نوع مقاله : مقاله پژوهشی
نویسندگان
1 نویسنده مسئول، استاد، گروه علوم جنگل، دانشکده کشاورزی دانشگاه ایلام، ایلام، ایران
2 دانشیار، گروه علوم محیطزیست، واحد اهواز، دانشگاه آزاد اسلامی، اهواز، ایران
3 دانش آموخته دکتری، گروه علوم جنگل، دانشکده کشاورزی دانشگاه ایلام، ایلام، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objective: Forests play a critical role in ecosystem sustainability by regulating biogeochemical cycles and enhancing the physical, chemical, and biological properties of soils. However, conversion of forest lands to agricultural disrupts soil structure and leads to soil quality degradation. While previous studies have investigated the impact of land-use change on selected soil properties, the combined effects of abandonment duration on the Soil Quality Index (SQI) and its spatial distribution at the landscape scale in the southern Zagros forests have not been comprehensively assessed. Therefore, this study aimed to evaluate the effects of land-use type and land abandonment duration on SQI and to analyze its spatial patterns using geostatistical methods and kriging techniques in the southern Zagros forests.
Methodology: The study was conducted in the southern Zagros forests, Dezpart County, Khuzestan Province, Iran. Four land-use types were considered, including natural forest as a control and abandoned lands with durations of 3, 10, and 25 years. Soil sampling was carried out in three independent plots (3–4 ha each) per land-use type. In each plot, two randomly initiated transects were established, and four sampling points were set along each transect at 25 m intervals, resulting in a total of 96 surface soil samples (0–25 cm depth). Physical (texture, bulk density, porosity, moisture), chemical (organic carbon, total nitrogen, phosphorus, potassium, pH, electrical conductivity, cation exchange capacity), and biological (respiration, microbial carbon) properties were measured. SQI was calculated using standard scoring functions, factor analysis for weight determination, and a cumulative weighted index approach. The spatial structure of SQI was analyzed using variograms and kriging methods in GIS, and the most appropriate interpolation method for each land-use type was selected based on model accuracy (RMSE). Statistical analyses were conducted to compare SQI across land-use types at a 95% confidence level (α = 0.05).
Results: Land-use type significantly influenced SQI (p < 0.05), with the highest value observed in natural forest (0.63 ± 0.006) and the lowest in recently abandoned (0.26 ± 0.006). Soil quality progressively improved with increasing abandonment duration, with 25-year abandoned lands showing significantly higher SQI compared to short-term abandoned sites. Variogram analysis indicated that the linear model best described SQI spatial structure in natural forests, the exponential model fitted short- and long-term abandoned lands (10 and 25 years), and the spherical model best represented recently abandoned lands. Accuracy assessment revealed that simple kriging achieved the highest precision for natural forest (RMSE = 0.97) and long-term abandonment (RMSE = 1.01), whereas ordinary kriging performed better for short-term abandonment (RMSE = 1.18) and recently abandoned lands (RMSE = 1.57). The resulting spatial maps highlighted heterogeneous patterns of soil quality across the study area.
Conclusion: The findings demonstrate that forest land-use change and land abandonment duration exert significant effects on soil quality, with longer abandonment periods leading to gradual improvement. These results can inform land abandonment planning, forest restoration, and the identification of low-quality soil areas for sustainable natural resource management.
کلیدواژهها [English]
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