Impacts of changes in land use/cover on soil microbial and enzyme activities

•The type of land use/cover affects soil microbial and enzyme activities.•Alder plantation improved soil chemical, biological and biochemical properties.•Soil microbial biomass C increased under sequoia plantation and natural forest.•Biological properties were more affected by variations in soil C and N and available nutrients.

Microbial and enzyme activities are increasingly being recognized as sensitive indicators of soil quality. This study aims to determine the impacts of different kinds of land use/cover, i.e. virgin natural forest (VNF), degraded natural forest (DNF), alder plantation (AP), sequoia plantation (SP), improved fallow (IF) and home garden (HG) areas on soil properties in northern Iran. Five composed samples per land use/cover were taken from the top 10 cm of the soil.Soil microbial respiration was found to be in the ranked order of AP > VNF > HG > DNF > IF ≈ SP areas, being more than one-and-a-half-fold under AP compared with SP. The values of microbial biomass carbon were almost two times higher under SP ≈ VNF than under IF ≈ HG areas. Microbial biomass nitrogen was found to be significantly higher under AP ≈ VNF than in the other kinds of land covers. AP ≈ VNF significantly increased the activities of urease and acid phosphatase, whereas greater activities of invertase occurred in AP ≈ VNF ≈ SP sites. Arylsulphatase activity was significantly higher to be significantly higher under AP in comparison with VNF > HG > DNF > SP > IF areas. As a conclusion, alder (Alnus subcordata C. A. Mey.) plantation improved the soil quality to levels similar to natural forest ecosystems. This research recommends the preservation of natural forests to increase soil quality and a plantation with suitable native broad-leaved species and forestation plan management to rehabilitate degraded natural forests.