There is a need for active monitoring of organisms and habitats in the wild, not just for curiosity, but to inform us of the changes that are occurring. Environmental change is often reported anecdotally and causation is assumed, but without at least semi-quantitative measurements we cannot hope to unravel the complex interacting factors that are really driving changes. Data are needed to inform decision makers on all aspects of management that affect the countryside, including conservation, land management and farming.

The North-east of England is fairly typical of the landscapes found in the rest of the United Kingdom. It has large urban areas, a long coastline, large expanses of arable land, extensive grazing land, forestry and upland moorland. For biological recording purposes Great Britain and Ireland are divided into Vice Counties, which have permanent borders. The Botanical Society of Britain and Ireland appoints voluntary Vice County Recorders (VCR) to each Vice County and this survey is the result of a collaboration between the VCRs of Durham (JD) and South Northumberland (AJR, QG). The region has a number of active amateur biological recorders and this survey was also seen as a means to give direction to their recording effort.

There are many factors driving biodiversity change in the North-east England, most are common to other areas of Northern Europe, whereas others are more local. Below are listed some of these drivers that could be explored further using these data.

Eutrophication from agricultural fertilizers, waste and atmospheric deposition has become an insidious and pervasive driver of habitat change (Duprèˆ et al. 2010, Phoenix et al. 2006, Stevens et al. 2004). Not only does eutrophication impact places where there is direct application of fertilizer, such as on farmland, but also isolated wild areas are affected through atmospheric deposition. Atmospheric nitrogen deposition is also a cause of soil acidification, to which sulphur emissions also contribute, though the latter have declined in recent years.

A particular land use change to the North-eastern England has been the conversion of peat moorland into conifer plantations. A notable example in South Northumberland is Kielder Forest, the largest man-made forest in England, it covers 60,000 hectares in the west of the county along the Scottish and Cumbrian border (Forestry Commission, England 2006). About three-quarters of the plantation is Sitka spruce (Picea sitchensis (Bong.) Carr) and there are also large plantations of Norway spruce (Picea abies (L.) Karsten) and Scots Pine (Pinus sylvestris L.).

Artificial drainage has also been the cause of significant habitat change. A notable historic example was the drainage of Prestwick Carr in the 19^th century that led to the local extinction of many species (Groom et al. 2014). The few remaining lowland wetlands are now largely protected from drainage. However, drainage of the uplands is still continuing in order to extend conifer plantations.

Farming practises directly and indirectly change habitats and the landscape. The mechanization of farming occurred some time ago, as did the introduction of modern herbicides and pesticides; however, agriculture continues to change with the introduction of new crops, the changing profitability of livestock versus arable farming and new policies intended to promote good stewardship of the countryside (Robinson and Sutherland 2002, Storkey et al. 2011). Even on non-agricultral land the use of amenity seed mixes to vegetate large areas has changed natural vegetation and introduced non-native taxa and novel genotypes of native species.

Urbanisation, industrialisation and associated development have profoundly changed the environment locally within the region, especially in the eastern lowlands. Smaller-scale developments are ongoing, but mostly confined to areas that have already been developed. Mining of various minerals was a particularly important economic activity in this region and few parts of the region were unaffected by it. Following the relatively recent decline of the coal industry, many former coal mine sites were landscaped and ‘tidied up’. In more recent times mining and quarrying activities have been more localised. Opportunities for wild plants to colonise and survive have been dramatically altered by all of these activities.

Alien species may also have an impact on native communities, though it is difficult to separate their influence from other habitat change. Alien plants exert competitive pressure, but there are also emerging diseases and introduced animals that may exert a pathogenic or herbivorous pressure. The distribution ranges of insects have been moving north in recent years, presumably as a consequence of climate change (Hill et al. 2011). Climate change may ultimately have the greatest impact on the diversity and distribution of plants, but so far its impact on plant distributions is not yet clear above the signal of other environmental change (Groom 2013).

Observations of wild plants in the counties have been made at a number of different spatial resolutions, 1km2, 4km2, 25km2 and 100km2. However, the trend in recent years has been towards finer resolutions. This has been driven by the availability of digital systems for storing observations and by access to systems for mapping and analysing the data. The current survey used a grid of 1km2 and although even finer resolutions would give greater sensitivity to change, 1km2 grid squares are advantageous from many perspectives. This resolution is close to the scale of many landscape features in the English countryside, fields, towns, lakes and hills. They allow surveyors to cover a large area in a reasonable amount of time. This grid square is also clearly indicated on Ordnance Survey maps and on Global Positioning Systems.

From a policy perspective much emphasis is placed on the conservation of rare species even though common plants are those that are most important for ecosystem health and function. The focus of this survey is on those common species and their habitats.

From a statistical perspective there are a large number of options for distributing survey sites. For example, stratification can be used to ensure even representation of different habitat types. Sites can also be distributed non-randomly to evenly cover the environmental space of an area and reduce the impact of spatial autocorrelation. Nevertheless, a completely random approach was chosen to make the results as versatile as possible for whichever questions may in the future be resolved using these data. Some types of analyses may have reduced statistical power when used with a completely random design, but a random survey avoids having to make assumptions about the drivers of changes that may occur in the future and their location.

This approach is not strongly hypothesis driven. However, this is not necessarily a disadvantage. To some extent hypothesis driven monitoring is likely to produce more robust results than undirected monitoring. However, it can also be argued that general monitoring has the advantage of detecting unexpected changes that targeted monitoring would miss (Wintle et al. 2010). We have seen, and expect to see further environmental change in this region. Some of those future changes are already known, such as climate change. However, the stochastic nature of the environment and the unpredictability of human activities mean that accurate forecasting is impossible. The challenge in the future will be to use these data to identify real change before it becomes readily apparent and use the results to adapt policy in a positive way.

Former botanical surveys of the North-East of England

Suggested use of the data

The unsurveyed grid squares are at odds with the goal of having an unbiased dataset that covers the two counties. South Northumberland was almost completely surveyed, but County Durham was incompletely surveyed with unsurveyed squares concentrated particularly in the south. There was no obvious prejudice of recorders against particular habitats; however, it appears that these unsurveyed squares are unsurveyed because they are distant from the homes of active surveyors.

Apart from ignoring these missing data, users of these data could resolve this problem in at least two ways. Analysis could be conducted only on the well-surveyed portion of the area, or surveys conducted before 2010 or after 2013 could be used to fill gaps where these observations exist. Eleven of the unsurveyed squares had surveys from between 1998 and 2009 and these surveys have been included in the dataset.

To demonstrate a potential use of these data, universal kriging has been used to interpolate DAFOR scores for Calluna vulgaris (Fig. 3a). The associated kriging variances conveniently demonstrate where there are spatial information gaps (Fig. 3b). This map clearly shows the large degree of uncertainty in southern Durham. Another gap is in the north-west of the area where the Otterburn Firing Ranges prevented access. There is also an obvious edge effect to the interpolation where, owing to the random distribution of the sites, locations at the edge of the region are supported by fewer neighbouring sampled sites.

a

b

Figure 3.

Interpolated abundance estimates of Calluna vulgaris in South Northumberland and Durham using kriging. The method is described in Bivand et al. 2008, Groom 2013, however the DAFOR score is converted to a numeric value for kriging, zero is used for non-detections and one to five for rare, occasional, frequent, abundant and dominant, rather than using only presence or absence. The vice county boundary data is public sector information licensed under the Open Government Licence v3.0.

a: The interpolated abundance estimated from DAFOR scores of Calluna vulgaris from all surveys. Interpolation was conducted using universal kriging with altitude used as the covariable. The variogram was constructed using a width of 2,000m and a cutoff of 40,000m.  
b: The kriging variances of the interpolated DAFOR scores.  

This paper is dedicated to the memory of the Reverend George Gordon Graham who contributed so much to our knowledge of the region's flora and passed away in 2015.

We would also like to thank all the observers and supporters of wildlife conservation in the North-east of England. Their interest in wildlife and their belief in the importance of biodiversity sustains projects such as this.