模拟夏季干旱对东灵山森林植被动态的影响

Simulating impacts of summer drought on forest dynamics in Dongling Mountain

应用LPJ-GUESS植被动态模型,在耦合不同物种的干旱响应策略的基础上,研究了夏季干旱化对东灵山地区森林植被的物种组成及其功能的影响。结果表明,在气候变暖、降水减少、CO2浓度升高的情况下,无论树种采取何种策略,东灵山暖温带森林的总净初级生产力和生物量都有增加的趋势,降水在未来近一个世纪内尚未成为本地区植被生长的限制因子。但森林植被的树种组成与树种的干旱响应策略密切相关,不耐旱的物种核桃楸(Juglans mandshurica)的生物量水平在长期干旱条件下并没有降低,而耐旱的物种辽东栎(Quercus liaotungensis)在受到干旱化长期影响时,其生物量有下降的趋势。这种响应策略也会导致植被蒸散等生态系统水分循环过程的差异。因此,降水变化对森林生态系统影响的长期模拟研究应该考虑物种对干旱的不同响应策略。

Aims Climatic change has and will continue to decrease summer precipitation in the Dongling Mountain area of Beijing, China. Decreased precipitation impacts trees and hence temperate forest vegetation. Experimental studies suggested that the effects of decreasing summer precipitation on forest were closely related to species-specific characteristics during drought. Our major goals were to project the impact of decreasing summer precipitation on forest dynamics in this region and to analyze long-term consequences of tree-species specific drought response of the temperate forest ecosystem. Methods We used LPJ-GUESS dynamic vegetation model coupled with different water uptake strategies to investigate drought effects on trees and forests in this temperate region of China. Important findings Increases in net primary productivity （NPP） and carbon biomass of the predicted area under future climate conditions of increased temperature and elevated CO2 concentration were independent of summer precipitation. This suggests that precipitation will not be the limiting factor in this area. However, tree diversity strongly depended on the drought response that we assumed. Drought-sensitive tree species （e.g., Juglans mand- shurica） were not influenced by long-term drought, whereas the carbon biomass of the most drought-tolerant spe- cies （i.e., Quercus liaotungensis） would decrease in the future. Moreover, tree-species specific drought response will affect the water cycle of the temperate forest, including evapotranspiration. Our findings of the spe- cies-specific drought response should be considered in future ecosystem models.