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Attila Molnár V. Timea Nagy Viktor Löki Kristóf Süveges Attila Takács Judit Bódis Jácint Tökölyi 《Ecology and evolution》2017,7(24):11257-11264
Harvest of orchid tubers for salep production is widespread in southwestern Asia and the Balkans and constitutes a major conservation risk for wild orchid populations. Synanthropic habitats, such as graveyards, are important refuges for orchids and other organisms and could offer protection from salep harvesting because of their special cultural role. However, little is known about the occurrence and factors influencing harvesting of salep in graveyards. During field surveys of 474 graveyards throughout Turkey, we observed 333 graveyards with orchids, 311 graveyards with tuberous orchids, and salep harvest in 14 graveyards. Altogether, 530 individuals of 17 orchid species were collected, representing 9% of the individuals recorded. Harvesting intensity was relatively low, and populations were usually not wholly destroyed. However, some species were clearly more affected than others. Salep harvesting risk of orchid species was significantly associated with flowering time, with early‐flowering species being more affected. A marginally significant positive relationship between harvesting risk and species‐specific tuber size was also detected. Our data suggest that graveyards might offer some protection against salep harvesting in Turkey, but they also show that some orchid taxa are much more affected than others. Overall, our observations add more weight to the conservation value of these special habitats. 相似文献
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Bird censuses were taken by routing in the central part of the Prilenskoe plateau, a region poorly explored by ornithologists. The summer population of birds in different habitats at watersheds, in valleys and along riverbanks has been characterized on the basis of the original data obtained. 相似文献
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Steve Ahlswede Ezequiel Chimbioputo Fabiano Derek Keeping Klaus Birkhofer 《African Journal of Ecology》2019,57(2):177-189
Finding an appropriate method to monitor a wide range of mammal species simultaneously is notoriously difficult, as each method has its limitations. Here, we examine a formula, known as the Formozov–Malyshev–Pereleshin (FMP), which uses mean daily travel distances (day ranges) to convert spoor counts into density estimates. Availability of accurate estimates of day ranges is a limitation of the FMP formula. Here, we used allometry to estimate day ranges for those species that lacked empirical movement data and general additive models (GAM) to assess trends in density estimates. With this approach, we derived density estimates for 10 mammal species, regardless of whether they were abundant, or rare and elusive (e.g. carnivores). General additive models suggest that six species are stable or increasing, and four declining, although all nonsignificantly. Use of allometric estimates in lieu of empirical estimates led to falsely increased precision in density estimates, highlighting the need to fill the knowledge gap in movement ecology for certain species. Simulations were used to examine error introduced into trend estimates by this bias. We conclude that the FMP formula, when properly employed, can be an efficient method for simultaneous monitoring of multispecies in different functional groups. 相似文献
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我国东北地区的马鹿(Cervus elaphus)在内蒙古大兴安岭南麓的生态系统中占有重要位置,栖息地环境恶化以及人类活动干扰等因素严重影响了马鹿种群的生存状态。本文于2019至2020年采用样线法和粪堆计数法对内蒙古大兴安岭南麓野生马鹿种群恢复现状开展调查,估算其种群密度及数量。结果显示,与10年前相比,黄岗梁、白音敖包、大冷山、赛罕乌拉、乌兰坝和高格斯台的马鹿种群密度均有显著增长(P<0.05),研究区域现有马鹿总数量约为(9644.2±1378.6)头,种群密度(2.5±0.9)头/km^(2)。本次调查从种群密度、数量及增长率等方面探讨了进一步促进马鹿种群恢复的措施,为改进大兴安岭南麓马鹿保护工作提供科学指导。 相似文献
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Anthropogenic food from refuse tips can affect population dynamics in birds, especially gulls, but the evidence is mostly circumstantial. We combine analyses of long-term population data and natural experiments to show a positive effect of refuse tips on the growth of the Spanish breeding population of Rooks Corvus frugilegus . In this isolated population of around 2000 breeding pairs, monitored since 1976, birds in colonies less than 10 km from tips fed largely on refuse, particularly during periods of lowest natural food availability. Three lines of evidence support the hypothesis that the supply of refuse influenced breeding numbers, suggesting that this population is limited by food: 1) between 1976 and 2003, the two population nuclei that had access to tips increased 2.1 and 3.7 times more than that without a tip nearby; 2) annual colony growth between 1996 and 2003 was strongly correlated with the availability of tips when other potentially important variables were taken into account; 3) the number of breeding pairs in refuse-foraging colonies declined rapidly after the closure of the local tip and recovered only when a supply of refuse was restored. The effect of tips on colony growth was stronger when the availability of natural foraging habitat around the colonies was low, suggesting that anthropogenic food acts as a buffer against shortage of natural food. Artificial food supplementation may be an effective tool to increase the breeding population of target species, especially those facing a reduction of their foraging habitats. The potential effects on bird species of Directive 1999/31/CE, which is enforcing a massive closure of tips in Europe, are discussed. 相似文献
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Anthropogenic factors play an important role in shaping the distribution of wildlife species and their habitats, and understanding the influence of human activities on endangered species can be key to improving conservation efforts as well as the implementation of national strategies for sustainable development. Here, we used species distribution modeling to assess human impacts on the endangered red panda (Ailurus fulgens) in high‐altitude regions of Nepal. We found that the distance to paths (tracks used by people and animals), livestock density, human population density, and annual mean temperature were the most important factors determining the habitat suitability for red pandas in Nepal. This is the first study that attempts to use comprehensive environmental and anthropogenic variables to predict habitat suitability for the red pandas at a national level. The suitable habitat identified by this study is important and could serve as a baseline for the development of conservation strategies for the red panda in Nepal. 相似文献
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The use of light traps in sampling moth populations is an established technique used by entomologists and ecologists. However, trap data partly reflect the variable attractiveness of UV light to different species of moth. There are also potential problems of the practicality and expense of running traps in certain locations.An alternative method of recording moth populations is developed, using a modification of the transect count technique used for butterflies (Pollard and Yates, 1993) and recently applied to moths (Spalding, 1997). During transects, moths were observed by torch-light in a 5 by 5 m box, before the recorder walked on for 10 paces, and recorded moths in the next 5 m box. The transect approach was tested in the field, alongside traditional light trap and sugar methods.Transects recorded moth species for relatively little effort, produced repeatable measures of relative density, and provided habitat-specific data. This approach is likely to provide a valuable addition to light trapping in biodiversity inventories, species surveys, and in monitoring the effects of habitat management for conservation. 相似文献
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Georgia Thomson-Laing;Lena Schallenberg;David Kelly;Jamie D. Howarth;Susanna A. Wood; 《Biological reviews of the Cambridge Philosophical Society》2024,99(1):85-109
Freshwater fish are in a perilous state with more than 30% of species considered critically endangered. Yet significant ecological and methodological complexities constrain our ability to determine how disturbances are impacting native fish communities. We review current methods used to assess the responses of fish communities, especially native fish, to disturbances, with a focus on lakes. These methods include contemporary population surveys, manipulative experimental approaches, paleolimnological approaches and Indigenous Knowledge and social histories. We identify knowledge gaps, such as a lack of baseline data for native fish, an inability to assess the impact of historical disturbances, stressor response dynamics in contemporary multi-stressor environments, and natural disturbance regimes. Our assessment of the current methods highlights challenges to filling these knowledge gaps using the reviewed methods. We advocate strongly for the implementation of an integrative approach that combines emerging technologies (i.e. molecular-based techniques in contemporary surveys and paleolimnology) and underutilised knowledge streams (i.e. Indigenous Knowledge and social histories) which should be used in concert with conventional methods. This integrative approach will allow researchers to determine the key drivers of decline and the degree of change, which will enable more informed and successful management actions. 相似文献
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Luis M. Carrascal David Palomino Javier Seoane César L. Alonso 《African Journal of Ecology》2008,46(3):291-302
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M. P. GILLMAN M. E. DODD 《Botanical journal of the Linnean Society. Linnean Society of London》1998,126(1-2):65-74
Orchid population size has long been believed to be highly variable in time and space. Here we present the first quantitative assessment of the variability of orchid population sizes and compare them with plant and animal population data from the literature. Three measures of temporal variation were used (standard deviation of log10 (population size), Hurst exponent and variance in the intrinsic rate of increase). Eight unfertilized plots of Orchis morio in a factorial fertilizer experiment were assessed for variability in population size over a 26 year period. The Hurst exponent across the eight plots gave measures consistent with pink noise well into black noise (0.86 to 1.87). The variation in the intrinsic rate of increase suggested that the expected time to extinction in the plots differed by an order of magnitude. Standard deviation of log10 (population size) across plots was greater than the corresponding temporal variation within plots. Standard deviation of log10 (population size) reached an asymptote between 10 and 20 years. The range of temporal variation between plots in this and other orchid populations was as great as the mean values reported for birds, insects and mammals. These results have highlighted the importance of spatial variation: until we know the relative importance of spatial and temporal variation for more plant species we will be unable to assess whether orchid populations are more variable in size than other species. 相似文献
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ABSTRACT In accordance with federal regulations, the United States Fish and Wildlife Service developed a postdelisting monitoring plan for the bald eagle (Haliaeetus leucocephalus) designed to detect a change in the number of occupied nests on a national scale. The plan employs a dual-frame approach to the survey design where a list frame (list of known nests) and an area frame (set of survey plots) are used in concert to estimate the number of occupied nests in 5-year intervals over a 20-year period. The plan offers no provisions for changes in list-frame integrity, nor does it contemplate the impact of such changes on survey performance. We used a long-term data set to quantify occupancy patterns for nests in Virginia, USA, and evaluated their influence on integrity of the list frame and performance of the proposed dual-frame monitoring approach. The average annual turnover rate for nests was 0.261, resulting in a rapid decay of the list frame. Decay of the list frame leads to a functional collapse of the dual-frame approach, down to the area-frame survey alone, early within the monitoring time horizon. This early decay of the list frame implies that the area-frame coverage needed to maintain the same statistical power as stated in the monitoring plan would have to be increased by a factor of 3 to 5 beyond that recommended in the current plan. Remedies for this deficiency undermine the cost benefit associated with inclusion of the list frame. We examined response of the dual-frame survey to variation in nest turnover rates and population growth rates and defined a state space where time to collapse is beyond the proposed 20-year time horizon. Because, under realistic estimates of turnover rates, the dual-frame approach collapses to the area frame within the proposed monitoring window, we recommend that the costs of list-frame maintenance be included in the procedure to optimize allocation of survey effort. 相似文献
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Kathryn C. Grabenstein Ken A. Otter Theresa M. Burg Scott A. Taylor 《Global Change Biology》2023,29(4):955-968
Human habitat disturbances can promote hybridization between closely related, but typically reproductively isolated, species. We explored whether human habitat disturbances are related to hybridization between two closely related songbirds, black-capped and mountain chickadees, using both genomic and citizen science data sets. First, we genotyped 409 individuals from across both species' ranges using reduced-representation genome sequencing and compared measures of genetic admixture to a composite measure of human landscape disturbance. Then, using eBird observations, we compared human landscape disturbance values for sites where phenotypically diagnosed hybrids were observed to locations where either parental species was observed to determine whether hybrid chickadees are reported in more disturbed areas. We found that hybridization between black-capped and mountain chickadees positively correlates with human habitat disturbances. From genomic data, we found that (1) hybrid index (HI) significantly increased with habitat disturbance, (2) more hybrids were sampled in disturbed habitats, (3) mean HIs were higher in disturbed habitats versus wild habitats, and (4) hybrids were detected in habitats with significantly higher disturbance values than parentals. Using eBird data, we found that both hybrid and black-capped chickadees were significantly more disturbance-associated than mountain chickadees. Surprisingly, we found that nearly every black-capped chickadee we sampled contained some proportion of hybrid ancestry, while we detected very few mountain chickadee backcrosses. Our results highlight that hybridization between black-capped and mountain chickadees is widespread, but initial hybridization is rare (few F1s were detected). We conclude that human habitat disturbances can erode pre-zygotic reproductive barriers between chickadees and that post-zygotic isolation is incomplete. Understanding what becomes of recently hybridizing species following large-scale habitat disturbances is a new, but pressing, consideration for successfully preserving genetic biodiversity in a rapidly changing world. 相似文献
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ABSTRACT. Understanding variation in the detectability of birds is fundamental to determining the reliability of survey methods. We examined the influence of lunar light conditions on the detection probability of Whip-poor-wills through repeated sampling of 78 point count stations over two lunar cycles. The probability of detection was positively related to moonlight intensity measured as the percentage of moon-face illuminated and moon height above the horizon. These results were used to show how the reliability of long-term monitoring strategies can be improved by sampling design. Surveys conducted on nights when the moon-face was >50% illuminated were less variable and provided more statistical power to long-term monitoring results compared to surveys that were conducted across all nights. Stratifying surveys for Whip-poor-wills during bright moonlight provides greater statistical power for monitoring programs, which inevitably allows better scientific conclusions to be drawn from collected data. 相似文献
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近年黑龙江省凤凰山国家级自然保护区野猪数量不断增长,人猪冲突加剧,保护区资源保护管理工作面临较大管理压力.为确定野猪种群的实际数量,同时评估该保护区的野猪的容纳量水平,以便为保护区管理局针对野猪的管理提供相关指导意见.2009-2010年冬季,在保护区采用样带调查、雪地足迹链跟踪和观察食痕的方法,并结合已有野猪生态研究确定野猪食性.野猪主要食物种类包括:木贼(Equisetum hiemale)、红松(Pinus koraiensis)果实松籽、胡桃楸(Juglans mandshurica)果实核桃、蒙古栎(Quecusmongolica)果实橡子、稠李(Padus racemosa)、榛子(Corylus heterophlla)、苔草(Carex spp.)、辽东葱木(Aralia elata).研究期间共布设长3-5km、单侧宽度50m、总长134 km的样带30条.调查中,每隔200 m布设10 m×10 m的大样方,并在每个大样方中央及四角布设1 m×1 m的小样方,共布设大样方350个,小样方1 750个.通过样方调查,统计野猪栖息生境当年可食植物枝条及其食物种类,然后计算其食物的总供给量,再结合食物营养成分,通过粗蛋白、粗纤维、粗脂肪的能量转换,按照每克粗蛋白和粗纤维的能量转换系数为16.74kJ、每克粗脂肪的能量转换系数为37.66 kJ,确定野外生境食物总能量供给.结合野猪冬季日营养需求,以能量为基础估算保护区野猪的营养容纳量.在种群密度调查过程中,通过足迹链判断个体方法为:单一清晰足迹链确定为一个体所留,30m内多条足迹穿越同一样带被认为是一个野猪群所留,调查中根据个体分开时的足迹链数确定野猪个体数,同时将粪便、卧迹、啃食痕迹作为个体判断的辅助信息.研究结果表明:凤凰山保护区内能够提供的总能量为7.375 ×107MJ,冬季平均每头野猪生存所需能量为(14 677.698±409.92) MJ,野猪营养容纳量为(1 006±28)头,种群密度为(3.79±0.11)头/km2.此外,调查中发现30余个野猪套及2头野猪被猎杀现场,反应出当地的人猪冲突较为严重.结合调查中发现的野猪套数量及野猪被猎杀概率,对野猪种群数量引入20％的死亡风险系数.最终确定凤凰山野猪种群的最适数量在(603±17)头左右,最适密度为(2.27±0.06)头/km2.通过样带法调查得出凤凰山自然保护区实际野猪种群数量为(596±155)头,密度(2.24±0.58)头/km2,已趋近营养容纳量.因此,野猪并未过量,不能采取狩猎等降低种群数量的措施,同时保护区也应对野猪种群进行持续监控,防止野猪种群过度繁殖以至成灾. 相似文献
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植物吸收利用有机氮营养研究进展 总被引：4，自引：0，他引：4
植物矿质营养学问世以后,人们一直认为无机氮是植物吸收氮素的主要形态.随着研究手段的改进和研究内容的不断深入,现已证实许多没有菌根的维管植物都可以直接吸收可溶性有机氮,特别是小分子的氨基酸.由此引起了人们对植物有机营养、植物营养方式多样化问题的重视.研究表明：氨基酸可以通过多种方式释放到土壤溶液中,土壤中的氨基酸主要来源于微生物、动植物及其代谢产物等.土壤氨基酸含量受土壤温湿度、所施的有机肥料、生长的植物种类及其生长发育时期的影响.植物对氨基酸的吸收是一个主动吸收过程,受载体调节,并与能量状况有关,同时受介质中pH和温度的影响.但是有关植物吸收氨基酸的机理及其生态过程还需进行深入的研究. 相似文献