Influence of management regime and harvest date on the forage quality of rangelands plants: the importance of dry matter content

Abstract

We investigated the sources of variation in forage quality in plants from species-rich Mediterranean rangelands in southern France. Digestibility was affected by species growth form, harvest date, developmental stage and management regime, and differed between leaves, stems and reproductive parts. The dry matter content of the different plant parts, an estimate of the density of their tissues closely related to fibre content, emerged as a good predictor and an easily measured trait to estimate digestibility in the wide range of species spanned in our study.

Traits determining the digestibility–decomposability relationships in species from Mediterranean rangelands

“…However, leaves often represent a small fraction of the plant, and stems in some species may provide important biomass for herbivores and decomposers. With only a few studies available on interspecific variation in stem digestibility (Bumb et al, 2016) and decomposability (Freschet et al, 2012), we do not know whether the covariation between digestibility and decomposability in stems is comparable with that observed in leaves. We postulate that (1) leaves will present higher digestibility and decomposability than stems, that (2) similar traits will affect the two processes, but (3) the magnitude will be not the same.…”

“…This was done in two steps. First, we obtained in vitro measurements of a reference subsample using a pepsin-cellulase method of Aufrère et al (2007); for more details see Bumb et al (2016). These in vitro measurements come both from previously published values (see Bumb et al, 2016 for details) and from our own samples.…”

“…Studies conducted separately on these two processes provide evidence that leaf digestibility and leaf litter decomposability are generally governed by the same leaf traits (see Garnier et al, 2016 for a synthesis): fibre content, which can be considered as an anti-herbivore defence (Coley, 1988) is negatively correlated to digestibility (Al Haj Khaled et al, 2006;Bumb et al, 2016) and decomposability at the interspecific level (Cobo et al, 2002;Wardle et al, 2002;White et al, 2004;Kazakou et al, 2009). Leaf nitrogen concentration is positively related to both processes (e.g.…”

“…Previous studies demonstrated that differences in management regimes pertaining to defoliation or fertilizer supply affect vegetation structure and function, leading to differences in digestibility (Bumb et al, 2016) and related traits (Pontes et al, 2007;Carrère et al, 2010). So far, digestibility-decomposability relationships have mostly been established for species belonging to different functional types and very few studies have explicitly addressed the effects of the intensity of herbivory and resources availability on these relationships (Wardle et al, 2004).…”

Improving the Yield and Nutritional Quality of Forage Crops

“…Thusly, management schemes for forage crops are very important for yield. For example, choosing when to cut or graze a crop is crucial for subsequent regrowth of the plant ( Karn et al, 2006 ; Asaadi and Yazdi, 2011 ; Bumb et al, 2016 ). To assist in this choice there is scope for the use of molecular markers, with the future possibility of a PCR test for the optimal time harvest based on the expression of candidate genes like storage proteins.…”