共查询到20条相似文献，搜索用时 0 毫秒
1.
DAVID M. WATSON 《Austral ecology》2003,28(5):515-525
Abstract Bird surveys are among the most widely used biodiversity inventories and serve as the basis for an increasing proportion of pure and applied ecological research. It is rarely possible to conduct exhaustive censuses of all individuals present at a particular site, so stopping rules are routinely used to determine when sampling should finish. Most bird survey methods use (implicit) effort‐based stopping rules, either fixed times, fixed sampling areas (quadrats) or both, to standardize samples of different sites. If between‐site variation is high, however, a fixed sampling effort will generate samples of variable completeness with samples from smaller, less complex sites being more representative and complete than samples from larger, more complex sites. More importantly, quadrat‐based methods shift the scope of the overall study from bird occurrence in sites to bird occurrence in quadrats within sites, diminishing the impact of the research given that results cannot be extrapolated to relevant biological and management scales. Here I advocate an alternative means of conducting bird surveys, whereby the entire site is sampled and a results‐based stopping rule is used to ensure sample completeness is uniform across all sites. For example, a researcher may decide to continue sampling each site until two or fewer previously unencountered species are recorded in a 40‐min period. Samples of different sites will vary in both area and duration but will all be equivalently accurate estimates of species richness. This approach allows the avifauna of entire sites (whether territories, woodland remnants or catchments) to be sampled and compared directly, generating results and implications at the appropriate scale. In addition to yielding reliable measures of species richness, data collected this way can be used to calculate estimates of sample completeness and species incidence, two valuable metrics for ecological studies. This paper includes detailed worked examples of how to conduct a ‘standardized search’ and calculate sample completeness and species incidence estimates. I encourage further research on bird survey methods, and suggest that most current methods are insufficient, inconsistent and unreliable. 相似文献
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P. Corona C. Blasi G. Chirici L. Facioni L. Fattorini B. Ferrari 《Plant biosystems》2013,147(1):171-179
Abstract Forest inventories are evolving towards multipurpose resource surveys, broadening their scope by including additional topics such as biodiversity issues. Surprisingly, few quantitative surveys have been devoted to old‐growth forests, even if they constitute the most acknowledged forest biodiversity icons. In this framework, the use of probabilistic sampling may provide an effective as well as rigorous support for monitoring and assessing old‐growth forests. To this purpose, the present paper proposes a two‐phase sampling scheme. In the first phase, a coarse survey of few floristic and stand structural attributes is carried out by means of small plots systematically placed on the study area. Subsequently, in the second phase, a fine assessment of a large number of ecological attributes is performed on a subset of enlarged plots selected among the first‐phase ones by means of simple random sampling without replacement. The proposed sampling scheme is implemented for monitoring and assessing the old forests of Cilento National Park (southern Italy). Results and comments are provided as an exemplicative case study. 相似文献
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C. B. De Araújo;M. R. Lima;P. Albuquerque;R. D. Alquezar;M. Barreiros;M. Jardim;E. Gangenova;R. B. Machado;B. T. Phalan;A. L. Roos;G. L. M. Rosa;N. Saturnino;C. R. Simões;I. M. D. Torres;D. Varela;J. P. Zurano;P. A. M. Marques;L. dos Anjos; 《Biotropica》2024,56(3):e13307
Passive acoustic monitoring (PAM) is increasingly popular in ecological research, but recording and analyzing large amounts of data is still a critical bottleneck for the long-term monitoring of multiple species. We evaluated how temporal and spatial sampling effort affects species diversity estimates using a set of 14,045 1-min recordings from various neotropical birds and anuran communities. Our goals were to evaluate (i) the daily vocal activity cycle of birds and anurans, (ii) the effect of temporal structure (e.g., number of minutes listened each hour; continuous versus intermittent recordings) on determining the species composition, and (iii) the species–area relationship, and how the number of recorders affects species richness estimates. Based on sampling coverage and completeness, we (iv) evaluate manual inspection schedules for birds and anurans across four biomes of Brazil. We found marked diel variation in vocal activity between taxonomic groups, indicating that birds and anurans are more efficiently detected during early periods of the day and night, respectively. For proper diversity estimates, biomes with higher biodiversity required longer inspecting periods and a larger number of replicates, irrespective of taxa. Although fewer recordings per hour are less informative than full-hour sampling, species diversity is better estimated when inspected minutes are interspersed over longer periods than inspecting minutes recorded over shorter timespans. Based on our findings, we recommend how to set PAM programs over highly diverse ecosystems. 相似文献
4.
Abstract: Little quantitative information exists about the survey effort necessary to inventory temperate bat species assemblages. We used a bootstrap resampling algorithm to estimate the number of mist net surveys required to capture individuals from 9 species at both study area and site levels using data collected in a forested watershed in northwestern California, USA, during 1996–2000. The mean number of simulated surveys required to capture individual species varied with species' rarity and ranged from 1.5 to 44.9. We retrospectively evaluated strategies to reduce required survey effort by subsampling data from 1996 to 1998 and tested the strategies in the field during 1999 and 2000. Using data from 1996 to 1998, the mean number of simulated surveys required to capture 8 out of 9 species was 26.3, but a 95% probability of capture required >61 surveys. Inventory efficiency, defined as the cumulative proportion of species detected per survey effort, improved for both the study area and individual sites by conducting surveys later in summer. We realized further improvements in study area inventory efficiency by focusing on productive sites. We found that 3 surveys conducted between 1 July and 10 September at each of 4 productive sites in this 10-km2 study area resulted in the capture of 8 species annually. Quantitative estimation of the survey effort required to assess bat species occurrence improves the ability to plan and execute reliable, efficient inventories. Results from our study should be useful for planning inventories in nearby geographical areas and similar habitat types; further, the analytical methods we used to assess effort are broadly applicable to other survey methods and taxa. 相似文献
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Xue Yao;Zun Dai;Yiran Wang;Jian Zhang;Jian Wang; 《Ecology and evolution》2024,14(11):e70593
Knowing the total number of species in a region has been a question of great interest motivated by the need to provide a reference point for current and future losses of biodiversity. Unfortunately, obtaining an accurate number is constrained by the fact that most species remain to be discovered, due to the imperfect detection of species in the field collection or because of temporal turnover in species composition. Here, to understand the inventory completeness at the local scale, we studied the temporal dynamics in the species richness and composition of bryophytes in Tianmushan National Nature Reserve. We used β-diversity to measure the temporal variation and analyzed the species attributes of newly discovered species collected this time. Furthermore, we evaluated our sampling strategy to measure sampling effect and estimated the species that remain to be discovered. We found that total β-diversity was largely driven by turnover. The analysis of species attributes showed that epiphytic species dominate the newly recorded species in both the narrow and wide elevational range species. Further, if only one of the methods was adopted, 26%–29% of the newly discovered species would be missed, and we inferred that there are likely are 185 bryophytes yet to be discovered. Our results indicate that when the same effort was made, an appropriate sampling methodology is crucial to accelerate newly recorded species discovery. Further, the results of our study highlight that species temporal turnover should be considered when assessing the completeness of species inventories at the local scale. 相似文献
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Remote underwater videos are widely employed to assess the structure and composition of reef fish assemblages but the sampling effort employed on each survey differs considerably, indicating that both the number of assessments and video length could be optimized. We searched for this optimal sampling effort in remote video samples to conduct rapid assessments of community composition and discussed the relation between number of replicates and video length, and how it impacts the method's efficiency to characterize species assemblages. Remote video recordings from tropical reefs in northeastern Brazil were used to investigate how fish species richness and composition builds across time and number of assays. Videos as short as 5 min successfully recorded species richness, requiring about five repetitions to record most species that compose 80% of the total biomass. Recording species composition required even less time in these reefs, setting a minimum of 3 min with the same five videos. By comparing the detected richness per analysed time unit, we found several shorter videos recorded for more species than a few longer videos, indicating that increasing the sampling coverage in the reef area might be better than just extending the video length for rapid assessments. 相似文献
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GRAHAM G. THOMPSON SCOTT A. THOMPSON PHILIP C. WITHERS JASON FRASER 《Austral ecology》2007,32(5):570-580
Abstract Environmental impact assessments (EIA) require that the proponent indicates the potential impact that a development will have on the biodiversity of the area. As part of this assessment it is normal practice to inventory the vertebrate species in the area. We show here how species accumulation curves can be used as a tool by environmental consultants to indicate the adequacy of their trapping effort and predict species richness for a disturbance site. The shape of a species accumulation curve is influenced by the number of species in an assemblage and the proportional number of singletons (rarely caught species) in the survey sample. We provide guidelines for the number of individuals that need to be caught in a trapping program to achieve 80% and 90% of the species in a habitat, and we indicate how this number can be adjusted to accommodate variations in relative species abundance. 相似文献
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四川贡嘎山国家级自然保护区位于全球生物多样性热点地区之一的横断山区, 是我国生物多样性保护优先区。本文利用红外相机影像和已发表文献对该保护区的大中型兽类和地面活动鸟类进行编目并提出未来监测建议。2011-2018年在97个1 km × 1 km的网格安放红外相机, 累计39,881个相机日, 获得独立有效照片20,932张, 其中野生兽类16,244张, 鸟类2,775张, 牲畜1,737张, 人176张。鉴定出野生兽类30种, 另有文献报道4种和观察3种, 分属于5目15科; 鸟类78种, 分属于9目22科; 牲畜6种。包括12种国家I级和28种国家II级重点保护野生动物; 被CITES附录I收录的有11种, 附录II收录的有12种。被IUCN红色名录评估为濒危(EN)和易危(VU)等级的分别有3种和8种。被《中国脊椎动物红色名录》评估为极危(CR)、濒危和易危等级的分别有5、5和11种。相对多度指数(relative abundance index, RAI)排名前三的兽类是毛冠鹿(Elaphodus cephalophus, 147.39)、水鹿(Rusa unicolor, 66.10)、野猪(Sus scrofa, 36.03); 鸟类是血雉(Ithaginis cruentus, 14.64)、白马鸡(Crossoptilon crossoptilon, 10.43)、大噪鹛(Garrulax maximus, 8.05)。阔叶林、针阔混交林、高山灌丛草甸和高山流石滩是调查薄弱生境, 后期应开展重点调查, 以厘清本区域大中型兽类资源。 相似文献
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Duccio Rocchini Sergio Andreini Butini Alessandro Chiarucci 《Global Ecology and Biogeography》2005,14(5):431-437
Aim Inventorying plant species in an area based on randomly placed quadrats can be quite inefficient. The aim of this paper is to test whether plant species richness can be inventoried more efficiently by means of a spectrally‐based ordering of sites to be sampled. Location The study area was a complex wetland ecosystem, the Lake Montepulciano Nature Reserve, central Italy. This is one of the most important wetland areas of central Italy because of the diverse plant communities and the seasonal avifauna. Methods Field sampling, based on a random stratified sampling design, was performed in June 2002. Plant species composition was recorded within sampling units of 100 m2 (plots) and 1 ha (macroplots). A QuickBird multispectral image of the same date was acquired and corrected both geometrically and radiometrically. Species accumulation curves based on spectral information were obtained by ordering sites to be sampled according to a maximum spectral distance criterion (i.e. by ordering sampling units based on the maximum distances among them in a four‐dimensional spectral space derived from the remotely sensed data). Different distance measures based on mean and maximum spectral distances among sampling units were tested. The performance of the species accumulation curve derived by the spectrally‐based ordering of sampling units was tested against a rarefaction curve obtained from the mean of 10,000 accumulation curves based on randomly ordered sampling units. Results The spectrally‐derived curve based on the maximum spectral distance among sampling units showed the most rapid accumulation of species, well above the rarefaction curve, at both the plot and the macroplot scales. Other ordering criteria of sampling units captured less richness over most of the species accumulation curves at both the spatial scales. The accumulation curves based on other measurements of distance were much closer to the random curve and did not show differences with respect to the species rarefaction curve based on random ordering of sampling units. Main conclusions The present investigation demonstrated that spectral‐based ordering of sites to be sampled can lead to the maximization of the efficiency of plant species inventories, an activity usually driven by the ‘botanist's internal algorithm’ (intuition), without any formalized rule to drive field sampling. The proposed approach can reduce costs of plant species inventorying through a more efficient allotment of time and sampling. 相似文献
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用种面积曲线和群落系数面积曲线的方法对宜昌梅子垭地区一种主要植物群落类型的最小面积进行了研究。结果表明,对所研究的植被类型,样地布置为 １０ｍ ×１０ｍ 及２０ｍ ×２０ｍ 可满足不同研究精度的要求。群落系统面积曲线和种面积曲线一样,比较直观。虽然取样调查时工作量稍大,但运用群落系数面积曲线的方法可更多地包含种类组成及群落结构随面积而变化的信息,所确定的最小面积也能够真实地反映整个群落种类组成及结构的特征。 相似文献
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为了探讨绿化植物生活型构成对边坡植被物种多样性及护坡性能的影响, 揭示生活型构成-群落特征-物种多样性-生态系统功能间的内在联系, 借助三物种组装实验, 分别构建以草本、灌木或乔木为主体的草本型(HHXi)、灌木型(SSXi)、乔木型(AAXi)或草-灌-乔混合型(HSA)配置模式的实验小区, 对实验区内边坡植被的群落特征、护坡性能进行持续4年的生态监测。结果表明: (1)边坡植被的物种丰富度与绿化植物生活型构成有关, AAXi的物种丰富度总体高于其他模式, 呈AAXi > SSXi > HSA > HHXi趋势。(2)不同配置模式边坡植被的群落盖度不一样, 年际间差异显著: 建坪初期(2010-2011年), HHXi的群落盖度远高于其他模式, HSA次之, AAXi最低; 2012-2013年间, HSA的群落盖度最高, HHXi次之, AAXi最低。(3)边坡植被的Shannon-Wiener指数、Pielou指数与绿化植物生活型构成有关, 其变化规律与群落盖度类似: 建坪初期, HHXi的多样性水平远高于其他模式, 呈HHXi > HSA > SSXi > AAXi趋势; 之后, 呈HSA > HHXi > SSXi > AAXi趋势。(4)边坡植被的护坡性能与群落内的物种多样性密切相关: 多样性水平越高, 护坡性能越强。可见, 在生态护坡过程中, 绿化植物生活型构成对提高边坡植被物种多样性、改善护坡性能至关重要。 相似文献
14.
海南石梅湾青皮林最小取样面积与物种多样性研究 总被引：15，自引：0，他引：15
石梅湾海岸青皮(Vatica hainanensis)林是海南独特的雨林群落之一。本文选用8种“种-面积渐近线”对该群落的最小取样面积进行了拟合研究。结果表明,其中5条曲线的R^2大于0．97,拟合状况很好,但所得出的最小取样面积各不相同。进一步经过“重要值-面积曲线”的群落特征分析,确认群落的最小取样面积只有800m^2。石梅湾青皮林最小取样面积比海南其他类型雨林、滇南热带雨林、东南亚热带雨林以及非洲雨林都要小。通过对1000m^2样地的物种多样性分析,结果表明：在垂直结构上,石梅湾青皮林B层乔木的Gleason指数大于A层乔木,和海南山地雨林的情况不同。海岸青皮林为物种多样性不高的单优林,群落的物种多样性、均匀度远小于海南其他类型的山地雨林与混合青皮林;在海岸青皮林群落内,青皮的相对密度、相对优势度、重要值大大高于其他物种。此研究表明：海南热带雨林同样存在物种多样性不高、单优特征显著的顶极群落;海南海岸青皮林是迄今为止热带雨林取样面积最小的森林类型。 相似文献
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Jeffrey J. Gerwing Stefan A. Schnitzer Robyn J. Burnham Frans Bongers Jrme Chave Saara J. DeWalt Corneille E. N. Ewango Robin Foster David Kenfack Miguel Martínez‐Ramos Marc Parren N. Parthasarathy Diego R. Prez‐Salicrup Francis E. Putz Duncan W. Thomas 《Biotropica》2006,38(2):256-261
A recent increase in published studies of lianas has been paralleled by a proliferation of protocols for censusing lianas. This article seeks to increase uniformity in liana inventories by providing specific recommendations for the determination of which taxa to include, the location of diameter measurement points on individual stems, the setting of minimum stem diameter cutoffs, the treatment of multiple‐stemmed and rooted clonal groups, and the measurement of noncylindrical stems. Use of more uniform liana censusing protocols may facilitate comparison of independently collected data sets and further our understanding of global patterns in liana abundance, diversity, biomass, and dynamics. 相似文献
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Nele Ingerpuu Kai Vellak Toomas Kukk Meelis Pärtel 《Biodiversity and Conservation》2001,10(12):2153-2166
We compare species richness of bryophytes and vascular plants in Estonian moist forests and mires. The material was collected from two wetland nature reserves. Bryophyte and vascular plant species were recorded in 338 homogeneous stands of approximately 1 ha in nine forest and two mire types. Regional species pools for bryophytes and vascular plants were significantly correlated. The correlations between the species richnesses of bryophytes and vascular plants per stand were positive in all community types. The relative richnesses (local richness divided by the regional species pool size) were similar for bryophyte species and for vascular plant species. This shows that on larger scales, conservation of the communities rich in species of one taxonomic plant group, maintains also the species richness of the other. The minimum number of stands needed for the maintenance of the regional species pool of typical species for the every community type was calculated using the species richness accumulation curves. Less stands are needed to maintain the bryophyte species pools (300–5300 for bryophytes and 400–35 000 for vascular plants). 相似文献
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Using the Southern African Bird Atlas Project (SABAP2) as a case study, we examine the possible determinants of spatial bias in volunteer sampling effort and how well such biased data represent environmental gradients across the area covered by the atlas. For each province in South Africa, we used generalized linear mixed models to determine the combination of variables that explain spatial variation in sampling effort (number of visits per 5′ × 5′ grid cell, or “pentad”). The explanatory variables were distance to major road and exceptional birding locations or “sampling hubs,” percentage cover of protected, urban, and cultivated area, and the climate variables mean annual precipitation, winter temperatures, and summer temperatures. Further, we used the climate variables and plant biomes to define subsets of pentads representing environmental zones across South Africa, Lesotho, and Swaziland. For each environmental zone, we quantified sampling intensity, and we assessed sampling completeness with species accumulation curves fitted to the asymptotic Lomolino model. Sampling effort was highest close to sampling hubs, major roads, urban areas, and protected areas. Cultivated area and the climate variables were less important. Further, environmental zones were not evenly represented by current data and the zones varied in the amount of sampling required representing the species that are present. SABAP2 volunteers' preferences in birding locations cause spatial bias in the dataset that should be taken into account when analyzing these data. Large parts of South Africa remain underrepresented, which may restrict the kind of ecological questions that may be addressed. However, sampling bias may be improved by directing volunteers toward undersampled regions while taking into account volunteer preferences. 相似文献
19.
The species accumulation curve, or collector’s curve, of a population gives the expected number of observed species or distinct classes as a function of sampling effort. Species accumulation curves allow researchers to assess and compare diversity across populations or to evaluate the benefits of additional sampling. Traditional applications have focused on ecological populations but emerging large-scale applications, for example in DNA sequencing, are orders of magnitude larger and present new challenges. We developed a method to estimate accumulation curves for predicting the complexity of DNA sequencing libraries. This method uses rational function approximations to a classical non-parametric empirical Bayes estimator due to Good and Toulmin [Biometrika, 1956, 43, 45–63]. Here we demonstrate how the same approach can be highly effective in other large-scale applications involving biological data sets. These include estimating microbial species richness, immune repertoire size, and k-mer diversity for genome assembly applications. We show how the method can be modified to address populations containing an effectively infinite number of species where saturation cannot practically be attained. We also introduce a flexible suite of tools implemented as an R package that make these methods broadly accessible. 相似文献
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根据群落物种数目估计的结果,并利用１０条种－面积曲线对东灵山地区几个类型植物群落的临界抽样面积进行了研究,并与其它几个群落最小面积的确定方法进行了比较。结果发现用各种方法确定的临界抽样面积是不同的,并且各种方法受种－面积曲线不同形式影响的程度也不同,但方法１受的影响最小,其意义比较直观、明确,由它得到的结果也比较可靠。对５个群落来说,要抽到这５个群落的乔、灌、草及整个群落６０％的种所需的临界抽样面积分别为３２５～５２５ｍ２（１３～２１个５ｍ×５ｍ的样方）、１００～５００ｍ２（４～２０个样方）、１７５～２７５ｍ２（７～１１个样方）和２２５～３５０ｍ２（９～１４个样方）。 相似文献