Theme 1: Grassland Ecology
Description
Like other populations of biological organisms, the collective aging structure of a population of grass tillers has meaning and consequences far beyond the development of an individual within it. Using various methods, it is possible to assign numerical indices to tiller development so that it can be described numerically. By sampling a population of tillers and assigning a numerical index to each, the average stage of tillers within a population can be calculated and a repeatable assessment of its development determined. The average or mean stage count (MSC) of tiller development is commonly calculated and used to compare the development of grass species, cultivars, and sward responses to any number of variables that can influence development. While meaningful for such purposes, focusing on the average stage overlooks important demographic information about the tiller population that may have significant consequences to its functioning and management. Variation among the maturity of tillers within a grass population has important implications relative to functional attributes of a sward comprised of a tiller population. A more complete analysis of the data should include the number of stages present and an index reflecting the nature of their distribution within the tiller population. By sampling tiller populations over time, it is possible to make useful inferences about the dynamics of their development which has several important implications for crop management and improvement. The objective of this research was to explore the use of diversity indices to describe variation in tiller populations. Two diversity indices, Shannon’s and Simpson, were evaluated using data from a replicated study comparing the growth and development of smooth bromegrass (Bromus inermis Leyss.) and intermediate wheatgrass (Thinopyrum intermedium (Host) Barkworth & D.R. Dewey). Both indices provided repeatable insights into the distribution of growth stages present in the tiller populations that were useful for distinguishing between the two species and among sampling dates.
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Tiller Demography within Synthetic Grass Populations
Like other populations of biological organisms, the collective aging structure of a population of grass tillers has meaning and consequences far beyond the development of an individual within it. Using various methods, it is possible to assign numerical indices to tiller development so that it can be described numerically. By sampling a population of tillers and assigning a numerical index to each, the average stage of tillers within a population can be calculated and a repeatable assessment of its development determined. The average or mean stage count (MSC) of tiller development is commonly calculated and used to compare the development of grass species, cultivars, and sward responses to any number of variables that can influence development. While meaningful for such purposes, focusing on the average stage overlooks important demographic information about the tiller population that may have significant consequences to its functioning and management. Variation among the maturity of tillers within a grass population has important implications relative to functional attributes of a sward comprised of a tiller population. A more complete analysis of the data should include the number of stages present and an index reflecting the nature of their distribution within the tiller population. By sampling tiller populations over time, it is possible to make useful inferences about the dynamics of their development which has several important implications for crop management and improvement. The objective of this research was to explore the use of diversity indices to describe variation in tiller populations. Two diversity indices, Shannon’s and Simpson, were evaluated using data from a replicated study comparing the growth and development of smooth bromegrass (Bromus inermis Leyss.) and intermediate wheatgrass (Thinopyrum intermedium (Host) Barkworth & D.R. Dewey). Both indices provided repeatable insights into the distribution of growth stages present in the tiller populations that were useful for distinguishing between the two species and among sampling dates.
