Impacts of plateau pikas on soil organic matter and moisture content in alpine meadow

Abstract

We investigated the impact of plateau pikas(Ochotona curzoniae)on the organic content and moisture content of soil in alpine meadow.Soil samples were collected in late summer 2005 from layers up to 50 cm deep from an area where pikas were at a density of ca.50 ha-1(medium density)and from an area where no pikas were present following intensive control 18 years ago.The amount of organic matter in the soil was determined by mass loss on ignition(% by weight).Soil moisture content was determined by mass loss following drying(% by weight).In the top 10 cm of soil there was more organic matter and a higher moisture content in areas where pikas were present than where they were absent(organic matter ca.23.20% vs.ca.17.05% and ca.17.28% vs.ca.15.35%;moisture content ca.54.05% vs.ca.41.03% and ca.44.48% vs.ca.39.49%).Between 11-30 cm deep,both areas had similar soil organic matter(average ca.15.35%;ca.14.44% and ca.13.55%)and water content(average ca.39.15%;ca.37.60% and ca.34.00%).Between 31-50 cm deep there was more organic matter(ca.13.74%)in areas where pikas were present than where they were absent(ca.12.83%),but both areas had similar soil moisture content(average ca.30.40%).Our results show that medium densities of plateau pikas can promote the material cycle in alpine meadow ecosystems.