荒漠草原土壤相对湿度对猪毛蒿表型可塑性的影响

猪毛蒿(Artemisia scoparia)为菊科蒿属草本植物,是一种适应性较强的广幅种。研究荒漠草原不同土壤相对湿度条件下猪毛蒿的表型可塑性,对认识异质生境下猪毛蒿的生存适应策略具有重要的生态学意义。结果表明:株高、茎粗、根长、根重和单株生物量均表现出随土壤相对湿度的增大而增加的趋势,对异质生境具有较强的可塑性,而根冠比则表现出相对的稳定性。植株不同部位生物量大小排序为:上部中部下部,且植株下部显著大于上部生物量(P0.05)。土壤相对湿度40%生境下的头状花序数量和重量显著高于土壤相对湿度30%和30%—40%生境。繁殖器官绝对投入量(lg R)随着个体大小(lg V)的增大呈极显著的增加(P0.001),繁殖阈值介于1.868—2.006 g。随着土壤相对湿度的增加,繁殖分配比例极显著增大(P0.001)。营养器官和繁殖器官生物量、头状花序重量和数量、地下生物量和地上生物量均呈极显著线性正相关关系(P0.001),存在正向权衡。单个头状花序重量并不随个体大小和头状花序数量的增加而发生显著变化(P0.05),且在不同土壤相对湿度和不同部位间均无显著差异(P0.05)。由此可见,猪毛蒿在异质生境下产生的可塑性是其生存繁殖的重要反应机制之一。

Effects of heterogeneous habitats on phenotypic plasticity of Artemisia scoparia in the desert steppe of China

Artemisia scoparia is a herbaceous plant of the composite family and a widely distributed species with a high degree of adaptability. The phenotypic plasticity of A. scoparia in different levels of relative soil humidity was addressed in this paper, which has important ecological significance for revealing survival adaptation strategies of A. scoparia in heterogeneous habitats. The results showed that plant height, stem diameter, root length, root weight, and biomass all showed an increasing trend with an increase in soil relative humidity; these factors exhibited strong plasticity across the soil water heterogeneous habitat, whereas the root/shoot ratio showed no change. The order of the biomass of different parts was:upper part < middle part < lower part, and the lower part was significantly heavier than the upper part (P < 0.05). The number and weight of the head inflorescence in the high soil relative humidity (> 40%) habitat were significantly greater than that in the lower soil relative humidity (< 30% and 30%-40%) habitats. The absolute input of reproductive organs (lg R) increased with the increase of individual size (lg V) and showed a significant positive correlation (P < 0.001). The reproductive threshold was between 1.868-2.006 g. With the increase of soil relative humidity, the proportion of reproductive allocation was significantly increased (P < 0.001). There were significant positive linear correlations between vegetative organs and reproductive organs, weight, number of the head inflorescences, and underground and aboveground biomass (P < 0.001). This indicated that there were positive trade-offs between each pair. However, the weight of a single head inflorescence did not change significantly with the increase of individual size or the number of head inflorescences (P > 0.05), and there were no significant differences in the different soil relative humidity habitats and for the different parts of the plant (P > 0.05). The phenotypic plasticity of A. scoparia in the heterogeneous environment of soil water is one of the important mechanisms for its survival and reproduction.