首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 9 毫秒
1.
This study tested an hypothesis concerning patterns in species abundance in ecological communities. Why do the majority of species occur in low abundance, with just a few making up the bulk of the biomass? We propose that many of the minor species are analogues of the dominants in terms of the ecosystem functions they perform, but differ in terms of their capabilities to respond to environmental stresses and disturbance. They thereby confer resilience on the community with respect to ecosystem function. Under changing conditions, ecosystem function is maintained when dominants decline or are lost because functionally equivalent minor species are able to substitute for them. We have tested this hypothesis with respect to ecosystem functions relating to global change. In particular, we identified five plant functional attributes—height, biomass, specific leaf area, longevity, and leaf litter quality—that determine carbon and water fluxes. We assigned values for these functional attributes to each of the graminoid species in a lightly grazed site and in a heavily grazed site in an Australian rangeland. Our resilience proposition was cast in the form of three specific hypotheses in relation to expected similarities and dissimilarities between dominant and minor species, within and between sites. Functional similarity—or ecological distance—was determined as the euclidean distance between species in functional attribute space. The analyses provide evidence in support of the resilience hypothesis. Specifically, within the lightly grazed community, dominant species were functionally more dissimilar to one another, and functionally similar species more widely separated in abundance rank, than would be expected on the basis of average ecological distances in the community. Between communities, depending on the test used, two of three, or three of four minor species in the lightly grazed community that were predicted to increase in the heavily grazed community did in fact do so. Although there has been emphasis on the importance of functional diversity in supporting the flow of ecosystem goods and services, the evidence from this study indicates that functional similarity (between dominant and minor species, and among minor species) may be equally important in ensuring persistence (resilience) of ecosystem function under changing environmental conditions.  相似文献   

2.
随着航空业的发展,野生动物与飞机之间的冲突愈发密集,机场鸟类群落多样性研究引起了大量关注。研究鸟类群落对生境类型的使用状况,可以掌握生境类型与鸟击风险的潜在关系,为机场环境改造提供理论依据。本研究于2019年7月至2021年11月,采用样点法对扬州泰州机场及周边8 km范围内的农田、湿地、林地和城镇4种生境中30个样点的鸟类群落进行调查。利用鸟类群落多样性指数,包括丰富度、多度、香农威纳多样性指数、辛普森多样性指数以及均匀度指数来表征群落的物种多样性,以及功能和谱系多样性,阐明机场周边4种生境的鸟类群落多样性差异。同时,基于多度加权的平均成对功能距离(MFD)和平均成对谱系距离(MPD)来表征群落的功能和谱系结构,探究群落构建机制,量化各多样性指标间的相关性。研究共记录扬州泰州国际机场鸟类88种,分别隶属于14目36科,目、科中数量最多的为雀形目(Passeriformes)和鹬科(Scolopacidae)。谱系和功能多样性在生境间差异显著,功能分散度在农田最高,城镇最低;谱系多样性指数在城镇最高,湿地最低。标准化效应值分析表明,随机生态过程影响了湿地鸟类群落功能和谱系的构建过程,农...  相似文献   

3.
拉鲁湿地主要植物群落结构及物种多样性   总被引:2,自引:0,他引:2  
李春  周刊社  李晖 《西北植物学报》2008,28(12):2514-2520
2002年6~9月对拉鲁湿地植物种类、群落结构、生物量以及物种多样性进行了调查研究.结果表明:(1)拉鲁湿地共有植物30科52属85种,主要有芦苇[Phragmites australis(Cav.)Trin.ex Steud.](A)、尼伯尔酸模(RumexnepalensisSpreng)(B)、水葱(Scirpus validusVahl)(C)、穗状狐尾藻(MyriophyllumspicatumL.)(D)、灯芯草(Juncus effususL.)(E)、针叶苔草(CarexonoeiFranch.et Sav.)和黑褐苔草(CarexatrofuscaSchkuhr)(F)、藏北嵩草(KobresialittledaleiC.B.Clarke)(G)、藏蓟[Cirsiumlanatum(Roxb.ex Willd.)Spreng.](H)等8个主要植物群落.(2)在8个主要植物群落中,嵩草群落所含物种数最多,为44种,穗状狐尾藻群落最少,仅8种;芦苇群落生物量最高,为124.5~1 027.0 g/m2,藏蓟群落生物量最低,为124.5~220.5 g/m2;优势种芦苇的生物量最高,为183.5~660.0 g/m2,藏蓟生物量最低,为43.1~76.3 g/m2.(3)各群落的垂直结构特点是:芦苇群落、水葱群落、穗状狐尾藻群落具有挺水层、浮叶层和沉水层,其他群落只具有可分为高、低两层的草本层.(4)在各群落的相似性方面,嵩草群落与藏蓟群落、水葱群落与芦苇群落和尼伯尔酸模群落的相似性要明显高于其他群落,其Jaccard系数分别为0.549 0、0.538 5、0.500 0;芦苇群落、尼伯尔酸模群落、水葱群落、穗状狐尾藻群落与藏蓟群落以及芦苇群落、穗状狐尾藻群落与嵩草群落在建群种上没有相似之处,Jaccard系数为0.  相似文献   

4.
通过野外实地调查对小勾儿茶变种毛柄小勾儿茶(Berchemiella wilsoniivar. pubipetiolata)伴生群落4个分布点(浙江省临安市湍口和马啸、安徽省霍山县马家河和舒城县万佛山)的种类组成及物种多样性进行研究。结果表明:(1)种类丰富,但含多属或多种的大科、大属的优势地位不明显,极小科(仅含1属)、极小属(仅含1种)所占比例大;(2)属的北温带分布类型最多,科的世界分布类型比例大,仅次于泛热带分布类型;(3)4个分布群落乔木层、灌木层、草本层优势度均很低;灌木层Shannon-Wiener多样性指数较大,在4.13~4.49之间,乔木层和草本层较低。湍口、马家河、万佛山以灌木层Heip均匀度指数最大,马啸以乔木层均匀度指数最大;(4)马家河与万佛山之间的植物种类组成最相近,湍口与马啸也较相近;乔木层种类组成差异最大,灌木层最小。  相似文献   

5.
植物群落物种多样性研究综述   总被引:108,自引:4,他引:108  
物种多样性是生物多样性在物种水平上的表现形式 ,包括两方面的含义 ,一是指一定区域内物种的总和 ,主要从分类学、系统学和生物地理学角度对一个区域内物种的状况进行研究 ,也称区域物种多样性 ;二是指生态学方面物种分布的均匀程度 ,常常是从群落组织水平上进行研究 ,也称为生态多样性或群落多样性[1] 。本文所涉及物种多样性即为群落组织水平上的物种多样性。植物群落物种多样性的研究是其它多样性 (遗传多样性、生态系统多样性等 )的基础 ,有大量的研究成果相继报道 ,也有一些综述对植物群落物种多样性某一领域的研究进行总结。Magu…  相似文献   

6.
内蒙古高原4类地带性草原群落,贝加尔针茅(Stipa baicalensis Roshew.)群落、大针茅(S.grandis P.Smirn.)群落、克氏针茅(S.krylovii Roshev.)群落和小针茅(S.klemenzii Roshev.)群落初级生产力连续12年的定位研究结果表明,在气修波动下群落生产力及其稳定性与群落多样性特征的变化是一致的,从贝加尔针茅群落到小针茅群落。植物多样性显下降,群东中起重要作用的植物功能群的数量逐渐减少,群落初级生产力及其稳定性也逐渐降低。生活型功能群组成中,多年生丛生禾草、多年生根茎禾草与苔草和多年生杂类草功能群多样性与群落初级生产力稳定性极显地呈正相关。生态类群组成中,旱生植物和中旱生植物功能群多样性也与群落初级生产力稳定性极显地呈正相关,生态位互补效应(niche complementary effect)可能是高植物多样性群落具有高生产力的机制,而植物多样性对群落初级生产力稳定性的影响可能是通过不同功能群间的补偿作用来实现的。  相似文献   

7.
Abstract Empirical estimates of the function and resilience of communities under different management regimes can provide valuable information for sustainable natural resource management, but such estimates are scarce to date. We quantified the functional richness and relative resilience of bird communities inhabiting five regions in southeastern Australia that represented different management regimes. First, we show that functional richness and relative resilience were reduced at species-poor sites in all regions. Second, we show that bird communities in agricultural regions had fewer body mass groups and fewer functional groups than expected by chance. This suggests that both the function and the resilience of bird communities in agricultural regions were reduced. The likely mechanisms for the observed loss of function and relative resilience are: (1) the simplification of landscape texture resulting in selective extinction of certain body mass groups; and (2) the selective extinction of certain functional groups that are particularly sensitive to intensive land use. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

8.
稀有植物十齿花群落物种多样性研究   总被引:6,自引:0,他引:6  
林长松  左经会  廖雯 《植物研究》2008,28(3):353-358
运用样方法对贵州省玉舍国家级森林公园稀有保护植物十齿花(Dipentodon sinicus)群落的物种多样性进行了研究,结果表明:玉舍国家级森林公园十齿花群落以蔷薇科、杜鹃花科、壳斗科、桦木科、山茶科、樟科、忍冬科、山茱萸科等为优势科;10个样地中有8个样地以十齿花种群占绝对优势,其平均重要值高达135.69,远远高于其它种群;十齿花群落乔木层物种丰富度为2.847、Simpson指数为0.601、Shannon-Wiener指数为1.523、种间相遇机率为0.601、均匀度指数为0.569,总体上均小于灌木层(分别为:5.580、0.830、2.377、0.829、0.672),表现为较明显的亚热带常绿落叶阔叶混交林的物种多样性特征。10个样地中,Q1的物种多样性程度最高,Q3次之,Q5和Q6最小,多样性程度最低,10个样地的物种多样性排序为Q1>Q3>Q9>Q7>Q2>Q4>Q10>Q8>Q5>Q6。  相似文献   

9.
为了解贵州百里杜鹃自然保护区不同演替阶段植物群落物种多样性特征,该研究采用“空间代替时间”的方法,对该保护区内5个演替阶段的群落进行调查,并分析其物种组成、重要值、α及β多样性特征。结果表明:(1)研究区共调查到维管束植物56科103属140种,优势科有蔷薇科、杜鹃花科和百合科。(2)杜鹃花科植物在整个演替过程中占据综合优势地位,在各演替阶段灌木层重要值均排前三位。(3)沿进展演替方向,群落的Margalef丰富度指数(dMa)、Shannon-Wiener多样性指数(H′e)、Simpson指数(D)及Pielou均匀度指数(Je)均呈现先上升后下降再上升的趋势,最后群落结构趋于复杂,稳定性上升。(4)随着演替的正向进行,群落间丢失和增加的物种数逐渐变多,物种替代率逐渐升高;物种相似性系数在整个演替过程中不相邻阶段间均表现为极不相似。研究认为,保护区应制定合理的保护措施,避免人为活动的破坏,提升群落稳定性,保护群落结构及物种多样性,为发挥生态功能及可持续发展提供科学支撑。  相似文献   

10.
The distribution and species diversity of plant communities along a 600 km transect through the northeastern Tibetan Plateau (32°42′–35°07′ N, 101°02′–97°38′ E) with altitudes from 3255 to 4460 m are described. The transect started from the Youyi Bridge of Banma through Dari, Maqin and Maduo to Zaling Lake. The data from 47 plots along the transect are summarized and analyzed. The mean annual temperature, the mean annual rainfall and the length of growing season decreases from 2.6 to −4.5 °C, from 767.2 to 240.1 mm, from 210 to 140 days, respectively, along the transect from the southeastern Banma to northwestern Zaling Lake. The number of vascular plant species recorded in 47 plots is 242 including 2 tree, 34 shrub, 206 herb species. Main vegetation types on the transect from southeast to northwest are: Sabina convallium forest, Picea likiangensis forest, Pyracantha fortuneana + Spiraea alpina shrub, Hippophae neurocarpu shrub, Sibiraea angustata + Polygonum viviparum shrub, Stellera chamaejasme herb meadow, Potentilla fruticosa + Salix obscura + Carex sp. Shrub, Kobresia capillifolia meadow, P. froticosa + Kobresia humilis shrub, Caragana jubata + S. obscura shrub, Kobresia tibetica meadow, Kobresia pygmaea meadow, K. pygmaea + Stipa purpurea steppe meadow, Stipa purpurea steppe. Plant richness and diversity index all showed a decreasing trend with increasing of elevation along transect from southeast to northwest. Detailed information on altitudinal ranges and distribution of the alpine vegetation, vascular flora and environments over the alpine zone at northeastern Tibetan Plateau provides baseline records relevant to future assessment of probable effects of global climate changes.  相似文献   

11.
为探究神木垒不同森林群落林下植物多样性的差异,本研究采用典型样地法,以夹金山神木垒的5种主要森林群落:云杉林、丽江云杉林、红杉林、针阔混交林、阔叶林为研究对象,对不同森林群落林下植物物种组成和物种多样性进行比较,并对林分因子和林下植物多样性进行冗余分析,确定影响林下植物多样性的主要林分因子,为当地森林经营管理提供理论依据。结果表明:(1)在研究区内共记录林下植物147种,隶属于61科,108属;云杉林群落林下植物的科属种组成最丰富。(2)各类型群落的H值、H"值、D值、JSW值均为:草本层>灌木层;灌木层多样性最高的群落为云杉林群落,草本层多样性最高的群落为丽江云杉林群落,针阔混交林群落、阔叶林群落林下植物多样性较差。(3)平均枝下高与林分密度是影响灌木层物种多样性的主要林分因子(P<0.01),平均枝下高与灌木层的D值、H值、H"值呈负相关关系,林分密度与灌木层4个多样性指数均呈正相关关系;平均枝下高是影响草本层物种多样性的主要林分因子(P<0.01),平均枝下高与草本层H值、H"值、JSW值呈正相关关系。本研究认为,云杉林群落与丽江云杉林群落的林下植物多样性水平较高,平均枝下高与林分密度是影响神木垒不同森林群落林下植物多样性的主要林分因子。  相似文献   

12.
Phytocystatins constitute a multigene family that regulates the activity of endogenous and/or exogenous cysteine proteinases.Cereal crops like wheat are continuously threatened by a multitude of pathogens,therefore cystatins offer to play a pivotal role in deciding the plant response.In order to study the need of having diverse specificities and activities of various cystatins,we conducted comparative analysis of six wheat cystatins(WCs) with twelve rice,seven barley,one sorghum and ten corn cystatin sequences employing different bioinformatics tools.The obtained results identified highly conserved signature sequences in all the cystatins considered.Several other motifs were also identified,based on which the sequences could be categorized into groups in congruence with the phylogenetic clustering.Homology modeling of WCs revealed 3D structural topology so well shared by other cystatins.Protein-protein interaction of WCs with papain supported the notion that functional diversity is a consequence of existing differences in amino acid residues in highly conserved as well as relatively less conserved motifs.Thus there is a significant conservation at the sequential and structural levels;however,concomitant variations maintain the functional diversity in this protein family,which constantly modulates itself to reciprocate the diversity while counteracting the cysteine proteinases.  相似文献   

13.
浙江仙居俞坑森林群落物种多样性研究   总被引:4,自引:0,他引:4  
分别采用物种丰富度、物种多样性指数和群落均匀度指标对浙江省仙居县俞坑森林群落的物种多样性进行测定和分析。结果表明:本木植物的物种多样性以生境优越的常绿阔叶林为高,木本植物的物种丰富度、物种多样性指数明显大于草本植物。在群落垂直结构中,木本植物等2层的物种丰富度、物种多样性指数均显著大于第1层。物种丰富度以木本第3层最大,草本层最小;而物种多样性指数、群落均匀度则以木本第2层最大、草本层最小。木本植物各层次、草本层的物种多样性各项指标在群落各样地间均有一定的差异。  相似文献   

14.
划破草皮对高寒草甸植物多样性和生产力的影响   总被引:4,自引:0,他引:4  
本研究探讨了高寒草甸在不同划破强度下植被组成、多样性、功能群和生产力的变化.结果表明:垂穗披碱草等对土壤通透性和资源空间要求较高的物种,竞争力随划破强度的增加而上升,而对土壤通透性和资源空间要求相对较低的物种则相反;轻度划破干扰对提高物种丰富度具有一定的促进作用,但多样性指数则总体上表现为随划破强度的增加而呈下降的趋势;划破干扰对植被功能群的影响表现为以垂穗披碱草为代表的禾草类组分随干扰强度的增加而显著上升,莎草类和杂类草组分随干扰强度的增加而显著下降;划破干扰对草地初级生产力的提升具有显著的促进作用,且可显著增加植物总量中优质牧草的比重;划破干扰可独立作为高寒草甸类草地恢复与改良的有效措施,在定向培育垂穗披碱草型割草场的技术组合中具有核心和基础性的地位.  相似文献   

15.
Site‐to‐site variation in community composition, or beta diversity, is a major component of regional diversity. While many mechanisms, such as dispersal limitation and habitat heterogeneity, have been shown to affect beta diversity, interactions between habitat heterogeneity and environmental fluctuation have not been thoroughly investigated. This study uses leaf‐colonizing (epiphyllous) bryophyte communities as a model system to investigate the effects of microclimate fluctuation on beta diversity. I hypothesized that beta diversity would increase with increasing microclimate fluctuation, as niche breadth of species was reduced with increasing fluctuation. A total of 354 leaf‐colonizing bryophyte communities from 18 sites on the island of Moorea, French Polynesia were collected and identified. At each site, temperature and relative humidity were measured and converted to vapor pressure deficit (VPD). My analyses showed that beta diversity among communities on different host types tended to increase with the increasing daily range of VPD at a given site. It is possible that high fluctuation in microclimate conditions augments the differences in habitat quality among host types, resulting in greater dissimilarities among epiphyllous communities. However, host niche breadths of major epiphyllous species did not decrease with increasing VPD range. Overall, the results suggest that beta diversity may increase with environmental fluctuation, but it is not likely to be the results of reduced niche breadth as theoretically suspected.  相似文献   

16.
This study examine the notion of plant community complexity in a broad sense and develop a new measure based on the average length L(S) (L(S)=∑ qj=1p jl j ) of the communication-theoretical parsimonious code required to describe the community (S). Total complexity may be differentiated into organized and unorganized complexity. The author refers to Shannon-Wiener entropy H(S) (H(S)=-∑ qj=1 p j log 2 p j ) and Renyi entropy H 12 (S) (H α(S)=11-αlog 2∑ qj=1 p α j , where α =12) as “disorder-based complexity", L(S) as “total complexity" and the difference Δ(S)=L(S)-H(S) and Δ 12 (S)=L(S)-H 12 (S) as “structural complexity". The complexity and diversity of typical plant communities along the NECT (Northeast China Transect) were discussed. The results suggest that structural complexity is higher in the lightly grazed grassland than the heavily grazed grassland. Clearly, structural complexity and disorder-based diversity are not substitutes for one another and should be considered as autonomous, equally important properties. Δ 12(S) measures a community complexity distinct form the disorder-based complexity H 12 (S) .  相似文献   

17.
中国东北样带(NECT)植物群落复杂性与多样性研究   总被引:18,自引:0,他引:18  
在更广的意义上考虑群落复杂性的概念,将群落总复杂性分离为基于无序的复杂性和结构复杂性,并以群落的两个原始数据-群落组分(例如种群)数和各组分个体的比例分布为基础,用描述群落的最小剩余码的平均码长L(S)=q/∑/j=1pjlj(其中lj为物种S的相对多度的Huffman码字长度,q是物种数,pj满q/∑/j=1pj=1)测度群落总复杂性,用Shannon-Wiener熵H(S)=-q/∑/j=1p  相似文献   

18.
This is an ethnobotanical study of Atlantic Forest coastal communities located at Sepetiba Bay, Rio de Janeiro State, Brazil. Atlantic Forest remnants are top priority conservation areas, and include native communities that depend on fish and small-scale agriculture. We conducted fieldwork in the community of Calhaus (Jaguanum Island) from 1989 to 1991, and interviewed adults on their use of plants. We examined the diversity of medicinal plants used among communities of different islands and found results similar to previous research at Gamboa (Itacuruçá Island); communities living in smaller islands and on islands further from the coast use a lower diversity of plants. Also, older islanders show a deeper knowledge of medicinal plants than younger islanders.  相似文献   

19.
天山南麓山前平原植物群落物种多样性及空间分异研究   总被引:2,自引:0,他引:2  
荒漠灌丛是天山南麓山前平原主要植被类型.本研究定量分析了山前平原植物群落物种多样性及生境尺度异质性的影响.结果表明:(1)天山南麓山前平原的植物群落多样性指数Simpson、均匀度指数McIntosh及丰富度指数Margalef都较低,在地貌带的过渡上,植物分布呈现均匀化.(2)海拔和地下水埋深是影响天山南麓山前平原植物群落物种多样性的重要环境指标.海拔梯度与物种多样性指数Simpson、Margalef及McIntosh均呈显著的线性正相关关系,物种多样性均随海拔高度的增加而增加;地下水埋深与物种多样性指数呈极显著的线性负相关关系,物种多样性随地下水埋深的增加而减小.(3)土壤含盐量与物种多样性指标无显著关系,但土壤含盐量与地下水埋深相关性显著,这是天山南麓山前平原土壤盐分空间异质性的一个重要特点.土壤盐分含量变化影响着植物群落物种组成,随土壤盐分含量增加,群落中盐生植物种类逐渐占据优势.(4)海拔的变化是决定天山南麓山前平原灌丛群落生境差异的主导因子.海拔差异表征了山前平原地貌、水文地质条件及土壤的变化,而随海拔变化的水热、水盐等干扰体系的差异则进一步导致了异质性的生境,进而影响不同植被类型中群落组成结构和多样性的差异.  相似文献   

20.
通过野外调查,对世界地质公园四川兴文石海的小岩湾代表性园区植物群落物种组成进行统计分析,结果表明,该园区共有植物48科82属90种,其中天坑物种最丰富(75种),3个溶蚀洼地52种,猴子潭种类最少(12种)。采用香农指数对几个植物群落物种的多样性进行比较,香农指数H'由高到低依次为:天坑(4.056) >溶蚀洼地Ⅰ(2.882) >溶蚀洼地Ⅱ(2.878) >猴子潭(2.821) >溶蚀洼地Ⅲ(2.258),表明天坑物种多样性指数最高,溶蚀洼地Ⅰ和Ⅱ其次,猴子潭地区物种多样性较低,溶蚀洼地Ⅲ最低。建议对石漠化地区植被和植物群落进行深入研究,同时加强对该区植被的保护力度。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号