Abstract
Possible effects of chemical alterations in peat following re-wetting on their microbial characteristics are insufficiently known. Microbial biomass carbon (C mic), nitrogen (N mic), phosphorus (P mic) and acid phosphatase activity were investigated in re-wetted virtually undisturbed and differently degraded peatlands (Histosols) in northeast Germany to assess re-wetting effects on microbial biomass production and phosphorus (P) cycling in one growing season. The virtually undisturbed Eutri-Ombric Histosol had the largest content of microbial biomass (C mic: 2132 mg/kg, N mic: 309 mg/kg and P mic: 48 mg/kg; means of six sampling dates, upper 10 cm). Increasingly lower contents of microbial biomass were observed in the more strongly degraded peats of two Ombri-Sapric Histosols. Furthermore, the proportions of P mic as a percent of total P (P t) were smallest in the strongly degraded Ombric-Sapric Histosol (1.6% of P t) and gradually larger with better peat conservation (2.6% of P t in the moderately degraded Ombri-Sapric Histosol and 3.0% of P t in the virtually undisturbed Eutri-Ombric Histosol). The acid phosphatase activity was always greatest in May, irrespective of peat degradation. This maximum was lower for the Eutri-Ombric Histosol (2633 μg nitrophenol/(g h)) than for the two Ombri-Sapric Histosols (3963 and 3212 μg nitrophenol/(g h)). In the two degraded peats, the temporal variation in phosphatase activity was also more pronounced. Our results, in particular the higher peak phosphatase activity combined with an incorporation of P into microbial biomass, indicate that peat degradation may enhance the phosphate input to soil solution. Thus, it is concluded that modified biological P cycling could contribute to increased risks of P losses to adjacent surface water after re-wetting of degraded peats.
Published Version
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