1. The blanket bogs of the southern Pennines and Peak District are severely degraded, attributed to centuries of poor land management, wildfire and atmospheric pollution. Restoration efforts have focussed on the revegetation of bare and eroding peat surfaces, with considerable success. 2. Sphagnum mosses provide the form and function of blanket bog, with their remains making up the majority of the peat body. These species were lost from the region and remain largely absent, despite restoration efforts. 3. As a keystone species of peatlands, their return is essential to the continued provision of ecosystem services derived from these uplands. Hence, their reintroduction is of great importance. 4. Preliminary trials determined Sphagnum can be reintroduced to numerous degraded conditions found on blanket peat, with S. fallax the best performing species. Water availability was strongly implicated as a significant factor, with drought proving fatal to propagules. In areas of dense vegetation, flailing has the potential to increase establishment, but requires further verification. 5. Growth trials indicated the legacy of atmospheric pollution was still exerting influence upon the growth of Sphagnum. Peat from the southern Pennines region was shown to contain elevated concentration of numerous pollutant heavy metals and nutrients. A comparative study of some UK bogs demonstrated the consequences of biogeochemical characteristics, whilst further implicating the importance of water availability in degraded sites. 6. The potential of Sphagnum reintroduction to degraded sites was demonstrated, within the constraints of shorter time scales. Over longer periods, with increased experimentation and subsequent monitoring, further understanding will undoubtedly be gathered. It is essential this knowledge is shared, updated and applied by conservation agencies and parties conducting such work.

No description available.

In order to define the present status of the genus Atrichum in Britain, data available from various floras and other publications are examined. Also literature relating to the cytology of the bryophytes is reviewed. Herbarium and living specimens are examined, the latter both in the field and under controlled conditions, to establish the range of variation in each species and to determine whether this is of genetic or environmental origin. Finnish and British material of A. tenellum are compared and two new races of A. undulatum, with distinct morphology, are described. Cytological investigation shows that A. crispum, A. angustatum and A. tenellum are all present as N=7 races in Britain. A. undulatum occurs mainly as the N=21 race with sporadic aneuploid specimens, but diploid (N=14) races, of very local distribution, also occur. The use of certain characters for species identification is discussed in the light of the results obtained in the investigation and the cytological basis of sex expression in the genus is discussed with particular reference to A. undulatum. Finally the species and races of Atrichum in Britain are described.

Nitrogen enrichment in sensitive habitats has become a matter of concern in recent years, and has led to the need to develop a bio-monitoring scheme that could be used by non-specialists to undertake site evaluation across the UK. Epiphytes are ideal candidates for such a project due to their high sensitivity to atmospheric pollutants. Indicator species analysis identified a comprehensive UK-specific list of epiphytic indicators for NH3 pollution in the UK that for the first time also included microlichens. A shortlist of easily identifiable, widely distributed indicator species was produced from these and used to trial the effectiveness of a frequency based scoring system. A simple, un-weighted frequency based scoring system founded on the Lichen Acidophyte Nitrophyte index was found to correlate strongly with NH3 concentrations in air. Assessment of other atmospheric chemistry and climate variables with the scoring system showed that NO2 concentrations in air and bark pH were confounding factors. The influence of pH was further validated by observations in a field experimentation plot where different N forms were applied. In order to address this, a regression equation was formulated that incorporated NH3, NO2 and bark pH to produce a predictive model that could potentially be used to evaluate site condition with respect to atmospheric N pollution, as defined by the combined effect of NH3 and NO2. Investigations into the biochemistry of an indicator species identified that rates of phosphomonoesterase (PME) activity were higher in N-sensitive species than N-tolerant ones. N-sensitive lichen thallus pH measurements for were also consistently more acidic than those of N-tolerant species, and closer to the observed pH optima of PME activity.

M. Silveira, A. Lumsdaine, J. White. / Supported by the National Science Foundation. MIP 91-17724

Bryophytes form an important component of northern vegetation communities. Mosses efficiently capture aerially deposited nutrients, restricting nutrient availability to the soil. Given that key ecosystem processes of northern ecosystems are nutrient-limited, understanding nutrient cycling of the moss layer is key to understanding ecosystem nutrient and C cycling in these systems. However, the role of the moss layer in regulating ecosystem-scale nutrient and C cycling, while potentially significant, is largely unknown. The aim of this thesis is to investigate the effect of the relative availability of N and P on aspects of bryophyte nutrient uptake, retention and C acquisition. The hypothesis investigated is that the availability of one nutrient will influence the demand for the other and thereby moss nutrient acquisition and retention mechanisms. To test this hypothesis, various aspects of moss nutrient cycling in response to the relative availability of N and P were investigated. As the C cycle is tightly linked to the N and P cycles, the hypothesis extended to include bryophyte C assimilation and decomposition processes of an arctic tundra. Bryophyte nutrient demand was chiefly governed by the tissue N:P ratio. Consequently, nutrient uptake, both from aerially deposited nutrients and through moss-cyanobacteria N2 fixation, and nutrient losses after a simulated rainfall event were mostly in response to the relative availability of N and P rather than the availability of one nutrient alone. This thesis provides novel evidence that ectohydric mosses have the ability to internally translocate nutrients. In conjunction with efficient nutrient capture, this trait makes mosses strong nutrient sinks which are likely to exert considerable control over ecosystem nutrient cycling. The relative availability of N and P played a role in C uptake of mosses. Through the production of recalcitrant litter and their insulating effect on soil microclimate mosses exerted an influence over ecosystem C cycling.