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Cameron W. Barrows Kathleen D. Fleming Michael F. Allen 《The Journal of wildlife management》2011,75(3):682-691
Anthropogenic habitat fragmentation typically precedes conservation planning; maintaining remaining linkages among core habitat areas can thus become a key conservation objective. Identifying linkages for dispersal and ensuring those linkages have long-term protection and management are challenging tasks for wildlife managers. These tasks can be especially daunting for smaller species with low mobility, termed corridor dwellers, which must maintain sustainable populations within corridors. Between May 2007 and June 2009, we collected occurrence locations for a corridor dweller, the Palm Springs pocket mouse (Perognathus longimembris bangsii), from museums, previous research, and our own field sampling. We used those data to model their suitable niche space and then identify suitable linkages between proposed conservation areas. We used a partitioned Mahalanobis D2 statistic to create a spatially explicit niche model describing the distribution of a suitable niche space, and we validated the model statistically, with live trapping and with burrowing owl (Athene cunnicularia) diets. Our model identified soil characteristics, topographic ruggedness, and vegetation as variables delimiting Palm Springs pocket mouse habitat; sand content of the soils was an especially important characteristic. Our historic distribution model identified 120,000–90,000 ha as historically potential Palm Springs pocket mouse habitat; roughly 39% of that has been lost to more recent development. Most of the remaining suitable habitat occurred in the northwestern portion of the valley. We modeled habitat within core reserves as well as within proposed linkages between those reserves as having high similarity to known occupied habitats. Live trapping in areas with high (≥0.95) Habitat Suitability Index (HSI) values resulted in captures at 66% of those locations and, along with burrowing owl diets, refined a qualitative model as to what constituted a suitable Palm Springs pocket mouse corridor. While most corridor analyses have focused on mobile species which may traverse corridors in hours, days, or weeks, linkages for corridor dwellers must include habitat for sustaining multi-generational populations. This requires evaluating whether continuous suitable habitat exists within proposed corridors. Our research demonstrates how niche modeling can provide a landscape-scale view of the distribution of suitable habitat to evaluate conservation objectives for connectivity. © 2011 The Wildlife Society. 相似文献
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Invasion and expansion of non-native and native plants have altered vegetation structure in many terrestrial ecosystems. Small mammals influence multiple ecosystem processes through their roles as ecosystem engineers, predators, and prey, and changes to vegetation structure can affect habitat use, community composition, and predator-prey interactions for this assemblage of wildlife. In the sagebrush (Artemisia spp.) shrublands of the western United States, invasion by non-native grasses and expansion of native conifer trees beyond their historical range has altered vegetation structure. These changes may potentially affect distributions and interactions of deer mice (Peromyscus maniculatus), which are generalist omnivores, and Columbia Plateau pocket mice (Perognathus parvus), more specialized granivores. To assess the extent to which altered habitat affects small-mammal density, survival, and home-range size, we examined these aspects of small-mammal ecology along a gradient of cheatgrass (Bromus tectorum) invasion and western juniper (Juniperus occidentalis) establishment in sagebrush shrublands in southwestern Idaho, USA. From 2017–2019, we used a spatially explicit mark-recapture design to examine attributes of small-mammal ecology along an invasion gradient. We did not find support for an effect of cheatgrass cover on density or survival of either species. Home-range size of deer mice was 2.3 times smaller in heavier cheatgrass cover (60%) compared to areas with little or no cheatgrass cover. Density of deer mice was highest (5 individuals/ha) in areas with 10% juniper cover and decreased with increasing juniper cover, whereas density of pocket mice was positively influenced by shrub cover. Survival of deer mice declined as juniper stem density increased. Conversely, survival of pocket mice increased with increasing juniper stem density. We found evidence for interspecific interactions between these 2 species, in the form of a density-dependent effect of deer mice on pocket mouse home-range size. Home-range size for pocket mice was 2 times smaller in areas with the highest estimated density of deer mice compared to areas with low densities of deer mice. Our data provides unique information about how small mammals in the sagebrush steppe are affected by expanding and invasive plant species and potential ways that habitat restoration efforts, in the form of conifer removal, may influence small mammals. Understanding the response of small mammals to conifer expansion or removal may shed light on the demographic and numerical responses of other wildlife associated with the sagebrush biome, including predators. 相似文献
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Xiaoping He Aimee Lee S. Houde Bryan D. Neff Daniel D. Heath 《Ecology and evolution》2018,8(3):1769-1777
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- Cane toads (Rhinella marina) have wrought considerable ecological damage during their invasion of tropical Australia, spurring the search for novel ways to reduce toad numbers.
- Previous laboratory and field studies have shown that the tadpoles of native frogs, which often co‐occur with toad tadpoles in temporary waterbodies, compete with the invaders and can suppress their survival, growth and development.
- Understanding the mechanisms responsible for that competitive suppression might suggest new ways to control toads: for example, a chemical produced by native tadpoles that disrupts toad development.
- Our laboratory experiments confirm that toad tadpoles are negatively affected by the presence of tadpoles of three native hylid frogs (Litoria caerulea, Litoria longipes and Litoria splendida) and identify direct exploitative competition for food as the primary mechanism. Manipulations of chemical cues and visual cues in the water had no significant effects on the viability of toads, whereas manipulations of direct physical contact and food supply relative to tadpole density had strong effects.
- The lack of chemically mediated interference competition may reflect the very short timescale of sympatry between the invader and native taxa, restricting opportunities for the evolution of such mechanisms.
- Re‐introducing native anurans to anthropogenically degraded sites (especially those where local frogs previously occurred, but have been lost) may provide a simple and effective way to reduce the recruitment rate of invasive cane toads.
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Human disturbance and climate change have increased the risk of extinction for rare and endangered wild plant species.One effective way to conserve these rare and endangered species is through reintroduction.In this review,we summarize the advances in wild plant reintroduction from five perspectives:the establishment of reintroduction biology as an important tool for biodiversity conservation;the importance of genetic diversity in reintroduction;reintroduction under global climate change;recruitment limitation in reintroduction;and reintroduction and ecological restoration.In addition,we consider the future of plant reintroduction strategies. 相似文献
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采用改进的竞争指数模型研究安徽天柱山黄山松的种内和种间竞争强度。结果发现:(1)随对象木胸径的增大,黄山松种群因自然稀疏过程中密度调节作用,植株距离增加,种内竞争强度降低;(2)黄山松群落内其它物种虽然较多,但个体普遍较小,结果种间竞争相对较弱,种内与种间竞争关系顺序为:黄山松—黄山松>杉木—黄山松>枹栎—黄山松>其它树种—黄山松;(3)竞争强度和对象木胸径的关系服从幂函数关系(CI=AD-B),当黄山松胸径达到20cm以上时,竞争强度变化不大,所得的预测模型能很好地预测黄山松种内和种间的竞争强度;(4)改进的竞争指数模型能很好地度量黄山松的种内和种间竞争强度,改进的确定邻体范围的方法能有效地确定黄山松的竞争范围。 相似文献
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竞争是植物种内和种间关系的主要形式之一。通过对黑龙江穆棱东北红豆杉自然保护区的95株东北红豆杉对象木及980株竞争木的调查,运用Hegyi的单木竞争指数计算分析了东北红豆杉的种内和种间竞争强度。东北红豆杉的种内竞争强度不大,占总竞争的4%。竞争压力更多的来自于种间竞争,占总竞争的96%。与东北红豆杉竞争激烈的树种主要是冷杉、紫椴、色木槭和红松等地带性植被的优势种。随着东北红豆杉胸径的增大,所受到的竞争压力逐渐减小,胸径在20cm以前所受到的竞争压力最大,竞争强度与对象木胸径符合幂函数（CI=AD^-B）关系。 相似文献
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山西稀有濒危植物脱皮榆种内和种间竞争 总被引：2，自引：0，他引：2
通过对山西太岳山一块100 m×100 m样地中128株脱皮榆对象木及1093株竞争木的调查,运用Hegyi的单木竞争指数计算分析了脱皮榆的种内和种间竞争强度。结果表明:(1)脱皮榆种群所受到的竞争强度随着对象木胸径的增大而逐渐减小;(2)调查样地内尽管其他物种种类较多,但数量较少,与脱皮榆种间竞争相对较弱,脱皮榆种内与种间竞争关系的顺序为:脱皮榆-脱皮榆>千金榆-脱皮榆>五角枫-脱皮榆>茶条槭-脱皮榆>其他树种-脱皮榆;(3)竞争强度和对象木胸径的关系服从幂函数关系,当脱皮榆胸径在25 cm以上时,竞争强度变化不大,所得的预测模型能很好地预测脱皮榆种内种间竞争强度。 相似文献
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The diets of two urolophids, the common stingaree Trygonoptera testacea and the kapala stingaree Urolophus kapalensis were analysed and compared to examine resource partitioning between these two morphologically similar sympatric Australian batoids. The diet of T. testacea was polychaete-based, while that of U. kapalensis was dominated by crustaceans (mostly carid shrimps and amphipods). Intraspecific dietary compositions were examined amongst size classes within each of the two species to identify ontogenetic shifts in diet. Differences in the dietary compositions of the smaller total-length classes of T. testacea suggest that their diet shifts as they increase in size, from one dominated by carids to one almost entirely comprising polychaetes. Significant ontogenetic dietary shifts were not identified in U. kapalensis . Although the two species shared eight broad dietary categories, their overall dietary compositions were found to be significantly different. The limited overlap in the dietary compositions of these two sympatric stingarees suggests the possibility of resource partitioning, with interspecific competition being implicated as a possible cue. Possible mechanisms for the partitioning of resources within and between these two species are discussed. 相似文献
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Food-storing birds lose a great deal of their stored food toother animals. We examined whether blackcapped chickadees (Parusairicapillus) modify their choice of cache sites using informationthat predicts cache loss. In experiment 1, birds learned toavoid caching at spatial locations where cache loss had previouslyoccurred, but they did not avoid caching near local color cuesthat predicted cache loss. Birds did not modify their generaluse of space in the aviary. Birds also learned to reduce searchingfor caches where spatial location predicted cache loss. Experiment2 confirmed the birds’ ability to discriminate among thespatial locations and the local color cues used in experiment1. In experiment 3, learning a food-rewarded approach to potentialcache sites occurred without any change in the choice of sitesfor caching. We discuss how chickadees selectively associatethe choice of cache site with its consequences, even over delaysof several hours between caching and cache recovery. 相似文献
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蒙古栎(Quercus mongolica Fischer ex Ledebour)林是东北地区常见的典型森林类型之一。以黑龙江中央站黑嘴松鸡国家级自然保护区面积为1 hm 2的蒙古栎林固定样地为研究对象,采用固定样圆法确定了竞争范围,并利用Hegyi竞争指数分析了蒙古栎林的种内和种间竞争状态。研究结果表明:蒙古栎的种内和种间竞争强度分别占总竞争强度的28.08%和71.92%,说明了蒙古栎的种内竞争强度小,竞争压力主要来自于种间。白桦(Betula platyphylla Suk.)、黑桦(Betula dahurica Pall.)、兴安落叶松(Larix gmelinii(Ruprecht)Kuzeneva)数量较多,个体高大,对蒙古栎的竞争压力较大。蒙古栎种内和种间竞争强度的顺序为:白桦>蒙古栎>黑桦>兴安落叶松>山杨(Populus davidiana Dode)>紫椴(Tilia amurensis Rupr.)>大黄柳(Salix raddeana Laksch.)。蒙古栎的胸径与整个林分、伴生树种以及蒙古栎种内的竞争强度成幂函数关系,随着对象木胸径增大,3种竞争强度均减小。当蒙古栎胸径小于20 cm时,竞争强度较大;当胸径大于20 cm时,蒙古栎所受的竞争压力较小,并趋于稳定,通过所得的模型可以很好地预测出蒙古栎种内和种间的竞争强度。 相似文献
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通过对安徽省岳西县大别山五针松群落内的53株对象木及2079株竞争木的调查,运用Hegyi单木竞争模型分析了大别山五针松的种内和种间竞争强度。结果表明,大别山五针松的种内和种间竞争强度分别为17.11%和82.89%,说明竞争主要来自种间。大别山五针松的伴生种较多,种内与主要伴生种间的竞争关系为短柄枹大别山五针松种内黄山松满山红茅栗金缕梅紫茎四照花灯台树鹅耳枥。竞争强度随对象木胸径的增大而减小,当对象木的胸径小于25cm时,所受到的竞争强度较大;当胸径在25cm以上时,竞争强度变化很小,二者符合幂函数关系(CI=AD-B),所得的预测模型能很好的预测大别山五针松种内和种间竞争强度。 相似文献
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濒危植物宝华玉兰种内与种间竞争 总被引：5，自引：2，他引：5
利用Hegyi单木竞争指数模型对江苏镇江宝华山国家森林公园特有濒危植物宝华玉兰种内、种间竞争强度进行定量分析。结果表明:宝华玉兰竞争压力主要来自种间,占总竞争的90.7%。宝华玉兰种内竞争、种间竞争强度大小顺序为:紫楠>野核桃>建始槭>宝华玉兰种内>毛竹>化香>枫香>皂荚>朴树。整个林分竞争木对对象木的竞争强度与对象木的胸径大小近似服从幂函数关系,而伴生树种竞争木对对象木的竞争强度与对象木的胸径大小近似服从对数函数关系。种间竞争强度和对象木的胸径大小呈显著负相关。利用模型预测,当宝华玉兰的胸径达到30cm后,竞争强度几乎没有变化。研究认为,将无性系分株换算为一株与其胸高断面积之和相等的个体更为合理。 相似文献
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Large carrion is inhabited by highly variable and interactive communities of insects. Positive interactions in carrion insect communities have been recently the focus in carrion ecology. In contrast, competition between carrion insects is rather undervalued. Here we provide evidence that blow flies (Calliphoridae) and Necrodes beetles (Silphidae), dominant decomposers of large carcasses in terrestrial habitats, compete over carrion. By reanalyzing the results from 90 pig carcasses, we demonstrated that the contribution of the flies and the beetles to the decay was negatively related. The greater part of the large carrion pool was monopolized by blow flies, whereas Necrodes beetles abundantly colonized carcasses, on which blow flies were less effective as decomposers. In behavioral assays, we found that adult beetles killed 4 times more frequently feeding than postfeeding third instar larvae of the flies, with the large decrease in the killing frequency after the larvae reached the age of early third instar. Therefore, adult Necrodes beetles preferentially killed the larvae that were before or in their peak feeding. The study provides evidence that the interaction between blow flies and Necrodes beetles is a combination of indirect exploitative effects of the flies and direct interference effects of the beetles (the mixed competition). 相似文献
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利用Hegyi的单木竞争指数模型对黄土高原马栏林区辽东栎(Quercus liaotungensis)的种内和种间竞争强度进行了定量分析.结果显示:(1)辽东栎种内竞争强度与种间竞争强度的总和大致相等,其种内及种间竞争强度均随对象木胸径的增大而逐渐减小,其关系服从幂函数规律,竞争主要发生在胸径小于15 cm的幼树阶段.(2)各组成树种对辽东栎影响程度(竞争指数)的大小顺序为:辽东栎>油松(Pinus tabulaeformis)>白桦(Betulaplatyphylla)>山杨(Populus davidiana)>杜梨(Pyrus betulaefolia)>湖北山楂(Crataegus hupehensis)>茶条槭(Acer ginnala)>陕西鹅耳枥(Carpinus shensiensis)>葛萝槭(A.grosseri).(3)油松是该地区的次优势种,对辽东栎有较大的竞争压力,在群落发展中可能会形成以油松占优势的混交林.(4)辽东栎胸径小于15 cm时,种内种间竞争是导致大量个体死亡的主要原因;胸径超过15 cm时,人为砍伐可能是个体死亡的主要原因.研究结果认为马栏林区混交林油松的密度不宜过大,尤其是在与未成熟辽东栎种群混交时密度应合理,应对该林区的混交林进行人工抚育,及时择伐密度过大的油松,而在辽东栎胸径达到15 cm之前择伐长势较差的植株,以促使森林群落尽快趋于稳定. 相似文献
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William P. Brown 《Journal of Biogeography》2007,34(12):2168-2181
Aim Many theories of biodiversity and biogeography assume that species respond equally to variability in habitat area and isolation. This assumption does not allow for differential responses due to interspecific competition or other mechanisms, and therefore does not allow community composition to be predicted. As body size is relevant to area requirements and interspecific dominance, a natural experiment was conducted to quantify the differential responses of avian species abundance to variability in remnant area, isolation and forest cover based on average species body mass. Location Deciduous forest remnants of varying area and isolation throughout the State of Delaware, USA. Methods Forest remnants within stratified area and isolation classes were randomly selected for breeding bird surveys; total forest cover (ha) within 2 km of each survey point was subsequently determined as a covariate. Surveys were conducted within 100–150 m from the edge of each remnant and detected bird species were divided into five classes based on a log2‐transformation of body mass (very small, small, medium, large and very large). Assuming a negative binomial distribution, the abundance of detected individuals in each mass class was analysed using generalized linear models with remnant area, isolation, local forest cover and two‐way interactions specified as independent variables. The same analyses were conducted for individual species where sample size allowed. Results Very small, small and very large bodied species decreased in abundance with decreasing local forest cover and remnant area and with increasing remnant isolation, while large species increased in abundance. Medium‐sized species decreased in abundance with increasing forest cover, did not respond to remnant isolation and showed a concave, curvilinear response to increasing remnant area. Large and medium‐sized species were the most abundant birds in small, isolated remnants despite occurring in the largest remnants with the more abundant very small and small species, suggesting that communities are not randomly organized. Main conclusions Regardless of presumed habitat associations, large and medium‐sized species are of the appropriate size to be dominant competitors when forest resources are limiting, and thus may be considered ‘generalists’. The smallest species may be excluded entirely from small, isolated remnants even though such remnants meet their ecological needs; the needs of very large species are not met in small remnants. The applicability of biodiversity theories to community composition, species abundance and, by extension, to conservation, can be improved by incorporating differential responses based on body mass into their assumptions. 相似文献
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