干热河谷草本植物生物量分配及其对环境因子的响应

以干热河谷6种草本植物为对象,研究了水分、养分、刈割对生物量在根、茎、叶的分配及异速生长关系的影响.结果表明:刈割处理叶生物量质量分数从25.1%显著增加到31.2%,茎生物量质量分数从43.7%显著降低到34.2%;养分添加处理根生物量质量分数从34.0%显著降低到30.8%;水分处理对生物量分配没有显著影响.物种对根、茎、叶生物量分配有显著影响,适应贫瘠土壤的物种将更多生物量分配给叶和根,对茎生物量的分配相对较低.物种与环境因子存在显著的互作效应,表明环境因子对不同物种的生物量分配影响不同.适应贫瘠土壤的物种叶-茎标度指数和异速生长常数大于其他物种,而茎-根标度指数和异速生长常数小于其他物种.养分显著增加了叶-茎和叶-根的异速生长常数,刈割显著降低了茎-根的标度指数,水分处理则没有显著效应.环境因素对器官间异速生长关系的影响存在种间差异.生物量分配的种间差异及其对环境因素的响应特征可能对植物适应环境变化产生重要影响.

Biomass allocations and their response to environmental factors for grass species in an arid-hot valley

The effects of water supply frequency, nutrient addition and clipping on biomass allocations among roots, stems and leaves as well as their allometric scaling relationships for six grass species from an arid-hot valley were investigated. The results showed that the fraction of leaf biomass significantly increased from 25.1% to 31.2% and the faction of stem biomass decreased from 43.7% to 34.2% under clipping treatment. Fertilization significantly decreased the faction of root biomass from 34.0% to 30.8%. Water treatments had no significant effect on biomass allocations. Species identity significantly affected biomass allocations among roots, stems and leaves. Species adapted to infertile soils allocated more biomass into leaves and roots and less into stems. There were significant interactions between species and environmental factors, suggesting that the effects of environmental factors on biomass allocations differed among species. Allometric constants and scaling exponents of leaf-stem for species adapted to infertile soils were greater than those for other species. Allometric constants and scaling exponents of stem-root for species adapted to infertile soils were lower than those for other species. In total, nutrient addition significantly increased allometric constants of leaf-stem and leaf-root while clipping significantly reduced scaling exponents of stem-root. The frequency of water supply had no significant effects on the allometric scaling relationships among different organs. The effects of environmental factors on the allometric scaling relationships between different organs differed among species. The differences in biomass allocations and their responses to environmental factors among different species might affect plant adaptations to environmental changes.