Interspecific Relationships In Alpine Meadow Plant Communities:Pollinator-Mediated Interactions And The Effect Of Grazing

The studies of plant-pollinator networks showed that most of plant species always pollinated by multiple pollinators.The pollen of pollinator carried will determine the pollen load on the stigma.The effect of inter-species pollen transfer,caused by shared pollinators among plant species,on pollen receptor plant species could be positive,negative or neutral.The grazing and ungrazing plots of alpine meadow were compared to examine the effects of pollinator-mediated interspecies pollen transfer on plant-plant interaction,as well effects of plants traits and grazing on pollen transfer network in eastern edge of Qinghai-Tibetan Plateau.The results showed that 1)in the study plots,most of plants species received pollen from more than 3 species,as well export pollen to more than 3 species.The effects of HP deposition on CP deposition are mainly positive or neural for each receptor species,while the inter-species pollen transfer networks were predominated by neutral plant-plant interactions.2)The total pollen load and proportion of CP are significate positive correlated with plant height,but the HP load and HP kinds are significate negative correlated with flower number.Compared to the species with bilateral symmetry flowers,the species with radial symmetry flowers receipt larger quantity and more kinds of HP.Both plant and flower density are no effect on in-and out-degree.3)The lower height of plant individuals in grazing plots could explain the results of the reduced total pollen and CP load we detected in grazing plots.However,flower number and size were not difference between grazing and ungrazing plots,which resulted in no difference on HP quantity and kinds between grazing and ungrazing plots.In addition,the HP load of species with bilateral symmetry flowers is larger in grazing plots.In grazing plots,plants trend to receipt more less of HP,the proportion of pollinator-mediated positive effects reduced,yet the proportion of positive plant-plant interaction of pollen transfer networks increased.