Canopy diversity in relation to carbon fluxes, water use and ecosystem resilience in North American forests.

Scott Ollinger, University of New Hampshire, scott.ollinger@unh.edu (Presenter)
Jingfeng Xiao, University of New Hampshire, j.xiao@unh.edu
Rossella Guerrieri, University of New Hampshire, rossella.guerrieri@unh.edu
Lucie Lepine, University of New Hampshire, lucie.lepine@unh.edu
Heidi Asbjornsen, University of New Hampshire, heidi.asbjornsen@unh.edu

The question of how biological diversity influences the functioning of ecosystems has been of interest for decades and represents one of the grand challenge questions in ecology. In terrestrial ecosystems, most of the work on this topic has come from grasslands and other systems dominated by low stature vegetation that can be experimentally manipulated. Mature forests present a challenge because the size and lifespans of trees make it difficult to conduct manipulative diversity experiments. Although some studies have focused on previously established plantation forests, such opportunities are limited and often don’t coincide with measurements of whole-ecosystem function. The accumulation of data from eddy covariance networks provides a unique opportunity in that the growing temporal coverage over a large number of sites should eventually make it feasible to examine the influence of diversity using statistical, as opposed to experimental, approaches.

Here, we present results from a NASA-supported effort to examine whether forest canopy diversity influences ecosystem fluxes of carbon (C) and water (H2O) and resistance/resilience to environmental change. We combined traditional metrics of species diversity with field measurements of canopy structure and species composition and compared these with measurements of C assimilation and H₂O use at 38 forested sites across the U.S. and Canada. We used regression modeling to examine the influence of diversity while accounting for the effects of potentially confounding factors such as climate, stand age, biomass, forest type, and foliar N concentrations. The resulting models indicated significant diversity effects on C and H₂O fluxes as well as on inter-annual variability in C assimilation. Results are presented with respect to theories of diversity and ecosystem function and we discuss challenges that need to be overcome to further the relevance of flux networks to this important area of ecological theory.

Presentation Type:  Poster

Session:  Theme 1: Tracking habitat change through new integrative approaches and products   (Mon 1:30 PM)

Associated Project(s): 

• Ollinger, Scott: Exploring Relationships among Carbon Cycling, Vegetation Nitrogen Status and Surface Albedo across North American Ecosystems to Improve Land Surface Models ...details
• Ollinger, Scott: Exploring Relationships Among Water Use Efficiency, Canopy Nitrogen and Carbon Cycling across North American Ecosystems to Improve Land Surface Models ...details

Poster Location ID: 101