不同土壤质地和淤积深度对大米草生长繁殖的影响

盐沼湿地生态系统中的土壤质地和淤积深度由于受到潮汐和生物的协同作用会发生相应的变化, 将对植物个体生长与湿地植被分布产生影响。本文通过智能温室人工模拟控制土壤质地和淤积深度实验, 分析了不同土壤质地(粘土和混合土)及淤积深度(无淤积、淤积植株高度1/4、淤积植株高度1/2及淤积植株高度3/4)对外来克隆植物大米草(Spartina anglica)种群的生长繁殖特征及生物量积累的影响。结果表明: 粘土促进叶面积、叶片数及根状茎数的增加, 并增加根状茎总长、根状茎生物量及地上生物量的积累; 而混合土(粘土与沙土体积比为1:1)增加了克隆分株数、总生物量、地下生物量及根生物量。除叶面积在淤积株高3/4处理下达到最大值外, 其他指标均在淤积株高1/2处理下达到最大值。由此推断, 大米草种群较适宜的土壤质地及淤积深度为粘土淤积株高的1/2处。据此推测, 可通过相应的生物及工程措施来改良土壤质地及通过改变淤积深度来有效管理我国海岸带大米草的分布, 为控制大米草在海岸带盐沼中的入侵与种群扩张提供了理论依据。

Effects of different sediment type and burial depth on growth traits and biomass accumulation of Spartina anglica

Soils in salt marsh ecosystems have been undergoing certain changes including those related to sediment types and burial depths due to tidal activity and a variety of biotic factors. The changes in sediment type affect water-retaining properties, permeability and organic content while those in burial depth alter soil humidity, nutrition content, oxygen content, light intensity and temperature. Although many previous studies have focused on the effects of soil properties on plant growth and reproduction, few have explicitly tested the impacts of sediment type and burial depth on plants in salt marsh ecosystems. The exotic species Spartina anglica found in coastal China has been experiencing increased mortality over the past decade, however the mechanism of this mortality remains unclear. This study mainly focused on the effects of sediment type and burial depth on growth traits and biomass accumulation of S. anglica and was conducted under greenhouse conditions. The experiment included two types of sediments with clay and clay-sand mixtures (the volume of 1:1). Furthermore, four treatments were established with burial depths from 0 cm to one quarter of the plant height, one half of the plant height and three quarters of the plant height. Results indicated that clay increased leaf area, number of leaves, number of rhizomes, total length of rhizomes, rhizome mass and aboveground mass, while the clay-sand mixture led to an increase in the number of ramets, total mass, underground mass and root mass. All of the measures, except for leaf area, peaked at one half of the plant height burial treatment among all treatments. Overall, burial depth at one half of the plant height in clay was the most suitable combination for S. anglica. The results indicate that changes in sediment properties and subsequent changes in burial depth for S. anglica may assist with management of its populations over the species range.