College of Forestry, Hebei Agricultural University, Baoding 071000, Hebei, China.
Hebei Mulan Paddock State Forest, Chengde 068450, Hebei, China.
Ying Yong Sheng Tai Xue Bao. 2023 Aug;34(8):2082-2090. doi: 10.13287/j.1001-9332.202308.006.
We investigated understory fuel loads of natural secondary forests in Hebei Province, China. We analyzed the effects of stand factors, topographic factors, and ground cover factors on the quantity and composition of fuel, established the dynamic models of understory fuel loads, and proposed management measures. The results showed that the understory total fuel load in natural secondary forests was 11.68 t·hm, which exceeded the forest fire potential threshold (10 t·hm). The understory dead fuel load was mainly humus, and the understory living fuel load was mainly shrubs. The 1 h time-lag fuel load increased significantly with increasing canopy density, stand density, stand age, and litter thickness. The 10 h time-lag fuel load increased signi-ficantly with increasing stand density, average tree height, and litter thickness. Humus load decreased significantly with increasing altitude and increased significantly with increasing humus thickness. Herb load increased significantly with increasing sunny slope orientation and herbal coverage. Shrub load increased significantly with increasing slope degree, shrub coverage, and humus thickness. Understory total fuel load decreased significantly with increasing altitude, and increased significantly with increasing stand density, humus thickness, and litter thickness. The results of stepwise regression analysis indicated that stand density, humus thickness, and altitude could better predict the understory total fuel load (=0.775). Therefore, more attention should be paid on the control of stand density of natural secondary forest in Hebei Province. Cleaning of litters and humus on the ground would help prevent forest fires scientifically and effectively.
我们调查了中国河北省天然次生林的林下可燃物负荷。我们分析了林分因子、地形因子和地被物因子对可燃物数量和组成的影响，建立了林下可燃物负荷的动态模型，并提出了管理措施。结果表明，天然次生林林下总可燃物负荷为 11.68 t·hm，超过了森林火灾潜在阈值（10 t·hm）。林下死可燃物负荷主要为腐殖质，林下活可燃物负荷主要为灌木。1 h 时滞可燃物负荷随林冠密度、林分密度、林龄和凋落物厚度的增加而显著增加。10 h 时滞可燃物负荷随林分密度、平均树高和凋落物厚度的增加而显著增加。腐殖质负荷随海拔的升高而显著降低，随腐殖质厚度的增加而显著增加。草本负荷随阳坡方位和草本盖度的增加而显著增加。灌木负荷随坡度、灌木盖度和腐殖质厚度的增加而显著增加。林下总可燃物负荷随海拔的升高而显著降低，随林分密度、腐殖质厚度和凋落物厚度的增加而显著增加。逐步回归分析的结果表明，林分密度、腐殖质厚度和海拔可以更好地预测林下总可燃物负荷（=0.775）。因此，在河北省应更加重视天然次生林的林分密度控制。清理地面上的凋落物和腐殖质有助于科学有效地预防森林火灾。
