Napoleon Bonaparte once said ‘History is the version of past events that people have decided to agree upon’. Perhaps nowhere is this truer than in seeking an understanding of species distributions and vegetation patterns from the past. Historical biogeography is often controversial, with competing ideas and viewpoints waxing and waning with the publication of new findings. Journal of Ecology is often at the forefront in publishing high profile papers that contribute important new information relevant to these controversial topics. For example, a few years ago Mitchell’s (2004) paper in the journal stepped into the centre of an on-going controversy contrasting the ‘high-forest’ and ‘wood-pasture’ hypotheses about the extent and causes of forest cover around the onset of human activities in northwestern Europe c. 6 000 years ago (Birks 2005). Using paleoecological data, Mitchell cast serious doubt on the validity of the wood-pasture hypothesis that had been recently adopted by a number of government agencies for framing forest management policies.
In a similar vein, Svenning et al.’s (2008) paper in the latest issue of Journal of Ecology investigates a key issue for understanding biodiversity during the Pleistocene Last Glacial Maximum (LGM) 21 000 years ago. The traditional ‘southern refugia hypothesis’ suggests that a largely treeless plain existed at this time, with large glaciers and permafrost covering much of Europe, and trees restricted to scattered Mediterranean refugia. By contrast, Svenning and colleagues use species distribution modeling to support the controversial ‘northern refugia hypothesis’ which suggests that climatic conditions were in fact suitable to allow at least some boreal forest tree species to exist across large areas of Europe.
Svenning’s group estimated the potential distribution of 7 boreal and 15 nemoral trees using 5 different species distribution models. Modern species distributions were used to calibrate these models and projected onto two LGM climate simulations for Europe. Although not all models and climate simulations projected the same distributions, it was clear that boreal species probably existed across Central and Eastern Europe and into the Russian Plain, supporting the northern refugia hypothesis. By contrast, potential distributions of nemoral species were restricted to the Mediterranean and Black Sea regions, supporting the southern refugia hypothesis. Paleoecological and phylogeographic data from separate recent studies support these findings.
The implications are that a revision of our view of LGM vegetation in Europe is required. Europe during the LGM was not the treeless plain envisaged previously. Such a different view of past vegetation patterns helps explain seemingly anomalous fossil mammal assemblages, and has implications for projected vegetation patterns under future climate change scenarios.
Lead author of this month’s Editor’s Choice paper, Jens-Christian Svenning, is no stranger to controversy. He earlier suggested the re-wilding of Europe by reintroducing some of the megafauna (such as lions, spotted hyenas and leopards) that were extirpated in the late Pleistocene (Svenning 2007). We expect his paper published in Journal of Ecology to attract similar attention.
Other papers in the current issue of Journal of Ecology with implications for climate change include Turetsky et al. (2008) and Miller-Rushing et al. (2008). Merritt Turetsky and her colleagues show that a number of peatland mosses may not decompose as rapidly as expected with rapid climate warming, potentially stabilizing peatland carbon loss. By contrast, Abraham Miller-Rushing and his colleagues show that one of the commonly used indicators of climate change effects, namely first flowering dates, may not always be the sensitive indicator researchers thought. Both papers, along with Svenning et al., are important contributions to the climate change literature and essential reading for researchers and policy makes in this area.
Editor, Journal of Ecology
- Birks, H.J.B. (2005) Mind the gap: how open were European primeval forests. Trends in Ecology and Evolution, 20, 154-156. Miller-Rushing, A.J., Inouye, D.W. & Primack, R.B. (2008) How well do first flowering dates measure plant responses to climate change? The effects of population size and sampling frequency. Journal of Ecology, 96, 1289-1296.
- Mitchell, F.J.G. (2004) How open were European primeval forests? Hypothesis testing using paleoecological data. Journal of Ecology, 93, 168-177.
- Svenning, J.-C. (2007) Slide show: Bringing back Europe’s prehistoric beasts. Scientific American.
- Svenning, J-C., Normand, S. & Kageyama, M. (2008) Glacial refugia of temperate trees in Europe: insights from species distribution modeling. Journal of Ecology, 96, 1117-1127.
- Turetsky, M.R., S.E. Crow, R.J. Evans, D.H. Vitt. & Wieder, R.K. (2008) Tradeoffs in resource allocation among moss species control decomposition in boreal peatlands. Journal of Ecology, 96, 1297-1305.
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