% of total soil respiration in sugar maple and yellow birch, respectively. Our estimate of the total amount of RCF released by roots was 6.9–7.1% of assimilated C in sugar maple and 11.2–13.0% of assimilated C in yellow birch. These fluxes extrapolate to 55–57 and 90–104 g C m−2 yr−1 from sugar maple and yellow birch roots, respectively. These results suggest RCF from both arbuscular mycorrhizal and ectomycorrhizal roots represents a substantial flux of C to soil in northern hardwood forests with important implications for soil microbial activity, nutrient availability and C storage.

Notes: We present an integrated modeling study designed to investigate changes in ecosystem level phenology over Europe associated with changes in climate pattern, by the North Atlantic Oscillation (NAO). We derived onset dates from processed NDVI data sets and used growing degree day (GDD) summations from the NCEP re-analysis to calibrate and validate a phenology model to predict the onset of the growing season over Europe. In a cross-validation hindcast, the model (PHENOM) is able to explain 63% of the variance in onset date for grid cells containing at least 50% mixed and boreal forest. Using a model developed from previous work we performed climate change scenarios, generating synthetic temperature and GDD distributions under a hypothetically increasing NAO. These new distributions were used to drive PHENOM and project changes in the timing of onset for forested cells over Europe. Results from the climate change scenarios indicate that, if the current trend in the NAO continues, there is the potential for a continued advance to the start of the growing season by as much as 13 days in some areas.

Notes: We examined the effects of atmospheric vapor pressure deficit (VPD) and soil moisture stress (SMS) on leaf- and stand-level CO2 exchange in model 3-year-old coppiced cottonwood (Populus deltoides Bartr.) plantations using the large-scale, controlled environments of the Biosphere 2 Laboratory. A short-term experiment was imposed on top of continuing, long-term CO2 treatments (43 and 120 Pa), at the end of the growing season. For the experiment, the plantations were exposed for 6–14 days to low and high VPD (0.6 and 2.5 kPa) at low and high volumetric soil moisture contents (25–39%). When system gross CO2 assimilation was corrected for leaf area, system net CO2 exchange (SNCE), integrated daily SNCE, and system respiration increased in response to elevated CO2. The increases were mainly as a result of the larger leaf area developed during growth at high CO2, before the short-term experiment; the observed decline in responses to SMS and high VPD treatments was partly because of leaf area reduction. Elevated CO2 ameliorated the gas exchange consequences of water stress at the stand level, in all treatments. The initial slope of light response curves of stand photosynthesis (efficiency of light use by the stand) increased in response to elevated CO2 under all treatments. Leaf-level net CO2 assimilation rate and apparent quantum efficiency were consistently higher, and stomatal conductance and transpiration were significantly lower, under high CO2 in all soil moisture and VPD combinations (except for conductance and transpiration in high soil moisture, low VPD). Comparisons of leaf- and stand-level gross CO2 exchange indicated that the limitation of assimilation because of canopy light environment (in well-irrigated stands; ratio of leaf : stand=3.2–3.5) switched to a predominantly individual leaf limitation (because of stomatal closure) in response to water stress (leaf : stand=0.8–1.3). These observations enabled a good prediction of whole stand assimilation from leaf-level data under water-stressed conditions; the predictive ability was less under well-watered conditions. The data also demonstrated the need for a better understanding of the relationship between leaf water potential, leaf abscission, and stand LAI.

Notes: Temperate forest ecosystems have recently been identified as an important net sink in the global carbon budget. The factors responsible for the strength of the sinks and their permanence, however, are less evident. In this paper, we quantify the present carbon sequestration in Thuringian managed coniferous forests. We quantify the effects of indirect human-induced environmental changes (increasing temperature, increasing atmospheric CO2 concentration and nitrogen fertilization), during the last century using BIOME-BGC, as well as the legacy effect of the current age-class distribution (forest inventories and BIOME-BGC). We focused on coniferous forests because these forests represent a large area of central European forests and detailed forest inventories were available.The model indicates that environmental changes induced an increase in biomass C accumulation for all age classes during the last 20 years (1982–2001). Young and old stands had the highest changes in the biomass C accumulation during this period. During the last century mature stands (older than 80 years) turned from being almost carbon neutral to carbon sinks. In high elevations nitrogen deposition explained most of the increase of net ecosystem production (NEP) of forests. CO2 fertilization was the main factor increasing NEP of forests in the middle and low elevations.According to the model, at present, total biomass C accumulation in coniferous forests of Thuringia was estimated at 1.51 t C ha−1 yr−1 with an averaged annual NEP of 1.42 t C ha−1 yr−1 and total net biome production of 1.03 t C ha−1 yr−1 (accounting for harvest). The annual averaged biomass carbon balance (BCB: biomass accumulation rate-harvest) was 1.12 t C ha−1 yr−1 (not including soil respiration), and was close to BCB from forest inventories (1.15 t C ha−1 yr−1). Indirect human impact resulted in 33% increase in modeled biomass carbon accumulation in coniferous forests in Thuringia during the last century. From the forest inventory data we estimated the legacy effect of the age-class distribution to account for 17% of the inventory-based sink. Isolating the environmental change effects showed that these effects can be large in a long-term, managed conifer forest.

Notes: This paper discusses the advantages and disadvantages of the different methods that separate net ecosystem exchange (NEE) into its major components, gross ecosystem carbon uptake (GEP) and ecosystem respiration (Reco). In particular, we analyse the effect of the extrapolation of night-time values of ecosystem respiration into the daytime; this is usually done with a temperature response function that is derived from long-term data sets. For this analysis, we used 16 one-year-long data sets of carbon dioxide exchange measurements from European and US-American eddy covariance networks. These sites span from the boreal to Mediterranean climates, and include deciduous and evergreen forest, scrubland and crop ecosystems.We show that the temperature sensitivity of Reco, derived from long-term (annual) data sets, does not reflect the short-term temperature sensitivity that is effective when extrapolating from night- to daytime. Specifically, in summer active ecosystems the long-term temperature sensitivity exceeds the short-term sensitivity. Thus, in those ecosystems, the application of a long-term temperature sensitivity to the extrapolation of respiration from night to day leads to a systematic overestimation of ecosystem respiration from half-hourly to annual time-scales, which can reach 〉25% for an annual budget and which consequently affects estimates of GEP. Conversely, in summer passive (Mediterranean) ecosystems, the long-term temperature sensitivity is lower than the short-term temperature sensitivity resulting in underestimation of annual sums of respiration.We introduce a new generic algorithm that derives a short-term temperature sensitivity of Reco from eddy covariance data that applies this to the extrapolation from night- to daytime, and that further performs a filling of data gaps that exploits both, the covariance between fluxes and meteorological drivers and the temporal structure of the fluxes. While this algorithm should give less biased estimates of GEP and Reco, we discuss the remaining biases and recommend that eddy covariance measurements are still backed by ancillary flux measurements that can reduce the uncertainties inherent in the eddy covariance data.

Notes: Observed responses of upland-oak vegetation of the eastern deciduous hardwood forest to changing CO2, temperature, precipitation and tropospheric ozone (O3) were derived from field studies and interpreted with a stand-level model for an 11-year range of environmental variation upon which scenarios of future environmental change were imposed. Scenarios for the year 2100 included elevated [CO2] and [O3] (+385 ppm and +20 ppb, respectively), warming (+4°C), and increased winter precipitation (+20% November–March). Simulations were run with and without adjustments for experimentally observed physiological and biomass adjustments.Initial simplistic model runs for single-factor changes in CO2 and temperature predicted substantial increases (+191% or 508 g C m−2 yr−1) or decreases (−206% or −549 g C m−2 yr−1), respectively, in mean annual net ecosystem carbon exchange (NEEa≈266±23 g C m−2 yr−1 from 1993 to 2003). Conversely, single-factor changes in precipitation or O3 had comparatively small effects on NEEa (0% and −35%, respectively). The combined influence of all four environmental changes yielded a 29% reduction in mean annual NEEa. These results suggested that future CO2-induced enhancements of gross photosynthesis would be largely offset by temperature-induced increases in respiration, exacerbation of water deficits, and O3-induced reductions in photosynthesis. However, when experimentally observed physiological adjustments were included in the simulations (e.g. acclimation of leaf respiration to warming), the combined influence of the year 2100 scenario resulted in a 20% increase in NEEa not a decrease. Consistent with the annual model's predictions, simulations with a forest succession model run for gradually changing conditions from 2000 to 2100 indicated an 11% increase in stand wood biomass in the future compared with current conditions.These model-based analyses identify critical areas of uncertainty for multivariate predictions of future ecosystem response, and underscore the importance of long term field experiments for the evaluation of acclimation and growth under complex environmental scenarios.

Notes: Land-use changes have contributed to increased atmospheric CO2 concentrations. Conversion from natural peatlands to agricultural land has led to widespread subsidence of the peat surface caused by soil compaction and mineralization. To study the net ecosystem exchange of carbon (C) and the contribution of respiration to peat subsidence, eddy covariance measurements were made over pasture on a well-developed, drained peat soil from 22 May 2002 to 21 May 2003. The depth to the water table fluctuated between 0.02 m in winter 2002 to 0.75 m during late summer and early autumn 2003. Peat soil moisture content varied between 0.6 and 0.7 m3 m−3 until the water table dropped below 0.5 m, when moisture content reached 0.38 m3 m−3. Neither depth to water table nor soil moisture was found to have an effect on the rate of night-time respiration (ranging from 0.4–8.0 μmol CO2 m−2 s−1 in winter and summer, respectively). Most of the variance in night-time respiration was explained by changes in the 0.1 m soil temperature (r2=0.93). The highest values for daytime net ecosystem exchange were measured in September 2002, with a maximum of −17.2 μmol CO2 m−2 s−1. Grazing events and soil moisture deficiencies during a short period in summer reduced net CO2 exchange. To establish an annual C balance for this ecosystem, non-linear regression was used to model missing data. Annually integrated (CO2) C exchange for this peat–pasture ecosystem was 45±500 kg C ha−1 yr−1. After including other C exchanges (methane emissions from cows and production of milk), the net annual C loss was 1061±500 kg C ha−1 yr−1.

Notes: We used snow fences and small (1 m2) open-topped fiberglass chambers (OTCs) to study the effects of changes in winter snow cover and summer air temperatures on arctic tundra. In 1994, two 60 m long, 2.8 m high snow fences, one in moist and the other in dry tundra, were erected at Toolik Lake, Alaska. OTCs paired with unwarmed plots, were placed along each experimental snow gradient and in control areas adjacent to the snowdrifts. After 8 years, the vegetation of the two sites, including that in control plots, had changed significantly. At both sites, the cover of shrubs, live vegetation, and litter, together with canopy height, had all increased, while lichen cover and diversity had decreased. At the moist site, bryophytes decreased in cover, while an increase in graminoids was almost entirely because of the response of the sedge Eriophorum vaginatum. These community changes were consistent with results found in studies of responses to warming and increased nutrient availability in the Arctic. However, during the time period of the experiment, summer temperature did not increase, but summer precipitation increased by 28%. The snow addition treatment affected species abundance, canopy height, and diversity, whereas the summer warming treatment had few measurable effects on vegetation. The interannual temperature fluctuation was considerably larger than the temperature increases within OTCs (〈2°C), however. Snow addition also had a greater effect on microclimate by insulating vegetation from winter wind and temperature extremes, modifying winter soil temperatures, and increasing spring run-off. Most increases in shrub cover and canopy height occurred in the medium snow-depth zone (0.5–2 m) of the moist site, and the medium to deep snow-depth zone (2–3 m) of the dry site. At the moist tundra site, deciduous shrubs, particularly Betula nana, increased in cover, while evergreen shrubs decreased. These differential responses were likely because of the larger production to biomass ratio in deciduous shrubs, combined with their more flexible growth response under changing environmental conditions. At the dry site, where deciduous shrubs were a minor part of the vegetation, evergreen shrubs increased in both cover and canopy height. These changes in abundance of functional groups are expected to affect most ecological processes, particularly the rate of litter decomposition, nutrient cycling, and both soil carbon and nitrogen pools. Also, changes in canopy structure, associated with increases in shrub abundance, are expected to alter the summer energy balance by increasing net radiation and evapotranspiration, thus altering soil moisture regimes.

Notes: The phenological state of vegetation significantly affects exchanges of heat, mass, and momentum between the Earth's surface and the atmosphere. Although current patterns can be estimated from satellites, we lack the ability to predict future trends in response to climate change. We searched the literature for a common set of variables that might be combined into an index to quantify the greenness of vegetation throughout the year. We selected as variables: daylength (photoperiod), evaporative demand (vapor pressure deficit), and suboptimal (minimum) temperatures. For each variable we set threshold limits, within which the relative phenological performance of the vegetation was assumed to vary from inactive (0) to unconstrained (1). A combined Growing Season Index (GSI) was derived as the product of the three indices. Ten-day mean GSI values for nine widely dispersed ecosystems showed good agreement (r〉0.8) with the satellite-derived Normalized Difference Vegetation Index (NDVI). We also tested the model at a temperate deciduous forest by comparing model estimates with average field observations of leaf flush and leaf coloration. The mean absolute error of predictions at this site was 3 days for average leaf flush dates and 2 days for leaf coloration dates. Finally, we used this model to produce a global map that distinguishes major differences in regional phenological controls. The model appears sufficiently robust to reconstruct historical variation as well as to forecast future phenological responses to changing climatic conditions.

Notes: Many species are predicted to shift their ranges to higher latitudes and altitudes in response to climate warming. This study presents evidence for 37 species of nonmigratory British dragonflies and damselflies shifting northwards at their range margins over the past 40 years, seemingly as a result of climate change. This response by an exemplar group of insects associated with fresh water, parallels polewards range changes observed in terrestrial invertebrates and other taxa.

Notes: Operational monitoring of global terrestrial gross primary production (GPP) and net primary production (NPP) is now underway using imagery from the satellite-borne Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. Evaluation of MODIS GPP and NPP products will require site-level studies across a range of biomes, with close attention to numerous scaling issues that must be addressed to link ground measurements to the satellite-based carbon flux estimates. Here, we report results of a study aimed at evaluating MODIS NPP/GPP products at six sites varying widely in climate, land use, and vegetation physiognomy. Comparisons were made for twenty-five 1 km2 cells at each site, with 8-day averages for GPP and an annual value for NPP. The validation data layers were made with a combination of ground measurements, relatively high resolution satellite data (Landsat Enhanced Thematic Mapper Plus at ∼30 m resolution), and process-based modeling. There was strong seasonality in the MODIS GPP at all sites, and mean NPP ranged from 80 g C m−2 yr−1 at an arctic tundra site to 550 g C m−2 yr−1 at a temperate deciduous forest site. There was not a consistent over- or underprediction of NPP across sites relative to the validation estimates. The closest agreements in NPP and GPP were at the temperate deciduous forest, arctic tundra, and boreal forest sites. There was moderate underestimation in the MODIS products at the agricultural field site, and strong overestimation at the desert grassland and at the dry coniferous forest sites. Analyses of specific inputs to the MODIS NPP/GPP algorithm – notably the fraction of photosynthetically active radiation absorbed by the vegetation canopy, the maximum light use efficiency (LUE), and the climate data – revealed the causes of the over- and underestimates. Suggestions for algorithm improvement include selectively altering values for maximum LUE (based on observations at eddy covariance flux towers) and parameters regulating autotrophic respiration.

Notes: A critical global climate change issue is how increasing concentrations of atmospheric CO2 and ground-level O3 will affect agricultural productivity. This includes effects on decomposition of residues left in the field and availability of mineral nutrients to subsequent crops. To address questions about decomposition processes, a 2-year experiment was conducted to determine the chemistry and decomposition rate of aboveground residues of soybean (Glycine max (L.) Merr.) grown under reciprocal combinations of low and high concentrations of CO2 and O3 in open-top field chambers. The CO2 treatments were ambient (370 μmol mol−1) and elevated (714 μmol mol−1) levels (daytime 12 h averages). Ozone treatments were charcoal-filtered air (21 nmol mol−1) and nonfiltered air plus 1.5 times ambient O3 (74 nmol mol−1) 12 h day−1. Elevated CO2 increased aboveground postharvest residue production by 28–56% while elevated O3 suppressed it by 15–46%. In combination, inhibitory effects of added O3 on biomass production were largely negated by elevated CO2. Plant residue chemistry was generally unaffected by elevated CO2, except for an increase in leaf residue lignin concentration. Leaf residues from the elevated O3 treatments had lower concentrations of nonstructural carbohydrates, but higher N, fiber, and lignin levels. Chemical composition of petiole, stem, and pod husk residues was only marginally affected by the elevated gas treatments. Treatment effects on plant biomass production, however, influenced the content of chemical constituents on an areal basis. Elevated CO2 increased the mass per square meter of nonstructural carbohydrates, phenolics, N, cellulose, and lignin by 24–46%. Elevated O3 decreased the mass per square meter of these constituents by 30–48%, while elevated CO2 largely ameliorated the added O3 effect. Carbon mineralization rates of component residues from the elevated gas treatments were not significantly different from the control. However, N immobilization increased in soils containing petiole and stem residues from the elevated CO2, O3, and combined gas treatments. Mass loss of decomposing leaf residue from the added O3 and combined gas treatments was 48% less than the control treatment after 20 weeks, while differences in decomposition of petiole, stem, and husk residues among treatments were minor. Decreased decomposition of leaf residues was correlated with lower starch and higher lignin levels. However, leaf residues only comprised about 20% of the total residue biomass assayed so treatment effects on mass loss of total aboveground residues were relatively small. The primary influence of elevated atmospheric CO2 and O3 concentrations on decomposition processes is apt to arise from effects on residue mass input, which is increased by elevated CO2 and suppressed by O3.

Notes: A unique 113-year record of numbers of nine migrating butterflies and 20 migrating moths is examined in relation to temperatures on the migration route, to temperatures in England, and to the North Atlantic oscillation (NAO). This study clearly reveals the strong association between numbers of migrant Lepidoptera and temperatures in France; with higher temperatures associated with increased migrant numbers. The NAO also appears influential with high index years associated with increased numbers. The strong temperature link suggests that Britain and other northern temperate countries can expect to receive larger numbers of migrant Lepidoptera if climate warms as predicted in the 21st century.

Notes: The impact of ambient ultraviolet (UV)-B radiation on the endemic bryophyte, Grimmia antarctici, was studied over 14 months in East Antarctica. Over recent decades, Antarctic plants have been exposed to the largest relative increase in UV-B exposure as a result of ozone depletion. We investigated the effect of reduced UV and visible radiation on the pigment concentrations, surface reflectance and physiological and morphological parameters of this moss. Plexiglass screens were used to provide both reduced UV levels (77%) and a 50% decrease in total radiation. The screen combinations were used to separate UV photoprotective from visible photoprotective strategies, because these bryophytes are growing in relatively high light environments compared with many mosses. G. antarctici was affected negatively by ambient levels of UV radiation. Chlorophyll content was significantly lower in plants grown under near-ambient UV, while the relative proportions of photoprotective carotenoids, especially β-carotene and zeaxanthin, increased. However, no evidence for the accumulation of UV-B-absorbing pigments in response to UV radiation was observed. Although photosynthetic rates were not affected, there was evidence of UV effects on morphology. Plants that were shaded showed fewer treatment responses and these were similar to the natural variation observed between moss growing on exposed microtopographical ridges and in more sheltered valleys within the turf. Given that other Antarctic bryophytes possess UV-B-absorbing pigments which should offer better protection under ambient UV-B radiation, these findings suggest that G. antarctici may be disadvantaged in some settings under a climate with continuing high levels of springtime UV-B radiation.