ALBERT

Description: The global terrestrial carbon sink has increased since the start of this century at a time of growing carbon emissions from fossil fuel burning. Here we test the hypothesis that increases in atmospheric aerosols from fossil fuel burning enhanced the diffuse light fraction and the efficiency of plant carbon uptake. Using a combination of models, we estimate that at global scale changes in light regimes from fossil fuel aerosol emissions had only a small negative effect on the increase in terrestrial net primary production over the period 1998-2010. Hereby, the substantial increases in fossil fuel aerosol emissions and plant carbon uptake over East Asia were effectively cancelled by opposing trends across Europe and North America. This suggests that if the recent increase in the land carbon sink would be causally linked to fossil fuel emissions it is unlikely via the effect of aerosols but due to other factors such as nitrogen deposition or nitrogen-carbon interactions.

Description: The Amazon Basin has experienced more variable climate over the last decade, with a severe and widespread drought in 2005 causing large basin-wide losses of biomass. A drought of similar climatological magnitude occurred again in 2010; however, there has been no basin-wide ground-based evaluation of effects on vegetation. We examine to what extent the 2010 drought affected forest dynamics using ground-based observations of mortality and growth utilizing data from an extensive forest plot network. We find that during the 2010 drought interval, forests did not gain biomass (net change: −0.43 Mg ha -1 , CI: −1.11, 0.19, n = 97), regardless of whether forests experienced precipitation deficit anomalies. This loss contrasted with a long-term biomass sink during the baseline pre-2010 drought period (1998 − pre-2010) of 1.33 Mg ha -1 yr -1 (CI: 0.90, 1.74, p  〈 0.01). The resulting net impact of the 2010 drought (i.e., reversal of the baseline net sink) was −1.95 Mg ha -1 yr -1 (CI:−2.77, −1.18; p  〈 0.001). This net biomass impact was driven by an increase in biomass mortality (1.45 Mg ha -1 yr -1 CI: 0.66, 2.25, p  〈 0.001), and a decline in biomass productivity (−0.50 Mg ha -1 yr -1 , CI:−0.78, −0.31; p  〈 0.001). Surprisingly, the magnitude of the losses through tree mortality was unrelated to estimated local precipitation anomalies, and was independent of estimated local pre-2010 drought history. Thus, there was no evidence that pre-2010 droughts compounded the effects of the 2010 drought. We detected a systematic basin-wide impact of drought on tree growth rates across Amazonia, with this suppression of productivity driven by moisture deficits in 2010, an impact which was not apparent during the 2005 event [ Phillips et al. , 2009]. Based on these ground data, both live biomass in trees and corresponding estimates of live biomass in roots, we estimate that intact forests in Amazonia were carbon neutral in 2010 (−0.07 PgC yr -1 CI:−0.42, 0.23), consistent with results from an independent analysis of airborne estimates of land-atmospheric fluxes during 2010 [ Gatti et al. , 2014]. Relative to the long-term mean, the 2010 drought resulted in a reduction in biomass carbon uptake of 1.1 PgC, compared to 1.6 PgC for the 2005 event [ Phillips et al . 2009].

Description: Volume 70, Issue 1, December 2018, Page 1-14〈br/〉. 〈br/〉

Description: Amazon forests are a key but poorly understood component of the global carbon cycle. If, as anticipated, they dry this century, they might accelerate climate change through carbon losses and changed surface energy balances. We used records from multiple long-term monitoring plots across Amazonia to assess forest responses to the intense 2005 drought, a possible analog of future events. Affected forest lost biomass, reversing a large long-term carbon sink, with the greatest impacts observed where the dry season was unusually intense. Relative to pre-2005 conditions, forest subjected to a 100-millimeter increase in water deficit lost 5.3 megagrams of aboveground biomass of carbon per hectare. The drought had a total biomass carbon impact of 1.2 to 1.6 petagrams (1.2 x 10(15) to 1.6 x 10(15) grams). Amazon forests therefore appear vulnerable to increasing moisture stress, with the potential for large carbon losses to exert feedback on climate change.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Phillips, Oliver L -- Aragao, Luiz E O C -- Lewis, Simon L -- Fisher, Joshua B -- Lloyd, Jon -- Lopez-Gonzalez, Gabriela -- Malhi, Yadvinder -- Monteagudo, Abel -- Peacock, Julie -- Quesada, Carlos A -- van der Heijden, Geertje -- Almeida, Samuel -- Amaral, Ieda -- Arroyo, Luzmila -- Aymard, Gerardo -- Baker, Tim R -- Banki, Olaf -- Blanc, Lilian -- Bonal, Damien -- Brando, Paulo -- Chave, Jerome -- de Oliveira, Atila Cristina Alves -- Cardozo, Nallaret Davila -- Czimczik, Claudia I -- Feldpausch, Ted R -- Freitas, Maria Aparecida -- Gloor, Emanuel -- Higuchi, Niro -- Jimenez, Eliana -- Lloyd, Gareth -- Meir, Patrick -- Mendoza, Casimiro -- Morel, Alexandra -- Neill, David A -- Nepstad, Daniel -- Patino, Sandra -- Penuela, Maria Cristina -- Prieto, Adriana -- Ramirez, Fredy -- Schwarz, Michael -- Silva, Javier -- Silveira, Marcos -- Thomas, Anne Sota -- Steege, Hans Ter -- Stropp, Juliana -- Vasquez, Rodolfo -- Zelazowski, Przemyslaw -- Alvarez Davila, Esteban -- Andelman, Sandy -- Andrade, Ana -- Chao, Kuo-Jung -- Erwin, Terry -- Di Fiore, Anthony -- Honorio C, Euridice -- Keeling, Helen -- Killeen, Tim J -- Laurance, William F -- Pena Cruz, Antonio -- Pitman, Nigel C A -- Nunez Vargas, Percy -- Ramirez-Angulo, Hirma -- Rudas, Agustin -- Salamao, Rafael -- Silva, Natalino -- Terborgh, John -- Torres-Lezama, Armando -- New York, N.Y. -- Science. 2009 Mar 6;323(5919):1344-7. doi: 10.1126/science.1164033.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Ecology and Global Change, School of Geography, University of Leeds, Leeds LS2 9JT, UK. o.phillips@leeds.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19265020" target="_blank"〉PubMed〈/a〉

Description: Understanding the processes that determine aboveground biomass (AGB) in Amazonian forests is important for predicting the sensitivity of these ecosystems to environmental change and for designing and evaluating dynamic global vegetation models (DGVMs). AGB is determined by inputs from woody productivity (woody NPP) and the rate at which carbon is lost through tree mortality. Here, we test whether two direct metrics of tree mortality (the absolute rate of woody biomass loss and the rate of stem mortality) and/or woody NPP, control variation in AGB among 167 plots in intact forest across Amazonia. We then compare these relationships and the observed variation in AGB and woody NPP with the predictions of four DGVMs. The observations show that stem mortality rates, rather than absolute rates of woody biomass loss, are the most important predictor of AGB, which is consistent with the importance of stand size-structure for determining spatial variation in AGB. The relationship between stem mortality rates and AGB varies among different regions of Amazonia, indicating that variation in wood density and height/diameter relationships also influence AGB. In contrast to previous findings, we find that woody NPP is not correlated with stem mortality rates, and is weakly positively correlated with AGB. Across the four models, basin-wide average AGB is similar to the mean of the observations. However, the models consistently overestimate woody NPP, and poorly represent the spatial patterns of both AGB and woody NPP estimated using plot data. In marked contrast to the observations, DGVMs typically show strong positive relationships between woody NPP and AGB. Resolving these differences will require incorporating forest size structure, mechanistic models of stem mortality and variation in functional composition in DGVMs. This article is protected by copyright. All rights reserved.

Description: Tree height strongly affects estimates of water-use efficiency responses to climate and CO 2 using isotopes Nature Communications, Published online: 18 August 2017; doi:10.1038/s41467-017-00225-z Intrinsic water-use efficiency ( W i ) reconstructions using tree rings often disregard developmental changes in W i as trees age. Here, the authors compare W i across varying tree sizes at a fixed CO 2 level and show that ignoring developmental changes impacts conclusions on trees’ W i responses to CO 2 or climate.

Description: Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Brienen, R J W -- Phillips, O L -- Feldpausch, T R -- Gloor, E -- Baker, T R -- Lloyd, J -- Lopez-Gonzalez, G -- Monteagudo-Mendoza, A -- Malhi, Y -- Lewis, S L -- Vasquez Martinez, R -- Alexiades, M -- Alvarez Davila, E -- Alvarez-Loayza, P -- Andrade, A -- Aragao, L E O C -- Araujo-Murakami, A -- Arets, E J M M -- Arroyo, L -- Aymard C, G A -- Banki, O S -- Baraloto, C -- Barroso, J -- Bonal, D -- Boot, R G A -- Camargo, J L C -- Castilho, C V -- Chama, V -- Chao, K J -- Chave, J -- Comiskey, J A -- Cornejo Valverde, F -- da Costa, L -- de Oliveira, E A -- Di Fiore, A -- Erwin, T L -- Fauset, S -- Forsthofer, M -- Galbraith, D R -- Grahame, E S -- Groot, N -- Herault, B -- Higuchi, N -- Honorio Coronado, E N -- Keeling, H -- Killeen, T J -- Laurance, W F -- Laurance, S -- Licona, J -- Magnussen, W E -- Marimon, B S -- Marimon-Junior, B H -- Mendoza, C -- Neill, D A -- Nogueira, E M -- Nunez, P -- Pallqui Camacho, N C -- Parada, A -- Pardo-Molina, G -- Peacock, J -- Pena-Claros, M -- Pickavance, G C -- Pitman, N C A -- Poorter, L -- Prieto, A -- Quesada, C A -- Ramirez, F -- Ramirez-Angulo, H -- Restrepo, Z -- Roopsind, A -- Rudas, A -- Salomao, R P -- Schwarz, M -- Silva, N -- Silva-Espejo, J E -- Silveira, M -- Stropp, J -- Talbot, J -- ter Steege, H -- Teran-Aguilar, J -- Terborgh, J -- Thomas-Caesar, R -- Toledo, M -- Torello-Raventos, M -- Umetsu, R K -- van der Heijden, G M F -- van der Hout, P -- Guimaraes Vieira, I C -- Vieira, S A -- Vilanova, E -- Vos, V A -- Zagt, R J -- England -- Nature. 2015 Mar 19;519(7543):344-8. doi: 10.1038/nature14283.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Geography, University of Leeds, Leeds LS2 9JT, UK. ; 1] School of Geography, University of Leeds, Leeds LS2 9JT, UK. [2] Geography, College of Life and Environmental Sciences, University of Exeter, Rennes Drive, Exeter EX4 4RJ, UK. ; 1] Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, Berkshire SL5 7PY, UK. [2] School of Marine and Tropical Biology, James Cook University, Cairns, 4870 Queenland, Australia. ; Jardin Botanico de Missouri, Prolongacion Bolognesi Mz.e, Lote 6, Oxapampa, Pasco, Peru. ; Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford OX1 3QK, UK. ; 1] School of Geography, University of Leeds, Leeds LS2 9JT, UK. [2] Department of Geography, University College London, Pearson Building, Gower Street, London WC1E 6BT, UK. ; School of Anthropology and Conservation, Marlowe Building, University of Kent, Canterbury CT1 3EH, UK. ; Servicios Ecosistemicos y Cambio Climatico, Jardin Botanico de Medellin, Calle 73 no. 51 D-14, C.P. 050010, Medellin, Colombia. ; Center for Tropical Conservation, Duke University, Box 90381, Durham, North Carolina 27708, USA. ; Biological Dynamics of Forest Fragment Project (INPA &STRI), C.P. 478, Manaus AM 69011-970, Brazil. ; 1] Geography, College of Life and Environmental Sciences, University of Exeter, Rennes Drive, Exeter EX4 4RJ, UK. [2] National Institute for Space Research (INPE), Av. Dos Astronautas, 1758, Sao Jose dos Campos, Sao Paulo 12227-010, Brazil. ; Museo de Historia Natural Noel Kempff Mercado, Universidad Autonoma Gabriel Rene Moreno, Casilla 2489, Av. Irala 565, Santa Cruz, Bolivia. ; Alterra, Wageningen University and Research Centre, PO Box 47, 6700 AA Wageningen, The Netherlands. ; UNELLEZ-Guanare, Programa de Ciencias del Agro y el Mar, Herbario Universitario (PORT), Mesa de Cavacas, Estado Portuguesa, 3350 Venezuela. ; Biodiversiteit en Ecosysteem Dynamica, University of Amsterdam, Postbus 94248, 1090 GE Amsterdam, The Netherlands. ; 1] Institut National de la Recherche Agronomique, UMR EcoFoG, Campus Agronomique, 97310 Kourou, French Guiana. [2] International Center for Tropical Botany, Department of Biological Sciences, Florida International University, Miami, Florida 33199, USA. ; Universidade Federal do Acre, Campus de Cruzeiro do Sul, Rio Branco, Brazil. ; INRA, UMR 1137 ''Ecologie et Ecophysiologie Forestiere'' 54280 Champenoux, France. ; Embrapa Roraima, Caixa Postal 133, Boa Vista, RR, CEP 69301-970, Brazil. ; Universidad Nacional San Antonio Abad del Cusco, Av. de la Cultura N degrees 733, Cusco, Peru. ; 1] School of Geography, University of Leeds, Leeds LS2 9JT, UK. [2] International Master Program of Agriculture, College of Agriculture and Natural Resources, National Chung Hsing University, Taichung 40227, Taiwan. ; Universite Paul Sabatier CNRS, UMR 5174 Evolution et Diversite Biologique, Batiment 4R1, 31062 Toulouse, France. ; Northeast Region Inventory and Monitoring Program, National Park Service, 120 Chatham Lane, Fredericksburg, Virginia 22405, USA. ; Andes to Amazon Biodiversity Program, Puerto Maldonado, Madre de Dios, Peru. ; Universidade Federal do Para, Centro de Geociencias, Belem, CEP 66017-970 Para, Brazil. ; Universidade do Estado de Mato Grosso, Campus de Nova Xavantina, Caixa Postal 08, CEP 78.690-000, Nova Xavantina MT, Brazil. ; Department of Anthropology, University of Texas at Austin, SAC Room 5.150, 2201 Speedway Stop C3200, Austin, Texas 78712, USA. ; Department of Entomology, Smithsonian Institution, PO Box 37012, MRC 187, Washington DC 20013-7012, USA. ; Cirad, UMR Ecologie des Forets de Guyane, Campus Agronomique, 97310 Kourou, French Guiana. ; 1] School of Geography, University of Leeds, Leeds LS2 9JT, UK. [2] Instituto de Investigaciones de la Amazonia Peruana, Av. A. Jose Quinones km 2.5, Iquitos, Peru. ; World Wildlife Fund, 1250 24th Street NW, Washington DC 20037, USA. ; Centre for Tropical Environmental and Sustainability Science (TESS) and School of Marine and Environmental Sciences, James Cook University, Cairns, Queensland 4878, Australia. ; Instituto Boliviano de Investigacion Forestal, C.P. 6201, Santa Cruz de la Sierra, Bolivia. ; National Institute for Research in Amazonia (INPA), C.P. 478, Manaus, Amazonas, CEP 69011-970, Brazil. ; 1] FOMABO, Manejo Forestal en las Tierras Tropicales de Bolivia, Sacta, Bolivia. [2] Escuela de Ciencias Forestales (ESFOR), Universidad Mayor de San Simon (UMSS), Sacta, Bolivia. ; Universidad Estatal Amazonica, Facultad de Ingenieria Ambiental, Paso lateral km 2 1/2 via Napo, Puyo, Pastaza, Ecuador. ; National Institute for Research in Amazonia (INPA), C.P. 2223, 69080-971, Manaus, Amazonas, Brazil. ; Universidad Autonoma del Beni, Campus Universitario, Av. Ejercito Nacional, Riberalta, Beni, Bolivia. ; 1] Instituto Boliviano de Investigacion Forestal, C.P. 6201, Santa Cruz de la Sierra, Bolivia. [2] Forest Ecology and Forest Management Group, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands. ; 1] Center for Tropical Conservation, Duke University, Box 90381, Durham, North Carolina 27708, USA. [2] The Field Museum, 1400 South Lake Shore Drive, Chicago, Illinois 60605-2496, USA. ; Forest Ecology and Forest Management Group, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands. ; Universidad Nacional de la Amazonia Peruana, Iquitos, Loreto, Peru. ; Instituto de Investigaciones para el Desarrollo Forestal (INDEFOR), Universidad de Los Andes, Facultad de Ciencias Forestales y Ambientales, Conjunto Forestal, C.P. 5101, Merida, Venezuela. ; Iwokrama International Centre for Rainforest Conservation and Development, 77 High Street Kingston, Georgetown, Guyana. ; Museu Paraense Emilio Goeldi, Av. Magalhaes Barata, 376 - Sao Braz, CEP 66040-170, Belem PA, Brazil. ; UFRA, Av. Presidente Tancredo Neves 2501, CEP 66.077-901, Belem, Para, Brazil. ; Museu Universitario, Universidade Federal do Acre, Rio Branco AC 69910-900, Brazil. ; European Commission - DG Joint Research Centre, Institute for Environment and Sustainability, Via Enrico Fermi 274, 21010 Ispra, Italy. ; 1] Naturalis Biodiversity Center, PO Box, 2300 RA, Leiden, The Netherlands. [2] Ecology and Biodiversity Group, Utrecht University, PO Box 80084, 3508 TB Utrecht, The Netherlands. ; Museo de Historia Natural Alcide D'Orbigny, Av. Potosi no 1458, Cochabamba, Bolivia. ; 1] School of Earth and Environmental Science, James Cook University, Cairns, Queensland 4870, Australia. [2] Centre for Tropical Environmental and Sustainability Science (TESS) and School of Marine and Tropical Biology, James Cook University, Cairns, Queensland 4878, Australia. ; 1] Northumbria University, School of Geography, Ellison Place, Newcastle upon Tyne, Newcastle NE1 8ST, UK. [2] University of Wisconsin, Milwaukee, Wisconsin 53202, USA. [3] Smithsonian Tropical Research Institute, Apartado Postal 0843-03092, Panama, Republic of Panama. ; Van der Hout Forestry Consulting, Jan Trooststraat 6, 3078 HP Rotterdam, The Netherlands. ; Universidade Estadual de Campinas, NEPAM, Rua dos Flamboyants, 155- Cidade Universitaria Zeferino Vaz, Campinas, CEP 13083-867, Sao Paulo, Brazil. ; 1] Universidad Autonoma del Beni, Campus Universitario, Av. Ejercito Nacional, Riberalta, Beni, Bolivia. [2] Centro de Investigacion y Promocion del Campesinado, regional Norte Amazonico, C/ Nicanor Gonzalo Salvatierra N degrees 362, Casilla 16, Riberalta, Bolivia. ; Tropenbos International, PO Box 232, 6700 AE Wageningen, The Netherlands.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25788097" target="_blank"〉PubMed〈/a〉

Description: Atmospheric methane (CH 4 ) accounts for ~20% of the total direct anthropogenic radiative forcing by long-lived greenhouse gases. Surface observations show a pause (1999-2006) followed by a resumption in CH 4 growth, which remain largely unexplained. Using a land surface model, we estimate wetland CH 4 emissions from 1993 to 2014 and study the regional contributions to changes in atmospheric CH 4 . Atmospheric model simulations using these emissions, together with other sources, compare well with surface and satellite CH 4 data. Modelled global wetland emissions vary by ±3%/yr (σ = 4.8 Tg), mainly due to precipitation-induced changes in wetland area, but the integrated effect makes only a small contribution to the pause in CH 4 growth from 1999 to 2006. Increasing temperature, which increases wetland area, drives a long-term trend in wetland CH 4 emissions of +0.2%/yr (1999 to 2014). The increased growth post-2006 was partly caused by increased wetland emissions (+3%), mainly from Tropical Asia, Sourthern Africa and Australia.

Description: From 2007 to 2013, the globally-averaged mole fraction of methane in the atmosphere increased by 5.7 ± 1.2 ppb yr -1 . Simultaneously, δ 13 C CH4 (a measure of the 13 C/ 12 C isotope ratio in methane) has shifted to significantly more negative values since 2007. Growth was extreme in 2014, at 12.5 ± 0.4 ppb, with a further shift to more negative values being observed at most latitudes. The isotopic evidence presented here suggests the methane rise was dominated by significant increases in biogenic methane emissions, particularly in the tropics: for example, from expansion of tropical wetlands in years with strongly positive rainfall anomalies, or emissions from increased agricultural sources such as ruminants and rice paddies. Changes in the removal rate of methane by the OH radical have not been seen in other tracers of atmospheric chemistry and do not appear to explain short term variations in methane. Fossil fuel emissions may also have grown, but the sustained shift to more 13 C-depleted values together with its significant interannual variability, and the tropical and Southern Hemisphere loci of post-2007 growth, both indicate fossil fuel emissions have not been the dominant factor driving the increase. A major cause of increased tropical wetland and tropical agricultural methane emissions, the likely major contributors to growth, may be their responses to meteorological change.

Description: Abstract Large‐scale (〉500 km) spatial gradients of precipitation oxygen isotope‐ratios (δ18Op) hold information about the hydrological cycle. They result from the interplay between rainout and evapotranspiration along air‐parcel paths, but these counteracting effects are difficult to disentangle complicating quantification of the effect of land cover change on δ18Op. We show that disentangling can qualitatively be achieved using climate model simulations with a land‐derived precipitation tracer for tropical South America. We then either vary land cover as observed since 1870 or by replacing Amazon forests with bare land to determine the resulting signals. Our results indicate that effects of historically changing land cover on annual mean δ18O isotope‐ratio gradients are small and unlikely detectable, although there is a noticeable signal during the dry season. Furthermore, the effect of changes in water recycling on Amazon δ18Op in paleo‐records may have been overestimated and need reinterpretation.