Canopy Rainfall Interception Capacity And Its Influential Factors Of Typical Grassland Communities In The Loess Hilly-gully Region

The interception of vegetation canopy is an important hydrological process in the distribution of rainfall,and it is of great significance to clarify the canopy rainfall interception characteristics of grassland community and its influencing factors to reveal the environmental effects of ecological restoration.In this paper,three typical grassland vegetation communities（Bothriochloa ischaemum,Lespedeza davurica and Artemisia sacrorum）were selected as the research objects and three rainfall intensity(0.5,0.7 and 0.9 mm·min^-1)was set up in the loess hilly-gully region.During June-September 2019,artificial rainfall and community plots were simulated,we have investigated the relationship between the characteristics of canopy rainfall interception in different grassland communities and the above-ground biomass,vegetation coverage,leaf area index,community diversity index,and rainfall characteristics of vegetation communities.The purpose of this study was to explore the effects of community characteristics and rainfall characteristics on rainfall interception capacity of grassland community canopy,so as to scientifically evaluate the influence of vegetation restoration on rainfall interception and its eco-hydrological effect in the Loess Hilly Region.The main results are as follows:（1）From June to September,the canopy rainfall interception capacity ranges of B.ischaemum communities,L.davurica communities and A.sacrorum communities were 0.58-0.75 mm,0.65-0.82 mm,and 0.69-0.87 mm,respectively,and the canopy rainfall interception rates are 7.88%-10.35%,8.85%-11.27%,and 9.39%-11.95%.From June to September,canopy rainfall interception capacity and interception rate of three grassland communities showed a trend of first increasing and then decreasing,and all reached the maximum values in August,which were 0.75 mm and 10.35%,0.82 mm and 11.27%,and 0.87 mm and 11.95%,respectively.In the four months,the intercessory capacity and intercessory rate of A.sacrorum communities were followed by L.davurica communities,and B.ischaemum communities was the smallest.（2）There were significant positive correlations between canopy rainfall interception capacity and above-ground biomass,vegetation coverage and leaf area index of grassland communities in three different grassland communities.Among them,the correlation coefficient of canopy rainfall interception capacity of B.ischaemum communities and A.sacrorum communities with aboveground biomass was the highest（r=0.81and 0.79）.The correlation coefficient between canopy rainfall interception capacity of L.davurica community and coverage was the highest in davurihu community（r=0.81）.There was no significant correlation between the canopy rainfall interception capacity of the three grassland communities,community species richness,Simpson dominance index,Pielou evenness index and Shannon-Wiener diversity index.（3）With the increase of rainfall intensity,the canopy interception capacity of the three grassland communities showed a trend of increasing first and then decreasing,and the interception rate showed a trend of decreasing gradually.Among them,rainfall interception capacity was the largest under the condition of rainfall intensity of 0.7 mm/min,which was 0.77,0.81 and 0.85 mm respectively.The interception rates of canopy rainfall were the highest under the condition of rainfall intensity of 0.5mm·min^-1,which were 8.69%,9.41%and 10.19%,respectively.With the extension of rainfall time,the canopy rainfall interception of three different grassland communities showed a changing pattern of rapidly increasing and then gradually stable at last,while the interception rate showed a changing pattern of rapidly decreasing and then gradually stable at last.