Restoring habitat, in addition to conserving remnant habitat, is a priority for recovering degraded ecosystems. However, restoring habitat can be challenging, and management techniques often differ between restored habitat and remnant habitat in order to be effective.
Connectivity is important for both restored and remnant habitat, but for different processes. For newly restored habitat, biodiversity depends on colonization from a source population, which is promoted by connectivity.
Watts, K., and S. Hughes. 2024. Fragmentation impacts may be mixed for conservation but generally bad for restoration. Restoration Ecology: e14260.
In contrast, biodiversity in remnant habitat is primarily driven by the species that already occur there, which may be impacted by extinction if connectivity is not maintained. Although restoring new habitat and conserving remnant habitat are both important, most habitat fragmentation research only focuses on remnant habitat and the debate over the impacts of fragmentation per se.
Recent research uses simplified model landscapes to more thoroughly explore the role of connectivity in habitat restoration. Researchers used a 10×10 grid of cells to demonstrate different fragmentation scenarios for five species. In the conservation scenarios, intact habitat was reduced to a few patches. In the restoration scenarios, new habitat patches were created in a degraded landscape. For both conservation and restoration scenarios, model landscapes varied in the degree of fragmentation to illustrate colonization and extinction dynamics.
The study found that the number of species conserved in fragmented landscapes differed in conservation versus restoration scenarios. In conservation scenarios, fragmentation impacts on biodiversity varied depending on the time since fragmentation and dispersal ability of species. However, in restoration scenarios, fragmentation generally reduced biodiversity – if new habitat was isolated, then it couldn’t be colonized as effectively.
These model landscapes highlight the strong temporal aspect of fragmentation. In conservation scenarios, recently fragmented habitat maintained biodiversity, but over time, biodiversity decreased due to a time lag in extinction (known as “extinction debts”). In restoration scenarios, biodiversity may increase over time in restored habitat through colonization, but these “colonization credits” can only be realized with sufficient connectivity.
Given the high rate of habitat destruction globally, restoring habitat is necessary to aid conservation. Coordinating conservation and restoration efforts by restoring habitat close to protected remnant areas may promote dispersal to restored patches and benefit remnant habitat. Restoration efforts should aim to restore habitat that is not only high quality but also well-connected, through practices such as corridor construction or the creation of stepping stones.
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