Soil enzyme activity and stoichiometry in relation to different land uses in the Mediterranean area

Mowing and grazing are among the most common grassland management practices, and the frequency and intensity with which they are applied can reduce soil nutrient availabilities. These alterations may drive microorganisms to increase the production of enzymes associated with the acquisition of limiting nutrients. This study aimed to investigate how different land uses—and their associated management practices—affect microbial strategies for soil nutrient acquisition and ecosystem responses to nutrient limitation. Thus, in the Matese mountain (Southern Italy), adjacent areas under different land uses (forest-FO, meadow-ME, pasture-PA) were selected, and the soils sampled at four times along the year (T1, T2, T3 and T4), corresponding to specific management practices in ME and PA. Total soil nutrient (seven macro- and four micronutrient) concentrations, and twelve soil enzymatic activities involved in carbon, nitrogen, and phosphorus acquisition by the microbial community were analyzed. Enzyme stoichiometric ratios (ECN, ECP,ENP) as well as length and angle of a vector combining ECN and ECP were calculated to assess soil nutrient acquisition strategies. ECN and ECP values highlighted a greater microbial investment in nitrogen and phosphorus acquisition across all land uses, whereas the higher vector length value observed at T2 and T3 in PA and at T3 in ME suggested increased microbial allocation toward carbon acquisition. ENP and the vector angle values highlighted a greater phosphorus acquisition in FO, nitrogen in PA, and balanced nitrogen and phosphorus acquisition in ME. These patterns suggest that land use and management practices influence microbial resource-allocation strategies and ecosystem responses to nutrient limitation by altering extracellular enzyme production. Our findings further show that practices such as annual mowing and low grazing pressure have helped preserve the balance of soil microbial nutrients, while also indicating the value of enzymatic stoichiometry as an effective useful approach for understanding microbial adaptation to nutrient limitation and ecosystem functioning under different land uses.