Laboratory of Tree-Ring Research, University of Arizona, 105 West Stadium, Tucson, Arizona 85721, USA.
Ecol Appl. 2010 Sep;20(6):1598-614. doi: 10.1890/09-1535.1.
Fire scars are used widely to reconstruct historical fire regime parameters in forests around the world. Because fire scars provide incomplete records of past fire occurrence at discrete points in space, inferences must be made to reconstruct fire frequency and extent across landscapes using spatial networks of fire-scar samples. Assessing the relative accuracy of fire-scar fire history reconstructions has been hampered due to a lack of empirical comparisons with independent fire history data sources. We carried out such a comparison in a 2780-ha ponderosa pine forest on Mica Mountain in southern Arizona (USA) for the time period 1937-2000. Using documentary records of fire perimeter maps and ignition locations, we compared reconstructions of key spatial and temporal fire regime parameters developed from documentary fire maps and independently collected fire-scar data (n = 60 plots). We found that fire-scar data provided spatially representative and complete inventories of all major fire years (> 100 ha) in the study area but failed to detect most small fires. There was a strong linear relationship between the percentage of samples recording fire scars in a given year (i.e., fire-scar synchrony) and total area burned for that year (y = 0.0003x + 0.0087, r2 = 0.96). There was also strong spatial coherence between cumulative fire frequency maps interpolated from fire-scar data and ground-mapped fire perimeters. Widely reported fire frequency summary statistics varied little between fire history data sets: fire-scar natural fire rotations (NFR) differed by < 3 yr from documentary records (29.6 yr); mean fire return intervals (MFI) for large-fire years (i.e., > or = 25% of study area burned) were identical between data sets (25.5 yr); fire-scar MFIs for all fire years differed by 1.2 yr from documentary records. The known seasonal timing of past fires based on documentary records was furthermore reconstructed accurately by observing intra-annual ring position of fire scars and using knowledge of tree-ring growth phenology in the Southwest. Our results demonstrate clearly that representative landscape-scale fire histories can be reconstructed accurately from spatially distributed fire-scar samples.
火疤被广泛用于重建世界各地森林的历史火灾制度参数。因为火疤在空间上离散点提供了过去火灾发生的不完全记录，所以必须通过空间火疤样本网络进行推断，以重建景观火灾频率和范围。由于缺乏与独立火灾历史数据源的经验比较，评估火灾历史重建的相对准确性受到了阻碍。我们在美国亚利桑那州南部米卡山的 2780 公顷黄松林中进行了这样的比较，时间范围为 1937 年至 2000 年。使用火灾周边地图和点火位置的文献记录，我们比较了从文献火灾地图和独立收集的火疤数据（n = 60 个样地）中得出的关键空间和时间火灾制度参数的重建。我们发现，火疤数据提供了研究区域内所有主要火灾年份（> 100 公顷）的空间代表性和完整清单，但未能检测到大多数小火。在给定年份记录火疤的样本比例（即火疤同步性）与该年总燃烧面积之间存在很强的线性关系（y = 0.0003x + 0.0087，r2 = 0.96）。从火疤数据插值得到的累积火灾频率图之间也存在很强的空间一致性。广泛报道的火灾频率汇总统计数据在火灾历史数据集之间变化不大：火疤自然火灾旋转（NFR）与文献记录相差不到 3 年（29.6 年）；大火灾年份（即>或=研究区域 25%燃烧）的平均火灾返回间隔（MFI）在数据集之间相同（25.5 年）；所有火灾年份的火疤 MFI 与文献记录相差 1.2 年。根据文献记录重建过去火灾的已知季节性时间，通过观察火疤的年内年轮位置和利用西南地区树木年轮生长物候学的知识，也得到了准确的重建。我们的结果清楚地表明，可以从空间分布的火疤样本中准确重建具有代表性的景观规模火灾历史。
