Jonathan Nathaniel Hayes
A Critical review of Anthropogenic Halo Disturbances Alter Landscape and Plant Richness: A Ripple Effect
In this interesting study, researchers investigated the hypothesis that recreational areas have a “halo disturbance effect” deeper into the forest area than just the edge habitat. Far from being the next installment of a popular XBox video game, halo disturbance is the negative ripple effect that anthropogenic activity has further into the “patch” of woods than simply where the human activity is taking place.
This is not only due to the clearing of forest for fields and lawns but also by the activities and noise created by immediate human disturbance.
When public green spaces or “recreational landscapes” are created it fragments the landscape into clusters of species called patches. These patches have edge habitat (the area adjoining the cleared public use space). Typically, In a larger environment, edge habitat, between forest and field, development and wilderness, represents one of the most active and diverse portions of land for plant and animal species. Typically, plants flourish in the direct light, bringing to them birds and rodents which in turn bring the predators. I therefore found it quite interesting that, on a smaller scale, these recreational landscapes see a reduction in species diversity, particularly of those flora species dependent on animal seed dispersal for reproduction. This is due to the frequency of human activity and noise and the negative effect it has on the animals- including sound sensitive birds- that are responsible for consuming their fruits and distributing their seeds through their fecal excretions. Because these recreational landscapes produce patches of land, rather than true edge- field to forest- habitat, the diversity of the entire patch can be adversely effected by halo disturbance.
While it is true that wind-dispersed plants tend to do 6% better in such recreational landscapes, there is an overall degradation of habitat since there is a 13% reduction in animal-distributed flora, creating a loss of species diversity. While it seems the structural connectivity of wind dispersal is improved slightly, the more complicated functional connectivity is reduced overall by anthropogenic disturbance.
In the discussion portion of the article, the authors offered some thought provoking ideas for addressing the adverse ecological effects of halo disturbance. They were good ideas, with the exception of #2. IN this recommendation, the authors suggested “fencing recreational patches to prevent HDEs…” While fencing in these patches of undisturbed habitat may make some sense from a botanical perspective, it would ultimately serve to further fragment the landscape by creating barriers to travel for medium and larger sized fauna, some of which are responsible for the seed dispersal of flora most effected by halo disturbance.