Authors:R. J. Pakeman, R. J. Pakeman, S. A. Hinsley, S. A. Hinsley, P. E. Bellamy, and P. E. Bellamy
The favoured state approach sensu Fox (1987) was used to investigate the existence of assembly rules for woodland bird communities in an agricultural landscape. When birds were classified according to gross breeding habitat requirements, year-round resident, .true. woodland species showed an excess of favoured states suggesting a possible assembly rule. There was weaker evidence for a similar assembly rule governed by foraging requirements. This pattern was shown for all woods together, and for most categories of woods, grouped according to size, shape or size and shape together. Summer migrants did not show such patterns, and their arrival appeared to mask any patterns established by year-round resident species. The statistical significance of the excess of favoured states was highest in 1990, when bird population densities were considerably higher than in 1991 and 1992. Interspecific competition appears to be a factor in structuring woodland bird communities within the area sampled. Some implications for the action of these assembly rules on the results of further habitat fragmentation are discussed.
Authors:N.A. Littlewood, S. Greenwood, S.L.O. Quin, R.J. Pakeman, and S.J. Woodin
Restoration of moors dominated by Calluna vulgaris is carried out for conservation and sporting reasons. Previous research has shown variable restoration success in the early years of restoration management. In this study we investigated whether restored heather moorland vegetation increasingly resembles long-established moorland vegetation over a longer time period. Vegetation at seven moorland restoration sites (six in northern England and one in Scotland) was sampled in 2003 (to assess short-term restoration success) and 2010 (to assess long-term restoration success). Three of these sites were restored solely by grazing control and four by a suite of more intensive techniques. On each visit, vegetation sampling was carried out in degraded, restored and long-established control areas at each site. Restored vegetation assemblages closely resembled control assemblages. The samples were, though, dominated by the species targeted for management, Molinia caerulea and Nardus stricta in degraded samples and Calluna vulgaris in control samples. Discounting these species and concentrating on the remainder of the vegetation assemblage, areas restored solely by the reduction or removal or sheep grazing more closely resembled control assemblages whilst those managed more intensively were more intermediate between degraded and control assemblages. There was no systematic pattern of change in restored areas between the sampling dates. At two sites restored samples become more similar to control samples whilst restored samples at other sites either showed little change or moved back towards a degraded assemblage. Thus whilst moorland restoration can succeed in re-establishing C. vulgaris, we found no evidence of a systematic shift in the remainder of the vegetation assemblage towards that of a long-established moor over the time period studied.