Relationship between foliar δ13C and sapwood area indicates different water use patterns across 236 Salix genotypes

Abstract

Key message The relationship between sapwood area and foliar δ 13 C values varies among 236 Salix genotypes, indicating different water use patterns across these genotypes. Abstract The relationship between leaf δ 13 C and plant size (represented by e.g. total leaf area) has been used to analyze different water use patterns of plants. However, the total leaf area (TLA) is difficult to assess in trees. Our aims were to (i) identify a feasible predictor for TLA; (ii) estimate the effects of TLA on leaf-level δ 13 C and δ 18 O values; and (iii) evaluate whether the relationship between leaf-level δ 13 C and a TLA proxy can be used to discriminate between different water use patterns. Various leaf and shoot traits of up to 236 Salix genotypes field-grown in Sweden and Italy were assessed and analyzed. Accumulated shoot diameter and sapwood area (SA) calculated from it were the best predictors for TLA. The SA was significantly correlated with foliar δ 13 C, but not δ 18 O values in some genotypes. The effects of SA on foliar δ 13 C values varied significantly among genotypes, and the foliar δ 13 C-SA relationship could be used to discriminate between different water use patterns across 236 Salix genotypes. Our results demonstrate a great variability of water use patterns across taxonomically closely related plants, and may also have implications for Salix pre-breeding and selection for different drought conditions.

Regional coordination between riparian dependence and atmospheric demand in willows (Salix L.) of western North America

“…The canopies of taller willow species are supported by one or more large trunks, and sapwood area increases exponentially with trunk diameter (Bond‐Lamberty et al., 2002). If all things are equal, an increase in sapwood area results in greater capacity for water supply to meet demand by the transpiring canopy, resulting in greater potential leaf area (Beyer et al., 2018). When willows have access to persistent water, high sapwood area results in high water use and high photosynthetic rates (Beyer et al., 2018), both of which are consistent with high SLA.…”

“…If all things are equal, an increase in sapwood area results in greater capacity for water supply to meet demand by the transpiring canopy, resulting in greater potential leaf area (Beyer et al., 2018). When willows have access to persistent water, high sapwood area results in high water use and high photosynthetic rates (Beyer et al., 2018), both of which are consistent with high SLA. In contrast, shorter willows with smaller sapwood areas and potentially shallower rooting distributions may need to exhibit more water‐use efficient strategies reflected by lower SLA.…”