Imperial College of Science, Technology and Medicine
Department of Biological Sciences
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MJ Crawley FRS Plant Ecology |
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Research Interests:
Research is focussed on two interrelated questions: How does feeding
by herbivorous animals affect the distribution and abundance of plants?
And how do changes in the abundance and quality of plants influence
the distribution and abundance of herbivores? The aim is the development
of theory to take explicit account of the features that make plant-animal
interactions so distinctive. A major difference from predator-prey models
is that the herbivore feeding typically does not kill the plant (seed-
and seedling-feeders excepted). In this regard, a plant-herbivore interaction
is more akin to a host-parasite system, but it differs in the fact that
most plants show relatively well developed mechanisms for compensating
for herbivore attack. This means that the rate of damage to the plants,
and hence fitness loss, is typically a non-linear function of the rate
of herbivore feeding. Another major difference is that variation in
food quality experienced by herbivores is much greater than for carnivores.
This means that changes in plant quality that are caused by herbivore
feeding (e.g. induced defences, or changes in nitrogen content of regrowth
foliage) have the potential to feed back and influence the subsequent
growth, reproduction and mortality of herbivores. Theoretical work is
supported by field studies on a range of model systems.
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Long term research on acorn production and recruitment biology of English oak (Quercus robur) has shown the importance of predator satiation for the production of strong cohorts of tree recruits. This is the specialist acorn-feeding weevil Curculio glandium. |
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The larvae of insect herbivores (like this swallowtail butterfly on its host plant Ferula communis (Apiaceae)) can have major impacts on plant growth and seed production. Whether or not this affects plant population dynamics depends upon whether or not recruitment is seed-limited or microsite-limited. |
| Adult insect herbivores are amongst the most attractive of all insects. This South American species is part of a large mimicry ring. |
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| The rabbit (Orictolagus cuniculus) is a keystone species in Silwood Park where most of our field studies are carried out. Grazing by rabbits prevents recruitment of woody plants and stops succession from grassland to woodland. Within grasslands, rabbit grazing reduces the abundance of palatable species and, indirectly, causes an increase in the abundance of unpalatable species as a result of competitor release. |
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Selected Publications:
1. Crawley, M.J. 1983. Herbivory. The Dynamics of Animal-Plant Interactions.
Blackwell Scientific Publications. Oxford.
2. Crawley, M.J. . 1997 [Ed] Plant Ecology. 2nd Ed.. Blackwell
Science. Oxford.
3. Crawley, M.J. 1992 [Ed] Natural Enemies. Blackwell Scientific
Publications. Oxford.
4. Crawley, M.J. 1993 Glim for Ecologists. Blackwell Scientific
Publications. Oxford.
5. Crawley, M.J. 2002. Statistical Computing: An Introduction to
Data Analysis Using S-Plus. John Wiley
The web site associated with the book is at http://www.bio.ic.ac.uk/research/mjcraw/statcomp/
6. Crawley, M.J. 2005. The Flora of Berkshire. Brambleby Books, Harpenden.
The web site associated with the book is at http://www.imperial.ac.uk/bio/research/crawley/floraberks
7. Crawley, M.J. 2005. Statistics: An Introduction Using R. John Wiley,
New York
The web site associated with the book is at http://www.imperial.ac.uk/bio/research/crawley/statistics
8.
Crawley , M.J. 2007 The R Book. John Wiley, New York
The web site associated with the book is at http://www.imperial.ac.uk/bio/research/crawley/therbook
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This is the famous Park Grass Experiment at Rothamsted. It was begun in 1856 and has a continuous record of hay yields since then. Many of the 100 or so plots on Park grass are as close to equilibrium plant communities as we know of from anywhere in the world. This unique resource allows us to study important questions about coexistence, the maintenance of species richness and the determination of relative abundance. |
| The impacts of herbivores are often subtle but here, in the Cheviot Hills on the border between England and Scotland, herbivore feeding colours the whole landscape. The purple area on one side of the boundary wall is lightly grazed heather (Calluna vulgaris, Ericaceae), while the pale area on the opposite side is the unpalatable grass Nardus stricta on heavily grazed land carrying a relatively high density of sheep. |
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Two individual oak trees (Quercus robur) showing pronounced differences in the timing of leaf fall in autumn (the early colouring individual on the right also busts its buds earlier in spring). Phenology - the scientific study of the timing of things - is a vital part of plant-herbivore investigations, because subtle differences in timing can have enormous impact on food quality for the herbivores and the likely rates of damage suffered by the plants. |
Contact Details:
Professor MJ Crawley FRS
Department of Biological Sciences
Imperial College at Silwood Park
Ascot
Berkshire
SL5 7PY. UK.
Tel: 44 (0) 207 5942 216
Fax: 44 (0) 0207 594 2339
E-mail: m.crawley@ic.ac.uk
Links to Further Information:
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