Response Of Species Diversity And Productivity To Different Stocking Rates In The Stipa Breviflora Desert Steppe

The relationship bet ween species diversity and productivity in grassland ecosystem is a hot topic in recent years.As a special grassland type the desert steppe is characterized bylow precipitation,deficient soil nutrients,and relatively simple plant community structure.Therefor e,studying the relationship between plant diversity and pr oductivity is necessary to maint ain the conservation of biodiversity and development of ani mal husbandry in the desert steppe.The study site is located at a Stipa breviflora desert steppe in Siziwang Banner of Inner Mongolia.Ba sed on the individual scale of the plants,the relationships between species diversity and aboveground productivity,as well as functional group diversity and aboveground productivity in plant community were analyzed with a field experiment from2016 to 2017.The responses of plant diversity and productivity to the stocking rates[0?CK?,0.91?LG?,1.82?MG?,2.71?HG?sheep unit/(hm²·half year^-1)]were studied in this paper.The major findings are as follows:1.In the two growing seasons from 2016 to 2017,The plant species,with13 families and 30 species in two years.Among these stocking rate plots,most of the species reduced with the increasing stocking rates.Due t o the decline of Chenopodi aceae plants,the number of species in 2017 decr eased by 16.7%,17.2%,5%,11%under four stocking rate treatments comparing with in 2016,respectively.2.During the two-year trial period,we anal yzed from the perspective of life function group,perennial grasses has the largest share of plant communities and increases with stocking rates;From photosynthetic functional group analysis in desert steppe,C₃ plants accounted for more than the proportion of C₄ plants.3.The nested square results showed the logar ithmic model y=a Ln?x?+b was appropriate to describe the curve of t he species-area relationship in desert steppe species,the number of species increased with the size of sampling area.The mini mum sampli ng area for all stocking rate treatmentswere 16m×16m in2016?wet year?.I n 2017?drought year?,the mi ni mum sampling area gradually decreased from the CK to HG treatment,with 8m×16m,8m×16m,8m×8m and 8m×4m for four treatment s,respectively.4.The ANPP was the highest under CK tr eatment,and decreased with increasing stocking r ate.Moreover,the ANPP in 2016 was higher than that of2017 within all stocking rates treatments.In addition,BNPP had a opposite trend with ANPP,but the BNPP in 2017 was significantly lower than that of2016..5.Grazing significantly reduced the species diversity,even though no significant difference was found in Pielou's index in 2017.The Margalef's index showed no significant response to stocking rate.However the Shannon-Wiener and Pielou's evenness indices showed the decreasing trends with increasing stocking rate..6.In the desert steppe,the Margelaf's,Shannon-Wi ener and Pielou's indices had significant positive correlation with aboveground productivity in the plant community?P<0.05?.However,there was no unifor m relationshi p between functional group diversity and grassland productivity was found in this study.