CAS Workshop on Ecosystem Succession Theory and Practice of Ecological Restoration

鹤山退化生态系统恢复过程中土壤微生物特性的研究 

周丽霞  蚁伟民  易志刚  丁明懋

（中国科学院华南植物研究所生态中心，广州 510650） 

摘要：为进一步了解退化生态系统在恢复过程中土壤微生物特性的变化，我们于2002年7月对鹤山丘陵荒坡种植的人工植被中的针叶林、红荷木林、豆科植物混交林、马占相思林、果园、鱼塘以及龙口村边次生林7个样地进行了土壤微生物区系组成分析；对马占相思林、红荷木林、果园和针叶林4个样地进行了土壤微生物生物量的测定。结果表明：

1.         鹤山不同类型的人工植被下土壤微生物主要类群的数量与组成是细菌>放线菌>真菌，与1988年的研究结果相一致，但各试验林地土壤中细菌的数量与比率有较大幅度的提高（从32.1 ~ 79.9%提高到71.4 ~ 89.3%), 真菌和放线菌的数量与比率有所下降（比率分别从6.9 ~ 28.6%和6.8 ~ 39.3%下降到1.1 ~ 9.5%和1.8 ~ 22.7%）。 人工植被中土壤微生物生物量 (mg C_mic•100g^-1 dry soil) 为29.68 ~ 57.11, 由高到低依次顺序是马占相思林（57.11）> 果园 (47.79）> 红荷木林 (42.55 ) > 针叶林 (29.68 )，与土壤有机质的大小排列顺序相吻合（土壤有机质依次是2.78%、2.31%、2.17%、2.05%)，说明土壤微生物生物量的大小与土壤有机碳含量的多少密切相关。由于细菌对土壤水肥条件较敏感，细菌比率的增长意味着土壤肥力的改善；土壤微生物量的增加，又反映了土壤有机质的积累和增加。综合上述两点可见，鹤山人工植被的土壤质地比植被恢复前或植被恢复早期已有了较大幅度的改善与提高，退化土地正处于恢复之中，土壤质地向着有利于植被生长与持续发展生产的良性循环方向发展。

2.         马占相思人工植被在微生物总数、细菌数量与比率方面均较10几年前有了较大幅度增加，并且高于其它人工植被，接近村边次生林；同时马占相思人工植被土壤微生物量也高于其它人工植被；所以马占相思林地土壤微生物的恢复速率快过其它人工植被。表明豆科树种作为丘陵荒坡植被恢复的先锋树种，对退化土地的地力恢复有积极意义。

3.         鹤山人工植被中的土壤微生物碳与土壤有机碳之比（C_mic ：C_org）在24.96 ~ 35.67 mg C_mic• g^-1 C_org 的范围内， 比鼎湖山报道的400年生自然林的C_mic ：C_org（19.5 mg C_mic• g^-1 C_org）要高。由于该自然林被认为是鼎湖山较成熟的顶极群落，林下土壤熟化程度较高，可以认为其土壤碳循环已经达到了平衡状态，故土壤微生物碳与土壤有机碳之比（C_mic ：C_org）高于上述自然林的，被认为是碳的积累阶段，反之则是碳的流失阶段。由此可见鹤山人工植被下的土壤正处于碳素的积累过程之中。与10年前的研究结果相比，马占相思林（由27.70到35.41 mg C_mic ：g^-1 C_org  ）表现出更强的碳积累。

关键词：退化生态系统恢复；土壤微生物特性 

Soil microbial characteristics in the rehabilitation process of degraded ecosystems in Heshan area

 Zhou Lixia  Yi Weimin  Yi Zhigang  Ding Mingmao

 (South China Institute of Botany, Chinese Academy of Sciences, Guangzhou 510650, China)

Abstract: The number and composition of soil microbes in several ecosystems of Coniferous forest, Schima wallichii forest , Mixed forest of legumes , Acacia mangium forest, Orchard , Fish pond and Secondary forest were investigated , and the soil microbial biomass for Coniferous forest, Schima wallichii forest, Acacia mangium forest and Orchard were also measured in Heshan area, on July 2002 . The result were given as follow:

1.         The number of soil bacteria , fungi and actinomycetes from more to less were in order : Bacteria > Fungi >Actinomycetes , it is similar to the results investigated in 1988. However, the percentage of bacteria were increased quickly in all vegetations (from 32.1 ~ 79.9% in 1988 increased to 71.4 ~ 89.3% until now), and the percentage for fungi and actinomycetes were decreased (from 6.9 ~ 28.6% and 6.8 ~ 39.3% to 1.1 ~ 9.5% and 1.8 ~ 22.7% , respectively). The soil microbial biomass (mg C_mic•100g^-1D.S) in the studied plots from higher to lower was in order : Acacia mangium forest (57.11) > Orchard (47.79 ) > Schima wallichii forest (42.55) > Coniferous forest (29.68 ) , the similar order was found in the contents of orginic matter for the soils in the corresponding plots (2.78% > 2.31% > 2.17% > 2.05%）,  it’s showed that the increase of bacteria percentage means the imporvement of soil water and fertility due to the bacteria was sensitive to the fertility and water of soil , and higher soil microbial biomass means the accumulation and increase of soil organic matter, both of these implied that the soil property have been recovering after afforestation.

2.         The ecosystem of Acacia mangium forest with higher bacteria percentage , microbial biomass  and soil organic matter compared with other man-made ecosystems appeared to be fast rehabilitation of the ecosystem , therefore , it could be consider that leguminous plants as the pioneer plants are suitable for the rehabilitation of the degraded ecosystem in this area .

3.         The ratios of soil microbial C to soil organic C (C_mic ：C_org ) were ranged from 24.96 ~ 35.67 mg C_mic• g^-1 C_org  in Heshan man-made forest ecosystems , which was higher than that in the natural forest ecosystem with 400a in Dinghushan（19.5 mg C_mic• g^-1 C_org）. In general condition , it was believed that the natural forest ecosysten with 400a in Dinghushan was the mature forest ecosystem with soil carbon balance .  For this reason , it was considered that the forest ecosystem with higher ratio of C_mic ：C_org  compared with the natural forest ecosystem in Dinghushan in this area was at the stage of soil carbon accumulation , on the contrary , the forest ecosystem was at the stage of soil carbon loss . Therefore , all of the man-made forest ecosystems in Heshan were in the stage of soil carbon accumulation owing to their ratios of C_mic ：C_org  was higher compared with the natural forest ecosystem in Dinghushan . In contrast with the result (27.70 mg C_mic ：g^-1 C_org ) investigated in 1988 , the Acacia mangium forest ecosystem with 35.41 mg C_mic ：g^-1 C_org  in 2002 appeared in soil carbon accumulation strongly .

Key words: rehabilitation of degraded ecosystems; soil microbial characteristics

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