RESUMO
BACKGROUND: It is obvious to anyone studying plants in the landscape that man-made environmental change is having profound effects on the abundance, distribution and composition of plant communities. Nevertheless, quantifying these changes and estimating the impact of the different drivers of change is extremely difficult. Botanical surveying can potentially provide insights to the changes that are occurring and inform decisions related to conservation, agriculture and forestry policy. However, much of botanical surveying is conducted in such a way that it is not comparable between dates and places. Any comparison of historical and modern data has to account for biases in the recording of different taxonomic groups, geographic biases and varying surveying effort in time. In 2010 botanical recorders in the Vice Counties of Durham and South Northumberland in the United Kingdom decided to conduct a four year survey specifically to benchmark the abundance and distribution of common plants in their counties. It is intended that this survey will provide a relatively unbiased assessment with which to compare future and past surveys of the area and a means to study the drivers of biodiversity change in the North-east of England. NEW INFORMATION: This survey of Durham and South Northumberland has been designed with two goals, firstly to provide information on common vascular plant species and secondly to provide a dataset that will be versatile with respect to the sorts of questions that can be answered with the data. The survey is primarily an occupancy study of 1km(2) grid squares, however, observers were also asked to provide a relative abundance estimate of the species in each grid square. The collection of relative abundance estimate data was an experiment to assess the repeatablity and useablity of such estimates.
