人为践踏对南京紫金山天然次生林土壤渗透性的影响

Effect of human trampling on soil infiltration of natural secondary forest in Zijin Mountain,Nanjing

【目的】探讨不同程度人为践踏对土壤涵养水源功能及土壤渗透性等指标的影响,以期为紫金山国家森林公园的生态旅游管理提供依据。【方法】在南京紫金山国家森林公园内选择两处不同海拔的天然次生林试验区,每个试验区中选取5条不同践踏强度的小径,并选择3处未受人为践踏的区域为对照,测定土壤各物理指标,分析人为践踏对土壤渗透能力的影响。【结果】不同人为践踏强度下土壤容重、总孔隙度、毛管孔隙度以及非毛管孔隙度会发生变化;践踏对低海拔处土壤容重的影响比高海拔处的更加明显。土壤的饱和含水量、毛管持水量以及田间持水量会因人为践踏产生不同程度的降低;土壤的渗透过程、初渗率、稳渗率、平均入渗率以及渗透总量会因人为践踏呈显著降低(P<0.05);研究发现践踏对低海拔处土壤渗透能力的影响比高海拔处的明显。结构方程模型分析发现践踏强度、土壤总孔隙度对土壤渗透能力的影响系数较大。【结论】人为践踏可导致土壤容重变大、土壤紧实度变大、孔隙度降低、土壤的通气性降低、持水能力减弱、土壤的渗透性变差;人为践踏强度越大,土壤渗透能力降低越明显。

【Objective】The effects of human trampling on soil water conservation function and soil permeability were discussed to provide a basis for ecotourism management in Nanjing Zijin National Mountain Forest Park,China.【Method】Two secondary forest experimental areas with different altitudes were selected in the study area,and five trails experiencing different trampling intensities were selected in each experimental area.Three areas without human trampling were used as the control in each experimental area to determine soil physical indices and explore the influence of human trampling on soil permeability.【Result】Soil bulk density,total porosity,capillary porosity,and non-capillary porosity changed under different human trampling intensities;soil bulk density was more impacted by trampling at low altitude than at high altitude.The results showed that the saturated water content,capillary water holding capacity,and field water holding capacity of soil decreased due to human trampling.The infiltration process,initial infiltration rate,steady infiltration rate,average infiltration rate,and total infiltration amount had shown significant decreases due to human trampling(P<0.05).The results showed that the soil permeability at low altitude was obvious affected by trampling compared with high altitude.Structural equation model analysis showed that trampling intensity and soil total porosity had the greatest influence on soil permeability.【Conclusion】Artificial trampling increases soil bulk density and compactness,decreases porosity and soil aeration,and deteriorates the water holding capacity and permeability of soil.The higher the intensity of the human trampling,the greater the decrease in soil permeability.