Relations between root anatomical traits and leaf resource-use efficiency in alpine meadows of the Tibetan Plateau

Water and nutrient availability in soil can affect leaf resource-use efficiency. Within a given location and given common soil conditions, variations in root anatomical traits across co-existing species determine nutrient and water supply to leaves. Therefore, leaf resource-use efficiency may be closely related to their root anatomical traits. However, few studies have specifically investigated whether and how root anatomical traits affect leaf resource-use efficiency.

Here, we sampled the first two order roots and leaves of 61 herbaceous species in alpine meadows of the Tibetan Plateau. A series of root anatomical traits, leaf photosynthetic nitrogen-use efficiency (PNUE), photosynthetic phosphorus use-efficiency (PPUE) and instantaneous water-use efficiency (iWUE) were examined.

We observed that root anatomical traits, PNUE and PPUE differed distinctively among plant functional groups, while no significant differences in iWUE were detected. Principal component analysis (PCA) revealed a two-dimensional trait space: i.e., stele-related dimension and cortex-related dimension. PNUE and PPUE were tightly correlated with cortical traits, and iWUE was closely correlated with stelar traits. Unexpectedly, we found an independent change between PNUE/PPUE and iWUE.

These results indicate close relations between leaf nutrient-use efficiency and root cortical traits, as well as between leaf water-use efficiency and stelar traits. Therefore, these findings provide important information to link leaf resource-use efficiency to root anatomical traits.