Brandeis Thomas J, Woodall Christopher W
USDA Forest Service, Southern Research Station, Knoxville, TN 37919, USA.
Ambio. 2008 Dec;37(7-8):557-62. doi: 10.1579/0044-7447-37.7.557.
Quantification of the downed woody materials that comprise forest fuels has gained importance in Caribbean forest ecosystems due to the increasing incidence and severity of wildfires on island ecosystems. Because large-scale assessments of forest fuels have rarely been conducted for these ecosystems, forest fuels were assessed at 121 US Department of Agriculture forest service inventory plots on Puerto Rico, Vieques, and the US Virgin Islands. Results indicated that fuel loadings averaged 24.05 Mg ha(-1) in 2004-2006. Forest litter decreased from wetter to drier forest life zones. These island forests showed a paucity of coarse woody fuels (CWD) (2.91 Mg ha(-1)) and relatively greater quantities of smaller-sized fine woody fuels (FWD) (10.18 Mg ha(-1) for FWD and 10.82 Mg ha(-1) for duff/litter) when compared to continental tropical forests. Between 2001 and 2006, CWD fuel loads decreased, while fine fuels and litter increased, such that total fuel loads remained constant on a subset of plots on Puerto Rico. This trend indicates that continued decomposition of CWD deposited by the last severe hurricane is balanced by increasing inputs of FWD from recovering and maturing secondary forests. Forest disturbance cycles and successional development must be taken into account by agencies charged with fire protection and risk assessment.
由于加勒比地区岛屿生态系统野火发生频率和严重程度不断增加，对构成森林燃料的倒下木质材料进行量化在该地区森林生态系统中变得愈发重要。由于此前很少对这些生态系统进行大规模的森林燃料评估，因此在波多黎各、别克斯岛和美属维尔京群岛的121个美国农业部森林服务清查地块上对森林燃料进行了评估。结果表明，2004 - 2006年期间燃料负荷平均为24.05 Mg ha(-1)。森林凋落物从较湿润的森林生命地带向较干燥的地带减少。与大陆热带森林相比，这些岛屿森林的粗木质燃料（CWD）较少（2.91 Mg ha(-1)），而较小尺寸的细木质燃料（FWD）数量相对较多（FWD为10.18 Mg ha(-1)，腐殖质/凋落物为10.82 Mg ha(-1)）。在2001年至2006年期间，CWD燃料负荷下降，而细燃料和凋落物增加，因此在波多黎各部分地块上总燃料负荷保持不变。这一趋势表明，上次严重飓风沉积的CWD的持续分解与恢复和成熟的次生林FWD输入增加相平衡。负责防火和风险评估的机构必须考虑森林干扰周期和演替发展。
