Respones Of Three Dominant Species Functional Traits To Grazing Intensity And Simulated Precipitation

Typical grassland is the main body of natural grassland in Inner Mongolia,and it is an important ecological barrier and animal husbandry production base in north China.The typical grassland is characterized by fragile ecological and environmental conditions,strong human disturbance,and the normal functioning of ecosystem structure and function is easily affected by grazing activities and precipitation changes.This paper analyzes the response mechanism and adaptation mechanism of typical grassland plant individuals,communities,populations and ecosystems to precipitation under the condition of global and regional rainfall pattern changes.To explore different precipitation treatment on the influence of typical grassland plant functional traits,this paper takes sheila Mu Ren grassland of Inner Mongolia three grazing intensity degree(LG light grazing,medium grazing and heavy grazing MG HG)sample area of the needle was dominant species-S.krylovii,C.squarrosa and C.ammannii as the research object,on the basis of the region determination value after years of average rainfall of 285 mm,the three kinds of grazing intensity sample respectively set up five simulated precipitation enhancement processing,Rainfall is 0 mm(CK),60 mm(W1),100 mm(W2)and 80 mm(W3)and 120 mm(W4),under different grazing intensity degree and precipitation treatment for three dominant plant morphological characters,leaf structure character and photosynthetic physiological properties are measured,discusses the three advantages of formal features of pasture degradation and precipitation treatment response,expounds three advantages of grazing intensity and the precipitation enhancement processing plant functional traits to adapt to,reveal advantage plant precipitation increase adaptation strategies for the future,In order to provide the basis and practical guidance for the healthy operation of ecosystem,rational utilization of grassland resources and scientific planning and management of typical grassland.The main research results are as follows:(1)The plant height and above-ground biomass of the three dominant plants increased first and then decreased with the precipitation gradient.In the slightly degraded plots,the functional characters of the three plants were the best when W3(rain-increasing 100mm)was used,and the plant height and above-ground biomass of the three plants were 76.8%,27.9%,63.3%,77.7%,324.7% and 96.5%,respectively.In moderate and severe degradation in the sample area,three plants are W2(80 mm)precipitation reach maximum when the plant height and above-ground biomass,gram s.grandis in moderate degradation sample area plant height growth was 96.1%,and the severe degradation in the sample area aluminium spend the largest rise in plant height,increased by 51.6%,rough implicit son grass aboveground biomass in moderate and severe grazing intensity in the sample area increased by 313.9% and 360.5% respectively.(2)With the increase of water gradient,the net photosynthetic rate and water use efficiency of the three plants increased first and then decreased.The increase of precipitation had a certain improvement effect on the photosynthetic siesta of the three plants and delayed the first peak.The net photosynthetic rate of the three plants was the maximum when the precipitation increased to 100 mm in the mildly degraded sample plots.The maximum precipitation increase was 80 mm in the heavily grazed degraded sample land.In the moderately degraded grazing plots,the best growth of S.krylovii and C.squarrosa was found at precipitation of 100 mm and the best of C.ammannii at precipitation of 80 mm.(3)The leaf anatomical structure of three kinds of plants in the grassland varied greatly under five kinds of rainfall enhancement treatment in the sample land with different grazing intensity.In different grazing plots,the thickness of leaf,cuticle and main vein decreased gradually with the increase of precipitation gradient,and the vascular bundle area/leaf area increased first and then decreased in each grazing plot, and decreased obviously with the increase of rainfall.Under the three grazing intensities,the leaf structure characteristics of plants in the heavily grazed plots were the most sensitive to the change of water environment,and the variation range was the largest.In contrast,the leaf structure characteristics of S.krylovii and C.ammannii are more responsive to environmental changes.(4)The effects of grazing intensity and precipitation on the growth and physiological characteristics of the three plants were significantly different.The increased rainfall was negatively correlated with the above-ground biomass of S.krylovii,and positively correlated with the above-ground biomass of C.squarrosa and C.ammannii.The leaf thickness of the three plants was negatively correlated with the precipitation treatment,and positively correlated with the net photosynthetic rate and water use efficiency.Grazing intensity was negatively correlated with above-ground biomass,net photosynthetic rate and water use efficiency of the three plants.In conclusion,MAO's needle,rough implicit grass and physiological ecology characteristics of silver grey spin flower would have made a positive response to the simulated precipitation,suggested that under the condition of the conditional appropriate precipitation 80-100 mm,to promote plant growth and development,enhance the capacity of carbon assimilation,accumulate more photosynthetic product,for the local soil nutrient accumulation,vegetation construction and ecological restoration.