Theme 01: Ecophysiology of Grasslands
Description
The aim of this paper is to review knowledge of the ecophysiological mechanisms influencing the dynamics of plant populations in grazed swards. Such an objective requires some definitions. Firstly, it is necessary to define “ecophysiology” as the study of the interactions between biological individuals (plants) with their own environment: how individuals perceive and react to any constraint and change of their environment, and how the functioning of plants as a population can modify their own environment. Such a definition implies a dynamic approach to pant population functioning as resulting from constant plant-plant interactions mediated by micro-environment modifications. In a grazed plant community, these plant to plant interactions are perturbed by spatially explicit defoliation events which have a direct effect on the functioning of defoliated plants and also an indirect effect via the modification of the micro-environment of the neighbour plants. Secondly, it is necessary to define more precisely what we mean by “dynamics of plant population”. Because this paper is restricted to “ecophysiology of grasslands” plant population dynamics are not entirely taken into account in the sense that invasion or recruitment processes of new plants through seed dispersion and seed banks in the soil are not explicitly included in our approach. So the dynamic aspects of plant population discussed in this paper are restricted to competition between individual plants, including ability for clonal reproduction, survival ability, and morphological adaptation to defoliation and neighbourhood interactions. These determine the dynamic evolution of both sward structure for a short term and botanical composition for a longer term in a sward subjected to a given management.
The analysis will focus on three main concepts of ecophysiology: (i) the mechanisms of competition among individual plants within a plant community and their consequences to sward structure dynamics, (ii) the adaptive morphogenetic mechanisms of plants to defoliation and the consequence to plant morphology and sward structure dynamics, and (iii) the interactions between these two types of mechanism for an overall understanding of the vegetation dynamics of a grazed plant community and its consequence for sustainable pasture management.
Included in
Ecophysiology of Grasslands: Dynamic Aspects of Forage Plant Populations in Grazed Swards
The aim of this paper is to review knowledge of the ecophysiological mechanisms influencing the dynamics of plant populations in grazed swards. Such an objective requires some definitions. Firstly, it is necessary to define “ecophysiology” as the study of the interactions between biological individuals (plants) with their own environment: how individuals perceive and react to any constraint and change of their environment, and how the functioning of plants as a population can modify their own environment. Such a definition implies a dynamic approach to pant population functioning as resulting from constant plant-plant interactions mediated by micro-environment modifications. In a grazed plant community, these plant to plant interactions are perturbed by spatially explicit defoliation events which have a direct effect on the functioning of defoliated plants and also an indirect effect via the modification of the micro-environment of the neighbour plants. Secondly, it is necessary to define more precisely what we mean by “dynamics of plant population”. Because this paper is restricted to “ecophysiology of grasslands” plant population dynamics are not entirely taken into account in the sense that invasion or recruitment processes of new plants through seed dispersion and seed banks in the soil are not explicitly included in our approach. So the dynamic aspects of plant population discussed in this paper are restricted to competition between individual plants, including ability for clonal reproduction, survival ability, and morphological adaptation to defoliation and neighbourhood interactions. These determine the dynamic evolution of both sward structure for a short term and botanical composition for a longer term in a sward subjected to a given management.
The analysis will focus on three main concepts of ecophysiology: (i) the mechanisms of competition among individual plants within a plant community and their consequences to sward structure dynamics, (ii) the adaptive morphogenetic mechanisms of plants to defoliation and the consequence to plant morphology and sward structure dynamics, and (iii) the interactions between these two types of mechanism for an overall understanding of the vegetation dynamics of a grazed plant community and its consequence for sustainable pasture management.
