Soil restoration potential with corridor replanting engineering in the monoculture rubber plantations of Southwest China

Corridor engineering is a common approach for wildlife conservation. The influence of the practice on soil properties including nutrients and organic matter, however, remains poorly investigated. In order to predicate the long-term effects of Asian elephant (Elephas maximus L.) conservation corridors (AECC) of the Greater Mekong Sub-region (GMS) on soil properties and functional recovery, we studied the soil comprehensive accumulation ability and estimated total recovery time under two major forest types on which the corridor is built (natural secondary forest and rubber plantation) and one forest type generated by ecological replanting on existing rubber plantation in comparison with soils under primary rain forest and fallow land in Xishuangbanna, Southwest China. Soil samples were taken from five research sites and fifteen soil properties were measured.On a 30-year basis, soil recovery differed significantly in the three regimes. The natural secondary forest regime had the highest comprehensive accumulation of about 92% and the shortest estimated recovery time (37-40 years). In contrast, the monoculture rubber plantation, despite constant fertilizer and management input, yielded the poorest recovery result of about 75% and the longest recovery time (95-100 years). From the perspective of soil recovery, this regime appears unsustainable. However, the ecological replanting using local rain forest trees and shrubs thereby to build forest structure complexity and diversity on the monoculture rubber plantation improved comprehensive accumulation ability of about 8% (from 75% to 83%) and shortened the recovery time (40 years). The results suggest that the corridor engineering by natural secondary forest regime or by ecological replanting of monoculture rubber plantation can serve as effective regimes for soil properties recovery.