异质景观中西南桦天然种群的空间遗传结构与过程解析

发布时间：2018-07-28 10:11

【摘要】：探究生境影响下的植物种群遗传变异,换言之,从生境影响到遗传变异是如何过渡的,是景观遗传学研究的主要内容:从发现空间格局入手,分析格局与环境特征相关性,探究两者之间的过程变化。研究过程中需要关注种群数量动态和空间分布格局、繁殖体的扩散样式和局限性、遗传变异时空格局以及生境异质性影响等方面。这方面的研究已经成为热点。本研究即以广西靖西县地州乡的一个土石山生态交错区的8个西南桦天然种群为研究对象,运用生态学、种群遗传学的研究手段,力求揭示异质景观中生境因子的空间分布特征、西南桦种群数量动态和空间分布格局、种子和花粉散布特征、西南桦种群的空间遗传结构及其相互联系,为景观遗传学研究提供一个案例,亦为西南桦遗传改良、种子园营建、天然林经营管理以及人工林的健康发展提供理论依据。主要结果如下:(1)表层土壤含水量、土层厚度和枯落物厚度3个生境因子均表现为在小尺度上存在空间变异格局。土层厚度、表层土壤含水量和枯落物厚度分别在0~14m、0~17m和0~20m尺度上存在正的自相关性,在其他尺度上不具空间自相关性或者负自相关性;所有生境因子之间均存在关联性,表层土壤含水量与土层厚度、落物厚度分别在7~18m和0~3m尺度上间存在正相关,其它尺度上不具关联性或呈负相关性。(2)西南桦年龄结构和动态因斑块而异。总体来看各斑块都有着随龄级的增加,其个体数所占比例逐渐减小的趋势。依据幼龄(龄级1~2)、中龄(龄级3~7)、老龄(龄级8~12)3个组的比例,可将隆减、院城、小学、远处4个斑块西南桦种群归为增长型种群,兵营西南桦种群为稳定型种群,兵营对面、弄股山、土山3个西南桦种群归为衰退型种群。静态生命表分析显示随着龄级的增加,所有斑块西南桦种群死亡率和消失率总体呈现先减小后增加再减小的趋势,在龄级7或者龄级9达到最大值。绘制不同斑块西南桦种群的存活曲线发现隆减和远处为Deevey-Ⅲ型;院城和小学为Deevey-Ⅱ型;兵营、兵营对面、弄股山、土山种群存活曲线呈Deevey-Ⅰ型。(3)绝大部分斑块的西南桦种群不同发育阶段个体均在小尺度上呈聚集分布,具体为:整体上隆减、院城、小学、兵营、兵营对面、远处、土山等7个种群分别在0~11m、0~20m、0~16m、0~15m、4~8m、0~1m、0~7m呈聚集分布,弄股山在全尺度上以随机分布为主;相较幼树和成年树阶段,幼苗阶段在相对较小尺度上呈聚集分布。西南桦种群的空间分布格局与生境因子的空间变异格局均在小尺度上呈现关联性,具体为:与表层土壤含水量和土层厚度分别在0~2m和0~5m尺度上呈正相关,与枯落物厚度在3~17m尺度上呈现负相关;相较幼树和成年树阶段,幼苗阶段空间分布格局在小尺度上与生境因子空间变异格局具有较强的相关性。(4)林分水平上西南桦种子散布的初始期、高峰期、消退期分别历时11天、32天和40天,而个体水平上则为9天、25天和26天;高峰期内林分和个体水平的散种量分别占其总量的83.1%和68.7%,而且白天的种子雨密度高于夜间;西南桦个体白天种子雨密度最大的时段为12:00~16:00,与此时段内风速较高有关。在个体水平上,距离母树0~30m范围内散落的种子占总量的79.6%;而在林分水平上,距离林缘0~45m范围内集中了总散种量的81.2%。西南桦种子散布具有方向性与散种期内的盛行风向有关,种子雨密度与风速亦呈极显著正相关。(5)景观水平上,西南桦花粉的散布最近距离为1.6m,发生在兵营斑西南桦个体间;最远距离为2098.9m,发生在院城斑块和弄股山斑块的西南桦个体间。在小于200m的范围内交配事件最为频繁。与斑块外相比,西南桦个体接受来自本斑块的花粉比例相对较高。总体来看,来自院城斑块的东北方向是研究区域内花粉流的主要来源方向。(6)大部分斑块的西南桦种群具有较强的空间遗传结构,不同斑块尺度不同。具体为:隆减、院城、小学、兵营、兵营对面西南桦种群分别在0~10m、0~70m、0~70m、0~40m、0~40m尺度上具有较强的空间遗传结构,弄谷山、远处、土山由于个体数较少,其种群的遗传变异在全尺度上主要表现为不存在空间自相关性。相较幼树、成年树阶段,大部分斑块的幼苗阶段在较小尺度上具有空间遗传结构。研究区域内,不同斑块西南桦种群小尺度的空间遗传结构是异质微生境、花粉和种子散布规律、种群的聚集分布以及人为活动干扰共同作用的结果。
[Abstract]:To explore the genetic variation of plant population under the influence of habitat, in other words, how is the transition from habitat impact to genetic variation, is the main content of landscape genetics research: from the discovery of spatial pattern, the correlation between the pattern and the environmental characteristics is analyzed, and the process changes between the two are explored. The research process needs to pay attention to the population dynamics and space. The distribution pattern, the pattern and limitation of the propagating body, the spatial and temporal pattern of the genetic variation and the influence of the habitat heterogeneity have become a hot spot. This study is based on the ecology and population genetics of 8 natural populations of birch in a soil stone mountain ecotone, Jingxi County, Guangxi. The study means to reveal the spatial distribution characteristics of the habitat factors in the heterogeneous landscape, the population dynamics and spatial distribution pattern of the birch population, the characteristics of seed and pollen dispersal, the spatial genetic structure and the interrelation of the birch population, and provide a case for the study of landscape genetics, and also for the genetic improvement of the Betula alba, the construction of the seed orchard and the sky. The main results are as follows: (1) the 3 habitat factors of surface soil water, soil thickness and litter thickness all show spatial variation pattern on small scale. Soil thickness, surface soil moisture content and litter thickness are on 0~14m, 0~17m and 0~20m scales, respectively. There is a positive autocorrelation and no spatial autocorrelation or negative autocorrelation on other scales; there are correlations among all habitat factors. There is a positive correlation between the water content of the surface soil and the thickness of soil layer and the thickness of the falling objects on the 7~18m and 0~3m scales respectively, and there is no correlation or negative correlation on the other scales. (2) the age of Betula alba The structure and dynamics vary with the plaque. In general, the proportion of individual patches is gradually decreasing. According to the proportion of young (age class 1~2), middle age (age class 3~7) and aging (age grade 8~12), the proportion of 3 groups of aged (age class) can be reduced, the City, primary school, and the distant 4 plaques of Betula Alba belong to the growth population, and the birch in the barracks The population is a stable population, and the population of 3 birch populations of Nong Shan and Tu Shan is classified as a decline population. The static life table analysis shows that with the increase of age, the mortality and disappearance of the birch population in all plaques increases first and then decreases, and reaches the maximum at the age level of 7 or the age grade 9. The survival curve of the population of Betula Alba was found to be Deevey- III in the distance and in the distance, while the hospital city and the primary school were Deevey- II; the barracks, opposite to the barracks, the Dun Shan mountain, the survival curve of the soil mountain population were Deevey- I. (3) the individuals of the birch population at different stages of the vast majority of plaques were aggregated on the small scale, specifically the overall uplift and reduction. 7 populations, such as city, primary school, barracks, barracks, distant, and earth mountain, were distributed in 0~11m, 0~20m, 0~16m, 0~15m, 4~8m, 0~1m, 0~7m, and the distribution distribution of Nong Shan mountain was mainly distributed on the whole scale; compared with the young and adult trees, the seedling stage was relatively small on the scale. The spatial distribution pattern and habitat cause of the birch population The spatial variation patterns of the subgroups were all related on the small scale, which was positively correlated with the soil moisture content and the thickness of soil layer on the 0~2m and 0~5m scales respectively, and the thickness of the litter was negatively correlated with the 3~17m scale, and the spatial distribution pattern of the seedling stage was on the small scale with the habitat factor space. The variation pattern has strong correlation. (4) the initial period of seed dispersal, the peak period and the decline period of the birch seed in the stand level are 11 days, 32 days and 40 days respectively, while the individual level is 9 days, 25 days and 26 days, and the amount of the stand and individual level in the peak period is 83.1% and 68.7% respectively, and the seed rain density in the daytime is higher than that of the individual. At night, the maximum density of daytime seed rain was 12:00~16:00, which was related to the higher wind speed within this period. At the individual level, the seeds scattered in the range of 0~30m from the mother tree accounted for 79.6% of the total. At the stand level, the dispersal of the seed dispersal of the total scattered species of 81.2%. in the range of 0~45m was directional. In relation to the prevailing wind direction, the seed rain density is also positively correlated with the wind speed. (5) at the landscape level, the dispersal of the birch pollen is 1.6m, which occurs among the birch individuals of the barracks, and the farthest distance is 2098.9m. Compared with the patch, the percentage of pollen from the plaque was relatively high compared with the plaque. In general, the northeast direction from the hospital plaque was the main source of the pollen flow in the study area. (6) the population of Betula alba in most plaques had a strong spatial genetic structure, and different patch scales were different. The population of Betula Alba has strong spatial genetic structure on the scale of 0~10m, 0~70m, 0~70m, 0~40m, and 0~40m on the scale of long and subtract. The genetic variation of the population is mainly shown as no spatial autocorrelation on the whole scale. The seedling stage of most plaques has spatial genetic structure on a smaller scale. In the study area, the spatial genetic structure of the small scale of birch population in different patches is heterogeneous microhabitat, pollen and seed dispersal law, population aggregation distribution and human activity interference are used together.
【学位授予单位】：中国林业科学研究院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S792.15

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