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Choose a Project: Projects Home Page 1. Atmospheric CO2 & Leaf Evolution 2. Polar Forests - Carbon Balance 3. Polar Forests - Distribution and Ecology 4. Biogenic Trace Gas Fluxes 5. The Evolution of C4 Plants 6. Palaeoceanographic changes 7. Biodiversity Response to Climate Change 8. Evolution of C4 Photosynthesis 9. Terminal Cretaceous Climate Change 10. C4 phylogenetic history

Personnel
Principal investigators:

Post-doctoral research associate:
Graduate student:

Professor D.J. Beerling
Professor J.E. Francis
Dr S. Brentnall
Melise Harland

Summary
Widespread forests in the polar regions between 250 and 50 million years ago have some important consequences for regional and global climates of the time. But numerically quantifying these consequences with any degree of realism poses some substantial difficulties, not least because we have to link past forest growth with that of modern forests. This need has required us to develop a new interdisciplinary approach which is underpinned by a computer model of forest growth which scales up from leaf lifespan (Osborne & Beerling, 2002). In our model, increasing leaf life-span will have cascade effects from the leaf to the whole ecosystem level influencing the productivity and carbon sequestration of forests, soil nutrient cycling and their exchange of energy and materials with the atmosphere (see figure).

Schematic illustration showing the
different means by which forests influence climate.

A key element of this project will be to determine the leaf lifespan of fossil woods of conifers that made up the ancient polar forests. This task is being undertaken by Melise Harland - see Project 7 for more details. Basically, we adopt techniques which quantify how marked the growth rings are in fossil woods. Most importantly, this approach allows for the first time a determination of leaf life-span from analysis of fossil woods. Estimates of leaf lifespan from the fossil seed our computer model, and thus establishes a vital means of linking past and present tree physiology.

Cascading effects of increasing conifer leaf life-span on ecosystem processes, and their down-stream potential to influence nutrient cycling and vegetation-climate interactions. Broken line shows the coupling required to achieve feedbacks on forest function.

Our aim is to develop an integrated approach for understanding polar forest biogeography and climate interactions by developing new techniques of modelling based on leaf life-span. We will be quantitatively assessing their feedback on regional polar climates of both hemispheres by embedding our conifer forest model in the U.K. Meteorological Office general circulation climate model www.met-office.gov.uk.

Check out our latest research findings by clicking on the logo to download the paper below:

Osborne, C.P. & Beerling, D.J. (2002) A process-based model of conifer structure and function with special emphasis on leaf lifespan. Global Biogeochemical Cycles. 1721KB

Dawn redwood (Metasequoia) trees growing in the Northern hemisphere.

Jane Francis on a fossilized Nothofagus tree trunk in the Antarctic. The fossil (not Jane) dates to the Cretaceous and provides tangible evidence for the presence of fossil forests there 100 million years ago.

Fossil evidence from Axel Heiberg Island, in the Canadian Arctic, tell us that forests like these once covered polar regions in the Northern hemisphere with important consequences for the climate.

A Nothofagus forest in New Zealand (photo. Ian Woodward). These forests may represent a possible analogue for those on Antarctica in the Cretaceous.