Further studies in the population dynamics of some Teesdale plants

The population dynamics, life-histories, and reproductive strategies of a number of rare plants in the Upper Teesdale National Nature Reserve have been studied in detail over a three year period. Results from a seven year period have been analysed, and information presented on the changes in numbers, mortality rates, recruitment rates, and reproductive behaviour of Viola rupestris. Polygala amarella. Gentiana verna and Viola rupestris x riviniana with particular reference to different site conditions. The mortality patterns of even-aged cohorts of plants have been followed, and mathematical models fitted to their rates of decline. The relative contributions of sexual and vegetative reproduction to the population numbers have been analysed, and the different reproductive strategies related to different environmental conditions. Life-cycles have been constructed for some species, and those points of the life-cycle where the greatest losses of plants occur have been revealed. The study has also sought to analyse any effects on the rare plant populations caused by the presence of the recently- constructed Cow Green reservoir, and future management of these rare plants is considered in the light of the information collected.