托福阅读例题分析及答案

以下是托福阅读例题分析及答案示例：

The answer to the question "What types of long-term stability do ecosystems achieve?" may be found in the passage's consideration of the assembly rules that underlie the structure of plant communities. Plant communities are able to achieve long-term stability assemblages through a combination of structuring factors that create both environmental filtering and species sorting. Environmental filtering results from the spatial heterogeneity found within plant communities, which creates micro-environments that select for certain traits. For example, some shaded areas may be more moist, while others may be drier. Species sorting results from the plant species' abilities to disperse and occupy different niches within the plant community. This process results in species becoming spatially separated, which reduces competition and increases stability.

The assembly rules that underlie the structure of plant communities are key to understanding long-term stability in ecosystems. The assembly rules dictate which species can occupy certain niches, and in turn influence the species richness and diversity of the plant community. A plant community's species richness and diversity directly impact its ability to withstand environmental change. Plant communities with high species richness and diversity are more likely to have keystone species, which are essential to the health and function of the ecosystem. Keystone species play a particularly important role in maintaining ecosystem stability.

A plant community's long-term stability also depends on its resiliency, or its ability to bounce back from environmental change or disturbance. Resilient plant communities are more likely to withstand perturbations, such as herbivore outbreaks or severe weather events, and are better able to recover once the disturbance has passed. Key factors influencing plant community resiliency include species richness and diversity, community evenness, and functional group diversity. Plant communities with high species richness and diversity are more likely to have keystone species, which are essential to the health and function of the ecosystem.

The answer to the question "What are some factors that influence plant community assembly?" may be found in the passage's discussion of extrfloral nectaries. Extrfloral nectaries are structures located at the base of each sepal that attract several different species of ants. These ants provide protection to the plant by defending it from herbivores and competing plant species. In return for this protection, the plant provides the ants with nectar, which the ants collect and store in their underground chambers. These chambers serve as a source of water and food for the ants, as well as a refuge in case of emergency.

The extrfloral nectary example is used to demonstrate how plants can attract specific pollinators or herbivore controllers to increase the health and function of the ecosystem. This is turn助于 increase plant community assembly and long-term stability.

答案示例：

• 生态系统可以达到哪些类型的长期稳定性？答：生态系统可以达到的环境过滤和物种分类的长期稳定性。环境过滤产生于植物群落内的空间异质性，创造了选择某些特征的微环境。例如，一些阴影区域可能更加潮湿，而其他区域可能更加干燥。物种分类是由植物物种传播和占据植物群落中的不同生态位的能力产生的。这种过程导致物种空间分离，减少竞争，增加了稳定性。
• 植物社区的稳定性还取决于什么？答：植物社区的稳定性还取决于其弹性，即从环境变化或干扰中恢复过来的能力。具有弹性的植物社区更能承受扰动，如食草动物爆发或严重天气事件，并在干扰过去后更好地恢复。影响植物社区弹性的关键因素包括物种丰富度和多样性、群落均匀度以及功能组多样性。
• 植物社区的组成受到哪些因素的影响？答：植物社区的组成受到植物物种吸引不同种类蚂蚁的外部花蜜来源的影响。这些蚂蚁保护植物免受食草动物和竞争植物的侵害。作为回报，蚂蚁从花蜜来源中收集并储存在它们的地下巢穴中的花蜜和水。这些巢穴成为蚂蚁在紧急情况下的食物和水源的来源，也是它们在巢穴中繁殖的避难所。这个例子是用来展示植物如何吸引特定的传粉者或控制食草动物者来提高生态系统的健康和功能。这有助于增加植物社区的组成和长期稳定性。