The Fertile Rock: Productivity and erosion in limestone solution hollows of the Burren, Co. Clare

The Burren, a region of extensive limestone pavement, is home to numerous solution hollows. These pools typically contain a characteristic black deposit, made up of microbial communities—mainly cyanobacterial—and inorganic mineral matter. A minority contain a red layer of the chlorophyte Haematococcus pluvialis, while others contain macroscopic Nostoc cyanobacterial colonies. This study examines the productivity and growth patterns of these communities and addresses their potential as bio-erosive agents on limestone substrates in a field experiment involving 72 pools. It investigates the role of organic enrichment in producing Haematococcus blooms, and measures concentrations of various pigments in pool communities over a 12-month period. A minimum production rate of 66g/m2/ year dry organic mass was estimated and a minimum limestone denudation rate of 71mm per 1000 years. The results indicate that solution hollows are sites of elevated biomass production and erosion, and that the cyanobacterial deposit is involved in soil production and the conversion of limestone pavement into a habitat suitable for vascular plants.