Site- and species-specific responses of forest growth to climate across the European continent
TL;DR: To evaluate the climate sensitivity of model-based forest productivity estimates using a continental-scale tree-ring network, a network of about 100,000 trees across the globe is analyzed.
Abstract: Aim To evaluate the climate sensitivity of model-based forest productivity estimates using a continental-scale tree-ring network.
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01 Dec 2010
TL;DR: In this article, the authors suggest a reduction in the global NPP of 0.55 petagrams of carbon, which would not only weaken the terrestrial carbon sink, but would also intensify future competition between food demand and biofuel production.
Abstract: Terrestrial net primary production (NPP) quantifies the amount of atmospheric carbon fixed by plants and accumulated as biomass. Previous studies have shown that climate constraints were relaxing with increasing temperature and solar radiation, allowing an upward trend in NPP from 1982 through 1999. The past decade (2000 to 2009) has been the warmest since instrumental measurements began, which could imply continued increases in NPP; however, our estimates suggest a reduction in the global NPP of 0.55 petagrams of carbon. Large-scale droughts have reduced regional NPP, and a drying trend in the Southern Hemisphere has decreased NPP in that area, counteracting the increased NPP over the Northern Hemisphere. A continued decline in NPP would not only weaken the terrestrial carbon sink, but it would also intensify future competition between food demand and proposed biofuel production.
1,780 citations
Max Planck Society1, University of Innsbruck2, Potsdam Institute for Climate Impact Research3, Oeschger Centre for Climate Change Research4, University of Aberdeen5, International Institute of Minnesota6, University of Antwerp7, University of Arizona8, Stockholm University9, ETH Zurich10, Commonwealth Scientific and Industrial Research Organisation11, Centre national de la recherche scientifique12, Aix-Marseille University13, Technical University of Denmark14, University of Potsdam15, University of Alcalá16
TL;DR: It is found that ecosystem responses can exceed the duration of the climate impacts via lagged effects on the carbon cycle, and forests are expected to exhibit the largest net effect of extremes due to their large carbon pools and fluxes, potentially large indirect and lagged impacts, and long recovery time to regain previous stocks.
Abstract: Extreme droughts, heat waves, frosts, precipitation, wind storms and other climate extremes may impact the structure, composition and functioning of terrestrial ecosystems, and thus carbon cycling and its feedbacks to the climate system. Yet, the interconnected avenues through which climate extremes drive ecological and physiological processes and alter the carbon balance are poorly understood. Here, we review the literature on carbon cycle relevant responses of ecosystems to extreme climatic events. Given that impacts of climate extremes are considered disturbances, we assume the respective general disturbance-induced mechanisms and processes to also operate in an extreme context. The paucity of well-defined studies currently renders a quantitative meta-analysis impossible, but permits us to develop a deductive framework for identifying the main mechanisms (and coupling thereof) through which climate extremes may act on the carbon cycle. We find that ecosystem responses can exceed the duration of the climate impacts via lagged effects on the carbon cycle. The expected regional impacts of future climate extremes will depend on changes in the probability and severity of their occurrence, on the compound effects and timing of different climate extremes, and on the vulnerability of each land-cover type modulated by management. Although processes and sensitivities differ among biomes, based on expert opinion, we expect forests to exhibit the largest net effect of extremes due to their large carbon pools and fluxes, potentially large indirect and lagged impacts, and long recovery time to regain previous stocks. At the global scale, we presume that droughts have the strongest and most widespread effects on terrestrial carbon cycling. Comparing impacts of climate extremes identified via remote sensing vs. ground-based observational case studies reveals that many regions in the (sub-)tropics are understudied. Hence, regional investigations are needed to allow a global upscaling of the impacts of climate extremes on global carbon-climate feedbacks.
625 citations
Cites background from "Site- and species-specific response..."
...temperature extreme during the growing season tends to result in enhanced productivity 23 (Esper et al., 2002; Babst et al., 2013), but a positive temperature extreme occurring during 24 Page 76 of 96 Global Change Biology...
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Lamont–Doherty Earth Observatory1, University of East Anglia2, University of Freiburg3, Royal Netherlands Meteorological Institute4, Queen's University Belfast5, University of Padua6, University of Ljubljana7, University of Mainz8, Cornell University9, Stockholm University10, Dresden University of Technology11, University of Barcelona12, United States Department of State13, Deutsches Archäologisches Institut14, Czech University of Life Sciences Prague15, Istanbul University16, University of Gothenburg17, University of Oxford18, University of Pavia19, University of Forestry, Sofia20, Norwegian University of Science and Technology21, University of Arizona22, Nicolaus Copernicus University in Toruń23, University of St Andrews24, Technische Universität München25
TL;DR: Megadroughts reconstructed over north-central Europe in the 11th and mid-15th centuries reinforce other evidence from North America and Asia that droughts were more severe, extensive, and prolonged over Northern Hemisphere land areas before the 20th century, with an inadequate understanding of their causes.
Abstract: Climate model projections suggest widespread drying in the Mediterranean Basin and wetting in Fennoscandia in the coming decades largely as a consequence of greenhouse gas forcing of climate. To place these and other “Old World” climate projections into historical perspective based on more complete estimates of natural hydroclimatic variability, we have developed the “Old World Drought Atlas” (OWDA), a set of year-to-year maps of tree-ring reconstructed summer wetness and dryness over Europe and the Mediterranean Basin during the Common Era. The OWDA matches historical accounts of severe drought and wetness with a spatial completeness not previously available. In addition, megadroughts reconstructed over north-central Europe in the 11th and mid-15th centuries reinforce other evidence from North America and Asia that droughts were more severe, extensive, and prolonged over Northern Hemisphere land areas before the 20th century, with an inadequate understanding of their causes. The OWDA provides new data to determine the causes of Old World drought and wetness and attribute past climate variability to forced and/or internal variability.
429 citations
Chinese Academy of Sciences1, Peking University2, Centre national de la recherche scientifique3, University of Exeter4, Lund University5, National Center for Atmospheric Research6, University of Sheffield7, Oak Ridge National Laboratory8, Boston University9, Max Planck Society10, University of Maryland, College Park11, Princeton University12
TL;DR: The strength of the relationship between the interannual variability of growing season NDVI and temperature (partial correlation coefficient RNDVI-GT) declined substantially between 1982 and 2011 and is mainly observed in temperate and arctic ecosystems.
Abstract: Satellite-derived Normalized Difference Vegetation Index (NDVI), a proxy of vegetation productivity, is known to be correlated with temperature in northern ecosystems. This relationship, however, may change over time following alternations in other environmental factors. Here we show that above 30°N, the strength of the relationship between the interannual variability of growing season NDVI and temperature (partial correlation coefficient RNDVI-GT) declined substantially between 1982 and 2011. This decrease in RNDVI-GT is mainly observed in temperate and arctic ecosystems, and is also partly reproduced by process-based ecosystem model results. In the temperate ecosystem, the decrease in RNDVI-GT coincides with an increase in drought. In the arctic ecosystem, it may be related to a nonlinear response of photosynthesis to temperature, increase of hot extreme days and shrub expansion over grass-dominated tundra. Our results caution the use of results from interannual time scales to constrain the decadal response of plants to ongoing warming.
368 citations
TL;DR: This review starts from the rather well understood processes at the leaf level such as photosynthetic carbon isotope fractionation, leaf water evaporative isotope enrichment and the issue of the isotopic composition of inorganic sources (CO2 and H2O), though it focuses on the less explored 'downstream' processes related to metabolism and transport.
Abstract: The mechanistic understanding of isotope fractionation processes is increasing but we still lack detailed knowledge of the processes that determine the isotopic composition of the tree-ring archive over the long term. Especially with regard to the path from leaf photosynthate production to wood formation, post-assimilation fractionations/processes might cause at least a partial decoupling between the leaf isotope signals that record processes such as stomatal conductance, transpiration and photosynthesis, and the wood or cellulose signals that are stored in the paleophysiological record. In this review, we start from the rather well understood processes at the leaf level such as photosynthetic carbon isotope fractionation, leaf water evaporative isotope enrichment and the issue of the isotopic composition of inorganic sources (CO2 and H2O), though we focus on the less explored 'downstream' processes related to metabolism and transport. We further summarize the roles of cellulose and lignin as important chemical constituents of wood, and the processes that determine the transfer of photosynthate (sucrose) and associated isotopic signals to wood production. We cover the broad topics of post-carboxylation carbon isotope fractionation and of the exchange of organic oxygen with water within the tree. In two case studies, we assess the transfer of carbon and oxygen isotopic signals from leaves to tree rings. Finally we address the issue of different temporal scales and link isotope fractionation at the shorter time scale for processes in the leaf to the isotopic ratio as recorded across longer time scales of the tree-ring archive.
358 citations
Cites background from "Site- and species-specific response..."
...…et al. 1998, Kirdyanov et al. 2003) and more recently for the validation of carbon fluxes in terrestrial ecosystems (Leblanc 1990, Biondi 1999, Babst et al. 2013, Lara et al. 2013), as well as to discern processes involved in the partitioning of photosynthate to various plant growth sinks…...
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References
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TL;DR: In this paper, the authors developed interpolated climate surfaces for global land areas (excluding Antarctica) at a spatial resolution of 30 arc s (often referred to as 1-km spatial resolution).
Abstract: We developed interpolated climate surfaces for global land areas (excluding Antarctica) at a spatial resolution of 30 arc s (often referred to as 1-km spatial resolution). The climate elements considered were monthly precipitation and mean, minimum, and maximum temperature. Input data were gathered from a variety of sources and, where possible, were restricted to records from the 1950–2000 period. We used the thin-plate smoothing spline algorithm implemented in the ANUSPLIN package for interpolation, using latitude, longitude, and elevation as independent variables. We quantified uncertainty arising from the input data and the interpolation by mapping weather station density, elevation bias in the weather stations, and elevation variation within grid cells and through data partitioning and cross validation. Elevation bias tended to be negative (stations lower than expected) at high latitudes but positive in the tropics. Uncertainty is highest in mountainous and in poorly sampled areas. Data partitioning showed high uncertainty of the surfaces on isolated islands, e.g. in the Pacific. Aggregating the elevation and climate data to 10 arc min resolution showed an enormous variation within grid cells, illustrating the value of high-resolution surfaces. A comparison with an existing data set at 10 arc min resolution showed overall agreement, but with significant variation in some regions. A comparison with two high-resolution data sets for the United States also identified areas with large local differences, particularly in mountainous areas. Compared to previous global climatologies, ours has the following advantages: the data are at a higher spatial resolution (400 times greater or more); more weather station records were used; improved elevation data were used; and more information about spatial patterns of uncertainty in the data is available. Owing to the overall low density of available climate stations, our surfaces do not capture of all variation that may occur at a resolution of 1 km, particularly of precipitation in mountainous areas. In future work, such variation might be captured through knowledgebased methods and inclusion of additional co-variates, particularly layers obtained through remote sensing. Copyright 2005 Royal Meteorological Society.
17,977 citations
"Site- and species-specific response..." refers methods in this paper
...0 global temperature and precipitation datasets (Mitchell & Jones, 2005) as a basis and downscaled them to 1-km spatial resolution using the WorldClim database of climate normals based upon the GTOPO30 digital elevation model (Hijmans et al., 2005)....
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...We used the gridded 0.5° ¥ 0.5°CRU TS 3.0 global temperature and precipitation datasets (Mitchell & Jones, 2005) as a basis and downscaled them to 1-km spatial resolution using the WorldClim database of climate normals based upon the GTOPO30 digital elevation model (Hijmans et al., 2005)....
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United States Department of Agriculture1, Chinese Academy of Sciences2, Peking University3, Woods Hole Research Center4, University of Helsinki5, Natural Resources Canada6, University of Leeds7, International Institute for Applied Systems Analysis8, Centre national de la recherche scientifique9, Duke University10, Princeton University11, University of Alaska Fairbanks12, Oak Ridge National Laboratory13
TL;DR: The total forest sink estimate is equivalent in magnitude to the terrestrial sink deduced from fossil fuel emissions and land-use change sources minus ocean and atmospheric sinks, with tropical estimates having the largest uncertainties.
Abstract: The terrestrial carbon sink has been large in recent decades, but its size and location remain uncertain. Using forest inventory data and long-term ecosystem carbon studies, we estimate a total forest sink of 2.4 ± 0.4 petagrams of carbon per year (Pg C year–1) globally for 1990 to 2007. We also estimate a source of 1.3 ± 0.7 Pg C year–1 from tropical land-use change, consisting of a gross tropical deforestation emission of 2.9 ± 0.5 Pg C year–1 partially compensated by a carbon sink in tropical forest regrowth of 1.6 ± 0.5 Pg C year–1. Together, the fluxes comprise a net global forest sink of 1.1 ± 0.8 Pg C year–1, with tropical estimates having the largest uncertainties. Our total forest sink estimate is equivalent in magnitude to the terrestrial sink deduced from fossil fuel emissions and land-use change sources minus ocean and atmospheric sinks.
4,948 citations
"Site- and species-specific response..." refers background in this paper
...The total sink in established forests is currently estimated at 2.4 0.4 Pg C year–1 (Pan et al., 2011) and equals approximately 25% of the current global anthropogenic fossil fuel emissions (Friedlingstein et al., 2010)....
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...4 Pg C year (Pan et al., 2011) and equals approximately 25% of the current global anthropogenic fossil fuel emissions (Friedlingstein et al....
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4,668 citations
Book•
11 Nov 2012
TL;DR: In this paper, a summary of basic dendrochronology, especially its application to Beams from these activities that various statistical methods such as they are covered, is given.
Abstract: This classic title, originally printed in 1976, contains a lucid description and summary of basic dendrochronology, especially its application to Beams from these activities that various statistical methods such as they are covered. They are basically recording a highly, localized analyses possible therefore. Trees grow all places on natural forces. The dendroclimatology that has quickly made climate record initial. This climate remains a glossary of greatest hits to compensate for more than previously estimated. Our study actually does none of natural warm period then sealed to calibrate growth.
4,206 citations
TL;DR: In this paper, a database of monthly climate observations from meteorological stations is constructed and checked for inhomogeneities in the station records using an automated method that refines previous methods by using incomplete and partially overlapping records and by detecting inhomalities with opposite signs in different seasons.
Abstract: A database of monthly climate observations from meteorological stations is constructed. The database includes six climate elements and extends over the global land surface. The database is checked for inhomogeneities in the station records using an automated method that refines previous methods by using incomplete and partially overlapping records and by detecting inhomogeneities with opposite signs in different seasons. The method includes the development of reference series using neighbouring stations. Information from different sources about a single station may be combined, even without an overlapping period, using a reference series. Thus, a longer station record may be obtained and fragmentation of records reduced. The reference series also enables 1961–90 normals to be calculated for a larger proportion of stations. The station anomalies are interpolated onto a 0.5° grid covering the global land surface (excluding Antarctica) and combined with a published normal from 1961–90. Thus, climate grids are constructed for nine climate variables (temperature, diurnal temperature range, daily minimum and maximum temperatures, precipitation, wet-day frequency, frost-day frequency, vapour pressure, and cloud cover) for the period 1901–2002. This dataset is known as CRU TS 2.1 and is publicly available (http://www.cru.uea.ac.uk/). Copyright 2005 Royal Meteorological Society.
4,011 citations