Terrestrial Net Primary Productivity Research Articles

Exploring global patterns of net primary production carbon supply and demand using satellite observations and statistical data

A unique combination of satellite and socioeconomic data were used to explore the relationship between human consumption and the carbon cycle. The amount of Earth's net primary production (NPP) required to support human activities is a powerful measure of the aggregate impact on the biosphere and indicator of societal vulnerability to climate change. Biophysical models were applied to consumption data to estimate the annual amount of Earth's terrestrial net primary production humans require for food, fiber (including fabrication) and fuel using the same modeling architecture as satellite‐supported NPP measurements. The amount of NPP required was calculated on a per capita basis and projected onto a global map of population to create a spatially explicit map of NPP‐carbon “demand” in units of elemental carbon. NPP demand was compared to a map of Earth's average annual net primary production or “supply” created using 17 years (1982–1998) of AVHRR vegetation index to produce a geographically accurate balance sheet of NPP‐carbon “supply” and “demand” for the globe. Globally, humans consume 20% of Earth's total net primary production on land. Regionally, the NPP‐carbon balance percentage varies from 6% to over 70% and locally from near 0% to over 30,000% in major urban areas. Scenarios modeling the impact of per capita consumption, population growth, and technology suggest that NPP demand is likely to increase substantially in the next 40 years despite better harvesting and processing efficiencies.

Temporal variations and distribution of carbon stocks in aboveground biomass of radiata pine and maritime pine pure stands under different silvicultural alternatives

In recent years there has been considerable interest in evaluating carbon budgets in forests because of the importance of these ecosystems as carbon sources and sinks. Quantifying forest net primary production (NPP) is critical to understanding the global carbon cycle because forests are responsible for a large portion of the total terrestrial NPP. The present study provides information about the temporal and spatial dynamics of carbon (C) stored in aboveground tree biomass in even-aged, pure stands of maritime pine and radiata pine managed under different silvicultural regimes in northwest Spain. Carbon budgets (storage calculations) for tree biomass provide useful information for characterizing forests as important C sinks and allow assessment of the potential effects of harvesting and logging residue management on forest C status. Stand dynamic growth models were used to estimate the amount of C accumulated in the remaining stand and the amount removed in thinning treatments throughout the whole rotation. For radiata pine, carbon sequestration in total aboveground tree biomass at stand level in the whole rotation (thinnings and clear-cutting at 30 years) ranged from 3.4 Mg ha −1 per year (the lowest initial stocking density, the worst site quality and 35% of thinning intensity) to 5.9 Mg ha −1 per year (the highest initial stocking density, the best site quality and 15% of thinning intensity). For maritime pine, the amount of tree biomass at stand level was significantly lower than in radiata pine stands, and mean annual carbon storage ranged from 2.3 to 4.6 Mg ha −1 per year for the same rotation length. The total aboveground and stem wood biomass C pools in these stands can be increased by increasing the rotation age and site quality and decreasing thinning intensity. Selection of the best site qualities, reduction of the thinning intensity and perhaps extension of the rotation length are therefore possible strategies for sustainable management of pine stands in Spain when the main objective is biomass production and C sequestration.

Satellite Remote Sensing of Terrestrial Net Primary Production for the Pan-Arctic Basin and Alaska

We applied a terrestrial net primary production (NPP) model driven by satellite remote sensing observations of vegetation properties and daily surface meteorology from a regional weather forecast model to assess NPP spatial and temporal variability for the pan-Arctic basin and Alaska from 1982 to 2000. Our results show a general decadal trend of increasing NPP for the region of approximately 2.7%, with respective higher (3.4%) and lower (2.2%) rates for North America and Eurasia. NPP is both spatially and temporally dynamic for the region, driven largely by differences in productivity rates among major biomes and temporal changes in photosynthetic canopy structure and spring and summer air temperatures. Mean annual NPP for boreal forests was approximately 3 times greater than for Arctic tundra on a unit area basis and accounted for approximately 55% of total annual carbon sequestration for the region. The timing of growing season onset inferred from regional network measurements of atmospheric CO2 drawdown in spring was inversely proportional to annual NPP calculations. Our findings indicate that recent regional warming trends in spring and summer and associated advances in the growing season are stimulating net photosynthesis and annual carbon sequestration by vegetation at high latitudes, partially mitigating anthropogenic increases in atmospheric CO2. These results also imply that regional sequestration and storage of atmospheric CO2 is being altered, with potentially greater instability and acceleration of the carbon cycle at high latitudes.

The terrestrial NPP simulations in China since Last Glacial Maximum

Based on Atmosphere-Vegetation Interaction Model (AVIM), the magnitude and spatial distribution of terrestrial net primary productivity (NPP) in China is simulated during three different geological eras, Last Glacial Maximum (LGM), Mid-Holocene (MH) and the present. The simulation shows that the glacial-interglacial variation of East Asian summer monsoon in China is the key factor affecting the NPP change. During the three eras, mean NPPs are 208 g/m2.a, 409 g/m2.a, and 355 g/m2.a. The total NPPs are 2.05 Pg/a, 3.89 Pg/a and 3.33 Pg/a, respectively. The terrestrial NPP in China during warm-humid climate is larger than that during cold-arid eras, and the correlation analysis between NPP and climate factors suggests that temperature is the primary factor affecting the terrestrial NPP during 21 kaBP (LGM), and for 6 kaBP (MH) and the present the primary factor is precipitation.

Changes in vegetation net primary productivity from 1982 to 1999 in China

Terrestrial net primary production (NPP) has been a central focus of ecosystem science in the past several decades because of its importance to the terrestrial carbon cycle and ecosystem processes. Modeling studies suggest that terrestrial NPP has increased in the northern middle and high latitudes in the past 2 decades, and that such increase has exhibited seasonal and spatial variability, but there are few detailed studies on the temporal and spatial patterns of NPP trend over time in China. Here we present the trends in China's terrestrial NPP from 1982 to 1999 and their driving forces using satellite‐derived NDVI (Normalized Difference Vegetation Index), climate data, and a satellite‐based carbon model, CASA (Carnegie ‐Ames‐Stanford Approach). The majority of China (86% of the study area) has experienced an increase in NPP during the period 1982–1999, with an annual mean increase rate of 1.03%. This increase was resulted primarily from plant growth in the middle of the growing season (June to August) (about 43.2%), followed by spring (33.7%). At the national and biome levels, the relative increase is largest in spring (March–May), indicating an earlier onset of the growing season. The changes in the phase of China's seasonal NPP curve may primarily be the result of advanced growing season (earlier spring) and enhanced plant growth in summer. During the past 2 decades the amplitude of the seasonal curve of NPP has increased and the annual peak NPP has advanced. Historical NPP trends also indicated a high degree of spatial heterogeneity, coupled with regional climate variations, agricultural practices, urbanization, and fire disturbance.

What is NPP? Inconsistent accounting of respiratory fluxes in the definition of net primary production

Primary production represents a globally important flux of carbon between the atmosphere and the biosphere. From an ecological perspective, it measures the rate at which solar energy is stored by plants as organic matter, and is therefore a measure of the rate at which solar energy is captured and made available to the rest of the food chain (Odum 1971). From a biogeochemical perspective, primary production provides links between the biosphere and the climate system through the global cycling of C, water and nutrients (Roy et al . 2001). Gross primary production (GPP) is the total amount of C assimilated by plants within a given area over a specified timeframe. (Here GPP refers to the total C fixed by photosynthesis, minus the C lost by photorespiration. We have adopted the convention of specifying productivity in units of C mass per unit ground area per unit time, although we could have alternatively used units of total biomass, or energy: Odum 1971.) Net primary production (NPP) is GPP less the flux of autotrophic respiration of assimilate used for the plant’s own metabolism ( R ), therefore:

Soil animals alter plant litter diversity effects on decomposition

Most of the terrestrial net primary production enters the decomposer system as dead organic matter, and the subsequent recycling of C and nutrients are key processes for the functioning of ecosystems and the delivery of ecosystem goods and services. Although climatic and substrate quality controls are reasonably well understood, the functional role of biodiversity for biogeochemical cycles remains elusive. Here we ask how altering litter species diversity affects species-specific decomposition rates and whether large litter-feeding soil animals control the litter diversity-function relationship in a temperate forest ecosystem. We found that decomposition of a given litter species changed greatly in the presence of litters from other cooccurring species despite unaltered climatic conditions and litter chemistry. Most importantly, soil fauna determined the magnitude and direction of litter diversity effects. Our data show that litter species richness and soil fauna interactively determine rates of decomposition in a temperate forest, suggesting a combination of bottom-up and top-down controls of litter diversity effects on ecosystem C and nutrient cycling. These results provide evidence that, in ecosystems supporting a well developed soil macrofauna community, animal activity plays a fundamental role for altered decomposition in response to changing litter diversity, which in turn has important implications for biogeochemical cycles and the long-term functioning of ecosystems with ongoing biodiversity loss.

Variability in Springtime Thaw in the Terrestrial High Latitudes: Monitoring a Major Control on the Biospheric Assimilation of Atmospheric CO2with Spaceborne Microwave Remote Sensing

Abstract Evidence is presented from the satellite microwave remote sensing record that the timing of seasonal thawing and subsequent initiation of the growing season in early spring has advanced by approximately 8 days from 1988 to 2001 for the pan-Arctic basin and Alaska. These trends are highly variable across the region, with North America experiencing a larger advance relative to Eurasia and the entire region. Interannual variability in the timing of spring thaw as detected from the remote sensing record corresponded directly to seasonal anomalies in mean atmospheric CO2 concentrations for the region, including the timing of the seasonal draw down of atmospheric CO2 from terrestrial net primary productivity (NPP) in spring, and seasonal maximum and minimum CO2 concentrations. The timing of the seasonal thaw for a given year was also found to be a significant (P < 0.01) predictor of the seasonal amplitude of atmospheric CO2 for the following year. These results imply that the timing of seasonal thawing...

Remote sensing of crop production in China by production efficiency models: models comparisons, estimates and uncertainties

Regional estimates or prediction of crop production is critical for many applications such as agricultural lands management, food security warning system, food trade policy and carbon cycle research. Remote sensing offers great potential for regional production monitoring and estimates, yet uncertainties associated with are rarely addressed. Moreover, although crops are one of critical biomes in global carbon cycle research, few evidences are available on the performance of global models of terrestrial net primary productivity (NPP) in estimating regional crop NPP. In this study, we use high quality weather and crop data to calibrate model parameter, validate and compare two kinds of remote sensing based production efficiency models, i.e. the Carnegie-Ames-Stanford-Approach (CASA) and Global Production Efficiency Model Version 2.0 (GLO-PEM2), in estimating maize production across China. Results show that both models intend to underestimate maize yields, although they also overestimate maize yields much at some regions. There are no significant differences between the results from CASA and GLO-PEM2 models in terms of both estimated production and spatial pattern. CASA model simulates better in the areas with dense crop and weather data for calibration. Otherwise GLO-PEM2 model does better. Whether the water soil-moisture down-regulator is used or not should depend on the percent of irrigation lands at the regions. The improved and validated models can be used for many applications. Further improvement can be expected by increasing remote sensing image resolution and the number of surface data stations.

The role of climate variability in the inter-annual variation of terrestrial net primary production (NPP)

Eleven years data set of global net primary production (NPP) and long-term climatic and land use data were used to explore the patterns of inter-annual variability of terrestrial NPP in relation to potential causal factors. Global anomalies in temperature, precipitation and cloud cover were found to significantly contribute in different ways and magnitudes to the variability of NPP of global ecosystems particularly forests and grasslands. El Niño/La Niña events represented an important factor affecting forests, woodlands and grasslands while deforestation was found to largely contribute to the NPP variability of tropical forests. Regionally, NPP variability is related to variation of precipitation in the tropics but is related to both variation and annual mean of temperature and cloud cover in the mid-northern latitudes. We hypothesized that the increase in variability of potential causal factor(s) will provoke more declines of NPP in the tropics but will yield more pulses or at least maintain a mean NPP in the mid-northern latitudes.

The global socioeconomic energetic metabolism as a sustainability problem

This paper discusses sustainability problems related to socioeconomic energy flows based upon the societal metabolism approach. Contrary to conventional energy statistics that only include energy used in technical devices, this approach considers all kinds of energy flows related to human societies, including nutritional energy flows of humans and domesticated animals. Based upon human population data and data on the pro capite energy metabolism of hunter-gatherers and agricultural societies as well as on statistical data on industrial energy flows a time series of the global socioeconomic energetic metabolism for the last 10 6 years and a scenario for the next 50 years is derived. These estimates show that the total energy input of mankind has risen by several orders of magnitude since the Neolithic revolution about 10,000 years ago. Whereas the energy input of agricultural societies prior to the advent of industrial societies about 200–300 years ago did not exceed 5% of global terrestrial net primary productivity (NPP), humanity's energy input currently amounts to about 30% of global terrestrial NPP and is likely to surpass 50% in about 2050. This shows that the sheer magnitude of human-induced flows is historically unprecedented and poses at least two closely interrelated sustainability challenges: (1) a reduction of energy available to ecosystem processes that can be assessed using the concept of ‘human appropriation of net primary productivity’ and (2) the changes in the global carbon cycle resulting from land-use change and fossil-energy combustion.

An analysis of some diverse approaches to modelling terrestrial net primary productivity

We inter-compare the mathematical formulation of ten models of terrestrial net primary productivity (NPP) and their functional responses to temperature ( T), carbon dioxide (CO 2), soil water ( W) and photosynthetically active radiation (PAR). The models span a broad spectrum of complexity of approaches from the original, empirical Miami model, through β-factor, and global-average box models, to the dynamic global vegetation models (DGVMs) TRIFFID and BIOME3. Five of the models separate photosynthesis and respiration, although only three directly consider biochemistry. Equations for all the models are given in a complete, compact, standardized format. NPP responses to temperature differ markedly: β-factor models show only a tiny increase with temperature, empirical models predict a modest S-shaped response saturating above 35 °C (a surrogate for drought effects), biochemical and quasi-biochemical models show a peaked response with an optimum in the range 15–25 °C except for DEMETER (<10 °C). Qualitative differences in whether respiration exhibits a peaked or exponential response to temperature have only a modest effect on NPP. The CO 2 response of NPP is qualitatively similar in all but one model that misrepresents it. Where a water stress response of NPP is represented, it is saturating in all but the same model, where NPP declines under high soil moisture. Where represented, the PAR response of NPP is saturating, but the saturation point differs considerably. When responses to two environmental variables are combined, the second variable typically just scales the response to the first. In biochemical models, the temperature optimum of NPP increases with CO 2, and it also increases noticeably with PAR in TRIFFID and a derivative of it. Where different plant functional types (PFTs) are represented, C 4 grasses have the greatest maximum NPP at a higher optimum temperature than any C 3 PFT. Boreal, needle-leaf trees generally have the lowest NPP. Additional uncertainties in modelling respiration, stomatal conductance, light-use efficiency, and scaling to the canopy level are discussed. We suggest that a concerted effort to standardize definitions, notation, units and PFTs would add a degree of transparency that is currently lacking in NPP modelling.

Remotely Sensed Interannual Variations and Trends in Terrestrial Net Primary Productivity 1981?2000

Spatial and temporal variations in net primary production (NPP) are of great importance to ecological studies, natural resource management, and terrestrial carbon sink estimates. However, most of the existing estimates of interannual variation in NPP at regional and global scales were made at coarse resolutions with climate-driven process models. In this study, we quantified global NPP variation at an 8 km and 10-day resolution from 1981 to 2000 based on satellite observations. The high resolution was achieved using the GLObal Production Efficiency Model (GLO-PEM), which was driven with variables derived almost entirely from satellite remote sensing. The results show that there was an increasing trend toward enhanced terrestrial NPP that was superimposed on high seasonal and interannual variations associated with climate variability and that the increase was occurring in both northern and tropical latitudes. NPP generally decreased in El Nino season and increased in La Nina seasons, but the magnitude and spatial pattern of the response varied widely between individual events. Our estimates also indicate that the increases in NPP during the period were caused mainly by increases in atmospheric carbon dioxide and precipitation. The enhancement of NPP by warming was limited to northern high latitudes (above 50°N); in other regions, the interannual variations in NPP were correlated negatively with temperature and positively with precipitation.

Broad‐scale geographical patterns in local stream insect genera richness

Comprehensive global studies of stream invertebrate assemblages are rare and have produced contradictory results. To address this shortcoming, we compiled data from 495 published estimates of local genera richness for three orders of stream‐dwelling insects (Ephemeroptera, Plecoptera, Trichoptera) from throughout the world and used these data to describe global geographic patterns in stream insect genera richness and to address two questions: 1) does local stream insect richness vary more with regional historical factors or with local ecological factors?, and 2) to what extent have streams converged in the number of taxa they support? Maximum genera richness varied sharply across the range of latitude examined from the south to north poles for all three orders of aquatic insects. Ephemeroptera richness showed 3 peaks (∼30°S, 10°N, and 40°N) with highest richness near 5–10°N and 40°N latitude. Plecoptera richness was distinctly highest at ∼40°N latitude with a similar peak at 40°S latitude. Trichoptera richness showed less latitudinal variation than the other taxa but was slightly higher near the equator and at 40°N and S latitude than at other latitudes. Genera richness generally declined with increasing elevation, except for Plecoptera. Maximum genera richness increased steadily with a measure of regional terrestrial net primary production and declined sharply with a measure of hydrologic disturbance for all orders. Richness varied widely among both biogeographical realms and biomes, although ca 2 times as much variation in richness was associated with biome as biogeographic realm. Richness for each order was highest in different biogeographic realms, but all orders had highest richness in broadleaf forest biomes. These latter results imply that spatial variation in local richness of stream insects is more strongly affected by contemporary ecological factors than by historical biogeography and that maintenance of intact forested landscapes may be critical to the conservation of stream invertebrate faunas.

Spatial variability of aboveground net primary production for a forested landscape in northern Wisconsin

Quantifying forest net primary production (NPP) is critical to understanding the global carbon cycle because forests are responsible for a large portion of the total terrestrial NPP. The objectives of this study were to measure above ground NPP (NPPA) for a land surface in northern Wisconsin, examine the spatial patterns of NPPA and its components, and correlate NPPA with vegetation cover types and leaf area index. Mean NPPA for aspen, hardwoods, mixed forest, upland conifers, nonforested wetlands, and forested wetlands was 7.8, 7.2, 5.7, 4.9, 5.0, and 4.5 t dry mass·ha–1·year–1, respectively. There were significant (p = 0.01) spatial patterns in wood, foliage, and understory NPP components and NPPA (p = 0.03) when the vegetation cover type was included in the model. The spatial range estimates for the three NPP components and NPPA differed significantly from each other, suggesting that different factors are influencing the components of NPP. NPPA was significantly correlated with leaf area index (p = 0.01) for the major vegetation cover types. The mean NPPA for the 3 km × 2 km site was 5.8 t dry mass·ha–1·year–1.

Increasing Net Primary Production in China from 1982 to 1999

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.

Increasing net primary production in China from 1982 to 1999

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.

Climate-driven increases in global terrestrial net primary production from 1982 to 1999.

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.

Climate dependence of the CO2 fertilization effect on terrestrial net primary production

Climate dependence of the CO2 fertilization effect on terrestrial net primary production

The temporal and spatial patterns of terrestrial net primary productivity in China

In this paper, we use CEVSA, a process-based model, which has been validated on regional and global scales, to explore the temporal and spatial patterns of Net Primary Productivity (NPP) and its responses to interannual climate fluctuations in China’s terrestrial ecosystems over the period 1981–1998. The estimated results suggest that, in this study period, the averaged annual total NPP is about 3.09 Gt C/yr1 and average NPP is about 342 g C/m2. The results also showed that the precipitation was the key factor determining the spatial distribution and temporal trends of NPP. Temporally, the total NPP exhibited a slowly increasing trend. In some ENSO years (e.g. 1982, 1986, 1997) NPP decreased clearly compared to the previous year, but the relationship between ENSO and NPP is complex due to the integrated effects of monsoons and regional differentiation. Spatially, the relatively high NPP occurred at the middle high latitudes, the low latitudes and the lower appeared at the middle latitudes. On national scale, precipitation is the key control factor on NPP variations and there exists a weak correlation between NPP and temperature, but regional responses are greatly different.