Plant trait to fodder quality relationships at both species and community levels in wet grasslands

Wet grasslands are now widely recognized as providing many ecosystem services. Wet grasslands are still endangered by both conversion to improved grasslands or crops, and abandonment due to the difficulties associated with exploiting such constrained lands. This paper focuses on forage quality, which is one of the most poorly studied provisioning services of wet grasslands. We tested if the relationship between functional traits (Specific Leaf Area (SLA), Leaf Dry Matter Content (LDMC) and Leaf Nitrogen Content (LNC)) and forage quality established for mesophilic grasslands are valid for wet grasslands. This study was conducted both at the species (44 grassland species) and the community scale. Besides evaluation of both the grassland species and the plant community fodder values for cattle feeding, our aim was to look for proxies of fodder quality through plant functional traits. Pepsin cellulase digestibility (dC) and crude protein content (CP), two uncorrelated indices, were chosen to estimate species fodder quality. At the species scale, SLA seems to be the best trait to estimate dC for forbs, sedges and rushes, while LDMC seems more pertinent for grasses. When considering communities, the weighted mean dC, estimated by these two leaf traits according to the species functional group, constitutes an interesting proxy. CP seemed more linked to LNC. This trait allows an estimation of CP at the species scale but is much less relevant at the community scale.