Nutrient dynamics and development of soil fauna in vegetated roofs with the focus on biochar amendment

The impacts of biochar amendment on the quality and quantity runoff, substrate properties soil fauna in two types experimental vegetated roofs (‘plantings’ ‘mats’) were examined during a 7-year period southern Finland. Biochar reduced leaching phosphorus (P) both plantings, which established with seeds meadow plants 100-mm-thick crushed brick mixture as growth medium, mats comprising 40-mm-thick layer pregrown vegetation 60-mm-thick mixture. nitrogen (N) only where it positively impacted plant cover. Nutrient loads declined ageing roofs, but elevated P measured following fertilization 6 years after establishment, no mitigating impact leaching. Fertilization did not affect Although nutrient from nonvegetated lower than individual rain events, difference cumulative annual between was narrowed down by high rainfall retention roofs. Neither nor organic matter content had any consistent numbers stability fauna. Despite extreme abiotic conditions animal communities unexpectedly diverse, population densities.