Aims

Root aerenchyma, a key adaptive trait to anoxic soils has rarely been integrated into trait-based plant ecology. This study aims to evaluate the relationship between root porosity and root economics-related traits among wetland plants, focusing on the effect of aerenchyma on root tissue density, a central trait in plant economics spectrum.

Methods

Root porosity, root tissue density with air-space included (RTD) or excluded (RTDA), and other root traits such as root dry matter content (root dry mass to fresh mass ratio) were measured separately for adventitious and lateral roots of 16 garden-grown Ontario wetland monocots with contrasting root longevities.

Results

Principal component analysis showed that in the root adaptive trait space of wetland plants, the first dimension is defined by economics-related traits, the second dimension by lateral root porosity and the ratio of lateral to adventitious root length, and the third dimension by adventitious root porosity. Interspecific variation in root porosity was unrelated to root economics traits. Consequently, root tissue density excluding air space (RTDA) better differentiated between species with contrasting root longevities than RTD did, consistently both for adventitious and lateral roots. Root dry matter content accurately predicted RTDA.

Conclusions

Interspecific variation in root porosity is independent of root economics: Wetland plants can construct economically conservative or acquisitive roots of any porosity. Consequently, to consistently express root functional relationships among wetland plant species, root tissue density should be expressed with excluding the air space (i.e., RTDA), or with the more easily measured root dry matter content.

中文翻译：

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根系孔隙度对湿地单子叶植物根系性状空间的贡献与经济性状无关

宗旨

根系通气组织是缺氧土壤的关键适应性特征，很少被整合到基于特征的植物生态学中。本研究旨在评估湿地植物根系孔隙率与根系经济相关性状之间的关系，重点关注通气组织对根组织密度的影响，根组织密度是植物经济谱中的一个中心性状。

方法

分别测量了16个花园的不定根和侧根的根孔隙率、含气隙（RTD）或排除气隙（RTDA）以及其他根性状，如根干物质含量（根干质量与鲜质量比） -生长的安大略湿地单子叶植物具有对比的根系寿命。

结果

主成分分析表明，在湿地植物根系适应性性状空间中，第一维由经济相关性状定义，第二维由侧根孔隙度和侧根与不定根长度之比定义，第三维由不定根定义孔隙率。根系孔隙度的种间变异与根系经济性状无关。因此，不包括空气空间 (RTDA) 的根组织密度在具有对比根长的物种之间比 RTD 更好地区分，对于不定根和侧根来说始终如一。根干物质含量准确预测 RTDA。

结论

根系孔隙度的种间变异与根系经济学无关：湿地植物可以构建经济上保守或具有任何孔隙度的根系。因此，为了一致地表达湿地植物物种之间的根功能关系，根组织密度应该不包括空气空间（即 RTDA），或者用更容易测量的根干物质含量来表示。