本文针对黄土高原水土流失综合治理中植物配置存在的关键问题，阐述了黄土高原的植物种类及水土流失治理中的高效水土保持植物种类与分布；在强调遵从自然规律、经济规律和科学规律的基础上，提出了黄土高原高效水土保持植被的选择与配置必须遵从适地适树、水量平衡、乡土植物、经济生态、密度调控和自然恢复等6项原则，列举了黄土高原沟壑区、黄土丘陵沟壑区、黄土丘陵河谷盆地区等不同立地条件类型适生树种林种配置模式；做到因害设防、除害兴利，最终实现人与自然和谐。

In this paper, plant species and efficient water and soil conservation plant species and its'' dis-tribution in the Loess Plateau are elaborated aiming at the key issues of plant arrangement for the com-prehensive soil erosion controlling. In emphasizing the basis of compliance with the laws of nature, eco-nomic and scientific laws, the six principles, which are the matching site with trees, balancing between atmospheric precipitation and evapo-transpiration, planting native plants species, efficient economic and ecological plants, planting density controlling and vegetation natural recovering, are proposed to efficient plants arrangement for soil and water conservation in the Loess Plateau. Different site conditions and its'' forest or tree species suitable arrangement modes are cited at the gully region, loess hilly region, and loess hilly valley-basin region of the Loess Plateau. Controlling because of soil erosion, eradicating harmful things and setting up the business be

[目的]探索农耕地撂荒对土壤微量元素演变特征的影响，为该地区植被恢复中土壤质量评价和生态恢复的持续健康发展提供科学依据。[方法]以黄土丘陵区不同撂荒年限的坡耕地为研究对象，分析农耕地撂荒后不同坡向土壤4种有效态微量元素的变化趋势。[结果]黄土丘陵区坡耕地撂荒后，阴坡由于土壤温度较低，含水量较大，植被生长旺盛。有机碳、全氮、有效锰、有效铁、有效锌含量变化规律性较强，表现为在演替前期变化较小，而后期随撂荒年限的延长而显著增加，有效铜则随撂荒年限呈降低趋势。阳坡土壤有机碳、全氮及4种有效态微量元素含量则随年限呈波动变化。不同演替阶段土壤微量元素密度变化不同，阳坡土壤有效铁和有效锌密度在演替前10年明显高于阴坡，而在10年后显著低于阴坡；有效铜密度在前5年略低于阴坡，5年后明显高于阴坡。[结论]黄土丘陵区坡耕地撂荒20年后，虽然4种土壤有效态微量元素含量有所提高，但仍处于低或极低水平，因此黄土丘陵区通过自然演替来改善土壤微量元素状况还需要较长的时间。

[Objective] The research was made to provide a scientific guidance for the sustainable development of ecological restoration and the evaluation of soil quality by studying the effect of abandoned cropland on soil trace elements in the hilly-gully region of the Loess Plateau.[Method]The present study investigated the changes of four available trace elements at different slope aspects during succession on abandoned cropland in the loess hilly region. [Result] The results showed that during the vegetation succession on abandoned cropland, the content of organic C, total N, available Mn, available Fe, available Zn in this shady slope presented a significant regular variation due to the high soil moisture favorable vegetation conditions, showing no significant difference at the early stage of succession while increased with the increasing years at the later stage. Available Cu exhibited a decrease trend with years. Organic C, total N, and four available trace elements in the sunny slope flu

为探索陕北黄土丘陵区梨枣的抗旱性与耐旱能力,以大规格盆栽梨枣(Ziziphus jujuba Mill.cv.Lizao)2年生苗木为试验材料,在连续不供水情况下研究了梨枣的萎蔫到致死过程。依据干旱缺水后枣树生长衰退过程中的特征将枣树萎蔫致死分为:暂时萎蔫、初始萎蔫、表征永久萎蔫及耐旱致死四个阶段。结果表明:梨枣的初始萎蔫系数在2.017%~3.054%之间,平均为2.494%;表征永久萎蔫系数在1.199%~1.998%之间,平均为1.489%,永久萎蔫系数在1.250%~1.489%之间;耐旱致死点为1.250%,致死时间为135±11 d。试验结果证明枣树是一种十分抗旱的树种,在半干旱黄土丘陵区枣树不会出现干旱致死。

In order to explore the drought -resistant ability of pear jujube ( Ziziphus jujuba Mill .cv .Lizao ) in Loess Plateau region of northern Shaanxi ,a pot experiment was conducted with 2-year old seedlings as the material ,and its process from wilting to death was investigated under continuously unirrigated condition .The degenarative process of pear jujube under unirrigated condition was classified into four periods :temporary wilting ,initial wilting ,apparent permanent wilting and drought caused death . The results showed that the initial wilting coefficient of pear jujube was between 2 .017% and 3 .054% with an average of 2 .494% ;the apparent permanent wilting coefficient was between 1 .199% and 1 .998% with an average of 1 .489% ;the permanent wilting coefficient was between 1 .250% and 1 .489% ;the drought lethal point was 1 .250% and the lethal time was 135 ± 11 days .It was concluded that pear jujube was a kind of drought-resistant fruit tree ,and it could not become

黄土丘陵区特别是沟道复杂的地形为沟道小流域土壤有效储水量计算带来了困难。基于黄土丘陵区园则沟小流域2010—2012年土壤水分监测数据，采用时间稳定性分析和观测算子结合的升尺度方法，通过坡面单个监测点土壤有效储水量估算小流域不同尺度（坡面、沟道及小流域）土壤有效储水量。其中2010和2011年数据用于时间稳定性分析、观测算子构建以及坡面、沟道和小流域土壤有效储水量估算，2012年数据用于对其验证。结果表明通过坡面时间稳定点（单个点）土壤有效储水量不仅能够较为精确地估算坡面土壤有效储水量，也能通过构建观测算子较为精确地将其转换为沟道和小流域土壤有效储水量。验证结果表明，时间稳定点以及观测算子具有较高稳定性。

The complex topography of the hilly area of the Loess Plateau (especially gullies) leads to the difficulty of calculating watershed-scale available water storage (AWS). Based on soil moisture datasets from 2010-2012 in the Yuanzegou catchment of the Loess Plateau, this study attempted to estimate AWS of hillslopes, gullies and watershed from one single sampling location on the hillslopes for each layer, by coupling time stability analysis with observation operators. The AWS datasets in 2010 and 2011 were used for time stability analysis, development of observation operators and estimation of AWS of hillslopes, gul?lies and catchment. The AWS datasets in 2012 were used for validation. The results show that the AWS of hillslopes can be accurately estimated through that of one single hillslope time-stable location for each depth. Furthermore,the AWS of gullies and catchment are also well estimated from the hillslope time-sta?ble location by using the method of observation operators. The v

黄土丘陵区是我国1999年实施的以退耕还林为中心的生态建设工程重点地区之一。文中以文献和农户调查数据为基础,对黄土丘陵区特别是陕北安塞县,生态建设对其植被恢复、粮食生产、农民收入的影响进行了梳理和总结,并分析了农户对生态建设的认知与响应。研究认为,生态建设显著促进了区域的植被恢复,增加了退耕农户的收入,得到了农户的积极响应和参与。由于退耕地多为劣质耕地,坡地退耕对区域粮食生产影响很小,但却促进了土地的集约经营、农业结构调整和农村劳动转移,改变了农户的收入结构。建议国家继续推进生态建设,扶持农户梯田和坝地建设,发展高附加值的农业产业,提高农民的收入,促进农民的口粮安全,保证生态建设取得的成果。

The Hilly Loess Plateau in Northwestern China is a key region for the ecological construction program,financially supported by the government to promote the restoration of degraded land by converting slope farmland to forest or grassland.After the implementation in 1999,this program stimulated various changes in the physical environment,food grain production and rural income.In this paper we discussed effects of the program on the above aspects,and identified the awareness and responses of local farmers to the program in the Hilly Loess Plateau with special focuses on Ansai County,based on literature and household survey data.It was found that the ecological construction program markedly promoted the vegetation restoration and an increase of farmer income,and thus received a positive response and active participation of local farmers.Since the converted farmland was mostly steep slope land with low yield,the farmland conversion had no adverse effects on the food grain production,but it