【作者】 刘方炎；

【导师】 张志翔；

【作者基本信息】 北京林业大学 ， 野生动植物保护与利用， 2011， 博士

【摘要】 金沙江干热河谷地区属于典型的生态环境脆弱区。该区域自然条件恶劣,植被退化现象尤为严重。滇榄仁群落和锥连栎群落是金沙江干热河谷(元谋段)2种极为重要的天然植被类型。在人为干扰持续存在甚至不断加强的背景下,研究群落内幼苗建成及其对环境因子的响应机制,对天然植被的抚育管理以及该地区的生态恢复均具有重要的意义。本研究采用野外样地调查、跟踪观测以及室内控制实验,系统研究了滇榄仁群落特征、植株开花生物学特征、种子生物学及其萌发特性、土壤种子库与幼苗更新动态以及主要环境因子对幼苗早期生长的影响等。同时,对锥连栎群落学特征、种子生物学与萌发特征以及幼苗早期生长对主要环境因子的响应特征等进行了探讨,明确界定了滇榄仁和锥连栎种子萌发和幼苗早期生长适宜的环境条件,并在此基础上分析了滇榄仁和锥连栎幼苗在群落中的建成机制及其对环境条件的生态适应性。研究得到如下结果。(1)金沙江干热河谷(元谋段)残存的滇榄仁群落和锥连栎群落中植物种类组成均较为简单。前者共发现32种植物,隶属于16科28属；后者共发现68种植物,隶属于35科60属。2种群落的物种多样性程度均较为低下,以禾本科、蝶形花科、唇形科等植物居多。(2)滇榄仁花朵开放时,柱头先伸长和膨大,而后,雄蕊开始外展。单个花朵开放期,即从柱头伸出花蕾到花药开始枯黄,约为10-15 d。在花序水平上,基部花比顶部花先开放。滇榄仁可能同时存在着风媒传粉和虫媒传粉两种形式,繁育系统以异交为主,部分自交亲和,需要传粉者,且同花序、异花序花朵均能相互授粉,但异花序授粉的果实饱满率显著高于同花序授粉果实。(3)滇榄仁和锥连栎种子萌发均对水分条件极为敏感,其萌发进程在一定程度上受到了水分条件限制。同时,滇榄仁种子在室温(25℃)和20℃-30℃变温时萌发效果最好,15℃时受到强烈抑制；锥连栎种子在20℃-30℃变温时萌发效果最好,35℃时受到一定程度的抑制。2种植物种子均不具有休眠特性,种子落地后遇到适宜条件即能萌发。但储藏(小于1年)有利于滇榄仁种子萌发,而不利于锥连栎种子萌发。曝晒可以致使锥连栎萌发率出现显著下降。(4)滇榄仁种子库有植冠种子库和土壤种子库两种形式。其中,种子在冠层上存在的时间可以超过1年,其脱落过程与风力可能存在着正相关关系,与降雨量和空气相对湿度存在着负相关关系。滇榄仁种子以风力传播为主,其种子散布距离较远(>11.5m)(5)滇榄仁幼苗更新均发生在雨季,旱季不更新。能否顺利度过幼苗刚萌发后的这段时间是林下幼苗成功更新的关键。群落内,天然更新幼苗具有明显的聚集分布特征,更新幼苗多集中在车桑子灌丛下或滇榄仁成年植株基部等环境较好的地方。(6)水分条件对滇榄仁和锥连栎幼苗早期生长过程中植株形态、叶片特征以及生物量分配等均具有显著的影响。2种植物幼苗对水分胁迫均具有一定的适应能力,但滇榄仁对水分条件的适应幅度相对较窄,而锥连栎对水分的适应幅度较宽,它能同时在极干旱和较湿润环境下存活、生长,生态适应性极强。(7)扭黄茅的竞争对滇榄仁幼苗早期生长过程具有显著影响。群落中滇榄仁幼苗的萌发时间以及周围扭黄茅的数量在幼苗种群幸存(成活)与生长状况中扮演了一个极为重要的角色,提前定居以及周围扭黄茅数量较少时,滇榄仁幼苗具有极大的生存优势。生境异质性是影响锥连栎幼苗成功定居的重要因子之一,落叶堆积洼地和落叶堆积平地是锥连栎林下幼苗定居较为理想的微生境。元谋干热河谷区滇榄仁群落和锥连栎群落中均能产生相对较多的幼苗,但幼树均极为罕见。能否顺利度过幼苗刚萌发后的这段生长时间是林下幼苗成功更新的关键,因此,加强群落内植物多样性的保育,使之形成良好的林下环境有利于幼苗早期生长。同时,在人工抚育管理和植被恢复中,为幼苗早期生长营造一个能够集水、保水的环境条件极为重要,如覆盖枯落物和薄膜以及深挖塘等。更多还原

【Abstract】 Dry-hot valleys of Jinsha River are typical ecological fragile areas in southwest of China. There are poor natural conditions and seriously vegetation degradation in these areas. Communities of Teminalia franchetii and Quercus franchetii are two very important natural vegetation types in Yuanmou county segment of Jinshajiang dry-hot valley. In the context of sustained or even strengthened human disturbance, there is great significance for cultivation and management of natural vegetation and ecological restoration in the region, which study seedling establishment of the community and its response mechanism to environmental factors. In this study, field sample investigation, follow-up observation and indoor control experiments were employed, community characteristics, flowering biological characteristics, seed biology and germination characteristics, soil seed band and seedling dynamics and the main impact factors of seedling early growth about T. franchetii were systematically studied. At the same time, we researched community characteristics, seed biology and germination characteristics, and characteristics of seedling early growth response of the main environmental factors about Q. franchetii. The suitable environmental conditions for seed germination and seedling early growth of T. franchetii and Q. franchetii were clearly determined, and seedling establishment mechanism and its ecological adaptation to environments of them were analyzed. Research results are as follows.Ⅰ. There are extremely simple species composition in both T. franchetii and Q. franchetii remaining communities of Yuanmou dry-hot valley.32 kinds of plants were found in the former, which belong to 16 families and 28 genera, and 68 kinds of plants were found in the latter, which belong to 35 families and 60 genera. Species diversity of two kinds of communities was relatively low, and the main species of them belong to Poaceae, Papilionaceae and Labiatae families.Ⅱ. When T. franchetii flowers open, their stigmas spread and enlarge first, then stamens begin expand. Single flowers of T. franchetii approximately have 10-15 days flowering period, which shows the period from the stigma spreading out of buds to anthers fading. There may be wind pollination and insect pollionation of two forms in T. franchetii, and its breeding system was dominated by outcrossing, part of them was self-compatible, requiring pollinators, and flowers in the same inflorescence or different inflorescence can pollinate each other. However, different inflorescence pollinated seed yield was significantly higher than the same inflorescence pollination.Ⅲ. Both T. franchetii and Q. franchetii seeds germination are extremely sensitive to water conditions, and their germination process to some extent was limited by the moisture conditions. At the same time, there is the best germination for T. franchetii seeds at room temperature (25℃) and 20-30℃day-and-night changed temperature, and its germination was strongly inhabited at 15℃temperature. There is the best germination for Q. franchetii seeds at 20-30℃day-and-night changed temperature, and its germination to some extent was limited at 35℃.2 kinds of plant seeds have no dormancy; they may germinate in the suitable conditions when they fall to the ground. Storage (less than 1 year) is conducive to T. franchetii seeds germination, is not conducive to Q. franchetii seeds germination. Exposure in the sun can cause Q. franchetii seeds germination rate decreased significantly.Ⅳ. T. franchetii seed banks include canopy seed bank and soil seed bank of two kinds of forms. Retention time of seeds in the canopy was more than 1 year, and there may be a positive correlation between seed shedding and wind power, and there may be a negative correlation between seed shedding and rainfall and relative humidity of the air. T. franchetii seeds spread mainly by wind power, and the distance of seed dispersal were very far (more than 11.5 m).Ⅴ. T. franchetii seedling regeneration occurred in the rainy season, there is no seedling regeneration in the dry season. Seedlings can survive the period just after germination is the key to forest seedlings successfully regeneration. In communities, distribution of the natural regeneration seedlings has obviously aggregation characteristics. The seedlings are more concentrated under Dodonaea viscosa shrubs or near the basal of T. franchetii adult plants and other good environments.Ⅵ. Water conditions have a significant impact on plant morphologic characteristics, leaf characteristics and biomass allocation during early growth of both T. franchetii and Q. franchetii seedlings. Two kinds of seedlings showed some ability to adapt water stress, but T. franchetii seedlings showed a relatively narrow range of water condition than Q. franchetii seedlings. And Q. franchetii seedlings can survive or grow simultaneously in a very dry and more humid environment, and has a strong ecological adaptability.Ⅶ. Competition of Heteropogon contortus has a significant impact on the early growth process of T. franchetii seedlings. Seedling germination time and the number of surrounding H. contortus populations play an extremely important role in T. franchetii seedlings survive and growth. When T. franchetii seedling establish before H. contortus or there are small number of H. contortus populations, T. franchetii seedling have great survival advantage. Habitat heterogeneity is one of important factors which affect Q. franchetii seedlings successful establishment in communities, and low land covered by litter (LLCL) and flat ground covered by litter (FGCL) were better micro-habitats for Q. franchetii seedlings growth.Relatively more seedlings can be found in both T. franchetii community and Q. franchetii community in Yuanmou dry-hot valley, but saplings are rare. Seedlings can get through the period after seed just germination is the key to forest seedlings successfully regeneration. Therefore, it is useful for early growth of forest seedling to strengthen the conservation of plant diversity within the community, and make it a good environment. At the same time, in the artificial cultivation and management and vegetation restoration, it is very important to create a catchment, water retention environmental conditions for the early growth of seedling, such as litter or film cover habitas and deep dig ponds to breed.更多还原