Genealogies of scientifically induced biomobilities: Restoration ecology under climate emergency

The Torreya Guardians are trying to save the Florida torreya (Torreya taxifolia Arn.) from extinction (Barlow & Martin 2004). Fewer than 1000 individuals of this coniferous tree remain within its native distribution, a 35-km stretch of the Apalachicola River, and these trees are not reproducing (Schwartz et al. 2000). Even if the Florida torreya was not declining toward extinction, the species would be at risk from climate change. Warming is projected to either significantly reduce or eliminate suitable habitat for most narrowly endemic taxa (Thomas et al. 2004; Hannah et al. 2005; Peterson et al. 2006), forcing species to colonize new terrain to survive. The focus of the Torreya Guardians is an “assisted migration” program that would introduce seedlings to forests across the Southern Appalachians and Cumberland Plateau (http://www.TorreyaGuardians.org). Their intent is to avert extinction by deliberately expanding the range of this endangered plant over 500 km northward. Because planting endangered plants in new environments is relatively simple as long as seeds are legally acquired and planted with landowner permission, the Torreya Guardians believe their efforts are justified. Introducing this species to regions where it has not existed for 65 million years is “[e]asy, legal, and cheap” (Barlow & Martin 2004). If circumventing climate-driven extinction is a conservation priority, then assisted migration must be considered a management option. Compelling evidence suggests that climate change will be a significant driver of extinction (McCarthy et al. 2001; McLaughlin et al. 2002; Root et al. 2003; Thomas et al. 2004). Researchers typically conclude that mitigating climate change and providing reserve networks that foster connectivity and movement should be a priority (e.g., Hannah et al. 2002). Ecol-

Ecological restoration, when implemented effectively and sustainably, contributes to protecting biodiversity; improving human health and wellbeing; increasing food and water security; delivering goods, services, and economic prosperity; and supporting climate change mitigation, resilience, and adaptation. It is a solutions-based approach that engages communities, scientists, policymakers, and land managers to repair ecological damage and rebuild a healthier relationship between people and the rest of nature. When combined with conservation and sustainable use, ecological restoration is the link needed to move local, regional, and global environmental conditions from a state of continued degradation, to one of net positive improvement. The second edition of the International Principles and Standards for the Practice of Ecological Restoration (the Standards) presents a robust framework for restoration projects to achieve intended goals, while addressing challenges including effective design and implementation, accounting for complex ecosystem dynamics (especially in the context of climate change), and navigating trade-offs associated with land management priorities and decisions.

Reconstructing a deconstructed concept: Policy tools for implementing assisted migration for species and ecosystem management

Can assisted tree migration today sustain forest ecosystem goods and services for the future?

Climate change obliges societies to develop adaptive strategies in order to maintain sustainable management of resources and landscapes. However, the development and implementation of these strategies require dialogue between researchers and policy‐makers about what they understand for adaptation. This dialogue can be hindered by language differences, the hidden agendas, and conflicting concerns of those involved. In this research study, we explored the mechanisms that underlie the implementation process of assisted migration (AM), an adaptation strategy that aims to limit the impact of climate change. We conducted a comparative analysis of 80 semistructured interviews with actors in the forestry sectors in Canada and France. In Canada, our results show a division between the provinces strategies, causing a debate about AM because researchers are wary of the geoengineering and economic arguments that frame AM in areas where the effects of climate change remain unclear. In contrast, we found that the observation of climate impacts is a strong trigger for the application of AM despite an awareness of its associated risks. In France, we explained the absence of AM implementation by a lack of information flow between research and foresters regarding the concept of AM, a cultural attachment of French foresters to their forest landscapes and that climate change effects are not clear yet. Clarity on what implies a true ecological engineering approach in ecological restoration can help maintaining adaptive actions like AM within the general scope of ecosystem management and minimize simplistic applications of adaptation strategies because of climate change.

Managed relocation is a critical tool for promoting ecological resilience in the face of climate change, and the approach has been proposed for the ecological restoration of plant communities. Given that the relocation of species poses some risk to the recipient ecosystem, plant traits associated with invasiveness have been proposed as a means for assessing risk and selecting candidate species for managed relocation. However, traits associated with invasiveness could also be relevant to successful restoration (and, in turn, for successful managed relocation)-particularly those linked to the establishment of viable populations. Here, we review studies in invasion and restoration ecology that have paired plant functional, ecological, and biogeographic traits with stages of invasion or successful restoration to ask which traits should be used to inform managed relocation species selection. We find substantial overlap between invasiveness traits and restoration traits during population establishment, but divergence during spread and impacts, suggesting that managed relocation species selection should only focus on traits that promote long-distance spread and impact. Instead, the few existing protocols for managed relocation species selection utilize traits that promote establishment. Given that the risk of unintended harm from managed relocation is orders of magnitude smaller than from non-native plant introduction, focusing on traits that promote establishment in risk assessments is likely to exclude those species most able to establish viable populations, causing failure rates in managed relocation. Instead, we recommend that risk assessments for managed relocation candidates focus on traits linked to invasive species spread or impacts and which are not necessary for restoration. Given the substantial ecological threats posed by climate change, a balanced approach to risk assessment that does not severely limit candidate species will best support successful managed relocation as a climate adaptation strategy.

The rapidity of climate change is predicted to exceed the ability of many species to adapt or to disperse to more climatically favorable surroundings. Conservation of these species may require managed relocation (also called assisted migration or assisted colonization) of individuals to locations where the probability of their future persistence may be higher. The history of non-native species throughout the world suggests managed relocation may not be applicable universally. Given the constrained existence of freshwater organisms within highly dendritic networks containing isolated ponds, lakes, and rivers, managed relocation may represent a useful conservation strategy. Yet, these same distinctive properties of freshwater ecosystems may increase the probability of unintended ecological consequences. We explored whether managed relocation is an ecologically sound conservation strategy for freshwater systems and provided guidelines for identifying candidates and localities for managed relocation. A comparison of ecological and life-history traits of freshwater animals associated with high probabilities of extirpation and invasion suggests that it is possible to select species for managed relocation to minimize the likelihood of unintended effects to recipient ecosystems. We recommend that translocations occur within the species' historical range and optimally within the same major river basin and that lacustrine and riverine species be translocated to physically isolated seepage lakes and upstream of natural or artificial barriers, respectively, to lower the risk of secondary spread across the landscape. We provide five core recommendations to enhance the scientific basis of guidelines for managed relocation in freshwater environments: adopt the term managed translocation to reflect the fact that individuals will not always be reintroduced within their historical native range; examine the trade-off between facilitation of individual movement and the probability of range expansion of non-native species; determine which species and locations might be immediately considered for managed translocation; adopt a hypothetico-deductive framework by conducting experimental trials to introduce species of conservation concern into new areas within their historical range; build on previous research associated with species reintroductions through communication and synthesis of case studies.

Integrated spatial planning for biodiversity conservation and food production

Moving species outside their natural ranges has long been recognized as risky (“Home, home outside the range?”, R. Stone, News Focus, 24 September, p. [1592][1]). Current accepted procedure allows for translocations outside the historic range only reactively—when there is no suitable habitat left in that range ([ 1 ][2]). For example, flightless birds such as kakapo and takahe have been introduced to offshore islands because exotic mammalian predators had rendered them unable to persist on the New Zealand mainland. Soon, we may have to move species proactively as a means to save them from anticipated shifts in habitat due to climate change. Proactive assisted colonization is understandably contentious. The best way forward involves careful modeling and collaboration. There are many cautionary experiences from invasive species and biological control releases ([ 2 ][3]). However, tools such as structured decision-making enable us to make decisions in the face of uncertainty about ecological roles and relationships that we will have least cause to regret. We can construct models around the fate of species if we leave them to face climate change either by adapting, by moving, or by dying out. We can explore a deliberately moved species' prospects of (i) dying out at its human-selected destination, (ii) establishing and becoming a pest, or (iii) settling down within desired population limits. The test case in the News story of the two butterflies in the United Kingdom ([ 3 ][4]) is an example of the low-risk and potentially reversible type of experiment that we should be starting now. With assisted migration recognized as one means to reduce the impacts of climate change on biodiversity ([ 4 ][5]), we need international guidelines on the conditions under which it may be an acceptable solution. Consequently, the IUCN Species Survival Commission has established a task force from within its Re-introduction and Invasive Species Specialist Groups to review and update its 1998 guidelines to explicitly accommodate these issues surrounding assisted colonization. The task force will report to the World Conservation Congress in 2012. 1. [↵][6]IUCN/SSC Re-introduction Specialist Group, “Guidelines for re-introductions” (IUCN, Gland, Switzerland, 1998). 2. [↵][7]1. A. Ricciardi, 2. D. Simberloff , Trends Ecol. Evol. 24, 248 (2009). [OpenUrl][8][CrossRef][9][PubMed][10][Web of Science][11] 3. [↵][12]1. S. G. Willis 2. et al ., Conserv. Lett. 2, 45 (2009). [OpenUrl][13] 4. [↵][14]CBD, Conference of the Parties, “Biodiversity and climate change” (UNEP/CBD/COP/10/L.36, 2010). [1]: pending:yes [2]: #ref-1 [3]: #ref-2 [4]: #ref-3 [5]: #ref-4 [6]: #xref-ref-1-1 View reference 1 in text [7]: #xref-ref-2-1 View reference 2 in text [8]: {openurl}?query=rft.jtitle%253DTrends%2Bin%2BEcology%2B%2526%2BEvolution%26rft.stitle%253DTrends%2Bin%2BEcology%2B%2526%2BEvolution%26rft.aulast%253DRicciardi%26rft.auinit1%253DA.%26rft.volume%253D24%26rft.issue%253D5%26rft.spage%253D248%26rft.epage%253D253%26rft.atitle%253DAssisted%2Bcolonization%2Bis%2Bnot%2Ba%2Bviable%2Bconservation%2Bstrategy.%26rft_id%253Dinfo%253Adoi%252F10.1016%252Fj.tree.2008.12.006%26rft_id%253Dinfo%253Apmid%252F19324453%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [9]: /lookup/external-ref?access_num=10.1016/j.tree.2008.12.006&link_type=DOI [10]: /lookup/external-ref?access_num=19324453&link_type=MED&atom=%2Fsci%2F330%2F6009%2F1317.1.atom [11]: /lookup/external-ref?access_num=000266188100005&link_type=ISI [12]: #xref-ref-3-1 View reference 3 in text [13]: {openurl}?query=rft.jtitle%253DConserv.%2BLett.%26rft.volume%253D2%26rft.spage%253D45%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [14]: #xref-ref-4-1 View reference 4 in text

Purpose of ReviewAssisted migration is increasingly proposed as a proactive management strategy to mitigate the consequences of maladaptation predicted under climate change. Exploring the social and academic structure of the field, its research gaps, and future research directions can help further the understanding and facilitate the implementation of assisted migration strategies. Here we used bibliometric analysis to examine the intellectual, social, and conceptual structures of assisted migration research to identify gaps and opportunities for future research. Bibliometric data based on publications on assisted migration were collected from Scopus and Web of Science databases using assisted migration and climate change or their synonyms as queries. Metadata were merged, processed and several networks were constructed.Recent FindingsCo-citation and keyword co-occurrence networks identified three major clusters focused on (i) theory and risk of assisted migration of threatened and endangered species, (ii) impact of climate change on realized and fundamental climate and geographic niches, and (iii) assisted population migration. Collaboration network analysis identified three social core hubs: North America, Europe, and Australia, with the USA and Canada being the most productive and the most collaborative countries.SummaryWe conclude that future research is expected to concern mainly the assessment of physiological response of species and populations to extreme climate events such as drought and frost, and the contribution of non-climatic factors and biotic interactions in local adaptation and population performance under climate change. Social core hubs distinguished in this work can be used to identify potential international research and training collaborators necessary to address gaps and challenges underlying assisted migration implementation.

Assisted migration is a controversial conservation measure that includes moving species threatened by climate change beyond their indigenous range. Sandler argues that assisted migration exhausts most of the value of the species moved and that assisted migration, thus, fails to be a workable conservation measure. We show how accepting the moral relevance of species’ indigenous range helps to reconcile Sandler's argument with earlier arguments about value loss in ecosystem restoration by Elliot and Katz. Contrary to Sandler, they do not favour losing a biological unit to retaining it in a human-influenced form. Drawing on the distinction between property- and history-based understandings of naturalness, we further argue that the outcomes of assisted migration to the predicted range are more natural in the property-based sense of the term, and thus retain more value, than the outcomes of ‘‘assisted migration'’ elsewhere.

Altitudinal range shift detected through seedling survival of Ceiba aesculifolia in an area under the influence of an urban heat island

Summary Climate change is affecting the spatio‐temporal distribution of environmental conditions, forcing species to shift their range in response. Species not capable of dispersing naturally may benefit from conservation translocations. A key aspect of translocation planning is release site selection: under the 2012 IUCN guidelines for reintroductions and other conservation translocations, selected sites are expected to match the biotic and abiotic needs of the candidate species now and in the future. Here we present a methodological framework to identify optimal translocation sites under climate change. Our method is the first to explicitly combine statistical and predictive population modelling to understand the relationship between climate, climate change and population dynamics, in order to perform robust habitat suitability analyses for conservation decision‐making. We use the hihi Notiomystis cincta, a bird endemic to New Zealand, as a case study. We focus on the population of Tiritiri Matangi Island, which has been provided with ad libitum supplementary food since 1996. This offers the unique opportunity to study the direct impact of climate and future change in climatic conditions on a population free of confounding constraints. Climate is found to drive hihi population dynamics, even though they are not limited by the availability of food. Thus, despite the current management of the species, climate change remains a major threat to its long‐term persistence. Moreover, under predicted climate change for the country, hihi suitable habitat will shift southward: the two current largest hihi populations will face unsuitable climatic conditions in the coming decades, and habitat that was not part of the species' historical range may become suitable. Synthesis and applications. Assisted colonization is increasingly being considered as an adaptation tool for species threatened by climate change. Justifying the use of this extreme conservation action, however, requires robust evidence that it is necessary and clear guidance on where to translocate individuals of threatened populations. We show how both requirements can be met using habitat suitability modelling if knowledge of the relationship between climate, climate change and the species' population dynamics is systematically used to guide the modelling process.

Restoration programs need to increasingly address both the restitution of biodiversity and ecosystem services and the preparation of habitats for future climate change. One option to adapt habitats to climate change in the temperate zone is the translocation of southern populations to compensate for climate change effects—an option known as assisted migration (AM). Although AM is widely criticized for endangered species, forest managers are more confident that tree populations can be translocated with success because of previous experiences within native ranges. Here, we contend that translocations of tree populations are also subject to uncertainties, and we extract lessons for future programs of AM within species ranges from a well‐documented failed case of population translocation of Pinus pinaster Ait. in Europe. The failure of these translocations originated from the unawareness of several unpredictable ecological and social events: cryptic maladaptation of the introduced populations, underestimation of climate variability differences between the source and target sites, and complexity in the management schemes, postponing decisions that could have been undertaken earlier. Under the no‐analog conditions that are expected with climate change, management decisions need to be made with incomplete data, implying that a certain degree of maladaptation should always be expected when restoring plant populations from local or external seed sources.

The right tree at the right place? Exploring urban foresters’ perceptions of assisted migration