北京山区松栎混交群落的植物水分来源研究

Water Sources of the Oak-pine Mixed Community in Beijing Mountainous Area

为探究北京山区典型植物的水分竞争关系,通过测定雨季松栎混交群落内5种植物（栓皮栎、油松、荆条、构树、小叶鼠李）的枝条水及不同水源的氢氧同位素值和土壤含水量,利用多元线性混合模型（Iso-source模型）分析了不同植物对不同水源的利用比例.结果表明：栓皮栎主要利用60-100cm深层土壤水,利用比例为55.7%;油松的主要水分利用来源于表层0-20cm土壤水分,水分利用比例占所有水分来源的2/3;林下灌木荆条主要水分来源也为表层0-20cm的土壤水分,利用比例为50.27%;构树对各水分来源的利用较均匀;小叶鼠李主要对40-100cm的深层土壤水分利用较多,水分利用比例达到70%以上.栓皮栎、小叶鼠李倾向于利用深层土壤水,油松、荆条倾向于利用表层土壤水.因此,栓皮栎、油松、构树三者可以形成松栎混交林,以减少植物群落在水分来源中存在的竞争;而油松与荆条、栓皮栎与小叶鼠李水分竞争较大,不易混交.

To explore the water competitive relationship among topical plants in Beijing mountainous area,this research measured the stable isotopic values of hydrogen and oxygen of water in the branch of five plants（ Quercus variabilis、Pinus tabulaeformis、Vitex negundo、Broussonetia papyrifera、Rhamnus parvifolia） in oak-pine mixed community during the rainy season,different water sources and soil water content. Different water utilization proportions of different plants were analyzed through multi-source linear mixed models（ Iso-source）. The results showed：Q. variabilis consumes water mainly from 60 - 100 cm soil layers with 55. 7% utilization rate.Pinus tabulaeformis up-takes most water from top layers（ 0 - 20 cm） with 2/3 of all sources of water being utilized. As for shrub,V. negundo also absorbs 0 - 20 cm depth soil water with50. 27% utilization rate. B. papyrifera uses all kinds of water sources evenly. R. parvifolia extracts most depth soil water,including 40 - 100 cm depth,with over 70% rates. Q. variabilis and R. parvifolia tend to utilize deeper soil water while P. tabulaeformis and V. negundo are more likely to absorb surface soil water. Q. variabilis、P. tabulaeformis and B. papyrifera can be mixed in afforestation to reduce the competition of plant community in water source. The water competition between P. tabulaeformis and V. negundo has been observed,so they cannot be mixed,which is same as Q. variabilis and R. parvifolia.