【作者】 孙旭；

【导师】 高永； 刘静；

【作者基本信息】 内蒙古农业大学 ， 水土保持与荒漠化防治， 2009， 博士

【摘要】 本论文以河套灌区小美旱杨P. Popularis’〔Populus simonii×（Populus pyramidalis +Salix matsudana）cv.‘Poplaris’〕农田防护林为研究对象,对小美旱杨蒸腾耗水特性、盐分离子的吸收特性、防护林对林内土壤盐分积累及平衡、农田防护林的更新龄、防护林防护效益等问题进行了研究,并对现有防护林的模式下的防护效益作出综合评价,主要成果及结论如下:（1）影响小美旱杨的蒸腾耗水的主要环境因子为树木的林龄、造林苗木类型、昼夜变化、气象等。林龄大的树冠大,生长旺盛,代谢强烈蒸腾耗水多;萌生苗根系大,吸水能力强,萌生苗比扦插苗的耗水多,夜间,林带蒸腾减弱,趋于停止,在持续干旱地区,地下水位逐日降低,蒸腾减弱,耗水减小。树龄大的树木蒸腾耗水量多,未灌水比正在灌水条件下的日蒸腾耗水量多。（2）小美旱杨对K⁺、Ca²⁺、Na⁺、Mg²⁺具有较强的吸收选择性,均通过选择吸收K⁺和其他营养元素,抑制过多的Na⁺进入根系。但是,对Na⁺的排斥作用有限,盐胁迫下小美旱杨对进入根部过多的Na⁺,除了滞留在根部外,还在干中大量滞留,使枝、叶中Na⁺与营养元素之比保持较稳定的低值。（3）小美旱杨防护林达到防护成熟后,一年的田间减盐作用相当于从造林至防护成熟的全部林下积盐量,其节水作用,相当于5月中旬、8月、9月上旬在农田中增加一场中雨。对于树木-土壤-潜水系统,杨树耗水所含盐分离子的90%左右积累在林下的土壤-潜水系统中。（4）在河套灌区的立地条件下,小美旱杨农田防护林的初始防护成熟龄为9年,数量成熟龄为12年,经济成熟龄为15年,工艺成熟龄为15年;其适宜的更新龄为14年。（5）小美旱杨防护林减少林网内土壤蒸发的主要机理按影响程度排序为:空气温度因子>空气湿度因子>风速、辐射平衡值及土壤温度梯度。灌区的小美旱杨防护林应通过隔带间伐,将现行的100m主林带间距增至200m,主林带间距增大后,其防风、水文和热力效应基本不变,可实现灌区节水减盐的目的。按造林9年推算,小美旱杨防护林的节水量和年均减盐量为:146m³/hm². a和170kg/hm².a。（6）防护林影响防护区水量平衡的因子为:林带耗水量、田间减少土壤蒸发导致的节水量;影响防护区盐分平衡的因子为:防护林减少田间土壤蒸发所产生的田间耕作层减盐量、林带耗水导致的林下土壤积盐量、林带采伐减盐量。小美旱杨防护林能够有效减少灌区的盐分积累,并减少水资源的无效消耗,其节水作用对农业生产有重要意义。更多还原

【Abstract】 With P. Popularis’〔Populus simonii×(Populus pyramidalis+Salix matsudana) cv.‘Poplaris’〕Farmland Shelterbelt in Hetao Irrigation Area as test material , The study focuses on the water consumption characteristics, salt ions absorption characteristics, renewal age of Farmland Shelterbelt, and made a cpmprehensive assessment on comprehensive benefit. The main results were as following:(1)〔P. simonii×(Populus pyramidalis+Salix matsudana) cv.‘Poplaris’〕has a strong absorption selectivity on K+、Ca 2+、Na +、Mg2+, through absorbing K+ to prevent other Nutrient Elements, inhibiting excessive Na + enter root. However, the inhibition effect was limit, the root salt concentration was higher than CK when in high salt concentration envioronment. The excessive Na +also existed in stem, so that Na+/ Nutrient Elements keep a low level.(2) One year after Farmland Shelterbelt was mature , the salt decreacing effect account to accumulative salt amount from early stage to mature stage, equal to the total precipition of mid-May,August and September. The 90% of salt ion was accumulated in the soil ground water system, planting〔P. simonii×(P. pyramidalis+Salix matsudana) cv.‘Poplaris’〕on large scale has the tendency to increace the salt content of local area soil-ground water system.(3) In irrigation area site condition, P. Popularis’protective manturity、numerical maturity、economic maturity、techniques and regeneration age were 8a、13a、15a、15a、15a.(4) The order of affecting factors to evaporation degree was: air temperature>air humidity > wind speed,radiation trimmed and soil temperature gradient. The main forest belt should be intermediate cut to increase spacing from 100m to 200m, as a result, the wind controlling, hydrology and thermal benefit had changed seldomly, so as to implement water conservation-salt reduction purpose. The amount of water conservation and annual salt reduction were 146m~3/hm~2. a and 170 kg/ hm~2. a。In present Farmland Shelterbelt construction theory and comprehensive assement, water balance affect factor is shelterbelts water consumption, water conservation amount owing to reducing soil evaporation . The salt balance affect factor is field tillage salt reduction amount, understory accumulative salt amount, forest belt cutting salt reduction amount, P. Popularis’Farmland Shelterbelt can decrease salt accumulativetion effectively, and reduce soil ineffective evaporation, the water conservation effect of which play an important role in agriculture production.更多还原