中国成熟林植被和土壤固碳速率对气候变化的响应

Response of vegetation and soil carbon accumulation rate for China's mature forest on climate change

基于B2气候变化情景数据,利用大气-植被相互作用模式AVIM2,模拟预测了1981–2040年中国成熟林植被和土壤固碳速率的时空变化特征及其对气候变化的响应。结果表明,中国森林区域平均气温从1981年的7.8℃增加到2040年的9.0℃,森林区域降水量略有增加。成熟林植被碳总量从8.56 Pg C增加到9.7 Pg C,植被固碳速率在–0.054–0.076 Pg C·a–1之间波动,平均值为0.022 Pg C·a^(–1)。成熟林土壤碳总量从30.2 Pg C增加到30.72 Pg C,土壤固碳速率在–0.035–0.072 Pg C·a^(–1)之间波动,平均值为0.010 Pg C·a–1。虽然研究时段内中国植被和土壤固碳总量均没有显著变化趋势,但区域植被和土壤固碳速率对气候变化的响应具有显著空间差异。未来在气温增幅较大的东北和东南林区,特别是在东北的长白山林区,森林植被和土壤固碳速率将大大降低;而在气温增幅不大的西南林区南部和其他林区,植被和土壤固碳速率将提高。统计结果表明未来气候变暖不利于成熟林固碳。

Aims This study aims to evaluate the impacts of future climate change on vegetation and soil carbon accumulation rate in China＇s forests.Methods The vegetation and soil carbon storage were predicted by the atmosphere-vegetation interaction model（AVIM2） based on B2 climate change scenario during the period of 1981–2040. This study focused on mature forests in China and the forested area maintained constant over the study period. The carbon accumulation rate in year t is defined as the carbon storage of year t minus that of year t-^–1. Important findings Under B2 climate change scenario, mean air temperature in China＇s forested area was projected to rise from 7.8 ℃ in 1981 to 9.0 ℃ in 2040. The total vegetation carbon storage was then estimated to increase from 8.56 Pg C in 1981 to 9.79 Pg C in 2040, meanwhile total vegetation carbon accumulation rate was estimated to fluctuate between –0.054–0.076 Pg C·a^-1, with the average of 0.022 Pg C·a^-1. The total soil carbon storage was estimated to increase from 30.2 Pg C in 1981 to 30.72 Pg C in 2040, and total soil carbon accumulation rate was estimated to vary in the range of –0.035–0.072 Pg C·a^-1, with the mean of 0.010 Pg C·a^-1. The response of vegetation and soil carbon accumulation rate to climate change had significant spatial difference in China although the two time series did not show significant trend over the study period. Our results also showed warming was not in favor of forest carbon accumulation, so in the northeastern and southeastern forested area, especially in the Changbai Mountain, with highest temperature increase in the future, the vegetation and soil carbon accumulation rate were estimated to decrease greatly. However, in the southern of southwestern forested area and other forested area, with relatively less temperature increase, the vegetation and soil carbon accumulation rate was estimated to increase in the future.