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了解林农复合系统的种间水分关系至关重要。该文通过稳定氘同位素研究了华北低丘山区核桃(Juglans regia)-菘蓝(Isatis tinctoria)/决明(Senna tora)复合系统各组分的水分来源,试图明确该果药复合系统的种间水分利用策略,为该区林农配置模式的选择提供理论依据。研究结果表明:果药复合系统的土壤含水量明显高于单作菘蓝和单作决明地块,在2012年、2013年上半年比单作菘蓝高26.74%和7.93%,在下半年比单作决明高17.39%和13.65%。在果药复合系统内部,土壤含水量以核桃树行中间位置的最低、树行北侧和树下最高。在各个土层深度,单作系统的土壤水氢稳定同位素比率(δD值)均比复合系统的高。在菘蓝生长时期的春旱期,复合系统中核桃的大部分水分来源于30–80 cm深层土壤水,表明此时期核桃表层根系活性不高;而决明生长时期正值雨季,此时核桃优先利用雨水补充的0–30 cm浅层土壤水、表层根系活性增强。在任何生长时期,菘蓝和决明85%以上的水分都来自浅层土壤水。在菘蓝苗期,其根系尚未扎入深层土壤中,单作菘蓝的水分完全来源于浅层土壤,而在2012年间作菘蓝却有5.7%的水分来自于深层土壤,在更为干旱的2013年该比例上升到9.7%,该结果证实了核桃在旱季存在“水力提升”作用,供浅根系作物吸收利用,并且越干旱,该水力提升作用越强。在华北低丘山区核桃-菘蓝/决明复合系统中,深根性核桃改善了复合系统的土壤水分状况,在旱季主要利用深层土壤水以避开与浅层作物的水分竞争、并能将深层土壤水提升至浅层土壤供菘蓝吸收利用,核桃与两种药材表现为水分互利关系,因而该模式适合在该地区发展。
It is of crucial importance to understand the interspecific association of water in the forest system. In this paper, the source of moisture in each component of the Juglans regia-Isatis tinctoria / Senna tora composite system in the hilly region of North China was studied through stable deuterium isotopes, Water use strategy, provide theoretical basis for the choice of forest and peasant allocation pattern in this area. The results showed that the soil moisture content of composite system of fruit and drug was significantly higher than that of monocrotaline and monocrotagalline, and was 26.74% and 7.93% higher than that of monocotyledons in 2012 and the first half of 2013 respectively. Single high decision-making 17.39% and 13.65% high. In the composite system of medicinal plants, the soil water content is lowest in the middle of the row of walnut trees, and highest in the north side and the tree of the tree branches. At all soil depths, the single-crop system has a higher water-stable isotope ratio (δD value) than the composite system. In the spring drought period of the growth period, the majority of walnut in the composite system originated from 30-80 cm deep soil water, indicating that the root activity of walnut was not high at this period. Preferential use of rainwater supplemented 0-30 cm shallow soil water, the surface root activity increased. In any growing season, more than 85% of the rays of the blue and cassia come from shallow soil water. At the seedling stage, the root system did not penetrate into deep soil. The water of monocots was entirely from the shallow soil. However, 5.7% of the water from the deep soil was from the deep soil in 2012, The proportion increased to 9.7% in 2013, which confirmed the existence of “hydraulic lift” effect of walnut in the dry season for absorption by shallow root crops, and the drier the stronger the hydraulic lifting effect. Deep walnut improved the soil moisture status of the compound system in the walnut - Rehmannia glutinosa / Cassia obtusifolia complex in the hilly region of North China. In the dry season, deep soil water was mainly used to avoid the water competition with the shallow crops, Soil water increased to shallow soil for the absorption and utilization of blueberry, walnuts and two herbs showed a water-mutually beneficial relationship, so this model is suitable for development in the region.