Explorations into the Physiology and Ecology of Grassland Plants and Ecosystems: One Agronomist’s Academic Journey

Abstract

This review gives an account of one agronomists’ and his teams’ contri- bution to the understanding of some aspects of the physiology and ecology of grassland plants and ecosystems. The topics span across multiple spatial and tem- poral scales, from the cellular basis of leaf growth in grasses, to functional compo- nents of CO2 exchange at leaf to ecosystem scale, the role of carbohydrate (fructan) stores in recycling of sucrose and supporting respiration and vegetative and repro- ductive growth in benign and stressful conditions, the multi-seasonal 18O-ecohydrology of a pasture, last-century climate change effects on intrinsic water-use efficiency and canopy-integrated stomatal conductance of a range of grassland communities with contrasting nutrient status and plant functional group composition, regional scale changes of the C4/C3 abundance ratio in Inner Mongolia grassland, to ecological fingerprints of cattle based agroecosystems derived from the stable isotope composition of animal tissues, such as hair and milk. Much of the research relied on the development or improvement of methodology, including stable isotope techniques, encompassing 13CO2/12CO2 gas exchange and dynamic (or steady-state) labelling systems from leaf-scale in controlled conditions to ecosystem-scale in natural environments, analysis of tracer kinetics with compart- mental models, and interpretations of natural isotope signals in biomass (13C/12C, 15N/14N, 18O/16O) or water pools (18O/16O, 2H/1H) of soil, vegetation, and animals.