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Abstract

Management of forest sites has the potential to modulate soil organic matter decomposition by chang-ing the catalytic properties of soil microorganisms within a soil profile. In this study we examined theimpact of forest management intensity and soil physico-chemical properties on the variation of enzymeactivities (-glucosidase, -xylosidase, -glucosidase, phenol oxidase, N-acetyl-glucosaminidase, l-leucine aminopeptidase, phosphatase) in the topsoil and two subsoil horizons in three German regions(Schorfheide-Chorin, Hainich-D¨un, Schwäbische Alb). The sandy soils in the Schorfheide-Chorin (SCH)showed lower ratios of the activity of carbon (C) acquiring enzymes (-glucosidase) relative to nitrogen(N) acquiring enzymes (N-acetyl-glucosaminidase + l-leucine aminopeptidase), and activity of C acquir-ing enzymes relative to phosphorous (P) acquiring enzymes (phosphatase) than the finer textured soils inthe Hainich-Dün (HAI) and Schwäbische Alb (ALB), indicating a shift in investment to N and P acquisitionin the SCH. All enzyme activities, except phenol oxidase activity, decreased in deeper soil horizons asconcentrations of organic C and total N did, while the decrease was much stronger from the topsoil to thefirst subsoil horizon than from the first subsoil to the second subsoil horizon. In contrast, phenol oxidaseactivity showed no significant decrease towards deeper soil horizons. Additionally, enzyme activitiesresponsible for the degradation of more recalcitrant C relative to labile C compounds increased in thetwo subsoil horizons. Subsoil horizons in all regions also indicate a shift to higher N acquisition, while thestrength of the shift depended on the soil type. Further, our results clearly showed that soil propertiesexplained most of the total variance of enzyme activities in all soil horizons followed by study region,while forest management intensity had no significant impact on enzyme activities. Among all includedsoil properties, the clay content was the variable that explained the highest proportion of variance inenzyme activities with higher enzyme activities in clay rich soils. Our results highlight the need for largescale studies including different regions and their environmental conditions in order to derive generalconclusions on which factors (anthropogenic or environmental) are most influential on enzyme activitiesin the whole soil profile in the long term at the regional scale