刺五加种群生态学的研究 Ⅱ．刺五加的种群统计

在３种天然次生林类型中,以刺五加的无性系小株为统计单位,编制该种群的生命表,分析其种群动态．结果表明,刺五加种群有２个死亡率高峰,在不同的森林群落中其死亡强度有较明显差异．种群的总亏损度不同,这些都与群落生境有关．该种群的存活曲线趋近于ＤｅｅｖｅｙⅢ型．     

山西灵空山刺五加种群空间分布格局及种间空间关联性

以山西灵空山自然保护区刺五加(Acanthopanax senticosus(Rupr.Maxim.)Harms)种群为对象,采用空间点格局方法中的Ripley’s K函数,对刺五加种群不同龄级的空间分布格局及其与主要灌木物种间的空间关联性进行研究,并对种群空间分布格局进行可视化解析。结果显示,刺五加种群中幼年个体数量多,径级结构呈金字塔型,为增长型种群,能够实现持续更新;刺五加种群的径级Ⅰ在小尺度上呈聚集分布,随着尺度增大出现随机分布;径级Ⅱ、Ⅲ、Ⅳ在全尺度上呈聚集分布,径级Ⅴ、Ⅵ在小尺度上为聚集分布,随着龄级和空间尺度的增大,刺五加种群聚集强度渐弱,呈现随机分布;刺五加种内关联在全尺度上呈正相关,但与群落中主要灌木在小尺度上呈不相关或负相关,在大尺度上呈负相关。研究表明刺五加的生长条件较为适宜,并可以通过相互之间的庇护作用,减弱种内竞争,但与其他树种间存在强烈竞争,生存现状较差,在群落中处于劣势。     

采伐对红松种群结构与动态的影响

红松是我国长白山阔叶红松林的主要建群种,受森林采伐的影响,种群数量急剧下降,现已被列为国家二级保护植物。通过绘制种群静态生命表、生存函数、存活曲线和径级分布图,研究原始林,15%择伐、40%择伐和皆伐后恢复的天然次生林内,红松种群结构和动态的变化规律。结果表明:(1)采伐干扰对红松种群的波动周期影响不大,15%的择伐强度可以提高红松种群的生存期望。(2)原始林和15%择伐林内红松种群存活曲线均为DeeveyⅡ型,种群处于稳定期;40%择伐林内存活曲线介于DeeveyⅡ型和DeeveyⅢ型之间,种群由稳定期向成熟期过渡;皆伐林内存活曲线为DeeveyⅠ型,种群处在增长期。(3)原始阔叶红松林林、15%择伐林和40%择伐林内,红松种群径级结构均呈稳定的倒J型,且在幼树阶段均存在生长更新的停滞现象;与原始林相比,15%择伐林内幼树比例略有下降;40%择伐林和皆伐迹地,随采伐强度的增加,幼树比例明显增大。(4)方差分析表明,4个种群的生存过程差异较大,采伐干扰对红松种群生存过程的影响达到显著水平。     

人为干扰对闽北栲树和木荷种群的影响

对闽北森林群落中的栲树（Ｃａｓｔａｎｏｐｓｉｓｆａｒｇｅｓｉ）和木荷（Ｓｃｈｉｍａｓｕｐｅｒｂａ）种群的数量特征和等级度结构分析表明：栲树和木荷均是闽北阔叶林迹地上的建群种群。中等强度的人为干扰可促进栲树种群发展,缺乏干扰或强烈的人为干扰均产生抑制作用。木荷种群在受自然干扰的森林群落中相对稳定,重要值和高等级度比例增加,而人为干扰使木荷种群减小,低等级度比例增加。人为干扰强度越大,木荷种群越难以发展。     

雾灵山落叶阔叶林采伐迹地物种多样性和植物种群动态变化研究

在对永久样地连续５ 年定位观测的基础上,应用Ｓｈａｎｎｏｎ 物种多样性和均匀度指数,研究了雾灵山落叶阔叶林采伐前后更新苗木、草本植物和灌木群落的物种多样性、群落均匀度和种群动态变化．结果表明,在林分采伐后的４ 年内,迹地上苗木的物种多样性和群落均匀度指数均高于伐前林分．从无到有并迅速繁衍的树种为山杨,伐前林分中有林木存在,但迹地上缺乏幼苗的树种为油松．灌木的物种多样性和均匀度指数呈增加趋势．始终处于优势的树种为锦带花和胡枝子,后期迅速繁衍的树种为山楂叶悬钩子．草本植物的物种多样性和群落均匀度指数均是在林分采伐后第３ 年达到最大值,第４ 年开始下降．主要草本植物种群的动态变化可归纳为８ 种类型．阳性植物充分发育,阴性或耐荫植物逐渐衰退,是草本植物种群最明显的表现．     

不同生境下刺五加种群构件生物量结构与生长规律

从构件水平对针阔混交林、蒙古栎林和次生杂木林3个生境的刺五加种群各功能构件的生物量结构及生物量比率与年龄之间的关系进行了定量分析. 结果表明,刺五加种群的个体生长和各构件生物量动态与环境条件关系密切.不同环境条件下,刺五加种群各功能构件生物量平均值具有相同的规律：茎构件>根茎构件>叶构件.3个生境中刺五加整体种群水平具有一定的相似性.在郁闭度为40%的蒙古栎林中,刺五加种群个体生物量和各构件生物量较针阔混交林和次生杂木林中大.不同生境下刺五加种群分株生物量的差异蕴涵着重要的生长调节和物质分配策略.在分株较小的幼龄个体以及郁闭度较大而不利于分株生长的次生杂木林中,分株优先建造叶器官,以保证充分的物质生产. 3个生境刺五加种群的叶、茎与分株的相对增重均具有相同的幂函数异速生长规律.     

云南兰坪云南红豆杉种群年龄结构与空间分布格局分析

利用点格局分析法对滇西北兰坪县4个云南红豆杉(Taxus yunnanensis)种群的年龄结构、不同生长阶段空间分布格局及其关联性进行分析。结果表明:(1)林窗与人为干扰影响4个云南红豆杉种群的龄级结构,小林窗的种群呈稳定型;较大林窗的种群呈进展型;群落结构完整未出现林窗和有较大人为干扰的种群年龄结构均呈衰退型,幼苗、幼树与小树个体缺乏,种群存在一定程度的更新困难,林窗的大小是种群更新的重要因素。(2)人为干扰、自然生境与本身生物学特性影响4个种群空间分布格局,种群1整体及其不同生长阶段个体均呈聚集分布;种群2和种群4在小尺度呈聚集分布,而在大尺度上呈随机分布;种群3随着空间尺度增大分布格局表现为聚集→随机→聚集趋势。(3)种群2中幼苗、小树和中树在小尺度下表现为聚集分布,其他尺度下表现为随机分布;种群3的小树阶段聚集分布和随机分布皆有出现,中树与大树在不同尺度上表现为聚集分布;种群4聚集分布的强度随生长阶段的增加在减弱。(4)4个种群各发育阶段间皆呈或接近显著正相关,种内竞争弱,有利于种群维持。     

重度砍伐后极小种群野生植物崖柏群落结构动态

砍伐导致濒危植物种群个体数量减少, 群落结构改变, 加剧物种灭绝风险。崖柏(Thuja sutchuenensis)为典型极小种群野生植物, 森林砍伐是导致其种群数量急剧下降的主要原因。但是, 到目前为止, 有关崖柏种群及其群落对砍伐的响应鲜有报道。本研究以重度砍伐后的崖柏群落为研究对象, 基于对崖柏群落固定样地的调查和两次复查, 对比分析了伐后崖柏种群径级结构、种群生存力、物种多样性及其群落结构动态等特征。结果表明: 崖柏残存群落伐后13年崖柏种群个体数量增加了22.58%, 其中幼苗幼树占85.71%, 而崖柏种群生存率下降25.43%, 种群死亡密度和危险率分别增加了24.12%和28.62%。崖柏群落物种丰富度和Shannon-Wiener指数分别增加96.43%和33.35%。研究结果表明, 砍伐使崖柏种群生存力及其在群落中的优势度持续下降, 崖柏占优势的针阔混交林有向阔叶林演替的趋势, 崖柏种群受到严重威胁, 亟需采取紧急保护措施。     

不同生境刺五加生长发育及光合特性研究

以郁闭度分别为40%、60%和70%的蒙古栎林、针阔混交林和次生杂木林3种生境下野生刺五加种群为材料,考察了其生长发育、光合色素和光合特性的变化,探讨刺五加种群对光照条件的适应机制,寻找有利于刺五加种群生长和更新的适宜天然条件,为人工抚育生境的选择和促进天然次生林更新提供科学依据.结果表明:(1)不同生境下刺五加种群个体株高、基径和生物量均表现为蒙古栎林>针阔混交林>次生杂木林;随着郁闭度的增加,刺五加种群叶构件生物量比率呈现增加的趋势,而茎构件和根茎构件生物量比率则呈现下降的趋势.(2)刺五加种群叶绿素a、叶绿素b、类胡萝卜素含量随着生境郁闭度增加呈逐渐增加趋势,而叶绿素a/b却呈下降趋势.(3)随着郁闭度的增加,刺五加种群的净光合速率、气孔导度、蒸腾速率、水分利用效率、气孔限制值、光饱和点、光补偿点和暗呼吸速率等光合参数均显著降低,而胞间二氧化碳浓度却显著提高.(4)蒙古栎林下刺五加种群具有相对较高的净光合速率和水分利用效率,从而带动种群各构件旺盛生长,使其个体株高、基径、各功能构件生物量均显著高于针阔混交林和次生杂木林种群;光能不足是限制次生杂木林刺五加种群生长的主要因子之一.因此,在抚育刺五加人工林的过程中,应该充分考虑郁闭度对刺五加种群生长发育的影响,同时还要考虑其他植物对刺五加种群生态位的竞争,并以在郁闭度40%的蒙古栎林下抚育为佳.     

矮牡丹种群结构的研究

延安万花山不同生境下矮牡丹种群年龄结构与表现结构的分析结果表明：天然侧柏林缘下的矮牡丹种群属稳定发展的种群,其动态符合负指数方程Ｎ＝１７７４。０１４,ｅ＾－０．１３７５ｔ。而在较郁闭的辽东栎林下,矮牡丹种群呈阶段性更新循环。种群平均密度和单株最大年龄与所处生境有关。种群的表现结构因样地所在的环境条件不同,种群的年龄结构不同,以及生长速度的不同而有较明显的差异。     

刺五加的有性生殖与营养繁殖

刺五加 Eleutherococcus senticosus (Rupr.et Maxim.)Maxim,既可进行有性繁殖,又可进行营养繁殖。本文报道其三类花丝长度不同的植株每个花序的花朵数量、座果率、饱满种子率及根茎形态和形态发生的某些特点。通过人工受精,检测了其繁育系统。结果表明:长花丝植株不座果,短花丝植株座果,但不同年份、不同生境中座果率不同,中花丝植株也座果但饱满种子率教低。在正常年份,短花丝植株的座果率接近40％,并且林缘的座果率稍高于皆伐迹地和次生林下的。考虑到中花丝植株在所研究地区居群数很少,我们认为绝大多数刺五加种子是异花传粉的产物,其有性生殖与营养繁殖相配合,在无人为破坏的前提下,该物种不应该濒危。     

Millipede communities in rehabilitating coastal dune forests in northern KwaZulu/Natal, South Africa

The rehabilitation, after mining, of coastal sand dunes north of Richards Bay by Richards Bay Minerals began some 18 years ago, and resulted in the simultaneous availability of a known-aged series of stands representative of coastal dune forest succession.
A survey of the millipede community in this area revealed increases in species diversity and a decrease in their density, with an increase in stand age. Development of these communities is characterized by replacement and addition of species, typical of ecological succession. Colonization of areas disturbed by mining reflects on the species reservoir present in the surrounding unmined forests with apparent pioneer species being either replaced or complemented by the relatively slow invasion of secondary species.
Comparisons of age-specific millipede community variables on rehabilitating dunes with those recorded in relatively undisturbed dunes suggest that the development of communities results from autogenic succession initiated through habitat rehabilitation. With several community parameters in rehabilitating dune forests being similar to those recorded in undisturbed forests, it is concluded that the millipede community can be restored through management options based on principles relating to ecological succession.     

云南橡胶林和天然次生林枯落物层蚂蚁物种多样性、群落结构差异及指示种

橡胶树Hevea brasiliensis是云南省重要的经济林木, 但对其生态服务功能尚存在争议。本研究以天然次生林为对照, 使用Winkler法对橡胶林枯落物层蚂蚁进行初步研究, 探讨橡胶林枯落物层蚂蚁的生态状况。于2012年10月和2013年4月采用Winkler袋法调查了云南省绿春县大黑山乡橡胶林和牛孔乡天然次生林枯落物层蚂蚁群落的物种多样性、 群落结构差异及指示种。结果表明： 橡胶林枯落物层蚂蚁多度（转换后）、 物种丰富度S和ACE值显著低于无干扰的天然次生林（P<0.05）; 蚂蚁多度（转换后）显著低于有干扰的天然次生林（P<0.05）, 而物种丰富度S和ACE值差异不显著。橡胶林枯落物层蚂蚁群落结构与两种天然次生林都不相似（F=3.93, df=12, P<0.01）。橡胶林中流浪种大头蚁属Pheidole的蚂蚁种类与天然次生林相比, 物种丰富度增加了100%。天然次生林枯落物层中蚂蚁指示种有3种, 分别为刘氏隆头蚁Strumigenys lewisi、 黄足厚结猛蚁Pachycondyla luteipes和女娲角腹蚁Recurvidris nuwa, 而橡胶林枯落物层中指示种仅为菱结大头蚁Pheidole nodus。枯落物层蚂蚁物种多样性与枯落物厚度呈显著正相关, 而枯落物盖度仅与蚂蚁多度（转换后）有相关性。结果说明, 橡胶林经过长期的经营管理, 生态环境趋于稳定, 对枯落物层蚂蚁群落具有一定的保护作用, 但与天然次生林相比, 蚂蚁多度（转换后）及群落结构仍显示出明显的不同。     

Species Richness,Forest Structure,and Functional Diversity During Succession in the New Guinea Lowlands

Much of the world's tropical forests have been affected by anthropogenic disturbance. These forests are important biodiversity reservoirs whose diversity, structure and function must be characterized across the successional sequence. We examined changes in structure and diversity along a successional gradient in the lowlands of New Guinea. To do this, we measured and identified all stems ≥5 cm diameter in 19 0.25 ha plots ranging in age from 3 to >50 yr since disturbance. We also measured plant functional traits related to establishment, performance, and competitive ability. In addition, we examined change in forest structure, composition, species diversity, and functional diversity through succession. By using rarefaction to estimate functional diversity, we compared changes in functional diversity while controlling for associated differences in stem and species density. Basal area and species density increased with stand age while stem density was highest in intermediate secondary forests. Species composition differed strongly between mature and secondary forests. As forests increased in basal area, community‐weighted mean wood density and foliar carbon increased, whereas specific leaf area and proportion of stems with exudate decreased. Foliar nitrogen peaked in medium‐aged forests. Functional diversity was highest in mature forests, even after accounting for differences in stem and species diversity. Our study represents one of the first attempts to document successional changes in New Guinea's lowland forest. We found robust evidence that as succession proceeds, communities occupy a greater range of functional trait space even after controlling for stem and species density. High functional diversity is important for ecological resiliency in the face of global change.     

Area and Age of Secondary Forests in Brazilian Amazonia 1978–2002: An Empirical Estimate

In quantifying the carbon budget of the Amazon region, temporal estimates of the extent and age of regenerating tropical forests are fundamental. However, retrieving such information from remote-sensing data is difficult, largely because of spectral similarities between different successional stages and variations in the reflectance of forests following different pathways of regeneration. In this study, secondary-forest dynamics in Brazilian Amazonia were modeled for the 1978–2002 period to determine area and age on a grid basis. We modeled the area, age, and age class distribution of secondary forests using empirical relationships with the percentage of remaining primary forest, as determined from large-area remote-sensing campaigns (the Pathfinder and Prodes projects). The statistical models were calibrated using detailed maps of secondary-forest age generated for seven sites in the Brazilian Legal Amazon. The area–age distribution was then specified from mean age by a distribution assumption. Over the period 1978–2002, secondary-forest area was shown to have increased from 29,000 to 161,000 km² (that is, by a factor of 5). The mean age increased from 4.4 to 4.8 years. We generated a time series of secondary-forest area fractions and successional stages that provides wall-to-wall coverage of the Brazilian Amazon at a spatial resolution of 0.1 decimal degrees (approximately 11 km). Validation against reference data yielded root mean squared errors of 8% of the total area for estimate of secondary-forest area and 2.4 years for mean secondary-forest age. Using this approach, we provide the first published update on the state of secondary forests in Amazonia since the early 1990s and a time series of secondary-forest area over the 25-year period.     

辽东山区次生林木本植物空间分布

森林木本植物的空间格局有助于揭示群落结构的形成机制与潜在的生态学过程,且对林分经营具有一定指导意义。在0—50 m尺度范围内综合分析了辽东山区4 hm2温带次生林样地多度10的树种空间格局。研究发现:(1)在完全随机零模型下,大部分树种呈现聚集格局,聚集格局树种的比例随尺度增加而降低;在32 m的较大尺度下,随尺度增加,随机和规则格局成为树种分布的主要形式;(2)在异质性泊松过程零模型下,55.9%的树种呈现随机格局,其余大部分树种在10 m的尺度下呈现聚集格局,且随尺度增加,规则格局成为主要形式;(3)在完全随机零模型下,树种属性(林层、径级和多度)显著地影响种群聚集度,而在异质性泊松过程零模型下,树种属性对种群聚集度不存在显著影响。综上,生境异质性、扩散限制和树种属性部分解释了辽东山区次生林木本植物空间分布格局,相对而言,生境异质性的效应更为突出。研究结果有助于揭示次生林群落生物多样性的维持机制。     

Comprehensive Conservation Profile of Tana Mangabeys

Forests along 60 kilometers of the lower Tana River, Kenya, provide habitat for one of the world’s top 25 most endangered primates, the Tana mangabey (Cercocebus galeritus). There is no current accurate estimate of the mangabey population, but a 1994 census estimated the population at 1,000–1,200. Their habitat has been severely degraded since then: visual estimates indicated that 30% of the forest area has been cleared and product use has increased in > 80% of forests surveyed. As the mean number of mangabey groups per forest is positively correlated with forest area and density of trees, this loss is damaging to the mangabey population. There has also been an increase in mangabey-human conflict, e.g., crop raiding, set traps, mangabeys chased by dogs. Mangabeys exhibit ecological flexibility, but behavioral data come from only a few mangabey groups. A new conservation approach is needed because past approaches, particularly the Tana River Primate National Reserve and a World Bank/Global Environment Facility Project, failed to protect the forests. The failure was mainly due to a disregard of the land-tenure issue within the Reserve, exclusion of local people from decision-making, and neglect of forests outside the reserve. Future actions must include community conservation programs and forest and corridor restoration. Research should focus on traditional management, status of primate groups in severely degraded forests, ecology of additional groups, and a population estimate to inform management as they implement more specific conservation strategies for the species.     

High compatibility between arbuscular mycorrhizal fungal communities and seedlings of different land use types in a tropical dry ecosystem

We conducted this study to explore limitations for the establishment of mycorrhizal associations in disturbed areas of the tropical dry ecosystem in the Chamela region of Jalisco, Mexico. Specifically, we: (1) assessed the diversity and composition of arbuscular mycorrhizal fungal (AMF) communities through spore morphospecies identification in three common land uses (primary forest, secondary forest, and pasture), (2) tested the inoculum potential of the AMF communities and the effect of water stress on the establishment of mycorrhizal associations in seedlings of various plant species, and (3) explored the importance of AMF community composition on early seedling development. Soil and root samples were taken from 15 random points in each of three plots established in two primary forests, two 26-year-old secondary forests, and two 26-year-old pastures. We expected that because of soil degradation and management, pastures would have the lowest and primary forests the highest AMF species richness. We found evidence for changes in AMF species composition due to land use and for higher morphospecies richness in primary forests than in secondary forests and pastures. We expected also that water stress limited plant and mycorrhizal development and that plants and AMF communities from secondary forests and pastures would be less affected by (better adapted to) water stress than those from the primary forest. We found that although all plant species showed biomass reductions under water stress, only some of the plant species had lower mycorrhizal development under water stress, and this was regardless of the AMF community inoculated. The third hypothesis was that plant species common to all land use types would respond similarly to all AMF communities, whereas plant species found mainly in one land use type would grow better when inoculated with the AMF community of that specific land use type. All plant species were however equally responsive to the three AMF communities inoculated, indicating that all plants established functionally compatible AMF in each community, with no preferences. The results suggest that early seedling growth and mycorrhizal development in secondary forests and pastures is not likely limited by diversity, quantity, or quality of mycorrhizal propagules but by the high temperature and water stress conditions prevailing at those sites.