PARENT SESSION
Contributed Oral Session 124: Grassland Ecology: Water Relations; Growth
Thursday, August 11, 8:00 AM - 11:30 AM, Meeting Room 518 C, Level 5, Palais des congrès de Montréal

Soil water dynamics of model populations of Bouteloua gracilis differing in lignin content.

Arredondo, Tulio^*,1, Huber-Sannwald, Elisabeth¹, Medina, Eduardo¹, ¹ Instituto Potosino de Investigacion Cientifica y Tecnologica, San Luis Potosi, San Luis Potosi, Mexico

ABSTRACT- Most efforts to examine the role of biodiversity on ecosystem functioning have been carried out at both the functional group and the species level. Except for few studies the role of biodiversity on ecosystem processes at the population, the phenotypic and the genotypic levels is still very uncertain. In species poor communities the contribution of the genetic and phenotipic diversity of the key species on ecosystem processes may be comparable to the contribution of species diversity of species rich communities. In this study we examined the role of phenotypic composition of model populations on the dynamics of soil water in the shortgrass steppe in Central Mexico. We selected individuals of Bouteloua gracilis of a group characterized for lignin content and morphology. Individuals were vegetatively propagated and transplanted into 1 sq m plots (9 plants÷plot) combining individuals with low (3 to 3.75 per cent MS) and high (4.5 to 5.5 per cent MS)high ligning content with the following proportions , , all (6 treatments with 7 replicates each). We examined population morphological traits (height, specific leaf area, biomass, etc) and soil volumetric water content (TDR) for each plot. After two growing season the results showed significant differences (P≤0.05) in plant height, leaf area, tiller number, specific leaf area, leaf tissue density among the lignin treatment combinations. Plots including higher proportion of HL individuals exhibited more tillers, shorter statures, less leaf area and lower SLA and higher leaf tissue density than LL plots. No differences were observed for water dynamics, however there were differences (P≤0.05) in the volumetric soil water content. The highest records of soil water content were observed in treatments that included the highest proportion of LL individuals. In the present study it appears that the morphological and chemical characteristics of plots were the factors determining the content of soil water.

Key words: phenotypic diversity, water dynamics, Bouteloua gracilis