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    Modeling impacts of land uses on carbon and nitrogen contents, carbon dioxide and water effluxes of mediterranean soils
    (Hard, 2016) Erol, Ayten; Ekinci, Kamil; Akbolat, Davut; Evrendilek, Fatih
    Local alterations of land uses by policy, planning, and management decisions have global implications for coupled biogeochemical cycles. Quantification and prediction of impacts of land-use changes on carbon (C), nitrogen (N), and water (H2O) cycles are of great significance, in particular to the Mediterranean ecosystems that are already vulnerable to climate change. The present study was aimed at empirically modeling the four response variables of soil carbon (SC), nitrogen (SN) contents, carbon dioxide (CO2), and H2O effluxes as a function of the 10 predictors of land use type (forest, grassland, cropland, and their degraded states), soil organic matter, soil moisture, silt, clay and sand fractions, pH, electrical conductivity, soil microorganisms, and soil temperature. Our results showed that soil respiration rate was highest for cropland and lowest for forest (p = 0.002). Land use type was found to be the primary control and significantly related linearly to SC, SN, and soil CO2 efflux and non-linearly to all the responses. Goodness-of-fit and predictive power of the best-fit multiple non-linear regression (MNLR) models varied between 80.8% for soil CO2 efflux and 99.9% for SC, and between 67.4% for soil CO2 efflux and 99.1% for SN, respectively.
  • Küçük Resim
    Öğe
    Quantifying soil respiration in response to short-term tillage practices: a case study in southern Turkey
    (Taylor & Francis As, 2009) Akbolat, Davut; Evrendilek, Fatih; Coşkan, Ali; Ekinci, Kamil
    The study aimed at quantifying the rates of soil CO2 efflux under the influence of common tillage systems of moldboard plow (PT), chisel plow (CT), rotary tiller (RT), heavy disc harrow (DT), and no-tillage (NT) for 46 days in October and November in a field left fallow after wheat harvest located in southern Turkey. The NT and DT plots produced the lowest soil CO2 effluxes of 0.3 and 0.7 g m(-2) h(-1), respectively, relative to the other plots (P < 0.001). Following the highest rainfall amount of 87 mm on the tenth day after the tillage, soil CO2 efflux rates of all the plots peaked on the 12th day, with less influence on soil CO2 efflux in the NT plot than in the conventional tillage plots. Soil evaporation in NT (64 mmol m(-2) s(-1)) was significantly lower than in the PT (85 mmol m(-2) s(-1)) and RT (89 mmol m(-2) s(-1)) tillage treatments (P < 0.01). The best multiple-regression model selected explained 46% of variation in soil respiration rates as a function of the tillage treatments, soil temperature, and soil evaporation (P < 0.001). The tillage systems of RT, PT, and CT led, on average, to 0.23, 0.22, and 0.18 g m(-2) h(-1) more soil CO2 efflux than the baseline of NT, respectively (P <= 0.001).