麻竹枝叶生长对钩梢的响应

为了解冠层生物量积累、分配及枝叶大小对麻竹立竹受营林措施干扰(钩梢)后的响应,对不同竹龄全梢、钩梢麻竹地上构件生物量、生物量比、单叶特征、大小枝生物量分配比例及商品竹叶数量进行了调查.结果表明:麻竹立竹地上现存生物量分配格局为秆＞枝＞叶.叶生物量、叶/枝和叶/秆生物量比为2年生＞3年生＞1年生.随着竹龄的增加,枝、秆生物量、地上生物量和枝/秆生物量比总体上呈增加的趋势.2年生和3年生立竹枝、叶生物量分配比例显著高于1年生立竹,秆生物量分配比例显著小于1年生立竹.此外,随着竹龄的增加,立竹减少了对0 ～8 mm枝生物量的分配,增加了对8～16 mm、16 mm以上枝生物量的投入,以提高空间拓展能力,截获更多光资源.钩梢强烈影响了生物量分配格局,显著减小了麻竹立竹枝、叶、秆、地上生物量.钩梢后麻竹立竹增加了枝、叶生物量分配比例,减少了秆生物量的分配比例,同时提高了单叶叶面积和单叶干质量,增加了8～16 mm、16 mm以上枝生物量分配比例,减小0～8 mm枝生物量分配比例,以权衡枝叶的生长,提高立竹对环境的适合度.钩梢后立竹叶/枝、叶/秆、枝/秆生物量比升高,表明生物量分配更多地向叶和枝倾斜.钩梢麻竹商品竹叶数量较全梢麻竹增加29.68％,且发生部位明显降低,钩梢后冠层下部商品竹叶数量增加79.73％,中部商品竹叶数量增加25.81％,降低了采摘高度.在钩梢后的一个生长季内,钩梢影响了麻竹立竹资源利用策略,表现为枝与叶之间关系的变化,但随钩梢年限的增加其变化规律如何尚需进一步研究.

Branch and Leaf Growth of Dendrocalamus latiflorus Response to Truncation

In order to understand the influence of truncation on canopy biomass accumulation, distribution and branch and leaf size of Dendrocalamus latiflorus, the modular biomass, biomass ratio, leaf area and dry weight, the size of branch biomass distribution ratio and the quantity of commodity leaves of D. latiflorus with different ages were measured and analyzed. The results showed that the aboveground modular biomass of D. latiflorus was in the order of stem>branch>leaf. The leaf biomass, leaf/branch biomass ratio and leaf/stem biomass ratio showed a trend of 2a > 3a > 1a. With the increase of age, the aboveground biomass, branch biomass, stem biomass branch/stem biomass ratio of D. latiflorus followed an increasing trend. The allocation proportion of branch biomass and leaf biomass of 2- and 3-year-old D. latiflorus were significantly higher than that of 1-year-old D. latiflorus, while the allocation proportion of stem biomass of 2- and 3-year-old D. latiflorus were significantly lower than that of 1-year-old D. latiflorus. In order to improve the spatial expansion capability to intercept more light resources, the D. latiflorus stand reduced the 0-8 mm branch biomass allocation, while increased the branch biomass input of the 8-16 mm, 16 mm or above. Truncation strongly affected the biomass distribution pattern, significantly reduced the branch, leaf, stem, and aboveground biomass. After truncating, the D. latiflorus stand increased the allocation proportion of branch biomass and leaf biomass, reduced the allocation proportion of stem biomass. At the same time, it improved the single leaf area and dry weight and increased the biomass allocation proportion of 8-16 mm, 16 mm or higher branch, reduced the biomass allocation proportion of 0-8 mm branch for the purpose of balancing the growth of branch and leaf, and improve the environmental suitability of truncated D. latiflorus. After D. latiflorus stand was truncated, the biomass ratio of leaf/branch, leaf/stem, and branch/stem increased, indicating that the biomass allocation inclined to the leaf and branch. Truncation reduced the picking height, the results showed that after D. latiflorus was truncated, the commodity leaf increased by 29.68% compared with the untruncated stand, the number of commodity leaf at the bottom of canopy increased by 79.73% and that in the middle of canopy increased by 25.81%. The change of the relationship between branch and leaf showed that truncation influenced the resource utilization strategy of D. latiflorus stands in the first growing seasons after truncating. However, further studies on change regulation with the age of truncation are needed.