6 research outputs found
Understanding the impacts of land-use policies on a threatened species: is there a future for the Bornean orang-utan?
The geographic distribution of Bornean orang-utans and its overlap with existing land-use categories (protected areas, logging and plantation concessions) is a necessary foundation to prioritize conservation planning. Based on an extensive orang-utan survey dataset and a number of environmental variables, we modelled an orang-utan distribution map. The modelled orang-utan distribution map covers 155,106 km(2) (21% of Borneo's landmass) and reveals four distinct distribution areas. The most important environmental predictors are annual rainfall and land cover. The overlap of the orang-utan distribution with land-use categories reveals that only 22% of the distribution lies in protected areas, but that 29% lies in natural forest concessions. A further 19% and 6% occurs in largely undeveloped oil palm and tree plantation concessions, respectively. The remaining 24% of the orang-utan distribution range occurs outside of protected areas and outside of concessions. An estimated 49% of the orang-utan distribution will be lost if all forest outside of protected areas and logging concessions is lost. To avoid this potential decline plantation development in orang-utan habitats must be halted because it infringes on national laws of species protection. Further growth of the plantation sector should be achieved through increasing yields in existing plantations and expansion of new plantations into areas that have already been deforested. To reach this goal a large scale island-wide land-use masterplan is needed that clarifies which possible land uses and managements are allowed in the landscape and provides new standardized strategic conservation policies. Such a process should make much better use of non-market values of ecosystem services of forests such as water provision, flood control, carbon sequestration, and sources of livelihood for rural communities. Presently land use planning is more driven by vested interests and direct and immediate economic gains, rather than by approaches that take into consideration social equity and environmental sustainability
This figure shows the results of the jackknife procedure on the full Maxent model.
<p>This figure shows the results of the jackknife procedure on the full Maxent model.</p
Contextual layers used for the generation of the orang-utan distribution.
<p>Note: Layer correlations (Using ENMTools <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0049142#pone.0049142-Warren1" target="_blank">[84]</a>) were lower than 0.5 except for elevation with slope and rugosity. All three layers were maintained in the final analyses since they are of different importance for orang-utans.</p
Orang-utan distribution area in protected areas and concessions.
<p>Note: Areas in this Table are expressed in km<sup>2</sup>. IOPP: industrial Oil Palm Plantation; ITP: Industrial Timber Plantation.</p><p>For Sabah data on oil palm plantations concessions were not available.</p
Overview maps of forest cover and orang-utan data points in combination with the orang-utan distribution and land use types.
<p>a) Remaining forest cover in 2010. The sample of 558 orang-utan points used to model habitat is shown. b) Concessions and protected areas in 2010, c) The modelled orang-utan spatial distribution. d) Orang-utan distribution and overlap with protected areas and concessions.</p
Contributions of contextual layers to orang-utan Maxent model.
<p>Note: validation model values are the mean, min-max values from a 10 fold validation model ran with the same data in Maxent.</p