Data from: Enhanced decomposition and nitrogen mineralisation sustain rapid growth of Eucalyptus regnans after wildfire

Eucalyptus regnans grows rapidly from seed after wildfires, out-competing other species, thereby forming pure stands of mature forests that rank amongst the world's most carbon dense. By global standards, these forests grow on infertile soils. It is unclear how E. regnans is able to obtain large amounts nitrogen (N) from these infertile soils to support its rapid growth after fire. We measured carbon (C) and N stored in plant biomass and photosynthetic rates of E. regnans 2 years after a wildfire and examined whether E. regnans stimulated its own N supply through root-induced increases in microbial decomposition and N mineralization. We compared microbial biomass, gross N mineralization rates and soil C in trenched and rooted plots. Photosynthetic rates of E. regnans seedlings were high and comparable to photosynthetic rates observed in fertilized crops. Presence of roots of E. regnans and allied microflora enhanced gross N mineralization more than fivefold compared to soil without roots present. Soil microbial biomass was more than doubled by root presence. The soil N pulse caused by the fire and N mineralization rates in the absence of roots were too small to account for the large amount of N stored in E. regnans 2 years after the fire. Our results suggest that E. regnans facilitated its rapid growth by enhancing microbial activity and N mineralization. This enhanced microbial activity also contributed to a substantial loss of soil C (˜62% of carbon gained in plant biomass was concurrently lost from soil). Synthesis. At the ecosystem scale, the synergistic effects of plant growth and soil N mineralization need to be carefully assessed against costs to soil C for forests regenerating after disturbance.王桉（Eucalyptus regnans）在野火过后可通过种子快速萌发，通过种间竞争排挤其他物种，最终形成纯林的成熟林分，这类林分属于全球碳密度最高的森林之一。按全球通用的土壤肥力标准，这类林分生长于贫瘠土壤中。目前尚不明确王桉如何从这类贫瘠土壤中获取大量氮（N），以支撑野火过后的快速生长。 本研究在某次野火发生2年后，测定了王桉植株生物量中的碳（C）与氮（N）储量，并测定了其光合速率；同时探究了王桉是否通过根系诱导微生物分解与氮矿化作用增强，主动提升自身的氮供应。我们对比了断根样地与有根系样地中的微生物生物量、总氮矿化速率以及土壤碳含量。 王桉幼苗的光合速率较高，与施肥作物的光合速率相当。与无根系存在的土壤相比，王桉根系及其伴生微生物群落可使总氮矿化速率提升五倍以上；根系的存在可使土壤微生物生物量提升一倍以上。野火引发的土壤氮脉冲效应，以及无根系存在时的氮矿化速率，均不足以解释野火发生2年后王桉体内积累的大量氮储量。 本研究结果表明，王桉通过增强微生物活性与氮矿化速率，促进了自身的快速生长。这种增强的微生物活性同时也造成了土壤碳的大量流失——植株生物量中积累的碳约有62%同时从土壤中流失。 综合分析：在生态系统尺度下，对于受干扰后自然更新的森林，需要结合土壤碳的损失成本，审慎评估植物生长与土壤氮矿化之间的协同效应。