Effects of abiotic, top-down and bottom-up factors for the vertebrate community composition of a spiny forest ecosystem in Madagascar

非生物、自上而下和自下而上因素对马达加斯加多刺森林生态系统脊椎动物群落组成的影响

• 批准号: 27480704
• 负责人: Professor Dr. Jörg U. Ganzhorn
• 金额: --
• 依托单位: Département de Biologie Animale
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/27480704?language=en
• 关键词: Effects; abiotic; top; down; bottom

The importance of top-down and bottom-up processes for the abundance of species in vertebrate communities of terrestrial forest ecosystems remains a matter of debate. In top-down processes predators should limit herbivores, thus reducing herbivore pressure on the vegetation. This results in increased forest regeneration. If bottom-up processes were more effective, the availability and quality of plants (primary production) would limit herbivore populations which in turn limit their predators. In the presence of a predator, ecosystems dominated by top-down effects should combine low population densities of herbivores with high plant production. In contrast, in ecosystems dominated by bottom-up effects herbivore densities should be correlated positively with primary production. Analyses of these predictions in vertebrate communities are hampered by the difficulties of manipulating large carnivores experimentally and by complex food web connections rather than linear relationships between trophic levels. The goal of the project is to identify the effects of abiotic, top-down and bottom-up factors on species abundances in vertebrate communities of Madagascar¿ spiny forest and their impact on forest regeneration. The spiny forest ecosystem of Madagascar contains all trophic levels but each level consists of very few species, making analyses feasible. We will focus on the impact of a top predator, Galidictis grandidieri, (= top-down effects) and primary production (= bottom-up effects) on populations of consumers of plant material, using a two factorial study design (predation / high primary production; no predation / high primary production; predation / low primary production; no predation / low primary production. The response variables will be: 1. characteristics of consumer populations (density, structure, dynamics) and 2. forest regeneration (abundance and species composition of seedlings). This approach should allow to assess the impact of the predator on prey populations and, across the trophic cascade, on the primary production and forest regeneration.

自上而下和自下而上的过程对于陆地森林生态系统脊椎动物群落中物种的抽象的重要性仍然是一个辩论问题。在自上而下的过程中，捕食者应限制食草动物，从而减少对植被的草食动物压力。这导致森林再生增加。如果自下而上的过程更有效，则植物的可用性和质量（主要生产）将限制草食动物种群，从而限制其捕食者。在存在捕食者的情况下，以自上而下的影响为主的生态系统应将草食动物的人口密度与植物的产量高。相反，在以自下而上效应为主的生态系统中，食草动物的密度应与一级生产呈正相关。通过实验和复杂的食物网络连接而不是营养水平之间的线性关系，对脊椎动物群落中这些预测的分析受到了阻碍。该项目的目的是确定马达加斯加脊椎动物群落中的非生物，自上而下和自下而上的因素对棘突森林的物种丰度的影响及其对森林再生的影响。马达加斯加的多刺森林生态系统包含所有营养水平，但每个水平都由很少的物种组成，因此可行分析。我们将专注于顶级捕食者，Galidictis Grandidieri，（=自上而下的效果）和初级生产（=自下而上的影响）对植物材料消费者人群的使用，使用两种阶乘研究设计（捕食 /高初级生产；无捕食 /高级生产；捕食 /高生产；掠食 /低初级产量 /低初级生产；不捕食 /低初级生产；响应变量均可消费。 （幼苗的丰度和物种组成）。