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The type of SI operating within the genus was considered to be best explained by gametophytic self-incompatibility (GSI) with interspecific variation in its phenotypic expression. The implications of these findings are discussed in relation to SI in the Pleurothallidinae and conservation strategies for Restrepia and related genera.

The objective of this paper was to investigate the options for the sustainable development of the Northern Ireland energy supply system, reducing greenhouse gas emissions. Particular factors which must be considered centre around the isolation of the system, the prospect of a new gaspipeline and electrical interconnector to the rest of the U.K., and the re-establishment of an electrical interconnector to the Republic of Ireland. The study has relevance for all similar isolated or island systems, which have particular problems because they tend to be relatively small in size, and their isolation means that inter-connection with their neighbours is either weak or non-existent. Because of this, they have to carry greater spare capacity than would normally be the case, with consequent e$ciency and cost penalties.

Metadata onlyThe post-war decline in the area and diversity of neutral meadows in Britain, resulting from agricultural intensification, has prompted schemes to restore and create new habitats. Their success relies on understanding the relations between soil fertility and species diversity. We have investigated these relations, using multivariate analysis, in 28 semi-natural meadows and eight artificially created urban meadows. Mineralizable nitrogen was the most important soil characteristic in the semi-natural sites; the more N the soil contained the fewer were the species characteristic of traditional meadows. Both potassium and total magnesium favoured diversity, perhaps because their deficiency in many traditionally managed meadows jeopardizes the survival of broad-leaved species in competition with grasses. Available lead, at sub-lethal concentrations and measured as a Pb:Ca ratio, appeared to favour diversity in the semi-natural sites, possibly by inhibiting the uptake of P by competitive grasses and allowing the less competitive species associated with diversity to flourish. The main differences between the soils of the artificial and the semi-natural meadows were that the former contained more extractable P and less mineralizable N and organic matter. It seems that large soil phosphorus concentrations may be the main reason why relatively few species colonize or survive in grassland on many urban soils

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