The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Ranga B Myneni - One of the best experts on this subject based on the ideXlab platform.
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comment on drought induced reduction in global terrestrial Net Primary Production from 2000 through 2009
Science, 2011Co-Authors: Arindam Samanta, Marcos Heil Costa, Edson Luis Nunes, Simone A Vieira, Liang Xu, Ranga B MyneniAbstract:Zhao and Running (Reports, 20 August 2010, p. 940) reported a reduction in global terrestrial Net Primary Production (NPP) from 2000 through 2009. We argue that the small trends, regional patterns, and interannual variations that they describe are artifacts of their NPP model. Satellite observations of vegetation activity show no statistically significant changes in more than 85% of the vegetated lands south of 70°N during the same 2000 to 2009 period.
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Comment on “Drought-Induced Reduction in Global Terrestrial Net Primary Production from 2000 Through 2009”
Science, 2011Co-Authors: Arindam Samanta, Marcos Heil Costa, Edson Luis Nunes, Simone A Vieira, Liang Xu, Ranga B MyneniAbstract:Zhao and Running (Reports, 20 August 2010, p. 940) reported a reduction in global terrestrial Net Primary Production (NPP) from 2000 through 2009. We argue that the small trends, regional patterns, and interannual variations that they describe are artifacts of their NPP model. Satellite observations of vegetation activity show no statistically significant changes in more than 85% of the vegetated lands south of 70°N during the same 2000 to 2009 period.
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valuing ecosystem services a shadow price for Net Primary Production
Ecological Economics, 2007Co-Authors: Amy Richmond, Robert K Kaufmann, Ranga B MyneniAbstract:Abstract We analyze the contribution of ecosystem services to GDP and use this contribution to calculate an empirical price for ecosystem services. Net Primary Production is used as a proxy for ecosystem services and, along with capital and labor, is used to estimate a Cobb Douglas Production function from an international panel. A positive output elasticity for Net Primary Production probably measures both marketed and nonmarketed contributions of ecosystems services. The Production function is used to calculate the marginal product of Net Primary Production, which is the shadow price for ecosystem services. The shadow price generally is greatest for developed nations, which have larger technical scalars and use less Net Primary Production per unit output. The rate of technical substitution indicates that the quantity of capital needed to replace a unit of Net Primary Production tends to increase with economic development, and this rate of replacement may ultimately constrain economic growth.
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climate driven increases in global terrestrial Net Primary Production from 1982 to 1999
Science, 2003Co-Authors: Ramakrishna R. Nemani, Ranga B Myneni, Charles D Keeling, Hirofumi Hashimoto, William M Jolly, Stephen C Piper, Compton J Tucker, Steven W RunningAbstract:Recent climatic changes have enhanced plant growth in northern mid-latitudes and high latitudes. However, a comprehensive analysis of the impact of global climatic changes on vegetation productivity has not before been expressed in the context of variable limiting factors to plant growth. We present a global investigation of vegetation responses to climatic changes by analyzing 18 years (1982 to 1999) of both climatic data and satellite observations of vegetation activity. Our results indicate that global changes in climate have eased several critical climatic constraints to plant growth, such that Net Primary Production increased 6% (3.4 petagrams of carbon over 18 years) globally. The largest increase was in tropical ecosystems. Amazon rain forests accounted for 42% of the global increase in Net Primary Production, owing mainly to decreased cloud cover and the resulting increase in solar radiation.
Fridolin Krausmann - One of the best experts on this subject based on the ideXlab platform.
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human appropriation of Net Primary Production patterns trends and plaNetary boundaries
Annual Review of Environment and Resources, 2014Co-Authors: Helmut Haberl, Fridolin KrausmannAbstract:Economic and population growth result in increasing use of biophysical resources, including land and biomass. Human activities influence the biological productivity of land, altering material and energy flows in the biosphere. The human appropriation of Net Primary Production (HANPP) is an integrated socioecological indicator quantifying effects of human-induced changes in productivity and harvest on ecological biomass flows. We discuss how HANPP is defined, measured, and interpreted. Two principal approaches for constructing HANPP assessments exist: (a) In an area-specific approach, HANPP serves as an indicator of land-use intensity, gauging impacts on terrestrial ecosystems in a defined area; and (b) the consumption-based “embodied HANPP” approach allows assessment of impacts related to individual products or the aggregate consumption of nation-states. The HANPP framework can help to estimate upper limits for the biosphere's capacity to provide humanity with biomass for food, fiber, and bioenergy and to...
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global human appropriation of Net Primary Production doubled in the 20th century
Proceedings of the National Academy of Sciences of the United States of America, 2013Co-Authors: Fridolin Krausmann, Helmut Haberl, Simone Gingrich, Alberte Bondeau, Veronika Gaube, Christian Lauk, Christoph Plutzar, Timothy D SearchingerAbstract:Global increases in population, consumption, and gross domestic product raise concerns about the sustainability of the current and future use of natural resources. The human appropriation of Net Primary Production (HANPP) provides a useful measure of human intervention into the biosphere. The productive capacity of land is appropriated by harvesting or burning biomass and by converting natural ecosystems to managed lands with lower productivity. This work analyzes trends in HANPP from 1910 to 2005 and finds that although human population has grown fourfold and economic output 17-fold, global HANPP has only doubled. Despite this increase in efficiency, HANPP has still risen from 6.9 Gt of carbon per y in 1910 to 14.8 GtC/y in 2005, i.e., from 13% to 25% of the Net Primary Production of potential vegetation. Biomass harvested per capita and year has slightly declined despite growth in consumption because of a decline in reliance on bioenergy and higher conversion efficiencies of Primary biomass to products. The rise in efficiency is overwhelmingly due to increased crop yields, albeit frequently associated with substantial ecological costs, such as fossil energy inputs, soil degradation, and biodiversity loss. If humans can maintain the past trend lines in efficiency gains, we estimate that HANPP might only grow to 27–29% by 2050, but providing large amounts of bioenergy could increase global HANPP to 44%. This result calls for caution in refocusing the energy economy on land-based resources and for strategies that foster the continuation of increases in land-use efficiency without excessively increasing ecological costs of intensification.
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Human Appropriation of Net Primary Production, Stocks and Flows of Carbon, and Biodiversity
Ecosystem Services and Carbon Sequestration in the Biosphere, 2013Co-Authors: Helmut Haberl, Simone Gingrich, Thomas Kastner, Fridolin KrausmannAbstract:The human appropriation of Net Primary Production (HANPP) is an integrated socioecological indicator of land-use intensity. HANPP is defined as the alteration of the availability of biomass in ecosystems resulting from (1) changes in Net Primary Production (NPP) induced by current or past land use and (2) biomass harvest. In this chapter we discuss how HANPP can be extended with data on carbon (C) stocks in biota and soils to forge an integrated stock-flow account of C in ecosystems. Using comprehensive data for Austria in the period of 1830–2000 as an example, we illustrate the usefulness of such accounts to improve our understanding of human impacts on the stocks and flows of C in ecosystems – an important component of the human alteration of the global C cycle. Austria’s agrarian-industrial transition was accompanied not only by a tremendous growth of fossil-fuel related C flows, but also by profound changes in C stocks and flows in biota and soils. Fossil-fuel related emissions increased from almost zero to 14.6 Tg C year−1 while, at the same time, a land-based C sink of 2.6 Tg C year−1 emerged. These trends were related causally because the use of fossil fuels in agriculture supported agricultural intensification which helped raising yields. This in return resulted in shrinking farmland and growing forest (as well as settlement) areas. Stocking densities in forests grew as well. While the strength of an integrated C accounting system is being analyzed and discussed, we also review the current state of knowledge regarding potential interrelations of HANPP and biodiversity.
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human appropriation of Net Primary Production
Science, 2002Co-Authors: Helmut Haberl, Fridolin Krausmann, Niels SchulzAbstract:The fraction of total plant growth or Net Primary Production (NPP) appropriated by humans, often referred to as human appropriation of Net Primary Production (HANPP), is among the most widely used measures to assess the “human domination of Earth's ecosystems” ([1][1]). S. Rojstaczer et al. (“
Jingyun Fang - One of the best experts on this subject based on the ideXlab platform.
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relationship between variability in aboveground Net Primary Production and precipitation in global grasslands
Geophysical Research Letters, 2008Co-Authors: Yuanhe Yang, Jingyun Fang, Wei WangAbstract:[1] Aboveground Net Primary Production (ANPP) is strongly correlated with annual precipitation (AP) in grassland ecosystems. However, the relationship between the interannual variation in ANPP and the variability in precipitation remains controversial. In this study, we used long-term data of biomass and precipitation from 118 sites across global grasslands to examine the relationship between variability in ANPP and AP. Our results showed that ANPP increased with precipitation, but leveled off in humid regions, and that increased variation in precipitation led to an increase in the variability in ANPP. The relative ANPP maxima significantly increased with relative AP maxima and the relative ANPP minima also positively correlated with relative AP minima. These suggest that the fluctuations in precipitation can alter the growth of grasslands, which should be incorporated into the prediction and modeling of climate changes.
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increasing Net Primary Production in china from 1982 to 1999
Frontiers in Ecology and the Environment, 2003Co-Authors: Jingyun Fang, Shilong Piao, Christopher B Field, Liming Zhou, Changhui PengAbstract:We used a simple process model and satellite data to explore trends in China’s terrestrial Net Primary Production (NPP). We found that the country’s terrestrial NPP increased by 18.7% from 1982 to 1999. Evidence for this major increase also came from crop yields and forest inventory surveys, and much of it appeared to be the result of a lengthening of the growing season. Plant growth also increased during the middle of the growing season, but to a lesser extent. Historical NPP trends indicate a great deal of spatial heterogeneity, increasing significantly over an area covering 30.8% of China during the past 18 years, but decreasing in areas undergoing rapid urbanization.
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interannual variability in Net Primary Production and precipitation
Science, 2001Co-Authors: Jingyun Fang, Shilong Piao, Zhiyao Tang, Changhui Peng, Wei JiAbstract:Knapp and Smith (1) suggested that interannual variability in aboveground Net Primary Production (ANPP) is not related to fluctuations in precipitation, based on analysis of data from 11 Long-Term Ecological Research sites across North America. This finding, if applicable to other regions, is crucial to climate change research, because it may necessitate revisions of projections of ecosystem responses to climate change (2, 3). To examine the relationship between variability in Net Primary Production (NPP) and precipitation at a broad scale, a longterm normalized difference vegetation index (NDVI) data set derived from the Advanced Very High Resolution Radiometer (AVHRR) of the National Oceanic and Atmospheric Administration (NOAA), coupled with a historical climate data set, should constitute a useful and powerful data source, because NDVI data are strongly correlated with terrestrial NPP and are frequently used as NPP predictors (4, 5). We used an annual mean NDVI data set over China to quantify temporal NPP variability relative to precipitation variation, and used coefficient of variation (CV) to express the magnitude of interannual variability in NDVI and precipitation. We then calculated CVs of these two variables for each pixel, with a resolution of 0.1° latitude by 0.1° longitude, for five biome groups across China—forest, grassland, desert, alpine vegetation, and cropland (6 )—using 1982 to 1999 NDVI and precipitation data compiled in China (7 ). We assumed that interannual variability in NDVI or NPP was related to temporal variability in precipitation if the correlation between CVs for NDVI or NPP and precipitation were identified as statistically significant. The CV value of NDVI for these five biome groups showed a large spatial variation, with a mean CV of 8.3% for the forest biome group, 10.4% for grasslands, 24.6% for desert areas, 12.7% for alpine vegetation, and 9.3 % for cropland. The largest variation occurred in the desert bi
Stith T Gower - One of the best experts on this subject based on the ideXlab platform.
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Net Primary Production and carbon allocation patterns of boreal forest ecosystems
Ecological Applications, 2001Co-Authors: Stith T Gower, Olga N Krankina, R J Olson, M J Apps, Sune Linder, Chuankuan WangAbstract:The three objectives of this paper were: to summarize Net Primary Production (NPP) and carbon allocation patterns for boreal forests, to examine relationships between climatic and biological variables and NPP, and to examine carbon allocation coefficients for all boreal forests or types of boreal forests that can be used to estimate NPP from easily measured components of NPP. Twenty-four Class I stands (complete NPP budgets) and 45 Class II boreal forest stands (aboveground NPP [NPPA] and budget only) were identified. The geographic distribution of the Class I stands was not uniform; 46% of the stands were from two studies in North America, and only one stand was from the important larch forests of Eurasia. Total (above- and belowground) Net Primary Production (NPPT) ranged from 52 to 868 g C·m−2·yr−1 and averaged 424 g C·m−2·yr−1. NPPA was consistently larger for deciduous than for evergreen boreal forests in each of the major boreal regions, especially for boreal forests in Alaska. Belowground Net prima...
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aboveground Net Primary Production decline with stand age potential causes
Trends in Ecology and Evolution, 1996Co-Authors: Stith T Gower, Ross E Mcmurtrie, Danuse MurtyAbstract:Abstract Aboveground Net Primary Production (ANPP) commonly reaches a maximum in young forest stands and decreases by 0–76% as stands mature. However, the mechanism(s) responsible for the decline are not well understood. Current hypotheses for declining ANPP with stand age include: (1) an altered balance between photosynthetic and respiring tissues, (2) decreasing soil nutrient availability, and (3) increasing stomatal limitation leading to reduced photosynthetic rates. Recent empirical and modeling studies reveal that mechanisms (2) and (3) are largely responsible for age-related decline in ANPP for forests in cold environments. Increasing respiratory costs appear to be relatively unimportant in explaining declining productivity in ageing stands.
William J Parton - One of the best experts on this subject based on the ideXlab platform.
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regional and temporal variation in Net Primary Production and nitrogen mineralization in grasslands
Ecology, 1997Co-Authors: Ingrid C Burke, William K. Lauenroth, William J PartonAbstract:Spatial variability that occurs at large scales has long been used by ecologists as a tool to examine the controls over ecosystem structure and function. Correlations of control variables such as climatic factors and response variables such as vegetation and soil carbon storage across broad regions have played a crucial role in predicting the response of ecosystems to global climate change. Despite the importance of these large-scale space-for-time substitutions, there are substantial limitations. One of these limitations is that many of the possible control factors covary with one another, and only some of the important control factors actually exist in large-scale databases. Thus, the true proximal controls may be difficult to identify. A second limitation is that models of spatial variability may not be appropriately applied to temporal variability. In this paper, we utilize a new approach to determine the extent to which N availability may constrain aboveground Primary productivity in the Central Grassland region of the U.S. The strong relationship between average annual Primary Production and average annual precipitation found in spatial patterns in ecosystems globally has often been interpreted as evidence of a fundamental water limitation. However, temporal variation in annual aboveground Net Primary Production (ANPP) indicates that other factors constrain Production. We generated a spatial and temporal database for annual aboveground Net Primary Production and annual Net N mineralization by linking a database of input variables (precipitation, temperature, and soils) with predictive models. We generated independent data sets of aboveground Net Primary Production and Net N mineralization by using regression models to predict aboveground Net Primary Production, and the Century model to simulate Net N mineralization. Our analyses indicate that Net Primary Production and Net N mineralization both increase with mean annual precipitation; thus, it is not possible to separate the extent to which ANPP is controlled by water or N availability. Nitrogen use efficiency (NUE) increased with increasing precipitation across the region. Aboveground Net Primary Production decreased with increasing temperature across the region, while N mineralization increased slightly, leading to decreasing (NUE) with increasing temperature. At high precipitation levels, aboveground Net Primary Production increased and N mineralization decreased slightly with increasing soil fineness. Nitrogen use efficiency generally increased with increasing pools of soil organic matter, likely because in grasslands, the proportion of recalcitrant organic matter increases with the total organic matter pools. A comparison of interannual variation in Net N mineralization with average spatial variation indicated a high degree of inertia in the response of N availability to precipitation levels. Our simulation results as well as field results of Lauenroth and Sala (1992) raise important questions about the applicability of space-for-time substitutions when dealing with ecosystem function. The structure of the systems appears to provide important constraints on the temporal variability that are not evident in an analysis of spatial variability.