Relationships between plant colonization and soil characteristics in the natural recovery of an earthquake-triggered debris flow gully in the Wanglang National Nature Reserve, China

Fragmentation and loss of habitats due to natural disasters, like earthquakes and earthquaketriggered debris flows are existing threats to the longterm survival of the giant panda (Ailuropoda melanoleuca). To better understand natural recovery processes of the damaged habitat, field investigation and laboratory analysis were used to analyze relationships between plant colonization and soil characteristics in an over 30-year natural recovery of a damaged giant panda habitat in a debris flow gully after the 1976 Songpan-Pingwu earthquake in Sichuan Province, China. Four different damaged sites were selected that located at the center of the gully (center), on a flat alluvial fan (fan), in a side slope of the gully (slope), and at the ecotone between the gully and native forest (ecotone). Vegetation characteristics, soil physicochemical properties, and microbial biomass in the different sites and soil depths were measured. After the natural recovery, the soil fertility, water retention, and microbial biomass were highest at ecotone, followed by fan, slope, and center. Only a few perennial herbs colonized at center; shrubs started to invade at fan and slope, and the native trees dominated the community of ecotone. Furthermore, Fargesia spathacea (food for the giant panda) started to be re-established at ecotone, and the community characteristic of ecotone recovered similarly to the native habitat. These results suggested that improving the soil fertility, water retaining capacity and microbial biomass is fundamental to the plant colonization, particular for F. spathacea’s reestablishment in a damaged giant panda habitat.