September 9, 2012
‘Human Activities’ Reduce Desert Environment Diversity
Brett Smith for redOrbit.com — Your Universe Online
Human activities and disturbances can put a significant amount of stress on local environments and a new research review has shown that the functional diversity in arid, desert environments can be affected by the hand of man.
According the report published in the Journal of Arid Environments, mammalian communities living in dry ecosystems are "drastically changing" as a result of human activities.
"We report for the first time that in drylands, the effect of human-induced disturbances on mammal functional diversity is negative," said study co-author Veronica Chillo, a biologist in the Functional diversity Research Group at the Argentinian Institute of Arid Lands Research.
"Regardless [of] the characteristic of the disturbance, functional diversity is diminished,” she told BBC News.
The review culled information from 25 studies and included 110 mammalian species were that evaluated for the effects of human-caused disturbances like poaching, logging, grazing, fires, and introduction of invasive species.
Although deserts and arid lands appear to be desolate places and therefore more resilient to manmade disturbances, they often support an intricate and sensitive ecosystem for smaller mammal that live in concert with plant and other animal species. Herbivores play important role by dispersing plant seeds and other mammals enrich the soil by digging tunnels that increase water infiltration, according to the review.
Because living in these ecosystems can be a delicate balance for many mammals, any drastic changes to the local ecosystem can result in a negative impact on their diversity. The researchers found several examples of population decreases and even localized extinctions as a result of human disturbances.
The review also noted that low and unpredictable rainfall could exacerbate damage caused to plant life and the larger ecological cycle.
According to the review, the human impacts that are most damaging to mammals are those that fundamentally remade parts of the local habitat, such as fires or overgrazing that wiped out any desert grasses.
"The most negative effect is seen when disturbances change the conditions of the system [such as something that] modifies the structure or dominant plant species," Chillo said.
Interestingly, the team found that fires that occurred at least a year ago seemed to have a more detrimental effect than newer fires because the wiping out of vegetation by a fire does not impact the ecosystem as much as the subsequent replacement of vegetation that occurs after the fire has run its course.
One encouraging find was that moderate grazing had a small, yet measurable impact on mammal diversity. The researchers noted that this “should open new avenues of research and discussions regarding alternative management strategies of sustainable livestock production.”
Ultimately, the report said that the human disturbances of dry and arid lands is highly complex and the result of a confluence of factors, but understanding and maintaining the functional diversity in these lands should be a top priority since diversity begets a more stable ecosystem.
The report added that conservation of these ecosystems is a self-serving goal for society since they provide all sorts of benefits, from storing carbon to producing food.