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Home - Region - Concepts - Ecological processes in the landscape
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Neighbourhood effects. These effects, also known as "small landscape effects", occur when the abundance of a population is more influenced by adjacent habitats than by distant habitats. Neighbourhood effects always depend on the form of the landscape: Edge effects are an example of this process. One of the most documented examples of neighbourhood effects is nest parasitism by the brown-headed cowbird (Molothrus ater).
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These birds live in large flocks in open areas and do not make nests, but lay their eggs in the nests of other birds on the edges of the forest and leave them to be raised by the hosts. This has a large impact on birds that nest near the edges, as they generally lose their own brood in the process.
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Relationships of habitat donor and recipient (Source/ sink). Relatively productive habitats (with better soils, higher moisture and more suitable weather conditions) may act as donors (sources) of individuals that disperse to less productive habitats known as recipients (sinks). Populations in recipient habitats can not persist over time because reproduction is insufficient to counter rates of mortality and they require continuous migration from more productive nearby donor habitats.
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The composition (habitat types) and structure (distance between habitats) of the landscape influences the relationship between donor and recipient habitats. Few studies have described the relationship between these habitats, because it is so difficult to fully document reproduction and dispersion in various habitats for several years. However, it is easy to imagine situations where this dynamic is created by human intervention. For example, hunting near protected areas may establish a donor/recipient habitat.
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