Spatial distribution of soil water repellency in a grassland located inLithuania

Risultato della ricerca: Other


Soil water repellency (SWR) it is recognized to be very heterogeneous in time in space and depends on soiltype, climate, land use, vegetation and season (Doerr et al., 2002). It prevents or reduces water infiltration, withimportant impacts on soil hydrology, influencing the mobilization and transport of substances into the soil profile.The reduced infiltration increases surface runoff and soil erosion. SWR reduce also the seed emergency andplant growth due the reduced amount of water in the root zone. Positive aspects of SWR are the increase of soilaggregate stability, organic carbon sequestration and reduction of water evaporation (Mataix-Solera and Doerr,2004; Diehl, 2013). SWR depends on the soil aggregate size. In fire affected areas it was founded that SWR wasmore persistent in small size aggregates (Mataix-Solera and Doerr, 2004; Jordan et al., 2011). However, littleinformation is available about SWR spatial distribution according to soil aggregate size. The aim of this workis study the spatial distribution of SWR in fine earth (<2 mm) and different aggregate sizes, 2-1 mm, 1-0.5 mm,0.5-0.25 mm and <0.25 mm. The studied area is located near Vilnius (Lithuania) at 54 42’ N, 25 08 E, 158masl. A plot with 400 m2 (20 x 20 m with 5 m space between sampling points) and 25 soil samples were collectedin the top soil (0-5 cm) and taken to the laboratory. Previously to SWR assessment, the samples were air dried.The persistence of SWR was analysed according to the Water Drop Penetration Method, which involves placingthree drops of distilled water onto the soil surface and registering the time in seconds (s) required for the dropcomplete penetration (Wessel, 1988). Data did not respected Gaussian distribution, thus in order to meet normalityrequirements it was log-normal transformed. Spatial interpolations were carried out using Ordinary Kriging. Theresults shown that SWR was on average in fine earth 2.88 s (Coeficient of variation % (CV%)=44.62), 2-1mm1.73 s (CV%=45.10), 1-0.5 mm 2.02 s (CV%=93.75), 0.5-0.25 mm 3.12 s (CV%=233.68) and in <0.25 mm 15.54mm (CV%=240.74). This suggests that SWR persistence and CV% is higher in small size aggregates than in thecoarser aggregate sizes. The interpolated maps showed that in fine earth SWR was higher in the western part ofthe studied plot and lower in the central area. In the 2-1 mm aggregate size it was higher in the southwest andlower at north and northwest area. In the 1-0.5 mm aggregate size it was lower in the central area and higher in thesouthwest. In the 0.5-0.25 mm aggregate size it was higher in the west part and lower in the north of the plot and.In the <0.25 mm no specific pattern was identified and the SWR was heterogeneously distributed. This suggeststhat the spatial distribution of SWR is very different according to the aggregate size. Future studies are needed inorder to identify the causes and consequences of such dynamic.AcknowledgementsThe authors appreciated the support of the project “Litfire”, Fire effects in Lithuanian soils and ecosystems(MIP-048/2011) funded by the Lithuanian Research Council
Lingua originaleEnglish
Numero di pagine1
Stato di pubblicazionePublished - 2014

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