Terrestrial Condition Assessment (TCA) Fire Deficit

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Objective: Identify ecosystems that have a significant proportion of their area burning less frequently than what occurred under historic fire regimes. Often, missed fire cycles were due to human factors, principally fire suppression since early in the 20th Century.
Data: The area of a landscape with a deficient fire frequency was estimated by comparing observed fire frequencies to historical mean fire return intervals. Observed fire frequencies were calculated by determining the frequency of fire for each pixel based on raster data of observed fires from the Monitoring Trends in Burn Severity (MTBS) project. Areas in the unburned to low severity class were removed from this analysis. The ratio of observed to historical fire frequencies (as determined by Landfire MFRI) was used to determine pixels that are burning less frequently than expected. These pixels were then used to determine the percent area of the landscape deficient in fire. For areas with fire return intervals longer than the remote sensing record, the history of effective fire suppression was used to assume not enough fire occurred back to the implementation of widespread suppression starting in the 1920s through 1930s with policies such as the 10 AM rule. Prior to the 1920s, it is assumed fire return intervals were closer to the historic range of variation, although likely reduced due to the constrained role of Indigenous stewardship. Areas highly modified by anthropogenic activities (i.e., those with developed landcovers or agricultural landcovers of pasture and crop cultivation) and areas with a landcover that does not typically burn (i.e., barren or ice) were not included in the calculation. There is a 2 year lag between the most recent MTBS data and the TCA Assessment year (i.e. in the 2024 TCA Assessment, available MTBS data were from 1984-2022). To reduce this lag to 1 year, we compute the Composite Burn Index (CBI) for the year prior to the current assessment year using fire perimeters from National Interagency Fire Center (NIFC) with methods adapted from Parks et al. 2019. The CBI methods were added for the 2022 assessment. Landfire versions used for MFRI and the associated TCA Assessment are: Landfire 2014 (TCA Assessment 2020), Landfire 2016 (TCA Assessments 2021 and 2022) and Landfire 2020 (TCA Assessments 2023 and 2024).
Format: Raster data are ordinal: (1) Deficient (2) Sufficient (3) Excessive.
Resolution: 90m (2023 and 2024 assessments), 30m (2020-2022 assessments).
Source: MTBS fire perimeters, expected fire return interval , CBI methods, National Interagency Fire Center Perimeters (for CBI)
Additional Resources:
Details on Method Changes and Source Data Versions
Overview of the Terrestrial Condition Assessment: TCA Hubsite or Landfire Office Hour Presentation
Explore the results of the most recent assessment: TCA Interactive Data Viewer
Learn more about the TCA KPI: TCA Dashboard
*if you have trouble viewing the Dashboard, please submit a Tableau Viewer Access Request

This record was taken from the USDA Enterprise Data Inventory that feeds into the https://data.gov catalog. Data for this record includes the following resources: ISO-19139 metadata ArcGIS Hub Dataset ArcGIS GeoService For complete information, please visit https://data.gov.

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研究目标：识别区域内拥有显著占比面积、燃烧频率低于历史火灾制度的生态系统。此类未发生的火灾周期通常由人为因素导致，其中以20世纪初以来的火灾防控措施为主因。

数据说明：火灾频率不足的景观面积，通过将观测到的火灾频率与历史平均火灾复燃间隔进行对比估算得出。观测火灾频率的计算方式为：基于火灾严重性监测趋势（Monitoring Trends in Burn Severity, MTBS）项目的观测火灾栅格数据，逐像素统计火灾发生频率。本分析剔除了未燃烧至低严重性等级的区域。观测火灾频率与历史火灾频率的比值（由Landfire MFRI确定）被用于识别燃烧频率低于预期的像素，随后利用这些像素计算火灾频率不足的景观面积占比。
对于火灾复燃间隔长于遥感记录时长的区域，结合有效火灾防控历史进行假设：自1920至1930年代以‘10点规则’等政策全面推行火灾防控以来，该区域实际发生的火灾次数不足。1920年代之前，假设火灾复燃间隔更接近历史变化范围，但由于原住民土地管理的作用受限，实际火灾次数可能有所减少。
受人为活动强烈改造的区域（即建有开发用地或牧场、农作物种植等农业用地的区域），以及通常不会燃烧的土地覆盖类型区域（即裸地或冰川区域）均未纳入本计算。
最新的MTBS数据与陆地状况评估（Terrestrial Condition Assessment, TCA）年份之间存在2年的滞后性，例如在2024年TCA评估中，可用的MTBS数据覆盖时段为1984年至2022年。为将该滞后性缩短至1年，我们采用改编自Parks等人2019年研究的方法，利用美国国家跨部门消防中心（National Interagency Fire Center, NIFC）的火灾边界数据，计算当前评估年份前一年的综合燃烧指数（Composite Burn Index, CBI）。CBI计算方法自2022年评估起新增启用。
用于MFRI及对应TCA评估的Landfire版本如下：Landfire 2014（对应2020年TCA评估）、Landfire 2016（对应2021、2022年TCA评估）以及Landfire 2020（对应2023、2024年TCA评估）。

数据格式：栅格数据为序数型，分为三类：(1) 火灾频率不足 (2) 火灾频率充足 (3) 火灾频率过高

空间分辨率：2023、2024年评估为90米，2020至2022年评估为30米

数据来源：MTBS火灾边界数据、预期火灾复燃间隔、CBI计算方法、美国国家跨部门消防中心火灾边界数据（用于CBI计算）

附加资源：
- 方法变更与源数据版本详情
- 陆地状况评估概述：TCA中心站点或Landfire办公时段演示文稿
- 查看最新评估结果：TCA交互式数据查看器
- 了解更多TCA关键绩效指标信息：TCA仪表盘
*若无法正常查看仪表盘，请提交Tableau查看器访问申请

本数据集记录源自美国农业部企业数据清单（USDA Enterprise Data Inventory），该清单纳入了https://data.gov目录。本记录包含的资源如下：ISO-19139元数据、ArcGIS Hub数据集、ArcGIS地理服务。如需获取完整信息，请访问https://data.gov。