Biodiv Sci ›› 2014, Vol. 22 ›› Issue (2): 157-166.DOI: 10.3724/SP.J.1003.2014.10155

• Orginal Article • Previous Articles     Next Articles

Numerical classification of associations in a northern tropical karst seasonal rain forest and the relationships of these associations with environmental factors

Fuzhao Huang1,2, Bin Wang1,2, Tao Ding1,2, Wusheng Xiang1,2, Xiankun Li1,2,*(), Aiping Zhou1,2   

  1. 1 Guangxi Institute of Botany, Chinese Academy of Sciences, Guilin, Guangxi 541006
    2 Guangxi Youyiguan Forest Ecosystem Research Station, Pingxiang, Guangxi 532600
  • Received:2013-07-08 Accepted:2013-10-28 Online:2014-03-20 Published:2014-04-03
  • Contact: Li Xiankun

Abstract:

The associations in a northern tropical karst seasonal rainforest plot in Nonggang National Nature Reserve were classified using the multivariate regression tree method in conjunction with the relative elevation, slope, aspect, convexity, and the importance value of species. The results showed that the relative elevation and aspect were critical for the spatial distribution of species. The forest community of the Nonggang plot was divided into eight associations. They were as follows: (A) Ardisia thyrsifloraSterculia monospermaSaraca dives association, distributed primarily at the edge of valley bottoms with high humidity and soil moisture; (B) Ficus hispidaSterculia monospermaCaryota obtusa association, distributed primarily at the valley bottom where seasonal flooding occurs and the soil moisture and humidity are high; (C) Catunaregam spinosaVitex kwangsiensisExcentrodendron tonkinense association, distributed primarily on south-facing slopes at lower elevations with slight drought and greater sunlight; (D) Clerodendrum wallichiiSterculia monospermaCychidendron guangxiensis association, distributed primarily on shaded slopes at lower elevations with moderate soil moisture and less sunlight; (E) Aglaia odorataCleistanthus sumatranusExcentrodendron tonkinense association, distributed primarily on upper and middle half-shaded slopes with slight drought; (F) Walsura robustaCleistanthus sumatranusExcentrodendron tonkinense association, distributed primarily on steep half-sunny slopes with slight drought; (G) Chionanthus ramiflorusVitex kwangsiensisExcentrodendron tonkinense association, distributed mainly on passes with a gentle slope, moderate soil moisture, and less sunlight; (H) Clausena dunnianaBoniodendron miniusExcentrodendron tonkinense association, distributed mainly at the top of the mountain and in the surrounding areas, where the longest sunlight periods and the greatest extent of bare rock are accompanied by dry air and a substantial shortage of soil water. According to an analysis of the species components, the changes in species composition were associated with different topographical environmental factors. The spatial distribution of the vegetation was continuous, and there were no obvious boundaries between different associations. These results highlighted the importance of environmental factors as determinants of the distribution of species and the composition of associations in the north tropical karst seasonal rainforest.

Key words: MRT, topographic factor, karst seasonal rainforests, vegetation classification