Original article Influence of seasons and land-use practices on soil microbial activity and metabolic diversity in the “Montado ecosystem” Dalila Costa a, * , Helena Freitas b , José Paulo Sousa a a University of Coimbra, Department of Life Sciences, IMAR e CMA, Apartado 3046, 3001-401 Coimbra, Portugal b University of Coimbra, Department of Life Sciences, Centre for Functional Ecology, Apartado 3046, 3001-401 Coimbra, Portugal article info Article history: Received 18 May 2013 Received in revised form 2 August 2013 Accepted 15 August 2013 Available online 29 August 2013 Handling editor: Bryan Griffiths Keywords: Land-use Montado ecosystem Soil enzymes N-Mineralization Nitrification Biolog abstract The “Montado ecosystem” is important both economically and ecologically; this ecosystem is dominated by cork and holm oak trees (Quercus suber L. and Quercus rotundifolia Lam. respectively) combined with a rotation of crops/fallow/pastures. Diverse management strategies, deviating from the sustainable use of the ecosystem, have been implemented, from which arise some extreme situations of over-use or abandonment. To evaluate the effects of different soil use and management, namely extensive cropping, intensive pasture and abandonment, in the activity of soil microorganisms, dehydrogenase, acid phos- phatase, b-glucosidase and urease activities, N-mineralization and nitrification rates were measured in different land-use practices, in different seasons (winter, spring and autumn). Also, the potential metabolic diversity was evaluated by analysis of community-level physiological profiles (CLPPs). Seasonal effects were evident with maximum activity occurring in rainy seasons (winter and autumn) and lower substrate utilization in winter. Significant correlations between most microbial parameters and soil water content reflect this seasonal effect. Although showing mainly a seasonal change, microbial parameters were able to distinguish the abandoned area, with a general low activity and differential exponential rates in the use of several substrates, such as amino acids, miscellaneous and polymers, probably associated with changes in organic matter quality. Ó 2013 Elsevier Masson SAS. All rights reserved. 1. Introduction The “Montado ecosystem” located in South Portugal is an agro- silvo pastoral system, dominated by cork and holm oak trees (Quercus suber L. and Quercus rotundifolia Lam.) combined with a rotation of crops/fallow/pastures. This ecosystem has an economic importance due to cork production, cattle raising and agriculture production [1] and is ecologically significant since it sustains a high biodiversity [2]. Several management strategies, deviating from the ancestral sustainable use of the land, have being implemented over the years, from which arise some extreme situations of over utili- zation or abandonment [1]. These land-use changes are leading to a modification of the ecosystem, reflected in soil quality degradation. Soil microorganisms fulfil important ecosystem functions, intervening in soil biological processes, mainly in organic matter decomposition and nutrient cycling, thus maintaining soil quality. The diversity of functions performed by microbial communities is essential to maintain the soil multi-functionality [3]. These biological functions, mediated by enzymes, are associated with the microbial capacity to use several organic compounds as substrates. Therefore, enzymatic activity and measures of metabolic diversity represent the microbial activity, and are indicators of soil quality changes due to several natural and anthropogenic drivers, e.g., pollution, soil management practices and land-use changes [3e5]. Since microbial activity includes various metabolic processes, several enzyme activities involved in main biogeochemical cycles, such as C, N and P should be determined [6]. From the plethora of soil enzymes, dehydrogenase (DHA), acid phosphatase, b-glucosi- dase and urease activities have been widely used as response in- dicators of soil microbial communities to several environmental pressures. The activity of these enzymes has been found to be sensitive to seasonal and management effects in the Mediterranean area. Some studies, carried out in this region, demonstrated that the highest microbial activity occurred in spring [7]. In their study, Sardans and Peñuelas [8] found higher phosphatase, urease and b- glucosidase activities in spring when compared with autumn. Management effects were also observed with lower enzyme ac- tivity found in abandoned sites [9]. Nitrogen turnover parameters, like N-mineralization and nitri- fication rates, are important soil microbial processes contributing * Corresponding author. Tel.: þ351 239855760; fax: þ351 239855789. E-mail address: dalila.costa@iav.uc.pt (D. Costa). Contents lists available at ScienceDirect European Journal of Soil Biology journal homepage: http://www.elsevier.com/locate/ejsobi 1164-5563/$ e see front matter Ó 2013 Elsevier Masson SAS. All rights reserved. http://dx.doi.org/10.1016/j.ejsobi.2013.08.003 European Journal of Soil Biology 59 (2013) 22e30