神农架地区河岸带中领春木种群数量特征与空间分布格局

 东亚特有珍稀濒危植物领春木(Euptelea pleiospermum)在神农架地区集中分布于河岸带中。为初步探讨领春木在河岸带集中分布的成因和维持机制, 在神农架地区4条河流——沿渡河、香溪河、南河和堵河的河岸带, 共设置了30个样方(20 m × 30 m), 从种群的大小级结构、静态生命表、存活曲线、空间分布格局及其动态5个方面分析了神农架地区河岸带中领春木种群的数量特征与空间分布格局。结果表明: 1) 幼龄期个体缺乏, 中龄期个体相对丰富, 老龄期个体数量稀少。纺锤型的大小级结构表明种群属于衰退型, 但是以萌蘖为主要更新方式使其种群在较长一段时间内得以维持; 2)现存的Ⅰ、Ⅱ级个体数少, 导致静态生命表中Ⅰ、Ⅱ级个体死亡率出现负值, 自疏现象造成第Ⅳ级个体出现死亡率高峰, 由于接近实际寿命, 在第Ⅶ级死亡率达到最高; 3) 虽然其幼苗存活率较低, 但由于其幼树的存活率较高, 其存活曲线接近DeeveyⅠ型, 表明该地区河岸带的环境条件较适宜领春木种群的生长; 4) 空间分布格局总体为聚集分布, 这与大多数珍稀植物种群一致。人为干扰和自然环境影响其分布格局, 使种群由聚集分布向随机分布发展。因此使领春木种群在河岸带中沿海拔呈现“一带多岛”现象; 5) 从幼龄期到中龄期再到老龄期, 不同发育阶段的领春木种群的分布格局由聚集分布逐渐变为随机分布。但由于分布格局受种群本身生物学特性、自然环境因素(如坡向和海拔)和人为干扰的影响, 领春木在不同河岸带中的分布格局有所差异。     

桂林岩溶石山青冈优势种群空间分布格局及关联分析

种群空间分布格局是研究种群特征、种间相互作用以及种群与环境关系的重要手段。青冈(Cyclobalanopsis glauca)是岩溶生态系统顶极群落的建种群，为进一步了解其种群空间分布格局特征，该研究根据样地调查规范对面积为60 m×60 m样地中的木本植物进行空间定位且进行每木调查，并运用点格局方法中的g(r)和L₁₂(r)函数对青冈幼苗(DBH<2 cm)、幼树(2 cm≤DBH<10 cm)和成树(10 cm≤DBH)进行空间分布特征和关联性分析。结果表明：(1)青冈种群的径级结构符合倒“J”型分布。(2)幼苗、幼树和成树在较小尺度上表现为聚集分布，而幼树和成树在中、大尺度上基本表现为随机分布。(3)不同径级个体空间关联性主要表现为幼苗与幼树在0～15 m尺度上呈正相关；幼树与成树在0～10 m尺度上呈不相关，而在10～15 m尺度上呈正相关；幼苗与成树在0～2 m尺度上呈不相关，而在2～15 m尺度上呈正相关。因此，青冈种群的分布格局及其关联性随空间尺度和发育阶段而变化，这是由种群自身的生物学特性、种内种间关系以及环境条件共同作用的结果。该研究...     

种群分布格局的多尺度分析

种群分布格局的分析对于了解种群空间分布规律以及种内与种间关系具有重要的意义。最近邻体分析方法 (Nearestneighboranalysis, NNA) 作为种群空间分布格局的重要分析方法, 仅局限于种群格局的单尺度分析。改进NNA方法以应用于种群格局的多尺度分析, 将有助于解决种群格局的尺度依赖性。该文在前人研究的基础上提出扩展最近邻体分析方法 (Extendednearestneighboranalysis, ENNA), 也即在传统Clark_Evans指数公式的基础上增加一个距离尺度参数d (m), 并定义其所对应的Clark_Evans 指数CE (d) 的计算公式及其相应的显著性检验计算公式 (u (d) ) 分别为 :CE (d) =rdA/rdE= (1Nd∑Ndi=1 rdi) / (0.5Ad/Nd+0.0 5 14Pd/Nd+0.0 4 1Pd/Nd3 /2 ) 和u (d) = (rdA-rdE) /σd, 在距离尺度d (m) 范围内, 参数rdA指样地内各个体与其最近邻体间距离的平均值 (m) 、rdE指相同环境中个体呈随机状态时最近邻体距离的平均值 (m) 、Nd 为样地内个体总数、rdi为第i个个体与其最近邻体间的距离 (m) 、Ad 为样地面积 (m2 ) 、Pd 为样地周长 (m) 和σd 代表标准差。ENNA尺度变换采用与分形理论中计算沙盒维数相类似的过程, 而格局类型判断的标准与传统最近邻体分析方法相同。传统最近邻体分析结果是EN NA中距离尺度d取最大值dmax时的一个特例。以广东省黑石顶自然保护区针阔叶混交林中的马尾松 (Pinusmas soniana) 、黄牛奶树 (Symplocoslaurina) 、水栗 (Castanopsisnigrescens) 、鼠刺 (Iteachinensis) 和桃金娘 (Rhodomyrtustomentosa) 等 5个代表性种群为例, 在地理信息系统软件ArcViewGIS技术平台上进行的实例研究显示, 5个种群均表现出不同程度的尺度相关性。由此表明, 该文提出的新方法ENNA能够检测出种群空间分布格局的尺度依赖性, 获得关于种群空间分布格局的多尺度信息, 是进行种群空间格局多尺度分析的有效方法。     

皖北石灰岩山地青檀种群不同发育阶段的点格局分析

基于皖北石灰岩山地青檀次生林的样地调查数据,采用空间代替时间和点格局O-ring统计法,研究了青檀种群的径级结构、不同发育阶段的空间分布格局及其相互关联性.结果表明:(1)不同样地青檀种群的径级结构大体呈倒“J”型,各径级均有个体分布,但主要集中在幼苗、幼树阶段,中树和大树较少,种群均属增长型.(2)幼苗、幼树和中树在个别小尺度上呈现出明显的聚集分布,且皇藏峪种群的聚集强度显著高于相山种群;随着尺度的增加,个体趋于随机分布.成树阶段的青檀个体均表现为随机分布或接近均匀分布.(3)各发育阶段间的空间关联主要表现在中、小尺度上,随着空间尺度的增加,空间关联性不显著.青檀种群结构和空间格局主要受群落生境的异质性、自身生物学特性(尤其是克隆繁殖)以及人为活动的干扰等因素影响.     

气候变暖对领春木沿海拔分布潜在影响的实验模拟

在神农架山地不同海拔高度进行领春木(Euptelea pleiospermum)种子萌发实验和萌发后实生幼苗的存活状况研究,模拟气候变化对领春木分布的潜在影响.结果显示:(1)林窗内种子萌发率显著高于林下,林下的幼苗全部死亡;(2)在领春木的分布上限(2090 m)和以上区域种子萌发率高,且幼苗死亡率低,在领春木的分布下限(900 m)和以下区域种子萌发率低,且除620 m阳坡林下以外,幼苗均全部死亡;(3)种源对领春木种子萌发率和幼苗死亡率均无显著影响;(4)冬季播种的种子比春季播种种子萌发率低,萌发后幼苗死亡率高.研究结果表明,珍稀植物领春木具备向高海拔地区迁移的潜能,但向高海拔的迁移扩散可能会受到一定的限制;在低海拔区域,领春木幼苗更新受到威胁,但一些小生境可以缓冲气候变暖带来的威胁.     

海南霸王岭陆均松空间分布格局及其与微生境异质性的关系

应用地统计学及限制性排序分析方法,对海南霸王岭陆均松(Dacrydium pectinatum)幼苗、幼树、成树及其微生境因子的空间分布特征进行分析。结果表明:1)陆均松不同生活史阶段空间分布格局存在明显差异,幼苗阶段表现为聚集性分布,具有显著的空间自相关结构,聚集强度随年龄增长呈逐渐减弱趋势;2)RDA分析表明,陆均松空间分布格局与微生境因子的关系在不同生活史阶段存在差异,生境过滤的影响会随着生活史阶段的不同而有所差别;3)微生境变量对陆均松幼苗、幼树、成树空间变异的总解释量分别为78.4%、41.2%、33.6%,微生境因素对陆均松分布的限制作用主要集中在幼苗阶段;4)在大尺度条件下,PCNM变量与微生境变量具有较大的共同解释量(22.2%),存在典型的"诱导空间变差"现象,微生境变量空间变化引起响应变量即陆均松幼苗、幼树、成树的分布产生类似的空间结构。研究结果证实了微生境因子与不同生活史阶段陆均松分布的关联性,为深入理解陆均松种群维持机制、空间分布格局、更新动态与生境的关系提供科学依据。     

湖北九宫山成熟常绿落叶阔叶混交林3种优势种的邻域效应研究

以最近邻株距离统计研究了湖北九宫山成熟常绿落叶阔叶混交林3种优势种青冈栎(Cyclobalanopsis glauca)、甜槠(Castanopsis eyrei)和短柄枹栎(Quercus serrata var.brevipetiolata)的邻域效应,进而探讨了局域尺度上的竞争/帮促关系与物种共存格局.结果显示,青冈栎、甜槠和短柄枹栎的最近邻株距离不存在下限;青冈栎的胸径大小与其种内最近邻株距离存在正相关(p=0.029),甜槠的胸径大小与种内、种间最近邻株距离均无相关性(p≥0.360),而短柄枹栎的胸径大小与种间最近邻株距离为负相关(p=0.040);3树种中任意一个的种内与种间最近邻株距离都没有显著差异(p≥0.122).这些结果表明,九宫山成熟常绿落叶阔叶混交林内邻域尺度上的竞争排斥并未充分激化,但是青冈栎的种内竞争仍然在起作用,而甜槠的竞争效应不明显,短柄枹栎则依赖种间帮促甚于相互竞争.同种和异种之间的排斥效果没有差异表明局域尺度的物种共存格局可能出于随机过程而非负密度制约过程.     

湖北九宫山成熟常绿落叶阔叶混交林 3种优势种的邻域效应研究

以最近邻株距离统计研究了湖北九宫山成熟常绿落叶阔叶混交林3种优势种青冈栎(Cyclobalanopsis glauca)、甜槠(Castanopsis eyrei)和短柄枹栎(Quercus serrata var.brevipetiolata)的邻域效应,进而探讨了局域尺度上的竞争/帮促关系与物种共存格局。结果显示,青冈栎、甜槠和短柄枹栎的最近邻株距离不存在下限;青冈栎的胸径大小与其种内最近邻株距离存在正相关(p= 0.029),甜槠的胸径大小与种内、种间最近邻株距离均无相关性(p≥ 0.360),而短柄枹栎的胸径大小与种间最近邻株距离为负相关(p= 0.040);3树种中任意一个的种内与种间最近邻株距离都没有显著差异(p≥ 0.122)。这些结果表明,九宫山成熟常绿落叶阔叶混交林内邻域尺度上的竞争排斥并未充分激化,但是青冈栎的种内竞争仍然在起作用,而甜槠的竞争效应不明显,短柄枹栎则依赖种间帮促甚于相互竞争。同种和异种之间的排斥效果没有差异表明局域尺度的物种共存格局可能出于随机过程而非负密度制约过程。     

阔叶红松林大径级个体对树木空间分布的影响

对森林空间结构的研究一直是生态学重要研究内容之一,林分中大径级个体直接影响周围林分的空间格局,当大径级个体成为倒木或枯立木时会造成较大林隙,这也将导致周围空间格局发生变化。利用小兴安岭凉水自然保护区内10.4 hm2样地的调查数据,统计了样地内乔木树种组成,分析计算样地内树木个体间的分布规律,探究大径级个体对周围邻木空间分布的影响。研究结果表明:样地中共有乔木24种,共计7412株(去除分株),隶属于11科18属,林分中大径级个体周围存在由小径级树木聚集生长形成的环形结构,该环形结构随着邻木径级的变化而变化,2级邻木(5.0≤DBH10.0 cm)主要在距离大径级个体3—7m范围内形成环形结构,3级邻木(10.0≤DBH30.0 cm)主要在距离大径级个体3—6 m范围内形成环形结构,而1级邻木(1.0≤DBH5.0 cm)与4级邻木(30.0≤DBH50.0 cm)并未形成环形结构,经分析环形结构的产生与林分内个体间的竞争存在密切关系,并且该结构与林隙斑块动态理论间存在内在联系,该结构是森林动态变化的一种表现形式,会伴随林木的生长产生或消失。另外研究表明大径级个体胸径的变化对邻木的环形结构分布范围也有一定影响,当大径级个体胸径增加时邻木的聚集范围有收缩的趋势。本次实验采用单次获取的林木数据,对于环形结构随时间的变化情况还有待进一步探究。     

海南岛霸王岭热带雨林的种间分离

基于地理信息系统软件绘制了海南岛霸王岭热带雨林 1个 0 .5hm2 永久样地所有DBH≥ 1cm树木的分布图 ,进而借助最近邻体分析扩展模块判定每个个体的最近邻体植株 ,并得到每个基株 最近邻体种对的距离。采用N×N最近邻体列联表的截表法 ,研究了这个多物种群落的种间分离。结果表明 ,随机毗邻种对占优势 ,正分离种对次之 ,负分离种对最少。多数灌木和一些小乔木 (平均胸径 <1 5cm)彼此呈正分离 ,少数负分离 ;灌木和乔木间的分离关系复杂 ;大乔木种类 (平均胸径≥ 65cm)间不存在负分离。种间分离存在种间差异。种间分离与分布格局明显相关 ,聚集分布的物种与其它物种正分离比例远比随机分布、均匀分布大 ;相反 ,聚集分布物种与其它物种负分离比例要比随机分布、均匀分布小。聚集 聚集分布的种对最可能出现正分离 ;聚集 均匀分布的种对以及随机 随机分布的种对则最可能出现负分离。但是 ,无论物种的分布格局或种对相对分布格局如何 ,随机毗邻的种对都占优势。与种间联结不同 ,种间分离反映的是小尺度的物种空间关系。在此基础上 ,初步阐述了种间分离的可能原因及其生态学涵义     

Environmental Correlates of Tree and Seedling–Sapling Distributions in a Mexican Tropical Dry Forest

Bray and Curtis ordination was used to explore which environmental variables explained importance values and the presence–absence of tropical tree seedlings, saplings and adults in La Escondida-La Cabaña, Sierra de Manantlán, Jalisco, Mexico. The diameters of trees ≥2.5 cm DBH and the presence and height of seedlings and saplings were measured in nine 0.1 ha sites. Four matrices including presence–absence data and importance value indices for trees and seedlings and saplings were analyzed through Bray and Curtis ordination. The matrices were based on density, frequency, and dominance of adult trees as well as seedlings and saplings. The environmental matrix consisted of 18 variables, including elevation, slope, canopy gaps, disturbance, and soil variables. We recorded 63 tree species and 38 seedling and sapling species in the nine sites. The ordination explained 70.9% of the variation in importance value data for trees and 62.6% for seedlings and saplings. The variation explained in presence–absence data for trees was 67.1 and 77.4% for seedlings and saplings. The variance in the ordination axes of seedlings and sapling presence–absence data was poorly explained by the number of gaps in the tree, shrub, or herb layer, suggesting little light specialization by seedlings and saplings. Habitat specialization for soil nutrients appears to be important in explaining the presence–absence of seedlings and saplings. Seedling and sapling specialization along different soil microsites could promote species coexistence in this forest, while heterogeneity in light conditions may instead determine differences in growth and, thus, importance value of trees. We hypothesize that in tropical dry forest in Jalisco, Mexico, a habitat specialization for soil resources is likely more importance at early stages in tree life histories than in later life history.     

濒危植物闽楠幼苗更新及环境解释

为了更好地理解濒危植物闽楠幼苗天然更新与微环境的关系,以广西富川县蚌贝村闽楠天然林胸径5.0 cm以下的更新个体为研究对象。基于0.64 hm₂^{固定监测样地调查数据,采用Pearson相关系数、冗余分析等方法对幼苗更新密度与样地微环境因子关系进行分析。结果表明：(1)闽楠小幼苗更新个体数最多,随龄级增加更新密度呈下降趋势;幼苗向幼树转化率低,小幼苗向中幼苗转化率是闽楠更新成功的关键阶段;(2)闽楠幼苗更新密度与样地灌木层高度、最近母树距离、灌木层覆盖度极显著正相关,与样地光照、草本层覆盖度显著负相关; (3)灌木层高度、最近母树的距离、灌木层覆盖度、叶面积指数、光照、草本层覆盖度、凋落物厚度、土壤盐分是影响闽楠幼苗更新的主要微环境因子,光照和草本层覆盖度是闽楠幼苗更新的限制因子。因此,降低光照强度、减少草本层的覆盖度、增大灌木层的覆盖度等有利于闽楠种群更新发展。}     

PERMANENT GENETIC RESOURCES: Development and characterization of 14 polymorphic microsatellite loci in the endangered tree Euptelea pleiospermum (Eupteleaceae)

Fourteen polymorphic microsatellite loci were developed and characterized for the endangered and tertiary relict tree, Euptelea pleiospermum. A genomic DNA enrichment protocol was used to isolate microsatellite loci and polymorphism was explored using 32 individuals from one natural population. The observed number of alleles ranged from two to nine. The ranges of observed and expected heterozygosities were 0.25-1.00 and 0.22-0.85, respectively. These microsatellite markers provide powerful tools for the ongoing conservation genetic studies of E. pleiospermum.     

Life stage,not climate change,explains observed tree range shifts

Ongoing climate change is expected to shift tree species distribution and therefore affect forest biodiversity and ecosystem services. To assess and project tree distributional shifts, researchers may compare the distribution of juvenile and adult trees under the assumption that differences between tree life stages reflect distributional shifts triggered by climate change. However, the distribution of tree life stages could differ within the lifespan of trees, therefore, we hypothesize that currently observed distributional differences could represent shifts over ontogeny as opposed to climatically driven changes. Here, we test this hypothesis with data from 1435 plots resurveyed after more than three decades across the Western Carpathians. We compared seedling, sapling and adult distribution of 12 tree species along elevation, temperature and precipitation gradients. We analyzed (i) temporal shifts between the surveys and (ii) distributional differences between tree life stages within both surveys. Despite climate warming, tree species distribution of any life stage did not shift directionally upward along elevation between the surveys. Temporal elevational shifts were species specific and an order of magnitude lower than differences among tree life stages within the surveys. Our results show that the observed range shifts among tree life stages are more consistent with ontogenetic differences in the species' environmental requirements than with responses to recent climate change. The distribution of seedlings substantially differed from saplings and adults, while the distribution of saplings did not differ from adults, indicating a critical transition between seedling and sapling tree life stages. Future research has to take ontogenetic differences among life stages into account as we found that distributional differences recently observed worldwide may not reflect climate change but rather the different environmental requirements of tree life stages.     

Variable rainfall has a greater effect than fire on the demography of the dominant tree in a semi‐arid Eucalyptus savanna

Rainfall, fire and competition are emphasized as determinants of the density and basal area of woody vegetation in savanna. The semi‐arid savannas of Australia have substantial multi‐year rainfall deficits and insufficient grass fuel to carry annual fire in contrast to the mesic savannas in more northern regions. This study investigates the influence of rainfall deficit and excess, fire and woody competition on the population dynamics of a dominant tree in a semi‐arid savanna. All individuals of Eucalyptus melanophloia were mapped and monitored in three, 1‐ha plots over an 8.5 year period encompassing wet and dry periods. The plots were unburnt, burnt once and burnt twice. A competition index incorporating the size and distance of neighbours to target individuals was determined. Supplementary studies examined seedling recruitment and the transition of juvenile trees into the sapling layer. Mortality of burnt seedlings was related to lignotuber area but the majority of seedlings are fire resistant within 12 months of germination. Most of the juveniles (≤1 cm dbh) of E. melanophloia either died in the dry period or persisted as juveniles throughout 8.5 years of monitoring. Mortality of juveniles was positively related to woody competition and was higher in the dry period than the wet period. The transition of juveniles to a larger size class occurred at extremely low rates, and a subsidiary study along a clearing boundary suggests release from woody competition allows transition into the sapling layer. From three fires the highest proportion of saplings (1–10 cm dbh) reduced to juveniles was only 5.6% suggesting rates of ‘top‐kill’ of E. melanophloia as a result of fire are relatively low. Girth growth was enhanced in wet years, particularly for larger trees (>10 cm dbh), but all trees regardless of size or woody competition levels are vulnerable to drought‐induced mortality. Overall the results suggest that variations in rainfall, especially drought‐induced mortality, have a much stronger influence on the tree demographics of E. melanophloia in a semi‐arid savanna of north‐eastern Australia than fire.     

Distance- and density-dependent leaf dynamics of seedlings of a tropical rainforest tree

Parental distance and plant density dependence of seedling leaf turnover and survival was examined to investigate predictions of the Janzen–Connell hypothesis. The focal study species, Shorea macroptera is a canopy tree species in a lowland rain forest in peninsular Malaysia. We found that the peak of the distribution of plants shifted from 3–6 m to 6–9 m during the course of the change from seedling to sapling stage. The leaf demography of the seedlings was influenced by their distance from the adult tree and also by the seedling density. Although significant density- and distance dependence in leaf production was not detected, seedling leaf loss decreased with distance from the parent tree and with seedling density. Similarly, leaf damage was not found to be distance- or density-dependent, but net leaf gain of seedlings increased with distance from the parent tree. Although no significant distance- or density-dependence was evident in terms of leaf damage, significant distance dependence of the net leaf gain was found. Thus, we concluded that positive distance dependence in the leaf turnover of seedlings may gradually contribute to a shift in the distribution pattern of the progeny through reductions in growth and survivorship.     

Patterns of tree replacement: canopy effects on understory pattern in hemlock-northern hardwood forests

The effect of canopy trees on understory seedling and sapling distribution is examined in near-climax hemlock-northern hardwood forests in order to predict tree replacement patterns and assess compositional stability. Canopy trees and saplings were mapped in 65 0.1-ha plots in 16 tracts of old-growth forests dominated by Tsuga canadensis, Acer saccharum, Fagus grandifolia, Tilia americana, and Betula lutea in the northeastern United States. Seedlings were tallied in sub-plots. Canopy influence on individual saplings and sub-plots was calculated, using several indices for canopy species individually and in total. For each species sapling and seedling distributions were compared to those distributions expected if saplings were located independently of canopy influence. Non-random distributions indicated that sapling and seedling establishment or mortality were related to the species of nearby canopy trees. Hemlock canopy trees discriminate against beech and maple saplings while sugar maple canopy favors beech saplings relative to other species. Basswood canopy discourages growth of saplings of other species, but produces basal sprouts. Yellow birch saplings were rarely seen beneath intact canopy. Since trees in these forests are usually replaced by suppressed seedlings or saplings, canopy-understory interactions should influence replacement probabilities and, ultimately, stand composition. I suggest that hemlock and basswood tend to be self-replacing, maple and beech tend to replace each other, and birch survives as a fugitive by occupying occasional suitable gaps. This suggests that these species may co-exist within stands for long periods with little likelihood of successional elimination of any species. There is some suggestion of geographical variation in these patterns.     

Predicting Species Response to Disturbance from Size Class Distributions of Adults and Saplings in a Jamaican Tropical Dry Forest

The diversity of tropical dry forests is poorly described and their regeneration ecology not well understood, however they are under severe threat of conversion and degradation. The Hellshire Hills constitute a dry limestone forest reserve on the south coast of Jamaica that is of high conservation value. In order to describe the structure and composition of this forest and assess the extent to which the population structures of its tree species do characterize their regeneration ecologies, pre-disturbance structure, floristics and seedling populations were compared with post-disturbance species responses in twelve 15 m × 15 m permanent sample plots which were laid out in a blocked design in April 1998, giving a total sample area of 0.27 ha. These plots were subjected to disturbance in April 1999 (cutting) with each of four blocks being assigned with two randomly allocated treatment plots (partially and clear cut) and one control plot (uncut). A total of 1278 trees (≥2 cm DBH) and 7863 seedlings and saplings (0–2 mm and 2–20 mm root collar diameter (RCD) respectively), comprising 60 and 52 species, respectively, were sampled in the plots prior to disturbance. The species-area curve for trees reached a maximum at 0.20 ha, and abundance was widely distributed amongst the species (26 had importance values greater than 1%); four species were notably codominant (with importance values between 7 and 8%). The forest stand structure had a reverse J-shaped curve for tree and for seedling/sapling size-class distributions, which indicated that the forest as a whole was probably regenerating adequately. From an analysis based on adult and sapling size-class distributions (SCDs), 21 species with 15 or more individuals were classified into 3 groups. Many of the species (15 of the 21), had flat adult SCDs that deviate from the whole-community reverse J-shaped SCD. However, sapling SCDs for 6 of the 15 species were strongly positive indicating the potential for their populations to be sustained by recruitment from the saplings present. No general association was found between these SCD species groupings and the actual ability of the species to recover from disturbance. Analysis of post-disturbance response revealed that for only 9 of the 21 species did adult SCDs provide adequate prediction, but for an additional 6 of the species information on sapling SCDs improved the accuracy of prediction if the ‘release’ of saplings or smaller individuals predominated recovery. However in this forest, recovery following disturbance which left stem and roots in place is predominantly by coppice regrowth, and there were no significant correlations found between adult SCDs and the species’ ability to coppice.     

Dispersion pattern and mortality of seeds and seedlings ofFagus crenata Blume in a cool temperate forest in western Japan

The seed and seedling mortality ofFagus crenata Blume after a mast year (1993) was examined in relation to density and distance from the nearest conspecific adult tree in a mixed conifer-hardwood forest in Ohdaigahara, western Japan. The mortality of fallen seeds during winter amounted to 93.7%, and 79.2% of the current-year seedlings died in the first growing season. The most important factor of death for both seeds and seedlings was predation by vertebrates. The mortality of seeds during winter was positively correlated with sound seed density. The mortality of seedlings was positively correlated with density but not significantly related to the distance from the nearest crown edge of a conspecific adult tree. Mortality patterns varied with stages and spatial scales due to the behavior of predators; it is thus important to investigate the spatial pattern of seeds and seedling mortality at various temporal and spatial scales. After the first growing season, the difference in seedling density between distance classes was not significant at <4m from the nearest adult trees due to density-dependent mortality. However, seedling density was significantly lower in the ≥4 m class than in the <4 m classes.