不同生境对苦竹鞭根形态结构及其异速生长的影响北大核心CSCD

鞭根作为竹子吸收养分和水分的主要器官,其形态结构性状与鞭根对养分斑块的敏感性及养分获取能力紧密相关。该研究选取相邻连续的苦竹(Pleioblastus amarus)纯林和苦竹-杉木(Cunninghamia lanceolata)混交林2种林分类型,将其分为苦竹林中心区、苦竹林界面区、混交林界面区和混交林中心区4种生境,测定4种林区生境的苦竹鞭根形态结构性状指标及生物量,比较其间的连续性变化规律,以明确竹子异质性环境下的生态适应策略。结果表明:(1)不同生境下,纯林界面区的苦竹拥有更高的鞭根节点数、根尖数以及更小的根直径;纯林界面区和混交林界面区的苦竹鞭根比根长、比根面积均显著高于纯林中心区,但两个界面区的苦竹鞭根根直径则表现相反。(2)从苦竹纯林中心区至混交林中心区方向,苦竹鞭根生物量呈逐渐降低的趋势,但苦竹林界面区和混交林界面区间差异不显著。(3)生境对苦竹主要鞭根形态结构性状异速增长速率无明显影响,但显著提高了苦竹林界面区鞭根主要形态结构性状的差异性位移量;不同生境下苦竹鞭根形态结构存在显著差异,苦竹纯林界面区的鞭根形态结构可塑性较强,拥有更高的鞭根活性以及更活跃的生理功能。研究发现,生境对苦竹主要鞭根形态结构性状有显著影响,但对其异速增长速率无明显影响;鞭根直径是苦竹获取资源的重要影响因子,异质生境下苦竹趋向于采取增加鞭根面积和降低鞭根直径的策略以最大化地获取资源。

Effect of Habitats on the Morphological and Structural Characteristic of Rhizome Roots of Pleioblastus amarus and Its Allometric Growth

Rhizome root of bamboos is the major organ for absorbing nutrients and water. Its morphological and structural traits are closely related to the sensitivity of rhizome root to nutrient patches and ability of nutrients absorption. Two stand types of adjacent Pleioblastus amarus forest and mixed forest of P. amarus Cunninghamia lanceolata were selected, and four habitats (central area of P. amarus and Cunninghamia lanceolata forest, boundary zone of P. amarus forest and mixed forest of P. amarus Cunninghamia lanceolata) was established. We determined the morphological, structural traits and biomass of P. amarus rhizome roots in the four habitats, and analyzed the continuous variation among them to reveal the adaptation strategy of P. amarus to heterogeneous habitats. The results showed that: (1) in different habitats, P. amarus in boundary zone of P. amarus forest has a larger number of rhizome root nodes and root tips, and smaller root diameter. The specific root length and specific root area of the two boundary zones were all significantly higher than that of central area of P. amarus forest, while the rhizome root diameter of those two boundary zones changed on an opposite trend. (2) In direction from central area of P. amarus forest to central area of mixed forest, the biomass of rhizome root for P. amarus decreased gradually, but there were no significant differences on biomass of rhizome root between boundary zone of P. amarus forest and boundary zone of mixed forest. (3) The habitats had no significant effects on the allometric growth rate of the main morphological and structural traits of P. amarus, while displacement of the main morphological and structural traits of P. amarus from boundary zone forest increased significantly. There were significant differences on the morphological structure of rhizome root among different habitats. The morphological plasticity of rhizome root of P. amarus from boundary zone forest were higher, and rhizome root vigor and physiological function increased obviously. The results indicated that habitats affected main morphological and structural traits of rhizome root obviously, but only affected their allometric growth rate slightly. Rhizome root diameter played an important role in acquisition of heterogeneous resources. P. amarus tended to increase the area of rhizome root, but decrease its diameter to capture more resources in heterogeneous habitats.