Document Type : Research Paper
Authors
1
Assistant Professor, Forests and Rangelands Research Department, Kurdistan Agricultural and Natural Resources Research and Education Center, AREEO, Sanandaj, Iran. Email: m.haidari@areeo.ac.ir
2
Associate Prof., Forest Research Division, Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, I.R. Iran
3
Professor, Forest Research Division, Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, I.R. Iran
4
Research Expert, Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, I.R. Iran
5
Assistant Professor, Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
10.22092/ijfrpr.2024.364939.1614
Abstract
Background and Objectives: Oak decline is a critical issue in Zagros forest ecosystems. Disruptions in nutrient and water uptake, exacerbated by environmental stress, weaken trees, leading to deterioration. Soil physico-chemical characteristics significantly influence forest habitat performance. Given the spread of dieback trees in Kurdistan province, this study aimed to investigate changes in deep soil parameters associated with control stands (healthy trees) and dieback trees in the coppice stands of Marivan county, northwest Kurdistan province.
Methodology: The study was conducted in dieback (Garan) and control (Dolah Naw) forest stands in Marivan county. Within each stand, ten trees (five healthy and five dieback) were selected across north and south aspects (totaling 30 trees: 10 in the control, 20 in the dieback habitat) and numbered in 2018. Soil samples were collected on the northern side of the crown, one meter from the tree trunk at a depth of 20-40 cm (first week of August). Laboratory analyses determined moisture percentage, pH, electrical conductivity, available phosphorus, potassium, nitrogen percentage, organic carbon percentage, lime percentage, calcium, and magnesium. Principal Component Analysis (PCA) using PC-ORD 5 software was employed to assess the effect of deterioration on soil physico-chemical characteristics.
Results: Statistically significant differences were observed among the ten physical and chemical parameters across the six treatments. The highest average values for electrical conductivity (599 decisiemens/cm), moisture (13.1%), lime (13.8%), available phosphorus (13 mg/kg), and potassium (1317 mg/kg) were found in soil near trees on the northern slope of control stands. Conversely, the highest levels of organic carbon (3.75%), nitrogen (0.32%), and calcium (44.2 milliequivalents/100g) were observed in soils beneath healthy trees on the southern slope of control stands. Generally, control stands (both northern and southern aspects) exhibited higher values for most soil physico-chemical parameters, except pH and magnesium. Dieback trees showed nutrient and macronutrient deficiencies, with lower element concentrations in the soil under their crowns. PCA revealed that electrical conductivity and moisture had the highest positive loading (0.42) on the first component, while organic carbon and nitrogen loaded at 0.41. Calcium, lime, and pH loaded on the second component with positive values of 0.55, 0.53, and 0.49, respectively. PCA also indicated better soil moisture in healthy trees on the northern slope.
Conclusion: Soil physico-chemical parameters and macroelement concentrations were generally higher near trees in control stands compared to dieback-affected stands. For optimal management of dieback trees in the research area, soil enrichment and strengthening, enhanced protection measures (livestock grazing and traditional exploitation control), increased forest restoration and development in dry areas (particularly southern slopes), and sanitary cuts (branches and stems with red cracking and deterioration) are recommended.
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