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Restricted adaptive cluster sampling 总被引:4,自引:0,他引:4
Adaptive cluster sampling can be a useful design for sampling rare and patchy populations. With this design the initial sample size is fixed but the size of the final sample (and total sampling effort) cannot be predicted prior to sampling. For some populations the final sample size can be quite variable depending on the level of patchiness. Restricted adaptive cluster sampling is a proposed modification where a limit is placed on the sample size prior to sampling and quadrats are selected sequentially for the initial sample size. As a result there is less variation in the final sample size and the total sampling effort can be predicted with some certainty, which is impor- tant for many ecological studies. Estimates of density are biased with the restricted design but under some circumstances the bias can be estimated well by bootstrapping. © Rapid Science 1998 相似文献
3.
Monitoring,imperfect detection,and risk optimization of a Tasmanian devil insurance population
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Tracy M. Rout Christopher M. Baker Stewart Huxtable Brendan A. Wintle 《Conservation biology》2018,32(2):267-275
Most species are imperfectly detected during biological surveys, which creates uncertainty around their abundance or presence at a given location. Decision makers managing threatened or pest species are regularly faced with this uncertainty. Wildlife diseases can drive species to extinction; thus, managing species with disease is an important part of conservation. Devil facial tumor disease (DFTD) is one such disease that led to the listing of the Tasmanian devil (Sarcophilus harrisii) as endangered. Managers aim to maintain devils in the wild by establishing disease‐free insurance populations at isolated sites. Often a resident DFTD‐affected population must first be removed. In a successful collaboration between decision scientists and wildlife managers, we used an accessible population model to inform monitoring decisions and facilitate the establishment of an insurance population of devils on Forestier Peninsula. We used a Bayesian catch‐effort model to estimate population size of a diseased population from removal and camera trap data. We also analyzed the costs and benefits of declaring the area disease‐free prior to reintroduction and establishment of a healthy insurance population. After the monitoring session in May–June 2015, the probability that all devils had been successfully removed was close to 1, even when we accounted for a possible introduction of a devil to the site. Given this high probability and the baseline cost of declaring population absence prematurely, we found it was not cost‐effective to carry out any additional monitoring before introducing the insurance population. Considering these results within the broader context of Tasmanian devil management, managers ultimately decided to implement an additional monitoring session before the introduction. This was a conservative decision that accounted for uncertainty in model estimates and for the broader nonmonetary costs of mistakenly declaring the area disease‐free. 相似文献
4.
为了解白鹤滩蓄水运行前黑水河下游鱼类资源的现状、受到的主要威胁及其保护措施,于2014年1~12月在黑水河下游干支流江段采用电捕法进行了渔获物调查。结果显示:12个月共调查发现鱼类28种,隶属于3目8科23属,其中喜流水生境、产粘沉性卵、以着生藻类或/和底栖动物为食物的鱼类种类较多;调查区域鱼类个体规格普遍较小,其中齐口裂腹鱼Schizothorax prenanti、短体副鳅Paracobitis potanini、红尾副鳅Paracobitis varigatus、短须裂腹鱼Schizothorax wangchiachii、前鳍高原鳅Triplophysa anterodorsalis、中华纹胸鮡Glyptothorax sinense和凹尾拟鲿Pseudobagrus emarginatus为调查区域的主要经济鱼类;上半年和下半年的渔获物结构在统计学上差异显著(R=0.81,p=0.1%0.05),鱼类在金沙江干流和黑水河下游之间的相互迁徙比较明显;CPUE呈现先波动下降然后逐月上升的趋势,其中10月份的CPUE最低;丰度生物量比较曲线显示2014年各月的渔获物结构均处于严重干扰状态。黑水河下游河道采砂以及过度捕捞是白鹤滩蓄水前影响黑水河下游鱼类资源的主要因素,建议通过控制采砂的江段、采砂的时间以及全面禁捕保护该区域的鱼类资源。 相似文献
5.
R. Hickisch T. Hodgetts P. J. Johnson C. Sillero-Zubiri K. Tockner D.W. Macdonald 《Conservation biology》2019,33(5):1151-1163
Conservation planners need reliable information on spatial patterns of biodiversity. However, existing data sets are skewed because some ecosystems, taxa, and locations are underrepresented. We determined how many articles have been published in recent decades on the biodiversity of different countries and their constituent provinces. We searched the Web of Science catalogues Science Citation Index (SCI) and Social Science Citation Index (SSCI) for biodiversity-related articles published from 1993 to 2016 that included country and province names. We combined data on research publication frequency with other provincial-scale factors hypothesized to affect the likelihood of research activity (i.e., economic development, human presence, infrastructure, and remoteness). Areas that appeared understudied relative to the biodiversity expected based on site climate likely have been inaccessible to researchers for reasons, notably armed conflict. Geographic publication bias is of most concern in the most remote areas of sub-Saharan Africa and South America. Our provincial-scale model may help compensate for publication biases in conservation planning by revealing the spatial extent of research needs and the low cost of redoing this analysis annually. 相似文献
6.
Citizen science may be especially effective in urban landscapes due to the large pool of potential volunteers. However, there have been few evaluations of the contributions of citizen scientists to knowledge of biological communities in and around cities. To assess the effectiveness of citizen scientists' monitoring of species in urban areas, we compared butterfly data collected over 10 years in Chicago, Illinois (U.S.A.), and New York City, New York (U.S.A.). The dates, locations, and methods of data collection in Chicago were standardized, whereas data from New York were collected at any location at any time. For each city, we evaluated whether the number of observers, observation days (days on which observations were reported), and sampling locations were associated with the reported proportion of the estimated regional pool of butterfly species. We also compared the number of volunteers, duration of volunteer involvement, and consistency of sampling efforts at individual locations within each city over time. From 2001 to 2010, there were 73 volunteers in Chicago and 89 in New York. During this period, volunteers observed 86% and 89% of the estimated number of butterfly species present in Chicago and New York, respectively. Volunteers in New York reported a greater proportion of the estimated pool of butterfly species per year. In addition, more species were observed per volunteer and observation day in New York, largely due to the unrestricted sampling season in New York. Chicago volunteers were active for more years and monitored individual locations more consistently over time than volunteers in New York. Differences in monitoring protocol--especially length of sampling season and selection protocol for monitoring locations--influenced the relationship between species accrual and sampling effort, which suggests these factors are important in volunteer-based species-monitoring programs. 相似文献
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8.
The Botanist Effect Revisited: Plant Species Richness, County Area, and Human Population Size in the United States 总被引:3,自引:0,他引:3
Abstract: The "botanist effect" is thought to be the reason for higher plant species richness in areas where botanists are disproportionately present as an artefactual consequence of a more thorough sampling. We examined whether this was the case for U.S. counties. We collated the number of species of vascular plants, human population size, and the area of U.S. counties. Controlling for spatial autocorrelation and county area, plant species richness increased with human population size and density in counties with and without universities and/or botanical gardens, with no significant differences in the relation between the two subsets. This is consistent with previous findings and further evidence of a broad-scale positive correlation between species richness and human population presence, which has important consequences for the experience of nature by inhabitants of densely populated regions. Combined with the many reports of a negative correlation between the two variables at a local scale, the positive relation between plant species richness in U.S. counties and human population presence stresses the need for the conservation of seminatural areas in urbanized ecosystems and for the containment of urban and suburban sprawl. 相似文献
9.
A total of 250 nestboxes were arranged in five plots in a suburban area of Budapest, Hungary (19°04E, 47°41N). In each plot, 25 were placed at 50 m intervals to simulate solitary breeding and 25 3–5 m apart to simulate colonial breeding. Length of nest building period, feeding frequency, nestling mortality, nestlings' diet, productivity and parental condition were compared for colonial and solitary breeding tree sparrows Passer montanus. Parents with long nest-building periods, including the majority of first-year females, produced fewer young than parents which built over short periods. Parents fed nestlings morefrequently and nestlings had lower mortality in second than first broods; whether or not a third brood was reared was determined by the costs invested in first and second broods. Females that laid a third clutch had reared fewer young in first and second broods and were heavier than females that reared many young in two broods. Colonial birds had higher feeding frequencies, more similar diets and suffered lower nestling mortality than solitary parents for first broods, but they fed less frequently, diets were less similar, and nestling mortality was higher in second and third broods. It is suggested that colonial breeders benefited from the social stimulation of simultaneous feeding in first broods, but the advantage of synchronicity in feeding declined in second broods and the sparser breeding spacing of solitary parents was more advantageous for feeding in second and third broods. Birds that changed nest spacing between broods had fed nestlings less frequently and had higher nestling mortality before changing than birds which retained their spacing. Parents which changed from colonies to solitary nests fed more frequently with lower nestling mortality in the next brood than parents which retained colonial nests for their second (and third) brood. Solitary parents did not show such a relationship. The rearing of three broods caused higher weight loss in colonial than solitary parents.Correspondence to: L. Sasvári 相似文献
10.
Abstract: Hunting in tropical forests is typically most intense near human settlements, and this creates gradients of decreasing animal densities toward those settlements. Within the context of this spatial pattern, we evaluated the status of game in the hunting grounds of an indigenous community in eastern Ecuador. We constructed a spatially explicit model of hunter-prey interactions that mimicked the hunting in the village and included realistic animal-dispersal rules. We compared predictions from the model with distributions of animal harvest rates and catch per unit effort of 12 game species. Six species were overharvested in part or all of the area, and two other species were probably being overharvested, although high dispersal rates complicated the interpretation. We then compared our method with methods that have been used previously. We argue that because our method provides information about the spatial extent of overharvesting, it could be particularly useful in informing decision makers about where to establish no-take areas and could therefore aid in improving the sustainability of hunting in tropical forests. 相似文献