Conversion of cropland to natural vegetation boosts microbial and enzyme activities in soil

The trends of enzyme activities and litter chemistry after abandonment of arable soil and succession of natural vegetation were studied in a deciduous forest zone (Moscow region, Russia). The Luvic Phaeozem chronosequence included an arable field, 3 fields with increasing abandonment periods (7, 11, 35 years), and the soil under natural forest as a reference site (never used for cropland). The activities of four hydrolytic enzymes (β-glucosidase, cellobiohydrolase, β-galactosidase, chitinase) in the topsoil (0–5 cm) were compared with chemical functional groups of plant litter identified by 13C NMR spectra. The total enzyme activity increased 5-fold during 35 years of postagricultural restoration of arable soil. The share of C-cycle enzymes with “narrower” substrate specificity (cellobiohydrolase and chitinase) increased during 35 years from 19% to 42% of the total enzyme pool. We explain this gain by the increase in the diversity and recalcitrance of organic compounds in the plant litter from cropland to natural forest. Aromaticity index of plant litter built up remarkably: from 0.11 in the young abandoned land to 0.14–0.15 in the 35-year abandoned land and the reference site. The share of enzymes with a “narrower” substrate specificity correlated closely with the portions of aryl C, O-aryl C, and carbonyl C functional groups in plant litter. Accordingly, the succession of natural vegetation on abandoned cropland leads to strong diversification of the plant litter composition and a corresponding production of soil enzymes with “narrower” substrate specificity. © 2020

Ovsepyan L.1, 2 , Kurganova I.1 , Lopes De Gerenyu V. , Kuzyakov Y. 3, 4
Elsevier B.V.
  • 1 Institute of Physicochemical and Biological Problems of Soil Science, Russian Academy of Sciences, Pushchino, Moscow Oblast 142290, Russian Federation
  • 2 University of Koblenz-Landau, Institute for Environmental Sciences, Landau, 76829, Germany
  • 3 Dept. of Soil Science of Temperate Ecosystems, Dept. of Agricultural Soil Science, University of Göttingen37073, Germany
  • 4 Agro-Technological Institute, RUDN University, Moscow, 117198, Russian Federation
Ключевые слова
Hydrolytic enzyme activity; Luvic Phaeozem; Organic and microbial carbon; Plant litter 13C NMR spectra; Postagricultural succession; Substrate specificity
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