关键词: 森林火险天气, 拉尼娜, 厄尔尼诺

Abstract: Different parts of twenty dominant plant species in five plantation communities on the subtropical hilly lands in Heshan of Gunagdong as well as the li tters from three of the five plantation communities were sampled, and their gros s caloric value (GCV) and ash content were measured by using a PARR-12 81 oxygen bomb calorimeter and a muffle furnace. Based on the measurements, the ash-free caloric value (AFCV) of the samples was calculated, and the characteri stics of caloric value and ash content of the samples, according to plant part, individual, and plant growth form, were analyzed. The results showed that the GC V and AFCV of leaf, branch, stem wood, stem bark, and root were in the range of 107〖KG-*2〗-〖KG-*7〗2217 kJ·g-1 and 1389〖KG-*2〗-〖KG-*7〗2304 kJ·g-1, respectively. The GCV and AFCV of leaf were significantly higher than those of other parts (P<005), and the individual plant’s weighted m ean values of GCV and AFCV were in the range of 1424〖KG-*2〗-〖KG-*7〗194 3 and 1663〖KG-*2〗-〖KG-*7〗2099 kJ·g-1, respectively. The mean AFCV of plantation communities was in the order of tree layer (1955 kJ·g-1) >shrub layer (1946 kJ·g-1)>herb layer (1877 kJ·g-1), with indigenous coniferous tree (1986 kJ·g-1)>indigenous broad-leaved tre e (1955 kJ·g-1) > exotic eucalyptus (1918 kJ·g-1), while the m ean ash content was just the opposite. In Acacia mangium, coniferous, and  Schima plantation communities, the GCV and AFCV of litters were higher than those of various plant parts (P<001). The litter-falls in A. mangium and coniferous plantations had higher mean GCV and AFCV than the litters and fr esh leaves of tree layer, while the fresh leaves of tree layer in Schima plantat ion showed higher mean GCV and AFCV.

Key words: El Ni?o, forest fire weather, La Ni?a