Assisted migration of plants: Changes in latitudes, changes in attitudes

Rapid climate change has the potential to alter the location of bioclimatic envelopes for a significant portion of the world’s flora. Plant species will respond variously via phenotypic plasticity, evolutionary adaptation, migration, or extinction. When fragmentation limits migration potential of many species or when natural migration rates are outstripped by the pace of climate change, some propose purposeful, human-mediated migration (assisted migration) as a solution. Here, we join the debate on assisted migration, and while recognizing the potential negative impacts, present a strategy to collect and bank seeds of plant species at risk of extinction in the face of rapid climate change to ensure that emerging habitats are as species-diverse as possible. We outline the framework currently being used by the Dixon National Tallgrass Prairie Seed Bank to prioritize species for seed banking, both for restoration purposes and for potential assisted migration in the future. We propose a strategy for collecting across the entirety of a species range, while targeting populations likely to go extinct under climate change, determined by application of species distribution models. Finally, we discuss current international efforts to collect and bank the global flora, as well as the research needs necessary to fully undertake the strategy presented.     

Ecological and anthropomorphic factors permitting low-risk assisted colonization in temperate grassy woodlands

There is a risk that the potential of assisted colonization to contribute to biodiversity conservation will be lost in the storm of controversy that currently surrounds it. This paper describes a low-risk scenario for assisted colonization using plants. Using an analysis of temperate grassy woodlands from Australia, relevant ecosystem attributes are identified which make assisted colonization a sensible strategy, and that may characterize other favorable situations globally. The contributing elements include: a biota adapted to resource conservatism, a naturally connected landscape with component species having wide distributions over a large climatic gradient, current land use unrelated to endogenous disturbance regimes resulting in extensive replacement and modification of the ecosystem over its entire range. Intensive agriculture can create a highly-disturbed and nutrient-enriched landscape matrix, which effectively fragments the species assemblage. Relocation of plant species within and close to their range is not going to create an invasive situation in these landscapes. Candidates for assisted colonization are forbs and interstitial grasses that have persisted over much of their range, but which have declined within that range due to land use impacts. The suggested priority receiving sites would be those with a moderate level of past modifications, now being managed for conservation and with low nutrient status. The proposed use of assisted colonization is a conservative strategy that will build on current conservation practice and greatly improve the prospects for native plants where climate change is superimposed on a fragmented plant community.     

Conservation and climate change: Assessing the vulnerability of snow leopard habitat to treeline shift in the Himalaya

Climate change is likely to affect the persistence of large, space-requiring species through habitat shifts, loss, and fragmentation. Anthropogenic land and resource use changes related to climate change can also impact the survival of wildlife. Thus, climate change has to be integrated into biodiversity conservation plans. We developed a hybrid approach to climate-adaptive conservation landscape planning for snow leopards in the Himalayan Mountains. We first mapped current snow leopard habitat using a mechanistic approach that incorporated field-based data, and then combined it with a climate impact model using a correlative approach. For the latter, we used statistical methods to test hypotheses about climatic drivers of treeline in the Himalaya and its potential response to climate change under three IPCC greenhouse gas emissions scenarios. We then assessed how change in treeline might affect the distribution of snow leopard habitat. Results indicate that about 30% of snow leopard habitat in the Himalaya may be lost due to a shifting treeline and consequent shrinking of the alpine zone, mostly along the southern edge of the range and in river valleys. But, a considerable amount of snow leopard habitat and linkages are likely to remain resilient to climate change, and these should be secured. This is because, as the area of snow leopard habitat fragments and shrinks, threats such as livestock grazing, retaliatory killing, and medicinal plant collection can intensify. We propose this approach for landscape conservation planning for other species with extensive spatial requirements that can also be umbrella species for overall biodiversity.     

Future habitat loss and the conservation of plant biodiversity

Rapid land-use and climate changes are projected to cause broad-scale global land-cover transformation that will increase species extinction rates. We assessed the exposure of globally threatened plant biodiversity to future habitat loss over the first half of this century by testing country-level associations between threatened plant species richness and future habitat loss owing to land-use and climate changes, separately. In countries overlapping Biodiversity Hotspots, plant species endangerment increases with climate change-driven habitat loss. This association suggests that many currently threatened plant species will become extinct owing to anthropogenic climate change in the absence of potentially mitigating factors such as natural and assisted range shift, and physiological and genetic adaptations. Countries rich in threatened species, which are also projected to have relatively high total future habitat loss, are concentrated around the equator. Because poverty and poor governance can compromise conservation, we considered the economic condition and quality of governance with the degree of plant species endangerment and future habitat loss to prioritize countries based on conservation need. We identified Angola, Cuba, Democratic Republic of Congo, Ethiopia, Kenya, Laos, Madagascar, Myanmar, Nepal, Tajikistan, and Tanzania as the countries in greatest need of conservation assistance. For conservation endeavors to be effective, the conservation capacity of these high-need countries needs to be improved by assisting political stability and economic sustainability. We make policy recommendations that aim to mitigate climate change, promote plant species conservation, and improve the economic conditions and quality of governance in countries with high conservation need.     

Regional climate change adaptation strategies for biodiversity conservation in a midcontinental region of North America

Scenario planning should be an effective tool for developing responses to climate change but will depend on ecological assessments of broad enough scope to support decision-making. Using climate projections from an ensemble of 16 models, we conducted an assessment of a midcontinental area of North America (Minnesota) based on a resistance, resilience, and facilitation framework. We assessed likely impacts and proposed options for eight landscape regions within the planning area. Climate change projections suggest that by 2069, average annual temperatures will increase 3 °C with a slight increase in precipitation (6%). Analogous climate locales currently prevail 400–500 km SSW. Although the effects of climate change may be resisted through intensive management of invasive species, herbivores, and disturbance regimes, conservation practices need to shift to facilitation and resilience. Key resilience actions include providing buffers for small reserves, expanding reserves that lack adequate environmental heterogeneity, prioritizing protection of likely climate refuges, and managing forests for multi-species and multi-aged stands. Modifying restoration practices to rely on seeding (not plants), enlarge seed zones, and include common species from nearby southerly or drier locales is a logical low-risk facilitation strategy. Monitoring “trailing edge” populations of rare species should be a high conservation priority to support decision-making related to assisted colonization. Ecological assessments that consider resistance, resilience, and facilitation actions during scenario planning is a productive first step towards effective climate change planning for biodiversity with broad applicability to many regions of the world.     

Adapting global conservation strategies to climate change at the European scale: The otter as a flagship species

Climate change has created the need for new strategies in conservation planning that account for the dynamics of factors threatening endangered species.Here we assessed climate change threat to the European otter, a flagship species for freshwater ecosystems, considering how current conservation areas will perform in preserving the species in a climatically changed future. We used an ensemble forecasting approach considering six modelling techniques applied to eleven subsets of otter occurrences across Europe. We performed a pseudo-independent and an internal evaluation of predictions. Future projections of species distribution were made considering the A2 and B2 scenarios for 2080 across three climate models: CCCMA-CGCM2, CSIRO-MK2 and HCCPR HADCM3. The current and the predicted otter distributions were used to identify priority areas for the conservation of the species, and overlapped to existing network of protected areas.Our projections show that climate change may profoundly reshuffle the otter’s potential distribution in Europe, with important differences between the two scenarios we considered. Overall, the priority areas for conservation of the otter in Europe appear to be unevenly covered by the existing network of protected areas, with the current conservation efforts being insufficient in most cases. For a better conservation, the existing protected areas should be integrated within a more general conservation and management strategy incorporating climate change projections. Due to the important role that the otter plays for freshwater habitats, our study further highlights the potential sensitivity of freshwater habitats in Europe to climate change.     

Taking stock of the assisted migration debate

Assisted migration was proposed several decades ago as a means of addressing the impacts of climate change on species populations. While its risks and benefits have been debated, and suggestions for planning and management given, there is little consensus within the academic literature over whether to adopt it as a policy. We evaluated the main features of the assisted migration literature including the study methods, taxonomic groups, geographic regions and disciplines involved. We further assessed the debate about the use of assisted migration, the main barriers to consensus, and the range of recommendations put forth in the literature for policy, planning or implementation. Commentaries and secondary literature reviews were as prevalent as first-hand scientific research and attention focussed on a global rather than regional level. There was little evidence of knowledge transfer outside of the natural sciences, despite the obvious policy relevance. Scholarly debate on this topic has intensified during the last 3 years. We present a conceptual framework for evaluating arguments in the debate, distinguishing among the direct risks and benefits to species, ecosystems and society on the one hand, and other arguments regarding scientific justification, evidence-base and feasibility on the other. We also identify recommendations with potential to advance the debate, including careful evaluation of risks, benefits and trade-offs, involvement of relevant stakeholders and consideration of the complementarity among assisted migration and less risk-tolerant strategies. We conclude, however, that none of these will solve the fundamental, often values-based, challenges in the debate. Solutions are likely to be complex, context-dependent and multi-faceted, emerging from further research, discussion and experience.     

Climate change and translocations: The potential to re-establish two regionally-extinct butterfly species in Britain

Climate change is causing many organisms to migrate to track climatically-suitable habitat. In many cases, this will happen naturally, but in others, human intervention may be necessary in the form of ‘assisted colonisation’. Species re-establishments in suitable parts of their historic ranges provide an opportunity to conserve some species and to test ideas about assisted colonisation. Here, bioclimatic models of the distributions of two extinct British butterflies, Aporia crataegi and Polyommatus semiargus, were used to investigate the potential for re-establishment in Britain. Generalised additive models and generalised linear models were created to describe the species’ European distributions for the period 1961–1990. All models projected the British climate during this period to be suitable for both species. Thirty-year climate projections for the periods 1991–2020 and 2021–2050, and for three climate change scenarios, were then put into the models to generate projections of climatic suitability throughout the 21st century. British climate was projected to remain highly suitable for A. crataegi, but to decline somewhat for P. semiargus. Southern and eastern Britain were found to be the areas most likely to support suitable climate. This difference between the species appeared to be due in part to decreasing summer rainfall in climate change projections, as this should only benefit A. crataegi. It is concluded that, with further study of habitat requirements, both species could be reintroduced to Britain as part of a long-term European conservation strategy.     

Agricultural intensification, rainfall patterns, and large waterbird breeding success in the extensively cultivated landscape of Uttar Pradesh, India

In countries with high human populations, using agricultural areas as multifunctional systems to produce food for humans and retain wildlife may be an efficient conservation strategy for many species. Inclusion of natural habitat and species requirements on agricultural landscapes explicitly into planning processes are precluded by lack of information on drivers of species persistence. Climate change is an additional emerging complexity, and adaptation plans for agricultural landscapes are biased towards intensification to secure long-range food production. I examine the conservation potential of an agricultural landscape in two districts of Uttar Pradesh, north India where agricultural intensification and altered rainfall patterns are predicted to occur. I assess stressors affecting breeding success over eight years of two large waterbirds of conservation concern – Sarus Cranes and Black-necked Storks. Both species had high breeding success that improved with total rainfall and more wetlands in breeding territories. Agricultural and township expansions deteriorated territory quality and reduced breeding success. Sarus Crane populations were predicted to decline relatively rapidly if development activities continued to displace breeding pairs. Black-necked Storks appeared resilient over the long-term notwithstanding reduced breeding success in low-rainfall years. Waterbird nesting habitats (wetlands and trees) were retained in Uttar Pradesh as community lands by villages and by state government via legal provisions suggesting the utility of multiple conservation approaches. Incorporating species requirements explicitly, alongside traditional land use practices conducive for habitat conservation, into adaptation planning and conservation policy will be necessary to retain long-term multifunctionality of such agricultural landscapes.     

Biodiversity management in the face of climate change: A review of 22 years of recommendations

Climate change creates new challenges for biodiversity conservation. Species ranges and ecological dynamics are already responding to recent climate shifts, and current reserves will not continue to support all species they were designed to protect. These problems are exacerbated by other global changes. Scholarly articles recommending measures to adapt conservation to climate change have proliferated over the last 22 years. We systematically reviewed this literature to explore what potential solutions it has identified and what consensus and direction it provides to cope with climate change. Several consistent recommendations emerge for action at diverse spatial scales, requiring leadership by diverse actors. Broadly, adaptation requires improved regional institutional coordination, expanded spatial and temporal perspective, incorporation of climate change scenarios into all planning and action, and greater effort to address multiple threats and global change drivers simultaneously in ways that are responsive to and inclusive of human communities. However, in the case of many recommendations the how, by whom, and under what conditions they can be implemented is not specified. We synthesize recommendations with respect to three likely conservation pathways: regional planning; site-scale management; and modification of existing conservation plans. We identify major gaps, including the need for (1) more specific, operational examples of adaptation principles that are consistent with unavoidable uncertainty about the future; (2) a practical adaptation planning process to guide selection and integration of recommendations into existing policies and programs; and (3) greater integration of social science into an endeavor that, although dominated by ecology, increasingly recommends extension beyond reserves and into human-occupied landscapes.     

Assessing the potential impacts of climate change and their conservation implications in Japan: A case study of conifers

The Japanese archipelago is a biodiversity hotspot with a unique regional climate influenced by the Asian monsoon circulation, surrounding seas, and complex topography. Japan has numerous mountains and islands, which are potentially vulnerable to climate change. This study evaluated the potential impact of climate change on species diversity in Japan, using 25 conifer tree species as a case study. We applied ensemble models based on generalised additive models, artificial neural networks, generalised boostedmodels, and random forests to species’ locality records at 1 km² resolution. The results indicated a substantial impact, such that 80% of the species may lose over half of their current climatically suitable areas by 2100. The lower altitudinal range limits were projected to shift upwards by 293 m on average, suggesting that alpine/sub-alpine and sub-boreal species may face widespread local extinctions. The impacts on sub-alpine species may be moderated by assisted migration to the northern island where they currently do not occur. However, climatically suitable areas for these species and sub-boreal species that occur on the island overlapped significantly, indicating that assisted migration may entail the risk of introducing biotic competition or interbreeding. Thus, rugged topography and dispersal barriers between islands are likely to amplify the future impacts of climate change in Japan. Limited areas in the central mountain region were identified as potential bioclimatic refugia, which should be conserved as a priority.     

Terrestrial microarthropods of Victoria Land and Queen Maud Mountains, Antarctica: Implications of climate change

We review aspects of climate change likely to impact upon the Collembola and mites (microarthropods) of Victoria Land and the Queen Maud Mountains (VLQMM) in the Ross Sea Region of Antarctica. Five important aspects of biological and biological-environmental interactions are identified as key for understanding the impact of climate change on VLQMM microarthropods: (1) Water availability and utilization; (2) mean temperature (which will affect development and population processes) and extreme temperatures (which affect persistence); (3) ultraviolet radiation, although we note that the periods of peak UV irradiance and microarthropod activity do not coincide; (4) dispersal within and between habitats; and (5) potential establishment of invasive species from within and without Antarctica. The current evidence for effects of climate change on VLQMM microarthropods is equivocal, and we advocate targeted experimental and monitoring studies. Finally, we highlight several areas of high priority for future research, particularly on the mite fauna for which detailed information is currently lacking. These are: (1) functional ecology (including thermal biology, feeding and nutrition and water relations); (2) distribution, dispersal and colonization processes and (3) population and community ecology.     

Misleading results from conventional gap analysis – Messages from the warming north

Gap analysis is a widely used method for assessing the representation of species in protected area (PA) networks. However, representation does not imply persistence. Here, we investigated whether gap analysis may result in misleading conservation guidelines by comparing the representation to two indicators of persistence. We ran a gap analysis with Finnish breeding birds and identified conservation priorities based on current distribution patterns. We tested the sensitivity of these results by using two target setting schemes and several thresholds defining the amount of protected area, and found the levels of representation identified by gap analysis to be robust. We then compared the gap analysis results with recent population trends and projected changes in potential suitable climate under different climate change scenarios for the year 2050. We show that although high latitude species are well represented in PAs, they are currently declining and are projected to lose climatic suitability in the near future. In contrast, low latitude species with poor representation in PAs have increasing population trends and are generally expected to expand their ranges into protected areas in the near future. This study demonstrates with empirical data a mismatch between representation in PAs and population trends, resulting in misleading understanding of current PA effectiveness. The mismatch is linked to the latitude of species distributions and corresponds to expected future changes, indicating that the patterns are potentially driven by climate change. We therefore urge practitioners and researchers to include better indicators of persistence in gap-analysis frameworks even for short term assessments.     

Will climate change reduce the efficacy of protected areas for amphibian conservation in Italy?

Amphibians are an important and imperiled component of biodiversity. In this study we analyze the efficacy of Italian reserve network for protecting multiple amphibian species in a climate change scenario, considering both nationally designated areas and Natura 2000 sites. Our approach is based on ensemble niche modeling estimate of potential range shift under two carbon emission scenarios (A1FI and B1) and two dispersal assumptions. The predicted distributions were used to perform gap and irreplaceability analyses. Our findings show that the current Italian reserve network incompletely represents current amphibian diversity and its geographic pattern. The combination of the nationally designated protected areas and the Natura 2000 sites improves current representation of amphibians, but conservation targets based on geographic range extent are achieved for only 40% of species. Under the future scenarios, Natura 2000 sites become a crucial component of the protected areas system. Nonetheless, we predict that climate change decreases for many species the amount of suitable range falling into reserves, regardless of our assumptions about dispersal. We identify some currently unprotected areas that have high irreplaceability scores for species conservation and that maintain their importance under all the future scenarios we considered. We recommend designation of new reserves in these areas to help guarantee long-term amphibian conservation.     

Impacts of climate change on Swiss biodiversity: An indicator taxa approach

We present a new indicator taxa approach to the prediction of climate change effects on biodiversity at the national level in Switzerland. As indicators, we select a set of the most widely distributed species that account for 95% of geographical variation in sampled species richness of birds, butterflies, and vascular plants. Species data come from a national program designed to monitor spatial and temporal trends in species richness. We examine some opportunities and limitations in using these data. We develop ecological niche models for the species as functions of both climate and land cover variables. We project these models to the future using climate predictions that correspond to two IPCC 3rd assessment scenarios for the development of ‘greenhouse’ gas emissions. We find that models that are calibrated with Swiss national monitoring data perform well in 10-fold cross-validation, but can fail to capture the hot-dry end of environmental gradients that constrain some species distributions. Models for indicator species in all three higher taxa predict that climate change will result in turnover in species composition even where there is little net change in predicted species richness. Indicator species from high elevations lose most areas of suitable climate even under the relatively mild B2 scenario. We project some areas to increase in the number of species for which climate conditions are suitable early in the current century, but these areas become less suitable for a majority of species by the end of the century. Selection of indicator species based on rank prevalence results in a set of models that predict observed species richness better than a similar set of species selected based on high rank of model AUC values. An indicator species approach based on selected species that are relatively common may facilitate the use of national monitoring data for predicting climate change effects on the distribution of biodiversity.     

Projecting the local impacts of climate change on a Central American montane avian community

Significant changes in the climates of Central America are expected over the next century. Lowland rainforests harbor high alpha diversity on local scales (<1 km²), yet montane landscapes often support higher beta diversity on 10-100 km² scales. Climate change will likely disrupt the altitudinal zonation of montane communities that produces such landscape diversity. Projections of biotic response to climate change have often used broad-scale modelling of geographical ranges, but understanding likely impacts on population viability is also necessary for anticipating local and global extinctions. We model species’ abundances and estimate range shifts for birds in the Tilarán Mountains of Costa Rica, asking whether projected changes in temperature and rainfall could be sufficient to imperil high-elevation endemics and whether these variables will likely impact communities similarly. We find that nearly half of 77 forest bird species can be expected to decline in the next century. Almost half of species projected to decline are endemic to Central America, and seven of eight species projected to become locally extinct are endemic to the highlands of Costa Rica and Panamá. Logistic-regression modelling of distributions and similarity in projections produced by temperature and rainfall models suggest that changes in both variables will be important. Although these projections are probably conservative because they do not explicitly incorporate biological or climate variable interactions, they provide a starting point for incorporating more realistic biological complexity into community-change models. Prudent conservation planning for tropical mountains should focus on regions with room for altitudinal reorganization of communities comprised of ecological specialists.     

Woodland networks in a changing climate: Threats from land use change

Landscape adaptation to climate change requires policies that facilitate species dispersal, to counteract the effects of fragmentation and allow tracking of a species’ ‘climatic niche’. Expanding existing ecological networks is often proposed as a measure to maintain functional connectivity for forest species in multi-functional landscapes.In the next decades, however, such networks will be threatened by climate change through its effects on land use change, as global drivers are likely to have an increasing influence on national land use policy. Evaluation of indirect effects of climate change, on habitat networks, mediated by land use change, is therefore needed. We used an approach integrating climate, soil properties, and landscape resistance to dispersal, the latter estimated using Circuit Theory, to evaluate the vulnerability to land use change of forest habitat networks in Scotland, given two scenarios of land use change. In Scotland a combination of high food prices and improved land capability for agriculture could lead to decreased landscape connectivity for woodland species, especially in the East and South, with potentially large trade-offs between agriculture and woodland connectivity in the case of loss of woodland on prime agricultural land. We suggest that planning of ecological networks needs to account for future land use change. Adaptation and mitigation strategies across multiple sectors should be reconciled. Woodland networks will benefit from minimising creation of new woodlands on future prime agricultural land, the protection of existing patches, and the creation of wide-scale dispersal pathways along climatic gradients, i.e. in the N–S and E–W directions.     

气候变化对我国森林生态的影响

阐述了气候变化对我国森林地理分布格局、物候期、生物多样性、森林结构及生产力的影响。研究表明,气候变化对我国主要造林树种地理分布的影响多发生在气候交错地带,少部分发生在适宜分布区域,树种分布可能向北或向高海拔地区移动;不同区域树种物候期推迟或提前,原区域的适宜物种减少,新物种随气候变化迁入;气候变化基本未改变我国森林第一性生产力的地理分布格局,但群落生物量水平将有所提高,不同树种森林结构变化不同。通过采取积极的适应性措施可降低气候变化的不利影响。     

Conservation strategies in response to rapid climate change: Australia as a case study

As in all parts of the globe, rapid climate change in Australia will have significant negative impacts on biodiversity. It also will interact with pre-existing stressors such as native vegetation clearing, altered natural disturbance regimes and invasive species - all of which already have major negative effects on biota in Australia. Strategies to reduce climate change impacts on Australian biodiversity include a mixture of mitigation and adaptation actions (sensuMillar et al., 2007) such as: (1) significantly reducing greenhouse gas emissions, (2) ensuring bio-diverse carbon capture, (3) better tackling pre-existing stressors on biodiversity, (4) better preparing for the effects of major natural disturbances, (5) significantly improving off-reserve conservation efforts including fostering appropriate connectivity, and (6) enhancing the existing reserve system by making it more comprehensive, adequate and representative. The first strategy above demands a global response otherwise major mitigation attempts in Australia that are not paralleled elsewhere around the world will have little effect on climate change and, in turn, contribute little to enhanced biodiversity conservation. Strategies 2-6 demand multi-scaled responses, particularly at a regional level, given the major regional differences in direct climate change impacts and their interactions with pre-existing regional stressors. Well developed multi-scaled conservation plans to implement these strategies currently do not exist, nor do appropriate institutional arrangements and capacities. Institutional reforms are urgently needed in Australia to develop the land management, monitoring and regional response capabilities required to conserve biodiversity on a continent already significantly modified.     

Climate change meets habitat fragmentation: linking landscape and biogeographical scale levels in research and conservation

Climate change and habitat fragmentation are considered key pressures on biodiversity. In this paper we explore the potential synergetic effects between these factors. We argue that processes at two levels of spatial scale interact: the metapopulation level and the species range level. Current concepts of spatially dynamic metapopulations and species ranges are consistent, and integration improves our understanding of the interaction of landscape level and geographical range level processes. In landscape zones in which the degree of habitat fragmentation allows persistence, the shifting of ranges is inhibited, but not blocked. In areas where the spatial cohesion of the habitat is below the critical level of metapopulation persistence, the expansion of ranges will be blocked. An increased frequency of large-scale disturbances caused by extreme weather events will cause increasing gaps and an overall contraction of the distribution range, particularly in areas with relatively low levels of spatial cohesion. Taking into account the effects of climate change on metapopulations, habitat distribution and land use changes, future biodiversity research and conservation strategies are facing the challenge to re-orient their focus and scope by integrating spatially and conceptually more dynamic aspects at the landscape level.