河西走廊荒漠绿洲过渡带3种典型一年生藜科植物构件生长及生物量分配特征

Module growth and biomass allocation of three typical Chenopodiaceae annuals in a typical desert-oasis ecotone of the Hexi Corridor in Gansu Province,China

藜科一年生草本植物白茎盐生草、刺沙蓬和雾冰藜是荒漠绿洲过渡带人工防风固沙林草本层的优势植物,在维持过渡带生态功能稳定方面发挥着不可替代的作用。以河西走廊荒漠绿洲过渡带的上述3种藜科植物为研究对象,通过野外大面积取样,对其地上、地下各构件数量性状和生物量进行系统分析,研究3种植物在营养生长期不同阶段的构件生长和生物量分配特征,揭示3种植物在不同生长阶段的生长策略,为深入认识其生态适应机理和荒漠生态系统的保育提供参考。结果表明:1)营养生长期间,3种植物的构件生长和生物量积累变异程度不同,地上和地下生物量表现为强变异,且变异系数相近,地上构件中变异程度最强的为叶片,而地下构件中变异程度最强的为侧根;2)3种植物的构件生长和生物量积累在营养生长期不同阶段差异显著(P<0.05),主根生长主要发生在前期和中期,而茎干、叶片、分枝和侧根生长主要在中期和后期;3)3种植物地上构件数量性状(茎高、分枝数和叶片数)和地上生物量在营养生长期内主要表现为异速生长关系,而地下构件数量性状(主根长和侧根数)与地下生物量在营养生长期前期表现为异速生长关系,中期和后期关系不显著;4)3种植物的根冠比(R/S)随营养生长期的推进逐渐降低,地上生物量分配比例不小于86%,地下生物量分配比例不超过14%,且个体较大的植株R/S较小。

Halogeton arachnoideus,Salsola ruthenica and Bassia dasyphylla are the dominant plants in the herb layer of artificial wind-breaking and sand-fixing vegetation in the desert-oasis ecotone,and they play an important role in maintaining the stability of the ecolosystem function in the transition zone. We studied the above three Chenopodiaceae annuals in the desert-oasis ecotone of Hexi Corridor,and through extensive sampling in the field,the characteristics of module growth and biomass allocation of the three species at different stages of the vegetative growth period were examined. The quantitative characters and biomass allocation of both above-ground and belowground modules were analyzed,to reveal the growth strategies of the three species at different growth stages and provide reference for further understanding of their ecological adaptation mechanisms and development of conservation initiatives for the desert ecosystem. It was found that:1)During the vegetative growth period,the three species differed in the patterns of variation in component growth and biomass accumulation. Above-ground and below-ground biomass showed strong variation with similar coefficients of variation,and leaves and lateral roots had the greatest variability in formation of above-ground and below-ground modules. 2)The module growth and biomass accumulation of the three species differed significantly at different stages of the vegetative growth period(P<0. 05).The growth of primary roots mainly occurred in early and mid-vegetative growth,while the growth of stems,leaves,branches and lateral roots mainly occurred in mid-and late-vegetative growth. 3)The quantitative traits of aboveground modules(stem height,branch number and leaf number)and the above-ground biomass of the three species showed an allometric relationship during the vegetative growth period,while the quantitative traits of below-ground modules(main root length and lateral root number) showed the allometric relationship in early growth,and the relationship was not significant in mid-and late-vegetative growth. 4)The root∶shoot mass ratio(R∶S)of the three species decreased gradually as the vegetative growth period progressed. The above-ground biomass distribution ratio was more than 86%,and the below-ground biomass distribution ratio was less than 14%,and larger plants have lower R∶S.