Seasonal Activity of Soil Peroxidase in Drained Swamp Pine Forests of Western Siberia: Systemic-Ecological Analysis

Abstract

We studied a mesotrophic swamp drained 25 years ago in the northern part of the Ob’ River basin (56°23′710″ N, 84°34′043″ E). In peat soils (0–30 cm layer), the weighted average of peroxidase activity for the season (base level) constituted 14.4, 21.9, and 70 units (mL I/g abs. dry soil per 2 min) in the areas subjected to weak, moderate, and intensive drainage, respectively. Second-order parabola is the most adequate function of the main trend of development of seasonal fluctuations in peroxidase activity. Numerical values and signs of the parabolic trend parameters showed that the average peroxidase activity decreased from June to October weekly by 4.4, 7.6 and 15.2 units with weekly average acceleration by 0.31, 0.59 and 1.54 units in the mode of weak, moderate, and intensive drainage, respectively. The seasonal wave of peroxidase activity relative to the baseline level was characterized by a June increase in growth rates with a maximum in the layer of 0–10 cm. In July, there was a decrease in the growth rate according to the depth of reclamation: in the modes of weak and moderate drainage, the process embraced the entire soil profile in August; in case of intensive drainage, in October. The enzyme activity significantly and positively correlated with the soil volumetric water content and pH, negatively correlated with redox potential, and displayed multidirectional relationship with the soil temperature. Environmental conditions acted as mutually replacing parameters when assessing their contribution to the seasonal dynamics of peroxidase, creating the effect of interchangeability of environmental gradients. Canonical determination indices approximated the cumulative impact of the discussed set by 52–74%, depending on the depth of reclamation. Canonical weights showed that the hydrothermal regime was the main factor, regulating the seasonal activity of peroxidase: according to canonical correlations, temperature was the main factor under the conditions of weak drainage, moisture was the main factor under the conditions of intensive drainage, and both moisture and temperature were important factors under the conditions of moderate drainage. The peroxidase activity and the depth of humification in peat soils of different degrees of drainage were interrelated in 87% of cases.