西双版纳热带季节雨林和哀牢山中山湿性常绿阔叶林优势植物及地表凋落物层的热值

 测定云南西双版纳热带季节雨林和哀牢山中山湿性常绿阔叶林优势种植物叶片及地表凋落物层的干重热值，分析并比较了两地群落类型热值的差异及其与地理条件的关系。植物叶片分为鲜叶和凋落叶，地表凋落物层分为新鲜凋落物层（L层）和腐叶层（F层）进行取样测量，所有样品在60℃烘干至恒重，样品热值采用Parr1261氧弹式热量计测量。结果表明：西双版纳的11种植物鲜叶和凋落叶干重热值的变化范围分别是14.595 3～19.863 9和14.046 7～19.884 0 kJ·g^－1， L和F层的平均干重热值分别为17.419 6 和14.780 5 kJ·g^－1；哀牢山的10种植物鲜叶和凋落叶干重热值的变化范围分别是17.805 1～21.525 3和17.893 4～21.436 7 kJ·g^－1，L和F层的平均干重热值分别为19.208 4和17.494 7 kJ·g^－1。两地植物鲜叶与凋落叶干重热值的大小顺序近似或一致，即植物鲜 叶干重热值越高，其凋落叶干重热值也越高；植物鲜叶与凋落叶干重热值的差值有正有负， 因物种而异；西双版纳凋落物L与F层之间的热值差值显著地大于哀牢山两层凋落物的热值差值，可能是由西双版纳凋落物的分解速率较快导致的；两地样品的平均干重热值的顺序为：鲜叶＞凋落叶＞L层＞F层；将两地的相应样品对比发现，干重热值呈现为哀牢山＞西双版纳，体现出高海拔＞低海拔、高纬度＞低纬度以及常绿阔叶林＞热带季节雨林的特点。

GROSS CALORIC VALUES OF DOMINANT SPECIES AND LITTER LAYER IN MID-MONTANE MOIST EVERGREEN BROAD-LEAVED FOREST IN AILAO MOUNTATN AND IN TROPICAL SEASON RAIN FOREST IN XISHUANGBANNA, YUNNAN, CHINA

Aims Our objective was to estimate the gross caloric values (GCVs) for two vegetation types and examine the differences. Methods Samples of fresh leaves were collected from 10 dominant species in mid- montane moist evergreen broad-leaved forest in Ailao Mountain and 11 dominant species in tropical seasonal rain forest in Xishuangbanna.Leaf litter samples also were collected and divided into fresh litter layer (L layer) and fermentation layer (F layer). Samples were dried to constant weight at 60℃, and GCV of each sample was measured by a PARR1261 oxygenic bomb calorimeter. Important findings There was a wide range of GCVs in fresh leaves and litter layers in both forests. The GCVs in fresh leaves were higher than in leaf litter for all but six species, with the differences between fresh leaves and leaf litter dependent on species characteristics. In both forests, species with higher GCVs in fresh leaves also had higher GCVs in leaf litter. The difference of GCV between L layer and F layer samples was significantly higher in Xishuangbanna than in Ailao Mountain, suggesting that litter layer decomposes more rapidly in Xishuangbanna. The ranking of mean GCVs from the same stand was fresh leaves > leaf litters > L layer litters > F layer litters. Mean GCVs in Ailao Mountain were consistently higher than those in Xishuangbanna, indicating that GCV was correlated with geographical factors. Forest GCVs are higher at high altitude, high latitude eve rgreen broad-leaved forest than in low altitude, low latitude tropical seasonal rain forest.