晋西黄土区不同密度刺槐林土壤入渗特征及其影响因素

为研究林分密度对土壤入渗性能的影响,以晋西黄土区5种密度(1 075,1 300,1 575,1 800,2 150株/hm~2)刺槐(Robinia pseudoacacia Linn.)林为研究对象,采用双环入渗法测定其土壤入渗过程,并对入渗特征指标与土壤理化性质的相关性进行分析。结果表明:(1)不同密度刺槐林土壤入渗过程的变化规律一致,均经过瞬间入渗(0～5 min)、缓慢入渗(5～40 min)和稳定入渗(40 min后)阶段。(2)土壤初始入渗速率、稳定入渗速率、平均入渗速率和累积入渗量在不同林分密度下差异显著(P0.05),不同密度刺槐林土壤入渗能力表现为1 075～1 800株/hm~2,随林分密度增大,土壤入渗能力增强,在密度1 800株/hm~2后有减弱的趋势。故从林地土壤入渗能力角度,建议今后研究区刺槐林的经营密度以1 800株/hm~2为宜。(3)采用Kostiakov模型、Horton模型、Philip模型和通用经验模型对不同密度刺槐林的土壤入渗过程进行模拟,从决定系数R~2来看,通用经验模型的R~2最大(0.990),故拟合效果最好,可作为晋西黄土区刺槐林土壤入渗过程的预测模型。(4)土壤入渗与土壤理化性质密切相关,不同密度刺槐林的土壤入渗性能与土壤容重呈极显著负相关(P0.01),与有机质和0.25 mm水稳性团聚体含量呈极显著正相关(P0.01),与孔隙状况和质量含水率也有一定正相关性。

Soil Infiltration Characteristics and Influencing Factors of Robinia pseudoacacia Linn. with Different Densities in Loess Region of Western Shanxi Province

In order to study the influence of stand density on soil infiltration performance, five kinds of Robinia pseudoacacia Linn. stands (1 075, 1 300, 1 575, 1 800, 2 150 trees/hm²) in Loess region of Western Shanxi Province were selected as the research object. The soil infiltration process was determined by double-loop infiltration method, and the correlation of infiltration characteristic index and soil physicochemical properties were also analyzed. The results showed that: (1) The process of soil infiltration in Robinia pseudoacacia Linn. with different densities was the same, all of them went through the stages of transient infiltration, gradual infiltration, and stable infiltration. (2) There were significant differences in initial infiltration rates, stable infiltration rates, average infiltration rates and cumulative infiltration amount under different stand densities (P<0.05). With the increase of stand densities (1 075~1 800 trees/hm²), soil infiltration capability increased. After the stand density of Robinia pseudoacacia Linn. was more than 1 800 trees/hm², there was a trend of weakening in soil infiltration. Therefore, it was suggested that the management density of Robinia pseudoacacia Linn. in Loess region of Western Shanxi Province should be 1 800 trees/hm². (3) The soil infiltration process of Robinia pseudoacacia Linn. with different densities was simulated by Kostiakov model, Horton model, Philip model and Universal Empirical model. In terms of R², the Universal Empirical model had the largest R²(0.990), and could be used as a predictive model for the soil infiltration process of Robinia pseudoacacia Linn. in Loess region of Western Shanxi Province. (4) Soil infiltration capability was negatively correlated with soil bulk density (P<0.01), positively correlated with organic matter and > 0.25 mm water-stable aggregate (P<0.01), and positively correlated with pore condition and water content.