Effects of an extended drought period on physiological properties of grassland species in the field

Abstract

A very high percentage (around 70%) of the agronomic area in Switzerland is covered by grasslands at various altitudes where environmental conditions, management, community structure and productivity vary widely. As heat waves and drought are predicted to increase in future climate, survival of plant species in grasslands is a major issue of concern in Central Europe. The effect of summer drought on representative grasslands in Switzerland was studied through drought experiments (using rain-out shelters avoiding natural precipitation) to understand the response of predominant species to changed climatic conditions. The physiological performance (gas exchange, leaf water potential) of selected species was investigated at three locations in Switzerland. The predawn leaf water potential of all species was lower (more negative) under the dryer conditions at the three sites. Net photosynthesis and stomatal conductance of forb and legume species did not show major changes under drought, while grass species showed large decreases at the lowland site. These differences between forb-legume and grass species were not observed at the pre-alpine and alpine site. The apparent drought tolerance of the forb-legume species seems to be due-at least partially-to increased water use efficiency under drought conditions.

Severe water deficit restricts biomass production of Lolium perenne L. and Trifolium repens L. and causes foliar nitrogen but not carbohydrate limitation

“…Connected symbols reflect repeated measurements. DM: dry matter demonstrating generally higher stomatal conductance in T. repens compared to other non-legume species (Bollig and Feller 2014;Signarbieux and Feller 2012). Thus, in combination with our results of carbohydrate reserve accumulation under drought, this indicates that in particular T. repens could maintain a significant C uptake, even under strong water shortage.…”

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

“…The lasting reduction in abundance of T. repens confirm previous observations in which T. repens was reported to be droughtsensitive (e.g. Skinner et al, 2004;Signarbieux and Feller, 2012). However, the drought event did not modify species diversity and evenness, which proves that although a slight change in some species relative abundance occurred, no modification of species assemblage took place.…”

Drought stress and carbon assimilation in a warming climate: Reversible and irreversible impacts

“…Sophisticated equipment with infrared gas analyzer (IRGA) technique allows sensitive measurements of net CO2 assimilation on a leaf area basis, while the analyses of net CO2 assimilation on a per organ or on a per plant basis are more difficult to handle and less often included in research programs (Signarbieux and Feller, 2012). For a comprehensive analyses of plant performance CO2 assimilation in all above-ground plant parts and CO2 release in all below-and above-ground parts throughout the day must be considered as illustrated in Fig.…”