Effects Of Warming And Clipping On Growth Of Stipa Grandis

Global climate change and land use change represented by raising temperature and mowing are two important aspects of global change research. Temperature and mowing can affect plant growth and development. Understanding the impacts of mowing on plant growth and development is an important fundamental of scientific management of grassland under global warming in the future. In the present study, we used Stipa grandis as our study material to examine its response to climate warming and clipping mimicking mowing for hay at individual level. The main results showed as below:(1) Clipping had no significantly effects on most of the morphological characteristics, net photosynthetic rate, biomass accumulation and allocation, only significantly decreased specific leaf area and increased the relative growth rate of height and biomass of S. grandis, resulting in over-compensation of plant height and biomass.(2) Warming had no significantly effects on all the morphological characteristics, net photosynthetic rate, biomass accumulation and allocation, only decreased the relative growth rate of biomass of S. grandis.(3) Under warming condition, clipping significantly decreased partial morphological characteristics, biomass accumulation (leaf biomass, aboveground biomass, total biomass) and allocation (leaf biomass ratio), significantly increased root biomass ratio, root-shoot ratio and relative growth rate of plant height and biomass. Comparing with unwarming and clipping treatment, most of the morphological parameters (total leaf area, total root length, total root volume and length, surface area and volume of0.0-0.5and0.5-1.0mm in diameter of fine root), biomass accumulation parameters (leaf biomass, stem biomass and root biomass, aboveground and total biomass) and compensatory biomass of S. grandis were significantly lower in warming and clipping treatment. Our results indicate that the negative impacts on S. grandis of clipping will be exacerbated by warming.