不同生态修复草种对土壤水分蒸散的影响

Effects of Different Grasses for Ecological Restoration onSoil Evapotranspiration

以紫花苜蓿、结缕草、青绿苔草和无芒雀麦为试材,通过人工草地建植对退化植被进行生态修复,实时监测植被NDVI指数、根系体积、土壤含水量及水分蒸散动态变化,研究不同草种植被覆盖效果及其对土壤蒸散特征的影响,揭示植被土壤水分吸收的主要作用机理,以期为我国北方地区适宜生态修复草种选择提供参考依据。结果表明:4种生态修复草种均可快速增加植被生物量,减少非生长季土壤水分蒸散,但生长季植被生物量增加,土壤水分吸收增强,土壤蒸散明显增加,且不同草地月蒸散量峰值排序为青绿苔草(112.65 mm)>结缕草(107.42 mm)>紫花苜蓿(98.19 mm)>无芒雀麦(86.69 mm)。另外,植被根系分布及其体积变化是土壤水分吸收的关键,根系体积越大,分布越集中,土壤水分吸收能力越强,其中,青绿苔草与结缕草土壤水分吸收的主要区域在0~20 cm土层,紫花苜蓿与无芒雀麦在20~40 cm土层。综上所述,由于生长季植被增加土壤水分蒸散,建议北方干旱缺水地区生态修复过程中尽量选择水土保持能力强但水分消耗相对较少的植物种类,就供试植物优先选择无芒雀麦,其次是紫花苜蓿。

Medicago sativa,Zoysia japonica,Carex leucochlora,and Bromus inermis were used as experimental materials,ecological restoration of degraded vegetation was restored by artificial grassland constructing.The effects of different grassland cover on soil evapotranspiration and the main mechanism for water absorption of vegetation were studied by monitoring vegetation NDVI,root volume,water moisture content and soil evapotranspiration real-timely,in order to provide reference for suitable grasses selected of ecological restoration in North of China.The results showed that vegetation biomass increased quickly after all four types of ecological restoration grass were constructed,and soil evapotranspiration reduced obviously in non-growing season.But soil evapotranspiration increased greatly during growing season with vegetation biomass and water absorbed in the soil increasing.Then the peak values of monthly evapotranspiration of different grasslands were Carex leucochlora(112.65mm)>Zoysia japonica(107.42mm)>Medicago sativa(98.19mm)>Bromus inermis(86.69 mm).Moreover,it was every important for root volume and distribution on soil moisture absorbed.The capacity of water absorption for vegetation was stronger when root volume was greater and root distribution was more concentrated.In the experiment,the main space areas of Carex leucochlora and Zoysia japonica absorbing soil moisture were all 0-20cm layer of soil,and those of Medicago sativa and Bromus inermis were all 20-40cm layer of soil.In conclusion,grasses with more capacity of soil and water conservation and less soil moisture absorption should be selected during ecological restoration as far as possible.Bromus inermis was selected firstly,and then,Medicago sativain the experiment.