دوماهنامه
نوع مقاله : مقالات پژوهشی
نویسندگان
گروه مرتعداری، دانشکده منابع طبیعی و علوم دریایی، دانشگاه تربیت مدرس، نور، ایران
کلیدواژهها
عنوان مقاله English
نویسندگان English
Introduction
The Hyrcanian region, one of the richest forest ecosystems in Iran, is characterized by dense and diverse vegetation that plays a fundamental role in environmental sustainability, regulation of biogeochemical cycles, and support of biodiversity. However, in recent years, increasing human pressures and unsustainable land-use practices have led to the degradation of parts of the Caspian forest ecosystems and a substantial reduction in vegetation cover in some areas. In this context, fine roots, due to their crucial role in nutrient cycling and high sensitivity to land-use changes, together with coarse roots because of their structural functions, and soil enzymes as sensitive indicators of land management, are considered effective tools for assessing the impacts of land-use change on ecosystem functioning. Therefore, this study aimed to investigate the effects of vegetation degradation and restoration on root characteristics and soil enzyme activities in the Caspian region.
Materials and Methods
The study area is located in Kelarabad district, western Mazandaran Province, Iran. Seven different land-use types were selected in the study area, including (1) natural forest, (2) degraded forest, (3) afforestation with Alnus subcordata C. A. Mey., (4) afforestation with Acer insigne Boiss, (5) mixed afforestation with Alnus subcordata C. A. Mey.– Acer insigne Boiss., (6) afforestation with the non-native coniferous species Sequoia sempervirens (D. Don) Endl., and (7) prairie. For each vegetation type, three one-hectare sample plots (100 × 100 m) were established. Within each plot, soil samples were collected from the four corners at three depths (0–10, 10–20, and 20–30 cm) using a 30 × 30 cm sampling frame. Consequently, a total of 36 soil samples were collected from each habitat. Simultaneously, root samples were collected from the 0–30 cm depth within the same sampling units, resulting in 12 root samples per habitat, which were then transported to the laboratory. After transfer to the laboratory, root traits and soil properties were determined using standard analytical methods. All statistical analyses were performed using SPSS software (version 22). In addition, principal component analysis (PCA) was conducted using PC-ORD software to examine the relationships among vegetation cover, root characteristics, and soil enzyme activities across different soil depths.
Results and Discussion
The results of the assessment of root and soil ecochemical characteristics across the studied habitats indicated that the highest fine-root biomass and coarse root biomass occurred in the natural forest habitat. Specifically, coarse root biomass (482.38 kg ha⁻¹) and the concentrations of carbon (40.72%), nitrogen (0.51%), phosphorus (2.64%), potassium (1.56%), calcium (0.77%), and magnesium (0.42%) in fine roots were higher in the natural forest than in the other habitats. In contrast, the highest carbon-to-nitrogen ratios of both coarse roots (91.92) and fine roots (89.27) were observed in the degraded forest habitat. Regarding soil enzyme activities, the highest activities of acid phosphatase (420.58 µg PNP g⁻¹ h⁻¹), arylsulfatase (310.58 µg PNP g⁻¹ h⁻¹), and invertase (198.08 µg glucose g⁻¹ 3 h⁻¹) were recorded in the natural forest habitat at the 0–10 cm soil depth. The highest urease activity (33.84 µg NH₄⁺–N g⁻¹ 2 h⁻¹) was observed in the Alnus subcordata-restored habitat. Across all studied habitats, enzyme activities decreased with increasing soil depth, reaching their lowest values in the deeper soil layers.
Conclusion
The available evidence suggests that land degradation and land-use change, through reductions in vegetation quantity and diversity, can alter soil biological processes and lead to changes in root characteristics and soil enzyme activities. Because these biological indicators play a crucial role in regulating nutrient cycling and maintaining soil quality, understanding their responses to forest degradation and restoration is particularly important, especially in temperate ecosystems. The results of this study demonstrated that natural forest and restored forest habitats, characterized by higher soil enzyme activities, greater root biomass, and more favorable soil ecochemical conditions, exhibited superior biological performance compared with degraded and prairie habitats. Overall, the findings indicate that soil biological indicators—particularly root traits and soil enzyme activities—are sensitive and effective tools for evaluating the success of vegetation restoration and detecting the impacts of degradation in forest ecosystems of the Hyrcanian region. Therefore, the application of these indicators can provide a robust scientific basis for soil quality monitoring and the development of sustainable restoration and management programs in this region.
Acknowledgements
This work is based upon research funded by Iran National Science Foundation (INSF) under postdoctoral research project No.4038546.
کلیدواژهها English
Authors retain the copyright. This is an open access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0)
