Spatio-temporal modeling of the effect of selected environmental and land-use drivers on acid grassland vegetation

Spatial and temporal pin-point plant cover monitoring data are fitted in a structural equation model in order to understand and quantify the effect of selected environmental and land-use drivers on the observed variation and changes in the vegetation of acid grasslands. The important sources of measurement- and sampling uncertainties have been included using a hierarchical model structure. Furthermore, the measurement- and sampling uncertainties are separated from the process uncertainty, which is important when generating ecological predictions. Generally, increasing atmospheric nitrogen deposition leads to more grass-dominated acid grassland habitats at the expense of the cover of forbs. Sandy soils are relatively more acidic, and the effect of soil type on the vegetation includes both direct effects of soil type and indirect effects mediated by the effect of soil type on soil pH. Both soil type and soil pH affected the vegetation of acid grasslands. Even though only a small part of the temporal variation in cover was explained by the model, it will still be useful to quantify the uncertainties when using the model for generating local ecological predictions and adaptive management plans.

Evaluating Heathland Restoration Belowground Using Different Quality Indices of Soil Chemical and Biological Properties

Reversion of agricultural land to heathland and acid grassland is a priority for the conservation of these rare habitats. Restoration processes require interventions to reverse the effects of fertilization and acidity amelioration undertaken during decades of agricultural production. Belowground assessments of restoration success are few, and we have examined the utility of soil indices as a rationalized tool for land managers and restoration practitioners to assess the efficacy of restoration practice. To achieve this, we assessed a large number of variables, many of which might be near redundant, that could be optimized for such indices. We used a 14-year field experiment contrasting acidified pasture (treated with elemental sulphur), control (untreated) pasture, and adjacent native heathland and acid grassland sites. Based on biotic and abiotic parameters, several ‘heathland restoration indices’ (resembling soil quality indices) were generated using a minimum dataset identified through principal component analysis and a linear scoring system. For comparison we also conducted alternative analyses of all parameters, using nonmetric multidimensional scaling plots and analyses of similarity (ANOSIM). Use of heathland restoration indices showed that elemental sulphur application had changed the soil chemical conditions, along with the vegetation assemblage, to be comparable to that of native acid grassland, but not the belowground biology. ANOSIM on full datasets confirmed this finding. An index based on key variables, rather than an analysis of all biotic and abiotic parameters, can be valuable to land managers and stakeholders in acid grassland and heathland restoration.

Cotula alpina (Asteraceae) naturalised in the British Isles

Cotula alpina (Hook f.) Hook f. is an Australian herb that has been naturalised in Britain since the 1970s and is now locally abundant in parts of northern England and northwest Scotland. Its method of arrival is unknown but it is likely to have originated from gardens and perhaps also from wool shoddy. It appears to be spreading rapidly due to high seed production and effective dispersal by sheep, humans and vehicles and is now locally abundant on moorland tracks and in adjacent acid grassland and heather moorland managed for grouse. Due to its evergreen and mat-forming habit it can outcompete community dominants such as Agrostis capillaris and Festuca ovina in areas where levels of grazing are high. It appears to be well suited to the British climate and is therefore likely to spread into similar habitats in other regions where it could pose a threat to localized species associated with short grassland on acidic soils. Its overall abundance and ability to regenerate rapidly from seed means it is unlikely to be easily controlled or eradicated, although exclusion of grazing may help to reduce its abundance in some areas.

The Ecology of British Upland Landscapes. I. Composition of Landscapes, Habitats, Vegetation and Species

A primary requirement for policy objectives is reliable figures on the composition of any region. Currently there is no comprehensive, definitive set of statistics for the British Uplands, hence the present paper. An overview of the background to the region is first provided, together with some examples of the available figures and a discussion of their limitations. The paper uses a formal structure, with landscapes at the highest level followed by habitats, then vegetation, and finally species, with exact definitions of the categories applied at all levels. The figures are produced from a survey of stratified, random one kilometre squares. The tables give comprehensive figures for Great Britain (GB) as a whole, and also England, Wales and Scotland. The Uplands are shown to cover 38 % of the country. In terms of UK Broad Habitats, Bog is the most common overall (2062 k ha). It is estimated that 41 % of upland vegetation in Britain is grazed by sheep, and Cervus elephus (red deer) are particularly evident in Scotland. Walls (mainly drystone) are the most important linear feature (84 k km) but hedgerows (30 k km) are also widespread. The major vegetation classes are those linked to moorlands and bogs (about 25 %) but those associated with fertile soils are also common (10 %). In terms of species, Potentilla erecta (tormentil) is the most frequent species with four other acid grassland species in the top ten. Calluna vulgaris (ling heather) has the highest cover in Great Britain (14.8 %).