Grassland afforestation promotes carbon sequestration at the expense of consuming water resources. With the development of forest plantations, the increase in aboveground biomass could aggravate the limitations of soil moisture and nutrients, and thus alter understory succession. However, it is unclear how these changes influence the mineral element cycle in plant‐soil systems. We conducted a four‐year experiment in young, middle‐aged, and mature stands in a larch plantation and investigated how stand development affects macronutrient (K, Ca, and Mg) and micronutrient (Na, Fe, and Zn) concentrations in soils and leaves of larch and understory plants. Our results showed that as stand age increased, soil moisture and soil pH decreased. The reduced soil moisture directly led to an increase in soil total sodium (Na) and potassium (K) concentrations. There was no significant difference in mineral element concentrations in the larch leaves among the three stands. However, the understory vegetation in the mature stands had higher foliar K concentration but lower foliar Na concentration than in the young stands. Furthermore, plant calcium (Ca) concentration was positively correlated with plant K:Na ratio. The stoichiometric coupling between leaf [Ca] and K:Na ratio became tighter with increased stand age, which could improve the tolerance of plants to drought and soil salinization. Our findings suggested that water limitation and soil salinization caused by grassland afforestation intensified with increased stand age. To adapt to these stresses, understory vegetation often shifts to species with high K but low Na leaf concentrations.

中文翻译：

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林分发育引起的干旱和盐碱化胁迫改变了落叶松人工林的矿质元素循环

草原绿化以消耗水资源为代价促进了碳固存。随着人工林的发展，地上生物量的增加可能加剧土壤水分和养分的局限性，从而改变林下植被的演替。但是，尚不清楚这些变化如何影响植物-土壤系统中的矿质元素循环。我们在落叶松人工林的幼林，中年林和成熟林中进行了为期四年的实验，研究了林分发育如何影响土壤和土壤中常量养分（K，Ca和Mg）和微量养分（Na，Fe和Zn）的浓度。落叶松和林下植物的叶子。我们的结果表明，随着林龄的增加，土壤水分和pH值降低。减少的土壤湿度直接导致土壤总钠（Na）和钾（K）浓度增加。在三个林分之间，落叶松叶片中的矿质元素浓度没有显着差异。然而，与幼龄林相比，成熟林下的地下植被叶面钾含量较高，而叶面Na含量较低。此外，植物钙（Ca）浓度与植物钾：钠比呈正相关。叶片[Ca]和K：Na比之间的化学计量耦合随着林分年龄的增加而变得更紧密，这可以提高植物对干旱和土壤盐碱化的耐受性。我们的发现表明，随着林分年龄的增长，由草地绿化引起的水分限制和土壤盐碱化加剧。为了适应这些压力，林下植被通常转移到钾含量高但钠叶含量低的物种。