Forest Sciences Centre of Catalonia, CTFC, Ctra de St. Llorenç de Morunys, km 2, 25280 Solsona, Spain.
Forest Sciences Centre of Catalonia, CTFC, Ctra de St. Llorenç de Morunys, km 2, 25280 Solsona, Spain.
Sci Total Environ. 2018 Jun 15;627:403-416. doi: 10.1016/j.scitotenv.2018.01.227. Epub 2018 Feb 3.
Thinning and prescribed burning are two common operations for reducing fuel accumulation and decreasing the intensity and severity of wildfires. However, the resprouting response of understory species may reduce the effectiveness of fuel load treatments and thus negatively affect the cost-benefit ratio of these treatments. This study focuses on Buxus sempervirens, a slow-growing, multi-stemmed tree species, frequently dominant in the understory of temperate European forests, which resprouts strongly after clearing or burning. The aim was to assess how light availability and burning influence resprouting ability (resprouting or not) and vigor (i.e. the growth of resprouts) after clearing B. sempervirens in thinned stands without slash removal (unburned) or with burning of slash residues (burned), two years after the treatments. All individuals studied resprouted shortly after clearing in unburned stands, whereas almost ca. 40% never resprouted in the burned stands. Fire intensity, measured at the base of 49 individuals, contributed to explaining the likelihood of mortality. The number of resprouts was directly influenced by the pre-treatment size of individuals, but this relationship was lower in burned stands. Fire intensity, recorded in 29 resprouted individuals, also influenced the number of resprouts. Post-treatment light availability, in addition to pre-treatment size, contributed to explaining the volume of the ten largest resprouts and the length of the largest resprout. No tradeoffs between the resprout number and the volume of the ten largest resprouts or the maximum resprout length were found. Our study suggests that burning after clearing reduces the resprouting ability of B. sempervirens. Moreover, avoiding affecting the canopy cover reduces its resprouting vigor and, consequently, increases the effectiveness of understory fuel load treatments.
间伐和计划火烧是减少燃料积累、降低野火强度和严重程度的两种常见作业。然而，林下物种的萌蘖响应可能会降低燃料负荷处理的效果，从而对这些处理的成本效益比产生负面影响。本研究以生长缓慢、多茎的黄杨属常绿树种为对象，该树种常作为欧洲温带森林林下的优势种，在清除或火烧后会强烈萌蘖。本研究旨在评估在未去除（未火烧）或去除（火烧）采伐剩余物的情况下，疏伐林分中清除黄杨后的两年内，光照可用性和火烧对萌蘖能力（萌蘖或不萌蘖）和活力（即萌蘖的生长）的影响。所有研究的个体在未火烧的林分内清除后不久就萌蘖，而在火烧的林分内几乎有 40%的个体从未萌蘖。在 49 个个体的基部测量的火强度有助于解释死亡率的可能性。萌蘖的数量直接受到个体处理前大小的影响，但在火烧林分内这种关系较低。记录在 29 个萌蘖个体中的火强度也影响萌蘖的数量。除了处理前的大小外，处理后的光照可用性还有助于解释十个最大萌蘖的体积和最大萌蘖的长度。未发现萌蘖数量与十个最大萌蘖的体积或最大萌蘖长度之间存在权衡关系。本研究表明，清除后火烧会降低黄杨的萌蘖能力。此外，避免影响林冠覆盖度会降低其萌蘖活力，从而提高林下燃料负荷处理的效果。
