杂食性对食物链长度的塑造作用研究

The length of the food chain is determined not only by trophic pattern of the top predators, but also by the omnivory of middle-trophic and primary consumers. This study focuses on the study of omnivory by using omnivorous consumers from lake ecosystems as models. We ask 1) between ecosystems, how omnivory of consumers responds to the gradient of resource availability and further affects the food chain length; 2) within an ecosystem, how habitat heterogeneity (or habitat coupling intensity) affects the omnivory of consumers and further the length of food chains; and 3) within an ecosystem, how can seasonal changes in resource availability affect the omnivory of consumers and then affect the length of food chains? This study is of great theoretical and emperical significance for the accurate evaluation of food chain length and its potential influencing factors.

食物链长度不仅由顶级捕食者的营养特征决定，同时也会受到中营养级消费者以及初级消费者的杂食性影响。本研究以杂食性为研究切入点，选择湖泊中消费者群落为研究对象，拟通过野外比较湖沼学调查和野外定点季节观测，探究1）在生态系统间，消费者群落的杂食性特征如何响应资源可利用性的梯度并影响食物链长度；2）在生态系统内，生境异质性水平（或生境偶联强度）如何影响消费者群落的杂食性特征并影响食物链长度；3）在生态系统内，资源可利用性的季节变化如何影响消费者群落的杂食性特征，进而影响食物链长度？本研究对准确评估食物链长度及其潜在影响因素具有重要理论意义。

食物链长度不仅由顶级捕食者的营养特征决定，同时也会受到中营养级消费者以及初级消费者的杂食性影响。本研究以杂食性为研究切入点，以鱼类和长江通江和非通江湖泊为研究区域，对季节性水位波动下的鱼类群落结构和水生食物网结构、营养级、鱼类营养生态位等方面进行了研究，结果表明：不同水位时期，食物网有机质来源发生明显变化，消费者在涨水期以沉水植物为主，而在枯水期以凋落物和颗粒有机物为主；食物网结构和营养级出现明显的季节变化，枯水期消费者营养级普遍升高；鱼类群落在丰水期与枯水期的核心生态位发生偏移，群落结构发生变化。