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1.
Understanding how communities respond to environmental gradients is critical to predict responses of species to changing habitat conditions such as in regenerating secondary habitats after human land use. In this study, ground-living ants were sampled with pitfall traps in 27 plots in a heterogeneous and diverse subtropical forest to test if and how a broad set of environmental variables including elevation, successional age, and tree species richness influence ant diversity and community composition. In total, 13,441 ant individuals belonging to 71 species were found. Ant abundance was unrelated to all environmental variables. Rarefied ant species richness was negatively related to elevation, and Shannon diversity decreased with shrub cover. There was considerable variation in ant species amongst plots, associated with elevation, successional age, and variables related to succession such as shrub cover. It is shown that younger secondary forests may support a species-rich and diverse community of ants in subtropical forests even though the species composition between younger and older forests is markedly different. These findings confirm the conservation value of secondary subtropical forests, which is critical because subtropical forests have been heavily exploited by human activities globally. However, the findings also confirm that old-growth forest should have priority in conservation as it supports a distinct ant community. Our study identifies a set of ant species which are associated with successional age and may thus potentially assist local conservation planning.  相似文献   

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Question: Knowledge of the interaction between understorey herb and overstorey tree layer diversity is mostly restricted to temperate forests. How do tree layer diversity and environmental variables affect herb layer attributes in subtropical forests and do these relationships change in the course of succession? Do abundance and diversity of woody saplings within the herb layer shift during succession? Location: Subtropical broad‐leaved forests in southeast China (29°8′18″‐29°17′29″N, 118°2′14″118°11′12″E). Methods: A full inventory of the herb layer including all plants below 1‐m height was done in 27 plots (10 × 10 m) from five successional stages (<20, <40, <60, <80 and ≥80 yr). We quantified the contribution of different life forms (herbaceous, woody and climber species) to herb layer diversity and productivity and analysed effects of environmental variables and tree layer diversity on these attributes. Results: Herb layer composition followed a successional gradient, as revealed by non‐metric multidimensional scaling (NMDS), but diversity was not correlated to the successional gradient. There was no correlation of diversity across layers. Herb layer productivity was neither affected by tree layer diversity nor by herb layer diversity. Although abundance of woody species in the herb layer decreased significantly during succession, woody species contributed extraordinarily to herb layer species diversity in all successional stages. All environmental factors considered had little impact on herb layer attributes. Conclusions: The subtropical forest investigated displays an immense richness of woody species in the herb layer while herbaceous species are less prominent. Species composition of the herb layer shows a clear successional pattern, however, the presence or absence of certain species appears to be random.  相似文献   

4.
Differences in herbivory among woody species can greatly affect the functioning of forest ecosystems, particularly in species-rich (sub)tropical regions. However, the relative importance of the different plant traits which determine herbivore damage remains unclear. Defence traits can have strong effects on herbivory, but rarely studied geographical range characteristics could complement these effects through evolutionary associations with herbivores. Herein, we use a large number of morphological, chemical, phylogenetic and biogeographical characteristics to analyse interspecific differences in herbivory on tree saplings in subtropical China. Unexpectedly, we found no significant effects of chemical defence traits. Rather, herbivory was related to the plants' leaf morphology, local abundance and climatic niche characteristics, which together explained 70% of the interspecific variation in herbivory in phylogenetic regression. Our study indicates that besides defence traits and apparency to herbivores, previously neglected measures of large-scale geographical host distribution are important factors influencing local herbivory patterns among plant species.  相似文献   

5.
The high tree diversity of subtropical forests is linked to the biodiversity of other trophic levels. Disentangling the effects of tree species richness and composition, forest age, and stand structure on higher trophic levels in a forest landscape is important for understanding the factors that promote biodiversity and ecosystem functioning. Using a plot network spanning gradients of tree diversity and secondary succession in subtropical forest, we tested the effects of tree community characteristics (species richness and composition) and forest succession (stand age) on arthropod community characteristics (morphotype diversity, abundance and composition) of four arthropod functional groups. We posit that these gradients differentially affect the arthropod functional groups, which mediates the diversity, composition, and abundance of arthropods in subtropical forests. We found that herbivore richness was positively related to tree species richness. Furthermore, the composition of herbivore communities was associated with tree species composition. In contrast, detritivore richness and composition was associated with stand age instead of tree diversity. Predator and pollinator richness and abundance were not strongly related to either gradient, although positive trends with tree species richness were found for predators. The weaker effect of tree diversity on predators suggests a cascading diversity effect from trees to herbivores to predators. Our results suggest that arthropod diversity in a subtropical forest reflects the net outcome of complex interactions among variables associated with tree diversity and stand age. Despite this complexity, there are clear linkages between the overall richness and composition of tree and arthropod communities, in particular herbivores, demonstrating that these trophic levels directly impact each other.  相似文献   

6.
From regional to global scales, anthropogenic environmental change is causing biodiversity loss and reducing ecosystem functionality. Previous studies have investigated the relationship between plant diversity and functional insect communities in temperate and also in tropical grasslands and forests. However, few studies have explored these dynamics in subtropical forests. Here, cavity-nesting Hymenoptera and associated parasitoids were collected across a controlled tree diversity experiment in subtropical China to test how predatory wasps, bees and parasitoids respond to tree species richness. Abundance and species richness of predatory wasps and parasitoids were positively correlated with tree species richness, while bee abundance and bee species richness were unrelated to tree species richness. Our results indicate that tree species richness increases the abundance and species richness of important communities such as predators and parasitoids. Moreover, the results highlight the importance of subtropical forests in maintaining abundance and species richness of key functional insect groups.  相似文献   

7.
Aim  This research aims to understand the factors that shape elevational diversity gradients and how those factors vary with spatial grain. Specifically, we test the predictions of the species–productivity hypothesis, species–temperature hypothesis, the metabolic theory of ecology and the mid-domain effects null model. We also examine how the effects of productivity and temperature on richness depend on spatial grain.
Location  Deciduous forests along an elevational gradient in Great Smoky Mountains National Park, USA.
Methods  We sampled 22 leaf litter ant assemblages at three spatial grains, from 1-m2 quadrats to 50 × 50 m plots using Winkler samplers.
Results  Across spatial grains, warmer sites had more species than did cooler sites, and primary productivity did not predict ant species richness. We found some support for the predictions of the metabolic theory of ecology, but no support for the mid-domain effects null model. Thus, our data are best explained by some version of a species–temperature hypothesis.
Main conclusions  Our results suggest that temperature indirectly affects ant species diversity across spatial grains, perhaps by limiting access to resources. Warmer sites support more species because they support more individuals, thereby reducing the probability of local extinction. Many of our results from this elevational gradient agree with studies at more global scales, suggesting that some mechanisms shaping ant diversity gradients are common across scales.  相似文献   

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苏日古嘎  张金屯  王永霞 《生态学报》2013,33(11):3394-3403
物种多样性是群落结构和功能复杂性的一种度量,物种多样性的空间分布格局受许多环境因子的影响.运用多样性指数,多层感知器网络,分析了松山保护区森林群落物种多样性与群落类型、结构和生境之间的关系.结果表明:(1)大果榆+山杨混交林、油松+青杨混交林物种丰富度、多样性和均匀度均较高,而大果榆林、华北落叶松林的各项指数值均较低.Patrick指数和Shannon-Weiner指数在森林群落中均表现为草本层>灌木层>乔木层;Pielou指数在榆林中表现为草本层>乔木层>灌木层,而在其他森林群落中表现为灌木层>草本层>乔木层.(2)功能层物种多样性在海拔梯度上的变化趋势不同,在乔木层,丰富度、多样性和均匀度随海拔的升高逐渐降低;在灌木层,丰富度、多样性和均匀度均呈比较明显的单峰曲线变化趋势;在草本层,丰富度和多样性随海拔的升高都呈下降趋势,而在草本层,均匀度变化不大.(3)用多层感知器网络预测功能层多样性效果很好,结果发现坡向对乔木层和灌木层物种多样性的影响最大,而海拔高度对草本层物种多样性的影响最大.  相似文献   

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古田山常绿阔叶林主要树种2002-2007年间更新动态   总被引:3,自引:0,他引:3  
种群更新是森林发育和演替过程中的重要环节.为了解古田山常绿阔叶林主要树种的更新动态,本研究以古田山自然保护区5 ha常绿阔叶林动态样地为对象,在对胸径(DBH)≥1 cm的木本植物个体2002年和2007年两次每木调查的基础上,比较主要树种的补员(recruitment)和死亡状况,分析种群大小变化趋势,研究了群落中主要木本植物的更新特点.结果表明:(1)5年间样地内木本植物个体从13,338株增长到16,812株,增幅达26.05%.新增4,758株胸径≥1 cm的补员个体,同时死亡1,384株.(2)乔木、小乔木或灌木、小灌木3种生长型的补员个体数目均随径级的增大而下降,但死亡个体却表现出不同的径级分布特点.(3)43个主要树种的平均年死亡率和年补员率分别为2.26%和5.90%.其中,19种小乔木或灌木在径级Ⅰ(1 cm≤DBH<2.5 cm)的补员率均高于死亡率,但径级Ⅱ(2.5cm≤DBH<5 cm)、径级Ⅲ(DBH≥5 cm)的补员率均和死亡率差别不大:而24种乔木各径级死亡率和补员率的关系则相对复杂.(4)43个主要树种中有31个为增长型种群,其余12个呈小幅度负增长.10个种群大小变化率在5%以上,属于快速变动的种群,其中以柳叶蜡梅(Chimonanthus salicifolius)(45.13%)和矩形叶鼠刺(Itea oblonga)(16.35%)的增幅最大,橙木(Loropetalum chinense)(-3.10%)和短柄袍(Quercus serrata vat.brevipetiolata)(-1.86%)的降幅最大.研究发现,3种生长型中,不同物种及其各个径级的补员率和死亡率各异,种群更新动态也有所差别,我们推测与密度制约和牛境波动有关.  相似文献   

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From regional to global scales, anthropogenic environmental change is causing biodiversity loss and reducing ecosystem functionality. Previous studies have investigated the relationship between plant diversity and functional insect communities in temperate and also in tropical grasslands and forests. However, few studies have explored these dynamics in subtropical forests. Here, cavity-nesting Hymenoptera and associated parasitoids were collected across a controlled tree diversity experiment in subtropical China to test how predatory wasps, bees and parasitoids respond to tree species richness. Abundance and species richness of predatory wasps and parasitoids were positively correlated with tree species richness, while bee abundance and bee species richness were unrelated to tree species richness. Our results indicate that tree species richness increases the abundance and species richness of important communities such as predators and parasitoids. Moreover, the results highlight the importance of subtropical forests in maintaining abundance and species richness of key functional insect groups.  相似文献   

11.
Aims The dispersal of pollen and seeds is spatially restricted and may vary among plant populations because of varying biotic interactions, population histories or abiotic conditions. Because gene dispersal is spatially restricted, it will eventually result in the development of spatial genetic structure (SGS), which in turn can allow insights into gene dispersal processes. Here, we assessed the effect of habitat characteristics like population density and community structure on small-scale SGS and estimate historical gene dispersal at different spatial scales.Methods In a set of 12 populations of the subtropical understory shrub Ardisia crenata, we assessed genetic variation at 7 microsatellite loci within and among populations. We investigated small-scale genetic structure with spatial genetic autocorrelation statistics and heterogeneity tests and estimated gene dispersal distances based on population differentiation and on within-population SGS. SGS was related to habitat characteristics by multiple regression.Important findings The populations showed high genetic diversity (H e = 0.64) within populations and rather strong genetic differentiation (F ′ ST = 0.208) among populations, following an isolation-by-distance pattern, which suggests that populations are in gene flow–drift equilibrium. Significant SGS was present within populations (mean Sp = 0.027). Population density and species diversity had a joint effect on SGS with low population density and high species diversity leading to stronger small-scale SGS. Estimates of historical gene dispersal from between-population differentiation and from within-population SGS resulted in similar values between 4.8 and 22.9 m. The results indicate that local-ranged pollen dispersal and inefficient long-distance seed dispersal, both affected by population density and species diversity, contributed to the genetic population structure of the species. We suggest that SGS in shrubs is more similar to that of herbs than to trees and that in communities with high species diversity gene flow is more restricted than at low species diversity. This may represent a process that retards the development of a positive species diversity–genetic diversity relationship.  相似文献   

12.
  1. Soil C is the largest C pool in forest ecosystems that contributes to C sequestration and mitigates climate change. Tree diversity enhances forest productivity, so diversifying the tree species composition, notably in managed forests, could increase the quantity of organic matter being transferred to soils and alter other soil properties relevant to the C cycle.
  2. A ten‐year‐old tree diversity experiment was used to study the effects of tree identity and diversity (functional and taxonomic) on soils. Surface (0–10 cm) mineral soil was repeatedly measured for soil C concentration, C:N ratio, pH, moisture, and temperature in twenty‐four tree species mixtures and twelve corresponding monocultures (replicated in four blocks).
  3. Soil pH, moisture, and temperature responded to tree diversity and identity. Greater productivity in above‐ and below‐ground tree components did not increase soil C concentration. Soil pH increased and soil moisture decreased with functional diversity, more specifically, when species had different growth strategies and shade tolerances. Functional identity affected soil moisture and temperature, such that tree communities with more slow‐growing and shade‐tolerant species had greater soil moisture and temperature. Higher temperature was measured in communities with broadleaf‐deciduous species compared to communities with coniferous‐evergreen species.
  4. We conclude that long‐term soil C cycling in forest plantations will likely respond to changes in soil pH, moisture, and temperature that is mediated by tree species composition, since tree species affect these soil properties through their litter quality, water uptake, and physical control of soil microclimates.
  相似文献   

13.
In species‐rich ecosystems, such as subtropical and tropical forests, higher trophic level interactions are key mediators of ecosystem functioning. Plant species loss may alter these interactions, but the effects of plant diversity might be modified by intraguild interactions, particularly among predators. We analyzed the relationships between spiders and ants, two dominant predatory arthropod taxa, on tree saplings across a gradient from medium to high woody plant species richness in a subtropical forest in Southeast China. Neither ant nor spider total biomass was significantly related to plant species richness. By contrast, the biomass distribution of web‐building and hunting spiders changed and spider family richness increased in the presence of ants, resulting in more web builder‐dominated assemblages. However, these relationships depended on the plant communities, and were stronger in plots with higher plant species richness. Our results indicate that in addition to potential effects of ants on hunting spiders in particular, ants could indirectly influence intraguild interactions within spider assemblages. The observed shifts in the spider assemblages with increasing ant presence and plant species richness may have functional consequences, as web‐building and hunting spiders have distinct prey spectra. The relationships among ants, spiders, and plant species richness might contribute to explaining the non‐significant relationship between the overall effects of predators and plant diversity previously observed in the same forest plots. Our findings thus give insight into the complexity of biotic interactions in such species‐rich ecosystems.  相似文献   

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中国西南喀斯特森林树种对土壤微生物群落多样性和生物量的影响陆地生态系统中植物种对土壤微生物群落结构的影响不一,而喀斯特生态系统中植物种对土壤微生物群落结构影响的研究尚未见报道。本研究利用磷酸脂肪酸(PLFA)法,分析了黔中高原型喀斯特常绿落叶阔叶混交林5个优势树种—窄叶石栎(Lithocarpus confinis Huang)、圆果化香(Platycarya longipes Wu)、滇鼠刺(Itea yunnanensis Franch.)、安顺润楠(Machilus cavaleriei H. Lév.)、云贵鹅耳枥(Carpinus pubescens Burkill)—与土壤理化性质对土壤微生物群落组成和生物量的影响。在测试的212个土壤样品 中共检测出132种PLFA,每个样品土壤微生物平均PLFA数量和生物量分别为65.97和11.22 µg g–1。土壤表层(0–10 cm)的土壤微生物PLFA数量与下层(10–20 cm)土壤接近,但前者土壤微生物生物量显著高于后者(P < 0.05)。树种影响土壤微生物PLFA数量,但对土壤微生物生物量没有影响。云贵鹅耳枥附近的土壤微生物PLFA数量显著高于其他树种(P < 0.05),而其他树种土壤微生物PLFA数量接近。土壤微生物 生物量与表层土壤的理化性质无显著相关,但与下层土壤的有机碳、全氮和全磷含量呈显著正相关 (P < 0.05)。总之,黔中高原型喀斯特森林真菌/细菌生物量比率低,微生物总生物量低,但微生物群落多样性高。树种对土壤微生物群落多样性产生影响。  相似文献   

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参照CTFS技术标准在鹞落坪国家级自然保护区(以下简称鹞落坪自然保护区)建立11.56 hm~2动态监测样地,以鹞落坪自然保护区落叶阔叶林乔木树种为研究对象,探讨其区系组成、种群结构、物种多样性以及优势种种间联结性。结果表明:(1)样地内胸径≥1 cm的乔木共有24910株,分属于35科、57属、103种;优势科为蔷薇科、槭树科、冬青科、樟科、杜鹃花科、虎耳草科、桦木科、壳斗科;(2)样地内乔木树种分布相对均匀,主要优势树种为茅栗、鹅耳枥、白檀和四照花;乔木树种在各个高度均有分布,但主要集中在2—8 m之间;(3)χ~2检验结果显示,样地内15个优势种105个树种对中仅有32个树种对之间存在显著的相关性,说明群落种间关联较弱。从联结系数(AC)来看,105个树种对中呈现显著正关联的树种对占42.9%,显著负关联的树种对占24.8%,但关联强度大部分集中在相对较低的水平,表明该地区群落结构整体仍处于发育阶段。  相似文献   

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宝天曼落叶阔叶林土壤细菌多样性   总被引:2,自引:0,他引:2  
土壤微生物在森林生态系统中起着重要作用。高通量测序方法的出现为进一步认识土壤微生物提供了契机。本文利用Illumina Miseq高通量测序技术对宝天曼森林土壤的细菌多样性进行了初步研究。结果显示: 在31个采样点内, 随着采样点增加, 检测出不同分类水平的土壤细菌类群也在增多, 当采样点达到31个时, 检测出的土壤细菌类群达到45门163纲319目495科785属和42,632个OTU; 31个土壤样品中所检测出的细菌类群平均有34.2门114.7纲215.2目323.7科446.6属5,924.7个OTU, 其中门、纲、目分类水平上的优势类群(所占比例)分别为变形菌门(Proteobacteria)(38.30%)、α-变形菌纲(α-Proteobacteria)(18.08%)、根瘤菌目(Rhizobiales)(10.62%)。这些初步研究结果表明在一定程度上宝天曼森林土壤有较高的细菌多样性水平, 为进一步认识森林土壤细菌多样性与植物多样性关系等奠定了基础。  相似文献   

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借鉴近自然森林管理理念,用阔叶林或针阔混交林替代南亚热带大面积人工针叶纯林已被认为是一种有效的森林培育方式.1993年,在位于广西凭祥的中国林业科学研究院热带林业实验中心伏波试验场营造了马尾松和杉木纯林.为了提高针叶纯林的生产力和维护生态平衡,2007-2008年间,运用近自然森林培育技术,分别在间伐后的马尾松和杉木纯林中套种等量混合的当地优质乡土树种红椎(Castanopsis hystrix)和香梓楠(Michelia gioii苗木,套种密度均为405株/hm2(以下简称“马尾松近自然林”、“杉木近自然林”).选择邻近地块相同林龄、相似立地条件的未经改造的马尾松、杉木人工纯林作为对照(以下简称“未改造纯林”),研究了马尾松和杉木人工针叶纯林近自然改造早期对群落特征和土壤性质的影响,以期为马尾松和杉木人工林的可持续经营提供科学依据.研究结果表明:(1)近自然林中马尾松和杉木的密度、胸高断面积均显著低于各自未改造纯林(P<0.05),但其平均胸径均高于各自未改造纯林,其中马尾松达显著差异(P<0.05).(2)近自然林成年树(DBH≥10 cm)的林木株数少于未改造纯林,树种仍以马尾松和杉木占据绝对优势地位,而近自然林小树(5 cm≤DBH<10 cm)和幼树(1 cm≤DBH<5 cm)的物种数、株数均多于未改造纯林,套种的红椎和香梓楠已经成为近自然林中重要值最大的幼树物种,红椎和香梓楠在马尾松近自然林中的生长状况优于杉木近自然林.(3)马尾松近自然林灌木层和草本层的物种丰富度指数、Shannon-Wiener指数、Simpson指数和Pielou指数与其未改造纯林均无显著差异;杉木近自然林灌木层的丰富度指数和草本层的Pielou指数显著高于其未改造纯林(P<0.05),其他指数则没有显著差异.(4)马尾松和杉木近自然林的土壤容重、总孔隙度、全磷、全氮、全钾和速效钾与各自未改造纯林没有显著差异,但马尾松近自然林的土壤有机碳含量和pH值显著低于其未改造纯林(P<0.05),杉木近自然林的速效磷含量显著低于其未改造纯林(P<0.05).  相似文献   

19.
生物多样性和生态系统功能的关系直接或间接地影响着生产力, 是生态学研究的关键问题。本研究旨在定量探讨亚热带自然林演替后期森林生态系统树木多样性与生物量或生产力的关系。本研究基于中国南亚热带长期永久性样地的群落调查数据以及地形和土壤养分数据, 分析了南亚热带常绿阔叶林树木多样性与生物量和生产力的关联及其影响因素。相关性分析结果表明, 物种多样性与生物量呈显著负相关, 与生产力呈显著正相关; 结构多样性与生物量呈显著正相关, 与生产力呈显著负相关。此外, 不同环境因子对多样性、生物量和生产力的影响具有显著差异, 其中土壤含水量对生产力有显著影响, 物种多样性指标与部分地形和土壤因子均有相关性, 而群落结构多样性指标与土壤因子的相关性更强。方差分解结果表明, 结构多样性对生物量和生产力的单独效应的解释率最大, 分别为35.39%和5.21%; 其次是结构多样性和物种多样性的共同效应, 对生物量和生产力的解释率分别为13.66%和3.53%; 地形和土壤因子的解释率较小。同时, 结构方程结果也表明, 结构多样性对生物量有较强的直接正影响; 生物量对生产力有强烈的直接负影响, 结构多样性通过增加生物量明显地减少了生产力; 土壤和地形因子主要是通过物种和结构多样性间接影响生物量和生产力。综上, 本研究认为在南亚热带森林演替顶极群落中, 群落结构复杂性和物种多样性的提高对促进群落生产力和生物量具有重要作用。  相似文献   

20.
以贵州省宽阔水国家级自然保护区亮叶水青冈(Fagus lucida)群落为研究对象,基于野外实地调查,应用数量生态学的方法,对保护区内亮叶水青冈群落特征及物种多样性进行了研究,对保护区内植物群落动态变化监测以及对亮叶水青冈群落的保护和管理都具有一定的理论指导意义。结果表明:设置样地共11700m2,调查样地内维管束植物62科,111属,165种,其中蕨类植物4科,6属,6种,种子植物58科,105属,159种。其中以单种科和寡种科(2-5种)占优势,两者的比例之和超过总科数的85%,蔷薇科共有植物6属15种,为所有科中最多,其他属数较多的科有樟科和壳斗科。属的结构中以单种属占据绝对优势,达到70.27%,山矾属和悬钩子属种数最多,各有6种。亮叶水青冈在群落中虽占优势,但龄级结构出现双峰值的异常趋势,种群呈衰退趋势。从总体趋势上来看,群落物种多样性指数均为乔木层 > 灌木层 > 草本层;物种丰富度指数灌木层 > 乔木层 > 草本层;均匀度指数乔木层 > 草本层 > 灌木层。亮叶水青冈幼苗和幼树除在局部区域较集中分布外,其余大部分区域数量均少,且受林下金佛山方竹(Chimonobambusa utilis)干扰较强,大径级植株比重大,年龄结构总体呈衰退型,在未来种群稳定性维持较为困难。应加强对保护区亮叶水青冈的保护,建议合理抚育管理亮叶水青冈幼苗,在森林的经营和管理上,对亮叶水青冈林可在其生长到一定阶段时适度进行人为干扰,会更有利于亮叶水青冈林的更新和生长发育。  相似文献   

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