黄河三角洲贝壳堤不同植被类型的土壤水分物理特征及蓄水潜能评价

Assessment of Soil Potential Water Storage Ability of Different Vegetation Types at Shell Ridge Island in Yellow River Delta

贝壳堤生态系统具有典型性和脆弱性,土壤蓄水能力决定着贝壳堤系统的稳定性和植被生产力的高低.为阐明贝壳堤不同植被类型土壤蓄持水分能力及其影响因素,测定分析了贝壳砂土壤的基本物理参数、渗透性及土壤水分的温度响应特性,采用模糊数学隶属函数法评价了不同植被类型的土壤蓄水潜能.结果表明:酸枣林、杠柳林和草地能有效改善土壤通透性,土壤总孔隙度分别比裸地增加27.0%、19.3%和10.8%.在30℃和50℃恒温下,不同植被类型的土壤含水量随烘干时间的延长可分为土壤水分瞬变、渐变和平稳3个阶段.两种温度下,土壤饱和含水量、土壤达到恒重时间和失水率均表现为酸枣林>杠柳林>草地>裸地.Horton模型适宜模拟贝壳砂生境的土壤入渗特征,灌木林土壤入渗性能好于草地.杠柳林和酸枣林的稳渗速率分别比裸地增加27.1%和5.4%,而草地比裸地降低76.6%.反映土壤蓄持水分的主要指标一类是土壤容重和孔隙度,另一类是土壤粗砂粒、粉粘粒分布和稳渗速率.贝壳砂土壤蓄水潜能综合评价为灌木林好于草地,酸枣林强于杠柳林,而裸地较差.

In order to investigate soil water storage and hold capacity as well as their influence factors under different vegetation types in shell island,soil infiltration process was studied in the field,basic physical parameters of soil and temperature response characteristic of soil water content were determined in laboratory. Soil water storage and hold capacity were assessed via fuzzy mathematics method of subordinate function. The results show that the soil total porosity under Zizyphus jujuba var. spinosa forest,Periploca sepium forest and grassland were 27. 0%,19. 3%and 10. 8% higher respectively than that of bare land,indicating that these three vegetation types could improve the soil permeability. At 30℃ and 50℃,soil water content went through 3phases according to the loss rate of soil water over time. First was the transient phase,then came the gradual change phase,and last was the plateau phase. The saturated soil water,the time needed for soil to reached constant weight and the loss rate of soil water were all as follow: Z.jujuba var. spinosa > P. sepium > grassland > bare land. The Horton model was suitable to simulate the characteristic of soil water infiltration under shell sand habitats. The soil infiltration property of shrubbery was better than that of grassland. Compared to bare land,the steady soil infiltration rate of P. sepium and Z. jujuba var. spinosa shrubbery increased by 27. 1% and5. 4%,respectively,and that of grassland decreased by 76. 6%. The key indicators of soil water holding capacity in shell sand habitats could be divided into two main classes: one included soil bulk density and porosity,and the other included the soil particle-size distribution of coarse sand,silt-clay and the stable infiltration rate. Soil potential water storage and holding capacity of shell sand soil was evaluated as follows: Z. jujuba var. spinosa > P. sepium,shrub forest >grassland > bare land.