Legacy effects from one disturbance may influence successional pathways by amplifying or buffering forest regeneration after the next disturbance. We assessed vegetation and tree regeneration in non-serotinous Sierra lodgepole pine (Pinus contorta var. murrayana) stands after a 1984 wildfire which burned with variable severity and again after a high-severity subsequent fire in 2012. The legacy effects of the 1984 fire were amplified; seedlings and saplings were abundant in areas initially burned at low severity (1267 stems ha⁻¹) despite high reburn severity, but regeneration was low in areas twice burned at high severity (31 stems ha⁻¹). Our results suggest that the severity of the 1984 fire may have influenced post-2012 tree regeneration by creating variable fuel loading, which may have affected soils, litter cover and shade after the 2012 fire and therefore affected seedling establishment and survival. A canopy seed bank of unburnt cones from trees killed by the 2012 fire potentially contributed to a strong effect of prior burn severity on regeneration after the 2012 fire despite a lack of serotinous or resprouting tree species, although the influence of this canopy seedbank was likely limited to the year following the fire. Our results suggest that a low- to moderate-severity fire increases forest resilience relative to a high-severity fire even when the next fire burns at high severity.

一种干扰的遗留效应可能会通过放大或缓冲下一种干扰后的森林再生来影响演替路径。我们评估了1984年野火（严重程度各不相同）以及2012年高强度随后的大火之后的非光化塞拉山地松（Pinus contorta var。murrayana）林分的植被和树木的再生。1984年大火的遗留效应是放大 尽管再燃严重程度很高，但在最初以低烈度燃烧的区域（1267茎ha ^-1）中有大量的树苗和树苗，但是在两次以高烈度燃烧的区域（31茎ha ^-1）中的再生率较低。）。我们的结果表明，1984年大火的严重程度可能会通过产生可变的燃料负荷而影响2012年后的树木再生，这可能会影响2012年大火后的土壤，垃圾覆盖和阴影，从而影响幼苗的建立和生存。尽管缺少叶绿素或发芽树种，但2012年大火杀死的树木的未燃烧视锥细胞的树冠种子库可能对先前的燃烧严重程度对再生产生了强烈影响，尽管该树冠种子库的影响可能有限到大火之后的一年。我们的结果表明，即使下一场火灾以高烈度燃烧，低度至中度烈火相对于高度烈火也会提高森林的复原力。