State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Pla-teau, Northwest A&F University, Yangling 712100, Shaanxi, China.
College of Grassland Agriculture, Northwest A&F University, Yangling 712100, Shaanxi, China.
Ying Yong Sheng Tai Xue Bao. 2024 Jul 18;35(7):1799-1806. doi: 10.13287/j.1001-9332.202407.004.
Exploring nutrient limitation in forest soil holds significant implications for forest tending and management. However, current research on nutrient limitation status of microorganisms in plantations within the Loess Plateau remains insufficient. To investigate soil microbial nutrient limitation of plantations on the Loess Plateau, we selected plantations with different afforestation time series (15, 25, 35, and 45 years) and a pile of barren slope cropland (control) in Yongshou County, Shaanxi Province as the research objects. We analyzed the contents of soil organic matter, total nitrogen, and total phosphorus, and the activities of β-1,4-glucosidase (BG), cellobiose hydrolase (CBH), leucine aminopeptidase (LAP), β-1,4-N-acetylglucoside (NAG) and phosphatase (AP). We analyzed the soil nutrient limitation by stoichiometry and enzyme metrology. The results showed a shift in soil pH from alkaline to acidic during vegetation restoration process, and that total phosphorus exhibited a gradual decrease over the course of 0 to 25 years. Soil orga-nic matter, total nitrogen and enzyme activities exhibited an increasing trend during the same time frame. However, between 25 and 45 years of age, soil total phosphorus, soil organic matter, total nitrogen, AP and LAP gradually declined while NAG, BG, and CBH initially increased and then decreased. Notably, the values of (BG+CBH)/(LAP+NAG), (BG+CBH)/AP and (LAP+NAG)/AP in plantations were higher than the global average throughout the process of vegetation restoration. In the study area, the vector length was less than 1 and gradually increased, indicating that a progressive increase in microbial carbon limitation during the process of vegetation restoration. The vector angle exceeded 45° and exhibited an overall decreasing trend, suggesting that soil microorganisms were constrained by phosphorus (P) with a gradual deceleration of P limitation, without any nitrogen (N) limitation. The restoration of plantation resulted in significant change in soil physical and chemical properties, while the time series of afforestation also influenced nutrient limitation of soil microorganisms.
探讨森林土壤中的养分限制对于森林经营和管理具有重要意义。然而，目前对于黄土高原人工林土壤微生物养分限制状况的研究还不够充分。为了研究黄土高原人工林土壤微生物养分限制，我们选择了陕西省永寿县不同造林时间序列（15、25、35 和 45 年）的人工林和一堆荒坡耕地（对照）作为研究对象。我们分析了土壤有机质、全氮和全磷的含量，以及β-1,4-葡萄糖苷酶（BG）、纤维二糖水解酶（CBH）、亮氨酸氨基肽酶（LAP）、β-1,4-N-乙酰葡萄糖苷酶（NAG）和磷酸酶（AP）的活性。我们通过化学计量学和酶计量学分析了土壤养分限制。结果表明，在植被恢复过程中，土壤 pH 从碱性向酸性转变，全磷在 0 到 25 年期间逐渐减少。土壤有机质、全氮和酶活性在同一时期呈增加趋势。然而，在 25 到 45 年之间，土壤全磷、土壤有机质、全氮、AP 和 LAP 逐渐下降，而 NAG、BG 和 CBH 先增加后减少。值得注意的是，在植被恢复过程中，（BG+CBH）/（LAP+NAG）、（BG+CBH）/AP 和（LAP+NAG）/AP 的值始终高于全球平均值。在研究区域内，向量长度小于 1 且逐渐增加，表明在植被恢复过程中微生物碳限制逐渐增加。向量角度超过 45°且呈整体下降趋势，表明土壤微生物受到磷（P）的限制，随着 P 限制的逐渐减缓，没有氮（N）限制。人工林的恢复导致土壤物理和化学性质发生显著变化，而造林时间序列也影响土壤微生物的养分限制。
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