Department of Ecology and Environmental Sciences, Umeå University, SE-901 87 Umeå, Sweden; Ecology & Biodiversity Group, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands; Plant Ecophysiology Group, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands.
Department of Earth Sciences, University of Gothenburg, PO Box 460, SE-405 30 Gothenburg, Sweden.
Sci Total Environ. 2020 Jul 1;724:138304. doi: 10.1016/j.scitotenv.2020.138304. Epub 2020 Mar 30.
Litter decomposition is an important driver of soil carbon and nutrient cycling in nutrient-limited Arctic ecosystems. However, climate change is expected to induce changes that directly or indirectly affect decomposition. We examined the direct effects of long-term warming relative to differences in soil abiotic properties associated with vegetation type on litter decomposition across six subarctic vegetation types.
In six vegetation types, rooibos and green tea bags were buried for 70-75 days at 8 cm depth inside warmed (by open-top chambers) and control plots that had been in place for 20-25 years. Standardized initial decomposition rate and stabilization of the labile material fraction of tea (into less decomposable material) were calculated from tea mass losses. Soil moisture and temperature were measured bi-weekly during summer and plant-available nutrients were measured with resin probes.
Initial decomposition rate was decreased by the warming treatment. Stabilization was less affected by warming and determined by vegetation type and soil moisture. Soil metal concentrations impeded both initial decomposition rate and stabilization.
While a warmer Arctic climate will likely have direct effects on initial litter decomposition rates in tundra, stabilization of organic matter was more affected by vegetation type and soil parameters and less prone to be affected by direct effects of warming.
在养分有限的北极生态系统中，凋落物分解是土壤碳和养分循环的重要驱动因素。然而，气候变化预计会直接或间接地引起分解的变化。我们研究了长期变暖相对于与植被类型相关的土壤非生物特性差异对六种亚北极植被类型凋落物分解的直接影响。
在六种植被类型中，将 rooibos 和绿茶袋埋在 8 厘米深的地方，在已放置 20-25 年的加温（通过开顶室）和对照小区中。从茶的质量损失中计算出标准化初始分解率和茶中易分解物质部分（转化为较难分解的物质）的稳定化。在夏季每两周测量一次土壤水分和温度，并使用树脂探针测量植物有效养分。
初始分解率受加温处理的影响而降低。稳定化受变暖影响较小，由植被类型和土壤水分决定。土壤金属浓度阻碍了初始分解率和稳定化。
虽然北极气候变暖可能会对苔原的初始凋落物分解率产生直接影响，但有机质的稳定化受植被类型和土壤参数的影响更大，不太容易受到变暖的直接影响。
