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Conservation practitioners have long recognized ecological connectivity as a global priority for preserving biodiversity and ecosystem function. In the early years of conservation science, ecologists extended principles of island biogeography to assess connectivity based on source patch proximity and other metrics derived from binary maps of habitat. From 2006 to 2008, the late Brad McRae introduced circuit theory as an alternative approach to model gene flow and the dispersal or movement routes of organisms. He posited concepts and metrics from electrical circuit theory as a robust way to quantify movement across multiple possible paths in a landscape, not just a single least-cost path or corridor. Circuit theory offers many theoretical, conceptual, and practical linkages to conservation science. We reviewed 459 recent studies citing circuit theory or the open-source software Circuitscape. We focused on applications of circuit theory to the science and practice of connectivity conservation, including topics in landscape and population genetics, movement and dispersal paths of organisms, anthropogenic barriers to connectivity, fire behavior, water flow, and ecosystem services. Circuit theory is likely to have an effect on conservation science and practitioners through improved insights into landscape dynamics, animal movement, and habitat-use studies and through the development of new software tools for data analysis and visualization. The influence of circuit theory on conservation comes from the theoretical basis and elegance of the approach and the powerful collaborations and active user community that have emerged. Circuit theory provides a springboard for ecological understanding and will remain an important conservation tool for researchers and practitioners around the globe.Aplicaciones de la Teoría de Circuitos a la Conservación y a la Ciencia de la Conectividad Resumen: Quienes practican la conservación han reconocido durante mucho tiempo que la conectividad ecológica es una prioridad mundial para la preservación de la biodiversidad y el funcionamiento del * email: brett@csp-inc.org Article impact statement: Uses of circuit theory to understand connectivity have had a durable and global impact on conservation science and practice.

Alternative futures analysis can inform community decisions regarding land and water use. We conducted an alternative futures analysis in the Willamette River Basin in western Oregon. Based on detailed input from local stakeholders, three alternative future landscapes for the year 2050 were created and compared to present‐day (circa 1990) and historical (pre‐EuroAmerican settlement) landscapes. We evaluated the likely effects of these landscape changes on four endpoints: water availability, Willamette River, stream condition, and terrestrial wildlife. All three futures assume a doubling of the 1990 human population by 2050. The Plan Trend 2050 scenario assumes current policies and trends continue. Because Oregon has several conservation‐oriented policies in place, landscape changes and projected environmental effects associated with this scenario were surprisingly small (most ≤10% change relative to 1990). The scenario did, however, engender a debate among stakeholders about the reasonableness of assuming that existing policies would be implemented exactly as written if no further policy actions were taken. The Development 2050 scenario reflects a loosening of current policies, more market‐oriented approach, as proposed by some stakeholders. Estimated effects of this scenario include loss of 24% of prime farmland; 39% more wildlife species would lose habitat than gain habitat relative to the 1990 landscape. Projected effects on aquatic biota were less severe, primarily because many of the land use changes involved conversion of agricultural lands into urban or rural development, both of which adversely impact streams. Finally, Conservation 2050 assumes that ecosystem protection and restoration are given higher priority, although still within the bounds of what stakeholders considered plausible. In response, most ecological indicators (both terrestrial and aquatic) recovered 20–70% of the losses sustained since EuroAmerican settlement. The one exception is water availability. Water consumed for out‐of‐stream uses increased under all three future scenarios (by 40–60%), with accompanying decreases in stream flow. Although the conservation measures incorporated into Conservation 2050 moderated the increase in consumption, they were not sufficient to reverse the trend. Results from these analyses have been actively discussed by stakeholder groups charged with developing a vision for the basin's future and a basin‐wide restoration strategy.

Current reserve selection algorithms have difficulty evaluating connectivity and other factors necessary to conserve wide‐ranging species in developing landscapes. Conversely, population viability analyses may incorporate detailed demographic data, but often lack sufficient spatial detail or are limited to too few taxa to be relevant to regional conservation plans. We developed a regional conservation plan for mammalian carnivores in the Rocky Mountain region using both a reserve selection algorithm (SITES) and a spatially explicit population model (PATCH). The spatially explicit population model informed reserve selection and network design by producing data on the locations of population sources, the degree of threat to those areas from landscape change, the existence of thresholds to population viability as the size of the reserve network increased, and the effect of linkage areas on population persistence. A 15% regional decline in carrying capacity for large carnivores was predicted within 25 years if no addition to protected areas occurred. Increasing the percentage of the region in reserves from the current 17.2% to 36.4% would result in a 1–4% increase over current carrying capacity, despite the effects of landscape change. The population model identified linkage areas that were not chosen by the reserve selection algorithm, but whose protection strongly affected population viability. A reserve network based on carnivore conservation goals incidentally protected 76% of ecosystem types, but was poor at capturing localized rare species. Although it is unlikely that planning for focal species requirements alone will capture all facets of biodiversity, when used in combination with other planning foci, it may help to forestall the effects of loss of connectivity on a larger group of threatened species and ecosystems. A better integration of current reserve selection tools and spatial simulation models should produce reserve designs that are simultaneously biologically realistic and taxonomically inclusive.

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Mammalian carnivores are increasingly the focus of reintroduction attempts in areas from which they have been extirpated by historic persecution. We used static and dynamic spatial models to evaluate whether a proposed wolf reintroduction to the southern Rocky Mountain region ( U.S.A ) would advance recovery by increasing species distribution beyond what might be expected through natural range expansion. We used multiple logistic regression to develop a resource‐selection function relating wolf distribution in the Greater Yellowstone region with regional‐scale habitat variables. We also used a spatially explicit population model to predict wolf distribution and viability at several potential reintroduction sites within the region under current conditions and under two contrasting predictions of future landscape change. Areas of the southern Rocky Mountains with resource‐selection‐function values similar to those of currently inhabited areas in Yellowstone could potentially support>1000 wolves, 40% within protected areas and 47% on unprotected public lands. The dynamic model predicted similar distribution under current conditions but suggested that development trends over 25 years may result in the loss of one of four potential regional subpopulations and increased isolation of the remaining areas. The reduction in carrying capacity due to landscape change ranged from 49% to 66%, depending on assumptions about road development on public lands. Although much of the wolf population occurs outside core protected areas, these areas remain the key to the persistence of subpopulations. Although the dynamic model's sensitivity to dispersal parameters made it difficult to predict the probability of natural recolonization from distant sources, it suggested that an active reintroduction to two sites within the region may be necessary to ensure low extinction probability. Social carnivores such as the wolf, which often require larger territories than solitary species of similar size, may be more vulnerable to environmental stochasticity and landscape fragmentation than their vagility and fecundity would suggest.

To conserve biological diversity, protected-area networks must be based not only on current species distributions but also on the landscape's long-term capacity to support populations. We used spatially explicit population models requiring detailed habitat and demographic data to evaluate the ability of existing park systems in the Rocky Mountain region (U.S.A. and Canada) to sustain populations of mammalian carnivores. Predicted patterns of extirpation agreed with those from logistic-regression models based only on park size and connectedness (or isolation) for the grizzly bear (Ursus arctos) in developed landscapes (northern U.S. Rocky Mountains) and semideveloped landscapes (southern Canadian Rocky Mountains). The area-isolation model performed poorly where the landscape matrix contained large amounts of suitable habitat (northern Canadian Rocky Mountains). Park area and connectedness were poor predictors of gray wolf (Canis lupus) occurrence because of this species' broader-scale range dynamics and greater ability to inhabit the landscape matrix. A doubling of park area corresponded to a 47% and 57% increase in projected grizzly bear population persistence in developed and semideveloped landscapes, respectively. A doubling of a park's connectedness index corresponded to a 81% and 350% increase in population persistence in developed and semideveloped landscapes, respectively, suggesting that conservation planning to enhance connectivity may be most effective in the earliest stages of landscape degradation. The park area and connectivity required for population persistence increased as the landscape matrix became more hostile, implying that the relatively small combined area of parks in the boreal forest and other undeveloped regions may fall below the threshold for species persistence if parks become habitat islands. Loss of carnivores from boreal landscapes could further reduce the viability of temperate populations occupying refugia at the southern range margin. Spatially realistic population models may be more informative than simpler patch-matrix models in predicting the effects of landscape change on population viability across a continuum of landscape degradation.Resumen: Para conservar la diversidad biológica, las redes deáreas protegidas deben basarse no solo en la distribución actual de especies sino también en la capacidad a largo plazo del paisaje para soportar poblaciones. Utilizamos modelos espacialmente explícitos, que requieren de datos demográficos y de hábitat detallados, para evaluar la habilidad de los sistemas de parques existentes en la región de las Montañas Rocallosas (E. U.A./Canadá) para sostener poblaciones de mamíferos carnívoros. Los patrones de extirpación predichos coincidieron con los modelos de regresión logística basados sólo en el tamaño y conectividad (o aislamiento) del parque obtenidos para oso grizzli (Ursus arctos) en paisajes desarrollados (norte de Montañas Rocallosas en E.U.A.) y semi-desarrollados (sur de Montañas Rocallosas Canadienses). El modeloárea-aislamiento fu...

We used a spatially explicit population model of wolves (Canis