Tourism effect on species composition and diversity of understory plants in Abies fargesii var.faxoniana forest in Jiuzhaigou, Sichuan
旅游干扰对九寨沟冷杉林下植物种类组成及多样性的影响

In recent years, tourism has developed rapidly in Jiuzhaigou Nature Reserve, which has been des- ignated a World Heritage Natural Site. To measure the effect of tourism on vegetation in Jiuzhaigou, we se- lected two scenic spots, namely the Virgin Forests and the Grass Lake, as study sites and compared the spe- cies composition and diversity of understory plants in Abies fargesii var. faxoniana forest. The results showed that (1) the species composition and their frequency were significantly impacted by tourism. Some native shade-tolerant or hygrophilous plants had disappeared, while some xerophilous, disturbance-resistant species, as well as some exotic and synanthropic species, had expanded their populations. (2) In the Virgin Forests, the coverage of understory plants was reduced and the shrubs and bryophytes were markedly depressed (both in height and density). In the Grass Lake, which was only slightly disturbed, there were no obvious effects on herbaceous and shrub communities except for bryophyte. It is concluded that bryophytes are more sensitive to the degree of tourism disturbance, and the species composition can be a better indicator for disturbance degree than other indices such as height, coverage and density. The results indicate that tourism in Jiuzhaigou had an obvious negative effect on the indigenous biodiversity, and conflicted with biodiversity conservation. Therefore, it is necessary to restrict tourism activities to an appropriate extent.