Abstract: Earthquake and its secondary disasters lead to ecological degradation. Vegetation restoration and regenera tion of the earthquake landslide bring the opportunity for the co-evolution of biology and environment. For better understanding the regeneration characteristics of secondary vegetation in the landslide mass, we investigated species composition and niche characteristics of major species of secondary plant communities in the landslide mass, which was seriously damaged during the Wenchuan earthquake and had been recovered naturally for 11 years. The results showed that a total of 116 species belonging to 93 genera and 56 families were recorded, with 78 herbaceous species and 38 woody species. In addition, plant communities were mainly secondary herbaceous ones, and the species were mainly composed of pioneer species of Asteraceae, Poaceae and Rosaceae, such as Fragaria ananassa and Rubus setchuenensis. Beyond those species, Leucobryum glaucum was also abundant. Niche characteristics of dominant species of herbaceous and woody plants with the top 20 of importance value were analyzed. It was found that: (1) the niche breadth of the main species was positively correlated with the importance values and species distribution frequency (P<0.05), whereas there was a significantly negative correlation between the variation coefficient of the importance value and the niche breadth concerning the main secondary woody species (P<0.01); and (2) there was a significantly positive correlation between the niche breadth and niche overlap of main woody plants in the community (P<0.01). Nevertheless, there was no positive correlation between niche breadth and niche overlap of main herbaceous species. Such a result indicates that not all plant species conform to the law that niche overlap would increase with increasing niche breadth; (3) there was a significantly positive correlation between niche similarity and niche overlap (P<0.01). The average niche overlap values of herbaceous communities and woody communities were 0.12 and 0.13 respectively, indicating that the species of secondary plant community had obvious niche differentiation and large difference in resource utilization. The interspecific relationship of secondary plant communities in earthquake landslide was relatively harmonious to ensure long-term coexistence and adaptation of species.

Key words: earthquake landslide mass, secondary plant community, niche breadth, niche overlap.