茂兰喀斯特森林林隙树种更新的动态规律

Studies on the Dynamics of Tree Regeneration in Forest Gaps of the Karst Forest in Maolan National Nature Reserve of Guizhou Province

分析了茂兰喀斯特森林林隙树种不同大小级的数量动态、林隙内幼苗向幼树的转化率以及林隙树种更新类型及特点.结果表明：在小林隙和幼年林隙中,高度小于100 cm或胸径小于1 cm的树木幼苗的密度要明显高于大林隙或成熟林隙,而当林隙面积大于150 m^2或年龄大于20年时,大径级的幼树比例增加.大林隙和成熟林隙中的幼苗向幼树的转化率明显高于小林隙和早期林隙,径级1～5 cm向5～10 cm的转化率最低,5～10 cm径级是树木更新的一个关键阶段.林隙树木更新过程中,个体数量差异主要出现在幼苗（幼树）阶段,当胸径大于10 cm时,个体数量趋于稳定.林隙树木的更新动态主要有5种类型,多数阳性树种的个体密度在更新过程中均有一显著下降过程,属急剧下降型;而多数耐荫树种的个体密度在更新过程中下降不明显,属均匀下降或波动下降型.

The quantitative dynamics of different size classes of trees, the transition rate of seedlings to saplings and the dynamic pattern of tree regeneration in gaps were studied in the karst forest of Maolan National Nature Reserve, Guizhou, China. The results showed that the individual density of seedlings of H〈 100 cm or D〈1 cm was higher in small and young gaps than in large and old gaps, but the density of saplings of large size class was largely in gaps whose size was 〉150 m^2 or age was 〉20 years. The transition rate of seedlings to saplings was higher in large and mature gaps than in small and young gaps. The transition rate of size class of 1-5 cm to 5-10 cm was the lowest and size class of 5-10 cm was the key stage of tree regeneration in gaps. The difference of individual density was mainly in seedling or sapling stage in the course of gap regeneration and the density became stable when diameter of breast of trees was 〉10 cm. There were 5 regeneration patterns of trees in gaps. The individual density of most light-demanding trees declined greatly but the individual density of shade-tolerant trees declined non-distinctively during gap regeneration.