Phosphatase enzyme activity and its relationship with soil properties across developmental stages of a beech forest (Asalem)
Document Type : Research Paper
Authors
1 PhD of Silviculture and Forest Ecology, Lorestan University
2 Department of Forestry, Faculty of Natural Resources, Lorestan University, Khorramabad, Iran
3 Research Division of Natural Resources, Gilan Agricultural and Natural Resources Research and Education Center (AREEO), Rasht, Iran
4 School of Forestry, Northern Arizona University, Flagstaff, Arizona, USA
Abstract
Despite the limited number of studies on soil enzyme activity across developmental stages of oriental beech (Fagus orientalis Lipsky) forests, most have focused on a narrow set of soil variables, and the simultaneous evaluation of multivariate relationships between enzyme activity and soil physical, chemical, and biological properties has received little attention. In this study, acid and alkaline phosphatase activities and their relationships with soil properties were examined across three developmental stages (initial, optimal, and decay) of an Oriental beech forest in the Asalem region, Gilan Province, northern Iran. Statistically significant differences in enzyme activity among stages were not consistently observed; however, the pattern of relationships between enzyme activities and soil properties was significantly reorganized with changes in forest developmental stage. Acid phosphatase activity was mainly associated with biological indicators and organic matter–related variables, whereas alkaline phosphatase showed closer relationships with chemical soil properties and mineral nutrient availability. Partial least squares (PLS) analysis indicated that phosphatase activity was regulated by multivariate and stage-dependent interactions among soil properties, rather than by a single dominant factor. Overall, the results of this study indicate that phosphatase activity across developmental stages of Hyrcanian beech forests cannot be adequately interpreted solely through comparisons of mean enzyme activity, because the relationships between phosphatases and soil properties vary among developmental stages. Therefore, acid and alkaline phosphatases may serve as complementary indicators for evaluating stage-dependent changes in soil phosphorus cycling and biological soil functioning in natural beech forests.
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