The effects of disturbance caused by land use change on the dynamics of topsoil earthworm's activity, nematodes and carbon dioxide emission in the Nowshahr region (Case study: Gerdekoh-Safak)

Land use change in the northern part of Iran has changed the quality of soil. The aim of this study was to investigate the impacts of different kinds of land use/cover, i.e. virgin natural forest, degraded natural forest, alder plantation, sequoia plantation, improved fallow and home garden areas on soil biological characters in plain area of northern Iran. For this, 30 soil samples were taken from a depth of 0-10cm in the studied land use/covers. Density and biomass of earthworm ecological groups, soil nematodes density and the rate of carbon dioxide emission were evaluated from top soil during 4 seasons. Also, some physicochemical properties were measured at the laboratory. The maximum of earthworms density, (3 n m-2), earthworms biomass (38.76 mg m-2), nematodes density (457 in 100 g soil), and the emission of carbon dioxide (0.47 mg CO2-C gsoil−1 day−1) belonged to Alder land cover. In all the studied land use, every three groups of earthworms and nematodes had jointly the highest activity in the spring and autumn, while the highest amount of carbon dioxide emissions was recorded in the summer. PCA showed the highest positive effect the soil pH, nitrogen and nutrients with biological properties. As a result, it can be concluded that plantation with Alder species is a good way to improve biological indicators and maintain soil quality in degraded areas of forests in the northern Iran with similar condition.