Plant trait–digestibility relationships across management and climate gradients in permanent grasslands

Abstract

International audience1. Dry matter digestibility is a critical component of herbage nutritive value, a major service delivered by grasslands. The aim of this study was to test whether the dominance hypothesis applies to assess the impacts of environmental gradients and management regimes on thiscomponent of herbage nutritive value in permanent grasslands. 2. At the plant level, digestibility has been related to a number of functional traits, but whether this can be scaled up to the community level in species-rich grasslands and how such relationships are modulated by environmental conditions and management regimes remainunknown. Our primary objective was to test whether community-weighted means – species trait values weighted by the species abundance – of morphological, phenological and chemical traits could be used to explain variations in digestibility over a large range of climatic contexts,soil resource levels and management regimes. Our second objective was to explain variations in community digestibility within and among nine contrasting sites along large natural and man-induced environmental gradients.3. Over the whole data set, digestibility and most community-weighted means of traits responded to climatic factors and management regimes, but relations were not always significant when each site was considered separately. Community digestibility was significantly related to one or more plant traits within each site and to all of the measured traits when considering all the sites. Leaf dry matter content (LDMC) had the most consistent effects on digestibility, with a strikingly similar negative effect within each site. Potential evapotranspiration was negatively related to digestibility and contributed to explain a large part of the among-site variance. In addition, a low return interval of disturbance and a high disturbance intensity (biomass removal) were both associated with a high digestibility.4. Synthesis and applications. Disturbance regime, plant traits and local climate impacted dry matter digestibility roughly equally in grasslands. The effects of community composition on digestibility and its response to abiotic factors could be successfully captured by community weightedmeans of leaf dry matter content. This functional marker can be used to develop indicators and grassland management rules to support farmers in the refinement of their practices towards specific needs, such as target production outputs

How to implement biodiversity-based agriculture to enhance ecosystem services: a review

“…lack generality) and (ii) are usually not useful for developing or managing diversified agroecosystems. For example, knowledge about grassland ecosystem services has greatly increased through the use of the "trait" approach (e.g., Gardarin et al 2014); however, stakeholders cannot use it for their own situations because it is too time consuming and requires specific skills. New research projects have been launched to bridge this gap through a simplified plant functional-group method .…”

Assessing the Effects of Grassland Management on Forage Production and Environmental Quality to Identify Paths to Ecological Intensification in Mountain Grasslands

“…Forage digestibility (2) and total nitrogen content (3) were measured on four 50 cm 9 50 cm vegetation samples per plot. Samples were mixed, dried for 72 h at 60°C, ground with a 0.5 mm grid, and then analyzed using Near InfraRed Spectrometry (Gardarin et al 2014). The other five agronomic properties were derived from the relative abundance of grass species.…”

“…This result suggests that management can partially decouple forage production from forage quality despite the higher potential of the most productive grasslands for forage associated with a short leaf lifespan index. This relative potential for decoupling production and quality may reflect a major influence of grass functional composition rather than a direct effect of management (Duru et al 2008;Gardarin et al 2014). Although Lavorel et al (2011) showed that forage quality decreased with extensification of management in mountain grasslands, we found no significant differences in forage quality between the different grassland types within hay meadows or pastures.…”

Drought-induced shifts in plants traits, yields and nutritive value under realistic grazing and mowing managements in a mountain grassland

“…seasonal) duration (Jung et al, 2014;Lloret et al, 2012;Suding et al, 2008). Such changes in community plant traits can ultimately influence agronomic services such as forage yields and its nutritive value (Gardarin et al, 2014;Quétier et al, 2007).…”