森林破碎化对鼠类—种子互作网络的影响

Impact of forest fragmentation on rodent- seed network

森林碎片化严重威胁生态系统的健康,导致物种多样性、生态系统稳定性的降低。鼠类和森林种子是一类重要的互作网络,在生物多样性维持和生态系统服务功能上发挥着重要作用,有关森林斑块大小及演替阶段对鼠类—种子互作网络的影响的报道较少。本研究以都江堰地区亚热带森林鼠类—种子互作系统为例,选取15个不同大小和演替阶段的森林斑块,结合红外相机监测和种子标记,通过监测鼠类与种子的互作过程,分析了斑块大小和演替阶段对鼠类—种子互作关系的影响,并绘制了各斑块鼠类—种子互作网络图谱,发现:中斑块(2-4 hm^2)森林中鼠类的物种数最多,大斑块(9-30 hm^2)最少;演替后期(20-40 yrs)次生林的加权嵌套度(Weighted-Interaction Nestedness Estimator,WINE)显著地高于演替早期(10-20 yrs)次生林;原始林网络内相关植物的植株总数和胸径(DBH)总和都要显著大于次生林。我们的结果说明森林破碎化对鼠类—种子互作网络的加权嵌套度有一定影响,对其他网络参数影响不大,可能与其种间关系泛化度较大有关。该结果对进一步研究种间互作关系及生态网络结构与功能具有一定的参考意义。

Forest fragmentation is threatening the health and survival of ecosystems though reducing species diversity and sustainability of the ecosystems. As an important plant-animal network,plant-rodent interaction plays a significant role in maintaining biodiversity and function of a forest,but their functional response to habitat patch size and succession stage is seldom investigated. Here,we monitored seed predation by small rodents in 15 forest patches with different sizes and at different stages of succession in a subtropical forest in Dujiangyan,Sichuan Province. Based on a new method integrating IR camera monitoring with a seed tagging method,we measured species interaction strengths between seeds and rodents,and then illustrated the rodent-seed interaction network of different patches,so as to analyze the influence of size of the forest patch and succession stage on parameters of the networks. We found that rodent species richness was highest in medium patches（ 2- 4 ha.）,and lowest in large patches（ 9- 30 ha.）; Weighted-Interaction Nestedness Estimator（ WINE） in secondary forests was significantly higher in the patches of late succession stage（ 20- 40 yrs） than that of early succession stage（ 10- 20 yrs）; the total number and sum of diameter at breast height（ DBH） of plants in the seed-rodent network was significantly higher in the primary forests than the secondary ones. Our results suggest that forest fragmentation showed some influences on WINE of seed-rodent network,but not on the other network parameters,which is probably due to the interaction generality of the seed-rodent network. This study provides a basis for further research on species interactions between trees and rodents,and the structure and function of the seed-rodent network.