The Impacts Of Tourism Disturbances On Plant Diversity And Soil Microbial Diversity Of Laoshan Mountain

Nature reserves with rich biodiversity are becoming major tourist destinations with the rapid development of nature-based tourism.The combination of ornamental plant introductions to attract tourists,tourist activities and habitat factors has become important factors affecting wild plant diversity and soil microbial diversity in the reserve,particularly the narrow areas along walking trails.Therefore,understanding of how plant introductions,tourist activities and habitat factors affect plant diversity and soil microbial diversity is crucial to manage tourism disturbances and to conserve biodiversity.In this study,the areas along walking trails in Qingdao Laoshan Nature Reserve were taking as Disturbed Area,and the fenced core area and buffer area were taking as Control Areas.The tourist number per 10 minutes,introduced species richness and abundance of ornamental plants were taking as tourist disturbance factors.The effects of tourism disturbance and habitat factors on plant diversity and soil microbial diversity in the Disturbed Area have been revealed.Totally 24 and 10 plant community plots of 50m×2m along the walking trails have been sampled randomly in the Disturbance Area and the Control Area,respectively.Tourism disturbance factors,habitat factors,plant community composition,plant diversity survey and soil sampling were conducted at each plot.Four types of plant diversity indices including species richness,species diversity,phylogenetic diversity and phylogenetic structure,and soil microbial diversity indices were calculated.Based on the survey data,the influences of tourism disturbances on habitat factors were analyzed using simple linear regression.The differences of plant diversity in total plant communities and different layers between Disturbed Area and Control Areas were revealed by ANOVA.The dominant factors affecting plant diversity indices were revealed by multiple stepwise regression analysis.Eventually,the relationships between tourism disturbance factors,habitat factors,plant diversity and soil bacterial and fungal diversity indices have been uncovered by Spearman correlation analysis.Otherwise,PCoA(Principal Co-ordinates Analysis)and db-RDA(Distance-based redundancy analysis)analyses were conducted to explore the possible pathways through which tourism disturbances affect soil microbial diversity.The main conclusions are as follows:(1)Tourism disturbances have significant effects on soil physicochemical properties and plant community characteristics in Laoshan.As passing tourist number per 10 minutes increased,soil total nitrogen,soil total phosphorus and soil organic carbon contents as well as shrub layer cover and herb layer height decreased significantly and soil pH increased significantly.Soil total nitrogen,soil total phosphorus and soil organic carbon content decreased significantly with increasing ornamental plant introduction species richness.As introduced species abundance of ornamental plant increased.soil total nitrogen and total pho sphorus levels decreased significantly.(2)The ANOVA showed that the partial diversity indicators of the shrub and herb layer in the Disturbed Area were remarkably lower than those in the Control Area,and tourism disturbances had significant impacts on the plant diversity of shrub and herb layer.Multiple stepwise regressions showed that shrub layer species richness,species diversity indices and phylogenetic diversity index were negatively collinear with the tourist number per 10 minutes.Species richness,species diversity indices and phylogenetic diversity index of the herb layer were negatively and dramatically associated with the introduced species abundance.The introduced species richness were positively correlated with species diversity indices of the herb layer.Additionally,the NRI index of herb layer were positively correlated with introduced species richness and the tourist number per 10 minutes,but negatively correlated with introduced species abundance.Thus,the tourist number per 10 minutes had significant effects on plant species richness,species diversity and phylogenetic diversity of the shrub layer,and introduction of ornamental plants had significant impacts on species richness,species diversity and phylogenetic diversity of herb layer.Both the tourist number per 10 minutes and introduction of ornamental plants affected the phylogenetic structure of the herb layer,caused the NRI index of the herb layer to converge to zero.That meant the plant communities to be assemblied randomly,which supported the neutral theory.(3)Among the tourism disturbance factors,the effect of tourist number per 10 minutes on soil microbial diversity was more obvious.The db-RDA results revealed that the tourist number per 10 minutes and soil pH were the primary elements shaping species composition of soil bacterial and fungal communities.The tourist number per 10 minutes and increased soil pH resulted in higher abundance of Bacteroidetes,Firmicules,and Ascomycota,and lower abundance of Verrucomicrobiota.Spearman showed that the Shannon-Wiener index of soil bacteria was positively related to soil pH.The Simpson index of soil fungi was found to be positively related to soil pH,but negatively correlated with shrub layer plant species richness.Shannon-Wiener index and Simpson index.In summary,this study revealed the combined effects of tourists,introduction of ornamental plants and habitat factors on wild plant diversity and soil microbial diversity along the walking trails of the Laoshan Nature Reserve.The key influencing factors were identified as the tourist number per 10 minutes,species richness and abundance of ornamental plant introductions,soil pH.And the direct and indirect effects of tourist disturbances on plant diversity,as well as on soil microbial diversity and community composition were explained.It was found that tourist number per 10 minutes had a significant effect on shrub layer plant diversity and soil microbial community,and ornamental plant introductions had a significant effect on herb layer plant diversity.The tourist number per 10 minutes and soil pH are the dominant drivers of soil bacterial and fungal diversity and community composition.The relevant results can provide new insights into scientific management of tourism disturbances,conservation of plant diversity and soil microbial diversity in mountainous Nature Reserves.