Biomass production of upland vegetation types in England and Wales

Abstract

Abstract The objective of the study was to describe the annual and seasonal production of live biomass of six plant species or communities of the uplands of the UK –Calluna vulgaris, Vaccinium myrtillus, Nardus stricta, Molinia caerulea, Eriophorum vaginatum and Agrostis–Festuca grassland. The species or communities are important for the management of the uplands to meet both biodiversity and agriculture objectives. The annual and seasonal production of live biomass was determined for sites within six regions of England and Wales in 1995, 1996 and 1997. The six regions were North‐east England, North‐west England, North Pennines, South Pennines, South‐west England and Wales. In each region, the Institute of Terrestrial Ecology's Land Classification Scheme was used to select three or four 2 km × 2 km squares that contained a mosaic of C. vulgaris and upland grassland plant species. Uniform plots of 1 ha were selected from each 2 km × 2 km square, within which three measurements were made on each sampling occasion. Biomass of each species or community was measured within 1·0 × 0·5‐m quadrats using the same standard procedures. Measurements of annual production of current season's shoots of the pioneer, building, mature and degenerate phases of C. vulgaris and of V. myrtillus were made in October, and of the annual production of live biomass of N. stricta, M. caerulea and E. vaginatum in August. A simulated grazing regime was imposed for the Agrostis–Festuca grassland with cuts being made to a height of 4 cm at 8‐week intervals. The annual production of live biomass produced was estimated as the sum of four harvests taken during the growing season. Seasonal measurements of the amount of live biomass of all the species were also made in April, June, August and October. For C. vulgaris, there were significant (P = 0·05) differences between the pioneer, building, mature and degenerate phases in the annual production of current season's shoots, with greater amounts being produced by the phases of greater age and with higher biomass. There were significant year (P < 0·05) and region (P < 0·05) effects, with the lowest production in 1995 and in the South‐west of England. The values were higher than those observed in previous studies in Scotland, and these were interpreted as being associated with a longer growing season rather than higher summer temperatures. There was no difference between years and regions in the annual production of V. myrtillus. For the grass species, there were small differences in annual production of live biomass between years and regions. However, the annual production of live biomass of N. stricta was significantly (P < 0·01) lower in 1995 than in 1996 and 1997 and significantly (P < 0·001) lower in the South Pennines region than elsewhere. The effect of a range of weather and other environmental variables on the annual production of live biomass of each species of grass was explored, but they provided only a limited insight into the reasons for the observed differences and were found to be of limited value as predictors.