The sample plot survey and analysis methods were applied to investigate four typical grass-forest systems in lake buffer zone of Zhushan Bay of Lake Taihu, including wetland grass-forest system, poplar protection forest, nearby tributary grass-forest system and taxodiumascendens protection forest.The soil nutrient contents of organic matter, nitrogen and phosphorus, the plant growth situation including biodiversity, canopy density and grass coverage, the bacterial population and soil physical properties were studied in detail.The results showed that the organic matter contents of surface soil was between 15.1 g∕kg and 40.3 g∕kg (level 1 to 4), overall at rich level;the total nitrogen content of soil was between 0.76 g∕kg and 1.13 g∕kg (level 3 to 4), overall at medium or slightly low level;while the total phosphate content was between 0.09 g∕kg and 0.17 g∕kg, all at level 6 (extremely low level). Compared with the soils in China and other countries, the organic matter, total nitrogen, ammonium nitrogen and nitrate nitrogen contents in Zhushan Bay were totally at a medium level, while the total phosphate content was at a low grade.The soil nutrient index calculated from bacterial population indicated that the nutrient levels of the four grass-forest systems were very low, only between 0.003 and 0.014.The evaluation on plant growth situation showed that the grass-forest system was relatively good, but all the four grass-forest systems had very low biodiversity. Therefore, it is difficult to recommend a good grass-forest system example only from the present four systems.%采用样地调查及取样分析方法对太湖竺山湾缓冲带湿地型草林、杨树防护林型草林、支浜旁草林和池杉防护林型草林4种草林系统的碳、氮、磷等土壤养分浓度，生物多样性、林木郁闭度、草本覆盖度等草林生长状态，土壤微生物含量，土壤物理性状等进行了调查研究。结果表明，调查区域草林系统的土壤有机质浓度为15．1～40．3 g∕kg （1～4级），总体上为丰富水平；全氮浓度为0．76～1．13 g∕kg（3～4级），总体为中等偏低水平；全磷浓度为0．09～0．17 g∕kg（6级），均为极缺乏水平。与我国其他地区相比，太湖竺山湾缓冲带林下土壤的养分浓度除全磷处于较低水平外，有机质、全氮、铵态氮、硝态氮等均处于中等水平。根据微生物数量计算的土壤营养指数表明，4种草林系统的营养级别都极低，土壤营养指数仅0．003～0．014。草林生长状态评估结果表明，杨树防护林型样地相对较好，但普遍存在生物多样性低的弱点，能否作为生态效益高的草林系统效仿样本林，还值得进一步研究。
展开▼
