Abstract Green spaces in urban areas—like remnant habitat, parks, constructed wetlands, and street trees—supply multiple benefits. Many studies show green spaces in and near urban areas play important roles harbouring biodiversity and promoting human well‐being. On the other hand, evidence suggests that greater human population density enables compact, low‐carbon cities that spare habitat conversion at the fringes of expanding urban areas, while also allowing more walkable and livable cities. How then can urban areas have abundant green spaces as well as density? In this paper, we review the empirical evidence for the relationships between urban density, nature, and sustainability. We also present a quantitative analysis of data on urban tree canopy cover and open space for United States large urbanized areas, as well as an analysis of non‐US Functional Urban Areas in OECD countries. We found that there is a negative correlation between population density and these green spaces. For Functional Urban Areas in the OECD, a 10% increase in density is associated with a 2.9% decline in tree cover. We argue that there are competing trade‐offs between the benefits of density for sustainability and the benefits of nature for human well‐being. Planners must decide an appropriate density by choosing where to be on this trade‐off curve, taking into account city‐specific urban planning goals and context. However, while the negative correlation between population density and tree cover is modest at the level of US urbanized areas (R2 = 0.22), it is weak at the US Census block level (R2 = 0.05), showing that there are significant brightspots, neighbourhoods that manage to have more tree canopy than would be expected based upon their level of density. We then describe techniques for how urban planners and designers can create more brightspots, identifying a typology of urban forms and listing green interventions appropriate for each form. We also analyse policies that enable these green interventions illustrating them with the case studies of Curitiba and Singapore. We conclude that while there are tensions between density and urban green spaces, an urban world that is both green and dense is possible, if society chooses to take advantage of the available green interventions and create it. Read the free Plain Language Summary for this article on the Journal blog.

Abstract Conserving urban biodiversity will rely on updating our planning paradigms. This work synthesizes urban ecological research and identifies seven elements—patch size, connections, matrix quality, habitat diversity, native vegetation, special resources, and stewardship and management—as key factors associated with urban biodiversity. It then distils these findings into a science-based framework for building urban biodiversity. Beyond providing a framework, it demonstrates how to use this approach to integrate conservation into urban planning and provides an example where this framework has been applied. Such a landscape ecological approach will provide a science-driven approach to advance urban biodiversity and promote equitable access to urban nature.

Cities are both embedded within and ecologically linked to their surrounding landscapes. Although urbanization poses a substantial threat to biodiversity, cities also support many species, some of which have larger populations, faster growth rates, and higher productivity in cities than outside of them. Despite this fact, surprisingly little attention has been paid to the potentially beneficial links between cities and their surroundings. We identify five pathways by which cities can benefit regional ecosystems by releasing species from threats in the larger landscape, increasing regional habitat heterogeneity and genetic diversity, acting as migratory stopovers, preadapting species to climate change, and enhancing public engagement and environmental stewardship. Increasing recognition of these pathways could help cities identify effective strategies for supporting regional biodiversity conservation and could provide a science-based platform for incorporating biodiversity alongside other urban greening goals.

In response to the widely recognized negative impacts of urbanization on biodiversity, many cities are reimagining urban design to provide better biodiversity support. Some cities have developed urban biodiversity plans, primarily focused on improving biodiversity support and ecosystem function within the built environment through habitat restoration and other types of urban greening projects. The biophilic cities movement seeks to reframe nature as essential infrastructure for cities, seamlessly integrating city and nature to provide abundant, accessible nature for all residents and corresponding health and well-being outcomes. Urban biodiversity planning and biophilic cities have significant synergies in their goals and the means necessary to achieve them. In this paper, we identify three key ways by which the urban biodiversity planning process can support biophilic cities objectives: engaging the local community; identifying science-based, quantitative goals; and setting priorities for action. Urban biodiversity planning provides evidence-based guidance, tools, and techniques needed to design locally appropriate, pragmatic habitat enhancements that support biodiversity, ecological health, and human health and well-being. Developing these multi-functional, multi-benefit strategies that increase the abundance of biodiverse nature in cities has the potential at the same time to deepen and enrich our biophilic experience in daily life.

Investing in nature and nature-based solutions is an important pathway to address the current ecological crisis. The loss of biodiversity, with around one million animal and plant species threatened with extinction, is putting at risk our economies, livelihoods, food security, health, and quality of life worldwide. Diverse and innovative measures are needed to reverse this decline and to restore healthy ecosystems. The magnitude of the challenge calls for the collaboration and contribution of all actors, including non-state actors, such as businesses, local authorities, civil society organisations, and individual citizens. Sports and urban biodiversity identifies the opportunities for sports federations and sport venue owners and operators to develop the seven elements essential for supporting nature in cities. Case studies from Europe, North America, Australia and South Africa capture the biodiversity actions taken by a variety of sports, from Olympic city planning to local projects at stadiums and practice facilities. These examples also reveal ways in which improvements to urban biodiversity elements can offer a better sporting experience for event participants and spectators.

Ecological resilience is a powerful heuristic for ecosystem management in the context of rapid environmental change. Significant efforts are underway to improve the resilience of biodiversity and ecological function to extreme events and directional change across all types of landscapes, from intact natural systems to highly modified landscapes such as cities and agricultural regions. However, identifying management strategies likely to promote ecological resilience remains a challenge. In this article, we present seven core dimensions to guide long-term and large-scale resilience planning in highly modified landscapes, with the objective of providing a structure and shared vocabulary for recognizing opportunities and actions likely to increase resilience across the whole landscape. We illustrate application of our approach to landscape-scale ecosystem management through case studies from two highly modified California landscapes, Silicon Valley and the Sacramento–San Joaquin Delta. We propose that resilience-based management is best implemented at large spatial scales and through collaborative, cross-sector partnerships.

American Journal of BotanyVolume 104, Issue 5 p. 645-648 On the Nature of ThingFree Access Toward principles of historical ecology Erin Beller, Corresponding Author Erin Beller [email protected] Resilient Landscapes Program, San Francisco Estuary Institute, 4911 Central Avenue, Richmond, California 94804 USA Department of Geography, University of California Berkeley, 565 McCone Hall, Berkeley, California 94720 USAAuthor for correspondence (e-mail: [email protected])Search for more papers by this authorLoren McClenachan, Loren McClenachan Environmental Studies, Colby College, 5351 Mayflower Hill, Waterville, Maine 04901 USASearch for more papers by this authorAndrew Trant, Andrew Trant School of Environment, Resources and Sustainability, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3GSearch for more papers by this authorEric W. Sanderson, Eric W. Sanderson Wildlife Conservation Society Global Conservation Programs, 2300 Southern Blvd, Bronx, New York 10460 USASearch for more papers by this authorJeanine Rhemtulla, Jeanine Rhemtulla Forest and Conservation Sciences, University of British Columbia, 3609-2424 Main Mall, Vancouver, British Columbia, Canada V6T 1Z4Search for more papers by this authorAnita Guerrini, Anita Guerrini School of History, Philosophy, and Religion, Oregon State University, 322 Milam Hall, Corvallis, Oregon 97331 USASearch for more papers by this authorRobin Grossinger, Robin Grossinger Resilient Landscapes Program, San Francisco Estuary Institute, 4911 Central Avenue, Richmond, California 94804 USASearch for more papers by this authorEric Higgs, Eric Higgs School of Environmental Studies, University of Victoria, Room 205, House 4, Victoria, British Columbia, Canada V8P 5C2Search for more papers by this author Erin Beller, Corresponding Author Erin Beller [email protected] Resilient Landscapes Program, San Francisco Estuary Institute, 4911 Central Avenue, Richmond, California 94804 USA Department of Geography, University of California Berkeley, 565 McCone Hall, Berkeley, California 94720 USAAuthor for correspondence (e-mail: [email protected])Search for more papers by this authorLoren McClenachan, Loren McClenachan Environmental Studies, Colby College, 5351 Mayflower Hill, Waterville, Maine 04901 USASearch for more papers by this authorAndrew Trant, Andrew Trant School of Environment, Resources and Sustainability, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada N2L 3GSearch for more papers by this authorEric W. Sanderson, Eric W. Sanderson Wildlife Conservation Society Global Conservation Programs, 2300 Southern Blvd, Bronx, New York 10460 USASearch for more papers by this authorJeanine Rhemtulla, Jeanine Rhemtulla Forest and Conservation Sciences, University of British Columbia, 3609-2424 Main Mall, Vancouver, British Columbia, Canada V6T 1Z4Search for more papers by this authorAnita Guerrini, Anita Guerrini School of History, Philosophy, and Religion, Oregon State University, 322 Milam Hall, Corvallis, Oregon 97331 USASearch for more papers by this authorRobin Grossinger, Robin Grossinger Resilient Landscapes Program, San Francisco Estuary Institute, 4911 Central Avenue, Richmond, California 94804 USASearch for more papers by this authorEric Higgs, Eric Higgs School of Environmental Studies, University of Victoria, Room 205, House 4, Victoria, British Columbia, Canada V8P 5C2Search for more papers by this author First published: 17 May 2017 https://doi.org/10.3732/ajb.1700070Citations: 24 Freely available online through the AJB open access option. AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Rising temperatures and sea levels, biological homogenization and biodiversity loss, habitat fragmentation, and other environmental changes are dramatically reshaping landscapes across the globe. In this context, understanding the patterns, drivers, and consequences of these changes has become one of the central challenges facing environmental scientists and managers today. Yet to do so requires a long-term perspective on environmental systems that predates many of the accelerated anthropogenic impacts of the recent past. How, then, can we understand these changes in the context of decade- and century-scale ecosystem trajectories and human history? What was the structure, function, and dynamics of ecosystems like before these changes? And how have people shaped these systems over time? These questions are the domain of historical ecology. Historical ecology is the study of nature over time, often (though not necessarily) with a focus on human–environment interactions and the causes and consequences of changes caused by human actions in the recent past (Crumley, 2003; Rhemtulla and Mladenoff, 2007). The field includes both researchers who wish to document ecological patterns and dynamics in the recent past using historical methods, as well as those interested in historicizing ecology—that is, understanding the relationships between nature and human culture over time (cf. Szabo [2014] for a detailed treatment). It draws on a broad range of qualitative and quantitative sources that vary in temporal and spatial coverage, require creative and thoughtful methods to synthesize and interpret, and are often integrated in ways that cross traditional disciplinary boundaries (Fig. 1). Data include traditional archival sources such as written documents, maps, oral histories, land surveys, landscape views and photography, along with biological and physical data such as sediment and pollen records, tree rings, species lists, and habitat relationships (Swetnam et al., 1999; Egan and Howell, 2001; Vellend et al., 2013). While relying on data from the past, historical ecology is an inherently future-oriented discipline given its emphasis on temporal dynamics and change trajectories (Higgs et al., 2014). It provides vivid narratives of past landscapes and change that are of interest to specialists and nonspecialists alike (e.g., Sanderson, 2009; Grossinger, 2012). Figure 1Open in figure viewerPowerPoint Historical ecology draws on a broad range of archival and biophysical sources that provide windows into the nature of past ecosystems and landscapes. A wide array of material is available for recent decades; artifacts, traditional ecological knowledge, and natural archives such as pollen cores shed light on earlier eras. ya = years ago. Historical ecology is part of a long tradition of understanding relationships between humans and environmental change and shares strong topical and methodological affinities with paleoecology, environmental history, and historical geography. It is similar to "temporal ecology" (sensu Wolkovich et al., 2014), though temporal ecology relies more on time series data, rather than integrating a broad array of data types within their historical context. Historical ecology has much in common with landscape and restoration ecology, ecological subfields that emphasize spatial patterns and processes, human–environment interactions, and temporal dynamism. As a field, historical ecology largely operates at the intersection of ecology, history, anthropology, and geography, using tools and techniques from all four disciplines to help people conceive of what populations, communities, ecosystems, and landscapes existed in the past and how they have changed over time (Szabó, 2014). It also relies heavily on the history of science, since interpretation of often fragmentary, qualitative, and idiosyncratic historical data requires an understanding of the historical, scientific, and cultural contexts in which past records and scientific data were produced (Raby, 2015). Studies cast a broad net of topics of interest, from traditional ecological questions such as documenting population abundance and community composition, habitat distribution, and ecological processes and functions, to geographic questions such as changes in geophysical patterns and processes (e.g., groundwater dynamics, stream morphology) and socioecological questions such as understanding traditional landscape management and setting goals and objectives for ecological restoration. As a result, historical ecology research is highly interdisciplinary and not restricted to a subfield of ecological science; rather, practitioners are spread across the humanities, social sciences, and natural sciences. While this interdisciplinarity is a source of strength, it has also complicated the consolidation of historical ecology into a unified field. Historical ecology has developed rapidly over the past two decades, especially with the adoption of geographic information systems, widespread digitization of historical documents and maps, and increased concern about the state of future landscapes. Yet unlike other related fields, historical ecology has no degree programs, no conference for its practitioners, and no journals dedicated to its study and advancement. Efforts to bring together scholars of historical ecology have largely occurred to date through topical conferences (e.g., Oceans Past) and at special sessions at conferences for other fields (e.g., at the American Association of Geographers, the American Society for Environmental History, International Association for Landscape Ecology, or the Ecological Society of America); similarly, historical ecological research is currently published in a broad variety of ecological, geographic, historical, and anthropological journals. While this certainly reflects the applicability of historical ecology to a wide range of disciplines, it may also limit potential advancements in the field that could be facilitated by dedicated venues. More importantly, perhaps, to date there has been no attempt at defining principles or a theory of historical ecology, despite the rapidly growing quantity of research in the field. We contend that the time is right to develop a unified framework for understanding temporal change in complex social–environmental systems. Here we provide background on the value of historical ecology and outline initial principles of historical ecology, with a view toward consolidating existing approaches. What does historical ecology contribute to the study of ecology? Historical ecology can provide novel insights across a uniquely broad range of ecological scales, from population to landscape. At the population level, historical ecology can address questions about long-term changes to population size, density, distribution, and structure. For example, 19th century fishing logs from the Scotian Shelf suggested biomass of Atlantic cod (Gadus morhua) was two orders of magnitude greater than fisheries scientists observed it to be in the 20th century, which changed views of the potential productivity of this system (Rosenberg et al., 2005). At the community level, historical ecology can address questions of how past changes in species dominance have contributed to observed changes in community stability. For example, in Caribbean coral reefs, a phase shift to algal-dominated systems was observed in the 1980s, with the proximate cause diagnosed as a disease in the most abundant herbivore, the spiny sea urchin (Diadema antillarum). However, historical analyses revealed that overfishing over centuries reduced the abundance of other herbivores, facilitating the rapid transition (McClenachan et al., 2015). At the ecosystem level, historical ecology can provide insight into long-term changes in resource-use patterns that can affect nutrient availability and ecosystem processes. For example, indigenous peoples of the Pacific Northwest have been harvesting shellfish for millennia, resulting in the movement of significant amounts of marine-derived nutrients into the nearby terrestrial ecosystem and creating legacies of enhanced forest productivity that persist today (Trant et al., 2016). At the landscape level, historical ecology can assess change and persistence in habitat type extent and distribution over time and link observed patterns to geophysical characteristics. For example, an analysis of land cover change along a large California river documented a formerly heterogeneous mosaic of riparian vegetation communities (including willow–cottonwood forested wetlands and xeric scrublands) linked to local variations in dry-season surface flow, then this analysis was used to identify priority locations with suitable conditions for riparian restoration (Beller et al., 2016). Toward principles of historical ecology By casting a wide net across space and time and integrating across disciplines, historical ecology is uniquely situated to provide novel insights into complex system dynamics and change in the Anthropocene. We argue that historical ecology's uniquely integrated approach and ability to provide novel insights across all scales of ecology make it more than a tool to "simply provide a means of extending the time frame" of ecological research (e.g., Vellend et al., 2013). Instead, shared general concepts and theories unite the discipline as a framework for research, analysis, and application. Looking forward, we identify the need to develop a conceptual framework that clearly defines the topical, spatiotemporal, and methodological scope of historical ecology along with widely accepted principles to standardize methods and sources, unite disparate studies, and maximize the application of findings (Fig. 2). We see a parallel evolution to that of landscape ecology, for which general principles coalesced in the 1990s (Wiens, 1992; Forman, 1995), or that of geographic information science (GIS) over the past two decades as emphasis has shifted from GIS as a "tool" or "system" to a "science" (Goodchild, 2010). Figure 2Open in figure viewerPowerPoint Conceptual framework illustrating the scope of historical ecology. Historical ecology encompasses historical ecosystem characteristics (bottom right), biophysical setting and processes (bottom left), and the interaction of humans with their environment (top); time (both past states and change) is implicit across all. So what might historical ecology principles look like? They might address human–environment interactions and feedbacks, define the scope of "history" in the context of ecological change, delineate the spatial and temporal scale and resolution of historical ecology studies and temporal continuity, address the importance of place, address theories of ecological and landscape transformation and disturbance, and reflect on its application to current and future ecosystems, to name a few. These principles can draw inspiration from existing ecological principles, such as principles of landscape change and scale from landscape ecology (Forman, 1995) or of land-use management (Dale et al., 2000). Principles could range from the extremely simple (e.g., "Ecosystems change through time" or "Humans are important, often dominant, drivers of disturbance") to complex concepts that address historical continuity and ecological memory (e.g., "Ecological landscape patterns at a given time are reflective of landscape and land-use history, setting, and biological interactions"). In developing principles of historical ecology, the challenge will be how to retain the "big tent" flexibility that historical ecology currently offers—that accommodates multiple perspectives, disciplines, and approaches—while articulating and honing a shared conceptual framework. Such principles could provide a backbone for subsequent historical ecology research, education, and application, setting the stage for helping all of us anticipate and manage for ongoing and future environmental change. ACKNOWLEDGEMENTS The authors thank three anonymous reviewers and Editor-in-Chief Pamela Diggle for their helpful comments on an earlier version of this manuscript. LITERATURE CITED Beller, E. E., P. Downs, R. M. Grossinger, B. K. Orr, and M. N. Salomon. 2016. From past patterns to future potential: Using historical ecology to inform river restoration for an intermittent California river. Landscape Ecology 31: 581– 600. Crumley, C. L. 2003. Historical ecology: Integrated thinking at multiple temporal and spatial scales. In World System History and Global Environmental Change, 2003, Lund University, Lund, Sweden. Available at http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.554.2791&rep=rep1&type=pdf. Dale, V. H., S. Brown, R. A. Haeuber, N. T. Hobbs, N. Huntly, R. J. Naiman, W. E. Riebsame et al. 2000. Ecological principles and guidelines for managing the use of land. Ecological Applications 10: 639– 670. Egan, D., and E. A. Howell. 2001. The historical ecology handbook: A restorationist's guide to reference ecosystems. Island Press, Washington D.C., USA. Forman, R. T. 1995. Some general principles of landscape and regional ecology. Landscape Ecology 10: 133– 142. Goodchild, M. F. 2010. Twenty years of progress: GIScience in 2010. Journal of Spatial Information Science 1: 3– 20. Grossinger, R. 2012. Napa Valley historical ecology atlas: Exploring a hidden landscape of transformation and resilience. University of California Press, Berkeley, California, USA. Higgs, E., D. A. Falk, A. Guerrini, M. Hall, J. Harris, R. J. Hobbs, and W. Throop. 2014. The changing role of history in restoration ecology. Frontiers in Ecology and the Environment 12: 499– 506. McClenachan, L., A. B. Cooper, M. G. McKenzie, and J. A. Drew. 2015. The importance of surprising results and best practices in historical ecology. BioScience 65: 932– 939. Raby, M. 2015. Ark and archive: Making a place for long-term research on Barro Colorado Island, Panama. Isis 106: 798– 824. Rhemtulla, J. M., and D. J. Mladenoff. 2007. Why history matters in landscape ecology. Landscape Ecology 22: 1– 3. Rosenberg, A. A., W. J. Bolster, K. E. Alexander, W. B. Leavenworth, A. B. Cooper, and M. G. McKenzie. 2005. The history of ocean resources: Modeling cod biomass using historical records. Frontiers in Ecology and the Environment 3: 84– 90. Sanderson, E. W. 2009. Mannahatta: A natural history of New York City. Abrams, New York, New York, USA. Swetnam, T. W., C. D. Allen, and J. L. Betancourt. 1999. Applied historical ecology: Using the past to manage for the future. Ecological Applications 9: 1189– 1206. Szabó, P. 2014. Historical ecology: Past, present and future. Biological Reviews of the Cambridge Philosophical Society 90: 997– 1014. Trant, A., W. Nijland, K. Hoffman, D. L. Mathews, D. McLaren, T. A. Nelson, and B. M. Starzomski. 2016. Intertidal resource use over millennia enhances forest productivity. Nature Communications 7: 12491. Vellend, M., C. D. Brown, H. M. Kharouba, J. L. McCune, and I. H. Myers-Smith. 2013. Historical ecology: Using unconventional data sources to test for effects of global environmental change. American Journal of Botany 100: 1294– 1305. Wiens, J. 1992. What is landscape ecology, really? Landscape Ecology 7: 149– 150. Wolkovich, E. M., B. I. Cook, K. K. McLauchlan, and T. J. Davies. 2014. Temporal ecology in the Anthropocene. Ecology Letters 17: 1365– 1379. Citing Literature Volume104, Issue5May 2017Pages 645-648 This article also appears in:The "On the Nature of Things" Essays: New Ideas and Directions in Botany FiguresReferencesRelatedInformation

doi: http://dx.doi.org/10.15447/sfews.2016v14iss3art1To evaluate the role of restoration in the recovery of the Delta ecosystem, we need to have clear targets and performance measures that directly assess ecosystem function. Primary production is a crucial ecosystem process, which directly limits the quality and quantity of food available for secondary consumers such as invertebrates and fish. The Delta has a low rate of primary production, but it is unclear whether this was always the case. Recent analyses from the Historical Ecology Team and Delta Landscapes Project provide quantitative comparisons of the areal extent of 14 habitat types in the modern Delta versus the historical Delta (pre-1850). Here we describe an approach for using these metrics of land use change to: (1) produce the first quantitative estimates of how Delta primary production and the relative contributions from five different producer groups have been altered by large-scale drainage and conversion to agriculture; (2) convert these production estimates into a common currency so the contributions of each producer group reflect their food quality and efficiency of transfer to consumers; and (3) use simple models to discover how tidal exchange between marshes and open water influences primary production and its consumption. Application of this approach could inform Delta management in two ways. First, it would provide a quantitative estimate of how large-scale conversion to agriculture has altered the Delta's capacity to produce food for native biota. Second, it would provide restoration practitioners with a new approach—based on ecosystem function—to evaluate the success of restoration projects and gauge the trajectory of ecological recovery in the Delta region.

doi: http://dx.doi.org/10.15447/sfews.2016v14iss2art9 What happens at one place in a landscape influences and is influenced by what happens in other places. Consequently, management and restoration that focus on individual places may fail to recognize and incorporate interactions across entire landscapes. The science of landscape ecology, which emphasizes the interplay of landscape structure, function, and change at multiple scales, offers a perspective that can integrate the spatial relationships of ecological processes and the functional interconnections of land and water in the Delta. Although the Delta is one of the most studied estuaries in the world, applications of landscape science have been limited. We describe why it is important to incorporate landscape science into management and restoration, emphasizing how Delta landscapes have changed over the past centuries. The land–water linkages of the past have been broken, waterways have been over-connected, and hard boundaries have replaced the gradual and dynamic transitions among landscape patches. The contemporary landscape also has new, novel assemblages of species and stressors that were not there in the past. This historical perspective indicates how knowledge of past landscape functions can contribute to the restoration and management of contemporary landscapes. We illustrate these points with case studies of inundation dynamics and riparian woodlands, and use a third example to describe a landscape approach to restoration. We propose that science that encompasses the multiple, interacting components of functional landscapes in the Delta will foster resilient and enduring restoration and management outcomes that benefit both people and wildlife. We suggest several ways of moving landscape science to the forefront of management and restoration in the Delta.

Context Effective river restoration requires understanding a system’s potential to support desired functions. This can be challenging to discern in the modern landscape, where natural complexity and heterogeneity are often heavily suppressed or modified. Historical analysis is therefore a valuable tool to provide the long-term perspective on riverine patterns, processes, and ecosystem change needed to set appropriate environmental management goals and strategies. Objective In this study, we reconstructed historical (early 1800s) riparian conditions, river corridor extent, and dry-season flow on the lower Santa Clara River in southern California, with the goal of using this enhanced understanding to inform restoration and management activities. Method Hundreds of cartographic, textual, and visual accounts were integrated into a GIS database of historical river characteristics. Results We found that the river was characterized by an extremely broad river corridor and a diverse mosaic of riparian communities that varied by reach, from extensive (>100 ha) willow-cottonwood forests to xeric scrublands. Reach-scale ecological heterogeneity was linked to local variations in dry-season water availability, which was in turn underpinned by regional geophysical controls on groundwater and surface flow. Conclusions Although human actions have greatly impacted the river’s extent, baseflow hydrology, and riparian habitats, many ecological attributes persist in more limited form, in large part facilitated by these fundamental hydrogeological controls. By drawing on a heretofore untapped dataset of spatially explicit and long-term environmental data, these findings improve our understanding of the river’s historical and current conditions and allow the derivation of reach-differentiated restoration and management opportunities that take advantage of local potential.