Study On Seasonal Changes In Mound Features Of Plateau Zokor

As an important component in alpine meadow ecosystem,the increase of population of plateau zokor often gives rise to a large number of soil mounds on grassland.These mounds will cause severely impair on grassland ecosystem production.For this reason,the ecological researchers of alpine meadow had pay great attention to the biological and ecological prevention of plateau zokor.In this research,by using field survey,the seasonal changes of quantity,shape,and the distribution patterns of zokor mound were investigated.The main results are as follow:(1)The density of zokor mound changed significantly in different seasons,and showed a sequence as follows: autumn > spring > summer.In the total mound of three seasons,there was also significant difference between three kind of mound(small-sized,medium-sized and large-sized mound).The average mound in autumn was 198.67,among which small ones occupied 63.84 %,medium ones occupied 28.01 %,and large ones occupied 8.15 %.The average mound in spring was 107.33,among which small ones occupied 32.00 %,medium ones occupied 52.93 %,and large ones occupied 15.07 %.The average mound in summer was 44.67,in which small ones occupied 92.55 %,medium ones occupied 7.45 %,and there was no large ones.(2)The base radius and the height of the mound are two important factors affecting the volume of mound.There was a significant difference in mound radius between spring,summer and autumn.The change sequence of radius are autumn > spring > summer.The mound height,however,has different change patterns.There was no significant difference in mound height between spring and autumn.But there existed obviously difference in mound height between spring,autumn and summer.The volume of zokor mound also changed obviously with seasons.The change pattern was similar to that of mound height,ranged successively as autumn,spring and summer.Corresponding to the change of mound volume,the mound coverage also changed significantly with the seasons and act as 11.01 % in autumn,7.44 % in spring,and 1.32 % in summer respectively.(3)The results of clumping index calculation indicated that there was significant difference in distribution pattern of zokor mound between spring,summer and autumn.In spring and autumn,the zokor mound appeared a clumping distribution pattern,and the clumping intensity of autumn was stronger than that of spring.In summer,however,it closed to a random distribution pattern.The result of linear-regression analysis indicated that there was a significant positive correlation between clumping index and mound density of plateau zokor.