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  • 1
    Electronic Resource
    Electronic Resource
    Species diversity enhances ecosystem functioning through interspecific facilitation (2002)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 415 (2002), S. 426-429 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Facilitation between species is thought to be a key mechanism by which biodiversity affects the rates of resource use that govern the efficiency and productivity of ecosystems; however, there is no direct empirical evidence to support this hypothesis. Here we show that increasing the species ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/415426a
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  • 2
    Electronic Resource
    Electronic Resource
    Soil Heterogeneity Effects on Tallgrass Prairie Community Heterogeneity: An Application of Ecological Theory to Restoration Ecology (2005)
    Oxford, UK; Malden, USA : Blackwell Science Inc
    Restoration ecology 13 (2005), S. 0 
    Details
    ISSN: 1526-100X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Spatial heterogeneity of resources can influence plant community composition and diversity in natural communities. We manipulated soil depth (two levels) and nutrient availability (three levels) to create four heterogeneity treatments (no heterogeneity, depth heterogeneity, nutrient heterogeneity, and depth + nutrient heterogeneity) replicated in an agricultural field seeded to native prairie species. Our objective was to determine whether resource heterogeneity influences species diversity and the trajectory of community development during grassland restoration. The treatments significantly increased heterogeneity of available inorganic nitrogen (N), soil water content, and light penetration. Plant diversity was indirectly related to resource heterogeneity through positive relationships with variability in productivity and cover established by the belowground manipulations. Diversity was inversely correlated with the average cover of the dominant grass, Switchgrass (Panicum virgatum), which increased over time in all heterogeneity treatments and resulted in community convergence among the heterogeneity treatments over time. The success of this cultivar across the wide range of resource availability was attributed to net photosynthesis rates equivalent to or higher than those of the native prairie plants in the presence of lower foliar N content. Our results suggest that resource heterogeneity alone may not increase diversity in restorations where a dominant species can successfully establish across the range of resource availability. This is consistent with theory regarding the role of ecological filters on community assembly in that the establishment of one species best adapted for the physical and biological conditions can play an inordinately important role in determining community structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1526-100X.2005.00051.x
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  • 3
    Electronic Resource
    Electronic Resource
    Altering Rainfall Timing and Quantity in a Mesic Grassland Ecosystem: Design and Performance of Rainfall Manipulation Shelters (2000)
    Springer
    Ecosystems 3 (2000), S. 308-319 
    Details
    ISSN: 1435-0629
    Keywords: Key words: climate change; precipitation patterns; rainout shelters; grasslands; soil moisture; net primary production; floristic diversity; life histories; Konza Prairie; long-term research.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Global climate change is predicted to alter growing season rainfall patterns, potentially reducing total amounts of growing season precipitation and redistributing rainfall into fewer but larger individual events. Such changes may affect numerous soil, plant, and ecosystem properties in grasslands and ultimately impact their productivity and biological diversity. Rainout shelters are useful tools for experimental manipulations of rainfall patterns, and permanent fixed-location shelters were established in 1997 to conduct the Rainfall Manipulation Plot study in a mesic tallgrass prairie ecosystem in northeastern Kansas. Twelve 9 x 14–m fixed-location rainfall manipulation shelters were constructed to impose factorial combinations of 30% reduced rainfall quantity and 50% greater interrainfall dry periods on 6 x 6–m plots, to examine how altered rainfall regimes may affect plant species composition, nutrient cycling, and above- and belowground plant growth dynamics. The shelters provided complete control of growing season rainfall patterns, whereas effects on photosynthetic photon flux density, nighttime net radiation, and soil temperature generally were comparable to other similar shelter designs. Soil and plant responses to the first growing season of rainfall manipulations (1998) suggested that the interval between rainfall events may be a primary driver in grassland ecosystem responses to altered rainfall patterns. Aboveground net primary productivity, soil CO2 flux, and flowering duration were reduced by the increased interrainfall intervals and were mostly unaffected by reduced rainfall quantity. The timing of rainfall events and resulting temporal patterns of soil moisture relative to critical times for microbial activity, biomass accumulation, plant life histories, and other ecological properties may regulate longer-term responses to altered rainfall patterns.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100210000028
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  • 4
    Electronic Resource
    Electronic Resource
    Tree dispersion in oak-dominated forests along an environmental gradient (1991)
    Springer
    Oecologia 86 (1991), S. 471-477 
    Details
    ISSN: 1432-1939
    Keywords: Aggregation ; Competition ; Forest ; Oklahoma ; Pattern analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Spatial pattern was analyzed in seventeen stands of oak-dominated forest to address the hypothesis that species tended to be aggregated under favorable conditions and widely spaced in xeric, nutrient poor conditions. Trees were sampled at 80–100 points in each stand with the distance-to-nearest neighbor method. Soil samples were collected in each stand for analysis of total nitrogen, total phosphorus, total potassium, soil pH, soil texture, and soil organic matter. Growing season precipitation was also recorded from climate stations near each stand. Quercus stellata (Wang.) dominated 10 stands, Q. marilandica (Muenchh.) dominated three stands and these species were codominant in four stands. Principal components analysis identified a soil texture/fertility gradient across the study area. Quercus stellata and all species combined were aggregated in most stands, whereas Q. marilandica was mostly randomly distributed within a stand. Small trees of all species combined tended to be aggregated and large trees were randomly dispersed in all but two stands, suggesting competition. Mean distance between large-large pairs was always greater than mean distance between small-small pairs in all stands, but this difference was only significant in one stand. Correlations between nearest neighbor distance and combined size of nearest neighbors were significant and positive in 12 of 17 stands. In all cases, however, slopes were shallow suggesting that competition is weak in these communities and has a limited effect on spacing of neighboring trees. Contrary to our hypothesis, trees were more aggregated on coarse-textured soils with low organic matter content. For all species combined, degree of aggregation was unrelated to growing season precipitation. Aggregation appears to be common in these forests because environmental stress in many stands reduces growth rates. Trees have not yet reached a size at which competition or other interactions can greatly increase interplant distances and reduce the degree of aggregation. A simple graphical model is developed to describe the relationship between patterns, stress and competition in plant communities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318312
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  • 5
    Electronic Resource
    Electronic Resource
    Geographic variation in habitat structure for the wood warblers in Maine and Minnesota (1983)
    Springer
    Oecologia 59 (1983), S. 246-252 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The habitats occupied by species of wood warblers (Emberizidae) were compared at two study areas, Itasca State Park, Minnesota and Mount Blue State Park, Maine. Univariate comparisons of each variable of habitat structure show geographic differences for each species of warbler. Habitats available were also different because small trees were always more dense in Maine than in Minnesota. The Black-throated Green Warbler had the most dissimilar habitat with 9 of 11 variables different at the two sites. Cluster analysis identified four generalized habitat groups containing (1) species occupying territories with high percent shrub cover, (2) forest species from Maine, (3) forest species from Minnesota and (4) open country species. Reciprocal averaging ordination was used to identify habitat gradients at each site. The first axis of the Maine and Minnesota ordinations was a gradient from open country with dense ground cover to forest vegetation. The second axes differed, however. In Minnesota, the gradient separated medium deciduous trees from large conifers, whereas in Maine, vegetation graded from medium and large deciduous trees to coniferous habitats. Spearman rank correlation indicated that the warblers were similarly arranged along both habitat axes at each site despite differences in axis loadings of habitat variables. A combined reciprocal averaging ordination separated forest and shrub-forest edge species in Maine from the same two species groups in Minnesota along a smaller to larger tree axis. The results clearly demonstrate that habitat structure is not consistent throughout the range of many widely distributed species. It is suggested that the similar arrangement of species along the habitat axes probably results from an individualistic distribution of opportunistic bird species. Variation is probably induced at a site level by intraspecific competition for territories, small-scale vegetation dynamics, and resource fluctuation that occurs both within and between seasons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378844
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  • 6
    Electronic Resource
    Electronic Resource
    Disturbances in tallgrass prairie: local and regional effects on community heterogeneity (1992)
    Springer
    Landscape ecology 7 (1992), S. 243-251 
    Details
    ISSN: 1572-9761
    Keywords: Hierarchy ; scale ; disturbance ; heterogeneity ; tallgrass prairie ; plant communities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Community heterogeneity in tallgrass prairie was analyzed at regional and local levels to assess the effects of disturbances on community structure at different spatial scales. The sites were part of NASA's First ISLSCP Field Experiment (FIFE) in Kansas, and were located on grassland treatments that were undisturbed, and burned-only on Konze Prairie Research Natural Area, and grazed-only and grazed + burned on adjacent ranch land. Sites in grazed-only or grazed + burned treatments were less similar to each other, on a regional scale (15 × 15 km), than were burned-only or undisturbed sites. Grazing reduced the cover of dominant species, making space available for the establishment of immigrants from the region. Each site was different because of establishment by different species from the large regional species pool. At the local scale (0.1 ha), the most homogeneous treatments were those that were most heterogeneous at the regional scale. Undisturbed treatments at the local scale were the most heterogeneous compared to sites under other treatments. Therefore, regional responses to disturbances were more variable than local responses, and were not predictable from within-site analyses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00131255
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  • 7
    Electronic Resource
    Electronic Resource
    Succession and fluctuation in Artemisia dominated grassland (1988)
    Springer
    Plant ecology 73 (1988), S. 89-99 
    Details
    ISSN: 1573-5052
    Keywords: Artemisia filifolia ; Diversity ; Exclosure ; Fluctuation ; Grazing ; Oklahoma ; Sand sagebrush grassland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Vegetation dynamics were studied from 1940 to 1978 in two grazed pastures and associated exclosures in sand sagebrush (Artemisia filifolia) dominated grassland, western Oklahoma, USA. In both pastures and one exclosure, pattern of vegetation change reflected fluctuation rather than succession. In the other exclosure, the grassland exhibited a directional change from annual grasses and forbs to dominance by perennial grasses. Rate of change was consistent during the 39 year period. Cover of grasses increased more in grazed than ungrazed areas. Grass cover was negatively correlated with high air temperatures early in the growing season. Forb cover remained relatively constant over time and shrub cover peaked during the 1960s. Abundance of annuals and cool season species was positively correlated with rainfall early in the growing season. Species diversity and richness were lowest in the ungrazed areas, as a result of increased dominance by perennial grasses such as Schizachyrium scoparium. In pastures and exclosures, richness was positively correlated with growing season precipitation. Cover of the common species differed among sample areas within years and fluctuated between years. Few general patterns emerged from correlations of environmental variables with cover of individual species. In general, vegetation dynamics in these sand sagebrush grasslands reflect a tradeoff in that total cover changes little over time because the loss of some species is compensated for by increased growth of others. Such trade-offs reflect the individualistic response of the component species within each pasture or exclosure. Although changes in growth form composition were related to climatic fluctuation, broad-scale climatic variables could not successfully predict small-scale patterns of change by individual species over time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00031856
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of disturbance on diversity in mixed-grass prairie (1986)
    Springer
    Plant ecology 64 (1986), S. 87-94 
    Details
    ISSN: 1573-5052
    Keywords: Buffalo wallow ; Disturbance ; Diversity ; Fire ; Grassland ; Grazing ; Oklahoma ; Prairie dog town
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seven grassland treatments representing different disturbance regimes were sampled within a large area of mixed-grass prairie in southwestern Oklahoma, USA. Species diversity was low on the undisturbed and most severely disturbed grasslands. The results also indicate, however, that grassland diversity was not a simple function of disturbance rate, size or intensity. Instead, species diversity was maximized under a combination of natural disturbances. To some extent, the increase in species diversity was the result of increased habitat diversity associated with a type of disturbance. That is, disturbances such as grazing and wallowing have a cumulative effect one grassland diversity. Overall, the structure one grassland communities can not be accurately determined without considering the structure of the natural disturbance regime.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00044784
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  • 9
    Electronic Resource
    Electronic Resource
    Experimental analysis of patch dynamics and community heterogeneity in tallgrass prairie (1989)
    Springer
    Plant ecology 85 (1989), S. 57-66 
    Details
    ISSN: 1573-5052
    Keywords: Community heterogeneity ; Fire, Microsuccession ; Oklahoma ; Soil disturbance ; Species richness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Effects of fire and small-scale soil disturbances on species richness, community heterogeneity, and microsuccession were investigated in a central Oklahoma tallgrass prairie. In the fall of 1985, 0.2 m2 soil disturbances were created on burned and unburned tallgrass prairie. Vegetation on and off disturbances was sampled at monthly intervals over two growing seasons. During the first growing season, the cover of forbs and annuals, and species richness were significantly greater on versus off disturbances, but these differences did not persist through the second year. The variation in species composition among disturbed plots (heterogeneity) was significantly greater compared to undisturbed areas throughout the study. Fire had no consistent effect on richness and heterogeneity of vegetation on soil disturbances but fire reduced heterogeneity on undisturbed vegetation. Rate of succession, based on an increase in cumulative cover of perennial grasses over time, did not differ among treatments during the first growing season. During the second year, rate of succession was significantly greater on burned soil disturbances compared to unburned soil disturbances. These results suggest that while small-scale soil disturbances have primarily short-lived effects on grassland community structure, disturbances do help to maintain spatial and temporal variation in tallgrass prairie communities. Unlike in undisturbed vegetation, however, species richness and heterogeneity on soil disturbances were little effected by fire, but the rate of colonization onto disturbances appeared to be enhanced by fire.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042255
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  • 10
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    Long-term ecological research in a human-dominated world (2012)
    American Institute of Biological Sciences
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © American Institute of Biological Sciences, 2012. This article is posted here by permission of American Institute of Biological Sciences for personal use, not for redistribution. The definitive version was published in BioScience 62 (2012): 342-253, doi:10.1525/bio.2012.62.4.6.
    Description: The US Long Term Ecological Research (LTER) Network enters its fourth decade with a distinguished record of achievement in ecological science. The value of long-term observations and experiments has never been more important for testing ecological theory and for addressing today's most difficult environmental challenges. The network's potential for tackling emergent continent-scale questions such as cryosphere loss and landscape change is becoming increasingly apparent on the basis of a capacity to combine long-term observations and experimental results with new observatory-based measurements, to study socioecological systems, to advance the use of environmental cyberinfrastructure, to promote environmental science literacy, and to engage with decisionmakers in framing major directions for research. The long-term context of network science, from understanding the past to forecasting the future, provides a valuable perspective for helping to solve many of the crucial environmental problems facing society today.
    Description: 2012-10-01
    Keywords: Coupled natural—human systems ; Cyberinfrastructure ; Environmental observatories ; Environmental education ; Socioecological systems
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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