ABSTRACT
The hardness of construction materials determines its resistance to pressure from roots and weathering, although all building materials decay eventually. The vegetation invading walls and paving responds to low moisture and nutrients by producing stunted plants with low biomass, fertility, and productivity. Although stonework is challenging for invading organisms, it provides opportunities for those species that are adapted to the relatively harsh conditions, and for management to enhance biodiversity. Humans also disperse organisms by transportation in building materials, on vehicles and in their slipstreams, or by direct transplantation. Pollutants such as de-icing salts alongside roads, and many vehicular pollutants harm organisms and reduce plant biomass. Stonework can feature a surprising diversity of organisms, and offers opportunities for enhancement, perhaps balancing trends in the expansion of impervious surfaces. Stonework can provide important habitats for a variety of organisms.
