【作者】 宋于洋；

【导师】 张文辉；

【作者基本信息】 西北农林科技大学 ， 森林培育， 2011， 博士

【摘要】 以古尔班通古特沙漠不同区域梭梭种群为研究对象,通过样地调查和定点监测,研究了土壤种子库分布和幼苗定居规律；生殖力、生殖值和生殖分配特征；建立了年龄方程、分析了种群动态、生存策略、空间分布格局和动态特征；探讨了梭梭群落盖度、丰富度对沙丘稳定性的影响,为梭梭种群的保护利用提供了依据。主要研究结果如下：1.梭梭土壤种子库的分布格局：梭梭种子集中分布在Ocm-1cm土层,随着土层深度的增加,土壤种子密度急剧减少。种子库空间结构分析表明,不同样地的空间格局强度及空间结构组成等均有显著差异,除部分样地外,均表现出空间自相关性,空间自相关范围在5-44.4m之间：梭梭种子库的空间格局各向异性特征主要体现在0°(或90。)与45°(或135°)上；各样地在5m或更小的尺度上能很好表现出空间异质性。梭梭土壤种子库大小与群落盖度、土壤含水量等因子存在显著相关性。2.梭梭幼苗定居规律：2-4年和5-6年生梭梭幼苗多出现在成年树周围、迎风坡低洼处或丘间的裂缝处；分布最多的是迎风坡,其次是丘间、背风坡和坡顶；影响梭梭定居的环境因子中,地形和群落盖度影响显著,其次是土壤含水量、含盐量；梭梭种群定居的适宜条件是坡度适宜、盖度较高、土壤条件较好的区域。3.梭梭种群的波动特征：梭梭种群的存活曲线基本接近于DeeveyⅢ型,死亡率前期较高,后期相对较小,出现了2-4次死亡高峰期。不同生境下的谱分析推绎显示,小尺度变化较大,大尺度变化逐渐趋于平稳,表明古尔班通古特沙漠在相对较好的环境条件下,梭梭种群的周期性波动可在较小的取样面积实现稳定(即样地面积为8000-9200m2),在相对较差的环境条件下需要较大的取样面积才能实现稳定(即样地面积为11600-14000 m2)。因此,在进行谱分析时,应针对不同的环境条件确定取样面积,才能分析最佳尺度的周期性波动。4.种群分布格局：L(r)函数显示梭梭种群格局倾向于聚集分布,且集中分布在0-25m尺度范围内,而g(r)函数分析在小于5m的尺度上呈聚集分布；梭梭在不同发育阶段过程中,L(r)和g(r)函数基本上都显示由幼苗、幼树的聚集分布变为成年树的随机分布,甚至在某些尺度上变为均匀分布,同时幼苗幼树向成年树过渡过程中,梭梭的聚集强度呈逐渐减弱趋势。在关联性分析中,L(r)夕函数中正关联维持的尺度范围较g(r)函数大。L(r)函数分析幼苗与幼树、成年树在0-18m尺度内呈现正关联,g(r)函数在0-5m范围内表现为正关联,而幼树与成年树在0-8m尺度内多呈负关联。另外,梭梭种群分布格局的强度在不同地形也存在差异。5.多尺度格局的交替波动特征：应用Mexh和Morl生态用小波,对不同地点、不同沙丘类型梭梭分布格局的波动特征及其维持机制进行了分析。结果表明：Mexh、Morl生态用小波能够识别平行状沙丘、梁窝状沙丘和树杈状沙丘的主要波动周期分别为165-180m、100-110m和70-80m；除了主要波动周期外,Morl生态用小波还显示出不同尺度(等级)格局交替循环现象。因此可以根据波动周期预测一定区域内梭梭分布格局的趋势。梭梭空间分布格局的变化在不同尺度上影响因素不同。在大尺度上主要受沙丘类型的影响；在中尺度上主要受坡向、坡面的长度等因素影响；在小尺度上主要是土壤含水量和含盐量等因素影响。6.梭梭种群生殖力：生殖力(bx)随着龄级的增加呈现逐渐增加的趋势,从低龄组到高龄组,呈现出低→高→低的趋势。以种子为基础计算的生殖力参数：净增值率Ro=734.78-2786.2,内禀增长率rm=0.576-1.166,种群世代平均周期T=6.8-11.457年,加倍时间t=0.59-1.203年,理论上种群数量在一年内就可加倍。如果以1年生幼苗为基础的加倍时间t=-215817-1789364,种群翻倍的时间非常缓慢。梭梭种群在土质类型中世代周期最长,适合度最大；生殖值Vx、剩余生殖值RRV以及整个生活史总生殖值TRV的各累积值与r值变化一致。土质和沙质类型梭梭属于K对策者；砾石类型表现出r对策者的特征；在极端胁迫的盐土类型中则表现为植物生活史型C的特征。7.梭梭的生殖分配：在砾石、土质、盐土和沙质四种土壤类型下梭梭生殖分配在0.64%-1.5%之间。开花枝率和结果枝率的峰值均出现在0.5-2.0cm短枝上。生殖分配具有显著的等级差异性,四种类型下的生殖分配和同化枝生物量之间存在线性或多项式的关系。生殖分配和生殖输出具有大小依赖性。同其它三种类型相比,条件恶劣的砾石类型梭梭的生殖分配最大。总体上,梭梭在不同土壤类型中进化稳定性是不同的。8.梭梭的年轮特征和年龄：梭梭每年形成的年轮数量在2.9-5.9个之间,年轮每轮宽度在0.154-0.455mm之间。盐土类型加权平均年龄为6.81年,最大年龄为25年；砾石类型加权平均年龄为8.21年,最大的年龄为38年；土质类型加权平均年龄为14.59年,最大年龄是55年；沙质类型加权平均年龄为10.86年,最大的年龄为40年。梭梭在每年生长季均形成多轮,我们认为多轮更是梭梭的自然特征。过渡径宽轮处的晚材由22-35层细胞的薄壁组织构成,早材由4-15层细胞的薄壁组织构成。9.梭梭群落盖度、丰富度与沙丘稳定性：大尺度上,4-6月份降水量决定了梭梭群落盖度的分布；小尺度上,梭梭群落盖度受地形、土壤含水量和盐分等因子综合影响；梭梭群落丰富度在大小尺度上均由土壤含水量和全盐含量等因素共同决定。不同地形相对风蚀率有显著差异：坡顶>缓坡>丘间。梭梭群落盖度、丰富度与风蚀量相关程度因地形而异,缓坡和坡顶表现为显著相关,丘间无相关性。更多还原

【Abstract】 In this paper, H.ammodendron population in the Gurbantunggut Desert was taken as the research object by plot investigation and anchor point measure in the different regions. Soil seeds bank, seedling establishment, spatial pattern and dynamic characteristic were studied; establishing age function, opening out the fecundity, reproductive value and RA; discussing effect of coverage and species richness of community to dune stability, in order to to provide theoretical bases for protecting and utilizing H.ammodendron population. The main results were as follows:(1) The pattern of soil seeds bank in H.ammodendron:On the vertical distributions, seeds of H.ammodendron were concentrated distribution in Ocm-lcm soil layer. Soil seed density decreased rapidly with soil depth. Analysis of isotropic spatial structure of soil seeds bank showed that there were significant differences in spatial pattern strength and spatial structure composition among different plots, besides the partial plot, all other plots showed spatial autocorrelation, the scale of spatial autocorrelation were between 5 and 44.449m. The anisotropy of spatial pattern of H.ammodendron seeds bank mainly reflected on 0°(or 90°)and 45°(orl35°). The spatial heterogeneity of each plot can be showed quite well in 5m or a smaller interval distance. There was significantly correlation between seeds bank and vegetation coverage, soil water content etc.(2) Seedlings establishment:Seedlings of H.ammodendron within 2 to 4 years old and 5 to 6 years old appeared around adult, the downfold of the windard slope or crack of interdune. The site with the largest number of seedling was windward slope, next came interdune, lee slope and crest. Terrain and coverage occupied a dominant position in influencing factors of establishment. Next to soil moisture, soil salt content. The suitable region of establishment was appropriate slope, highter coverage and better soil condition.(3) The dynamic characteristics of H. ammodendron:the survival curve of H. ammodendron populations tended to be the type of Deevey-III, the mortality rate of H. ammodendron was high at early stage and low at late stage, there existed 2-4 death peak phases in the population life process. Upscaling process of spectral in different habitat shows that the change in small scale was more prominent, and was steady in large scale. So, the area of H. ammodendron Population fluctuation in the Gurbantunggut Desert was 8000-9200 m2 in suitable region,11600-14000 m2 in the region of poor condition.(4) In L(r) function (the derivation of Ripley’s K(r) function), aggregated distribution is the main trend as a whole and the scale ranges from 0m to 25m, while in g(r) function the case is similar within 5 meter s scale. Both the L(r) function and g(r) function show that with the development of the H.ammodendron from seedling and sapling into the adult, the distribution trend changes from aggregated to stochastic or uniform distribution in some scale. As to the spatial correlationship, positive correlation is shown in both the L(r) and the g(r) functions, but the scale is larger in L(r) function than that in g(r) function. In L(r) function the relationship between seedling and sapling or the grown tree is positive within 18m’s scale, while in g(r) function positive correlation is shown between the seedling and the sapling within 5m’s scale, whereas negative correlation is shown between the sapling and the adult within 8m’s scale. The intensity of the distribution of the H.ammodendron population has difference in varying topography.(5) The cycle characteristics of multiple scales patterns:we employed ecologically using Mexh and Morl wavelet methods to analyze the wave characteristics and their maintaining mechanisms of the H. ammodendron distribution in different sites and on different types of dunes. The results showed that ecologically using wavelet can distinguish H. ammodendron distributed in parallel-shaped, lattice-shaped and fork-shaped dunes with a main wave cycle of 165-180m,100-110m and 70-80m, respectively. In addition to the main wave cycle, ecologically using Morl wavelet also showed cycle phenomena on different scales. Therefore, H. ammodendron distribution pattern in a certain area can be predicted according to the wave cycles. The spatial distribution of H. ammodendron on different scales was affected by different factors. On large scale, the distribution was mainly affected by the type of dunes; on the mesoscale, the distribution was mainly affected by the aspect and length of the slopes; on the small scale, the distribution was mainly affected by soil moisture and salt content.(6) H.ammodendron Population fecundity:fecundity (bx) with the increase in age class show a growing trend, from the younger age group to age group, showing low→high→low tendency. Calculated on the basis of seeds of fertility parameters:the rate net added value was 734.78-2786.2, intrinsic rate of increase was 0.576-1.166, the average generation cycle of the H. ammodendron population was 6.8-11.457 years and the doubling time was 0.59-1.203 year and theoretically, the population quantity could double in less than one year. However, seedlings produced a doubling time was-215817-1789364, population doubling time is slow. In the loam ecological, H. ammodendron population in the longest life expectancy, the maximum fitness; reproductive value Vx, residual reproductive value RRV and the entire life cycle of the total reproductive value TRV of the cumulative values were consistent with r. In the loam and sandy types, H. ammodendron belongs to K strategist. In gravel type, various reproductive parameters changed, showing the characteristics of the r strategist, and in extreme saline type, showing the characteristics of the Plant life cycle form.(7) RA of H. ammodendron:RA in different edaphic types ranged from 0.64% to 1.5%. The relative frequency of flowering and bearing branches generally peaked at 0.5-2.0 cm. The RA had significant hierarchical variation and relationships between RA and assimilating shoots biomass could be fitted by linear or multinomial equations in four edaphic types. Both RA and reproductive output (RO) were size-dependent. Compared with loam and sandy soil, the RA in gravel soil was the biggest under severe condition. In conclusion, H. ammodendron in different soil types has varying evolutionary stable.(8) Multiple rings and age in H. ammodendron:Multiple rings numbers of H.ammodendron ranged from 2.9 to 5.9 per year, and widths ranged from 0.154 to 0.455mm per ring on tree rings. The weighted average age was 6.81 years, maximum age was 25 year in the saline soil. The weighted average age was 8.21 years, maximum age was 38 years in the gravel. The weighted average age was 14.59 years, maximum age was 55 year in the loam. The weighted average age wasl0.86 year, maximum age was 40 year in the sandy soil. The formation of multiple rings was completed in a long span, and we thought that multiple tree-rings in H.ammodendron inclined to be natural feature. Latewood formed by abundant paratracheal axial parenchyma with 22-35 small cell layers, and early wood consisting of abundant ray parenchyma with 4-15 cell layers.(9) Vegetation coverage, species richness and dune stability:The order of vegetation coverage and species richness was greatest in middle areas, followed by the eastern areas and with the western areas being sparse. On a large scale, precipitation from April to June determined the amount of vegetation coverage. On a small scale, vegetation coverage was influenced by:the type of terrain and the water and salt content in soils. Species richness of vegetation was determined by soil water and salt content on both the large and small scales. There also were remarkable differences in relative wind erosion among the different terrains and their order was:crest, slope, and inter-dune in descending order. The correlations between wind erosion and coverage and species richness of H.ammodendron community were influenced by the type of terrain.更多还原