Faculty of Natural Resources & Marine Sciences, Tarbiat Modares University, 46417-76489, Noor, Mazandaran, Iran.
Department of Sciences and Forest Engineering, Sari Agricultural Sciences and Natural Resources University, Mazandaran, Iran.
Sci Total Environ. 2024 Jun 10;928:172218. doi: 10.1016/j.scitotenv.2024.172218. Epub 2024 Apr 4.
In natural habitats, especially in arid and semi-arid areas that are fragile ecosystems, vegetation degradation is one of the most important factors affecting the variability of soil health. Studying physicochemical and biological parameters that serve as indicators of soil health offers important information on the potential risk of land degradation and the progression of changes in soil performance and health during recovery periods. This study specifically examines the impact of vegetation degradation on soil health indicators and the duration needed to improve the physical, chemical, and biological parameters in a semi-arid mountainous area site types with the dominance of Quercus macranthera Fisch & C.A. Mey and Carpinus orientalis Miller in northern Iran. In different years (2003, 2013, and 2023), litter and soil samples (at depths of 0-10, 10-20, and 20-30 cm) were collected in different types of degraded sites. Additionally, in 2023, a non-degraded site was chosen as a control and similar samples were collected. A total of 48 litter (12 samples for each of the study site types) and 144 soil (4 study site types × 3 depths × 12 samples) samples were collected. In order to investigate the spatial changes of soil basal respiration (or CO emission), which is involved in global warming, from each site type, 50 soil samples were taken along two 250-meter transects. The findings showed that litter P and Mg contents in the non-degraded site were 1.6 times higher than in degraded site types (2003). Following vegetation degradation, soil fertility indicators decreased by 2-4 times. The biota population was lower by about 80 % under the degraded site types (2003) than in the non-degraded site, and the density of fungi and bacteria in the degraded site types was almost half that of the non-degraded site types. Geostatistics showed the high variance (linear model) of CO emissions in areas without degradation. In addition, vegetation degradation significantly reduced soil carbon and nitrogen mineralization. Although soil health indicators under the degraded vegetation have improved over time (30 years), results showed that even thirty years is not enough for the full recovery of a degraded ecosystem, and more time is needed for the degraded area to reach the same conditions as the non-degraded site. Considering the time required for natural restoration in degraded site types, it is necessary to prioritize the conservation of vegetation and improve the ecosystem restoration process with adequate interventions.
在自然栖息地中，特别是在脆弱生态系统的干旱和半干旱地区，植被退化是影响土壤健康变异性的最重要因素之一。研究作为土壤健康指标的理化和生物学参数，可以提供有关土地退化潜在风险以及土壤性能和健康在恢复期间变化的重要信息。本研究专门研究了植被退化对土壤健康指标的影响，以及在伊朗北部以栓皮栎和麻栎占优势的半干旱山区不同类型退化地，提高土壤物理、化学和生物学参数所需的时间。在不同年份（2003 年、2013 年和 2023 年），在不同类型的退化地采集了凋落物和土壤样品（深度为 0-10、10-20 和 20-30cm）。此外，在 2023 年，选择了一个非退化地作为对照，并采集了类似的样品。共采集了 48 个凋落物（每个研究地类型 12 个样本）和 144 个土壤（4 个研究地类型×3 个深度×12 个样本）样品。为了研究从每个地类型采集的土壤基础呼吸（或 CO 排放）的空间变化，该变化涉及全球变暖，从每个地类型采集了 50 个土壤样品，沿两条 250 米的样带进行采集。结果表明，非退化地的凋落物 P 和 Mg 含量比退化地类型高 1.6 倍（2003 年）。在植被退化后，土壤肥力指标下降了 2-4 倍。退化地类型下的生物种群减少了约 80%（2003 年），而退化地类型的真菌和细菌密度几乎是未退化地类型的一半。地统计学显示无退化地区 CO 排放的高方差（线性模型）。此外，植被退化显著降低了土壤碳和氮的矿化作用。尽管退化植被下的土壤健康指标随着时间的推移（30 年）有所改善，但结果表明，即使 30 年也不足以使退化生态系统完全恢复，退化区需要更多时间才能达到与未退化区相同的条件。考虑到退化地类型自然恢复所需的时间，有必要优先保护植被，并通过充分的干预来改善生态系统恢复过程。
