Ramet Population Structure of Fargesia nitida （Mitford） Keng f. et Yi in Different Successional Stands of the Subalpine Coniferous Forest in Wolong Nature Reserve

Forest structure and succession in Wolong Nature Reserve is influenced by the understory dwarf bamboo population. However, less is known about how the forest succession affects the dwarf bamboo population. To examine the bamboo ramet population growth of Fargesla nitida （Mltford） Keng f. et Yi and to determine how ramet population structure varies along the succession of coniferous forest, we sampled ramet populations of F. nitida from the following three successional stages： （i） a deciduous broad-leaved （BL） stand; （ii） a mixed broad-leaved coniferous （MI） stand; and （ill） a coniferous （CF） stand. We investigated the population structure, biomass allocation, and morphological characteristics of the bamboo ramet among the three stand types. Clonal ramets, constituting the bamboo population, tended to become short and small with succession. The ramet changed towards having a greater mass investment in leaves, branches and underground roots and rhizomes rather than in the culm. With respect to leaf traits, individual leaf mass and area in the BL stand were markedly bigger than those In both the MI and CF stands, except for no significant difference in specific leaf area. The age distribution showed that the bamboo population approached an older age with succession. The results demonstrate that the ramet population structure of F. nitida is unstable and its growth performance is inhibited by succession.     

卧龙亚高山暗针叶林不同林冠环境下华西箭竹分株种群结构特征

详细调查了林下、中林窗、大林窗和林缘旷地等4种亚高山暗针叶林林冠环境下的华西箭竹（Fargesia nitida）分株种群,对其表现结构（株高、基径和生物量）和年龄结构进行了较系统的对比研究.主要研究结果如下：（1）分株水平上,华西箭竹表现结构在4种林冠环境下均有极显著差异（p＜0.01）,且随林冠郁闭度的减小,分株个体的高度、基径和生物量有递增的趋势（林下＜中林窗＜大林窗）;（2）分株各构件在总生物量中所占比例随林冠环境变化而改变：除林缘旷地外,叶的生物量百分比与林冠郁闭度呈正相关.林缘旷地中,地下茎和根系的生物量百分比均高于其余3种环境;（3）不同林冠环境下分株单位叶面积叶重存在显著差异（p＜0.05）,且随林冠郁闭度的减小而增大.单叶生物量和单叶面积均以中林窗最大,林缘旷地次之,二者与大林窗或林下均有显著差异（p＜0.05）.华西箭竹的单株叶片数量以大林窗最大,与其余3种环境有极显著差异（p＜0.01）;（4）分株种群的死亡率以林下最低（P＜0.01）,但各种群平均年龄间无显著差异（p＞0.05）.可见,华西箭竹分株种群对林冠环境变化的反应主要体现在形态和生物量分配上,而非种群的年龄上.     

Response of clonal plasticity of Fargesia nitida to different canopy conditions of subalpine coniferous forest

The aim of this study is to explore the effects of canopy conditions on clump and culm numbers, and the morphological plasticity and biomass distribution patterns of the dwarf bamboo species Fargesia nitida. Specifically, we investigated the effects of canopy condi-tions on the growth and morphological characteristics of F. nitida, and the adaptive responses of F. nitida to dif-ferent canopy conditions and its ecological senses. The results indicate that forest canopy had a significant effect on the genet density and culm number per clump, while it did not affect the ramet density. Clumps tended to be few and large in gaps and forest edge plots, and small under forest understory plots. The ramets showed an even distribution under the closed canopy, and clus-ter distribution under gaps and forest edge plots. The forest canopy had a significant effect on both the ramets'biomass and biomass allocation. Favourable light conditions promoted ramet growth and biomass accumulation. Greater amounts of biomass in gaps and forest edge plots were shown by the higher number of culms per clump and the diameter of these culms. Under closed canopy, the bamboos increased their branching angle, leaf biomass allocation, specific leaf area and leaf area ratio to exploit more favourable light conditions in these locations. The spacer length, specific spacer length and spacer branching angles all showed significant differences between gaps and closed canopy conditions. The larger specific spacer length and spacer branching angle were beneficial for bamboo growth, scattering the ramets and exploiting more favourable light conditions. In summary, this study shows that to varying degrees, F nitida exhibits both a wide ecological amplitude and high degree of morphological plasticity in response to differing forest canopy conditions. More-over, the changes in plasticity enable the plants to optimize their light usage efficiency to promote growth and increase access to resources available in heteerogeneous light environoments.     

贵州雷公山秃杉林不同林冠环境下箭竹分株种群结构特征

通过对贵州雷公山秃杉林的4种林冠环境,即林下(FU)、中林窗(MG)、大林窗(LG)和林缘旷地(FEW)内的箭竹的分株种群结构（包括株高、基径、生物量、叶和分株数等）和年龄结构进行较系统对比研究。结果显示:（1)从林下→中林窗→大林窗,箭竹分株种群的株高(h)、基径（bd)与生物量显著增加。（2)在4种林窗环境中,箭竹各构件的生物量的百分比发生相应变化,枝和叶片生物量的百分比沿林下→中林窗→大林窗→林缘旷地的顺序显著减小,在林缘旷地,地下茎、粗根（d＞0.5 mm)和细根（d≤0.5 mm)生物量的百分比显著高于其他3种林冠环境。（3)箭竹分株单位叶面积叶重沿林下→中林窗→大林窗→林缘旷地的顺序显著增大,单叶生物量与叶面积以中林窗最大,林缘旷地次之,二者与大林窗或林下差异显著;大林窗的单株叶片数显著高于其余3种林冠环境。（4)在4种林冠环境中,箭竹分株种群死亡率以林下最低,但各种群平均年龄间无显著差异。研究表明,箭竹分株种群对林冠环境变化的响应主要体现在形态与生物量的分配上,而非种群的年龄。     

野化培训大熊猫采食和人为砍伐对拐棍竹无性系种群更新的影响

亚高山竹类占据着野生大熊猫(Ailuropoda melanoleuca)食物组分的99%,竹子的生命周期与大熊猫的生活史密切相关,竹子的更新和生长直接影响着大熊猫的生存与保护.为了弄清大熊猫的采食利用和人为砍伐是否促进或制约竹子的繁殖更新,应用样方法、定位观察法,连续研究了卧龙自然保护区大熊猫栖息地内野化培训大熊猫采食、人为砍伐和对照样方中拐棍竹无性系种群的更新动态.结果表明,在相同种群数量和环境条件的基础上(p>0.05),被大熊猫采食竹子的比例为67.07%,致死率29.07%;人为砍伐竹子的比例为65.67%,致死率46.68%,可见与大熊猫采食相比,砍伐更为影响拐棍竹种群的生存.从出笋数量来看,不同处理方式有利于拐棍竹无性系种群的更新(p<0.05),尤其是人为砍伐措施大大提高了竹子的出笋率,但人为砍伐样方的竹笋质量(地径和株高生长)却远低于大熊猫采食和对照样方,未能达到大熊猫觅食的选择利用标准.不同年份之间,各种处理方式下的拐棍竹出笋数量波动较大(p=0.006～0.035),并随着恢复时间的延长,逐渐趋于相似(2007,p=0 825).不同处理方式之间,拐棍竹无性系种群的年补充率,各年份均具有显著性差异(p<0.05,除2007年外),年死亡率仅2003年和2004年有明显的差异(p<0.05),2005～2007年均不显著(p>0.05).拐棍竹无性系种群的年补充率与年死亡率之间表现出年补充率﹥年死亡率的格局(p<0.05),唯有大熊猫采食样方的2004年和2005年、人为砍伐和对照样方的2005年的年死亡率略高于年补充率(p>0.05),这表明拐棍竹无性系种群对大熊猫采食和人为砍伐具有无性系整合的补偿效应.     

Effects of dwarf bamboo, Fargesia nitida (Mitford) Keng f. ex Yi, on bark stripping by ungulates in a subalpine Abies faxoniana Rehder & E. H. Wilson forest, southwest China

Incidence and intensity of bark stripping of trees by ungulates was investigated at no bamboo (Fargesia nitida (Mitford) Keng f. ex Yi) (B-) site and understory bamboo dominant (B+) site of a subalpine Abies faxoniana Rehder & E. H. Wilson forest, southwest China. The percentage of damaged trees in B-site was higher than in B+ site. Bark stripping obviously occurred more frequently on Abies faxoniana compared to other tree species. Appearance of stripped bark and dead stems of the trees in different size-classes of A. faxoniana strongly depended on the density of dwarf bamboo at the site, and also on the size and bark structure of the trees, with highest damage rates occurring on the smaller DBH classes (10–40 cm) in B-site. The bark stripping intensity of A. faxoniana decreased significantly with higher density and coverage of F. nitida around damaged trees. Therefore, there is an indirect negative effect of the distribution of dwarf bamboo, F. nitida, on bark stripping of tree species. We suggest the indirect effects of dwarf bamboo species should be taken into account while considering the succession and regeneration of natural forests.     

卧龙自然保护区落叶松林不同恢复阶段地表甲虫的多样性

在四川卧龙国家自然保护区,以落叶松种植林邻近的天然落叶阔叶林(100年生,5块样地)为对照,分别选择刚种植(5年生)、幼年期(15年生)和成熟期(45年生)的3种落叶松林各4块样地,每个样地4个重复,研究森林不同恢复阶段地表甲虫的多样性。通过巴氏罐诱法取样,采集甲虫标本共7444号。步甲科、隐翅虫科和拟步甲科分别占总数的40·2%、38·3%和6·4%,共同构成本研究地区的优势类群。甲虫的科丰富度、多样性和均匀度在3种落叶松林内显著高于天然林,且在3种落叶松林中,刚种植的最高,幼年期的最低;个体数量正相反,天然林显著高于落叶松林,而且3种落叶松林内,幼年期最高,刚种植的最低。主坐标分析排序和聚类分析表明,不同树龄的落叶松林和天然阔叶林间的地表甲虫群落组成存在显著差异,成熟期落叶松林与幼年期落叶松林和天然阔叶林有较高的相似性。甲虫个体数量的季节变化在3种落叶松林内相似性很高,与天然阔叶林差异显著,而科丰富度、多样性和均匀度的季节变化在3种落叶松林以及天然阔叶林间相似性都很低。多元回归分析表明,林冠层、草本层及枯落物的高(厚)度和覆盖率是决定科丰富度、个体数量、多样性和均匀度的决定因素。以上结果表明,在科级水平上,地表甲虫群落组成在不同树龄的落叶松林以及天然落叶阔叶林内存在显著差异,虽然成熟期的落叶松林已经具有了部分天然阔叶林的甲虫群落特点,但仍无法完全恢复到天然林的群落水平。因此,在鼓励森林恢复的同时,保留大面积的天然落叶阔叶林免受破坏和干扰仍然是保护地表甲虫群落的必要措施。     

Successional loss of two key food tree species best explains decline in group size of Panamanian howler monkeys (Alouatta palliata)

Negative impacts of discrete, short‐term disturbances to wildlife populations are well‐documented. The consequences of more gradual environmental change are less apparent and harder to study because they play out over longer periods and are often indirect in their action. Yet, they can drive the decline of wildlife populations even in seemingly pristine and currently well‐protected habitats. One such environmental change is a successional shift in a community's species composition as it regenerates from disturbance caused by past human land use. Early and middle successional tree species often provide key foods to folivores and frugivores, but the abundance of these resources drops as the forest matures, with adverse repercussions for these consumers. Our 44‐year record (1974–2018) of howler monkey (Alouatta palliata) group sizes and demographic composition from Barro Colorado Island, Panama, a protected reserve, documents an example of this phenomenon. After 70 years of relative stability, the mean size of howler monkey groups exhibited a marked decline, beginning in 2003. This downward trajectory in group size has continued through the most recent census in 2018. The composition of howler groups also changed significantly during the study period, with the patterns of decline differing among age/sex classes. There is no evidence that these changes were caused by increased rates of emigration, group fission, predation, parasitism, or disease. Rather, they are best explained by an island‐wide, succession‐driven decline in the densities of two species of free‐standing fig trees, Ficus yoponensis and F. insipida, which together were providing ~36% of BCI howlers’ annual diet. Abstract in Spanish is available with online material.     

椴树阔叶红松林群落主要树种径级结构研究

椴树阔叶红松林群落主要树种径级结构研究孙伟中代力民章一平（中国科学院沈阳应用生态研究所,１１００１５）ＳｔｕｄｙｏｆＤｉａｍｅｔｅｒＢｒｅａｓｔＨｉｇｈＳｔｒｕｃｔｕｒｅｏｆｔｈｅＭａｉｎＴｒｅｅｓｉｎＴｉｌｉａＢｒｏａｄｌｅａｖｅｄＫｏｒｅａｎＰ...     

小兴安岭阔叶红松林地表甲虫Metacommunity格局

Metacommunity理论框架为理解生物群落的时空格局及其构建机制提供了一个强有力的方法。然而,少有研究揭示土壤动物metacommunity的格局及其构建机制,小尺度空间的研究更是少见。于2015年分别在凉水和丰林小兴安岭典型阔叶红松林长期动态监测样地内,通过空间直观定位调查监测的方法获得地表甲虫群落,揭示小尺度空间(300 m)地表甲虫metacommunity的格局,并进一步分析地形、土壤因子与这种metacommunity格局的相关性。结果表明:镶嵌型(nestedness)和随机型(random)是小尺度空间地表甲虫metacommunity的常见格局。地表甲虫的metacommunity格局具有类群依赖性,步行虫科和葬甲科多形成镶嵌型格局,而隐翅虫科则仅形成随机型格局。地表甲虫metacommunity格局具有季节波动性,在相对温暖的季节易形成显著的镶嵌型格局,而在相对寒冷的季节多为随机型格局。凉水和丰林地表甲虫的metacommunity格局没有明显差异。地形和土壤因子对地表甲虫metacommunity格局有重要的影响,该影响过程相对复杂,依类群和时间而异。本实验表明镶嵌型和随机型是小尺度空间小兴安岭典型阔叶红松林地表甲虫的常见格局,地形、土壤因子对这些格局的形成有重要的影响。     

Genetic Variation in Fragmented Forest Stands of the Andean Oak Quercus humboldtii Bonpl. (Fagaceae)1

Quercus humboldtii is a montane forest dominant species in Colombia, which has experienced significant habitat loss. Using three microsatellite loci, we compared the genetic diversity of adults and seedlings in fragments of small and large size. Results show high genetic diversity, comparable to other temperate oak species (H_o= 0.813, H_e= 0.780, and f=?0.044). However, allelic richness reduction in seedlings of the most fragmented part of the landscape, suggested restricted gene flow and risk of future genetic bottlenecks, if larger tracts of forest disappear.     

在韩国境内Potentilla fragarioides var .sprengeliana的遗传多样性和种群结构(英文)

根据 2 2个等位酶位点遗传变异 ,探讨了韩国境内委陵菜 (PotentillafragarioidesL .var.sprengeliana)的遗传多样性和种群结构。酶位点的多态位点百分比为 5 9 1%。种和种群水平上的遗传多样性比较高 ,分别为Hes=0 .2 10 ,Hep=0 .199;而种群的分化水平则相对较低 (GST=0 .0 74)。 19个种群中随机交配的偏差为FIS=0 .331。每代迁移数的间接估计 (Nm=3.15 )表明该种在韩国的种群间基因流较高。另外 ,固定指数分析显示在一些种群和位点有轻微的杂合子缺乏。种群间平均遗传一致度为 0 985。这些韩国委陵菜种群存在于较为均一的生境 ,这很有可能是造成其种群遗传一致性较高的原因。     

Patterns of Genetic Diversity and Population Structure of the Clonal Herb,Potentilla fragarioides var. sprengeliana (Rosaceae) in Korea

The genetic diversity and population structure of Potentilla fragarioides var. sprengeliana(Rosaceae) in Korea were investigated using genetic variation at 22 allozyme loci. The percent of polymorphic loci within the enzymes was 59.1%. The genetic diversity at the species level and at the population level was high (Hes=0.210; Hep=0.199, respectively), whereas the extent of the population divergence was relatively low (GST=0.074). FIS, a measure of the deviation from random mating within the 19 populations, was 0.331. An indirect estimate of the number of migrants per generation (Nm=3.15) indicates that gene flow is high among Korean populations of the species. In addition, analysis of fixation indices revealed a slight heterozygote deficiency in some populations and at some loci. The mean genetic identity between populations was 0.985. It is highly probable that the trend of genetic uniformity in a relatively homogeneous habitat is thought to be operated among Korean populations of P. fragarioides var.sprengeliana.     

Population genetic structure of the gynodioecious Thymus vulgaris L. (Labiatae) in southern France

In a self-compatible gynodioecious species, the abundance of female plants (which are obligate outcrossers) relative to hermaphrodites (which may self and outcross) may be a critical factor influencing genetic diversity and population structure. In the gynodioecious Thymus vulgaris L., female frequency varies from 5 to 95%, providing a suitable model to examine this issue. In this study, we use allozyme markers to (1) evaluate the relationship between female frequency, genetic diversity and population structure, (2) determine whether females and hermaphrodites vary in heterozygote deficiency and (3) examine whether other factors such as plant density are related to heterozygote deficiency. Twenty three natural populations, with female frequencies ranging from 11 to 92%, were sampled in and around the St-Martin-de-Londres basin in southern France. Based on four polymorphic allozyme loci, we found no significant correlation between female frequency and heterozygote deficiency. A significant (P < 0.05) F_IS value over loci and over populations of 0.11 was detected. The F_IS value per population showed a significant heterozygote deficiency in 11 of the 23 populations. However, no significant difference between female and hermaphrodite F_IS values was found. A significant heterozygote deficiency only occurred in populations of intermediate density. There was little differentiation among populations (F_ST = 0.038) nor among subpopulations within each population. The significant F_IS values are thus mostly due to inbreeding effects. The lack of a correlation between F_IS values and female frequency may be due to outcrossing in hermaphrodites and/or restoration of male fertility which may occur to a greater extent at low female frequency. The similarity of female and hermaphrodite F_IS values indicates that females may occasion high levels of biparental inbreeding.     

Population Structure and Growth Patterns of Opuntia echios var. gigantea along an Elevational Gradient in the Galípagos Islands1

Cacti growing in forests potentially experience growth limitation due to reduced light availability. To test this hypothesis, we studied the population structure of Opuntia echios var. gigantea at 15 sites on the south side of Isla Santa Cruz, Galípagos Islands, Ecuador. Populations were located in communities ranging from arid scrub at low elevations to closed‐canopy tropical dry forest at higher elevations. Ordination confirmed the existence of a strong elevation‐vegetation gradient. Opuntia abundance peaked at lower elevations (ca 30 m), with lower densities in closed‐canopy sites. For populations in scrub vegetation, density declined fairly regularly with plant height. Populations in forested sites had few plants of intermediate height, suggesting periodic recruitment. Scrub populations had random dispersion, while those in forests were aggregated. The change in spatial pattern may be related to a change in primary reproductive mode from asexual propagation via fallen fruits to propagation via fallen cladodes. Height was significantly correlated with stem diameter. Intercepts of these relationships increased toward higher elevations, probably in response to the increasing height of the surrounding canopy.     

基于线粒体Cyt b序列对新疆额尔齐斯河贝加尔雅罗鱼遗传结构的分析

采用线粒体Cyt b基因序列对额尔齐斯河流域的青河(QH,18尾)、哈巴河(HBH,21尾)、185团(185T,18尾)和乌伦古湖(WLG,20尾)4个贝加尔雅罗鱼(Leuciscus leuciscus baicalensis)群体进行了遗传结构的比较分析。在片段长度为1 109 bp的同源序列上,77尾个体共检测到54种单倍型,其中共享单倍型7个,总单倍型多样性指数(Hd)、总核苷酸多样性指数(π)和平均核苷酸差异数(K)分别为0.981 9、0.008 21和9.091,且185团群体单倍型多样性指数和核苷酸多样性指数最高、青河群体最低。4个群体间遗传距离在0.006~0.011之间,基于Kimura 2-parameter法构建的单倍型邻接关系树分为3支,群体间遗传关系和地理分布没有明显的相关性。AMOVA分析显示额尔齐斯河流域贝加尔雅罗鱼遗传差异极显著(P0.01)。青河和乌伦古湖群体基因流(Nm)远高于其他群体间,推测乌伦古河或许是二者进行基因交流的渠道。尽管单倍型核苷酸不配对分布呈双峰,但偏差平方和(Q)与粗糙指数(r)均不显著(P0.05),且Tajima′s D和Fu′s Fs检验也均显著偏离中性,结合群体呈现高单倍型多样性和低核苷酸多样性的特点,推测贝加尔雅罗鱼经历了群体扩张事件。参考已校正的鲤科鱼类Cyt b基因0.76%/Ma的进化速率,估算群体扩张的时间大约在1.97 Ma前的更新世中晚期,推测该时期阿尔泰山地区发生的冰川作用和频繁的古地震造成的地理隔离和融合可能是贝加尔雅罗鱼发生群体扩张的重要原因。     

青海野生黄色类群羊肚菌群体遗传结构分析

为明确青海野生黄色类群羊肚菌群体的遗传结构和遗传多样性,本研究利用SSR分子标记对来自青海省3个地理单元7个地区的35株野生黄色类群羊肚菌进行分析.结果 显示,12对引物共扩增出54条清晰可识别条带,其中多态性条带有48条,占比88.8％.居群水平的Nei's遗传多样性指数和Shannon's多样性指数分别为0.371...     

Microsatellite DNA Population Structure and Stock Identification of Steelhead Trout (<Emphasis Type="BoldItalic">Oncorhynchus mykiss</Emphasis>) in the Nass and Skeena Rivers in Northern British Columbia

Population structure and the application to genetic stock identification for steelhead (Oncorhynchus mykiss) in the Nass and Skeena Rivers in northern British Columbia was examined using microsatellite markers. Variation at 8 microsatellite loci (Oki200, Omy77, Ots1, Ots3, Ssa85, Ots100, Ots103, and Ots108) was surveyed for approximately 930 steelhead from 7 populations in the Skeena River drainage and 850 steelhead from 10 populations in the Nass River drainage, as well as 1550 steelhead from test fisheries near the mouth of each river. Differentiation among populations within rivers accounted for about 1.9 times the variation observed among years within populations, with differences between drainages less than variation among populations within drainages. In the Nass River, winter-run populations formed a distinct group from the summer-run populations. Winter-run populations were not assessed in the Skeena River watershed. Simulated mixed-stock samples suggested that variation at the 8 microsatellite loci surveyed should provide relatively accurate and precise estimates of stock composition for fishery management applications within drainages. In the Skeena River drainage in 1998, Babine River (27%) and Bulkley drainage populations (31%) comprised the main components of the returns. For the Nass River in 1998 steelhead returning to Bell-Irving River were estimated to have comprised 39% of the fish sampled in the test fishery, with another 27% of the returns estimated to be derived from Cranberry River. The survey of microsatellite variation did not reveal enough differentiation between Nass River and Skeena River populations to be applied confidently in estimation of stock composition in marine fisheries at this time. Received January 14, 2000; accepted July 13, 2000.