【作者】 赵志刚；

【导师】 徐建民；

【作者基本信息】 中国林业科学研究院 ， 林木遗传育种， 2011， 博士

【摘要】 格木（Erythrophleum fordii O.）是我国热带南亚热带地区的珍贵用材树种之一,且具有较高的药用价值和生态价值,由于长期的过度利用和毁林开荒等,其天然林资源已遭受严重破坏,被列为我国二级重点保护植物,并作为渐危种列入IUCN濒危物种红色名录。本研究全面调查了我国格木的天然分布、生境特征以及保护现状;重点揭示了典型格木种群（广西武鸣）的结构与动态以及海拔和人为干扰对格木种群以及天然林土壤化学性质的影响;探明了格木蛀梢害虫为害特点及其与环境因子间的关系;系统地收集了格木种质资源开展了种实和子代苗期表型变异研究,并运用SSR标记研究了其遗传多样性和遗传结构;进一步开展了种质资源迁地保存和利用研究。从种群生态学和种群遗传学两个方面较为系统地探讨了格木濒危现状、濒危机制以及可能的保护利用途径,为制定其保护和利用策略提供了科学依据。主要结果如下:1、我国格木天然分布范围主要在广西、广东、福建和台湾等地24°N以南地区,垂直分布多在海拔600m以下,集中生长于山体中下部。其面临的主要威胁来自于人类不合理开发利用、大面积毁林开荒种植农作物或发展其它树种等人为干扰,导致格木天然林及其生境破碎化十分严重。2、格木种群天然更新方式包括种子更新和萌芽更新,但种群扩散则依靠种子散布。格木土壤种子库属于聚集分布类型,其种群也呈聚集分布。研究以面积最大的样地Ⅱ（10000m2）为研究对象,通过编制种群静态生命表进行种群年龄结构与动态分析,结果显示,格木幼年个体数量较多,且死亡率高,种群下降快,中龄以后个体数量维持在较低水平,种群下降速率也基本稳定,但中间龄级死亡率低于成年阶段个体死亡率。总体来看随龄级增加生存率(S_i)下降,累计死亡率(F_i)上升,死亡密度(f_ti)和危险率(λ_ti)下降。因此,可以推断格木种群动态特征属于早期个体数量多,淘汰率高,进入中龄期竞争稳定死亡率趋稳,在进入成熟阶段个体竞争增加,死亡率也高于中龄期,因此,格木存活曲线属于Deevey存活曲线Ⅲ型。3、人为干扰对格木种群结构具有明显影响,其与海拔综合作用导致格木天然种群产生明显变化。不同海拔样地种群结构及其动态分析结果显示,随着海拔上升,样地内格木种群和土壤种子库的密度和频度均表现出先升高后略下降的趋势,而且土壤化学性质也表现出类似变化趋势,结果反映出格木在研究区域内垂直分布上限特征,也可以看出干扰对低海拔种群影响较中高海拔大。进一步采用种群数量变化动态指数进行不同海拔种群动态分析发现,上部海拔较高地点三个样地（Ⅰ、Ⅱ、Ⅲ）属于增长种群(V_pi>0,V′_pi>0),样地Ⅳ、Ⅴ属于衰退种群(V_pi<0,V′_pii<0)。4、格木蛀梢害虫是影响天然更新乃至种群维持以及人工幼林生长的主要限制因子之一。本研究重点调查、分析了格木种质资源保存林和萌芽更新萌条的蛀梢害虫为害状况,首次确定了格木蛀梢害虫为荔枝异形小卷蛾（Cryptophlebia ombrodelta L.）,其受害木在林分内呈聚集分布,为害率高达90%以上。研究初步总结了格木虫害的发生规律,但其发生的环境和气候条件尚需进一步研究。5、根据格木天然种群种实（8个种群）和子代苗期（6个种群）的表型变异分析结果可以看出,表型指标在种群间和种群内均存在丰富变异,种群间差异显著;荚果表型变异高于种子表型变异,即荚果表型受环境因子影响较大,子代苗期高生长变异大于地径;苗期表型性状与种子大小、千粒重性状间相关显著;与环境因子相关分析显示,格木荚果形态与经度显著负相关,种子表型中仅千粒重与纬度显著正相关,幼苗地径和高径比分别与年均温和海拔呈显著负相关;揭示出温度为格木天然种群水平分布和垂直分布的限制因素之一。6、应用5对SSR引物在9个种群中共检测到5个多态位点、34个等位基因,其中7个为特有基因,每个位点具1或2个公共基因。9个种群平均每个位点的A、Ae、Ho、He和I的均值分别为2.50、3.9、0.5313、0.5783和1.0088。整体而言,F_IS均值为0.0349,各种群大部分位点符合Hardy-Weinberg平衡。F_ST平均为0.1792,即17.92%的遗传变异存在于种群内,种群间的遗传分化较大,种群间基因流仅为1.1452。种群的遗传距离和地理距离之间的相关性进行Mantel检验,发现二者相关关系不显著（P>0.05）。7、迁地保护种质资源早期评价结果显示,格木种群内变异大于种群间变异,与分子水平检测结果一致。从保存林早期生长初步判断迁地保护效果较好,FJ01、GX04种群在两个试验地均表现较好,但仍需进行长期观测予以验证。从表型和SSR标记综合分析来看,格木迁地保护应重点扩大种群收集范围和数量,同时尽可能增加每个种群家系数量。更多还原

【Abstract】 Erythrophleum fordii O. is a valuable broad-leaved timber species with medical and ecological values in tropical and sub-tropical zones in south China. The natural forest of this species has been heavily destroyed due mostly to long-term over-exploitation and utilization, and alteration to croplands and fast-growing plantations. The species has thus been listed as of national second key protected plants, and been included in the IUCN Red List of Endangered Species as the endangered species. Here its natural geographical distribution, environmental properties for its suitable sites,and current status of its conservation were surveyed in south China; Its population structure and dynamics and their variation along altitude were studied in a large area of natural forests in Wuming County, Guangxi; Damage characteristics of a shoot borer in E. fordii plantations were investigated so as to follow the effects of this pest on conservation of this tree species; Germplasm resources were collected and phenotypic variation of fruite and seed, and their offspring seedlings were measured as well as genetic diversity and population genetic structure were estimated using SSR makers; Plantations were established using collected germplasm resources and their growth were investigated for purposes of ex situ conservation and breeding at two sites in Guangdong and Guangxi, respectively. Endangered status and mechanism and potential way for conservation of E. fordii were discussed at two aspects of population ecology and population genetics. The findings will provide evidences and basic data for making conservation and breeding strategy of this species. The main results were as follows:1. E. fordii was mainly distributed in Guangdong, Guangxi, Fujian and Taiwan Provinces in China, ranging from 24°N to south with altitude under 600m. The species grows mostly at the lower parts of mountains or hills, and human disturbances such as illegal logging, large-scale alteration into croplands and fast-growing plantations resulted in severe fragmentation of its natural forests and habitats. 2. Distributing pattern of seed and individual are cluster in E. fordii natural populations,population were regenerated by seeds and sprouts,but extended population were depend on seed spread. population age structure and dynamic were done by static life tab., seedlings and sapling was mass,but which have higher mortality rate,Survival numbers and mortality rates were descended in young and mature stages,following age increased, survival rate, mortality density,hazard rate were decline,but cumulative mortality rate ascend. so E. fordii population survive-shape curve remain with Deevey survive-shapeⅢtype.3. As surveyed on a slope of Wuming County, Guangxi, frequency and density of E. fordii in plots increased and then slightly decreased with the increasement of altitude. Similar to this was the way that soil chemical properties varied along with altitude. Population dynamics analysis showed that populations developed differently at all sorts of altitudes, populations at middle and upgrade altitude belonged to growing populations (plotⅠ,Ⅱ,Ⅲ;V_pi>0,V′_pi>0), while populations at low altitude to declining populations (plotⅣ,Ⅴ; V_pi<0,V′_pii<0).4. Shoot borer attack is one of main factors that poorly influence natural regeneration and even population maintanance, and survival and early growth performances of plantations of this species. It occurs very often in natural forests as well as plantations of E. fordii. In the present studies, the shoot borer was identified as Cryptophlebia ombrodelta L. at the first time. As investigated in germplasm resources conservation pools and coppice plantations of this species, the pest could harm above 90% of buds and tender branchs, even petiole at tree top. The damaged trees were distributed in cluster pattern within plots. The occurrence of insect damage was preliminarily concluded, and relationship between insect attack and site condition need be further studied.5. Phenotypic variation of seeds and pods in 8 natural populations,and seed germination and seedling growth of progenies from 6 natural populations were analyzed,the results showed that there were abundant variations of phenotypic traits of seeds, pods and seedlings within and among populations, and significant differences among populations. Variation of pod traits among populations was higher than that of seeds, variation of seedling height among populations was higher than that of stem collar diameter, and seedling performance was remarkably correlated with seed size and seed mass. Pod morphology was in significantly negative correlation to longitude, seed mass positive to latitude, and seedling collar diameter and height negative to mean annual rainfall and altitude, respectively. These indicated that temperature was the main factor that restricted the natural distribution of E. fordii.6. Genetic diversity and structure of E. fordii were analyzed using SSR markers in nine populations. Five polymorphic loci were obtained with totally 34 alleles,among which seven were private alleles, and one or two common alleles per locus. The mean number of alleles per locus（A）, the mean number of efficient alleles per locus（Ae）, the expected and observed heterozygosities,Shannon index（I） were 3.9, 2.50, 0.5313, 0.5783 and 1.0088, respectively. F_IS was on average 0.0349, most loci were on Hardy-Weinberg equilibrium in the nine populations. F_ST was 0.1792, which was indicated that there existed 17.92% genetic variation among populations. Gene flow between populations （Nm） was 1.1452, and significant differentiation occurred among populations. And correlation between genetical and geographical distance was not significant by Mantel test （P>0.05）.7. Two plantations were established for ex situ conservation and utilization of germplasm resources of E. fordii in Guangdong and Guangxi, respectively. Earlier evaluation were conducted according to their growth performance of height and collar diameter, and damage rate by shoot borer. There were more variation within than among populations,in accordance to results at DNA level. Through two-year observations, the gerplasm resource pool were preliminarily proved to be well established, and progenies from two populations grew better, which should be further proved. And from the findings of phenotypic and SSR variations it was indicated that more populations and as many families as possible in each population should be collected for ex situ conservation of germplasm resources of this species in the future.更多还原