摘要
以黄土高原刺槐人工林为研究对象,采用手工挖掘法,配合完整土块法获取根系样品,分析幼龄(11a),中龄(22a),成熟(34a)刺槐人工林细根活力、可溶性糖含量、可溶性蛋白含量和细胞膜透性等细根衰老生理指标的差异,为深入了解刺槐细根的生长和衰老机制提供参考。结果表明:(1)在生长季节,刺槐细根活力表现为,幼龄林>成熟林>中龄林,可溶性糖含量、可溶性蛋白含量随着林龄增大而增加,而细胞膜透性则随林龄的增加而减小。(2)随着根序增加,根活力和可溶性糖含量增加,而可溶性蛋白含量和细胞膜透性则呈波动式降低。这表明,在生长季节幼龄林细根较中龄林和成熟林更容易出现衰老,刺槐不同根序衰老具有顺序性,衰老先从1级根开始,然后是2级根和3级根。
Owing to their large surface area and high biological activity, fine roots are the main vegetative organs by which trees absorb water and nutrients, and provide material support for aboveground growth and the physiological metabolism of other underground root systems. The senescence of fine roots affects plant growth and development, stand productivity and the chemical cycle of forest ecosystems. As one of the main tree species for water and soil conservation in the Loess Plateau, Robinia pseudoacacia plays an important role in improving the ecological environment. For this reason, R. pseudoacacia plantations in the Loess Plateau were selected as the study site, and the hand-digging and intact clod methods were used to obtain root system samples to analyze differences in the physiological indicators （e.g., vigor, soluble sugar content, soluble protein content, and cell membrane permeability） of the fine root senescence for plantation stands of different ages[i.e., young forests （11a）, middle-aged forests （22a） and mature forests （34a）]. These results provide a detailed description of the growth and senescence mechanisms of the fine roots of R. pseudoacacia. During the growing season, the vigor of fine roots with respect to forest age, in descending order, was as follows：young forest 〉 mature forest 〉 middle-aged forest. As forest age increased, the soluble sugar content and soluble protein content increased, while the cell membrane permeability decreased. Higher-order roots were associated with increased fine root vigor and soluble sugar content, but nonlinearly decreased soluble protein content and cell membrane permeability. Based on an ANOVA, the fine root vigor, soluble sugar content （except for second-order fine roots）, soluble protein content （except for first-order fine roots）, and cell membrane permeability exhibited significant differences with respect to stand age within root orders （P 〈 0.05）. The differences in fine root vigor （except for middle-aged forests）, soluble protein content （except for young forests）, and cell membrane permeability in roots at identical stand ages exhibited significant differences with respect to root order （P 〈 0.05）. The soluble sugar content differed significantly only in mature forests （P 〈 0.05）. In summary, during the growing season, fine roots of the young forests are more prone to senescence than those of the middle-aged and mature forests. The sequence of fine root senescence in Robinia pseudoacacia begins with first-order fine roots and progresses to second-order and the third-order roots.
出处
《生态学报》
CAS
CSCD
北大核心
2016年第14期4423-4429,共7页
Acta Ecologica Sinica
基金
陕西省自然科学基础研究计划项目(2011JM3001)
西北农林科技大学基本科研创新重点项目(ZD2012012)
国家"十二五"农村领域国家科技计划课题(2012BAD22B0302)
关键词
刺槐
林龄
细根衰老
根序
黄土高原
Robinia pseudoacacia
forest age
fine root senescence
fine root order
the Loess Plateau
