Landscape Ecol (2007) 22:1–3 DOI 10.1007/s10980-007-9163-x
PREFACE
Why history matters in landscape ecology Jeanine M. Rhemtulla Æ David J. Mladenoff
Received: 27 August 2007 / Accepted: 29 August 2007 / Published online: 12 September 2007 Ó Springer Science+Business Media B.V. 2007
The role of history in shaping the structure and functioning of ecosystems has become increasingly apparent to ecologists over the past decade (Christensen 1989; Foster et al. 2003). The legacy of past events—natural and anthropogenic—can reverberate through ecosystems for hundreds to thousands of years (Dupouey et al. 2002). These legacies often become drivers of ecosystem functioning otherwise hidden from a static view of landscapes in the present. While many of us realize that pervasive changes mean that the past cannot be a blueprint for the future, reconstructing these historical patterns and processes is key to understanding how present conditions came about, how ecosystems function, and in contributing to wise management and restoration decisions. To reconstruct past conditions and uncover these hidden ecosystem drivers, ecologists are increasingly making use of various kinds of historical data
J. M. Rhemtulla D. J. Mladenoff Department of Forest Ecology and Management, University of Wisconsin-Madison, Madison, WI 53706, USA Present Address: J. M. Rhemtulla (&) Department of Geography, McGill University, H3A 2K6 Montreal, QC, Canada e-mail:
[email protected]
sources, from pollen and tree rings to old land survey records, written accounts, cadastral maps, aerial photographs, and oral interviews (Egan and Howell 2001). In this special issue, we have drawn together a group of papers that represent some of the most interesting work currently being done in this area. In keeping with the focus of this journal, most of the papers take a landscape approach to the theme by making spatial use of the historical data. While some might argue that, by definition, historical ecology must include an examination of the human history of a system (Crumley 1994), we prefer to take a broader perspective, and would include any research that examines the changes in and interactions among ecosystem patterns and processes through time: the history of an ecosystem. Such changes more often than not include anthropogenic effects, but these do not always need to be explicitly considered. As such, this special issue ranges from papers that focus predominantly on the biophysical history of an ecosystem to those that reconstruct to varying degrees the historical interplay between human and natural drivers of change. The issue begins with a manuscript by Hessburg et al. that re-examines the fire history of mixed conifer forests in the northwestern USA. Using historical pattern to infer historical process, the authors use old aerial photographs to reconstruct pre-management fire severity. They find less evidence of low-severity fire regimes than expected, and
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suggest that variable severity fire, including standreplacing fires, were more important in these forests than previously thought. The next three papers offer different perspectives on the historical ecology of Wisconsin, USA. Hotchkiss et al. begin with an innovative approach that combines paleoecological techniques with historical land survey records to examine how vegetation communities and fire regimes in the northwestern Wisconsin sand plain have responded to changes in climate over the past 1200 years. The study highlights the importance of long time scales in ecology. While historical land survey records are often used as baseline data for restoration projects, Hotchkiss and colleagues show just how dynamic vegetation can be through time, especially in disturbance prone landscapes sensitive to drought and fire. They suggest that some vegetation communities at the time of Euro-American settlement in Wisconsin may in fact have been transitory, rather than representative of longer-term conditions. Grossmann et al., working in the same sand plain but focusing on a narrower time period, examine how the forest landscape mosaic has responded to changes in natural and anthropogenic disturbance regimes since the 1930s. Their results indicate that intermediate density woodlands and savannas are highly transitory and have declined in extent, while closed forest types have increased, leading overall to a simplification of the landscape. Finally, starting from the same land survey records as Hotchkiss et al, Rhemtulla et al. reconstruct changes in regional land-cover patterns across Wisconsin following the arrival of EuroAmerican settlers. Although evidence in other regions of eastern North America suggest that logging and agricultural clearing were followed by farm abandonment and subsequent forest recovery (Hall et al. 2002), this study shows that historical land-use patterns continue to dominate in the present, with relatively little recovery in broadscale land cover since the height of the agricultural era in the 1930s. Next, from a more conceptual perspective, Burgi and colleagues describe the three main objectives of historical ecology, as they see them. They illustrate the paper with a fascinating case study on leaf litter
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collection, a largely forgotten and poorly documented traditional practice with a long history in European forests. The authors argue that such traditional practices may have had large impacts on forest ecosystem functioning, and that restoring these practices may thus be critical to maintaining the cultural landscape and associated biodiversity. By combining oral history interviews with documentary sources, aerial photographs, and satellite images, Arce examines sixty years of change in a cultural landscape in the Peruvian Amazon. His analysis shows that the trajectories of change are not linear, but in fact reflect a complex and changing series of social, economic, and natural factors. Finally, using an impressively broad array of historical sources, and careful triangulation and accuracy assessment techniques, Grossinger and colleagues reconstruct the historical ecology of an urban California ecosystem—Silicon Valley. Although restoration might seem futile in such an urban setting, the results highlight a number of unrecognized restoration opportunities and also reveal that some riparian habitat considered to be degraded is in fact a remnant of a historically important vegetation community. Taken together, the papers in this special issue present an overview of the insights available to landscape ecologists through the lens of history. Given the wide array of sources and methods available, and the importance of historical processes in controlling contemporary functioning, we hope that they will stimulate further discussion of the topic. Acknowledgements We thank our colleagues, the authors and speakers in a special symposium at the US IALE meeting in April, 2006 in San Diego, and the meeting organizers who made our symposium possible. We also want to thank Jingle Wu, Editor-in-Chief of Landscape Ecology, for encouraging this special issue, and for handling outside review of those papers on which we appear as an author. We also thank the many colleagues who reviewed the manuscripts.
References Christensen NL (1989) Landscape history and ecological change. J For Hist 33:116–124 Crumley CL (1994) Historical ecology: a multidimensional ecological orientation. In: Crumley CL (ed) Historical ecology: cultural knowledge and changing landscapes. School of American Research Press, Santa Fe, New Mexico
Landscape Ecol (2007) 22:1–3 Dupouey JL, Dambrine E, Laffite JD, Moares C (2002) Irreversible impact of past land use on forest soils and biodiversity. Ecology 83:2978–2984 Egan D, Howell EA (2001) The historical ecology handbook: a restorationist’s guide to reference ecosystems. Island Press, Washington
3 Foster D, Swanson F, Aber J, Burke I, Brokaw N, Tilman D, Knapp A (2003) The importance of land-use legacies to ecology and conservation. BioScience 53:77–88 Hall B, Motzkin G, Foster DR, Syfert M, Burk J (2002) Three hundred years of forest and land-use change in Massachusetts, USA. J Biogeogr 29:1319–1335
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