GeoWorld July 2012

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1.4; rivers, canals and lakes data from Digital Chart of the World; and a digital elevation model (DEM) from the Shuttle Radar Topographic Mission version 4, available from the International Center for Tropical Agriculture. The full list can be found in the PLoS ONE paper, Appendix 3. The GIS-based variables used to model the probability of tiger occupancy include the following: condition in 2007. each 17- by 17-kilometer grid cell. areas equal to or greater than 50,000 hectares (124,000 acres) based on conditions in 2005. Needs for Conservation Although the Indonesian government set aside many areas and national parks for the conservation of endan- gered species, about 70 percent of tiger habitat in Sumatra remains outside these protected areas. Study authors emphasize that the preservation of such habitats, which requires support from government, landowners and concession holders, is critical for conserving the species. too small for their habitation and causing inbreed- death. Riparian forest corridors must be created in the fragmented landscape, and tree plantations should include understory growth if tigers are to survive. "Even with current legal protection for the species, tigers are not doing well in many places, especially those outside protected areas," added Sunarto. "As long as forest conversion continues, tigers will require active protection, or they will quickly disappear from our planet." "These results indicate that to thrive, tigers depend on the existence of large contiguous forest blocks," said study co-author Marcella Kelly, an associate forests for plantations. "We hope that plantation managers and concession owners can use the recommendations of this report to apply best-management practices to further protect Sumatran tigers from extinction," said Anwar Purwoto, A recently published Indonesian presidential decree on land use in Sumatra notes the importance of build- Su Clauson-Wicker is a writer and Lynn Davis is Public Affairs director for Virginia Tech's College of Natural Resources and Environment; e-mail: and, respectively. JUL Y 2O12 / WWW . GEOPLA CE . COM 17 A spatially explicit map model shows where tiger populations are likely. ing wildlife corridors between critical areas, where commitments from concession owners are key to suc- cessful implementation. "Ensuring that tigers are able to roam freely in natural forests and restored habitat is crucial to their survival," said co-author Sybille Klenzendorf, head of forests that tigers and other animals rely on." Tigers occupy only about 7 percent of their historic range. There are estimated to be as few as 3,200 tigers left in the wild, and fewer than 400 Sumatran tigers, which are listed as critically endangered on the International Union for Conservation of Nature Red List of Threatened Species ( redlist/details/15966/0). tiger populations is a good thing," noted Sunarto, "but success depends on everybody—the companies, the governments and the people."

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