【作者】 张满清；

【导师】 李吉跃； 李世东；

【作者基本信息】 北京林业大学 ， 森林培育， 2004， 硕士

【摘要】 本篇论文对黄土高原地区退耕还林的现状、存在的问题和抗旱造林技术进行了阐述，并通过在温室可控条件下，对黄土高原地区6个主要造林树种的苗木在正常水分状况下的耗水特性进行研究，得到各种苗木在正常水分条件下的蒸腾耗水规律。同时结合典型地区的野外调查研究，分析不同配置的苗木生长情况、土壤含水率、容重、孔隙度和土壤养分状况，旨在为该地区进行退耕还林树种选择、提高造林成活率和合理的密度配置提供理论依据。 正常水分下，旱柳、白蜡、毛白杨、国槐、侧柏和油松苗木的耗水量和耗水速率日变化呈明显的单峰曲线，苗木的耗水量最大值和最大耗水速率出现在10：00～14：00之间，耗水量占白天的50％左右，苗木耗水以白天为主，白天的耗水量约占全天的85～95％。白天的耗水速率是夜晚的8.5～9.5倍。苗木日平均耗水速率晴天最大，阴天次之，雨天最小。在晴朗的天气，不论是日平均蒸腾速率、耗水量还是耗水速率，针叶树种(油松和侧柏)明显低于阔叶树种。 通过对多株苗木的耗水特性研究结果表明，同一树种不同密度的耗水速率，除旱柳以外，其它5个树种苗木都是盆栽1株白天平均耗水速率大于多株苗木的平均耗水速率，盆栽2或3株比盆栽1株苗木白天的平均耗水速率均有不同幅度的下降，但不论是盆栽1株还是多株，不同苗木耗水速率的大小排序不变：旱柳＞白蜡＞毛白杨＞国槐＞侧柏＞油松。由于树木的耗水量与耗水速率和叶面积的大小有关，在黄土高原地区退耕还林中应选择抗旱节水的树种(如油松和侧柏)并进行合理的密度配置。 通过野外调查，对两个典型地区退耕还林不同树种配置模式进行了效果比较，研究了植被对土壤系统水分和养分平衡的影响，在植被作用下，土壤有机质、全氮、全磷、全钾总量相对坡耕地有所增加，土壤养分状况得到不同程度的改善；同时，林地土壤水分相对坡耕地有不同程度的改善。植被恢复有利于水土保持，减少养分的损失，提高土壤肥力，并且能起到改善小生境，调节小气候的作用。在黄土高原地区采用抗旱技术对坡耕地进行退耕还林并不会造成土壤水分的减少，只要选择适宜的树种和注意造林密度，在合理树种配置的基础上进行植被恢复，不但不会引起土壤干化，反而有利于增加和保持土壤水分，改善当地的环境条件。更多还原

【Abstract】 In this paper, it was commented on the current situation, main problems and the technology of drought resistant for afforestation in the conversion of farmland to forest (CFF) project on the Loess Plateau. The water consumption of six main plantation tree species on the Loess Plateau under water supply normally was studied in greenhouse. The water consumption patterns of seedlings in normal water supply were observed. Moreover, it was also studied by analyzing of grow situation, soil water content, volume weight of soil, soil porosity, soil nutrient elements and chemical properties of different arrangement in typical field. Target of the researches is to meet the need in choice of tree species with lower water consumption, higher survival rates, and the reasonable spatial structure and stand density in CFF project on the Loess Plateau.The results of studies on water consumption of Pinus tabulaeformis, Platycladus orientalis ,Populus tomentosa, Fraxinus velutina, Sophora japonica and Salix matsudana Koidz in normal water supply showed that the daily variations in WCA and WCR of seedlings were clearly. The daily highest amount and rate of water consumption of seedlings was at 10:00-14:00. Moreover, the WCAs were half of that in whole day, the water was consumed mainly in daytime, and the daytime WCA of seedlings was occupied about 85% to 95% of the amount of whole day. The daytime WCR of seedlings in August was 8.5 to 9.5 times as much as that of night. The average hourly WCA in daytime of seedlings is highest in sunny weather, lower in cloudy day and lowest in rainy day. The results of research on water consumption properties of seedlings showed that the coniferous species such as Pinus tabulaeformis and Platycladus orientalis obviously lower than broadleaf tree species in average hourly WCA in daytime, WCAs and WCR .The results of research on different density showed that average hourly WCR indaytime of five seedlings aside from Salix matsudana Koidz were higher in single than that of in two or in three in the same species. That is to say , the average hourly WCR in daytime of seedlings in two or three were decreased in different extent than that of in single. Though seedlings in different density, the permutation of WCR of different seedlings is constant: Salix matsudana Koid>Fraxinus velutina>Populus tomentosa> Sophora japonica> Platycladus orientalis>Pinus tabulaeformis. It is very important to select tree species, which has lower water consumption and drought tolerance such as Pinus tabulaeformis and Platycladus orientalis, and set reasonable stand density in recovery and reconstruction of forest vegetation in CFF project on the Loess Plateau.The results of studies on the effect of different tree species arrangement on the typical field in CFF project showed that soil water content, soil organic substance, total of nitrogen, phosphorus and potassium in different arrangement were higher than that of sloping-farmland. And the soil nutrient elements has been improved in different extent than that of sloping-farmland. So recovery and reconstruction of forest vegetation would be advantageous of water and soil conservation, decrease in loss of soil nutrient elements, improved on soil fertileizer and adjusting micro-climate and micro-ecology condition. By application of drought-resistant afforestation technology in CFF project on the Loess Plateau, it wasn’t only decrease soil water content, but also increase soil water content only if selected suitable tree species and set reasonable stand density.更多还原