【目的】探究踩踏干扰下紫金山国家城市森林公园土壤质量变化特征,分析季节变化对同一踩踏干扰条件下土壤质量的影响。【方法】以南京紫金山国家城市森林公园土壤为研究对象,随机选择8条宽度为3 m的游人道路,将7 m×1 m的土壤采集样带垂直设置在每条游人步道上,每条土壤采集样带上设置3个土壤取样点,分别作为活动区、缓冲区、背景区。测定游人道路在不同踩踏干扰强度下土壤理化性质和土壤酶活性的季节变化。采用因子分析法计算主成分的方差贡献率,并对各指标在各主成分线性组合中的系数进行加权平均,探究土壤质量变化规律。【结果】在背景区、缓冲区和活动区,土壤容重以春、秋季较高,夏、冬季较低,夏、冬季土壤最大持水量和孔隙度高于春、秋季;土壤pH以夏、冬季高于春、秋季;春季土壤有机质含量显著低于夏、秋、冬季,土壤速效磷养分含量以夏季最高、春季最低;夏季土壤酶活性高于春、秋、冬3季。在背景区,春季土壤质量低于夏、秋、冬3季;在不同踩踏干扰程度下,夏、冬季土壤质量均高于春、秋季;随着踩踏干扰强度增强,土壤容重和pH在4个季节均呈上升趋势,土壤最大持水量、孔隙度、生化指标和土壤酶活性在4个季节均呈下降趋势。结构平衡方程模型(SEM)分析显示,土壤理化指标和土壤酶活性与土壤质量存在显著相关性。【结论】土壤全氮含量、速效磷含量、最大持水量和蔗糖酶活性对不同季节和踩踏干扰强度下土壤质量变化的贡献度较大,可以作为紫金山国家城市森林公园土壤综合质量评价指标;季节变化对同一踩踏干扰强度的土壤理化性质和土壤酶活性影响显著。

【Objective】 This research aims to explore the characteristics of soil quality change in Zijin Mountain National Urban Forest Park under trampling disturbance and study the influence of seasonal changes on soil quality under the same trampling disturbance conditions. 【Method】This study took Nanjing Zijin Mountain National Urban Forest Park as the research object. Eight tourist roads with a width of 3 m were randomly selected; a 7 m × 1 m soil collection sample strip was set vertically on each tourist trail, and soil was collected from each strip. Three 1 m × 1 m soil sampling points were set up on the transect. The first, second and third sampling points were respectively 1 m, 3 m and 7 m away from the center of the road as the active area, buffer zone and background area, respectively. The soil was collected over four seasons to determine the seasonal changes in soil physical and chemical properties and soil enzymes under different trampling disturbance intensities on the tourist roads. A factor analysis method was used to calculate the variance contribution rates of the principal components, and the coefficients of each index in the linear combination of the principal components were weighted and averaged to determine the weight and law of soil quality changes. 【Result】 In the background area, buffer zone and active area, the bulk density was higher in spring and autumn and lower in summer and winter. The maximum moisture content and porosity of the soil in summer and winter were higher than those in spring and autumn. The pH were higher in summer and winter, and lower in spring and autumn. The organic matter content in spring was significantly lower than that in summer, autumn and winter, and the content of available phosphorus was the highest in summer and lowest in spring. Soil enzyme activity in summer was higher than that in spring, autumn and winter. In the background area, the soil quality in spring was lower than that in summer, autumn and winter. Under different degrees of trampling disturbance, the soil quality in summer and winter was higher than that in spring and autumn. With increasing intensity of trampling disturbance, soil bulk density and pH showed an upward trend in the four seasons. However, maximum moisture content, capillary porosity, biochemical indicators and enzyme activity all showed a downward trend in the four seasons. Structural equilibrium equation model (SEM) analysis showed that soil physical and chemical characteristics and soil enzyme activity were significantly correlated with soil quality. 【Conclusion】 The study showed that soil total nitrogen content, available phosphorus content, maximum moisture content, and enzyme activity are more weighted; that is, they make a greater contribution to changes in soil quality under different seasons and intensities of trampling and can be used as the soil comprehensive quality evaluation index of Zijin Mountain National Urban Forest Park. Seasonal changes have significant effects on soil physical and chemical properties and soil enzymes with the same intensity of trampling disturbance.