甘肃南部7种高寒杜鹃生物量分配的异速生长关系

生物量分配模式影响着植物个体生长和繁殖到整个群落的质量和能量流动等所有层次的功能, 揭示高寒灌丛的生物量分配模式不仅可以掌握植物的生活史策略, 而且对理解灌丛碳汇不确定性具有重要意义。该研究以甘肃南部高山-亚高山区的常绿灌丛——杜鹃(Rhododendron spp.)灌丛的7个典型种为对象, 采用全株收获法研究了不同物种个体水平上各器官生物量的分配比例和异速生长关系。结果表明: 7种高寒杜鹃根、茎、叶生物量的分配平均比例为35.57%、45.61%和18.83%, 各器官生物量分配比例的物种差异显著; 7种高寒杜鹃的叶与茎、叶与根、茎与根以及地上生物量与地下生物量之间既有异速生长关系, 也有等速生长关系, 异速生长指数不完全支持生态代谢理论和小个体等速生长理论的参考值; 各器官异速生长关系的物种差异显著。结合最优分配理论和异速生长理论能更好地解释陇南山地7种高寒杜鹃生物量的变异及适应机制。

Allometric relations for biomass partitioning of seven alpine Rhododendron species in south of Gansu

Aims Biomass-partitioning patterns influences the growth and reproduction of individual plant, and the mass and energy flow of a plant community. Revealing the biomass-partitioning patterns of alpine shrubs can help understand their life-cycle strategies and the uncertainty of shrub carbon sink. Methods In this study, the biomass-partitioning ratio and allometric relations of each organ at individual level were analyzed in seven typical evergreen shrub species in Rhododendron in alpine-subalpine of southern Gansu using whole-plant harvesting method. Important findings The results showed that the average fractions of biomass allocation in root, stem and leave for seven Rhododendron species were 35.57%, 45.61% and 18.83%, respectively, with significant differences in fractions of biomass allocation of each among species. There were allometric relations and isometric relations between leaves vs stems, leaves vs roots, stems vs roots, and aboveground biomass vs underground biomass for all species. However, allometric scale did not fully support the reference values of metabolic scaling theory and isometric scaling theory of small plants. There were significant allometric relationships in leaf mass, stem mass and root mass among species. The combination of the optimal partitioning theory and allelotropic theory help better understand the biomass variation and adaptation mechanism of Rhododendron species in mountainous areas in southern Gansu.