The Park Grass Experiment 2005

The Park Grass Experiment (PGE) at Rothamsted, UK is the longest running ecological experiment in the world.

Plan of the Park Grass Experiment in 1865

BBC Radio

Listen to a programme about the 150th anniversary of Park Grass

At Dandelions at Park Grass (c) Mike Dodd

Anthoxanthum odoratum

Read my Nov. 2005 article in New Scientist about Park Grass

New Scientist

It was set up by Lawes and Gilbert in 1856 and consists of a hay meadow to which a series of fertilizer treatments have been applied annually. The original aim was to look at the effect on yield of inorganic fertilizers especially phosphate and compare this with the effect of organic manures. However, it quickly became obvious that there were also large effects on species composition and it was decided to measure the percentage of each species in the hay. This has been repeated at irregular intervals to the present day. I have worked on the PGE since 1978 and we are conducting four projects on Park Grass at the moment:
  • Extinction risk in relation to extrinsic threats and intrinsic vulnerabilities in plants, with Helene Freville, Kevin McConway and Mike Dodd. (manuscript submitted)
  • A study of population genetic structure in sweet vernal grass (Anthoxanthum odoratum) in relation to climate and bottlenecks using choloroplast microsatellite and nuclear markers. This is Pamela Biss' PhD project, co-supervised by Joanna Freeland.
  • Sexual reproduction vs clonal growth in red fescue (Festuca rubra): is there a short-term advantage to sex? Ollie Barnett's PhD project, co-supervised by Joanna Freeland and now completed. Additional work is being carried out.
  • A review of the contribution of the Park Grass Experiment to ecology is in preparation for publication in 2006. Co-authors Paul Poulton and Johnny Johnson (Rothamsted Research) and others.

Silvertown, J., Poulton, P., Johnston, A.E., Edwards, G., Heard, M., & Biss, P.M. (2006) The Park Grass Experiment 1856 - 2006: Its Contribution to Ecology. Journal of Ecology, 94, 801-814.

Silvertown, J., Servaes, C., Biss, P., & Macleod, D. (2005) Reinforcement of reproductive isolation between adjacent populations in the Park Grass Experiment. Heredity, 95, 198-205.

Freville, H. & Silvertown, J. (2005) Analysis of interspecific competition in perennial plants using life table response experiments. Plant Ecology, 176, 69-78.

Crawley, M.J., Johnston, A.E., Silvertown, J., Dodd, M., de Mazancourt, C., Heard, M.S., Henman, D.F., & Edwards, G.R. (2005) Determinants of species richness in the park grass experiment. American Naturalist, 165, 179-192.

Biss, P., Freeland, J., Silvertown, J., McConway, K.J., & Lutman, P. (2003) Successful amplification of rice chloroplast microsatellites from century-old grass samples from the Park Grass Experiment. Plant Molecular Biology Reporter, 21, 249-257.

Silvertown, J., McConway, K.J., Hughes, Z., Biss, P., Macnair, M., & Lutman, P. (2002) Ecological and genetic correlates of long-term population trends in the park grass experiment. American Naturalist, 160, 409-420.

Wilson, J.B., Crawley, M.J., Dodd, M.E., & Silvertown, J. (1996) Evidence for constraint on species coexistence in vegetation of the Park Grass experiment. Vegetatio, 124, 183-190.

Dodd, M., Silvertown, J., Mcconway, K., Potts, J., & Crawley, M. (1995) Community stability: A 60-year record of trends and outbreaks in the occurrence of species in the Park Grass Experiment. Journal of Ecology, 83, 277-285.

Silvertown, J., Dodd, M., McConway, K., Crawley, M., & Potts, J. (1995) Species diversity and stability in grassland. Trends in Ecology and Evolution, 10, 287-288.

Dodd, M.E., Silvertown, J., Mcconway, K., Potts, J., & Crawley, M. (1994) Application of the British National Vegetation Classification to the Communities of the Park Grass Experiment Through Time. Folia Geobotanica & Phytotaxonomica, 29, 321-334.

Dodd, M.E., Silvertown, J., Mcconway, K., Potts, J., & Crawley, M. (1994) Stability in the plant communities of the Park Grass Experiment: The relationships between species richness, soil pH and biomass variability. Philosophical Transactions of the Royal Society of London Series B - Biological Sciences, 346, 185-193.

Silvertown, J., Dodd, M.E., Mcconway, K., Potts, J., & Crawley, M. (1994) Rainfall, biomass variation, and community composition in the Park Grass Experiment. Ecology, 75, 2430-2437.

Tilman, D., Dodd, M.E., Silvertown, J., Poulton, P.R., Johnston, A.E., & Crawley, M.J. (1994). The Park Grass Experiment: Insights from the Most Long-Term Ecological Study. In Long - Term Experiments in Agricultural and Ecological Sciences (eds R.A. Leigh & A.E. Johnston), pp. 287-303. C a B International, Wallingford, United Kingdom 0X10 8DE.

Silvertown, J. (1987) Ecological stability: a test case. American Naturalist, 130, 807-810.

Silvertown, J.W. (1980) The dynamics of a grassland ecosystem: botanical equilibrium in the Park Grass Experiment. Journal of Applied Ecology, 17, 491-504.






These three figures illustrate some of the most important results from Park Grass. They show how:

1. The application of different nutrients influences the relative ratios of three plant guilds: grasses (poaceae), legumes (fabaceae) and other broad-leaves.

2. Precise G:L:O ratios vary from year to year under the influence of climate.

3. Despite the perturbations caused by climate, the ratio remains around an equilibrium value that is characteristic for each treatment. This means that, at the guild level, the PGE communities maintain a dynamic equilibrium. How the community does this is an interesting question because the species within each guild change over time. Hence, the communities are hierarchically organized.

See the right hand panel for references.

We are now studying the population genetics of species on the plots, which is revealing another layer of detail in the system.