Soil Microbial Characteristics in Rehabilitation Process of Degraded Ecosystems in Heshan

Abstract:

The amount and composition of soil microbes including bacteria, fungi and actinomycetes were investigated in July 2002 in Heshan Hillyland Interdisciplinary Station where afforestation was undertaken on waste downland since 1983. Soil samples were collected at 0-15 cm depth from plots of seven sites, i.e. I, Pinus massoniana forest (planted in 1983); II, Schima wallichii forest (1987)； III, Mixed forest of legumes (planted during 1983-1987)； IV, Acacia mangium forest (1983)； V, Orchard (1985)； VI Fish pond sludge(fish pond was established in 1985)；and VII，Secondary forest near village．Microbial am ount Was highest in site VII(6.323×10⁶g^-1 dry soil)，folowed byⅣ，V，Ⅱ,III,VI,and lowest inI(1.424xl06 g dry sold．111e number ofsoil microbes was in the order：bacteria > actinomycetes > fungi，which Was similar to the results obtained in l988．However，the percentage ofbacteria Was increased rapidly in all sites(from 32.1％-79.9％in 1988 to 71.4％-87.7％now)，and the percentage of fungi and actinomycetes were decreased (from 6.8％-28.6％and 6.8％-39.3％to 1.1％-9.6％and 9.2％-22.7％，respectively)．Soil microbial biomass(mg C_mic (100g)^-1 dry soil)in sites was in the order：IV(57.11)> V(47.79)>II(42.55)>I(29.68)，which had a similar sequence for soil organic carbon in the corresponding sites．The increase of total amount of microbes，especially ofthe number and percentage of bactefia suggests that the soil properties under artificial forests were improved， and most obvious result Was foun d in soil un der aforestation by Acacia mangium．