Over the past few decades the Arctic has warmed up more than the lower latitudes. Soil organic carbon (SOC) in the Arctic is vulnerable to climate change, and carbon dioxide (CO₂) produced via SOC decomposition can amplify atmospheric temperature increase. Although SOC composition is relevant to decomposability, studies on its compositional changes with warming are scarce, particularly in the Arctic. Therefore, we investigated the responses of SOC and the bacterial community to climate manipulation under Cassiope and Salix heath vegetation communities in permafrost‐affected soil in Zackenberg, Greenland. After 8–9 years of experimental warming, we evaluated changes in SOC quantity and quality of three density fractions of soil: free light fraction (FLF), occluded light fraction (OLF) and heavy fraction (HF). The SOC content at 0–5‐cm depth was significantly reduced with warming under Cassiope, and it was accompanied by decreased FLF content, attributed to accelerated decomposition of the FLF by warming. However, SOC molecular composition and bacterial community composition were not affected by warming. By contrast, there was no warming effect on SOC under Salix, which could be partially due to smaller temperature increases caused by higher moisture levels associated with larger silt and clay contents, or to different responses of the dominant plant species to temperature. In both soils, more than 55% of SOC was associated with minerals, and its molecular composition indicated microbial decomposition. Our results suggested that long‐term warming in the high Arctic could induce the loss of SOC, particularly in the FLF; however, the response could vary with vegetation type and/or soil properties, that is, soil texture.

中文翻译：

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在高寒带苔原的不同荒地类型之间，表面SOC对长期实验变暖的响应有所不同

在过去的几十年中，北极的热度比低纬度地区高。北极地区的土壤有机碳（SOC）易受气候变化的影响，通过SOC分解产生的二氧化碳（CO ₂）可以加剧大气温度的升高。尽管SOC的组成与可分解性有关，但有关变暖的组成变化的研究很少，特别是在北极地区。因此，我们调查了仙后座和柳属植物下SOC和细菌群落对气候操纵的反应格陵兰Zackenberg多年冻土影响土壤中的健康植被群落。经过8–9年的实验变暖，我们评估了土壤三种密度部分的SOC数量和质量的变化：游离轻度部分（FLF），闭塞轻度部分（OLF）和重度部分（HF）。在仙后座条件下，随着温度的升高，0-5 cm深处的SOC含量显着降低，并且伴随着FLF含量的降低，这归因于加热导致FLF的加速分解。然而，SOC分子组成和细菌群落组成不受变暖的影响。相比之下，柳柳对SOC没有变暖作用，这可能部分是由于较高的水分含量（与较大的粉砂和粘土含量相关）或较高的植物对温度的不同响应所引起的温度升高较小。在两种土壤中，超过55％的SOC与矿物质有关，其分子组成表明微生物在分解。我们的结果表明，北极高海拔地区的长期变暖可能导致SOC的损失，特别是FLF。但是，响应可能会随植被类型和/或土壤特性（即土壤质地）而变化。