【作者】 薛敏；

【导师】 张文辉；

【作者基本信息】 西北农林科技大学 ， 森林培育， 2011， 硕士

【摘要】 本文以延安公路山阴坡30年生人工刺槐林为研究对象,测定刺槐群落中12种优势植物在林内、林外的水分关系参数,分析刺槐林优势种在一个生长季(初期、旺盛期和末期)的水分利用特征和平衡机制,根据优势植物在群落中不同水分调节策略,进行水分利用功能群划分,阐述不同植物水分利用多样性与群落稳定性的关系。主要研究结论如下:1.群落中优势植物水分平衡能力呈现多样性。在一个生长季不同时期(5,7,9月)刺槐林内12种优势植物水势日变化基本一致,从4:00到21:00,水势值呈“高-低-高”趋势变化,基本呈抛物线形,与温度、光照强度负相关。不同生境条件下植物水势不尽相同,同一生境中的不同植物水势值不同;同一植物林内水势日变化幅度小于林外。2.不同优势植物在持水力和抗脱水能力上表现出多样性。不同生长时期,刺槐林优势植物水分亏缺(自然饱和亏缺,水分临界饱和亏缺,自然需水程度)平均值均表现为林外大于林内;不同植物水分亏缺值差异性明显;不同生境12种优势植物水分亏缺值变化幅度也不相同。3.不同植物在面对干旱环境,调节体内水分平衡方式是多种多样的。不同生长时期,植物为了适应干旱的环境,会降低ψssat,ψstlp和RWCtlp,增加εmax实现体内水分平衡。但在相同生境条件下,12种优势植物各水分关系参数表现出多样性;不同生境中的同一植物在不同季节水分关系参数的变化幅度并不相同。4.植物水分平衡参数随季节变化差异明显,表现出丰富的多样性。12种优势植物水分参数随季节变化呈现一定规律性,从5月到7月,再到9月,水势值呈“高-低-高”趋势变化;各树种自然饱和亏缺,临界饱和亏缺和自然需水程度值7月>5月>9月;ψssat值和ψstlp值随5月、7月、9月不断降低。5.根据植物水分利用参数变化规律,采用聚类分析方法,在不同季节将优势种水分利用参数聚类成型3-5个功能群。在同一功能群中,优势植物在不同生境间水分利用参数变化相似;不同季节,聚类在一起的植物种类不一致,说明植物随季节环境的变化自身水分适应策略也在发生变化,呈现多样性。水分参数日变化的多样性,季节变化的多样性和水分利用策略的变动避免了植物对水资源的竞争,对群落持续发育意义重大。更多还原

【Abstract】 The paper regards 30-year-old artificial Robinia pseudoacacia forests on shady slope in Yan’an Gonglu mountain as the research object, through determining water parameters(water potential,the water saturation deficiency ,the main PV water relation parameters)of 12 species under and out of Robinia pseudoacacia forests in different periods(initial growing period, vigorously growing period and the end-growing period),analysis on the characteristics of water utilization and balance mechanism, as well as divides into different functional groups by water utilization strategies of the dominant species, in order to clarify the relation between community stability and water-using diversity of various species.The main conclusions of this paper are:1.The water balance of dominant species in Robinia pseudoacacia forests show polymorphism. The water potential daily course of 12 dominant species under and out of forest are almost same in different stages, from 4:00 to21:00, water potential are "high - low - high " trendency, which have a negative correlation with the light intensity and temperature. The water potential values are different between plants in the same habitats, as well as water potential are altered with habitats changing, difference of water potential a day of same plant out of forest is greater than that under forest.2.Retention and resistance to dehydration of dominant species in Robinia pseudoacacia forests show polymorphism. In different stages, the average of natural water saturation deficit (N.W.S.D), critical water saturation deficit (C.W.S.D) and natural water requirement of 12 dominant species out of forest are higher than under forests. In the water saturation deficit values,there are remarkable difference among 12 species , and the change of water saturation deficit value of 12 species between different habitats is diversity.3. Water balance approaches of the different species in arid environment are varied. In different periods, in order to adapt to arid environment, the species reduce theψssatψstlp and RWCtlp, but increaseεmax for achieving the water balance. In the same habitat, the water parameters of 12 dominant species showed polymorphism. In different stages, the extent of water relation parameters value of same specie between different habitats was not the same.4. There are significant differences about water parameters of same species in different seasons, which show a big variety. Water parameters of 12 dominant species with seasonal variation show regularity. Water potential values from May to September is“high - low– high”trend. The value of N.W.S.D, C.W.S.D and natural water requirement are July> May> September, the order ofψssat value andψstlp value is May<July<September.5.In different seasons, the strategies of dominant species are divided into 3-5 types by cluster analysis in accordance with the change of Water parameters. In same group, the changes of water parameters between different habitats are similar. In different seasons,the species in one group are not all same ,which shows water adaptive strategies of same specie is also altered flowing season and environment changing, both the diversity of diurnal , seasonal changes of water parameters and the changes of water utilization strategies avoid the competition for water among different species ,which means a great deal to community development.更多还原