[automatically translated] The objective of this work was to evaluate, in different forest soils and in controlled laboratory conditions, the impact of the warming fire and subsequent shutdown seawater on the dynamics of extractable C and kinetics of respiration. To this end, in homogeneous soil and climate area, were selected 4 different soils under forest species: red gums (EC), E. occidentalis (EO), Pinus halepensis (PH) and Cupressus sempervirens (CS). The soil samples were heated at 25 (control), 160 and 380 ° C for 30 minutes and humidified at 50% of field capacity with seawater or distilled water (control), thus obtaining 6 distinct treatments for each soil. Samples (n = 4) were then incubated at 25 ° C for 77 days, during which, in about one week distance, They were determined the respiration rate (CO2 production) and the removable C in K2SO4 0.5M (Cextr). The heating of the soil, which is at 160 to 380 ° C, it immediately caused a significant increase of Cextr that, according to the forest species, is fluctuated from 130 (CS) to 470% (EC and PH), compared to 25 ° C. During the incubation, Cextr is reduced abruptly in soils humidified with distilled water, until reaching the end lower values of those pre-heating, while in the humidified soils with marine water the Cextr decrease was slower and less drastic, with to higher final values of those pre-heating. The C potentially mineralizable (C0) and the constant of its mineralization rate (k) were determined by fitting the CO2 production data with the model Ct = CS + C0 e-kt, where Ct is the C mineralized after t days, and CS is a pool of more easily degradable C C0. The soils incubated at 25 ° C and humidified with sea water, compared with the control, showed in time lower average values of C mineralized (C0 k), suggesting that the sea water inhibited the respiratory activity probably due of a osmotic stress. On the other hand, in the soil is heated to 160 to 380 ° C, the derived parameters (CS, C0, k) have not shown a unique trend for all forest species. In any case, it detects a combined biocidal effect due to the synergy between high temperature (380 ° C) and osmotic stress. Furthermore, especially at 160 ° C, while in some soils respiratory activity seems inhibited by osmotic stress caused by the sea water, in others this inhibition ι zero or negative (activation). From these first results show that switching off forest fires with seawater puσ amplify the damage of soil quality due to the fire itself, with potential negative repercussions in global change.
|Number of pages||1|
|Publication status||Published - 2009|