Responses of grassland ecosystems to precipitation and land use along the Northeast China Transect

Abstract

The Northeast China Transect (NECT) has been used to study how water availability influences the composition of plant functional types, soil organic matter, net primary production, trace gas flux, and land-use patterns. We discuss relations of plant species number, soil C and N and above-ground biomass with a precipitation gradient and interactions with land-use practices (grassland fencing, mowing and grazing), on the basis of data from the west part of NECT. The results indicate: 1. The above-ground biomass of grassland communities has a linear relationship with precipitation under three land-use practices, while plant species number, soil C, and total soil N have linear relationships with precipitation under fencing and mowing; under grazing the relationships are non-linear. 2. Plant species number, soil C and total soil N have strong linear relationships with above-ground biomass under both fencing and mowing, while they seem to have non-linear relationships under grazing. 3. Land-use practices along the precipitation gradient result not only in changes in grassland communities but also in qualitative changes of their structure and function. 4. Grasslands are more vulnerable to changes in climate under mowing than under fencing, and are more capable to store C in soil and plants. 5. At a given precipitation level, number of plant species, above-ground biomass, and soil C are higher under low to medium intensity of human activities (mowing and grazing). A better understanding of how different intensities of human activities will affect the structure and function of grassland will require further research.