In the Intermountain West, land managers masticate pinyon pine (Pinus spp.) and juniper (Juniperus spp.) trees that have encroached sagebrush steppe communities to reduce canopy fuels, alter potential fire behavior, and promote growth of understory grasses, forbs, and shrubs. At three study sites in Utah, 45 sampling plots spanning a range of tree cover from 5% to 50% were masticated. We measured surface fuel load components three times over a 10‐yr period. We also measured tree cover, density, and height as indicators of treatment longevity. Changes in these variables were analyzed across the range of pre‐treatment tree cover using linear mixed effects modeling. We detected decreases in 1‐h down woody debris by 5–6 yr post‐treatment, and from 5–6 to 10 yr post‐treatment, but did not detect changes in 10‐h or 100 + 1000‐h down woody debris. By 10 yr post‐treatment, there was very little duff and tree litter left for all pre‐treatment tree cover values. Herbaceous fuels (all standing live and dead biomass) increased through 10 yr post‐treatment. At 10 yr post‐treatment, pinyon–juniper cover ranged 0–2.6%, and the majority of trees were <1 m in height. Given that 1‐h fuels were the only class of down woody debris that decreased, it may be beneficial to masticate woody fuels to the finest size possible. Decreases in 1‐h down woody debris and duff + litter fuels over time may have important implications for fire behavior and effects, but increases in herbaceous and shrub fuel loads should also be taken into account. At 10 yr post‐treatment, understory grasses and shrubs were not being outcompeted by trees, and average pinyon–juniper canopy cover was <1%. Therefore, tree regeneration was not sufficient to support a crown fire. In areas where sage‐grouse are a management concern, we recommend monitoring tree regeneration at mastication treatments at 10–15 yr post‐treatment.

中文翻译：

---

Pinyon–Juniper咀嚼后的治疗寿命和表面燃料负荷的变化

在西山间，土地管理者咀嚼松柏（Pinus spp。）和杜松（Junipers）spp。）侵害了鼠尾草草原社区的树木，以减少冠层燃料，改变潜在的火灾行为，并促进林下草，草和灌木的生长。在犹他州的三个研究地点，咀嚼了45个采样地，覆盖了从5％到50％的树木覆盖范围。我们在10年的时间内测量了三次表面燃料负荷成分。我们还测量了树木的覆盖率，密度和高度，以此作为治疗寿命的指标。使用线性混合效应模型在预处理树木覆盖范围内分析了这些变量的变化。在处理后的5–6年内，我们检测到1小时下降的木屑减少，在处理后从5–6年到10年，我们检测到下降，但没有检测到10小时或100 + 1000小时的下降的木屑变化。到治疗10年后，对于所有预处理的树木覆盖率值，几乎没有残留物和树木枯枝落叶。经过10年的处理，草本燃料（所有活的和死的生物量）都增加了。处理10年后，松柏覆盖率为0-2.6％，大多数树木的高度小于1 m。鉴于1小时燃料是唯一一种减少的倒木屑，因此最好将木屑咀嚼到尽可能细的尺寸。随着时间的流逝，木质碎片和粉煤灰+垃圾的排放量会减少1小时，这可能对火灾行为和影响产生重要影响，但还应考虑草本和灌木燃料的增加。在处理后的10年内，林下的草和灌木并没有被树木竞争，并且松树-杜松的平均树冠覆盖率不到1％。因此，树木再生不足以支撑树冠大火。在管理鼠尾草的地区，我们建议在咀嚼处理后10–15年监测树木再生。