Studying communities

Ecologists try to understand what is happening in the natural world at many different levels. As well as looking at individuals they study the relationships affecting populations (a group of the same species) or communities (a group of populations of different species living in the same area). Understanding how these complicated networks of species interact with each other and their environment is a fascinating area of ecology.

Looking at communities

What we might see as a bit of the countryside such as a woodland, or a stream, is to an ecologist a community of plants, animals and micro-organisms. A hedgerow, for example, may look simple, but a closer look reveals a community of between tens and thousands of species. As well as the species of shrub or tree that make up the hedge, there are plants that live at the base of the hedge that can include grasses, herbs, mosses and liverworts. The occasional tree may be planted within the hedgerow adding to the diversity of the habitat.

The hedgerow plants are a source of food for invertebrates, birds and small mammals as well as parasitic and pathogenic microorganisms. Some species eat different plants some specialize on a part of plant or a particular plant species. Pollinating insects and fruit eating birds are important in the life cycles of many of these hedgerow plants. The plants also provide structure: a nest site for birds, a refuge for overwintering insects or a framework on which to construct a spider’s web. The plant-eating animals are food for predatory species, who may be in turn food for another species. The remains of all are food sources for scavengers and detritivores (species that eat dead matter) such as earthworms and fungi. Some species will spend all their lives in the hedgerow whilst others will live there for only part of their life or pass through as visitors. It is hard to imagine something so complex, but it can be visualised as a web with each organism as a join in the web and the strands representing the relationships between them. Because species are connected by this network of interactions, a change in one species can have both direct and indirect effects on other species in a community.

Why study communities?

Understanding what happens at a community level can help answer questions about the natural world and to solve environmental problems. Community ecology is important in many areas from understanding the effects of introduced species, to making farming more sustainable, conserving species or predicting the possible effects of climate change.

Next: Applying ecology

Comments