Plant communities represent a dynamic balance between competing species. Environmental factors such as nutrient availability and herbivory may alter this balance and cause changes in community composition. This research aims to quantify the interacting effects of changes in grazing levels and increasing nutrient inputs on a model nutrient-poor ecosystem, heather moorlands. A combination of field and laboratory experiments will be used to gain a better understanding of the mechanisms by which grasses are replacing heather in this ecosystem. Both nutrients and herbivory will be manipulated to assess the role of herbivory in driving moorland sucessions and to measure how the competitive abilities of moorland plants are related to their growth form and life-history strategies.This research will aid the development of management plans to protect a habitat of international conservation importance.