Toward principles of historical ecology

Abstract

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 conse-quences 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 re-cent past. How, then, can we understand these changes in the con-text 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? Th ese questions are the domain of historical ecology. Historical ecology is the study of nature over time, oft en (though not necessarily) with a focus on human–environment interactions and the causes and consequences of changes caused by human ac-tions in the recent past (Crumley, 2003 ; Rhemtulla and Mladenoff , 2007). Th e fi eld includes both researchers who wish to document ecological patterns and dynamics in the recent past using histori-cal 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 oft en 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 photogra-phy, 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 inher-ently 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). Historical ecology is part of a long tradition of understanding relationships between humans and environmental change and shares strong topical and methodological affinities with paleo-ecology, environmental history, and historical geography. It is simi-lar to " temporal ecology " (sensu Wolkovich et al., 2014), though temporal ecology relies more on time series data, rather than inte-grating a broad array of data types within their historical context. Historical ecology has much in common with landscape and resto-ration ecology, ecological subfi elds that emphasize spatial patterns and processes, human–environment interactions, and temporal dynamism. As a fi eld, 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 ex-isted in the past and how they have changed over time (Szabó, 2014). It also relies heavily on the history of science, since inter-pretation of oft en fragmentary, qualitative, and idiosyncratic his-torical data requires an understanding of the historical, scientifi c, and cultural contexts in which past records and scientifi c data were produced (Raby, 2015). Studies cast a broad net of topics of interest, from traditional ecological questions such as document-ing population abundance and community composition, habitat distribution, and ecological processes and functions, to geographic questions such as changes in geophysical patterns and processes 1 Manuscript