Distribution Pattern Of Butterfly Diversity Along An Elevational Gradient In Mt.Tianmu,Zhejiang Province

Mountain serves as the “natural laboratory” for elevational patterns of biodiversity studies,which huge variations of environmental factors among elevation drive the complex and changeable patterns of the diversity in biological taxa and the trends in morphological traits,such as body size.Previous studies explored biodiversity along elevational gradients,with the large focus on plants and birds.However,much is less know about butterfly.As an important indicator of environment,especially in subtropical forests,exploring butterfly diversity pattern and its underlying mechanism along elevation can promote butterfly conservation in subtropical forests and assessment of biodiversity effected by environment.This study was conducted butterfly survey at twelve 20 m × 20 m plots that varied in elevation from 367 m to 1474 m a.s.l.for 26 samples during April-September from2018 to 2020 in Tianmu Mountain National Nature Reserve,Zhejiang Province.Using trapping nets within rotten banana and fish at 2 m and 8 m canopy heights,I collected 1067 individuals of 62 species in 31 genera and 3 families and measured their body size(forewing length,width,wingspan and body length as the surrogates of body size)of butterfly dominant genera.Combined the climatic and topographical data,I examined how butterfly richness and abundance was distributed by elevation and microhabitat,and how body size responded to microclimate along elevational gradient in Mt.Tianmu.The conclusions are as follows:(1)In Mt.Tianmu,species richness and abundance patterns of butterfly followed an approximate U shape,which first decreased from 427 to 944 m and sharply increased to a peak at 1329 m.In terms of annual dynamics,high butterfly diversity occurred in 2018,with a total of 525 in 25 genera and 40 species.Regarding to the seasonal dynamics,butterfly diversity gradually increased to reach a maximum of 624 in 27 genera and 43 species in July,and then decreased after August.(2)In whole elevation range,slope and aspect effected strongly on distribution pattern of butterfly diversity.The slope had negative correlations with butterfly richness and abundance,but aspect was positively related with them.There was no significant correlations among butterfly diversity,climate and plant diversity.(3)At medium and low area(367-944 m),host and woody plants diversity had strongly negative impacts on decreased pattern of butterfly diversity,while the mean DBH of woody plants was positively correlated with it.It indicated that plant as a primary producer shape the species composition of butterfly.However,at medium and high area(944-1474 m),increased pattern of butterfly diversity had no correlations with any climatic,topographical and vegetative variables.(4)In different vegetation types and forest vertical structures,butterfly tended to gather in canopy(8 m)of evergreen broad-leaf forest and dwarf shrub,indicating that butterflies fit in open-canopy forests with more sunlight.Moreover,correlation analysis showed butterfly diversity in canopy was mainly related with aspect and host plant diversity,slope and aspect highly correlated with butterfly in understorey.(5)Supported to “Bergmann's Rule”,body size of Neope in dominant genus were significant bigger with the increasing elevation,which is affected by the air temperature and humidity.Neope survived in colder regions of high elevation by reducing heat loss with the bigger body.However,there were no obvious elevational patterns in body size of Penthema,Lethe and Euthalia,indicating that different species have different mechanisms in response to climate change.In summary,this study conducted a preliminary exploration of the elevational pattern of butterfly diversity in Mt.Tianmu,and showed that habitat heterogeneity of topography,vegetation types and forest vertical structures,variations of plant diversity are important variables effected elevational pattern of butterfly diversity.Butterfly adapted well to the climatic conditions among elevations through their body size,but there existed differences between different species.Our results provide a scientific basis for understanding and predicting how butterfly diversity responds to environmental changes.