Primary Productivity In China Research Articles

Assessing the impact of the urbanization process on net primary productivity in China in 1989–2000

Urban development affects the material circulation and energy flow of ecosystems, thereby affecting the Net Primary Productivity (NPP). The loss of NPP due to urban expansion was calculated integrating GLO-PEM with remote sensing and GIS techniques in China during the period of 1989–2000. Using urban expansion and the mean NPP for the different land use types in the fourteen regions, the total loss of NPP was calculated as 0.95 Tg C, which accounted for 0.03% of the national NPP of 1989. The total loss of NPP due to the transformation from cropland to urban land accounted for 91.93%, followed by forest (7.17%) and grassland (0.69%). However, the conversion from unused land, industrial and construction land, and water bodies to urban land resulted in an increase in the NPP. The regions locating in eastern China and middle China had large reductions in the total NPP due to urban expansion.

A multi-model assessment of climate change impacts on the distribution and productivity of ecosystems in China

Potential twenty-first century changes in vegetation distribution and net primary production in China were assessed using three different vegetation models, including new process-oriented but observationally based models for net primary production and vegetation distribution. Climate change projections were derived from a set of seven global climate model outputs, pattern scaled to yield a 2 °C global warming by mid-century. The effects of the climate changes were assessed for the last three decades of the century, by which time global warming has reached 4 °C, with atmospheric carbon dioxide concentration ([CO2]) prescribed at 750 ppm. This scenario results in a limited northward expansion of tropical forests along China’s southern coast, and a larger northward shift of subtropical forest into the current temperate forest and crop areas. Alpine vegetation on the Tibetan Plateau is largely replaced by boreal and subalpine forest or shrubland. The largest uncertainties (differences between climate and/or vegetation models) occur in northeastern China. However, all models agree on shrinkage of boreal forests in the northeast and the effects of [CO2] in promoting woody vegetation at the expense of grasslands. The current cropping systems in North China extend further northward and westward. The productivity of forests in South China increases in all models, although the magnitude of the [CO2] effect remains uncertain.

Changes of net primary productivity in China during recent 11 years detected using an ecological model driven by MODIS data

Net primary productivity (NPP) is an important component of the terrestrial carbon cycle. Accurately mapping the spatial-temporal variations of NPP in China is crucial for global carbon cycling study. In this study the process-based Boreal Ecosystem Productivity Simulator (BEPS) was employed to study the changes of NPP in China’s ecosystems for the period from 2000 to 2010. The BEPS model was first validated using gross primary productivity (GPP) measured at typical flux sites and forest NPP measured at different regions. Then it was driven with leaf area index (LAI) inversed from the Moderate Resolution Imaging Spectroradiometer (MODIS) reflectance and land cover products and meteorological data interpolated from observations at 753 national basic meteorological stations to simulate NPP at daily time steps and a spatial resolution of 500 m from January 1, 2000 to December 31, 2010. Validations show that BEPS is able to capture the seasonal variations of tower-based GPP and the spatial variability of forest NPP in different regions of China. Estimated national total of annual NPP varied from 2.63 to 2.84Pg C·yr−1, averaging 2.74 Pg C·yr−1 during the study period. Simulated terrestrial NPP shows spatial patterns decreasing from the east to the west and from the south to the north, in association with land cover types and climate. South-west China makes the largest contribution to the national total of NPP while NPP in the North-west account for only 3.97% of the national total. During the recent 11 years, the temporal changes of NPP were heterogamous. NPP increased in 63.8% of China’s landmass, mainly in areas north of the Yangtze River and decreased in most areas of southern China, owing to the low temperature freezing in early 2008 and the severe drought in late 2009.

Assessing the impacts of droughts on net primary productivity in China

Frequency and severity of droughts were projected to increase in many regions. However, their effects of temporal dynamics on the terrestrial carbon cycle remain uncertain, and hence deserve further investigation. In this paper, the droughts that occurred in China during 2001–2010 were identified by using the standardized precipitation index (SPI). Standardized anomaly index (SAI), which has been widely employed in reflecting precipitation, was extended to evaluate the anomalies of net primary productivity (NPP). In addition, influences of the droughts on vegetation were explored by examining the temporal dynamics of SAI–NPP along with area-weighted drought intensity at different time scales (1, 3, 6, 9 and 12 months). Year-to-year variability of NPP with several factors, including droughts, NDVI, radiation and temperature, was analyzed as well.Consequently, the droughts in the years 2001, 2006 and 2009 were well reconstructed. This indicates that SPI could be applied to the monitoring of the droughts in China during the past decade (2001–2010) effectively. Moreover, strongest correlations between droughts and NPP anomalies were found during or after the drought intensities reached their peak values. In addition, some droughts substantially reduced the countrywide NPP, whereas the others did not. These phenomena can be explained by the regional diversities of drought intensity, drought duration, areal extents of the droughts, as well as the cumulative and lag responses of vegetation to the precipitation deficits. Besides the drought conditions, normalized difference vegetation index (NDVI), radiation and temperature also contribute to the interannual variability of NPP.

Spatiotemporal dynamics of forest net primary production in China over the past two decades

Forest ecosystems play an important role in global carbon cycle regulation. Clarifying the dynamics and mechanism of carbon sink is of both scientific and political importance. In this paper, we have investigated the spatiotemporal change of forest net primary production (NPP) in China for recent two decades based on the geographically weighted regression (GWR) with a cumulative remote sensing index, the maximum normalized difference vegetation index (NDVI max). GWR is a recently developed regression method with special emphasis on spatial non-stationarity. Outputs of forest NPP at three different stages was generated by the GWR model with NDVI max for the 1980s, early and late 1990s which were consequently analyzed. Our results indicated a wave-like pattern of change in forest NPP in the three stages with a trough-like depression for the early 1990s. The average forest NPP increased by about 0.72% from the 1980s to the late 1990s. A continuously increasing trend at a pace of 0.07% and 0.22% yr − 1 was observed in the tropical and subtropical zones from the 1980s to late 1990s respectively, while a continuously decreasing trend (− 0.05% yr − 1 ) was noted for the temperate zone. From forest type perspective, only the deciduous broadleaf forests exhibited a continuously decreasing trend of 0.18% yr − 1 . The complex spatiotemporal patterns revealed by this study suggest the need for further research in this direction in order to build in-depth insights into the revealed complexities.

Simulating crop net primary production in China from 2000 to 2050 by linking the Crop-C model with a FGOALS’s model climate change scenario

Net primary production (NPP) of crop represents the capacity of sequestrating atmospheric CO2 in agro-ecosystem, and it plays an important role in terrestrial carbon cycling. By linking the Crop-C model with climate change scenario projected by a coupled GCM FGOALS via geographical information system (GIS) techniques, crop NPP in China was simulated from 2000 to 2050. The national averaged surface air temperature from FGOALS is projected to increase by 1.0°C over this period and the corresponding atmospheric CO2 concentration is 535 ppm by 2050 under the IPCC A1B scenario. With a spatial resolution of 10 × 10 km2, model simulation indicated that an annual average increase of 0.6 Tg C yr−1 (Tg=1012 g) would be possible under the A1B scenario. The NPP in the late 2040s would increase by 5% (30 Tg C) within the 98 × 106 hm2 cropland area in contrast with that in the early 2000s. A further investigation suggested that changes in the NPP would not be evenly distributed in China. A higher increase would occur in a majority of regions located in eastern and northwestern China, while a slight reduction would appear in Hebei and Tianjin in northern China. The spatial characteristics of the crop NPP change are attributed primarily to the uneven distribution of temperature change.

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.

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.

Effect of Climate Change of Terrestrial Net Primary Productivity in China

Effect of Climate Change of Terrestrial Net Primary Productivity in China

Modelling the spatial pattern of net primary productivity in Chinese forests

The spatial patterns of biomass and net primary productivity in China’s forests were estimated using empirical data sets, remote sensing methods, and climate–vegetation models, and were analysed within a spatial analysis system. Differences between spatial modelling methods for estimating net primary production (NPP) were also examined and compared. The results indicate that the present spatial pattern of NPP in Chinese forest types is a result of both natural environmental factors and human land use patterns. Estimates of NPP for the tropical zone — seasonal rainforests and rainforests — were highest, ranging from 20 to 24 Mg ha −1 year −1. NPP was lowest in boreal zone forests comprised primarily of Scotch pine and Siberian pine, averaging only 6.7 Mg ha −1 year −1. The results reported here demonstrate the usefulness of spatial analyses techniques for improving the accuracy of NPP estimates and our understanding of NPP spatial patterns and dynamics in forest ecosystems.