Historical Ecology for Conservation Managers


Measuring and Imagining: Exploring Centuries of Australian Landscape Change. The Special 50th Anniversary Issue of the Australian Journal of Botany, Volume 50, Number 4. Bowman, D. M., J. S., and S. L. Farrer, editors. 2002. CSIRO Publishing, Collingswood, Victoria, Australia. 544 pp. $AU75.00. ISSN 0067–1924.

The question of what we are managing for is becoming a dominant theme in sustainable land management and biodiversity conservation. In addition to establishing how to measure and interpret anthropogenic change against natural ecological dynamics, there is increasing recognition that, prior to European colonial expansion, most landscapes were—to varying degrees—cultural, managed by indigenous populations. This raises questions about which point in history current conservation-management objectives are striving to replicate. This realization is particularly pertinent in Australia and North America, where indigenous human populations often were removed from the land and the concepts of terra nullius and, more recently, human-free wilderness came to the fore.

Conservation decisions are made in a complex milieu of political, economic, and social demands and values, as well as in light of ecological considerations. Increasingly, the multidisciplinary nature of conservation management requires input from both the humanities and the sciences, which is reflected in the emerging fields of historical ecology and environmental history. This edited volume provides a very useful and timely review of techniques and issues in these emerging fields, particularly historical ecology, for the 50th Anniversary Issue of the Australian Journal of Botany.

The focus of this volume is a critical examination of techniques available to the researcher of historical ecology for assessing environmental—mainly vegetational—change over time scales of decades to centuries. This is achieved through a meta-analysis of methods used by ecologists studying century-scale landscape change in Australia (by Ian Lunt), and by a series of incisive methodological reviews and case studies. Techniques specifically reviewed or critically assessed in case studies are repeat photography, including the use of archival images; aerial and remote photography; dendrochronology; stable carbon isotopes; and sediment analysis, including palynology and trace-element analysis. Applications of some techniques are nicely demonstrated in four case studies and a meta-analysis, two of which illustrate the limitations of specific techniques in measuring the impact of European settlement on Australian landscapes.

Several themes emerge from these methodological papers. The first is that the extent of anthropogenic change needs to be assessed against a baseline of inherently dynamic natural systems. Dodson and Mooney demonstrate a significant increase in the rate and amplitude of change in sedimentation and vegetation that has been sustained since the European agricultural settlement of southeastern Australia, including a loss of ecological resilience at some sites, against the background dynamics of the fairly stable late-Holocene period. Second is the importance of scale. Three papers that deal with sediment and stable isotope analysis (by Witt, Dodson & Mooney, and Harle et al.) emphasize the constraints of these techniques and the need for high resolution to achieve the spatial precision and accuracy relevant both to local variation and to the history of anthropogenic activity. Third, a recurring theme is the limitations in all of the techniques. Some authors provide very detailed and useful reviews of these. Witt emphasises the need to explore as many lines of investigation as possible, a hallmark of good science and particularly useful in the role of challenging popular myths. The contributing editor inspires the use of imagination (“lateral thinking,” in scientific parlance) to extrapolate between often disparate data points in this historical science. The final theme—which researchers should heed—is the importance of long-term ecological studies in understanding ecological dynamics (emphasized by Lunt). Constraints of funding and researcher continuity usually dictate short-term, place-for-time substitutions. The value of longitudinal studies is demonstrated in the case study by Brown et al., in which an earlier study site revisited after 20 years failed to provide evidence of flux in vegetation structure or floristic boundaries to support a widely accepted successional model.

In addition to the methodological papers, Griffiths contributes a very interesting paper discussing the importance of cultural as well as ecological history in interpretation of anthropogenic landscape change. Understanding of aboriginal and changing European attitudes toward land use, fire, and forest clearance is vital for assessing the relative contributions of humans and nature to major environmental events such as wildfires and droughts. A separate section, comprising two papers, is dedicated to modeling the effects of increased atmospheric carbon dioxide and to the implications of international policy in driving research needs for the quantification of landscape carbon dynamics. An unexpected result is that increased carbon dioxide will result in increased plant growth and counter some of the effects of European settlement.

As expected with a diverse coverage of the topic, there is variation in the degree of comprehensiveness and in the style of the papers in this edited journal volume. Most papers are excellent; only one is less impressive. The preface provides the reader with the overall context and aims of the collection and a synthesis of the major issues that have emerged from the contributed papers. This is rather a loosely organized volume, though, and would have benefited from more cohesive a priori structuring into thematic subsections. The first section, “Reviews and Meta-analyses,” is a mixture of an issues review, a techniques review that uses meta-analysis, four techniques papers, and a meta-analysis case study that deals with contextual issues (Dodson & Mooney). Two of the case studies in the second section examine techniques (Harle et al.) and issues (Brown et al.) not reviewed in the first section. It would be nice to see a separate section at the beginning reviewing both cultural (first paper) and perhaps scientific (new paper) debates about landscape change in Australia. A second section could then include all the techniques papers, including meta-analyses, reviews, and case studies. The final section on carbon dynamics sits well as is.

This anniversary volume provides a valuable and timely review of techniques and issues that will promote scientific rigor in this emerging field of the historical sciences. The contributing editor, David Bowman, and the authors of each paper are well placed in their research fields to review this topic. Political and public awareness and commitment to reversing extensive land degradation and clearance, and mammalian extinction rates that are the highest in the world, are growing in Australia. Bowman (2001) suggests that ecologists learn to harness the power of popular environmental history narratives to promote sustainable land management. Part of this process is using a rigorous scientific approach and methodology to refine ecologically “fit” stories and to promote these over ecologically flawed stories. The power of popular mythology, the fallacy and expense of misguidance in landscape reconstruction, and the consequent need for rigorous science to challenge and guide popular myths are demonstrated by Witt in his review of the use of stable isotopes. As Bowman states in his preface to the volume, there is a shift in focus toward a more socially complex and scientifically less certain approach to solving environmental problems. This change is occurring in concert with recognition of the importance of understanding the social and ecological history of ecological change at the scale of decades to centuries in formulating land-management strategies. This trend is well established in the United States but has scope for much greater growth in Australia and other parts of the world. Australia provides a particularly interesting case study (Dodson & Mooney's paper) because both agricultural and industrial changes occurred together and very recently. But although the focus of this volume is on vegetation dynamics (Start & Handasyde touch on faunal impacts) in Australian ecosystems, this collection of papers will have broad appeal to all conservation managers dealing with landscapes, soils, or plant or animal biodiversity. Landscape and vegetation change provides the template for fauna conservation and the understanding of ecosystem processes.