The Effect Of Plateau Pika Disturbance On Plant Diversity In Alpine Meadow In The Qinghai Lake Region

The plateau pika（Ochotona curzoniae）is an important component of the alpine meadow ecosystem in the Qinghai-Tibet Plateau.It changes the original inter-species relationship in the plant community,thus affecting plant diversity.At present,the studies on the relationship between plateau pika disturbance and plant diversity were either focused on species diversity or functional group diversity.However,most of the studies were conducted in only one location,what’s more,these studies ignored plant traits.The differences in time and site made it impossible to use the existing research results to consolidate the common pattern of the relationship between plateau pika disturbance and plant diversity.Plateau pika presented as a large mosaic in the alpine meadow,thus,the relationship between plateau pika disturbance and plant diversity needed to be studied through two or more locations simultaneously,which would reach a common pattern of relationship between plateau pika disturbance and plant diversity.A field survey based on the Gangcha County and Gonghe County in Qinghai Lake Region was carried out in this study to determine the effects of plateau pika disturbance on plant species diversity,functional group diversity and functional diversity of K.pygmaea meadow.The main results were:1 Plateau pika disturbances increased the plant species richness and diversity index,whereas decreased species evenness index..Plateau pika disturbance increased plant species richness and diversity index,while decreased the important value of K.pygmaea both sites.Plateau pika disturbance reduced species evenness index,and the responses of species evenness index to the plateau pika disturbance was site-dependent.Species evenness index significantly decreased in disturbed areas at Gangcha County,while was not significantly different between disturbed and undisturbed areas in Gonghe County.Meanwhile,the number of species increased was site-dependent.The number of species increased at Gonghe County was 4,while at Gangcha County was 5.2 The effects of plateau pika disturbance on the diversity were different among four functional groups.Plateau pika disturbances had no effect on the richness,evenness and diversity index of Gramineae and Leguminosae,and the richness and evenness index of Cyperaceae,while decreased the diversity index of Cyperaceae;increased the richness and diversity index of forb.However,the evenness index of forb was site-dependent,which was increased by plateau pika disturbance in Gangcha County,while was not related to plateau pika disturbance in Gonghe County.3 Plateau pika disturbance increased plant functional richness index,whereas its effects on the functional divergence index and functional evenness index were site-dependent.Plateau pika disturbances increased plant functional richness indexes FAD₂、MFAD、FDp、FDc、FRic in two sites,while the functional divergence index and functional evenness index in relation to plateau pika disturbance were site-dependent.Plateau pika disturbance decreased functional divergence index FDiv and functional evenness index FEve at Gangcha County,whereas it had no effect on these indexes at Gonghe County.4 Plateau pika disturbance altered the relationships between species diversity and functional group diversity,but changes of the relationship were not consistent between sites.The plateau pika disturbance caused the relationship between the species richness index and the richness index of Leguminosae from correlated to irrelevant at two sites.However,the plateau pika disturbance induced the relationship between the species diversity index and the diversity index of forb in Gonghe County from no correlation to be significantly correlated,while these relationships changed from irrelevant to related in Gangcha County.5 The relationship between species diversity and functional diversity under the plateau pika disturbance were consistent in two sites.The species richness and diversity index of the two sites were correlated with FAD₂,MFAD,FDp and FDc,whereas they had no correlation with with FRic.The species evenness index was correlated with FAD₂ and FRic,while it wasn’t correlated with MFAD,FDp,and FDc.The correlations between FAD₂、MFAD and species richness and species diversity index were strong,indicating that FAD₂ and MFAD can evaluate the relationship between plant species diversity and functional diversity better under the plateau pika disturbance.In summary,plateau pika disturbances on species richness and species diversity index,the diversity index of Cyperaceae,Leguminosae and Gramineae,functional richness are consistent in two sites,while the effects of species evenness index,the evenness index of forb,functional divergence index and evenness index were site-dependent.