Prediction of specific leaf area distribution in plant communities along a soil resource gradient using trait trade-offs in a pattern-oriented modelling approach

Authored by A Bedecarrats, F Isselin-Nondedeu

Date Published: 2012

DOI: 10.1556/comec.13.2012.1.7

Sponsors: No sponsors listed

Platforms: R

Model Documentation: Other Narrative Mathematical description

Model Code URLs: Model code not found

Abstract

The functional-trait approach to communities focuses on the distribution of traits and on their variations in communities along environmental gradients. We devised a pattern-oriented demarche to predict specific leaf area (SLA) distribution in three plant communities located along an environmental gradient governed by soil fertility and nutrient stress in subalpine gypsic dolines. An individual-based model incorporating physiological mechanisms simulated the growth of thirty functional groups varying in leaf traits (SLA and correlated leaf life-span) and nitrogen (N) stress tolerance which competed with their neighbours for access to light and nitrogen. The SLAs of these groups encompassed the range of SLAs measured in the sites. Leaf traits governed the daily temperature-dependent processes involved in capturing resources (N and light), biomass synthesis and loss, and the value of the parameter Nc governed the decrease in growth rate of organisms according to a decline in N supply. Biomass drove the competitive ability of each plant in its neighbourhood. A soil sub-model described the amount of available nitrogen in the soil. Simulations yielded performances of functional groups according to the availability of nitrogen in the soil. An integration function, which simulated the effects of the dominance process according to the performances of the groups, yielded the frequency distribution of the groups at the community scale. The SLAs patterns were deduced from this distribution. Comparison of simulated and measured distribution of SLA frequency (Kendall tests) showed the model's ability to reproduce realistically SLA distributions along a nutrient gradient; measured SLA community patterns at lower, medium and higher fertility levels matched simulated SLA distribution with respectively 5 to 30, 82, and 154 kg N ha(-1) year(-1). These results demonstrate the efficacy of a strategy based on a pattern-oriented approach and the use of functional traits and trade-offs to predict the distributions of traits and their variations in communities along an environmental gradient.

Tags

Competition Facilitation Strategies Vegetation Consistent Abundance Ecological theory Nitrogen Functional traits Grassland