Context

Landscape and local factors govern tree regeneration across heterogeneous post-fire forest environments. But their relative influence is unclear—limiting the degree that managers can consider landscape context when delegating resources to help stand-replacing patches restock successfully.

Objectives

We investigated how landscape and local factors shape tree regeneration across heterogeneous post-fire forest environments. Our research questions were: What is the relative influence of landscape and local factors on tree species presence (RQ1) and stocking density (RQ2) at stand-replacing patches? Do thresholds occur when landscape factors are influential (RQ3)?

Methods

We sampled landscape and local variables at 71 plots near Jackson, Wyoming, United States. We used Random Forests to investigate how local and landscape variables affect post-fire tree recovery. Relative influence was determined using mean decrease in accuracy. Partial dependence plots were used to visualize whether thresholds occurred for variables with mean decrease in accuracy > 15%.

Results

Landscape factors like seed source area were associated with subalpine fir presence and stocking density. But different thresholds occurred. Specifically, subalpine fir presence required 10% seed source area, while stocking density required 40%. Northeast aspects surrounded by > 10% seed source area were most likely to support subalpine fir presence. Conversely, local factors like soil nutrients were associated with lodgepole pine presence, highlighting effects of different regeneration strategies.

Conclusions

Landscape factors bolster spatial resilience and help stand-replacing patches restock naturally. But landscape factors do not support tree regeneration equally across heterogeneous post-fire forest environments. Consequently, considering stand-replacing patches in their landscape context will be critical for future spatial action planning.

中文翻译：

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景观与当地因素之间的相互作用为火灾后森林环境中的空间行动规划提供信息

上下文

景观和当地因素控制着异质火灾后森林环境中的树木再生。但它们的相对影响尚不清楚——限制了管理人员在委派资源以帮助更换支架成功补货时考虑景观背景的程度。

目标

我们研究了景观和当地因素如何在异质的火灾后森林环境中塑造树木再生。我们的研究问题是：景观和当地因素对林分替代斑块的树种存在 (RQ1) 和放养密度 (RQ2) 的相对影响是什么？当景观因素有影响时是否会出现阈值（RQ3）？

方法

我们在美国怀俄明州杰克逊附近的 71 个地块中对景观和局部变量进行了采样。我们使用随机森林来研究局部和景观变量如何影响火灾后的树木恢复。使用准确度的平均下降来确定相对影响。部分依赖图用于可视化是否出现阈值的变量，平均准确度下降 > 15%。

结果

种子源区等景观因素与亚高山冷杉的存在和放养密度有关。但是出现了不同的阈值。具体来说，亚高山冷杉的存在需要 10% 的种子源面积，而放养密度需要 40%。被> 10% 种子源区包围的东北地区最有可能支持亚高山冷杉的存在。相反，土壤养分等局部因素与黑松的存在有关，突出了不同再生策略的影响。

结论

景观因素增强了空间弹性，并有助于自然地更换林分。但是景观因素并不能在异质的火灾后森林环境中平等地支持树木再生。因此，考虑在其景观环境中更换林地斑块对于未来的空间行动规划至关重要。