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Oscar B. Vitorino Júnior Rodrigo Fernandes Carlos S. Agostinho Fernando M. Pelicice 《Freshwater Biology》2016,61(10):1733-1745
- Riverine metacommunities have been studied mainly in streams and headwaters, and little is known about how dendritic networks affect metacommunity structure in large river systems. We, therefore, examined fish assemblages in the Upper Tocantins River, Amazon Basin, to investigate the hypothesis that riverine networks constrain metacommunity structure. In particular, we investigated (i) taxonomic and functional β‐diversity along the river channel (main stem) and major tributaries (branches); (ii) the relative importance of the turnover and nestedness components; and (iii) the relationship between β‐diversity and spatial structure (the distance decay of similarity).
- Fish assemblages were sampled over a year (2007–2008) at 17 sites distributed along the main stem (n = 8) and branches (n = 9). We recorded 170 fish species in the 100‐km river section studied. Local species richness ranged from 45 to 79, with higher mean values in the main stem; local assemblages, however, showed high functional richness, with no significant difference between the main stem and branches.
- We observed that the turnover component contributed 87.7% of the variation in taxonomic β‐diversity (Jaccard), while the nestedness‐resultant contributed 12.3%. Taxonomic β‐diversity was on average 2.5 times higher than functional diversity, and taxonomic turnover was on average four times greater than functional turnover. In addition, a null model showed that observed values of functional β‐diversity were not different from random expectations, given the observed level of taxonomic β‐diversity. Branches showed higher species turnover, while significant distance decay of similarity was observed only along the main stem. Functional β‐diversity was not different between the main stem and branches and did not correlate with watercourse distance.
- Our study revealed that fish metacommunity in this large river shows species turnover, but with high functional similarity. In addition, different β‐diversity patterns between the main stem and branches indicate that the dendritic network constrained metacommunity structure. Mass effects and dispersal limitations probably explain β‐diversity patterns in the main stem, while a combination of mechanisms (i.e., disturbance, specific biological functions and dispersal constraints) affect diversity in the branches.
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To restore diversity of native vegetation, we must understand factors responsible for diversity in targeted communities. These factors operate at different spatial scales and may affect the number and relative abundances of species differently. We measured diversity of plant species and functional groups of species in replicated plots within paired restored and remnant (relic) tallgrass prairies at three locations in central Texas, U.S.A. To determine the contributions of species abundances and of spatial patterns of diversity to differences between prairie types, we separated diversity into richness and evenness (relative biomass) and into within‐plot (α), among‐plot (β), and prairie (γ) components. Species diversity was greater in remnant than in restored prairies at all spatial scales. At the γ scale, both species richness and species evenness were greater in remnants because of greater spatial variation in species composition. At the α scale, remnants were more diverse because of greater richness alone. Mean α richness correlated positively with the size of the species pool in restored prairies only, implying that in remnants, α richness was influenced more by colonization dynamics than by the number of species available for colonization. Plots in remnant prairies contained more functional groups and fewer species per group than did plots in restored prairies, suggesting that resource partitioning was greater in relic prairies. Our results are consistent with the interpretation that local ecological processes, like resource partitioning and limitations on seed dispersal, contribute to the greater diversity of remnant than restored prairies in central Texas. Restoration practices that limit abundances of competitive dominants, increase the number of species in seed mixtures, and increase the proximity of plants of different functional groups thus may be required to better simulate the plant diversity of tallgrass prairies. 相似文献
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Bia A. Almeida Esther Sebastián-González Luiz dos Anjos Andy J. Green 《Freshwater Biology》2020,65(12):2196-2210
- The restoration of degraded areas and the creation of artificial ecosystems have partially compensated for the continuing loss of natural wetlands. However, the success of these wetlands in terms of the capacity of supporting biodiversity and ecosystem functions is unclear. Research is needed to improve our understanding of the value of restored and constructed wetlands for functional diversity of freshwater fauna.
- We compared natural, restored, and artificially created wetlands present within the Doñana Natural Space, Spain and valued as important for waterbirds. We evaluated if these wetlands are equivalent in terms of waterbird functional trait diversity and composition, during both the wintering and breeding seasons. We modelled functional diversity measures and functional group species richness describing species diet, body mass, and foraging techniques with generalised linear mixed models in 20 wetlands monitored between 2006 and 2011. We used three different statistical approaches to evaluate the robustness of our results.
- Artificial wetlands constructed for conservation failed to reach the functional diversity of natural and restored wetlands. Unexpectedly, artificial ponds constructed for fish production performed better, and even exceeded natural wetlands for functional richness during winter. Fish ponds stood out as having a unique functional composition, connected with increase in richness of opportunistic gulls and decrease of species sensitive to high salinity. Overall, the functional structure of breeding communities was more affected by wetland type than wintering communities.
- Our findings suggest that compensating the loss of natural wetlands with restored and artificial wetlands results in systems with altered waterbird-supported functions, such as seed dispersal or nutrient cycling. Protection of natural Mediterranean wetlands is vital to maintain the original diversity and composition of waterbird functional traits. Furthermore, restoration must be prioritised over the creation of artificial wetlands, which, even when intended for conservation, may not provide an adequate replacement.
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Human activities are causing a rapid loss of biodiversity, which impairs ecosystem functions and services. Therefore, understanding which processes shape how biodiversity is distributed along spatial and environmental gradients is a first step to guide conservation and management efforts. We aimed to determine the relative explanatory importance of biogeographic, environmental, landscape and spatial variables on assemblage dissimilarities and functional diversity of dung beetles along the Atlantic Forest–Pampa (i.e. forest–grassland) transition zone located in Southeast South America. We described each site according to their biogeographic position, environmental conditions, landscape features and spatial patterns. The compositional dissimilarity was partitioned into turnover and nestedness components of β‐diversity. Mantel tests and generalised dissimilarity models were used to relate β‐diversity and its components to biogeographic, environmental, landscape and spatial variables. Variation partitioning analysis was used to estimate the pure and shared variation in species composition and functional diversity explained by the four categories of predictors. Biome domain was the main factor causing dung beetle compositional dissimilarity, with a high species replacement between Atlantic Forest and Pampa. Biogeographic, environmental, landscape and spatial distances also affected the patterns of dung beetle dissimilarity and β‐diversity components. The shared effects of the four sets of predictors explained most of the variation in dung beetle composition. A similar response pattern was found for dung beetle functional diversity, which excluded biogeographic effects. Only the pure effects of environmental and spatial predictors were significant for species composition and functional diversity. Our results indicate that dung beetle species composition and functional diversity are jointly driven by environmental, landscape and spatial predictors with higher pure environmental and spatial effects. The forest–grassland transition zone promotes a strong species and trait replacement highly influenced both by environmental filtering and dispersal limitation. 相似文献
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Michael J. Lawes Anthony M. Moore Alan N. Andersen Noel D. Preece Donald C. Franklin 《Ecology and evolution》2017,7(20):8442-8455
Ecosystem restoration can help reverse biodiversity loss, but whether faunal communities of forests undergoing restoration converge with those of primary forest over time remains contentious. There is a need to develop faunal indicators of restoration success that more comprehensively reflect changes in biodiversity and ecosystem function. Ants are an ecologically dominant faunal group and are widely advocated as ecological indicators. We examine ant species and functional group responses on a chronosequence of rainforest restoration in northern Australia, and develop a novel method for selecting and using indicator species. Four sampling techniques were used to survey ants at 48 sites, from grassland, through various ages (1–24 years) of restoration plantings, to mature forest. From principal components analysis of seven vegetation metrics, we derived a Forest Development Index (FDI) of vegetation change along the chronosequence. A novel Ant Forest Indicator Index (AFII), based on the occurrences of ten key indicator species associated with either grassland or mature forest, was used to assess ant community change with forest restoration. Grasslands and mature forests supported compositionally distinct ant communities at both species and functional levels. The AFII was strongly correlated with forest development (FDI). At forest restoration sites older than 5–10 years that had a relatively closed canopy, ant communities converged on those of mature rainforest, indicating a promising restoration trajectory for fauna as well as plants. Our findings reinforce the utility of ants as ecological indicators and emphasize the importance of restoration methods that achieve rapid closed‐canopy conditions. The novel AFII assessed restoration status from diverse and patchily distributed species, closely tracking ant community succession using comprehensive species‐level data. It has wide applicability for assessing forest restoration in a way that is relatively independent of sampling methodology and intensity, and without a need for new comparative data from reference sites. 相似文献
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Quantifying rotifer species richness in temperate lakes 总被引：2，自引：0，他引：2
1. Biodiversity assessments of lakes depend on the ability to identify the complement of species present, although the degree of sampling required is often uncertain. We utilise long‐term data to predict rotifer species richness in three habitats in three Polish lakes using rarefaction sampling methods. 2. Richness in littoral and psammon habitats did not saturate, even with up to 130 samples. Highest richness was observed in psammon habitat (119 species) in Lake Mikolajskie, followed by littoral habitat in Lakes ?uknajno (114 species) and Kuc (110 species). Littoral habitats in Lakes ?uknajno (56%) and Kuc (51%) had the most species not shared with other habitats in the same lake. 3. Species richness (Chao2) estimates ranged between 44 for pelagic and 135 for psammon habitat in Lake Mikolajskie, to 100 for psammon and 137 for littoral habitat in Lake Kuc, and 65 for pelagic and 162 for littoral habitat in Lake ?uknajno. Whole lake estimates were 167, 205 and 171 species, respectively, for these lakes, higher than the 150 to 160 species predicted by Dumont and Segers (Hydrobiologia, 1996, 341 , 125). 4. Using standardised sampling, richness was significantly higher in littoral than either pelagic or psammon habitats. Contrasts of standardised rarefaction curves revealed that richness in Lakes Kuc and Mikolajskie was described as well by littoral‐only or psammon‐only samples, respectively, as by those randomly drawn from across all habitats in the lake. 5. Species richness estimates for Lake Mikolajskie were highest in summer, followed by autumn and spring. Interannual estimates differed by up to 427%, nearly an order of magnitude greater than maximal seasonal variation of 70%. 6. Results indicate that much higher sampling intensity is required to establish species richness than is presently carried out in most lakes. Because many species can be detected only with very intensive sampling, conservation programmes must consider sampling intensity when designing studies. 相似文献
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进入21世纪以来, 中国荒漠化恢复取得显著成效, 荒漠化、沙化土地面积持续减少, 植被覆盖度大幅提升, 但关于植被恢复过程中生物多样性如何变化的研究不足, 这制约着对荒漠化恢复成效的全面评估。本文基于群落调查和叶功能性状(叶片厚度、叶片干物质含量、比叶面积和叶片密度)的测定, 分析了毛乌素沙地不同恢复阶段(半固定沙地、固定沙地、结皮覆盖沙地和草本植物覆盖沙地)的植物群落物种多样性、功能多样性和系统发育多样性特征。结果表明: (1)多数叶功能性状的系统发育信号不显著, 表明环境因子对研究区植物功能性状的塑造作用很强。(2)对于α多样性, 结皮覆盖沙地的物种多样性(Shannon-Wiener多样性, H)、物种丰富度(S)、功能丰富度(FRic)及系统发育多样性(PD)指数均显著低于其他恢复阶段, 而其他3个阶段间无显著差异; 这些指数间均显著正相关, 表明物种多样性、功能多样性和系统发育多样性在植被恢复过程中协同变化。(3) β多样性指数随恢复阶段间隔增加而逐渐增大, 表明物种组成、功能属性及系统发育关系随植被恢复持续变化, 且半固定沙地到固定沙地的群落物种组成、功能属性及系统发育关系更替最快, 导致群落间差异最大。(4)固定沙地、结皮覆盖沙地和草本植物覆盖沙地群落系统发育结构均趋向于发散, 表明竞争排斥是群落构建的主要驱动力; 而半固定沙地群落系统发育结构无一致规律, 表明群落构建可能受到生境过滤和竞争排斥的综合作用。研究结果可为植被建设与管理提供参考, 为毛乌素沙地生态保育和生物多样性的保护提供科学依据。 相似文献
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The ratio of species extinctions to introductions has been comparable for many insular assemblages, suggesting that introductions could have ‘compensated’ for extinctions. However, the capacity for introduced species to replace ecological roles and evolutionary history lost following extinction is unclear. We investigated changes in bird functional and phylogenetic diversity in the wake of extinctions and introductions across a sample of 32 islands worldwide. We found that extinct and introduced species have comparable functional and phylogenetic alpha diversity. However, this was distributed at different positions in functional space and in the phylogeny, indicating a ‘false compensation’. Introduced and extinct species did not have equivalent functional roles nor belong to similar lineages. This makes it unlikely that novel island biotas composed of introduced taxa will be able to maintain ecological roles and represent the evolutionary histories of pre‐disturbance assemblages and highlights the importance of evaluating changes in alpha and beta diversity concurrently. 相似文献
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采用野外空间多点同步取样,分析了高原鼠兔干扰对高寒草甸植物物种beta多样性和植物功能性状beta多样性的影响,确定了高原鼠兔干扰下高寒草甸植物物种和功能性状beta多样性的变化途径,分别提出了高原鼠兔干扰区域内,基于植物物种多样性和功能性状多样性的高寒草甸植物多样性维持策略。结果表明,高原鼠兔干扰使高寒草甸植物物种相似性显著降低了28.1%,植物功能相似性降低了28.7%。尽管高原鼠兔干扰没有改变高寒草甸植物物种和功能性状beta多样性的变化途径,且对植物物种和功能性状的嵌套组分不存在显著影响,但高原鼠兔干扰显著降低了植物物种和功能性状周转组分所占的比例,降幅分别为36.6%和34.3%。高原鼠兔干扰区域内,高寒草甸植物物种beta多样性的变化以周转为主导(周转占比81.4%;嵌套占比:18.6%),植物功能性状beta多样性的变化以嵌套为主导(嵌套占比64.9%;周转占比35.1%)。因此,针对划定的高原鼠兔干扰区,需要同时保护区域内所有高原鼠兔栖息地(多位点保护),以达到维持植物物种多样性的目的,而可以仅通过保护该区域内植物功能性状丰富的位点,即可维持较高的植物功能多样性。 相似文献
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化学除草剂对农田生态系统野生植物多样性的影响 总被引：3，自引：0，他引：3
农田生物多样性是全球生物多样性的重要组成部分, 除草剂的大量施用对其产生了严重影响。本文综述了化学除草剂对农田生态系统中野生植物多样性的影响, 并分析归纳了其影响机制。除草剂的施用会使敏感植物减少, 抗药性植物增多, 从而改变农田生态系统中的野生植物物种组成, 并使其趋同化, 降低遗传多样性和物种多样性, 以致植物功能群单一化, 群落稳定性下降。除草剂的主要影响机制是杀死植物或改变其生长代谢、抗性、繁殖等, 改变生境, 并与人为因素、环境因素等产生协同影响。不同种类的除草剂影响程度不同, 且不同物种间、不同群落间的响应也存在差异。我国化学除草剂使用量持续增长, 应加强除草剂对野生植物多样性的影响及其机制研究, 重视除草剂使用历史记录和野生植物的长期监测, 以及除草剂使用规范和相关政策法律研究, 更好地保护我国农田生态系统中的生物多样性。 相似文献
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Steven T. Kalinowski 《Conservation Genetics》2004,5(4):539-543
The number of alleles (allelic richness) in a population is a fundamental measure of genetic variation, and a useful statistic for identifying populations for conservation. Estimating allelic richness is complicated by the effects of sample size: large samples are expected to have more alleles. Rarefaction solves this problem. This communication extends the rarefaction procedure to count private alleles and to accommodate hierarchical sampling designs. 相似文献
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稀有种是海洋生态系统中物种共存与多样性维持的重要类群,但其对鱼类群落物种多样性、功能多样性的调控机制不明。以三门湾鱼类群落为研究对象,基于地理范围、栖息地特异性和种群规模大小识别群落稀有种,利用自抽样技术模拟稀有种在自然条件下的随机丧失,探讨稀有种丧失对物种多样性、功能多样性的影响。结果表明,稀有种的丧失造成物种丰富度与功能丰富度呈显著下降趋势;物种均匀度在夏季稳定性较低,在其余季节稳定性较高,功能均匀度在冬季稳定性较高,在其余季节稳定性较低,这与稀有种地理分布范围及其功能性状所占据的空间特殊位置有关;Simpson指数与Shannon-Wiener指数呈现下降趋势,但前者数值变化区间小于后者,这与群落丰富度、均匀度密切相关;功能离散度在夏季呈下降趋势,而在其他季节保持相对稳定,主要受位于性状空间边缘物种数量的影响。总体上,稀有种的丧失对物种多样性、功能多样性的稳定性产生影响,且物种多样性与功能多样性的相关性较强。 相似文献
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Functional diversity is an important component of biodiversity, yet in comparison to taxonomic diversity, methods of quantifying functional diversity are less well developed. Here, we propose a means for quantifying functional diversity that may be particularly useful for determining how functional diversity is related to ecosystem functioning. This measure of functional diversity “FD” is defined as the total branch length of a functional dendrogram. Various characteristics of FD make it preferable to other measures of functional diversity, such as the number of functional groups in a community. Simulating species' trait values illustrates how the relative importance of richness and composition for FD depends on the effective dimensionality of the trait space in which species separate. Fewer dimensions increase the importance of community composition and functional redundancy. More dimensions increase the importance of species richness and decreases functional redundancy. Clumping of species in trait space increases the relative importance of community composition. Five natural communities show remarkably similar relationships between FD and species richness. 相似文献
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Pedro H. S. Brancalion Ricardo A. G. Viani James Aronson Ricardo R. Rodrigues André G. Nave 《Restoration Ecology》2012,20(6):704-711
High‐diversity reforestation can help jumpstart tropical forest restoration, but obtaining viable seedlings is a major constraint: if nurseries do not offer them, it is hard to plant all the species one would like. From 2007 to 2009, we investigated five different seed acquisition strategies employed by a well‐established tree nursery in southeastern Brazil, namely (1) in‐house seed harvesters; (2) hiring a professional harvester; (3) amateur seed harvesters; or (4) a seed production cooperative, as well as (5) participating in a seed exchange program. In addition, we evaluated two strategies not dependent on seeds: harvesting seedlings from native tree species found regenerating under Eucalyptus plantations, and in a native forest remnant. A total of 344 native tree and shrub species were collected as seeds or seedlings, including 2,465 seed lots. Among these, a subset of 120 species was obtained through seed harvesting in each year. Overall, combining several strategies for obtaining planting stocks was an effective way to increase species richness, representation of some functional groups (dispersal syndromes, planting group, and shade tolerance), and genetic diversity of seedlings produced in forest tree nurseries. Such outcomes are greatly desirable to support high‐diversity reforestation as part of tropical forest restoration. In addition, community‐based seed harvesting strategies fostered greater socioeconomic integration of traditional communities in restoration projects and programs, which is an important bottleneck for the advance of ecological restoration, especially in developing countries. Finally, we discuss some of the limitations of the various strategies for obtaining planting stocks and the way forward for their improvement. 相似文献
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杭州西溪湿地是在自然湿地基础上,并在一千多年农渔耕作用下形成的城市边缘次生湿地。随着工业化和城市化,它的面积急剧萎缩,植被受 干扰,生态脆弱,不久前成立的西溪国家湿地公园已经将保护提上日程。该文在报道这类特殊湿地植被结构和物种多样性的基础上试图回答下 列问题：何种小生境利于保护本地和湿地植物多样性？入侵种在各种小生境中的影响如何？怎样防控？根据调查,将西溪湿地草本层的小生境 分成5种类型：强光高基、弱光(有树遮光)高基、强光低基、强光高渚和强光低渚。采用分层和随机取样相结合的方法调查这5种小生境下的植 物群落组成,以重要值作为变量来计算物种多样性指数并排序。共26个地点,约234 m2的样方。结果显示在农渔耕的背景下,水位高低及光照 等自然因子对植物组成具有一定的选择作用。强光高基生境物种丰富度最高,其中本土、木本和豆科植物数量最多,而入侵种、湿生物种数量 最低;强光低渚生境的情况正好相反。强光高基生境有利于保持本土植物多样性,降低入侵种的竞争能力,但不利于湿地植物的存在;强光低 基有中度本土植物多样性及抵御入侵种的能力,有较大的草本比例和湿地植物比例,是一个保持良好的湿地环境。有利于湿地植物的低湿生境 目前在西溪比例较低,湿地植物偏少,这主要与西溪先前人类从事农业和渔业活动有关。在去除影响景观、影响本土物种多样性的入侵种的同 时,可考虑增加低湿的生境,并补种湿地物种。 相似文献
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We sampled small mammal assemblage in a mosaic of Valley Thicket vegetation in the Great Fish River Reserve during the summers of 2001 and 2002. Assemblage was dominated by seven rodent species with a single nonrodent species (Elephantulus edwardii) in the 357 trapped specimens. Rhabdomys dilectus was the most abundant in both years, followed by Mus minutoides (ranking 2nd in 2001) and Mastomys coucha (2nd in 2002). These three species, which are widespread generalists, made up 85.0% of the total rodent catch in 2001 and 74.3% in 2002. Individual species were captured on 2–14 sites of a total of 17 and M. minutoides was the most widespread. The majority of samples consisted of two (ten sites in a pooled sample for 2 years) or three species (ten sites). Significant morphological structuring was found only in two‐species samples. Species turnover was high both among sites and between the 2 years. We found no evidence of significant nested structure which would suggest hierarchical sets of ecological relationships among the species. Vegetation structure explained better than species interactions, the population variables in the rodent assemblage. 相似文献
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MATTHIAS VOLK PATRICK BUNGENER FRANÇOIS CONTAT MYRTA MONTANI JÜRG FUHRER 《Global Change Biology》2006,12(1):74-83
The sensitivity of seminatural grasslands to ozone (O3) pollution is not well known, in spite of the important function of these common ecosystems for agriculture and nature conservation. A 5‐year field experiment was carried out at a rural, mid‐elevation site at Le Mouret (Switzerland) to investigate the effect of elevated O3 on yield and species composition of a permanent, extensively managed, species‐rich old pasture. Using a free‐air fumigation system, circular plots of 7 m diameter were exposed to either ambient air (control plots) or to air containing O3 of approximately 1.5 × ambient concentrations. The resulting accumulated O3 exposure over the threshold of 40 ppb for one season ranged from 13.3 to 59.5 ppm h in the elevated O3 plots, and from 1.0 to 20.7 ppm h in the control plots. Subplots in each ring were harvested three times each year, and harvested biomass was separated into functional groups (FGs) (grasses, legumes, forbs). Productivity in both treatments decreased over time, but the yield of O3‐exposed plots decreased faster than that of the control plots, with the reduction being twice as large by the end of the fifth season. Compared with the ambient air control, loss in annual dry matter yield was 23% after 5 years. The change in annual biomass production because of O3 stress was accompanied by a change in the fractions of FGs, with the legume fraction showing a strong negative response. Such long‐term effects of O3 stress could have negative implications for the maintenance of biological diversity in rural landscapes across large areas of Europe. The results from this first long‐term experiment show that a moderately elevated O3 level reduces the productivity of intact grasslands during a 5‐year exposure under real field conditions. 相似文献