Stand-replacing fires reduce susceptibility of lodgepole pine to mountain pine beetle outbreaks in Colorado
Stand-replacing fires reduce susceptibility of lodgepole pine to mountain pine beetle outbreaks in Colorado
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DOI：
10.1111/j.1365-2699.2012.02748.x
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发表时间：
2012-11-01
影响因子：
3.9
通讯作者：
Smith, Jeremy
中科院分区：
文献类型：
--
作者：
Kulakowski, Dominik;Jarvis, Daniel;Smith, Jeremy
由于气候变化正在增加野火和树皮甲虫爆发的频率，严重程度和范围，因此了解这些干扰如何相互作用以影响生态模式和过程，包括对后续干扰的敏感性，这一点非常重要。林分更替火灾和美国西部松大小蠹（Dendroctonus ponderosae）的爆发是落基山脉扭叶松（Pinus contorta）森林的重要干扰。在目前的研究中，我们调查了时间，因为最后的立场取代火灾影响的易感性的立场MPB爆发在这些森林。我们假设，在一个看台规模，年轻的火灾后看台（< c。100150年历史）比旧看台更不容易受到过去和当前MPB爆发的影响。地点美国科罗拉多。方法采用树木生态学方法，重建23个黑松林分的林分起源日期和暴发史。结果大部分林分中最古老的树木的建立日期范围相对狭窄，表明这些林分起源于过去300年的林分替换或部分林分替换火灾之后。林分在1940/1950年代、1980年代和2000/2010年代受到MPB爆发的影响。爆发的易感性一般增加与林龄（即时间，因为最后一个立场取代火灾）。然而，这种较年轻的火灾后看台的易感性降低在20世纪40年代/50年代的爆发中最为明显，在20世纪80年代的爆发中则不那么明显，而在21世纪00年代/21世纪10年代的爆发中则不成立。较年轻的林分可能对最近的爆发不太敏感，因为：（1）在林分达到阈值年龄> 100 - 150年后，林分年龄不影响对爆发的敏感性，或（2）最近爆发的高强度降低了干扰前条件对干扰敏感性的重要性。如果有助于MPB爆发的温暖和干燥的条件同时增加了严重火灾的频率和/或程度，它们可能会因此减轻否则增加的火灾规模对爆发的敏感性。温暖和干燥的气候趋势驱动的严重火灾的潜在增加可能会导致一个负反馈，使黑松林不太容易受到未来MPB爆发。
Aim As climate change is increasing the frequency, severity and extent of wildfire and bark beetle outbreaks, it is important to understand how these disturbances interact to affect ecological patterns and processes, including susceptibility to subsequent disturbances. Stand-replacing fires and outbreaks of mountain pine beetle (MPB), Dendroctonus ponderosae, are both important disturbances in the lodgepole pine, Pinus contorta, forests of the Rocky Mountains. In the current study we investigated how time since the last stand-replacing fire affects the susceptibility of the stand to MPB outbreaks in these forests. We hypothesized that at a stand-scale, young post-fire stands (< c. 100150 years old) are less susceptible to past and current MPB outbreaks than are older stands. Location Colorado, USA. Methods We used dendroecological methods to reconstruct stand-origin dates and the history of outbreaks in 23 lodgepole pine stands. Results The relatively narrow range of establishment dates among the oldest trees in most sampled stands suggested that these stands originated after stand-replacing or partially stand-replacing fires over the past three centuries. Stands were affected by MPB outbreaks in the 1940s/1950s, 1980s and 2000s/2010s. Susceptibility to outbreaks generally increased with stand age (i.e. time since the last stand-replacing fire). However, this reduced susceptibility of younger post-fire stands was most pronounced for the 1940s/1950s outbreak, less so for the 1980s outbreak, and did not hold true for the 2000s/2010s outbreak. Main conclusions Younger stands may not have been less susceptible to the most recent outbreak because: (1) after stands reach a threshold age of > 100150 years, stand age does not affect susceptibility to outbreaks, or (2) the high intensity of the most recent outbreak reduces the importance of pre-disturbance conditions for susceptibility to disturbance. If the warm and dry conditions that contribute to MPB outbreaks concurrently increase the frequency and/or extent of severe fires, they may thereby mitigate the otherwise increased landscape-scale susceptibility to outbreaks. Potential increases in severe fires driven by warm and dry climatic trends may lead to a negative feedback by making lodgepole pine stands less susceptible to future MPB outbreaks.