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Landscape connectivity improves species’ capacity to adapt to climate change. These models are increasingly needed and available for climate-change conservation planning. However, their relative strengths and weaknesses are unclear. We asked how well do the spatial outputs from four connectivity models intended to support climate change conservation agree? To understand the implications of selecting one or several approaches, we compared various combinations of four connectivity models for ecoregions in California, U.S.A. Two models are based on landscape structure, Land Facet Corridors and Omniscape, while two other models, Meta-Corridor Approach and Network Flow Analysis (NFA), use focal species’ range dynamics to determine connectivity. We also describe how each approach integrates climate-adaptive connectivity concepts. Variation in modeling methods, objectives, inputs, and landscape representations strongly affects the modeled connectivity patterns. For the region where all four models were run, almost three quarters of the landscape was selected by one or more models, but three or more agree for only 9.5% of the area, all of which is riparian. This emphasizes the importance of riparian areas for climate adaptation. We found NFA prioritized connections close to protected areas, while Meta-Corridor avoided higher cost agricultural and developed areas. The structural models agreed in areas with low human impact but Omniscape avoided areas of low topographic diversity and Land Facet Corridors avoided connections in areas with no protected areas. Connectivity models should be selected based on the conservation objectives, such as spatial scale to be implemented, and a combination of models may be best.

In response to biodiversity declines worldwide, over 190 nations committed to protect 30% of their lands and waters by 2030 (hereafter, 30×30). Systematic conservation planning and return on investment analysis can be helpful tools for determining where protection efforts could deliver the most efficient and effective reserve design, and supporting decision‐making when trade‐offs among objectives are required. Here, we propose a framework for efficient "30×30" implementation and apply it to the state of California (USA). Because conservation of a region's full suite of biodiversity is the primary objective of the global initiative, we prioritized representation in our analysis. We used Zonation to identify networks that close the gap in representation of major habitat types in California's protected area network and that also conserve the places important for biodiversity or climate change mitigation. We identified networks that are efficient relative to metrics likely to be important in implementation including land acquisition cost, number of transactions, and conservation benefit per hectare, and we illustrate not only trade‐offs associated with these metrics but also differences in the co‐benefits achieved. Five of the eight major habitat types in California are not currently protected at a 30% level statewide, and if representation was achieved solely through private land acquisition, targets could be met for as little as $5.84 billion, with as few as 364 transactions, or with 2.18 million additional conserved hectares. Implementation of 30×30 will likely require more flexibility than a single network design. A "no regrets" action would be to protect properties that were prioritized across all networks and additional implementation should include properties with characteristics of any of the individual networks. Our analytical framework and implementation guidance can be applied to other geographies and jurisdictions to increase the likelihood of both meeting 30×30 targets and delivering the conservation benefits they aim to secure. [ABSTRACT FROM AUTHOR]

Although a plethora of habitat-connectivity plans exists, protecting and restoring connectivity through on-the-ground action has been slow. We identified challenges to and opportunities for connectivity conservation through a literature review of project implementation, a workshop with scientists and conservation practitioners, 3 case studies of connectivity projects, and interviews with conservation professionals. Connectivity challenges and solutions tended to be context specific, dependent on land-ownership patterns, socioeconomic factors, and the policy framework. Successful connectivity implementation tended to be associated with development and promotion of a common vision among diverse sets of stakeholders, including nontraditional conservation actors, such as water districts and recreation departments, and with communication with partners and the public. Other factors that lead to successful implementation included undertaking empirical studies to prioritize and validate corridors and the identification of related co-benefits of corridor projects. Engaging partners involved in land management and planning, such as nongovernmental conservation organizations, public agencies, and private landowners, is critical to effective strategy implementation. A clear regulatory framework, including unambiguous connectivity conservation mandates, would increase public resource allocation, and incentive programs are needed to promote private sector engagement. Connectivity conservation must move more rapidly from planning to implementation. We provide an evidence-based solution composed of key elements for successful on-the-ground connectivity implementation. We identified the social processes necessary to advance habitat connectivity for biodiversity conservation and resilient landscapes under climate change.

Empirical studies and habitat suitability modeling project significant shifts in species distributions in response to climate change. Because habitat fragmentation can impede species range shifts, wildlife corridors may have increasing importance in enhancing climate resilience for species persistence. While habitat connectivity has been studied for over four decades, the design of connectivity specifically to facilitate species movement in response to climate change is a relatively new challenge. We conducted a systematic review of 116 relevant papers from 1996–2017. Research focused on assessing the utility of habitat connectivity for climate change adaptation by species (N = 29) and modeling and mapping climate-wise connectivity for planning purposes (N = 55). Others addressed fundamental questions of connectivity related to climate adaptation (N = 31). Based on empirical data and computer simulations examining species range shifts in response to climate change at leading edges of current distributions; it is clear that large protected areas connected through linkages, and stepping stones embedded in a permeable matrix promote population persistence and facilitate range expansion. We identified 13 approaches to modeling climate-wise connectivity based on either focal species or landscape structure. When prioritizing areas for connectivity conservation, approaches include focusing on connecting areas of low climate velocity, refugia, climate analogs, or linking current to future suitable habitats. Riparian corridors should be considered in connectivity plans because of their importance as natural movement corridors, climate gradients, and refugia. Guidance is provided on selecting the best methods for connectivity design depending on the objectives, available data, and landscape context. Future research needs to evaluate the functionality of climate-wise connectivity models for facilitating range shifts and compare connectivity outcomes across modeling approaches.

Balancing society's competing needs of development and conservation requires careful consideration of tradeoffs. Renewable energy development and biodiversity conservation are often considered beneficial environmental goals. The direct footprint and disturbance of renewable energy, however, can displace species' habitat and negatively impact populations and natural communities if sited without ecological consideration. Offsets have emerged as a potentially useful tool to mitigate residual impacts after trying to avoid, minimize, or restore affected sites. Yet the problem of efficiently designing a set of offset sites becomes increasingly complex where many species or many sites are involved. Spatial conservation prioritization tools are designed to handle this problem, but have seen little application to offset siting and analysis. To address this need we designed an offset siting support tool for the Desert Renewable Energy Conservation Plan (DRECP) of California, and present a case study of hypothetical impacts from solar development in the Western Mojave subsection. We compare two offset scenarios designed to mitigate a hypothetical 15,331 ha derived from proposed utility-scale solar energy development (USSED) projects. The first scenario prioritizes offsets based precisely on impacted features, while the second scenario offsets impacts to maximize biodiversity conservation gains in the region. The two methods only agree on 28% of their prioritized sites and differ in meeting species-specific offset goals. Differences between the two scenarios highlight the importance of clearly specifying choices and priorities for offset siting and mitigation in general. Similarly, the effects of background climate and land use change may lessen the durability or effectiveness of offsets if not considered. Our offset siting support tool was designed specifically for the DRECP area, but with minor code modification could work well in other offset analyses, and could provide continuing support for a potentially innovative mitigation solution to environmental impacts.

As both plant and animal species shift their ranges in response to a changing climate, maintaining connectivity between present habitat and suitable habitat in the future will become increasingly important to ensure lasting protection for biodiversity. Because the temporal period commensurate with planning for mid‐century change is multi‐generational for most species, connectivity designed to facilitate climate adaptation requires pathways with 'stepping‐stones' between current and future habitat. These areas should have habitats suitable not only for dispersal, but for all aspects of species lifecycles. We integrated present‐day land use, topographic diversity, and projections of shifting climate regimes into a single connectivity modeling approach to identify pathways for mid‐century shifts in species ranges. Using Omniscape we identified climate linkages, or areas important for climate change‐driven movement, as the areas with more current flow than would be expected in the absence of climate considerations. This approach identified connectivity potential between natural lands in the present climate and natural lands with future analogous climate following topo‐climatically diverse routes. We then translated the model output into a strategic framework to improve interpretation and to facilitate a more direct connection with conservation action. Across modified landscapes, pathways important to climate‐driven movement were highly coincident with the last remaining present‐day linkages, reinforcing their importance. Across unfragmented lands, the presence of climate‐adapted pathways helped inform the prioritization of conservation actions in areas where multiple connectivity options still exist. Many climate linkages follow major watercourses along elevational gradients, highlighting the importance of protecting or managing for these natural linear pathways that provide movement routes for climate adaptation. By integrating enduring landscape features with climate projections and present‐day land uses, our approach reveals "no‐regrets" pathways to plan for a connected landscape in an uncertain future. [ABSTRACT FROM AUTHOR]

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