Five Potential Consequences of Climate Change for Invasive Species

Abstract:  Scientific and societal unknowns make it difficult to predict how global environmental changes such as climate change and biological invasions will affect ecological systems. In the long term, these changes may have interacting effects and compound the uncertainty associated with each individual driver. Nonetheless, invasive species are likely to respond in ways that should be qualitatively predictable, and some of these responses will be distinct from those of native counterparts. We used the stages of invasion known as the "invasion pathway" to identify 5 nonexclusive consequences of climate change for invasive species: (1) altered transport and introduction mechanisms, (2) establishment of new invasive species, (3) altered impact of existing invasive species, (4) altered distribution of existing invasive species, and (5) altered effectiveness of control strategies. We then used these consequences to identify testable hypotheses about the responses of invasive species to climate change and provide suggestions for invasive-species management plans. The 5 consequences also emphasize the need for enhanced environmental monitoring and expanded coordination among entities involved in invasive-species management.     

Global Warming and the Species Richness of Bats in Texas

General circulation models provide predictions for global climate under scenarios of increased atmospheric CO₂. Climate change is expected to lead directly to changes in distributions of vegetation associations. Distribution of animals will also change to the extent that animals rely on vegetation for food or shelter. Bat species in Texas appear to be restricted, in part, by the availability of roosts. We used geographic information systems and the Holdridge vegetation-climate association scheme to model the effect of climate change on bat distributions and species richness in Texas. Habitat characteristics for each species were identified from the literature and included vegetation, topography, and availability of caves. We assumed caves and topography to be fixed relative to climate. Vegetation changes were predicted from the Holdridge vegetation-climate association scheme. The redistribution of bats following climate change was predicted based on the new locations of suitable habitat characteristics. Under conditions of global warming tropical forests were predicted to expand into Texas; tree-roosting bats were sensitive to this change in vegetation. Cavity-roosting bats were less affected by changes in vegetation, but, where response was predicted, ranges decline.     

气候变化对物种影响研究综述

综述了气候变化对物种的影响,表明气候变化会造成生物物候期的改变,导致物种地理分布的变化,增加物种的灭绝速率。分析了利用模型进行气候变化影响模拟的技术,指出模型的适用性和不确定性。最后,针对中国相关研究的不足,展望了未来开展气候变化影响研究的方向。     

Assessing the Effects of Climate Change on Aquatic Invasive Species

Abstract:  Different components of global environmental change are typically studied and managed independently, although there is a growing recognition that multiple drivers often interact in complex and nonadditive ways. We present a conceptual framework and empirical review of the interactive effects of climate change and invasive species in freshwater ecosystems. Climate change is expected to result in warmer water temperatures, shorter duration of ice cover, altered streamflow patterns, increased salinization, and increased demand for water storage and conveyance structures. These changes will alter the pathways by which non-native species enter aquatic systems by expanding fish-culture facilities and water gardens to new areas and by facilitating the spread of species during floods. Climate change will influence the likelihood of new species becoming established by eliminating cold temperatures or winter hypoxia that currently prevent survival and by increasing the construction of reservoirs that serve as hotspots for invasive species. Climate change will modify the ecological impacts of invasive species by enhancing their competitive and predatory effects on native species and by increasing the virulence of some diseases. As a result of climate change, new prevention and control strategies such as barrier construction or removal efforts may be needed to control invasive species that currently have only moderate effects or that are limited by seasonally unfavorable conditions. Although most researchers focus on how climate change will increase the number and severity of invasions, some invasive coldwater species may be unable to persist under the new climate conditions. Our findings highlight the complex interactions between climate change and invasive species that will influence how aquatic ecosystems and their biota will respond to novel environmental conditions.     

对全球气候变化原因及发展趋势之浅见

分析了引起全球气候变化的各种可能原因，对温室气体、植被破坏、水汽变化等对全球气候变化的影响作了概括总结，阐述了全球气候变化发展趋势及气候变化预测中应注意的问题。     

A Successful Predictive Model of Species Richness Based on Indicator Species

Abstract:  Because complete species inventories are expensive and time-consuming, scientists and land managers seek techniques to alleviate logistic constraints on measuring species richness, especially over large spatial scales. We developed a method to identify indicators of species richness that is applicable to any taxonomic group or ecosystem. In an initial case study, we found that a model based on the occurrence of five indicator species explained 88% of the deviance of species richness of 56 butterflies in a mountain range in western North America. We validated model predictions and spatial transferability of the model using independent, newly collected data from another, nearby mountain range. Predicted and observed values of butterfly species richness were highly correlated with 93% of the observed values falling within the 95% credible intervals of the predictions. We used a Bayesian approach to update the initial model with both the model-building and model-validation data sets. In the updated model, the effectiveness of three of the five indicator species was similar, whereas the effectiveness of two species was reduced. The latter species had more erratic distributions in the validation data set than in the original model-building data set. This objective method for identifying indicators of species richness could substantially enhance our ability to conduct large-scale ecological assessments of any group of animals or plants in any geographic region and to make effective conservation decisions.     

Managing Aquatic Species of Conservation Concern in the Face of Climate Change and Invasive Species

Abstract:  The difficult task of managing species of conservation concern is likely to become even more challenging due to the interaction of climate change and invasive species. In addition to direct effects on habitat quality, climate change will foster the expansion of invasive species into new areas and magnify the effects of invasive species already present by altering competitive dominance, increasing predation rates, and enhancing the virulence of diseases. In some cases parapatric species may expand into new habitats and have detrimental effects that are similar to those of invading non-native species. The traditional strategy of isolating imperiled species in reserves may not be adequate if habitat conditions change beyond historic ranges or in ways that favor invasive species. The consequences of climate change will require a more active management paradigm that includes implementing habitat improvements that reduce the effects of climate change and creating migration barriers that prevent an influx of invasive species. Other management actions that should be considered include providing dispersal corridors that allow species to track environmental changes, translocating species to newly suitable habitats where migration is not possible, and developing action plans for the early detection and eradication of new invasive species.     

Current Practices and Future Opportunities for Policy on Climate Change and Invasive Species

Abstract:  Climate change and invasive species are often treated as important, but independent, issues. Nevertheless, they have strong connections: changes in climate and societal responses to climate change may exacerbate the impacts of invasive species, whereas invasive species may affect the magnitude, rate, and impact of climate change. We argue that the design and implementation of climate-change policy in the United States should specifically consider the implications for invasive species; conversely, invasive-species policy should address consequences for climate change. The development of such policies should be based on (1) characterization of interactions between invasive species and climate change, (2) identification of areas where climate-change policies could negatively affect invasive-species management, and (3) identification of areas where policies could benefit from synergies between climate change and invasive-species management.     

物种丰富度格局研究进展

阐明了物种丰富度格局变化及其环境影响因子,并论述了目前研究较多的能量假说、地质历史过程假说、中域效应假说和Rapoport法则4种假说。这些假说对物种丰富度格局成因作出了一定解释,但针对不同的地理区域,其普适性尚需进一步研究。此外,对物种丰富度格局研究中常用的技术方法和影响格局分布的因素加以归纳总结,对我国未来物种丰富度格局研究进行展望,为制定区域生物物种资源保护战略提供参考。     

The Use of Species Accumulation Functions for the Prediction of Species Richness

We develop a stochastic theory of the accumulation of new species in faunistic or floristic inventories. Differential equations for the expected list size and its variance as a function of the time spent collecting are presented and solved for particular cases. These particular cases correspond to different models of how the probability of adding a new species changes with time, the size of the list, the complexity of the area sampled, and other parameters. Examples using field data from butterflies and mammals are discussed, and it is argued that the equations relating sampling effort with size of the list may be useful for conservation purposes because they should lend formality to comparisons among lists and because they may have predictive power by extrapolating the asymptotic size of the lists. The suitability of different models to a variety of field situations is also discussed.     

Capacity of Management Plans for Aquatic Invasive Species to Integrate Climate Change

Abstract:  The consequences of climate change will affect aquatic ecosystems, including aquatic invasive species (AIS) that are already affecting these ecosystems. Effects on AIS include range shifts and more frequent overwintering of species. These effects may create new challenges for AIS management. We examined available U.S. state AIS management plans to assess each program's capacity to adapt to climate-change effects. We scored the adaptive capacity of AIS management plans on the basis of whether they addressed potential impacts resulting from climate change; demonstrated a capacity to adapt to changing conditions; provided for monitoring strategies; provided for plan revisions; and described funding for implementation. Most plans did not mention climate change specifically, but some did acknowledge climatic boundaries of species and ecosystem sensitivities to changing conditions. Just under half the plans mentioned changing environmental conditions as a factor, most frequently as part of research activities. Activities associated with monitoring showed the highest capacity to include information on changing conditions, and future revisions to management plans are likely to be the easiest avenue through which to address climate-change effects on AIS management activities. Our results show that programs have the capacity to incorporate information about climate-change effects and that the adaptive-management framework may be an appropriate approach.     

Scale-Dependent Effects of Habitat Disturbance on Species Richness in Tropical Forests

Abstract: Despite growing concern, no consensus has emerged over the effects of habitat modification on species diversity in tropical forests. Even for comparatively well-studied taxa such as Lepidoptera, disturbance has been reported to increase and decrease diversity with approximately equal frequency. Species diversity within landscapes depends on the spatial scale at which communities are sampled, and the effects of disturbance in tropical forests have been studied at a wide range of spatial scales. Yet the question of how disturbance affects diversity at different spatial scales has not been addressed. We reanalyzed data from previous studies to examine the relationship between spatial scale and effects of disturbance on tropical-forest Lepidoptera. Disturbance had opposite effects on diversity at large and small scales: as scale decreased, the probability of a positive effect of disturbance on diversity increased. We also explicitly examined the relationship between spatial scale and the diversity of butterflies in selectively logged and unlogged forest in Maluku Province, Indonesia. Species richness increased with spatial scale in both logged and unlogged forest, but at a significantly faster rate in unlogged forest, whereas species evenness increased with scale in unlogged forest but did not increase with scale in logged forest. These data indicate that the effects of habitat modification on species diversity are heavily scale-dependent. As a result, recorded effects of disturbance were strongly influenced by the spatial scale at which species assemblages were sampled. Future studies need to account for this by explicitly examining the effects of disturbance at a number of different spatial scales. A further problem arises because the relationship between scale and diversity is likely to differ among taxa in relation to mobility. This may explain to some extent why the measured effects of disturbance have differed between relatively mobile and immobile taxa.     

Effects of Climate and Land-Use Change on Species Abundance in a Central European Bird Community

Abstract:  Although it is known that changes in land use and climate have an impact on ecological communities, it is unclear which of these factors is currently most important. We sought to determine the influence of land-use and climate alteration on changes in the abundance of Central European birds. We examined the impact of these factors by contrasting abundance changes of birds of different breeding habitat, latitudinal distribution, and migratory behavior. We examined data from the semiquantitative Breeding Bird Atlas of Lake Constance, which borders Germany, Switzerland, and Austria. Changes in the regional abundance of the 159 coexisting bird species from 1980–1981 to 2000–2002 were influenced by all three factors. Farmland birds, species with northerly ranges, and long-distance migrants declined, and wetland birds and species with southerly ranges increased in abundance. A separate analysis of the two decades between 1980–1981 and 1990–1992 and between 1990–1992 and 2000–2002 showed that the impact of climate change increased significantly over time. Latitudinal distribution was not significant in the first decade and became the most significant predictor of abundance changes in the second decade. Although the spatial scale and temporal resolution of our study is limited, this is the first study that suggests that climate change has overtaken land-use modification in determining population trends of Central European birds.     

气候变化对我国丹顶鹤繁殖地分布的影响

利用最大熵模型,结合大气环流模型和IPCC(政府间气候变化专门委员会)最新发布的A2和B2气候情景,模拟和预测气候变化对我国东北地区丹顶鹤(Grus japonensis)繁殖地分布范围及空间格局的影响趋势。结果表明,在A2和B2气候情景下,气候变化将导致丹顶鹤的繁殖适生区域不断缩减,核心分布区域向西和向北移动,其中东北3省的栖息地变化明显,内蒙古东部地区未来将成为丹顶鹤的主要栖息地。认为我国急需建立一套完整可靠的丹顶鹤分布监测系统,进一步加强湿地的人工补水和湿地恢复等工作,以利于丹顶鹤繁殖地的保护。     

Species Migrations and Ecosystem Stability During Climate Change: The Belowground Connection

Abstract: Compatibility between the belowground mutualists of resident species and the needs of immigrant species will strongly influence the successful transition from one perennial plant community to another during climate change. A hiatus in the overlap between plant species that maintain a positive link with the soil ecosystem could result in site capture by weeds and rapid degradation of the productive capacity of soils. We discuss instances in which such rapid degradation has occurred and argue for the crucial importance of protecting plant-soil links in the coming decades through maintaining biodiversity and utilizing management practices that help plants keep a firm grip on the soil. Examples of the latter include partial and dispersed cutting in forestry, use of green cover crops in agriculture and grazing intensities that permit degraded range to rebuild.