Resumen de Effect of Alnus nepalensis cultivation on soil biological and physicochemical properties during restoration near a phosphate smelter in Kunyang, Yunnan Province, SW China
L He, X Fang, Guixing Meng, G. Li, J. Shao, Y Chai, J. Kong
In this study, soil physicochemical properties, microbial community structure and nematode assemblages were investigated to assess the soil qualities of an in situ phosphate mine after up to 10 years of revegetation with the nurse plant Alnus nepalensis. Our results showed that A. nepalensis cultivation significantly decreased the total P concentration, suggesting the high remediation potential. Moreover, A. nepalensis improved the levels of soil-available N and K and promoted the growth of microorganisms, as suggested by the 1.45- and even 3.26 fold increase in microbial carbon (MBC) and nitrogen (MBN), respectively, after 10 years of remediation. Soil enzyme activities relating to C (β-glucosidase), N (urease) and P (acid phosphatase) were also stimulated. The sum of the indicator phospholipid fatty acids (PLFAs) and the Gram-positive and -negative bacteria also increased significantly after restoration. The nematode density increased gradually from zero in untreated soils to 2.3 g-1 of soil after 10 years of restoration, at which time the highest percentage of plant parasites was observed. Cluster analysis produced three clusters: cultivation for 0 and 1 years in cluster 1; 2, 3 and 4 years in cluster 2; and 5 and 10 years in cluster 3. These results showed that both the nutrient pools and the stability of the soil ecosystems in the revegetated soils were gradually reestablished and that the enzyme activities (β-glucosidase and urease), the microbial community (sum of PLFAs, G+: G-) and the nematode assemblage (density and plant parasite percentage) might be used as valid bioindicators for soil heath after contamination remediation.
