PARENT SESSION
Poster Session #71: Plant Ecology: Physiology and Function.
Friday, August 9. Presentation from 8:00 AM to 9:30 AM. Exhibit Hall B & C, TCC

Assessing the key features driving large scale patterns of gross primary production across forest ecosystems: A comparison across Europe and North America.

Economo, Evan^*,1, Ignace, Danielle¹, Huxman, Travis¹, Enquist, Brian¹, ¹ University of Arizona, Tucson, AZ

ABSTRACT- Establishing empirical patterns of energy flow through ecosystems is a central focus in the evaluation of current theories of ecosystem level ecology, and ultimately, global patterns of biodiversity. Gross Primary Production (GPP) is a measure of energy quantities fixed by autotrophic ecosystem components. There is significant debate as to the role of energy in influencing variation of ecosystem properties such as biomass, species richness, and rates of carbon storage. Here we focus on the key abiotic factors driving variation in both local and more global values of GPP. Traditionally, robust estimates of GPP have been elusive in absence of direct measurement. We utilize a large database from a global network of CO₂ flux monitoring sites, or FLUXNET. Yearly carbon exchange (NEE) was measured for 22 study sites in North America and Europe. The site group exhibits wide variation along several geographical and meteorological gradients. Within each site the relative influences of variation in temperature, precipitation, elevation, solar radiation, and seasonality, were estimated using a multivariate and regression techniques. Our analysis shows that a few critical abiotic features appear to be responsible for driving variation in ecosystem level processes. While several potential limiting factors vary systematically with latitude, it appears that temperature is dominant in ultimately determining ecosystem level fluxes including GPP. Together our results highlight the central biotic and abiotic features which govern the flux of carbon into terrestrial ecosystems. As such, our results have broad implications on effectively managing terrestrial carbon sinks and predicting future ecosystem behavior in an altered atmospheric state.

KEY WORDS: Gross Primary Productivity, Ecosystem Services