Context

Spatial patterns of high-severity wildfire in forests affect vegetation recovery pathways, watershed dynamics, and wildlife habitat across landscapes. Yet, less is known about contemporary trends in landscape patterns of high-severity burn patches or how differing federal fire management strategies have influenced such patterns.

Objectives

We assessed fires managed for ecological/resource benefit and fires that are fully suppressed and investigated: (1) whether spatial patterns of high-severity patches differed by management strategy, (2) whether spatial patterns were related to fire size and percent high-severity fire, and (3) temporal trends in spatial patterns.

Methods

We examined high-severity spatial patterns within large fires using satellite-derived burn severity data from 735 fires that burned from 1984 to 2017 in Arizona and New Mexico, USA. We calculated a suite of spatial pattern metrics for each individual fire and developed a method to identify those which best explained variation among fires.

Results

Compared to managed fires, spatial pattern metrics in suppression fires showed greater patch homogeneity. All spatial pattern metrics showed significant relationships with fire size and percent high-severity fire for both management strategies. Mean annual spatiotemporal trends in suppression fires have moved toward smaller, more complex, fragmented patches since the early 2000s.

Conclusions

Increases in fire size and proportion high-severity fire are driving more homogenous patches regardless of management type, with percent high-severity more strongly driving average temporal trends. Anticipated shifts in fire size and severity will likely result in larger, more contiguous, and simple-shaped patches of high-severity fire within southwestern conifer forests.

中文翻译：

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管理策略影响美国西南部高严重烧伤斑块的景观模式

语境

森林中高强度野火的空间模式影响植被恢复途径、流域动态和跨景观的野生动物栖息地。然而，人们对高严重度烧伤斑块景观模式的当代趋势或不同的联邦火灾管理策略如何影响这些模式知之甚少。

目标

我们评估了为生态/资源利益而管理的火灾和完全抑制的火灾，并调查了：（1）高严重性斑块的空间模式是否因管理策略而异，（2）空间模式是否与火灾规模和高严重性百分比有关火，以及（3）空间格局的时间趋势。

方法

我们使用来自 1984 年至 2017 年在美国亚利桑那州和新墨西哥州发生的 735 场火灾的卫星得出的燃烧严重程度数据，研究了大火中的高严重程度空间模式。我们为每个单独的火灾计算了一套空间模式指标，并开发了一种方法来识别那些最能解释火灾之间变化的方法。

结果

与受控火灾相比，灭火中的空间模式指标显示出更大的斑块均匀性。对于两种管理策略，所有空间模式指标都显示出与火灾规模和高危火灾百分比的显着关系。自 2000 年代初以来，扑灭火灾的年均时空趋势已朝着更小、更复杂、更碎片化的区域发展。

结论

无论管理类型如何，火灾规模和高严重性火灾比例的增加都推动了更同质的补丁，高严重性百分比更强烈地推动了平均时间趋势。火灾规模和严重程度的预期变化可能会导致西南针叶林内出现更大、更连续、形状简单的高强度火灾斑块。