Modeling net primary productivity of the terrestrial ecosystem in China from 1961 to 2005

Abstract

Net primary productivity (NPP) is the most important index that represents the structure and function of the ecosystem. NPP can be simulated by dynamic global vegetation models (DGVM), which are designed to represent vegetation dynamics relative to environmental change. This study simulated the NPP of China’s ecosystems based on the DGVM Integrated Biosphere Simulator (IBIS) with data on climate, soil, and topography. The applicability of IBIS in the NPP simulation of China’s terrestrial ecosystems was verified first. Comparison with other relevant studies indicates that the range and mean value of simulations are generally within the limits of observations; the overall pattern and total annual NPP are close to the simulations conducted with other models. The simulations are also close to the NPP estimations based on remote sensing. Validation proved that IBIS can be utilized in the large-scale simulation of NPP in China’s natural ecosystem. We then simulated NPP with climate change data from 1961 to 2005, when warming was particularly striking. The following are the results of the simulation. (1) Total NPP varied from 3.61 GtC/yr to 4.24 GtC/yr in the past 45 years and exhibited minimal significant linear increase or decrease. (2) Regional differences in the increase or decrease in NPP were large but exhibited an insignificant overall linear trend. NPP declined in most parts of eastern and central China, especially in the Loess Plateau. (3) Similar to the fluctuation law of annual NPP, seasonal NPP also displayed an insignificant increase or decrease; the trend line was within the general level. (4) The regional differences in seasonal NPP changes were large. NPP declined in spring, summer, and autumn in the Loess Plateau but increased in most parts of the Tibetan Plateau.