地形因素对外来入侵种紫茎泽兰的影响

THE INFLUENCE OF TOPOGRAPHICAL FACTORS ON THE INVASION OF THE ALIEN SPECIES, EUPATORIUM ADENOPHORUM

在紫茎泽兰 (Eupatoriumadenophorum)的分布区内设置 171块临时样地 ,研究它的盖度和多度与经纬度、海拔、坡向、坡度、风向坡等地形因素的关系。结果表明 ,紫茎泽兰入侵最严重地区位于 10 2°E左右 ,随着纬度增加入侵能力逐渐下降 ,但不显著 (p>0 .0 5 ) ;紫茎泽兰在中国的分布以云贵高原 ,尤其是云南高原为主体 ,通过云贵高原与原产地墨西哥、哥斯达黎加的气候条件对比 ,推断紫茎泽兰将来在中国的分布区主体还将局限在云贵高原 ,但不排除在某些局域气候条件下 ,形成斑块的可能 ;该次调查的海拔范围为 75m～ 2 330m ,以 2 0 0m为一个海拔梯度 ,多项式回归分析显示 :紫茎泽兰的盖度与多度随着海拔升高而增加 (p <0 .0 5 ) ,但在 2 0 0 0m左右已趋平缓 ,表明紫茎泽兰适宜生长在海拔 2 0 0 0m左右 ;ANOVA的结果显示 :坡向对紫茎泽兰的入侵影响显著 (p <0 .0 5 ) ,通过多重比较发现 ,北坡和南坡的盖度比东坡大 (p <0 .0 5 ) ;北坡的多度比东坡大 (p <0 .0 5 ) ,说明东坡不易被紫茎泽兰入侵 ,而北坡和南坡紫茎泽兰的盖度和多度差异并不显著 (p>0 .0 5 ) ,说明温度与湿度可能不是造成不同坡向紫茎泽兰入侵差异的主导因素 ;坡度对紫茎泽兰入侵的影响并不显著 (p >0 .0 5 ) ;

To study the distribution of Eupatorium adenophorum in China and the relationship between its invasion and topographical factors, including elevation, aspect, slope and wind slope, 171 plots were established in 12 vegetation provinces within this species range. The results indicated that the invasion of E. adenophorum mostly occured in regions near 102° E and declined with latitude, but not significant (p > 0.05). The range of E. adenophorum in China was mainly on the Yungui Plateau, particularly the Yunnan Plateau. Based on climatic comparisons between the Yungui Plateau and this species native range in Mexico and Costa Rica, we concluded that the future range of E. adenophorum in China would be confined largely to the Yungui Plateau, although patches are likely to occur in other regions with suitable climatic conditions. The elevation range of this species was from 75 m to 2 330 m in our investigation. Using polynomial regressions, we concluded that the abundance and coverage of E. adenophorum increased with elevation (p < 0.05), but at about 2 000 m elevation, the line became horizontal, suggesting that E. adenophorum preferred elevations of about 2 000 m. An ANOVA analysis showed that the influence of aspect on the coverage of E. adenophorum was significant. Multiple comparison tests suggested that the coverage of E. adenophorum on north and south facing slopes was greater than that on east facing slopes, indicating a strong resistance of east facing slopes to the invasion of E. adenophorum. The difference between population coverage and abundance on north and south facing slopes was not significant (p>0.05), indicating that temperature and moisture were not the dominant factors influencing the invasion of E. adenophorum on different aspects. The influence of slope on the invasion of E. adenophorum was not significant (p>0.05). The results of the ANOVA analysis indicated that the influence of wind slope on the coverage of E. adenophorum was not significant (p>0.05) but significantly affected the abundance of E. adenophorum (p<0.05) with the abundance of E. adenophorum greater on the leeward than on the lateral side.