沙坡头人工固沙植被土壤水分空间异质性

利用传统统计学和地统计学相结合的方法对沙坡头人工固沙植被区0～200 cm 之间的各层土壤水分的空间变异性进行研究.结果表明,1）土壤水分相对变异较大的层是在160～180 cm层和180～200 cm层,变异系数分别为0.72和0.73.表层0～5 cm层的相对变异也较大,变异系数为0.662）半方差函数分析结果表明,各层土壤水分均具有明显的空间变异性,各层土壤水分自相关部分的空间异质性占总空间异质性的程度很高,所占比例在87.7%～99.9%范围内.各层土壤水分的有效变程大小有较大差异,最小值出现在60～80 cm层(7.04 m),最大值出现在20～40 cm层(19.71 m),土壤水分有效变程从表层到深层没有明显的变化规律;3）土壤水分插值图反映出0～140 cm之间相邻各层土壤水分变化较大,140～200 cm各层土壤水分变化较小;4）土壤水分在0°、45°、90°、135°四个方向的半方差函数基本上是一条直线,表明在这四个方向上半方差和距离的相关性较低,土壤水分变化是独立、随机的,是同质性的.     

红松老龄林主要树种的空间异质性特征与比较的定量研究

 空间异质性研究对认识不同尺度上的生态系统结构、功能和过程具有重要的理论意义。采用地统计学理论和方法,通过空间异质性特征和比较研究了我国东北红松老龄林中主要树种,即红松(Pinus koraiensis)、云杉(Picea koraiensis)、冷杉(Abies nephrolepis)、枫桦(Betula costata)和紫椴(Tilia amurensis)的空间异质性程度、空间异质性组成、尺度和格局问题。结果表明：红松老龄林中主要树种虽然生长在同一林分中,但是它们的空间异质性与格局具有明显的差异。红松的空间异质性程度最高,分数维较低,其空间异质性主要由空间自相关部分组成,在450m的尺度内,具有明显的空间格局。枫桦的空间异质性程度最低,分数维最大,空间异质性主要由随机部分组成,在大于100m的尺度上不存在明显的空间格局。云杉和冷杉由于生长的立地相似,因此具有相似的空间异质性特征和格局。紫椴是红松最重要的伴生树种,其空间异质性程度、空间异质性组成、尺度和格局等方面与红松接近。红松老龄林中主要树种空间异质性与格局在一定尺度上的差异,反映这些树种在生态系统中具有不同的生态学功能和过程。     

放牧和刈割条件下草山草坡群落空间异质性分析

采用变异矩分析和分形方法,研究了草山草坡群落在放牧和刈割条件下的空间异质性及空间自相关性,结果表明,群落空间格局有尺度依赖性,刈割条件下空物异质性及空间相关性弱,多样性梯度即β多样性小,放牧消除地形引起的样地差异,因而使空间异质性简单化。     

Spatial distribution and density dependent growth and flowering of Asphodelus aestivus Brot.

Distribution patterns of A. aestivus at four different sites of a degraded mediterranean-type ecosystem (asphodel desert), Thessally, Greece, have been studied. A first order spatial structure was identified at small block sizes and was related to asexual reproduction, a second order structure, at large block sizes, was related to sexual reproduction. Spatial distribution of A. aestivus was associated with soil depth while ecological neighbourhood was discussed in relation to degradation phenomena, especially erosion. Density dependent growth of aboveground biomass and flowering has also been explored. Self-thinning was not detected, whereas the percentage of plants flowering decreases linearly with density and this was attributed to competition for nutrients. A reciprocal equation describes the growth of the aboveground biomass with time. A two-sided competition was displayed by initial plant weight, while the rate of growth of the aboveground biomass was proved independent of density.     

森林更新与空间异质性

森林更换是一个重要的生态学过程,一直是森林生态系统动态研究中的主要领域之一。森林更新受物理环境、自然干扰、人为干扰、更新树种特性、树种对干扰的反应等因素及其相互作用的影响。这些生物和非生物的因素随空间和时间而不断变化,构成了森林的空间异质性和时间异质性,使森林更新具有空间和时间上的变化特点,表现在异质性的格局和过程中。探索森林更新与空间异质性的内在规律,可揭示空间格局对更新的生态学过程的潜在作用机制。本文主要综述了近年来有关森林更新与空间异质性研究的主要内容和一些观点,分析了更新中空间异质性的来源,着重评述了空间异质性的生境及更新树种的反应、小尺度的空间异质性与更新动态、林分中光有效性的空间异质性与更新格局以及土壤和更新的空间异质性尺度的关联性等方面的研究。     

Seed and microsite limitations of recruitment and the impacts of post-dispersal seed predation at the within population level

Seed predation may cause important seed losses in plant populations, but its impact on the dynamics of populations will depend on the degree of seed or microsite limitations for recruitment. Seed losses will only affect recruitment if it is seed limited. The nature of recruitment limitation (seeds or microsites) is usually ascribed to whole plant populations but it may vary within populations among microhabitats and habitats. Thus, the potential impact of seed predation will also vary within the population, being highest where recruitment is seed limited. The impact to the whole population will depend on the spatial concordance between the intensity of seed predation and that of seed limitation. Recruitment limitations (with seed addition experiments), seed predation (with seed removal experiments), and the dynamics of seed availability in the soil (with soil samples taken both after seed dispersal and before the following dispersal event) of the shrub Corema album (Empetraceae) were investigated in dunes in NW Spain, at microhabitats ‘open ground’, ‘underneath C. album ♀’, and ‘underneath C. album ♂’ at two habitats, sparse and dense scrub. The nature of recruitment limitation (seeds vs. microsites) varied within the population. It was seed limited in the microhabitat ‘open ground’ and microsite limited under shrub cover. The spatial patterns of seedling recruitment were unrelated to seed availability but strongly affected by germination requirements. The spatial discordance between seed availability and recruitment implies a crucial constraint for processes affecting seed availability (seed predation but also e.g., dispersal) to impact recruitment. They will not affect its spatial pattern but only its quantity as long as they act in those sites selected by seeds to germinate. Seed predation was highest underneath mother plants and lowest in open ground. Thus, its potential impact is low, as it is centred where recruitment is not seed limited. This study shows that the analysis of seed predation in relation to recruitment limitations at smaller spatial scales within the population provides more insight to understand its impact.     

Soil pH and species diversity in coastal dunes

Soil pH was measured at two different spatial scales in coastal dunes on Norderney, North Sea, and in Mecklenburg-Vorpommern, Baltic Sea, Germany. Relationships between the variability in soil pH, species richness and species diversity are presented. Species richness and diversity were highest in grey dunes, where soil pH was at intermediate levels; both variables were lower in yellow and brown dunes. The variability in pH increased with increasing species diversity and also with scale. Overall, soil pH variability decreased with increasing vegetation cover. The lowest pH heterogeneity was found in heath dominated by Empetrum nigrum L. and grey dunes dominated by Campylopus introflexus (Hedw.) Brid. Increasing abundance of dominant species and decreasing species diversity of vegetation apparently reduces soil heterogeneity. Decreasing species diversity of vegetation is likely to explain decreasing variability in soil pH.     

空间异质性定量研究理论与方法

通过变异函数对空间异质性定量研究进行了讨论．结果表明,空间异质性定量研究应从空间特征和空间比较两方面去考虑．对空间特征,着重讨论怎样应用变异函数将空间异质性分解成各定量组分;确定空间异质性程度;探测空间异质性变化的尺度．对空间比较,怎样对同一变量和不同变量用变异函数比较空间异质性时的统计检验;采用标准化变异函数比较同一地点上的不同变量的空间异质性．最后通过阔叶红松景观中林型和土壤类型的空间异质定量研究实例验证了上述理论与方法．     

林分光照空间异质性对水曲柳更新的影响

 光照是森林更新动态中极为关键的环境因子。本研究在东北天然次生林中选择样地,应用地统计学理论结合实验生态学方法,定量分析林分光照空间异质性特征,同时进行林下播种水曲柳（Fraxinus mandshurica）的更新实验,探测更新格局特征。通过空间关联性分析,研究探讨是否林分光照的空间变异对水曲柳更新有重要影响作用。研究结果表明： 1）生长季林分平均光照仅为全光照的4.2%～4.6%,在空间分布上呈现非常明显的异质性特征,空间自相关变异（62.5%～78.2%）主要体现在10.9～12.4 m的尺度上。2）林分光照不同的空间样点上,水曲柳更新幼苗发生数量和秋季幼苗存活数量均存在显著差异,光照相对强的微生境中,更新苗发生数量较多且存活率高,而在光照较弱的微生境中则更新较差,更新具有十分明显的空间格局。3）更新格局与林分光照空间异质性特征紧密关联。在光照空间异质性程度较高、空间变异较复杂的条件下,更新相应呈现出较复杂的空间格局,自相关的变异表现在较小尺度范围（2.12～6.97 m）。在光照空间异质性程度较低、空间变异复杂性较小的条件下,更新格局的复杂程度明显变小,空间自相关变异（>83%）表现在较大的尺度上（30 m）,对更新格局起主要的影响作用,随机变异的影响很小（<17%）。这些研究结果说明,林分光照环境在水曲柳更新中的作用十分关键,林分光照的空间异质性对更新格局起决定性作用。     

东海带鱼和小型鱼类空间异质性及其空间关系

根据2001年秋季东海区121个调查站位的调查资料,以变异函数为工具,分析带鱼和7种小型鱼类(黄鲫、棘头梅童鱼、鳄齿鱼、六丝钝尾虎鱼、发光鲷、七星底灯鱼和细条天竺鲷)的空间异质性及其空间关系.结果表明,带鱼的变异函数曲线与细条天竺鲷、六丝钝尾虎鱼和发光鲷的曲线极为相似,对不同距离的变异函数值进行相关分析,带鱼与上述3种小型鱼类均达到极显著相关水平(P<0.01).黄鲫和棘头梅童鱼的变异函数表现出纯金块效应,而其它几种鱼都可拟合为球状或指数模型,并且都具有较强的空间自相关特性,其中细条天竺鲷、六丝钝尾虎鱼和发光鲷的变程也都接近或超过带鱼265km的变程,带鱼与这3种小型鱼类之间具有较强的空间追随关系,因此它们是带鱼的主要摄食对象.     

东海水域中上层鱼类资源的空间异质性

定量描述鱼类分布的空间变异,有利于从生态学意义上理解其空间分布及其与环境的关系,本文利用地理信息系统将东海区中上层鱼类资源密度空间化,运用空间自相关指数Geary c和变异函数理论分析其空间自相关和空间变异,东海区中上层鱼类资源空间分布平均场的Geary c指数为0．25,各向同性随机变异占总变异的19．1％,表明其空间分布具有较高的自相关特性,空间分布上各向变异不一致,其中45°和135°方向上变异曲线斜率急剧变化,表明这两个方向上存在重要的环境动力过程,各年份平均资源密度与相关变异(C)正相关,而与随机变异(C0)不存在相关,表明年际密度变化主要由空间自相关引起,变异曲线分维数(D)与密度呈负相关,说明密度的增加是由于鱼类在空间上的集聚程度增高引起的。     

用RISA法评估地下水细菌群落结构差异及变化

提出运用RISA法从细菌群落角度对垃圾填埋场地下水生态系统的空间异质性进行定量分析。RISA图谱的相似度聚类分析表明 :与随时间产生的变化相比 ,细菌群落在空间上的差异更大 ;同批取样不同位置和深度的地下水RISA图谱存在明显差异 ,整体上在 6 0 %～ 70 %相似度聚类。     

The spatial structure of the physical environment

There is substantial environmental variance at small spatial scales (1 m or less) in both natural and disturbed environments. We have investigated the spatial structure of physical variables at larger scales (up to 10⁶ m). We analysed surveys of edaphic properties of Wisconsin forest soils, of the water chemistry of lakes in Ontario and Labrador, and of temperature and precipitation in northeastern North America. We found no clear indication that the variance among sites approaches some maximal value as the distance between them increases. We suggest instead that the variance of the physical environment tends to increase continually with distance. The slope of the log-log regression of variance on distance provides a means of comparing the heterogeneity of different environments with respect to a given factor, or of comparing different factors within a given environment. This slope provides a useful measure of environmental structure that can be related to the biodiversity or plasticity of native organisms.     

Oscillatory reaction-diffusion equations on rings

We study the behavior of traveling waves in - systems on both homogeneous and inhomogeneous rings. The stability regions in parameter space of - waves were previously known [15, 19]; the results are extended here. We show the existence of Hopf bifurcations of traveling waves and the stability of the limit cycles born at the Hopf bifurcation for some parameter ranges. Using a Lindstedt-type perturbation scheme, we formally construct periodic solutions of the - system near a Hopf bifurcation and show that the periodic solutions superimposed on the original traveling wave have the effect of altering its overall frequency and amplitude. We also study the - system on an annulus ofvariable width, which does not possess reflection symmetry about any axis. We formally construct traveling waves on this variable-width annulus by a perturbation scheme, and find that perturbing the width of the annulus alters the amplitude and frequency of traveling waves on the domain by a small (order ²) amount. For typical parameter values, we find that the speed, frequency, and stability are unaffected by the direction of travel of the wave on the annulus, despite the rotationally asymmetric inhomogeneity. This indicates that the - system on a variable-width domain cannot account for directional preferences of traveling waves in biological systems.     

保安湖—湖湾大型水生植物群落格局的研究

用地质统计学中的半方差和双对数半方差图对保安湖-湖湾(黄风口)的大型水生植物群落格局进行了研究,在不同的尺度上对群落及其主要组成种类的空间异质性进行了定量的描述。结果表明：保安湖黄风口大型水生植物群落的双对数半方差图存在线性区域,群落具有分形特征(自相似性).在不同的尺度下,群落和各组成种类空间格局具有不同的分形维数值,异质性程度存在差异。但其异质性程度不高,建议进行群落调查时,样方尺度应取520m;单一种群调查时的样方尺度取380m.     

芦芽山鬼箭锦鸡儿灌丛营养特征及土壤养分分布规律

研究了芦芽山自然保护区亚高山草甸带鬼箭锦鸡儿(Caragana jubata)灌丛营养成分季节性变化和土壤养分分布规律.结果表明,鬼箭锦鸡儿具有很高的营养价值,粗蛋白含量达20.27%,粗纤维含量33.83%,灰分5.12%,同时含有丰富的Ca、Fe、Mn等中微量元素,是亚高山草场家畜的优质饲料来源.鬼箭锦鸡儿营养成分呈明显的季节性变化规律:从5月开始,随着灌丛生长发育,体内粗蛋白、灰分和矿质元素含量呈上升趋势,7月(开花期)达到最高,然后逐步降低.为适应海拔高、气温低、土层薄的亚高山草甸带生境, 鬼箭锦鸡儿灌丛周围的土壤养分向灌丛中心聚集,灌丛中心的土壤电导率、有机质、全氮、速效磷和有效钾分别较灌丛边缘高18.8%、16.4%、18.7%、16.6%和8.4%,形成了明显的\"肥岛效应\".鬼箭锦鸡儿灌丛根际土壤有机质、全氮出现富集,有效磷、速效钾和速效铁、锰在根际周围出现明显亏缺,表明鬼箭锦鸡儿具有高效固氮和吸收利用土壤养分的能力.