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1.
以云南沾益大毛寺原生天坑为例,获取坑内植物群落林木个体相对位置信息,进行角尺度、混交度、林层指数等林木空间结构参数与坑底植物群落空间格局分析,并运用点格局分析方法进行单个种群的空间分布特征以及不同种群间的空间关联性分析.结果表明: 大毛寺原生天坑坑底植物群落在空间分布上呈现随机分布,林木物种呈中度混交,林木垂直分层虽较简单,但结构稳定,具有发育成熟的顶极森林群落的空间分布特征;坑底植物群落的种群主要呈聚集分布,种群间呈负关联,且处于同一垂直层次上种群间空间负相关性更强,垂直层次相差越大,空间竞争性越小,而随着空间范围的增大,空间负关联越弱;坑内生态系统具有较高的稳定性,是难得的物种自然栖息地和生态避难所,独特生境中形成的稳定植物群落结构在喀斯特地区生态恢复研究中具有重要的借鉴意义和导向作用.  相似文献   

2.
西藏冷杉原始林群落物种多样性初步研究   总被引:12,自引:0,他引:12  
物种多样性是反映植物群落内各物种在组成、结构和动态方面存在差异程度的指标。随着植物群落结构、功能和所处环境因子的变化 ,群落内物种多样性也随之发生变化。根据物种多样性指标 (多样性、丰富度、均匀度指数等 )的变化特征 ,能够深入揭示植物群落的环境变化梯度和结构变化、功能演化的趋势。通常应用α多样性和 β多样性来分别测度群落内和群落间物种多样性的变化特点[2 ,3 ] ,并取得了一批成果[4 ,7,10 ,13 ] ,同时在种群生态位、种间联结、种间竞争等理论研究方面也得到广泛应用[1,8,11] 。西藏自治区是青藏高原的主体 ,藏东南(林芝…  相似文献   

3.
张琳  陆兆华  唐思易  张萌  张润廷  黄玉凯  尚志 《生态学报》2021,41(14):5764-5774
研究植被恢复过程中植物群落组成、结构及稳定性的变化,可进一步了解到植物群落的演替过程及规律。采用空间代时间的方法对内蒙古锡林郭勒盟北电胜利露天煤矿4个排土场边坡人工恢复植被进行群落调查,在此基础上采用多样性指数与优化后的M.Godron稳定性指数对植物物种组成、物种多样性及其群落稳定性进行分析,探究不同恢复年限排土场边坡植被在恢复过程中群落特征及稳定性变化特征。结果表明:(1)排土场边坡植物物种组成共有16科44属56种,植物群落组成较简单,其中禾本科种类最多,生长型以草本植物为主。(2)随着恢复年限的增加,植物生活型由一、二年生转变为多年生,坡面优势种由人工种植植物转变为本土植物。(3)整体看,随着恢复年限增加,物种多样性呈下降趋势,群落稳定性整体呈上升趋势。(4)由于不同坡向土壤微环境差异,北坡恢复效果及稳定性好于南坡。本研究在一定程度上可为露天煤矿排土场边坡人工修复过程中植物物种及合理配置模式的选择提供科学依据。  相似文献   

4.
植物群落与异质性   总被引:8,自引:0,他引:8  
异质性,对应于植物群落所要求的同质性模型,广泛地存在于植物群落中,但是对其生态学意义的解释却极为模糊。就植物群落中生物的化感作用和非生物的地形因子等两个方面的原因,揭示了植物群落异质性的潜在机制,并阐述了异质性对植物群落的物种组成、种群的分布格局、生态位和群落的动态等方面具有强烈的影响。其结果表明,植物群落组成、结构和动态,其实质就是异质性的趋同化和再异质化的过程。  相似文献   

5.
本研究从三方面考察了斧头湖荇菜群落的结构,并对其进行了周年观察,荇菜群落内共有13种植物,可归为5个生活型11个生长型,其物种组成较贫乏,浮叶水植物群落的物种结构较挺水植物群落简单,荇菜群落呈带状和斑块状分布,荇菜种群的群聚规模从0.08-0.64m^2不等。群落的垂直结构分两层:浮叶植物层和沉水植物层,无发达的地下根茎系统和水上层。群落内荇菜种群在5月下旬达到最大现存量和生殖高峰,之后在一个低的  相似文献   

6.
森林砍伐对苦槠种群遗传结构的影响   总被引:2,自引:0,他引:2  
简耘  石磊  李丹  张纯淳  石苗苗  王嵘  陈小勇 《生态学报》2008,28(12):6228-6234
人类活动严重干扰着自然生态系统,其中砍伐是对森林生态系统最常见的干扰之一,它导致森林退化,植物种群变小,甚至灭绝,遗传多样性也随之下降。当被破坏的森林未被转换性利用时,则会逐渐恢复,但由于瓶颈效应,恢复起来的生态系统中植物种群的遗传结构可能会改变。恢复种群遗传组成的改变一方面与干扰的强度、频度和持续时间有关,另一方面,也受植物生活史特点的深刻影响。然而,我国对于砍伐后恢复起来的森林生态系统中生物多样性的改变,尤其是遗传多样性的改变的研究并不多见。研究在浙江省宁波市天童国家森林公园及周边地区选择了5个苦槠种群,采用SSR微卫星标记来分析砍伐对苦槠种群遗传结构的影响。5对多态SSR引物共得到了29个等位基因。种群内维持了较高的遗传多样性,种群间遗传分化程度较低,基因流达8.68。恢复林和成熟林种群的遗传多样性相差不大,以阿育王寺地区恢复种群的最高;表明砍伐对于苦槠种群遗传多样性的影响不大,这与苦槠较强的萌条能力有关。尽管如此,在恢复种群中观察到近期的种群瓶颈,显示出砍伐对种群遗传组成的影响;而在一个成熟林中也观察到种群瓶颈,这是因片断化导致种群变小之故。植被保存最好的天童国家森林公园内苦槠种群的遗传多样性却较低,这可能与成熟林中苦槠优势度较低有关。  相似文献   

7.
王恒方  吕光辉  周耀治  曹靖 《生态学报》2017,37(23):7928-7937
功能多样性和功能冗余是物种多样性的两个组成部分,也是影响群落稳定性的两个重要因素。基于不同水盐梯度下植物功能多样性、功能冗余、物种多样性和群落稳定性及其相关关系的计算结果,分析功能多样性和功能冗余对群落稳定性的影响,结果表明:(1)功能多样性、物种多样性和群落稳定性均表现为高水高盐和中水中盐群落显著高于低水低盐群落(P0.05);(2)高水高盐群落,功能多样性与物种多样性的相关系数小于功能冗余与物种多样性的相关系数,且功能多样性与稳定性的相关系数也小于功能冗余与稳定性的相关系数,而中水中盐和低水低盐群落的相关系数则呈现相反的规律;(3)中水中盐和低水低盐群落的功能多样性的标准化偏回归系数均大于功能冗余的标准化偏回归系数;(4)典范对应分析中,土壤含水量可以解释总特征根的22.7%,而土壤含盐量仅可以解释总特征根的1.3%;(5)高水高盐群落的稳定比最接近20/80,稳定性最高;低水低盐群落远离20/80,稳定性最低。改进后的Godron稳定性测定方法与物种种群密度变异系数方法得出的结果相同。综上可知,功能多样性和功能冗余两者中与物种多样性关系更为密切者对群落稳定性的影响也越大,且两者均可提高群落稳定性,也就证明冗余假说在温带干旱荒漠区域的隐域性植物群落中是成立的;群落稳定性、功能多样性、功能冗余及物种多样性主要是受土壤含水量的影响,土壤含盐量对其影响较小。  相似文献   

8.
AM真菌在草原生态系统中的功能   总被引:3,自引:0,他引:3  
金樑  孙莉  王强  董梅  王晓娟  王茜  张亮 《生态学报》2016,36(3):873-882
AM真菌是土壤生态系统中重要的微生物类群,能与陆地生态系统中80%以上的高等植物建立共生体系。目前,AM真菌在维持草原生态系统稳定性中的功能已经成为生态学研究的热点问题之一。基于此,从植物个体、种群、群落和生态系统等不同层次探究AM真菌在维持植物群落多样性和草原生态系统稳定性中的功能。分析发现在个体水平上,AM真菌对宿主植物具有促生效应、抑制效应或中性效应。在种群水平上,分析AM真菌对不同宿主植物吸收土壤矿质营养的分配和调控策略,围绕构成草原植被的两大组成成分:牧草和有毒植物,论述AM真菌对植物种群增长和衰败的调控机制,并从草原植物群落的物种多样性和稳定性角度,探讨AM真菌与植物群落之间的相关性。在生态系统水平上,围绕AM真菌对草原生态系统的演替和退化草原的修复等展开论述,以期为利用AM真菌开展草原生态系统保护和恢复治理提供理论依据,并对草原菌根生态学领域未来的研究进行展望。  相似文献   

9.
人为干扰下的亚高山草甸功能多样性和功能冗余 人为干扰程度的加剧会引起植物群落物种多样性和功能多样性的改变,并降低生态系统的稳定性。较高水平的功能冗余对于物种损失引起的生态系统功能和稳定性的改变起到了重要的缓冲作用。然而,关于亚高山草甸植物群落功能冗余对干扰的响应的研究相对较少。本研究的目的是,确定人为干扰下不同退化程度的亚高山草甸,其植物群落功能多样性和功能冗余对干扰的响应特征,及不同物种对功能冗余的贡献程度及其在干扰梯度上的变化规律。研究区位于青藏高原东南缘玉龙雪山上的亚高山草甸。本研究识别出4类干扰强度(无干扰、弱干扰、中度干扰和重度干扰),测定了干扰梯度上的植物物种组成、土壤性质和5个关键的植物功能性状等指标,进一步计算了Simpson多样性指数、功能多样性指数(RaoQ)、功能冗余度、群落的植物功能性状加权平均值(CWM)以及物种水平的功能冗余等指数。研究结果表明,功能多样性和功能冗余在干扰梯度上呈现单峰变化规律,即二者分别在中度干扰、弱干扰下达到最大值。物种多样性在干扰梯度上整体呈下降趋势。随着干扰程度的增加,采取保守生长策略并具有相关性状特征(如较低比叶面积和较高的干物质含量)的物种的丰富度降低,采取资源获取策略并具有相关性状(如低矮植株、较高的比叶面积和较低的干物质含量)的物种增加。不同物种的功能冗余程度存在差异。值得注意的是,一些物种在群落中扮演着独特的功能角色,如无干扰梯度下的网脉橐吾(Ligularia dictyoneura)以及中度和重度干扰梯度下的滇西委陵菜(Potentilla delavayi)。  相似文献   

10.
冗余概念的界定与冗余产生的生态学机制   总被引:11,自引:1,他引:10  
冗余是指这样的生命实体,由于其存在,导致生物个体、种群、群落乃至生态系统水平上的对人类有益的功能输出降低,通过管理措施或育种手段剔除这部分‘冗余’实体,个体、种群、群落乃至生态系统水平上对人类有益的功能就会得到加强,我们把这样的生命实体叫做冗余。或者简单地说,冗余是指对目标产量输出构成影响的各种水平的生物有机体过多或过于庞大的部分。冗余的产生过程是整个生命有机体的总体功能扩展过程,冗余的产生和存在,有助于增强有机体的稳定性,提高其适应自然环境波动的能力。根据其影响的水平,冗余可发生在个体、种群及群落等水平上。植物在个体及群体水平上的补偿及超补偿可以通过剔除各生命系统中不同水平上的冗余实现,即剔除冗余有助于目标物种或目标器官产量的提高,并且这种提高是以对波动环境适应能力和抗扰动能力的降低为代价的。  相似文献   

11.
生态系统管理的基本问题   总被引:49,自引:3,他引:46  
赵士洞  汪业勖 《生态学杂志》1997,16(4):35-38,46
生态系统管理的基本问题赵士洞汪业勖(中国科学院国家计划委员会自然资源综合考察委员会,北京100101)SummaryonEcosystemManagement.ZhaoSidong,WangYexu(CommisionforIntegratedSur...  相似文献   

12.
We used measurements of CO2 exchange by six Canadian boreal forest stands to determine how sites of contrasting age respond to interannual temperature and precipitation variation. The stands ranged in age (time since last burn) from 4 to 155 years. The study included years that were anomalously cool and moist, warm and dry, cool and dry, and warm and moist. Warmer than average springs accelerated the onset of older stand (> 20 years) photosynthesis by as much as 37 days and younger stand (< 20 years) photosynthesis by as much as 25 days. The warm–dry year resulted in a marked reduction of mid‐summer CO2 uptake by the younger, but not older, stands. The mid‐summer decline in young stand photosynthesis reflected the combination of warmth and drought; similar declines were not observed during the cool–dry or warm–moist years. The annual carbon gain by the oldest stands was greatest during the warm–dry year as a result of the expanded growing season. The annual carbon gain by the youngest stands was consistent from year to year, largely as a result of offsets between increased spring photosynthesis and reduced mid‐summer photosynthesis during the warm–dry year. Night‐time CO2 efflux increased by 2–29% during the warm–moist year relative to the warm–dry year. This increase was not systematically related to age. We conclude that the major source of interannual CO2 exchange variation at the landscape scale is the ability of older, evergreen canopies to respond to warm springs by advancing the onset of photosynthesis. Drought‐related reductions in photosynthesis, moisture‐driven respiratory losses, and the effects of spring warmth on young‐stand photosynthesis are of secondary importance. The advantage conferred on older, evergreen stands during warmer years carries implications for the possible effects of climate change on boreal forest succession. Warmer temperatures may increase the competitive advantage of late successional species relative to early successional species, and also the incidence of fire, thereby accelerating plant succession and shortening the fire‐return interval.  相似文献   

13.
Copper (Cu)-polluted and unpolluted soils were used to study the effect of initial pollution on soil biological resistance and resilience by measuring the responses to perturbation using different parameters. Microbial biomass carbon, substrate-induced respiration and copy numbers of 16S rRNA gene were grouped as general parameters, while potential ammonia oxidation rate and copy numbers of amo A gene were grouped as specific functions. In addition, to illustrate how initial pollution affects soil biological resistance and resilience following secondary perturbation, the microbial community structure, together with free Cu2+ activities ([Cu2+]) in soil pore water and soil pH were also measured after secondary perturbation. Results showed that general parameters were more stable than specific ones. High [Cu2+] and low pH in soil pore water induced by Cu addition may lead to apparently low resistance and resilience, whereas the formation of a tolerant community after Cu pollution, secondary perturbation and Cu aging may contribute to resistance and resilience. Analysis of the phospholipid fatty acids profile showed that microbial community structure shifted along with the [Cu2+] gradient. The microbial community structure of the control soil was both resistant and resilient to 400 mg kg−1 Cu perturbation, whereas other treatments were neither resistant nor resilient.  相似文献   

14.
沱江流域两种人工针叶林群落结构比较   总被引:1,自引:0,他引:1  
采用样方调查法比较了沱江流域两种人工针叶林群落的结构.结果表明,湿地松林中湿地松幼苗幼树很少;马尾松林中有较多的马尾松幼苗幼树.马尾松种群多度比湿地松种群大38%,而湿地松种群的平均高度、平均冠幅比马尾松种群分别大32.7%和22.2%.从高度结构及径级结构来看,马尾松种群在各个级别上都有分布;而在湿地松种群中,没有Ⅰ...  相似文献   

15.
Group or population level self-organised systems comprise many individuals displaying group-level emergent properties. Current theory indicates that individual-level behaviours have an effect on the final group-level behaviour; that is, self-organised systems are sensitive to small changes in individual behaviour. Here we examine a self-organised behaviour in relation to environmentally-driven individual-level changes in behaviour, using both natural systems and computer simulations. We demonstrate that aggregations of intertidal snails slightly decrease in size when, owing to hotter and more desiccating conditions, individuals forage for shorter periods--a seemingly non-adaptive behaviour for the snails since aggregation reduces desiccation stress. This decrease, however, only occurs in simple experimental systems (and simulations of these systems). When studied in their natural and more complex environment, and simulations of such an environment, using the same reduced foraging time, no difference in aggregation behaviour was found between hot and cool days. These results give an indication of how robust self-organised systems are to changes in individual-level behaviour. The complexity of the natural environment and the interactions of individuals with this environment, therefore, can result in self-organised systems being more resilient to individual-level changes than previously assumed.  相似文献   

16.
Litter decomposition rates and the population densities of soil microarthropods were measured in three Pinus pinaster stands thirty-one, twenty-three and eighteen years old, and on an area of native vegetation on sandy soil at Gnangara, W.A. Litter decomposition was faster in the soil than within the litter layer and was slowest at the litter surface. Decomposition was rapid in cool wet seasons and slow in hot, dry summers. Microarthropod population densities were similar on all sites (77–100 × 103/m2) but species diversity was greatest under native vegetation and least under the youngest pine stand. The impoverished soil micro-fauna of the pine stands is unable to decompose pine or sclerophyll litter as fast as the full complement of soil microfauna in native vegetation.  相似文献   

17.
Despite recent findings on the ecological relevance of within population diet variation far less attention has been devoted to the role diet variation for ecological services. Seed dispersal is a key ecological service, affecting plant fitness and regeneration based on foraging by fruit‐eating vertebrates. Here we used a network approach, widely used to understand how seed‐dispersal is organized at the species level, to gain insights into the patterns that emerge at the individual‐level. We studied the individual fruit consumption behavior of a South American didelphid Didelphis albiventris, during the cool–dry and warm–wet seasons. In species–species networks the heterogeneity in specialization levels generates patterns such as nestedness and asymmetry. Because generalist populations may be comprised of specialized individuals, we hypo thesized that network structural properties, such as nestedness, should also emerge at the individual level. We detected variation in fruit consumption that was not related to resource availability, ontogenetic or sexual factors or sampling biases. Such variation resulted in the structural patterns often found in species–species seed‐dispersal networks: low connectance, a high degree of nestedness and the absence of modules. Moreover structure varied between the warm–wet and cool–dry seasons, presumably as a consequence of seasonal fluctuation in fruit availability. Our findings suggest individuals may differ in selectivity causing asymmetries in seed dispersal efficiency within the population. In this sense the realized dispersal would differ from the expected dispersal estimated from their average dispersal potential. Additionally the results suggest possible frequency‐dependent effects on seed dispersal that might affect individual plant performance and plant community composition.  相似文献   

18.
Terrestrial arthropod communities usually consist of very large species numbers. Data from experiments or long time‐series would be required to ascertain the functional significance of individual species. Both are largely unavailable for species‐rich natural communities. Recognising structural redundancies in species composition allows for an alternative approach to address how strong functional redundancy might be in natural assemblages, if structural and functional redundancies are related to each other. Determining structural redundancies is a regular topic in aquatic ecology, but has rarely been applied to terrestrial communities. We explored the extent of structural redundancy in species‐rich terrestrial insect assemblages and whether structural redundancies are contingent to species abundances or functional group affiliations. We used the BVSTEP algorithm to determine structural redundancies in a large data set of moth species (32 181 individuals; 448 species) that had been sampled with light‐traps in three different floodplain forests in eastern Austria. We partitioned the moth species into 12 functional types based on larval host‐plant affiliations to test if moth species included in reduced subsets represent functional groups in the same proportions as they occur in the entire fauna. We observed far more massive structural redundancies in moth assemblages than previously found in aquatic communities. Subsets containing only 8–15 species (1.8–3.3% of all recorded species) were still highly representative for the overall data. Subsets selected by the BVSTEP procedure performed better than equally small subsets that were defined solely by species abundances or by functional group affiliations. Effective ‘surrogate’ subsets contained only 6–9 of the 12 functional moth types. High abundance only loosely corresponded with the frequency at which a moth species was included in the subsets. Thus, certain uncommon species contribute importantly to species composition patterns. Our results show unexpectedly extensive structural redundancies in complex floodplain forest moth communities, which may also indicate strong functional redundancies.  相似文献   

19.
Populations of the introduced Heracleum mantegazzianum consist of dense central stands, which gradually give way to open stands towards the margins. To analyse whether open stands are due to unsuitable conditions or represent the invading front for further spread, we studied life-cycle, population dynamics, stand structure and soil conditions of open and dense stands over two transition periods. Populations decreased during the first interval but increased after the extremely dry and warm summer of 2003 during the second interval. Open stands had shorter generation times, lower height, smaller proportions of small individuals and were less in equilibrium with the environment than dense stands. In open stands, growth to higher stages was most important, while in dense stands delayed development (self-loops) had a strong effect on population growth; stasis and fecundity contributed most to the difference in λ between stand types. By petiole extension H. mantegazzianum may raise its leaves just above the resident vegetation. Therefore, younger stages develop faster in open stands, whereas strong competition by conspecific adults leads to longer generation times and a higher proportion of small individuals in dense stands. Disturbance due to extreme climatic conditions in summer 2003 equalised population dynamics of both stand types. Life-cycle variation between stand types makes it difficult to infer simple management rules. However, our data suggest that small and/or open stands of H. mantegazzianum may eventually serve as initials for further spread after land-use changes, whereas dense stands are stable and may represent sources of propagules.  相似文献   

20.
对古尔班通古特沙漠南缘6个不同林龄人工梭梭种群的结构特征、天然更新及影响因子进行研究.结果表明: 7年生人工梭梭林能天然更新,17年生时幼苗(高度H<30 cm)、幼树(30≤H<50 cm)和小树(H≥50 cm)的密度均达到“优”级,小树的平均高度和基径为1.10 m和1.91 cm.20年生人工梭梭林内母树长势最好,35%的个体树高在2.50~3.00 m,23.1%个体的基径达8.00~10.00 cm; 33年生人工梭梭林内母树高和径生长明显衰退,但自然落种更新能力依然较强; 梭梭自然落种更新密度与0~100 cm土层土壤有效氮含量的关联度最大(0.87),其次是土壤速效磷(0.84)及土壤水分含量(0.79),pH 8.1~8.6的土壤未限制更新层的营养生长.在主林层,与整个更新层个体密度关联性最高的是人工梭梭林母树生物量(0.77),而与更新层小树密度关联性最高的是种植密度(0.71)和母树年龄(0.70).  相似文献   

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