Distribution Pattern Of Alien Plants Along Recreational Routes In Laojun Mountain National Park

Nowadays, the biological invasion has become one of major environmental problems around the world. Meanwhile, with economic development, more and more people are involved in tourism activities. The dispersal of alien plants resulted from tourism activities should be concerned, particularly for protected areas in mountainous areas which have fragile ecological environment and important conservation values. A national park in Northwest Yunnan, Laojun Mountain Area, was chosen to study the effect of tourist-mediated dispersal of alien plants along recreational routes. Using data from vegetation surveys and germination experiments of seed bank, we first examined the distribution of alien plants along recreational routes in the park. Then, the ordination method (canonical correspondence analysis, CCA) was employed to determine which environmental factors mostly influenced distribution pattern of alien plants along routes. Finally, with multiple comparison analysis (ANOVA), we compared the different effects of tourism usage frequencies and route types upon the distribution of alien plants in the park. The results were shown as follows:1. The vegetation surveys showed total of 35 alien plants were recorded in the park, which belong to 15 families and 27genus. The dominate family was Composite, Solanaceae, Amaranthaceae, Chenopodiaceae and Leguminosae. Most aliens originated from America and Europe. Herbs mostly presented with 8 perennial and 22 annual. The germination results from seed bank demonstrated that seeds of seven new alien plants had already existed in park soils along routes but they don’t successfully established population in natural environment.2. CCA result showed that altitude and travel distance (from park entrance) were key environmental factors that affected alien plants distribution along recreational routes in the park. Explanatory degrees of two factors were high to 43.4% and 21.5%, respectively. Meanwhile, slope and aspect were shown not to significantly relate to alien distribution.3. Regression analysis showed that number of alien plants generally showed a U pattern with an increase of altitudes. Aliens were more distributed at sites with low altitudes (< 2,300 m) and high altitudes (>3,000 m). The result contrasted with distribution pattern of native plants which had the most richness in middle altitude ranges. For the travel distances, alien plants decreased monotonously along distances while native plants did not show any patterns associated with travel distances.4. The results of multiple comparisons demonstrated that diversity indices of alien plants along routes with more frequency tourism activities were obviously higher than less frequency routes. Meanwhile, more alien plants were distributed along motorized, horse-riding and mixed routes, while less aliens were located along hiking routes, which demonstrates that recreational vehicles and pack animals contributes more dispersal of aliens within the park than tourists themselves.Based on above results, we know that certain number of alien plants have established along recreational routes in Laojun Mountain national park. As recreational use increase, the number of alien plants and the areas they occupy associated with tourism activities can also be expected to increase. Thus, effective management measures (e.g. cleaning vehicles and cloths, seasonal or route denial to access, etc) are suggested to Laojun Mountain national park in order to prevent and eliminate possible risks of biological invasions induced by tourism activities.