陆生生境入侵植物空心莲子草群落数量分类与排序

Numerical classification and ordination of invasive plant Alternanthera philoxeroides community in terrestrial habitats

通过在中国大陆21°N^37°N大纬度梯度范围内(10省20市)设置59个野外调查样地,结合双向指示种分析法(TWINSPAN)和除趋势对应分析法(DCA),探讨了陆生生境入侵植物空心莲子草(Alternanthera philoxeroides)群落的物种组成特征及其群丛类型划分。同时,采用除趋势典范对应分析方法(DCCA)对入侵群落物种沿着环境梯度(经度、纬度和海拔)的分布进行二维排序。结果表明:(1)59个样地群落共记录植物170种,隶属于52科134属,空心莲子草的优势地位显著(总重要值为32.390),出现频次较高的伴生植物有莲子草(Alternanthera sessilis)(16/59)、水蓼(Polygonum hydropiper)(13/59)和马唐(Digitaria sanguinalis)(12/59);(2)TWINSPAN分类和DCA排序将陆生空心莲子草群落划分为10类群丛,其中,空心莲子草+马唐群丛的出现频率最高(8/59),马唐为陆生空心莲子草在野外群落中伴生规模最大的本土种,未来可以考虑利用马唐对空心莲子草入侵进行竞争替代;(3)DCCA排序表明,纬度是决定群落物种分布的首要环境因子,TWINSPAN将群落中的30种主要植物(总重要值>0.2)划分为10个种组,各植物种组在DCCA二维排序图上的分布与分类结果基本吻合,空心莲子草与葎草(Humulus scandens)的排序位置最为接近;(4)DCA和DCCA排序均反映出了群丛及物种分布的水分环境梯度,随着纬度上升,空心莲子草入侵群落中的植物逐渐由中生物种过渡为湿生物种。以上结果有助于深入理解外来入侵植物群落在大空间尺度上的数量结构特征、预测群落动态以及制定有效的入侵防治管理措施。

In the field survey,we selected 59 sampling plots along the latitudinal gradient（from 21° N to 37° N,which were belonged to 10 provinces and 20 cities） in terrestrial habitats of China's Mainland,to explore the species structure characteristics and association classification of invasive plant Alternanthera philoxeroides community by using two-way indicator species analysis（TWINSPAN） and de-trended correspondence analysis（DCA）. In addition,weused the de-trended canonical correspondence analysis（DCCA） to operate the ordination of plant species distributions along environmental factors（longitude,latitude and elevation）. The results showed that：（1） 59 plots totally recorded 170 plant species,which were belonged to 52 families and 134 genera,A. philoxeroides had a significant highest dominance（its total importance value was 32. 390）. The co-occurring plants which had higher occurrence frequency were Alternanthera sessilis（16/59）,Polygonum hydropiper（13/59） and Digitaria sanguinalis（12/59）;（2） TWINSPAN and DCA divided the A. philoxeroides community into 10 plant associations,A. philoxeroides ＋ D.sanguinalis association had the highest occurrence frequency（8/59）,D. sanguinalis was the main co-occurring native species in A. philoxeroides invaded community,and it could be considered as an potential replacer for A. philoxeroides through interspecific competition in the future;（3） DCCA ordination indicated that latitude was the crucial environmental factor which determined species＇ distributions,TWINSPAN divided the 30 main plant species（which total importance value was more than 0. 2） into ten clusters,distribution regions of each plant cluster on DCCA twodimensional diagram were all consistent with classifications,the ordination position of Humulus scandens was very close to A. philoxeroides;（4） DCA and DCCA all reflected the water gradient of associations and plant species＇ distributions,with latitude increasing,the plant species in filed A. philoxeroides communities gradually changed from mesophytes to hygrophytes. These findings were helpful for understanding the numerical characteristics and predicting dynamics of invasive plant community,as well as making effective measurements for future biological invasions.