Soil Nitrate Distribution of Bamboo Forest Ecosystems in the Taihu Lake Region: A Case Study of Anji County in Zhejiang Province
太湖地区竹林生态系统土壤硝态氮的分布特征——以浙江省安吉县为例

To examine the role of the bamboo forest in non-point source pollution control in the Taihu lake region, the soil profile nitrate concentration of 5 Phyllostachys pubescens plots and 5 Phyllostachys iridescins plots along the Xitiaoxi River from the upstream to the downstream were measured through July to August in 2009. The relationship between vegetation type and topographic factors and nitrate was analyzed. Results show that 1) soil nitrate concentration decreased with increasing soil depth. 2) In Phyllostachys pubescens plots, the nitrate concentration at a 0-30 cm depth was higher than Phyllostachys iridescins plots; however, the soil nitrate at a 30-50 cm soil depth was higher on Phyllostachys iridescins plots than Phyllostachys pubescens plots. There was no significant differences between these two vegetation plots. 3) Plots having understory vegetation types of grass and shrub had a higher nitrate concentration than understory vegetation type of grass. The differences were marked at a 30-50 cm soil depth. 4) The soil nitrate concentration at a 0-10 cm soil depth in plots whose vegetation height was higher than 5 m was significantly higher than plots whose vegetation height was lower than 5 m. 5) The nitrate concentration of bamboo forest soil decreased first and then increased with increasing elevation. The nitrate concentration at a 0-10cm soil depth above 200 m altitude was higher than those below 200 m altitude. The nitrate concentration at a 10-30 cm soil depth had a similar content between different elevations; however, the nitrate concentration at a 30-50 cm soil depth was higher at lower altitudes and lower at higher altitudes. 6) The soil nitrate concentration at a 0-30 cm depth was higher for steep slopes and lower for gentle slopes. The soil nitrate concentration at a 30-50 cm depth for gentle slopes was higher than steep slopes. In summary, the soil nitrate of different soil depths was found to be closely related to vegetation type and topographic features. Soil water content and hydraulic redistribution which are significantly affected by vegetation, coverage, litter, and topographic factors play an important role in migration and accumulation processes of soil nitrate.