【作者】 陈平；

【导师】 张劲松；

【作者基本信息】 中国林业科学研究院 ， 生态学， 2014， 博士

【摘要】 复合农林业是华北低丘山区退耕还林工程建设的重要内容之一，林药复合系统作为农林复合系统的类型之一，在当地农业产业调整发展的过程中得到了广泛的应用。由于该地区气候干旱、土层瘠薄、灌溉条件较差，水资源短缺制约了林业及农业的可持续发展。因此，基于种间水分关系理论，研究林药复合系统水分生态问题，对当地林业生态建设、提高农民收入，促进生态与经济可持续发展具有重要的指导意义。本文以水和碳稳定同位素信息、树干液流及群体蒸腾等为指标，2011年-2013年在位于华北低丘山区的河南济源，试验研究株行距3m×8m核桃-菘蓝/决明子复合系统种间水分关系，旨在为该区发展高效、稳定的农林复合系统提供理论依据。结果表明：（1）核桃-菘蓝/决明子系统土壤水分呈现明显的时空变化规律。在垂直方向上，土壤水分随着土层深度的增加整体上呈现增加的趋势，0-10cm的表层土壤水分差异较大；在水平方向上，核桃-菘蓝/-决明子复合系统表现出位于核桃树干距离0.5m处土壤水分最大，距离南北两侧核桃树木中间处最小。由于核桃树的遮蔽作用，降低了土壤水分的蒸发量，间作系统土壤含水量较单作系统均有所增加，核桃-菘蓝间作系统土壤水分在2012年、2013年比单作菘蓝分别增加了36.5%和8.78%；核桃-决明子间作系统土壤水分在2012年、2013年比单作决明子分别增加了21.05%和16.10%。（2）揭示了核桃-菘蓝/决明子间作系统根系的空间分布特征。在垂直方向上，核桃根系主要分布在10-50cm土层中，占总量的60%以上，而菘蓝和决明子根系主要分布在0-30cm的土层中，根长密度分别占其总量的70%以上；水平方向上，间作系统中菘蓝和决明子根系距离树干距离越远，其分布越多，最大值均在距离南北两侧树木中间处。核桃根系在距离南北两侧树行越近，其分布越多。间作对林带根系有一定程度的影响，0-40cm土层中，单作核桃的根长密度和根表面积大于间作核桃，40cm以下土层，间作核桃根系的根长密度和根表面积较单作核桃的大，说明间作系统中核桃根系由于间作物的竞争发生了下移的现象。复合系统中150～250cm带距范围内的10～30cm土层为种间根系主要交错区，就根系分布而言，该范围土体是种间水肥主要竞争区域。（3）菘蓝生长时期，由于降雨较少，属于干旱季节，核桃-菘蓝间作系统中核桃树木主要利用土壤深层（30-80cm）中的水分，比例为约59.7%；决明子生长时期主要集中在7-9月份，降雨量较多，属于雨季，核桃-决明子间作系统中核桃树木主要利用土壤浅层（0-30cm）中的水分，比例约为69.9%。菘蓝和决明子均主要利用来自0-30cm浅层土壤中的水分。菘蓝生长苗期，尽管这个时期菘蓝的根系没有生长到深层土壤中，但在核桃-菘蓝间作系统中菘蓝有5.7%、9.7%的水分来源于土壤深层中，说明复合系统核桃具有“水力提升”作用。（4）通过称重法和稳定碳同位素方法对盆栽决明子/菘蓝的水分利用效率进行比较研究，结果显示，两种方法测定的决明子/菘蓝水分利用效率呈极显著正相关关系（P<0.01），说明利用稳定碳同位素方法测定决明子/菘蓝水分利用效率具有可行性。（5）核桃-菘蓝复合系统中，2012年核桃与菘蓝的耗水比例是0.70:1，二者分别占41.25%、58.75%。2013核桃与菘蓝的耗水比例是2.06:1，二者分别占67.40%、32.60%，核桃在生长时期两年的耗水量差异较小，说明2013年严重春旱对主要吸收浅层土壤水的菘蓝的生长产生了较大影响，对于依靠深层土壤水的核桃影响不大。核桃-决明子复合系统中，2012年核桃与决明子的耗水比例是1.79:1，二者分别占64.20%、35.8%。2013年核桃与决明子的耗水比例是1.42:1，二者分别占58.73%、41.27%。对比单作菘蓝，2012、2013年核桃-菘蓝复合系统可使菘蓝的耗水量分别降低45.29%、49.63%；对比单作决明子，2012、2013年核桃-决明子复合系统可使决明子耗水量分别降低55.84%、61.83%；对比清耕核桃园，2012、2013年核桃-菘蓝/-决明子复合系统在生长期可使核桃耗水量分别降低9.83%、6.86%。核桃用水高峰期在6-8月，该时期耗水量占主要生长季总耗水量的52%左右。菘蓝、决明子的用水高峰期分别在4-5月、8-9月，二者与核桃可以错开主要用水期。（6）核桃-菘蓝/-决明子复合系统中核桃、菘蓝和决明子的产量低于单作系统或清耕核桃园，但复合系统的总收入高于单作系统，2012年和2013年间作系统的总收入分别是单作核桃的1.47倍和1.24倍，分别是单作菘蓝和单作决明子的1.24倍和1.49倍。综上所述，核桃-菘蓝/决明子复合系统表现为深根木本植物和浅根药用植物以互补的方式利用不同层次土壤水分，复合系统中核桃遮阴明显改善了菘蓝和决明子的土壤水分状况、降低耗水量、提高水分利用效率及产值，在生长时期上也错开主要用水时期。故在地处半干旱季风气候的华北低丘山区，发展核桃-菘蓝/决明子复合系统具有可行性。以上研究对退耕还林地林药复合系统的结构配置及经营管理具有重要的理论指导作用。更多还原

【Abstract】 Agroforestry is one of the important approaches in turning the farmland into forestryprogramme. Tree and medical plant intercropping, as one of the agroforestry sytles, has beenwidely applied in the development of industry restructuring in this area. Seasonal drought,barren soil, and bad irrigation condition result in shortage of water resources in this area, andresultantly water deficit restrict sustainable development of foresty and agriculture. Thus, studyon water ecology of walnut-woad/cassia agroforestry system based on interspecific waterrelation can instruct forestry construction, improve farmer’s income, and promote thesustainable development of ecology and economy. In this paper, indices including stable waterand carbon isotope information, sap flow, and group tranpiration has been used to studyinterspecific water relation in walnut-woad/cassia agroforestry system of planting spacing3m×8m at low hilly area of north China in Jiyuan, Henan province during the year2011to2013.The above research aimed to provide thearetical basis for developing efficient and stableagroforestry system in this area, the results are as follows:（1）Soil water of each plantation pattern all showed obvious spatial and temporal variation.Vertically, soil water content increased with the increase of soil depth; The soil water content atsurface layer of0-10cm varied greatly; horizontally, soil water content in both walnut-woadand walnut-cassia intercropping systems were highest at the distance of0.5m to tree trunck,and lowest in the middle of two tree row. Shade effect of walnut trees decreased soil waterevaporation, which may explain why soil water content in the walnut-woad intercroppingsystem was36.5%and8.78%higher than, and in the walnut-cassia intercropping21.05%and16.1%higher than that in the sole woad or cassia crop system, respectively in the year2012and2013.（2）The spatial distribution of root in different systems was also studied. Vertically, walnutroot was mainly distributed at the10-50cm soil profile, accounting for more than60%. Whilemore than70%of woad and cassia roots (root lenth density) distributed at0-30cm soil profile; horizontally, woad and cassia roots increased with the increase of their distance to tree rows inthe intercropping system. Crop had more roots in the middle of two tree row. Intercroppingalso influence the distribution of tree roots. The root lenth density and root specific area ofintercropping walnut was less than that in the sole walnut system at0-40cm soil profile, butmore than that in the sole system below40cm soil layer. The above results indicated thatwalnut root in the intercropping system shift to a deeper soil layer as a result of the competitionof intercroped crops. In the intercropping system, both tree and crop roots distributed roots atthe range of150~250cm to tree row in10~30cm soil layer, thus, this area may be the mainsoil water and fertilizer competition area.（3）Rainfall was rare during the growth of woad, and it was dry season of a year. Walnutin the walnut/woad intercropping mainly use water from deep soil layer (30-80cm), accoutingfor59.7%of its total water use; cassia mainly grown during July to September, and it rained alot in this peroid, and walnut in the walnut/cassia intercropping mainly use water from shallowsoil layer (0-30cm), accouting for69.9%of its total water use. Both woad and cassia weremainly use shallow layer soil water. During seedling peroid of woad,5.7%and9.7%of theirwater were from the deep soil layer of the intercropping system, but no woad roots were foundin the deep soil profile, which indicated that walnut root had hydraulic lift effect.（4）Water use efficiency (WUE) of potted cassia/woad were researched through theweighing method and stable carbon isotope method simutaneously. The results showed thatWUE calculated by the two methods were positively related (P<0.01), which indicated thatmeasurement of cassia/woad WUE with stable carbon isotope technique is feasible.（5）In the walnut-woad intercropping, the ratio of water used by walnut and woad was0.7:1, accounting for41.25%and58.75%in the year2012; the growth of woad mainly absorbshallow soil water was affected because of spring drought, but a litter influence to walnut relyon deep soil water, while the ratio was2.06:1in the following year in2013, and walnut andwoad accounted for67.4%and32.6%, respectively. In the walnut-cassia intercropping, theratio of water used by walnut and cassia was1.79:1, accounting for64.2%and35.8%in the year2012; and the ratio was1.42in the following year in2013, and walnut and woadaccounted for58.73%and41.27%, respectively. Woad intercropping with walnut reduced45.29%and49.63%of water use respectively in2012and2013, comparing to sole indigowoad.Cassla intercropping with walnut reduced55.84%and61.83%of water use respectively in2012and2013, comparing to sole cassia. And water use of walnut trees form walnut-Woad/cassia intercropping reduced9.83%and6.86%respectively in2012and2013, comparing tosole walnut. Peak water use period of walnut appeared during Jun-Aug, accounted for52%ofthe total water consumption of the growing season. While, woad and cassia consumed watermainly during April to May, and August to September, respectively, they avoid main water useperiod.（6）Although yield of each compoment in the intercropping system was less than the solesystem, the total income of the agroforestry was higher than that of the sole systems, for walnut,the yield in the intercropping system were1.47and1.24times of that in the sole walnut systemin2012and2013, respectively, and for woad and cassia in the intercropping system were1.24and1.49times of that in the sole crop system in2012and2013.According to the above research, deep-rooted trees and shallow-rooted medicine plant inthe walnut-woad/cassia intercropping used water in a complementary manner to use differentlevels of soil moisture. Shade of walnut trees improved water status of crops underneath,reduced their water use and increased their water use efficiency and income. Trees and cropsavoid main water use period. Therefore, it’s feasible to develop walnut-woad/cassiaintercropping in the low hilly area of north China. The above research can instruct structureconfigration and management of agroforestry system in the turning crop to forest program.更多还原