准噶尔盆地荒漠植物的叶片水分吸收策略

Leaf water uptake strategy of desert plants in the Junggar Basin,China

在干旱地区,经常出现只能湿润植物地上部分和表层土壤的小量级降雨和凝结水输入,此量级的水分输入无法通过入渗进入根区土壤而被植物根系吸收利用。最近研究发现,叶片吸收水分是利用小量级降水和凝结水的主要方式。该研究通过鉴定和观测准噶尔盆地东南部5个自然植物群落中夏季地上部分仍存活的所有51种荒漠植物叶片的单位面积吸水量(LWUC)、叶片含水量增加率(Rw)以及其他7种植物功能性状,探讨了这些植物功能性状与植物叶片吸收水分能力的关系。研究结果表明:(1)与Rw相比,LWUC是更加适合评价植物叶片吸收水分能力的指标;(2)植物生活型是相对合理的评价荒漠植物叶片吸收水分能力的植物性状;(3)荒漠植物地上(叶片)和地下(根系)部分吸收水分策略存在着权衡;(4)荒漠植物叶片耗水和吸水存在着权衡。总之,叶片吸收水分策略对于荒漠植物,特别是一年生草本植物最大限度地利用有限的水资源渡过持续的干旱并完成生活史具有重要的意义。

Aims Our objective is to understand leaf water uptake strategy of desert plants and the relationship between leaf water uptake capability and plant ecological functional types in the southeastern Junggar Basin, China. Methods We collected or classified （by the inverse of the normal cumulative distribution function） information from 51 species from five plant communities： growth form, life form, leaf texture trait, leaf surface trait, leaf water uptake content, percentage increase in leaf water content, leaf water deficit, specific leaf area and leaf dry matter content. The correlation coefficient and degree of association were calculated between each pair of traits based on information theory. One-way analysis of variance and Fisher＇s multiple comparison, if applicable, were carried out on means of different soft ecological functional types at the community scale, for comparing leaf water uptake content and the percentage increase in leaf water content. Important findings Leaf water uptake content is more appropriate than percentage increase in leaf water for assessing plant leaf water uptake capability. Plant life form is the most rational soft trait to replace hard plant ecological functional ones in studying plant leaf water uptake strategy. There are tradeoffs between aboveground and belowground water uptake strategies and between leaf water consumption and uptake in the desert ecosystem.