An ecological study of the grassland types of the central North Downs with refernce to their present structure and past origin

Abstract

The grasslands of the central region of the North Downs were surveyed and areas were found which do not appear to correspond in floristic composition to those described by other workers. Historical factors were believed to be important in determining the development of the anomalous sites, and investigations have been made both verbally among local farmers, and by reference to old maps and books to determine the time and nature of the land utilisation and the duration of natural reversion of these areas. It became possible to classify the anomalous areas according to the type of treatment to which they had been subjected.As many disturbed sites as possible were found, and areas of old grassland dominated by Bromus erectus and Festuca ovina were found in comparable situations of exposure and aspect for comparative purposes. All types of site have been subdivided according to aspect and species records made at the different seasons and frequency figures allocated by subjective methods.The thesis falls naturally into two parts. The first, dealing with a comparative study of the angiosperm components, end the second dealing with the bryophytes, attention being paid to the effect of aspect and exposure.Some very preliminary investigations have been made on the soils of the different sites.The appendix deals with some pilot experiments on the culture of some of the more critical bryophytes in the areas with a view to determining some of the factors controlling their restricted distribution.