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

为揭示旅游活动对自然保护区生态环境的影响,作者选择九寨沟原始森林与草海两个景点,分别调查了每个景点内旅游干扰地段与未干扰地段岷江冷杉(Abiesfargesiivar.faxoniana)林林下植物种类组成的数量特征(重要值、频度、密度、盖度和高度)及物种多样性,分析了干扰对林下植物种类组成与物种多样性的影响及其差异性。结果表明:(1)旅游干扰显著改变了林下植物物种组成:耐荫喜湿的乡土植物局部消失,而喜旱耐扰动的植物种群扩大,外来和伴人植物种群侵入。(2)在原始森林景点,较重的旅游干扰明显降低了灌木与苔藓植物的频度和盖度,显著抑制了灌木与苔藓植物发育(高度、密度降低);在草海景点,较轻度的干扰只抑制了苔藓植物盖度,而灌木与草本植物没有受到显著影响,表明苔藓对旅游干扰强度更为敏感,同时也表明群落物种组成可以比频度、高度、盖度和密度更好地表达群落受干扰程度。综合分析表明,九寨沟旅游干扰与世界自然遗产保护目标即生物多样性保护有明显冲突,需要进一步强化管理,限制旅游干扰活动。

Tourism effect on species composition and diversity of understory plants in Abies fargesii var.faxoniana forest in Jiuzhaigou, Sichuan

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.