Measurement of fine root tissue density: a comparison of three methods reveals the potential of root dry matter content

Aims

Root tissue density (RTD, the ratio of root dry mass to root volume) is a fundamental trait in comparative root ecology, being increasingly used as an indicator of plant species’ resource use strategy. However, the lack of standardized method to measure this trait makes comparisons tricky. This study aims to compare three methods commonly used for determining fine RTD and to test whether root dry matter content (RDMC, the ratio between root dry mass and root fresh mass) could be used as a surrogate of fine root tissue density.

Methods

RTD of 163 fine root samples was determined using (i) Archimedes’ method, (ii) image analysis (WinRHIZO software), and (iii) using the root dry matter content as a proxy. Root samples belonged to different herbaceous species grown in different conditions.

Results

RTD measured with Archimedes’ method was positively correlated with RTD estimated with image analysis and with RDMC. However we demonstrated that RTD measured with Archimedes’ method was better predicted by RDMC (R²?=?0.90) than by RTD measured with image analysis (R²?=?0.56). The performance and limitations of each method were discussed.

Conclusion

RDMC is a quick, cheap and relatively easy measurable root attribute; we thus recommended its measurement as a proxy of fine root tissue density.     

Decomposition rates of fine roots from three herbaceous perennial species: combined effect of root mixture composition and living plant community

Plant and Soil - In most ecosystems, plant roots from different species decompose in mixtures and in the presence of living roots; however much root decomposition research has focused on how roots...