鸟类捕食隐藏觅食的蛀茎虫对芦苇的影响

Birds are important ecosystem service providers and have influence on many ecological processes. It has been demonstrated in forest and agroforestry systems that bird predation can have positive indirect effects on trees and shrubs. But the impacts of bird predation on grasses have been unambiguous. The reed parrotbill (Paradoxornis heudei) is a reed habitat specialist, and stem-boring caterpillars (Archanara spp.) within the stem of common reed (Phragmites australis) are one of their dominant food resources. In order to retrieve stem-boring caterpillars, reed parrotbills have to break the stem, thus show a potential negative direct impact on reeds. While reed parrotbills' predation on stem-boring caterpillars will reduce the occurrence and abundance of stem-boring caterpillars, thus have the potential to show a positive indirect effect on reeds. In this project, we are proposing to use exclosure to measure the impacts of bird predation on stem-boring caterpillars and shoot mortality of the common reed, and investigate the relationships between reed parrotbills, stem-boring caterpillars and common reeds. This could help us to figure the role of reed parrotbill in this ecological process of reed-dominated ecosystem and discuss the ecosystem service provided by reed parrotbill.

鸟类是重要的生态系统服务提供者，在多个生态系统过程中有重要调控作用。鸟类捕食在以木本植物为初级生产者的生态系统中对植物有显著正间接影响，而鸟类捕食对草本植物的影响不甚明确。震旦鸦雀是芦苇生境特化种，芦苇蛀茎虫是其主要食物之一。其捕食蛀茎虫需要啄开芦苇地上茎，有可能导致芦苇地上茎死亡，而对芦苇产生负的直接影响；而其捕食蛀茎虫、减少蛀茎虫的发生率和丰度，又有可能对芦苇产生正的间接作用。本项目以震旦鸦雀-蛀茎虫-芦苇为研究系统，通过野外原位控制实验，观测和样方采样比较鸟类捕食存在和不存在情况下蛀茎虫和芦苇的响应，研究震旦鸦雀等食虫鸟类捕食蛀茎虫对芦苇的影响，刻画震旦鸦雀等食虫鸟类、蛀茎虫和芦苇之间的关系，揭示芦苇生境特化鸟类-震旦鸦雀等食虫鸟类在其赖以生存的芦苇生境生态系统过程中的作用和地位，探讨震旦鸦雀等食虫鸟类在以芦苇占优势的生态系统中的生态系统服务功能。

鸟类是重要的生态系统服务提供者，在多个生态系统过程中有重要调控作用。鸟类捕食在以木本植物为初级生产者的生态系统中对植物有显著正间接影响，而鸟类捕食对草本植物的影响不甚明确。震旦鸦雀是芦苇生境特化种，芦苇蛀茎虫是其主要食物之一。其捕食蛀茎虫需要啄开芦苇地上茎，有可能导致芦苇地上茎死亡，而对芦苇产生负的直接影响；而其捕食蛀茎虫、减少蛀茎虫的发生率和丰度，又有可能对芦苇产生正的间接作用。本项目以震旦鸦雀-蛀茎虫-芦苇为研究系统，通过野外原位控制实验，观测和样方采样比较鸟类捕食存在和不存在情况下蛀茎虫和芦苇的响应，研究发现震旦鸦雀捕食能减少75%的蛀茎虫发生率和90%的蛀茎虫丰度，同时震旦鸦雀捕食蛀茎虫会使蛀茎虫发生芦苇枝的死亡率从3%左右增加到9%，由于其芦苇植被生产力较高，芦苇枝死亡率的增加能否在产生群落层面的影响还未可知，本项目研究结果初步表明震旦鸦雀的捕食作用具有相对复杂的生态效应，而不同于以往简单的认为食虫鸟类对植物都是有利的。