【作者】 成向荣；

【导师】 黄明斌； 邵明安；

【作者基本信息】 中国科学院研究生院（教育部水土保持与生态环境研究中心） ， 土壤学， 2008， 博士

【摘要】 黄土高原农牧交错带以干旱和半干旱气候类型为主,降水稀少,植被生物量普遍偏小、冠幅不大,大多数植被呈斑块状分布。研究黄土高原稀疏人工植被覆盖下土壤-植被-大气系统水分运动和转化规律,可揭示该区代表性生态系统植被的耗水特性,对合理规划、布局和重建可持续发展的生态系统有重要意义。本文通过调查典型乔灌木树种和草种的细根空间分布特征,监测SVAT系统水分平衡分量,系统掌握了不同植被类型水分转化特征和规律;并应用SHAW模型模拟不同植被覆盖下水分和能量在SVAT系统各层次间的传输特征,分析典型植被长期耗水过程,初步探讨该区坡面适宜的植被覆盖度。本研究的主要结论如下:(1)六道沟流域主要乔灌木树种0-100 cm土层中细根分布较多,100 cm以下逐渐减少。刺槐细根分布主要集中在0-340 cm;沙黄土柠条和沙柳细根分布主要集中在0-300 cm,而沙地柠条和沙蒿细根分布相对较浅,主要集中在200 cm以内。就0-100 cm土层中细根分布的比例而言,沙地柠条>沙蒿>黄土柠条>沙柳>刺槐。(2)不同土地利用方式对剖面土壤水分有重要影响。油松和沙蒿的土壤水分状况较好,刺槐、小叶杨、沙柳、柠条和沙柳-柠条-沙蒿混交林土壤含水量较低,其中以0-200 cm土层较为明显。不同土质上生长的20多龄柠条均大量消耗了0-200 cm土层的土壤水分,但对200 cm以下土壤水分影响不尽相同,硬黄土深层土壤水分条件相对较好,其次为披沙地和风沙土,沙黄土深层土壤水分被大量消耗,水分状况最差。3-5年生的苜蓿大量消耗0-280 cm土层土壤水分,第3年土壤储水量只有农地的一半。(3)不同植被覆盖下水量平衡分析表明,整个观测期沙黄土上生长的油松和柠条土壤水分变化基本保持平衡,平均蒸散量/降水量(ET/P)之比分别为97.6%和98.3%;而3-5年生的苜蓿土壤储水呈负平衡,平均ET/P高达107.5%。风沙土上生长的柠条、沙柳和沙蒿土壤储水也基本保持平衡,平均ET/P变化在95.7%-98.8%;刺槐、小叶杨和沙柳-柠条-沙蒿混交林蒸散量略高于同期降水量,平均ET/P分别为103%、101.6%和101.1%。(4)通过验证SHAW模型可以很好地模拟黄土高原农牧交错带人工植被水分和能量动态变化。对苜蓿、柠条和油松小区剖面土壤水分模拟效率(ME)在0.54-0.82,相对平均绝对误差(RMAE)在9.2%-12.9%;对短波辐射、地表净长波辐射和净辐射模拟值与实测值的相对平均绝对误差(RMAE)分别为11.3%、18.4%和20.2%。能量平衡组成分析表明,阴坡苜蓿地、短花针茅地和谷子地能量主要消耗于蒸散发的潜热,而阳坡柠条林地和油松林地能量的消耗主要是感热。(5)根据土壤允许流失量和植物对土壤水分的适度消耗与盖度的关系,对该区代表性灌草植物适宜生长冠层盖度进行了初步研究,确定六道沟流域坡地适宜的苜蓿和柠条盖度分别为33%-40%和25%-32%。更多还原

【Abstract】 In the farming-pastoral zone of the Loess Plateau, with arid and semi-arid climate and scarce precipitation, the majority of vegetation distribution is patchy with lower biomass and relatively small canopy. Research on the water movement and transformation of soil- vegetation-atmosphere-transfer can reveal the water consumption characteristics of the representative sparse vegetation in the region, and it will help to establish sustainable development ecosystem. In this study, in order to understand the water consumption and movement in different SVATs, the spatial distribution of fine roots of typical trees, shrubs and grasses species were investigated, the components of SVAT system water balance were monitored. In addition, SHAW model was used to simulate energy and water transmission among the components of SVAT system under different land use patterns, long-term water consumption process of typical vegetation were also simulated, and the suitable vegetation coverage were determined by the relationship between vegetation and soil water in this area. The main conclusions of this study are as follows:(1)More fine roots of representative arbors and shrubs in the Liudaogou Basin occurred in the upper 100 cm soil layer and fewer were below 100 cm. The majority of fine roots of Robinia pseudoacacia concentrated in 0-340 cm; for Caragana korshinkii which grown in loess soil and Salix psammophila were both 0-300 cm; the fine roots of C. korshinkii in sandy soil and Artemisia ordosica mainly concentrated in 0-200 cm. The proportion of fine roots in 0-100 cm of total fine roots was C. korshinkii in sandy soil>A. ordosica>C. korshinkii in loess soil> S. psammophila>R. pseudoacacia.(2)The soil water in profile was greatly affected by different land use patterns. The soil water condition was better in P. tabulaeformis and A. ordosica land, but R. pseudoacacia, P. simonii, S. psammophila, C. korshinkii and S. psammophila-C. korshinkii- A. ordosica were suffered different levels of water stress, especially the soil moisture content was very low in 0-200 cm soil layer. 20 years old C. korshinkii grown in different soils all strongly consumed the soil water in 0-200 cm, but they had different effect on the soil water below 200 cm. The soil water condition was relatively good in red clay soil and hard loess soil, followed by aeolian soil and sandy soil, the lower soil water occurred in sandy loess soil. 3-5 years old M. sativa used more water in 0-280 cm soil layer, the soil water storage was only half of the farmland at the 3th year.(3)The water balance of different land use patterns indicated that the soil water kept balance for the P. tabulaeformis and C. korshinkii which grown in silt loam soil over the whole study period, the average evapotranspiration/precipitation (ET/P) was 97.6% and 98.3%, respectively; but the soil water storage was deficit for 3-5 years old M. sativa land, and the average ET/P was 107.5%. The soil water also remained balance for the S. psammophila, A. ordosica and C. korshinkii which grown in sandy soil during the same period, the average ET/P changed from 95.7% to 98.8%; the average evapotranspiration for R. pseudoacacia, P. simonii and S. psammophila-C. korshinkii-A. ordosica lands slightly exceeded precipitation, the average ET/P were 103%, 101.6%and 101.1%, respectively.(4)SHAW model could be used to simulate the dynamics of solar radiation and soil water. The simulated net solar radiation was in good agreement with the measured values, and the relative mean absolute error (RMAE) was around 21%. The soil water model efficiency (ME) for P. tabulaeformis, C. korshinkii and M. sativa land over two growing seasons was from 0.54 to 0.82, RMAE changed between 9.2% and 12.9%. Energy balance showed that, the major consumption of energy was the latent heat of evapotranspiration for M. sativa, S. breviflora and Millet at the shade slope, but the energy consumption was mainly sensible heat for P. tabulaeformis and C. korshinkii at the sunny slope.(5)Considered the relationship between the suitable amount of soil erosion and moderate soil water consumption by plants and the vegetation coverage, the suitable coverage for M. sativa and C. korshinkii in hillslope was 33%-40% and 25%-32%, respectively.更多还原