Wildlife in Trouble from Oil Palm Plantations, Researchers Say

ScienceDaily — Forest fragmentation driven by demand for palm oil is having a catastrophic effect on multiple levels of biodiversity, scientists from Queen Mary, University of London have discovered.

The researchers are worried that unless steps are taken to safeguard and manage the remaining forest, then certain species will struggle to survive.

The study, which focused on bats as an indicator of environmental change, was published in the journal Ecology Letters.

The team conducted bat surveys in pristine forest and also in forest patches of varying size in central Peninsular Malaysia. They recorded the numbers of different species present and also assessed the level of genetic diversity within populations of some species.

Lead author Matthew Struebig, jointly based at Queen Mary University of London and the University of Kent, said: "We found that smaller forest areas support fewer species, and that those species that remain face an eventual decline, potentially leading to local extinction in the long-term."

When the team compared the number of species present to genetic diversity within populations they found that fragmentation appeared to have an even greater impact on genetic loss, which might also be important for long-term population viability.

"We found that in order to retain the numbers of bat species seen in pristine forest, forest patches had to be larger than 650 hectares, however to retain comparable levels of genetic diversity, areas needed to be greater than 10,000 hectares," he said.

Co-author Stephen Rossiter, also at Queen Mary, emphasised that the findings could have important implications for forest management in the face of the ever-growing demand for oil palm plantations.

He said: "We found that while more species existed in larger forest patches, even small fragments contributed to overall diversity. Therefore, conservation managers should aim to protect existing small fragments, while seeking to join up small forest areas to maximise diversity."

Source: Sciencedaily.com

There's No Magic Number for Saving Endangered Species

ScienceDaily (May 17, 2011) — A new study offers hope for species such as the Siberian Tiger that might be considered 'too rare to save', so long as conservation efforts can target key threats.

The findings have important implications for conserving some of the world's most charismatic endangered species, which often exist in populations far smaller than the many thousands of individuals that earlier studies had argued were necessary for viability.

Charismatic examples include the mountain gorilla, which likely now number 1,000 or less, the approximately 450 remaining Amur or Siberian tigers, the 180-500 remaining mature Philippine eagles, and the 70 wild Puerto Rican parrots.

The findings of a UK-US research team, the largest critical review of the use of minimum viable population (MVP) (*1) numbers in conservation, dispute the use of a universal MVP as a yardstick for conservation policies. According to the researchers there is no single population size that can be used as a catch-all guideline to save endangered species.

Co-author of the report, Dr. Philip Stephens, School of Biological and Biomedical Sciences, Durham University, said: "Populations usually show rapid declines as a result of human activities such as hunting and habitat conversion. The results of the study are encouraging and show that if we can remove the negative effects of human activities, even relatively small populations could be viable in the long term."

Dr. Greg Hayward, the U.S. Forest Service's (USFS) regional ecologist for Alaska said: "This is good news for biologists working to save species like the tiger. There's a lot of work to do to arrest the effects of poaching, prey loss and habitat destruction. However, if that work is successful, the tiger might yet be able to recover, despite the relatively small size of most tiger populations."

The study, published in the journal, Trends in Ecology and Evolution, shows that population sizes required for long-term viability vary, both within and among species, and depend on the specific circumstances in which the population is found. Estimates of viable population sizes were typically reduced to hundreds rather than thousands of individuals for populations that were relatively stable.

Previous studies have suggested that the allocation of conservation effort should be related to the number of individuals in threatened populations. For species which would require intense effort to raise numbers to 5,000 individuals, it might be too late to act and better to concentrate limited conservation resources elsewhere, the previous studies have suggested.

Researchers on the US-UK team argue that conservationists should not give up on saving an endangered species if its population is below an MVP figure, and they advise policy-makers to be cautious about setting guidelines for 'safe' population sizes.

The researchers also warn against potential complacency and stress the need to look in detail at the specific threats that a species faces. They argue that no population size is likely to be safe from extinction when conservation activities fail to reduce the impact of the factors causing the population to decline.

Dr. Curt Flather, a research ecologist with the USFS Rocky Mountain Research Station in Colorado said: "The enormous variability in estimates shows that many populations also need to be highly abundant to be viable. The extinction of the passenger pigeon, which numbered 3 to 5 billion individuals in North America during the 1800s, is a reminder that population size alone is no guarantee against extinction."

Read more at http://www.sciencedaily.com/releases/2011/05/110516201101.htm

Source: Sciencedaily.com