Using high spatial resolution satellite imagery to map forest burn severity across spatial scales in a Pine Barrens ecosystem

Abstract

As a primary disturbance agent, fire significantly influences local processes and services of forest ecosystems. Although a variety of remote sensing based approaches have been developed and applied to Landsat mission imagery to infer burn severity at 30m spatial resolution, forest burn severity have still been seldom assessed at fine spatial scales (≤5m) from very-high-resolution (VHR) data. We assessed a 432ha forest fire that occurred in April 2012 on Long Island, New York, within the Pine Barrens region, a unique but imperiled fire-dependent ecosystem in the northeastern United States. The mapping of forest burn severity was explored here at fine spatial scales, for the first time using remotely sensed spectral indices and a set of Multiple Endmember Spectral Mixture Analysis (MESMA) fraction images from bi-temporal — pre- and post-fire event — WorldView-2 (WV-2) imagery at 2m spatial resolution. We first evaluated our approach using 1m by 1m validation points at the sub-crown scale per severity class (i.e. unburned, low, moderate, and high severity) from the post-fire 0.10m color aerial ortho-photos; then, we validated the burn severity mapping of geo-referenced dominant tree crowns (crown scale) and 15m by 15m fixed-area plots (inter-crown scale) with the post-fire 0.10m aerial ortho-photos and measured crown information of twenty forest inventory plots. Our approach can accurately assess forest burn severity at the sub-crown (overall accuracy is 84% with a Kappa value of 0.77), crown (overall accuracy is 82% with a Kappa value of 0.76), and inter-crown scales (89% of the variation in estimated burn severity ratings (i.e. Geo-Composite Burn Index (CBI)). This work highlights that forest burn severity mapping from VHR data can capture heterogeneous fire patterns at fine spatial scales over the large spatial extents. This is important since most ecological processes associated with fire effects vary at the <30m scale and VHR approaches could significantly advance our ability to characterize fire effects on forest ecosystems.

Plant phenotyping relevance

高解像度衛星画像とスペクトル解析により森林の火災被害（burn severity）を樹冠・区画スケールで推定し、航空写真等で精度検証しており、植物状態の取得手法が研究の中心である。

Code and data availability

植物フェノタイピング解析を再現する公開資産であることを、入力本文と直接リンクから確認できなかったため保留しました。

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