Burned area and carbon emissions across northwestern boreal North America from 2001

DOI：

10.5194/bg-20-2785-2023

发表时间：

2023-07

期刊：

Biogeosciences

影响因子：

4.9

通讯作者：

中科院分区：

地球科学2区

文献类型：

作者：

S. Potter;S. Cooperdock;S. Veraverbeke;X. Walker;M. Mack;S. Goetz;J. Baltzer;L. Bourgeau-Chavez;A. Burrell;C. Dieleman;N. French;S. Hantson;E. Hoy;L. Jenkins;J. Johnstone;E. Kane;S. Natali;J. Randerson;M. Turetsky;E. Whitman;E. Wiggins;B. Rogers

抽象的。火灾是阿拉斯加和加拿大北方生态系统的主要干扰因素，并向大气中释放大量碳。随着气候变化，烧毁面积和碳排放量不断增加，这有可能改变碳平衡，使该地区从历史碳汇转变为碳源。因此，跟踪燃烧面积和火灾碳排放随时间的时空变化至关重要。我们在 2001 年至 2019 年间开发了一种新的阿拉斯加和加拿大烧毁区域检测算法，分辨率为 500 m（米），利用更精细的 30 m Landsat 图像来解释不适合燃烧的土地覆盖。该方法严格平衡 500 m 处的遗漏和委托误差，以得出准确的景观和区域规模烧毁面积估计。使用这种新的燃烧面积产品，我们开发了统计模型来预测 NASA 北极-北方脆弱性实验 (ABoVE) 核心和扩展域内同一时期的燃烧深度和碳燃烧。统计模型使用整个领域的现场观测数据库进行约束，并与各种响应变量相关，包括火灾严重程度的遥感指标、火灾天气指数、当地气候、土壤和地形指标。燃烧深度和地上燃烧模型表现最好，地下燃烧模型表现较差。我们估计 2001 年至 2019 年间，ABoVE 区域每年燃烧 2.37×106 公顷（2.37 Mha）（整个阿拉斯加和加拿大为 2.87 Mha），每年排放 79.3 ± 27.96 Tg（±1 标准差）碳 (C)，平均燃烧率为 3.13 ± 1.17 kg C m−2。平均燃烧和燃烧深度显示出该地区西北部严重程度较高到南部和东部严重程度较低的总体梯度。我们还发现，火灾较大的年份和晚季燃烧通常与较高的平均燃烧有关。我们的估计与之前量化北美北部地区燃烧面积、火灾碳排放及其驱动因素的努力基本一致；然而，由于我们使用陆地卫星图像、现场观测的可用性更高以及建模的改进，我们通常估计更高的燃烧面积和碳排放量。这里描述的燃烧面积和燃烧数据集（ABoVE 火灾排放数据库，或 ABoVE-FED）可用于北方火灾科学的局部到大陆规模的应用。

Abstract. Fire is the dominant disturbance agent in Alaskan and Canadian boreal ecosystems and releases large amounts of carbon into the atmosphere. Burned area and carbon emissions have been increasing with climate change, which have the potential to alter the carbon balance and shift the region from a historic sink to a source. It is therefore critically important to track the spatiotemporal changes in burned area and fire carbon emissions over time. Here we developed a new burned-area detection algorithm between 2001–2019 across Alaska and Canada at 500 m (meters) resolution that utilizes finer-scale 30 m Landsat imagery to account for land cover unsuitable for burning. This method strictly balances omission and commission errors at 500 m to derive accurate landscape- and regional-scale burned-area estimates. Using this new burned-area product, we developed statistical models to predict burn depth and carbon combustion for the same period within the NASA Arctic–Boreal Vulnerability Experiment (ABoVE) core and extended domain. Statistical models were constrained using a database of field observations across the domain and were related to a variety of response variables including remotely sensed indicators of fire severity, fire weather indices, local climate, soils, and topographic indicators. The burn depth and aboveground combustion models performed best, with poorer performance for belowground combustion. We estimate 2.37×106 ha (2.37 Mha) burned annually between 2001–2019 over the ABoVE domain (2.87 Mha across all of Alaska and Canada), emitting 79.3 ± 27.96 Tg (±1 standard deviation) of carbon (C) per year, with a mean combustion rate of 3.13 ± 1.17 kg C m−2. Mean combustion and burn depth displayed a general gradient of higher severity in the northwestern portion of the domain to lower severity in the south and east. We also found larger-fire years and later-season burning were generally associated with greater mean combustion. Our estimates are generally consistent with previous efforts to quantify burned area, fire carbon emissions, and their drivers in regions within boreal North America; however, we generally estimate higher burned area and carbon emissions due to our use of Landsat imagery, greater availability of field observations, and improvements in modeling. The burned area and combustion datasets described here (the ABoVE Fire Emissions Database, or ABoVE-FED) can be used for local- to continental-scale applications of boreal fire science.

Burned area and carbon emissions across northwestern boreal North America from 2001–2019

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