贵州高原退化喀斯特植被恢复过程中土壤微生物数量的变化特征

为了研究退化喀斯特植被恢复过程中土壤的生物学特性，采集贵州花江喀斯特高原生态综合治理示范区内不同恢复阶段（裸地阶段、草本群落阶段、灌木群落阶段和乔木群落阶段）的土壤样品，采用微生物培养法分析了退化喀斯特植被恢复过程中不同层次、不同季节及根际和非根际土壤微生物数量的分布特征。结果表明：退化喀斯特植被恢复过程中土壤中的微生物数量分布存在较大差异，、随着退化喀斯特植被的恢复，土壤细菌、真菌、放线菌的数量及其总数明显上升．表现为齐木群落阶段〉灌木群落阶段〉草本群落阶段〉裸地阶段；土壤剖面上土壤微生物数量均呈明显的垂直分布特征．即随土层深度的增加，呈递减趋势，具体表现为A层〉B层（P〈0．05）；从季节变化上来看，土壤细菌、真菌、放线菌的数量及其总数季节变化明显，夏季达最大（6．16×10^6，1．11×10^5，3．16×10^5及6．59×10^6个·g^-1），冬季最小（3．42×10^6，0．45×10^5，1．75×10^5及3．64×10^6个·g^-1），总体上表现为夏季〉秋季〉春季〉冬季的特点（Jp〈0．05）根际和根外变化明显，表现为根际〉非根际（P〈0．05）。退化喀斯特植被恢复增加了土壤微生物数量，使土壤质量得以提高.

Ecological characteristics of soil microbial amount during succession of degraded karst vegetation on the Guizhou Plateau

In order to study the biological characteristics of soil quality during degraded karst vegetation restoration, soil samples were collected from different restoration stages(bare land stage, herbaceous com-munity stage, shrubby community stage and the arboreal community stage)in the Karst Plateau Ecological Synthesis Control Area in Huajiang of Guizhou. By using microbial incubation methods(with methods of di-lution plate smearing and statistical analysis), the distributions of soil microbial amount in different soil layers as well as the rhizosphere and non-rhizosphere areas, and for different seasons, were studied. The results showed that with restoration of degraded karst vegetation, there was a highly significant increase (P<0. 01)in microbial amount(bacteria, fungi, actinomyces, and total microbes)with the arboreal com-munity stage>shrubby community stage>herbaceous community stage>bare land stage. Soil microbial amount significantly decreased(P<0. 05)in the soil profile with an increase of soil depth with layer A>layer B. Also, for seasonal change, soil microbial amount(in CFU·g~(-1))was highest in summer(6. 16 × 10~6for bacteria, 1. 11 × 10~5 for fungi, 3. 16 × 10~5 for actinomyces, and 6. 59×10~6 for total microbial amount)and lowest in winter(3. 42 × 10~6 for bacteria, 0. 45×10~5 for fungi, 1. 75 × 10~5 for actinomyces. and 3. 64× 10~6 for total microbial amount). Overall, the seasons were summer>autumn>spring>winter. and statis. tical analysis showed significant differences(P<0. 05). Additionally, microbial amount in the rhizosphere was significantly greater(P<0. 05)than the non-rhizosphere. Thus. soil microbial amount increased during vegetation restoration of degraded karst lands, which indicated soil quality gradually improved. Ch, 2 fig. 2 tab. 21 ref. ]