• 论文与研究报告 •

### 失叶率对小黑杨和兴安落叶松幼苗生物量和叶绿素含量的影响

1. 东北林业大学林学院 哈尔滨 150040
• 收稿日期:2013-11-13 修回日期:2014-05-27 发布日期:2015-04-10
• 通讯作者: 严善春
• 基金资助:

### Effects of Defoliations on the Chlorophyll Contents and Biomass of the Poplar (Populus simonii×P. nigra) and Larix gmelinii Seedlings

Li Yuanyuan, Zhang Kai, Li Shuangwen, Yan Shanchun

1. College of Forestry, Northeast Forestry University Harbin 150040
• Received:2013-11-13 Revised:2014-05-27 Published:2015-04-10

【目的】食叶害虫危害可造成树木失叶,影响树木的生物量及碳储量。研究虫害对杨树及落叶松幼苗生物量和叶绿素含量的影响,可为准确评估食叶害虫不同危害程度对杨树和落叶松碳汇能力的影响提供依据。【方法】选取小黑杨及兴安落叶松幼苗,模拟虫害进行剪叶25%,50%和75%处理,以不剪叶植物作为对照。在剪叶处理后第5,10,15,20天和25天取样,分别测定生物量和叶绿素含量的变化。【结果】生物量测定结果表明:各处理对2种幼苗的株高影响不显著(P>0.05),除落叶松失叶50%的根长显著大于对照(P<0.05)外,其他处理幼苗根长无显著变化。各处理的杨树根部鲜、干质量,全株生物量鲜、干质量均显著低于对照,茎鲜、干质量无显著变化。各处理的兴安落叶松根、茎的鲜、干质量及全株生物量鲜、干质量均显著低于对照。叶绿素测定结果表明:杨树叶片中叶绿素a含量高于叶绿素b,各处理组杨树的叶绿素含量均有不同程度的升高。失叶处理后第5天,处理组叶绿素含量比对照组增多,且失叶75%杨树植株叶绿素 a 和a+b 的含量显著高于对照及失叶25%和50%(P<0.05);第10天,失叶率25%,75%处理组叶绿素b和 a+b 含量显著高于对照(P<0.05),各处理之间差异不显著;第15天,叶绿素含量各个处理组之间、及与对照差异均不显著(P>0.05);处理后20天,失叶50%的植株叶绿素a,b和a+b的含量显著低于对照和失叶25%(P<0.05),亦低于75%,但差异不显著;第25天,各处理叶绿素含量与对照间差异不显著(P>0.05),失叶50%显著高于失叶25%(P<0.05),亦高于失叶75%,但差异不显著。落叶松针叶中叶绿含量素b高于叶绿素a。落叶松叶绿素含量,在失叶量25%和75%处理组,有先升高后降低再升高的趋势,第5天叶绿素含量增加(P<0.05),第10天叶绿素含量降低(P<0.05),第15天与对照相比无差异,第20天叶绿素含量明显升高(P<0.05),到第25天叶绿素含量与对照相近;失叶量50%处理组,第5,15,20天叶绿素含量与对照相比明显降低(P<0.05),且第5天和20天亦显著低于另外2组处理;第10天与对照及另外2组差异不显著(P > 0.05),到第25天叶绿素含量明显高于对照和其他2组处理(P<0.05)。【结论】失叶对杨树和兴安落叶松的固碳能力和光合生理反应均有影响,杨树和落叶松通过增加叶绿素含量,提高单位面积的光合能力,在一定程度上补偿其固碳能力的降低和生物量的损失,且杨树的补偿能力强于落叶松。

Abstract:

Defoliations by leaf/needle-feeding insects can cause significant losses of tree growth, biomass, and carbon storage. Potential effects of artificial defoliations at 0%, 25%, 50% and 75% levels to mimic the defoliator damages on biomass and chlorophyll contents of the poplar (Populus simonii×P. nigra) and larch (Larix gmelinii) seedlings at 5, 10, 15, 20 and 25 days after each treatment were investigated in the current study. Our results showed that there were no significant differences among the treatments in the plant height and root length (P > 0.05) for both tree species, except that 50% larch seedling needle removal resulted in a significant increase of root length (P < 0.05). Fresh and dry weights of the poplar seedling roots and whole seedling biomass in the three defoliation treatments were significantly lower than those of the untreated control, whereas the fresh and dry weights of the poplar seedling stems were not different among the treatments and the control. Fresh and dry weights of the larch seedling root, stem and whole seedling biomass in either defoliation group were significantly lower than those in the control group. Defoliations of poplar leaves resulted in different levels of increase in chlorophyll contents ("a" > "b"). Significant increase of chlorophyll contents already occurred at 5th day after the defoliation, with the 75% level being significantly higher than the control and the two lower levels (25% and 50%) for both chlorophyll "a" and "a"+"b" (P<0.05). At 10th day after the defoliation, chlorophyll "a" and "a"+"b" contents of 25% and 75% defoliations were significantly higher than that of the control, and were not different among the treatments. At 15th days after the defoliation, there were no differences in chlorophyll contents among the treatments and the control (P>0.05). At 20th day after the defoliation, chlorophyll "a", "b" and "a"+"b" contents of 50% defoliation were significantly lower than those of 25% defoliation and control; and slightly lower (but not significantly) than those of the 75% level. At 25th day after the defoliation, there were no differences in chlorophyll contents between each treatment and the control (P>0.05). Chlorophyll contents of the 50% defoliation level were significantly higher than those of 25% defoliation treatment, and slightly higher (but not significantly) than those of the 75% level.. In contrast to the poplar leaves, the chlorophyll "b" content was higher than chlorophyll "a" in the larch needles. The chlorophyll contents of larch needles at 25% and 75% defoliation levels showed a pattern of increase-decrease-increase; i.e. increased after the fifth day, decreased after the 10th day, and further decreased to a level similar to the control on the 15th day; its content levels increased again after the 20th day, and reached back to control level at 25th day after the treatments. The larch needle chlorophyll contents in the 50% defoliation group were lower than that of the control at 5th, 15th, and 20th days of the defoliations; the contents at 5th and 20th days were even lower than those in 25% and 75% defoliation groups; the contents at 10th day were not different significantly from the control and 25% and 75% defoliation groups. At 25th day after the 50% defoliation, chlorophyll contents in the larch needles were significantly higher than those of control and 25% and 75% defoliation groups. Our results showed that defoliations have significant impacts on carbon sequestration and photosynthetic physiological responses of both poplar and larch seedlings. Increasing the chlorophyll contents and improving the photosynthesis efficacy (per unit area) should compensate the decreases of carbon sequestration and biomass loss caused by the defoliations to some degrees, and polar seedlings seemed to show a stronger compensation ability than do the larch seedlings.