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Forecasting carbon budget under climate change and CO2 fertilization for subtropical region in China using Integrated Biosphere Simulator (IBIS) model

Zhu Q., Jiang H., Liu J., Peng C., Fang X., Yu S., Zhou G., Wei X., Ju W.

Polish Journal of Ecology

2011

Vol. 59, nr 1

3-23

The regional carbon budget of the climatic transition zone may be very sensitive to climate change and increasing atmospheric CO2 concentrations. This study simulated the carbon cycles under these changes using process-based ecosystem models. The Integrated Biosphere Simulator (IBIS), a Dynamic Global Vegetation Model (DGVM), was used to evaluate the impacts of climate change and CO2 fertilization on net primary production (NPP), net ecosystem production (NEP), and the vegetation structure of terrestrial ecosystems in Zhejiang province (area 101,800 km2, mainly covered by subtropical evergreen forest and warm-temperate evergreen broadleaf forest) which is located in the subtropical climate area of China. Two general circulation models (HADCM3 and CGCM3) representing four IPCC climate change scenarios (HC3AA, HC3GG, CGCM-sresa2, and CGCM-sresb1) were used as climate inputs for IBIS. Results show that simulated historical biomass and NPP are consistent with field and other modelled data, which makes the analysis of future carbon budget reliable. The results indicate that NPP over the entire Zhejiang province was about 55 Mt C yr[^-1] during the last half of the 21st century. An NPP increase of about 24 Mt C by the end of the 21st century was estimated with the combined effects of increasing CO2 and climate change. A slight NPP increase of about 5 Mt C was estimated under the climate change alone scenario. Forests in Zhejiang are currently acting as a carbon sink with an average NEP of about 2.5 Mt C yr[^-1]. NEP will increase to about 5 Mt C yr[^-1] by the end of the 21st century with the increasing atmospheric CO2concentration and climate change. However, climate change alone will reduce the forest carbon sequestration of Zhejiang.s forests. Future climate warming will substantially change the vegetation cover types; warm-temperate evergreen broadleaf forest will be gradually substituted by subtropical evergreen forest. An increasing CO2 concentration willhave little contribution to vegetation changes. Simulated NPP shows geographic patterns consistent with temperature to a certain extent, and precipitation is not the limiting factor for forest NPP in the subtropical climate conditions. There is no close relationship between the spatial pattern of NEP and climate condition.

Effects of Pinus massonian plantations on soil macroarthropods in degraded ultisol, Subtropical China

Ding C., Hu F., Zhou J., Cao Z., Li H., Dai Z.

Archives of Environmental Protection

2008

Vol. 34, no. 3

17-20

In the degraded red soil of subtropical China, restoration activities during the last century have mainly relied on extensive plantations of Pinus massonian. We analyze the changes in the soil macroarthropods in P. massonian plantations and the possible relationships between these changes and soil chemical parameters. The study revealed significant differences in the abundance of soil macroarthropods between the P. massonian plantations and the natural regenerated mesophilous herbosa (Nl). The sharply differentiated pattern of soil macroarthropods seems closely linked to soil chemistry. Significant correlations of the abundance of soil macroarthropods with soil parameters suggest that their populations could have been affected by P massonian. The total abundance, the abundance of Hymenoptera and Termite were less in the P. massonian plantations when compared to the natural regenerated mesophilous herbosa (Nl). This survey showed that P.massonian could adversely affect the decomposer community which could lower the nutrient cycling rate, thus P.massonian may not be an ideal plantation for restoration of eroded Ultisol, Subtropical China.