In China, at the mention of “Karst”, most people may think of the beautiful Karst landscape, suah as the Elephant Trunk Hill in Guilin. But for some people in Guangxi Zhuang Autonomous Region, Karst is just the synonym of poor. The trouble of drinking water, the poor vegetation cover, the serious soil erosion, the intensive anthropogenic disturbance and some other problems have been torturing the local people.
Thus, the ecological restoration and reconstruction in Karst region have always been chanlleges faced by both scentists and the local government.
In previous studies, scientists have found that karst ecosystems are very fragile, due to their soils are usually thin, coarse, very erosive and degenerative. Meanwhile, the Karst soils, covering about 0.55 million km² in the southwest China, were subjected to the intensive anthropogenic disturbances, such as cultivation, deforestation, grazing and burning. Soil microbial community plays an essential role in the recovery of ecosystems, because microorganisms mediate many essential processes and functions of soil, and are suggested to indicate the health, sustainability and stability of ecosystems. So it is very important and meaningful to find a breakthrough based on these microbial functions.
Recently, Dr. Chen Xiangbi in Institute of Subtropical Agriculture（ISA） and her colleagues investigated the effects of cultivation on the composition and diversity of soil bacterial communities in representative Karst ecosystems including a cropland, a naturally revegetated land with former cultivation disturbance and a control forest without human disturbance (a primary forest) based on Restriction Fragment Length Polymorphism (RFLP) and 16S rDNA sequencing.
In their study, compared to the primeval forest, the proportions of the dominant soil bacterial phyla were remarkably changed with cultivation, and the Shannon-Wiener diversity indices and the physicochemical parameters significantly declined in the cropland and the revegetated land with no significant different between the latter two lands. Although the whole soil bacterial community was relatively stable after long-term cultivation disturbance, the subphyla of Proteobacteria, especially for Rhizobiales belonged to α-Proteobacteria, had some positive responses to the 20 years of vegetation recovery. The results suggested that priority should be given to conserve the primeval forest, and inoculation of N₂-fixing microorganisms (Rhizobiales) with indigenous N₂-fixing plants may be more effective to restore the Karst ecosystems after cultivation.
What worthy of mention is that this study provides the first evidence that the composition and diversity of soil bacterial communities has a complex response to cultivation disturbance in Karst ecosystems. This research has given an advice to restore the disturbed Karst ecosystems in microbial perspective.
This study was jointly supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (KSCX2-YW-436 and KZCX2-XB2-08-01), Strategic Priority Research Program of the Chinese Academy of Sciences (XDA05070403) and the National Natural Science Foundation of China (40671104 and 30970538).
The main findings of this study entitled “Soil bacterial community composition and diversity respond to cultivation in Karst ecosystems” have published in January on World Journal of Microbiology and Biotechnology (DOI: 10.1007/s11274-011-0809-0).