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Organism-environment feedback important for habitat restoration

Habitat destruction and fragmentation are primary causes of biodiversity loss. Yet many organisms affect their environments on various temporal and spatial scales. The modification and creation of the environment by organisms could potentially facilitate habitat restoration. For example, dune plants can reinforce and stabilize their habitat on drift sand; desert plants can accumulate soil particles and plant debris around them and facilitate their future recruitment. These organism-environment feedbacks can cause complex spatial patterns of species distributions to emerge and lead to surprising results in habitat restoration.

Following Levinsí patch occupancy model, C·I·B researchers and colleagues presented a differential-equation model, incorporating habitat restoration induced by organisms themselves (internal restoration) and by other organisms or/and abiotic causes (external restoration). Stability analysis revealed the existence of alternative equilibriums (i.e., bi-stability) in the system. This bi-stability (or threshold phenomenon) could arise from the density-dependent negative growth rates at low metapopulation size, indicating that a minimum amount of suitable habitat is required for metapopulation persistence. The internal restoration of habitat was identified as the trigger for the bi-stability, whereas the external restoration, in contrast, can eliminate the bi-stability from the system.

Haloxyon shrubs have been used for habitat restoration

Haloxyon shrubs have been used for habitat restoration in many desert areas of Central Asia as they accumulate soil particles and plant debris around the stems and form a fertile island for insects and plant seeds to survive in the harsh environment. This positive organism-habitat feedback has transformed many desert landscapes in the region. Photo Credit: Peter Bathory.




Read the papers:

Zhang, F., Tao, Y. & Hui, C. (2012) Organism-induced habitat restoration leads to bi-stability in metapopulations. Mathematical Biosciences, 240: 260-266.

For more information, contact Cang Hui at chui@sun.ac.za