三峡河谷苏门白酒草入侵群落特征及种间联结研究

Investigation into Community Characteristics and Interspecific Association of Erigeron sumatrensis in the Three Gorges Valley

苏门白酒草(Erigeron sumatrensis)是一种外来恶性杂草,其入侵严重威胁入侵地农业生物多样性和生态系统功能。为有效观测与评估不同海拔苏门白酒草入侵的危害程度,以三峡河谷地带的苏门白酒草入侵群落为研究对象,在三峡河谷地带设置180个1 m×1 m样方,采用χ^(2)统计量、方差比率法(VR)、联结系数(AC)、匹配系数Ochiai和Dice、Gordon M群落稳定性测度方法分别对其种间联结关系与群落稳定性进行研究。结果表明:(1)苏门白酒草入侵群落中共有149种伴生植物,从低海拔的56种到高海拔的97种,海拔高度上升显著增加了入侵群落物种多样性,物种的重要值普遍增大,且地上生物量增加。(2)低海拔和高海拔群落中苏门白酒草的优势度和生态位宽度最大,中海拔群落中鹅肠菜(Stellaria aquatica)的优势度和生态位宽度最大。与低海拔相比,中海拔和高海拔群落中苏门白酒草的优势度分别增长1.09%和8.32%。(3)χ^(2)检验和联结系数表明,低海拔入侵群落种间呈不显著负联结,中海拔入侵群落种间呈显著正联结,高海拔入侵群落种间呈显著负联结。入侵群落总体呈不显著负联结,群落内种间联结松散,独立分布性较强。群落稳定性结果显示,低海拔和中海拔群落的交点坐标分别为(39.85,59.98)、(35.79,63.91),交点坐标距稳定点坐标(20,80)有一定距离,表明苏门白酒草入侵群落处于非稳定状态。高海拔群落的稳定性比值为(26.82,73.28),靠近稳定点坐标,说明群落稳定性较高。

Erigeron sumatrensis is an exotic noxious weed,which is a serious threat to agricultural biodiversity and ecosystem function.In order to effectively observe and evaluate the invasion degree of Erigeron sumatrensis at different elevations,180 quadrats were set up in the Three Gorges River Valley.The interspecific association and community stability were studied by test statistics,variance ratio,association coefficient,matching coefficient and Gordon M community stability measurement method.The results indicate that:(1)A total of 149 species of parasitic plants were found in the invasive community,ranging from 56 species at low-altitude to 97 species at high-altitude.The changes of altitude significantly increased the species diversity of invasive communities,the important values of species were generally higher,and the aboveground biomass increased.(2)The dominant degree and niche width were the largest in the low and high-altitude communities,and Stellaria aquatica was the largest in the intermediate-altitude communities.Compared with the low-altitude,the dominance of the intermediate-altitude and high-altitude communities increased by 1.09%and 8.32%,respectively.(3)Theχ^(2)test and association coefficient show that there was no significant negative association between the species of low-altitude invasive communities,while significant positive association existed between the species of intermediate-altitude invasive communities,and significant negative association existed between the species of high-altitude invasive communities.The invasive community generally showed no significant negative association,and the interspecies association was loose and the independent distribution was strong.The data of community stability show that the intersection coordinates of low altitude and middle altitude communities were(39.85,59.98)and(35.79,63.91),respectively,and the distance between the two intersection coordinates was(20,80),indicating that the invasion community of Erigeron sumatrensis was in an unstable state.The stability ratio of high-altitude communities is(26.82,72.28),which is close to the stable point coordinates and shows high community stability.