Succession of disturbed and undisturbed chalk grassland at Aston Rowant National Nature Reserve: dynamics of species changes

Published source details Ward L.K. & Jennings R.D. (1990) Succession of disturbed and undisturbed chalk grassland at Aston Rowant National Nature Reserve: dynamics of species changes. Journal of Applied Ecology, 27, 897-912.
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Summary

In the UK, ancient chalk grasslands support a high diversity of characteristic plants and invertebrates. However, these are vulnerable to successional changes when grazing is reduced or ceases altogether. Most management on reserves is related to past agricultural or silvicultural practices, but these may not necessarily be the best methods of conservation management. This paper investigated changes in plant species composition in experimental plots in grazed and ungrazed grassland (with or without burning or rotovation as novel management techniques) over 14 years of succession.

Study site: The study was undertaken at Aston Rowant National Nature Reserve (National Grid ref. SU 730966), Oxfordshire, southern England.

Experimental design: The experiment was a randomized block design (4 replicates of 4 treatments): annual grazing, no treatment, and ungrazed after disturbance by burning or rotavating in 1969. Plots were10 x 12 m, on shallow chalky soils.

Monitoring: Vegetation change over 14 years of succession (1969 to 1982) were monitred. Flowering plants were recorded (using the Domin scale) in the last week of June every year from 1970 (only presence/absence was recorded in 1969), in two radomly positioned permanent 1m² quadrats/plot.

In the plots, 148 vascular plant species were recorded over 14 years. Numbers of species per plot varied from 32 to 78, but there were no marked trends in species change over the 1969-82 recording period.

Species declines (albeit small) were least in the grazed grassland, intermediate in burnt quadrats and greatest in the untreated and rotavated quadrats. Numbers of species annually colonizing and lost tended to fluctuate in a similar way regardless of treatment. Declines and fuctuations were probably attributable to climatic influences e.g. a drought in 1976 reduced species number by over 10% in most plots.

Conclusions: There was considerable variability in plant response between blocks and treatments. Burning perhaps produced the most stable conditions, as the loss of the original species present was slower than in either the ungrazed or rotavated treatments.

Note: If using or referring to this published study, please read and quote the original paper, this can be viewed at: http://links.jstor.org/sici?sici=0021-8901%28199012%2927%3A3%3C897%3ASODAUC%3E2.0.CO%3B2-C