Despite the large quantity of research, there is still little understanding of
the long term impact of environmental drivers of change, especially when they act in combination. Understanding the long term impact is vital to enable future mitigation through conservation practices to be successful. This thesis evaluated the long term impact of environmental change drivers on soils and vegetation in Snowdonia National Park, by revisiting historic survey sites. Chapter 3 revisited soil and vegetation plots recorded as part of the International Biological Programme, Chapter 4 revisited soil sampling sites recorded as part of the Field Studies Council Soils of Snowdon study, whilst Chapters 5 and 6 utilised a long term grazing exclusion experiment set up across Snowdonia.
Overall, both the soils and vegetation in Snowdonia showed significant changes when compared to their historic condition. Although in some cases, an increase in soil pH appeared to indicate a recovery from historic acidification, it was apparent that this increase was not large enough to return the soils to their pre 1960s levels. Contrasting results were found for bryophytes and higher plants however, as higher plants indicated more acidic conditions in the present day than previously. Whilst a number of drivers of environmental change were considered, the evidence indicated that acidification, most likely from historic sulphur deposition, was the main driver of the changes identified.
Despite large reductions in sulphur deposition it is evident that the environment has yet to recover from the wide scale acidification that took place. Vegetation is already displaying a negative response to current levels of disturbance, and with climate change predicted to intensify, the resilience of already degraded ecosystems to further disturbance is uncertain, and continued field-based studies that examine the interactive effects of multiple environmental change drivers are required.