Abstract:
Deforestation is a major threat to the conservation of biodiversity, especially within global centers of
endemism for plants and animals. Elevation, the major environmental gradient in mountain regions of
the world, produces a rapid turnover of species, where some species may exist only in narrow elevational
ranges. We use newly compiled datasets to assess the conservation impact of deforestation on threatened
trees across an elevational gradient within the Eastern Arc Mountains of Tanzania. The Eastern Arc has
suffered an estimated 80% total loss in historical forest area and has lost 25% of forest area since 1955.
Forest loss has not been even across all elevations. The upper montane zone (>1800 m) has lost 52% of
its paleoecological forest area, 6% since 1955. Conversely, the submontane habitat (800–1200 m) has lost
close to 93% of its paleoecological extent, 57% since 1955. A list of 123 narrowly endemic Tanzanian East-
ern Arc tree taxa with defined and restricted elevational ranges was compiled and analyzed in regard to
mountain block locations, elevational range, and area of forest within each 100 m elevational band. Half
of these taxa have lost more than 90% of paleoecological forest habitat in their elevational range. When
elevational range is considered, 98 (80%) of these endemic forest trees should have their level of extinc-
tion threat elevated on the IUCN Red List. Conservation efforts in montane hotspots need to consider the
extent of habitat changes both within and across elevations and target conservation and restoration
efforts throughout these ecosystems’ entire elevational ranges.
