不同植被类型人工绿地土壤饱和导水能力、持水特征的比较

营造人工绿地是建设海绵城市的重要措施之一。人工绿地的蓄水消洪功能主要受土壤的入渗和保水能力影响且往往因植被类型不同而不同。以贵阳市花溪区城镇绿化带的乔木林、灌木林、草地3类典型人工绿地为研究对象，测定雨季和旱季0 ~ 10 cm、10 ~ 20 cm、20 ~ 30 cm土层的饱和导水率及其体积含水量，通过比较和分析不同植被绿地土壤入渗和保水特征，评价三种人工绿地蓄水消洪能力。结果表明:土壤饱和导水率以乔木绿地最大、灌木绿地居中、草地绿地最小，不过灌木和草本绿地差异较小；影响饱和导水率的主要因素是土壤容重、总孔隙度、毛管孔隙度以及砂砾含量。土壤体积含水量在雨季以乔木绿地最高、草地次之、灌木绿地最小，旱季以灌木绿地最高、草地次之、乔木绿地最小；雨季植被耗水以乔木最多，但受其冠层遮阴影响，地面水分蒸发相对较少；旱季各类型绿地土壤水分消耗速率差异不大，相比较而言草本植物水分消耗更少。综上所述，灌木绿地土壤保水能力强、旱季水分蒸发速率较小，乔木绿地土壤持水能力强、雨后保蓄水分多，因此，从保水、蓄水和耗水角度考虑，营造城市人工绿地应优先选择乔木和灌木植被并且采取针对性的保护措施，使之尽快发挥作用。

Comparison of Saturated Water Carrying Capacity and Water Holding Capacity of Artificial Green Land With Different Vegetation Types

Artificial greenspace is one of the important measures to build sponge city, which has the function of water storage and flood control. Its main influencing factors are soil infiltration and water conservation capacity, which different among vegetation types of greenspace. In order to explore the different influences of vegetation types on soil infiltration and water conservation capacity, three types (arbor, shrub and grass greenspace) of greenspace in Huaxi district of Guiyang city were selected. The saturated hydraulic conductivity and volumetric water content of shallow greenspace soil (0 - 10 cm, 10 - 20 cm, 20 - 30 cm) during rainy and dry seasons were analyzed in this study. The results showed that the soil saturated hydraulic conductivity was the largest in arbor greenspace but the smallest in grass greenspace, and small difference was found between shrub and grass greenspace. The saturated hydraulic conductivity was mainly affected by soil bulk density, total porosity, capillary porosity, non-capillary porosity and rock fragment content. In rainy season, the volumetric soil water content in arbor greenspace was the highest, followed by grass greenspace, and shrub greenspace was the lowest. Although arbor consumed more water, its canopy shading limited the evaporation of soil water. In dry season, the volumetric soil water content in shrub greenspace was the highest, followed by grass greenspace, and arbor greenspace was the lowest. During dry season, the temperature is relatively low, the evaporation rates of soil moisture of all types of greenspace are similar to each other. Due to the root characteristics of herbaceous plants, the grass greenspace consumed much less water in dry season. In conclusion, shrub greenspace has strong soil water conservation capacity which exhibited small evaporation during drought, and arbor greenspace has strong water holding capacity which stored most water after rainfall. We suggest to design more arbor and shrub greenspace and to set up protection measures in the early stage of artificial vegetation construction to reduce human interference.