Smith V R, Steenkamp Marianna
Department of Botany and Genetics, University of the Orange Free State, 9301, Bloemfontein, South Africa.
Oecologia. 1992 Nov;92(2):201-206. doi: 10.1007/BF00317365.
The densities, diets and habitat preferences of the soil macrofaunal species on sub-Antarctic Marion Island (47°S, 38°E) are described. Their role in N cycling on the island is assessed, using a mire-grassland community as an example. Primary production on the island is high and this leads to a substantial annual requirement of nutrients by the vegetation. This requirement must almost wholly be met by mineralization of nutrient reserves in the organic matter. Rates of peat nitrogen mineralization mediated by microorganisms alone are much too low to account for rates of N uptake by the vegetation. Although soil macroinvertebrates, and bacteria represent a very small fraction of the total N pool, their interaction accounts for most of the peat N mineralization, as indicated by the amounts of inorganic N released into solution in microcosms. Extrapolation of the microcosm results shows that the soil macrofauna (mainly earthworms) stimulate the release of enough N from the mire-grassland peat to account for maximum N mineralization rates calculated from temporal changes in peat inorganic N levels and plant uptake during the most active part of the growing season. Considering that large numbers of mesoand microinvertebrates occur and must also contribute to nutrient mineralization, the soil faunal component is clearly of crucial importance to nutrient cycling on Marion Island. This is probably true of all sub-Antarctic islands.
本文描述了亚南极马里恩岛（南纬47°，东经38°）土壤大型动物区系物种的密度、食性和栖息地偏好。以沼泽草地群落为例，评估了它们在该岛氮循环中的作用。该岛的初级生产力很高，这导致植被每年对养分有大量需求。这一需求几乎完全必须通过有机质中养分储备的矿化来满足。仅由微生物介导的泥炭氮矿化速率远低于植被对氮的吸收速率。尽管土壤大型无脊椎动物和细菌在总氮库中所占比例很小，但如微观世界中释放到溶液中的无机氮量所示，它们的相互作用占泥炭氮矿化的大部分。微观世界结果的外推表明，土壤大型动物区系（主要是蚯蚓）刺激沼泽草地泥炭释放足够的氮，以解释根据生长季节最活跃时期泥炭无机氮水平和植物吸收的时间变化计算出的最大氮矿化速率。考虑到大量中型和微型无脊椎动物的存在，它们也必定对养分矿化有贡献，土壤动物区系成分显然对马里恩岛的养分循环至关重要。所有亚南极岛屿可能都是如此。
