海防林叶片形态、光合特征和枝条抗性对长期风胁迫的响应

Leaf Morphology, Photosynthetic Characteristics and Branch Resistance Responding to Long-term Wind Stress of Coastal Shelterbelt Species

摘要:

为了解长期风胁迫对海防林的影响，对沿海6种林龄为8~10 a的防护林树种的叶片形态、光合特征及枝条抗性对长期风胁迫的响应特征进行了研究。结果表明，与未受风胁迫海防林相比，长期风胁迫显著降低了女贞（Ligustrum lucidum）、无患子（Sapindus mukorossi）、红楠（Machilus thunbergii）、栾树（Koelreuteria bipinnata）和弗栎（Quercus virginiana）的叶长和叶面积，也降低了女贞和栾树的叶宽和叶片分形指数；长期风胁迫显著降低了6种海防林树种的净光合速率（18%~47%）以及无患子、栾树和弗栎的水分利用效率，而对女贞、红楠和乌桕（Sapium sebiferum）的没有显著影响。此外，受长期风胁迫影响，无患子、红楠和栾树枝条的极限荷载量和弹性模量均显著增加，与枝条直径的正相关性也进一步增强。因此，长期风胁迫会导致海防林树种光合能力下降，但林木个体可通过采取减小叶面积等的适应型策略以及增强枝条抗性等的忍受型策略来应对这种生理性亏缺。在海防林营造和修复的树种选择搭配上，可优先考虑将女贞、红楠和乌桕等栽植在长期受强风胁迫的区域。

Abstract:

In order to understand the effects of wind stress on coastal shelterbelt tree species, leaf morphology, photosynthetic characteristics and branch tensile resistance to long-term wind stress were studied in six coastal shelterbelt tree species, including Ligustrum lucidum, Sapindus mukorossi, Machilus thunbergii, Koelreuteria bipinnata,Sapium sebiferum, and Quercus virginiana with ages of 8-10 years. The results showed that the leaf length and leaf area of L. lucidum, S. mukorossi,M. thunbergii, K. bipinnata and Q. virginiana significantly reduced under long-term wind stress, and also did the leaf width and leaf fractal index of K. bipinnata and L. lucidum. Meanwhile, the net photosynthetic rate of all six tree species had significant inhibition for 18%-47% under long-term wind stress, and the water use efficiency of S. mukorossi, K. bipinnata and Q. virginiana decreased, but that of L. lucidum, M. thunbergii and S. sebiferum had no significant effect. Under long-term wind stress, the maximum branch load and elastic modulus of S. mukorossi, M. thunbergii and K. bipinnata significantly increased, and the positive correlation with branch diameter were further enhanced. Therefore, long-term wind stress reduced the photosynthetic capacities of coastal shelterbelt species, but trees developed adaptive strategies, such as reducing leaf area, and tolerant strategies like enhancing branch resistance to reimburse this physiological deficit. Moreover, concerning the selection and collocation of tree species for the construction and restoration of coastal shelterbelts, priority can be given to L. lucidum, M. thunbergii and S. sebiferum in areas that have been continuously stressed by the strong wind.