Suše i proces aridizacije kao faktor degradacije zemljišta na području Deliblatske peščare
Droughts and the Process of Aridification as Soil Degradation Factor in Deliblato Sands
AuthorMansour, Yousef Ali Bohajar
Committee membersĐurđević, Vladimir
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In this doctoral dissertation, the research of the influences of droughts and the process of aridification have been conducted on Deliblato Sands area’s sensitivity, as a Special nature reserve, especially from the aspect of land degradation, the condition of vegetation cover and sustainable management of these ecosystems. Research included two groups: climatological studies (for the period 1980-2010) and the studies of soil. Within climatological studies, the focus was on climate factors most often used in the research of land degradation. This primarily refers to precipitation (P), temperature (T), wind (W) and their extremes, potential evapotranspiration (PET), standardized precipitation index (SPI for 1. 2. 3. 6 and 12 monts ) and aridity indices (AI and BGI). Soil studies (31 pedological profiles) comprised of field and laboratory research that defined morphological, physical and chemical properties. Based on these researches, described and selected soils were grouped i...nto four categories, according to WRB classification: group I – Protic Arenosol (Calcaric), group II – Arenosol (Haplic, Calcaric), group III – Chernozem (Arenic), group IV – Glaysol (Calcaric, Arenic). The results of soil degradation of Deliblato Sands, amongst other, have enabled the marking off of three texture classes which belong to different categories of erodibility: highly erodible soils with 56.17% (sand), medium erodible soils with 41.27% (clay sand) and low erodible soils with 36.62% (sandy clay). Soil sensitivity to the process of wind erosion, in model RWEQ, is defined by the participation of erodible fraction (EF) that contains soil particles <0.84 mm. The erodible fraction depends on physical and chemical soil properties, including the contents of sand, dust and clay, the contents of organic matter and CaCO3 in surface level 0-25 mm. Using the same model, the soil crust factor (SCF) is determined which reflects the changes of abrasive surface resistance, when the surface is modified by precipitation. The analytical data of certain soil properties were processed using mathematicalstatistical methods (Statistical multivariate package): variance analysis (F-test and LSD-test applied (P<0.05)), regression and correlation analysis, cumulative frequency analysis. All statistical analyses were conducted for the selected groups of soils (by WRB method) and for soils sorted out according to the groups of vegetation. The statistical analyses were performed using a statistical program Statgraphics Plus. The results were processed by descriptive statistics, correlation and regression analyses, as well as variance analysis (ANOVA test). Contemporary statistical methods have been applied in the analysis of geospatial data on the soil sensitivity of Deliblato Sands and their mutual dependence, which have made the analysis of data on raster sets possible. The problems of land degradation, as a primary element of nature, represent significant problems of environment. Among numerous problems related to the processes of degradation, soil erosion is a dominant process, especially in semi-arid and arid areas in which water acts as a limiting factor, conditioning ecosystem productivity and stability. In the area of Deliblato Sands which is characterized by specific land creations and arid and semi-arid conditions during most of year, the problems of land degradation are related to the process of wind erosion. The results of climatological and pedological research enabled the performance of statistical and geostatistical analyses of certain parameters. The given results, along with the analyses of vegetation and management system, allowed for the carrying out of integrated GIS analyses and assessments of soil sensitivity of Deliblato Sands in regards to land degradation, using MEDALUS model (Mediterranean Desertification AndLand Use). The application of the model included a selection of indicators which best characterize soil quality (in regard to soil erodibility), climate quality (with regard to erosivity), vegetation quality (in regards to protection) and the quality of area management. The assessment of the above-mentioned four indices of quality and the final index of sensitivity of Deliblato Sands was conducted based on algorithms, which provided synthesis cards for each index of quality. Based on these results and from the aspect of sensitivity, the area of Deliblato Sands is divided into four classes: class N – soils are not endangered, it covers 3.9 ha or 0.01% of territory; class P – potentially endangered, it covers 186.15 ha or 0.55% of territory; class F – fragile, divided into three subclasses: F1 – 843.69 ha or 2.50% of territory, F2 – 2532.63 ha or 7.49% of territory and F3 – 11217.39 ha or 33.19% of territory; class C – critical, divided into three subclasses: C1 – 648.18 ha or 1.92% of territory, C2 – 9943.44 ha or 29.42% of territory and C3 – 8422.93 ha or 24.92% of territory. These results also show that 99.44% of Deliblato Sands area belongs to classes “fragile” and “critical”, emphasizing the spread and intensity of danger that comes from soil degradation of the area.