The Diversity Of Butterflies In Nanning Urban Green Landscape

With the rapid development of urbanization,the natural environment has been affected by various impacts,and the biodiversity has also changed.In order to explore the impact of urbanization on biodiversity,this study selected20 different urban green landscapes in Nanning and divided them into three urbanization gradients(urban center area,urban buffer area and urban fringe area)according to the distance between urban green landscapes and urban center.In this study,the transect method was used to investigate the butterflies in the plot for three times from May to September 2022.At the same time,the plants on both sides of the transect,the number of tourists encountered and the use of pesticides were comprehensively investigated.The 20 urban green landscapes were classified and their landscape pattern metrics were calculated.The differences in species diversity of butterfly communities in different gradients were analyzed by independent sample t test to explore the effects of urbanization level on butterfly communities in different gradients.Simple linear regression,Pearson correlation analysis and multiple linear regression were used to explore the relationship between butterfly abundance and plant species,landscape pattern metrics and garden management behavior.Based on the above conclusions,suggestions on the planning and management of butterfly friendly urban green landscape are put forward.The main research results are as follows:(1)A total of 4895 butterflies were recorded in the study area,belonging to 8 families,72 genera and 120 species.Nymphalidae had the largest number of genera and species.The Oriental butterflies dominate the urban green space in Nanning.The number of butterfly species increased from the urban center area to the urban fringe area,but the number of butterfly individuals in the urban buffer area was the largest.The results of One-way ANOVA showed that there were significant differences in ACE indices among different gradient butterfly communities(p=0.001).The order of species diversity of gradient butterfly in Nanning was urban fringe area>urban buffer area>urban center area.The variation of functional diversity of butterfly community was basically consistent with that of species diversity.(2)The number of species of oligophagous butterflies was the largest,followed by polyophagous butterflies and monophagous butterflies.Most of the observed butterfly species were flower visiting butterflies,followed by scavenging butterflies,and both flower visiting and scavenging butterflies were the least.The number of plant species was positively correlated with butterfly abundance(simple linear regression,R~2=0.469,p=0.00052).Pearson correlation analysis showed that the abundance of butterfly was affected by the abundance of various plants.For example,there was a significant negative correlation between Lagerstroemia speciosa and Eurema hecabe,and between Bischofia javanica and Elymnias hypermnestra(p<0.01).(3)The redundancy analysis of landscape pattern metrics of urban green space in Nanning showed that SHEI was the most important factor affecting butterfly community structure(p=0.004).It was followed by PLAND.Grass(p=0.049),SHDI(p=0.011)and DIVISION(p=0.013).Simple linear regression analysis showed that butterfly abundance was negatively correlated with the number of tourists(R~2=0.241,p=0.016)and the use of pesticides(R~2=0.191,p=0.031).Multiple linear regression analysis showed that the number of plant species has the greatest influence on butterfly abundance(p=0.00087),and the increase of plant species was conducive to the increase of butterfly abundance.The number of tourists also had a significant negative effect on butterfly abundance(p=0.032).In conclusion,it can be seen that with the increase of urbanization,the diversity of butterflies gradually decreases.In addition,the number of plant species,the number of tourists and the use of pesticides were also significantly correlated with butterfly diversity.The number of plant species was beneficial to butterfly diversity,while the number of tourists and the use of pesticides had adverse effects on butterfly diversity.The correlation between landscape pattern design and butterfly diversity was weak.The results of this study are of great significance for the conservation of urban biodiversity,and three suggestions are put forward based on the research results:a.Increase the allocation of host plants and nectar source plants;b.Reduce the use of pesticides and take relevant measures in advance if necessary;c.Increase landscape heterogeneity.It is hoped that these suggestions will provide a reference for mitigating the negative impact of urbanization.