【摘要】：探究生境影響下的植物種群遺傳變異,換言之,從生境影響到遺傳變異是如何過(guò)渡的,是景觀遺傳學(xué)研究的主要內(nèi)容:從發(fā)現(xiàn)空間格局入手,分析格局與環(huán)境特征相關(guān)性,探究?jī)烧咧g的過(guò)程變化。研究過(guò)程中需要關(guān)注種群數(shù)量動(dòng)態(tài)和空間分布格局、繁殖體的擴(kuò)散樣式和局限性、遺傳變異時(shí)空格局以及生境異質(zhì)性影響等方面。這方面的研究已經(jīng)成為熱點(diǎn)。本研究即以廣西靖西縣地州鄉(xiāng)的一個(gè)土石山生態(tài)交錯(cuò)區(qū)的8個(gè)西南樺天然種群為研究對(duì)象,運(yùn)用生態(tài)學(xué)、種群遺傳學(xué)的研究手段,力求揭示異質(zhì)景觀中生境因子的空間分布特征、西南樺種群數(shù)量動(dòng)態(tài)和空間分布格局、種子和花粉散布特征、西南樺種群的空間遺傳結(jié)構(gòu)及其相互聯(lián)系,為景觀遺傳學(xué)研究提供一個(gè)案例,亦為西南樺遺傳改良、種子園營(yíng)建、天然林經(jīng)營(yíng)管理以及人工林的健康發(fā)展提供理論依據(jù)。主要結(jié)果如下:(1)表層土壤含水量、土層厚度和枯落物厚度3個(gè)生境因子均表現(xiàn)為在小尺度上存在空間變異格局。土層厚度、表層土壤含水量和枯落物厚度分別在0~14m、0~17m和0~20m尺度上存在正的自相關(guān)性,在其他尺度上不具空間自相關(guān)性或者負(fù)自相關(guān)性;所有生境因子之間均存在關(guān)聯(lián)性,表層土壤含水量與土層厚度、落物厚度分別在7~18m和0~3m尺度上間存在正相關(guān),其它尺度上不具關(guān)聯(lián)性或呈負(fù)相關(guān)性。(2)西南樺年齡結(jié)構(gòu)和動(dòng)態(tài)因斑塊而異。總體來(lái)看各斑塊都有著隨齡級(jí)的增加,其個(gè)體數(shù)所占比例逐漸減小的趨勢(shì)。依據(jù)幼齡(齡級(jí)1~2)、中齡(齡級(jí)3~7)、老齡(齡級(jí)8~12)3個(gè)組的比例,可將隆減、院城、小學(xué)、遠(yuǎn)處4個(gè)斑塊西南樺種群歸為增長(zhǎng)型種群,兵營(yíng)西南樺種群為穩(wěn)定型種群,兵營(yíng)對(duì)面、弄股山、土山3個(gè)西南樺種群歸為衰退型種群。靜態(tài)生命表分析顯示隨著齡級(jí)的增加,所有斑塊西南樺種群死亡率和消失率總體呈現(xiàn)先減小后增加再減小的趨勢(shì),在齡級(jí)7或者齡級(jí)9達(dá)到最大值。繪制不同斑塊西南樺種群的存活曲線發(fā)現(xiàn)隆減和遠(yuǎn)處為Deevey-Ⅲ型;院城和小學(xué)為Deevey-Ⅱ型;兵營(yíng)、兵營(yíng)對(duì)面、弄股山、土山種群存活曲線呈Deevey-Ⅰ型。(3)絕大部分斑塊的西南樺種群不同發(fā)育階段個(gè)體均在小尺度上呈聚集分布,具體為:整體上隆減、院城、小學(xué)、兵營(yíng)、兵營(yíng)對(duì)面、遠(yuǎn)處、土山等7個(gè)種群分別在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隨機(jī)分布為主;相較幼樹(shù)和成年樹(shù)階段,幼苗階段在相對(duì)較小尺度上呈聚集分布。西南樺種群的空間分布格局與生境因子的空間變異格局均在小尺度上呈現(xiàn)關(guān)聯(lián)性,具體為:與表層土壤含水量和土層厚度分別在0~2m和0~5m尺度上呈正相關(guān),與枯落物厚度在3~17m尺度上呈現(xiàn)負(fù)相關(guān);相較幼樹(shù)和成年樹(shù)階段,幼苗階段空間分布格局在小尺度上與生境因子空間變異格局具有較強(qiáng)的相關(guān)性。(4)林分水平上西南樺種子散布的初始期、高峰期、消退期分別歷時(shí)11天、32天和40天,而個(gè)體水平上則為9天、25天和26天;高峰期內(nèi)林分和個(gè)體水平的散種量分別占其總量的83.1%和68.7%,而且白天的種子雨密度高于夜間;西南樺個(gè)體白天種子雨密度最大的時(shí)段為12:00~16:00,與此時(shí)段內(nèi)風(fēng)速較高有關(guān)。在個(gè)體水平上,距離母樹(shù)0~30m范圍內(nèi)散落的種子占總量的79.6%;而在林分水平上,距離林緣0~45m范圍內(nèi)集中了總散種量的81.2%。西南樺種子散布具有方向性與散種期內(nèi)的盛行風(fēng)向有關(guān),種子雨密度與風(fēng)速亦呈極顯著正相關(guān)。(5)景觀水平上,西南樺花粉的散布最近距離為1.6m,發(fā)生在兵營(yíng)斑西南樺個(gè)體間;最遠(yuǎn)距離為2098.9m,發(fā)生在院城斑塊和弄股山斑塊的西南樺個(gè)體間。在小于200m的范圍內(nèi)交配事件最為頻繁。與斑塊外相比,西南樺個(gè)體接受來(lái)自本斑塊的花粉比例相對(duì)較高�？傮w來(lái)看,來(lái)自院城斑塊的東北方向是研究區(qū)域內(nèi)花粉流的主要來(lái)源方向。(6)大部分斑塊的西南樺種群具有較強(qiáng)的空間遺傳結(jié)構(gòu),不同斑塊尺度不同。具體為:隆減、院城、小學(xué)、兵營(yíng)、兵營(yíng)對(duì)面西南樺種群分別在0~10m、0~70m、0~70m、0~40m、0~40m尺度上具有較強(qiáng)的空間遺傳結(jié)構(gòu),弄谷山、遠(yuǎn)處、土山由于個(gè)體數(shù)較少,其種群的遺傳變異在全尺度上主要表現(xiàn)為不存在空間自相關(guān)性。相較幼樹(shù)、成年樹(shù)階段,大部分斑塊的幼苗階段在較小尺度上具有空間遺傳結(jié)構(gòu)。研究區(qū)域內(nèi),不同斑塊西南樺種群小尺度的空間遺傳結(jié)構(gòu)是異質(zhì)微生境、花粉和種子散布規(guī)律、種群的聚集分布以及人為活動(dòng)干擾共同作用的結(jié)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.
【學(xué)位授予單位】：中國(guó)林業(yè)科學(xué)研究院
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：S792.15

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