Succession of disturbed and undisturbed chalk grassland at Aston Rowant National Nature Reserve: details of changes in species.
Abstract
A randomized block design experiment on succession at Aston Rowant, UK was recorded from 1969 to 1982. The treatments were annual grazing, and no grazing, alone, or after disturbance by burning or rotary tillage in 1969. Changes in cover of 32 common flowering plants in the field layer over 14 years are tabulated. In relation to succession in the ungrazed plots, species were grouped into 4 categories, those which (a) gained in cover (especially tall coarse grasses), (b) increased initially, then declined (more characteristic of disturbed treatments), (c) decreased (mainly smaller and shorter-lived species) and (d) showed no consistent gains or losses. In the disturbed plots, especially with rotary tillage, many seed-bank species appeared, several subsequently persisting for many years. Corylus avellana and Tamus communis colonized a few plots after several years, indicating the importance of dispersal rather than the stage of succession reached. Seed dispersal from plants in the different treatments suggested that long-term succession experiments should include barrier areas. The original flora was not entirely eliminated during 14 years of secondary succession and could probably be reclaimed. This highlights the value of information about expected seral changes as well as descriptive accounts of the present vegetation for managers of nature reserves.