CO2浓度升高和氮沉降增加对杨桦幼林叶片虫食水平和节肢动物密度的影响机制

In the context of global environmental changes, elevated atmospheric CO2 and increased nitrogen deposition may occur simultaneously in many countries and regions (including China), therefore, examining the individual and interactive effects of the two environmental factors on arthropod densities and canopy herbivory in natural forests has both ecological and economic significance. In this proposed research project, open-top chambers will be used to provide a high CO2 concentration environment, and ammonium nitrate solution will be sprayed into the soil to simulate nitrogen deposition. Based on the environmental manipulation experiment conducted in a young poplar-birch forest in Changbai Region, we will examine the impacts of the doubled amount of nitrogen deposition and the increased CO2 concentration to 550 ppm on growth and leaf quality of temperate forest tree species (Betula platyphylla), and we will reveal the responses mode and intensity of arthropod densities (including the responses of herbivores, insectivores and detritivores) and canopy leaf herbivory under this experimental conditions. By performing regression analysis on the data of leaf quality (including C:N:P stoichiometric ratios) and canopy herbivory, we will assess the influence levels of each leaf indices on leaf herbivory intensity. The study would provide a new perspective and experimental evidence on understanding the ecological mechanisms underlying the changes in community structure and herbivory of forest arthropods in an era of rapid global environmental change.

全球环境变化背景下，包括我国在内的许多国家和地区，大气CO2浓度升高和氮沉降增加很可能同时发生，研究这两个环境因素单独和交互作用下，天然林内节肢动物密度和冠层叶片虫食水平的响应，具有重要的生态意义。本项目使用开顶式气室模拟大气CO2浓度升高，使用喷洒硝酸铵溶液的方法模拟氮沉降；通过在长白山天然杨桦林幼林内进行的环境操控实验，检验氮沉降量倍增和大气CO2浓度升高至550 ppm时，温带森林树木（白桦）的生长、叶片品质和叶片C:N:P等化学计量特征的响应，明确节肢动物（植食类、食虫类、食碎屑类）个体数量以及冠层叶片虫食水平对CO2浓度升高和氮添加的响应方式和强度；分析叶片品质（包括C:N:P等化学计量比值）与叶片虫食水平之间的关联，确定对冠层叶片虫食水平有显著影响的叶片特征指标。这项研究将为揭示全球变化下森林节肢动物群落结构及其取食的变化机理，提供新的思路和实验证据。