- Wen, YG; Lei, LQ; Zhu, HG; Liu, H; Qin, L; Ma, ZL; Wang, KL; Zhuang, J; Lan, JC; Long, T; Lu, XM; Deng, Y; Xie, YJ; Wang, JY
- Desertified karst region is a focal and difficult area of vegetation recovery and ecological restoration in southwest China. We investigated changes of the regeneration, succession and community characteristics in karst vegetation after stopping human disturbance, based on a chronosequence in the kart region of Mashan county. Our sampling includes 15 plots, each of 20 m×50 m representing five successional stages (desertified karst land, grassland, scrub, young forest and mature forest). We found that vegetation succession proceeded from desertified karst land to grassland to scrub to young forest, and finally to mature forest. Vegetation cover was significant different among different successional communities at three different layers(P<0.05). The greatest cover of arbor layer was found in mature forests, of shrub layer was in young forests, and of grass layer was in scrub stage, while the maximum number of species, genera and families with importance values (IV) ≥10.00 were found in young forests. Community structures of all layers were remarkably different among successional stages, so were plant density of the tree layer, with the maximum tree density found in young forests. Plant density of the shrub layer in the mature forests was significantly lower than that in young forests and grasslands(P<0.05), and was not significantly different with desertified karst lands and scrubs(P >0.05).Species richness of the communities increased with succession, but the changes were different among all layers in different successional stages. The greatest species richness in the grass layer was found in the grassland and the lowest in the mature forest; the greatest species richness in the shrub layer was found in the young forest and the lowest in the desertified karst land stage; the greatest species richness in the tree layer was found in the young forest and the least in the mature forest. Ecological dominance was not significantly different among grass layers in different successional stages(P >0.05), but significantly different among shrub and arbor layers in different successional stages(P<0.05). The restoration of karst vegetation can be divided into two stages, each with a threshold, i.e. harsh physical environments and deficiency of climax species, respectively. At each stage, the successive direction and speed depended on the presence of different driving and keystone species with different functional characteristics. The later a successional stage was, the more aboundance of climax species, and the more obvious it was that the driving and keystone species were those of advanced, large-sized and long-lived.
- January 1, 2013
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