Sack Lunch Seminar (SLS)

Seeing the forest AND the trees: Modeling ecosystem-climate interactions

Ecosystems are dynamic systems that govern biogeochemical cycling and are intrinsically tied to climate. To understand ecosystem-climate interactions and feedbacks, we must understand both the mechanisms by which individual organisms respond to the environments they experience, and the processes through which these fine-scale responses result in large-scale ecosystem shifts. An ecosystem model that represents both fine-scale (spatial and temporal) and stochastic processes on regional to global scales is used to investigate trends in above-ground biomass dynamics in the Amazon rainforest. Plant water stress at the scale of the individual is shown to play an important role in determining emergent ecosystem properties such as variations in forest structure, composition and function across the basin. By not capturing fine scale ecosystem dynamics, conventional terrestrial ecosystem models are missing fundamental ecological mechanisms that provide tropical forests with resiliency to changes in climate.

The impact of climate perturbations and change on marine ecosystems are similarly determined by responses at the scale of the individual, responses that are not currently captured by global marine ecosystem models. I outline an approach to use the demography methods developed within the framework of terrestrial carbon cycling to link temporal and spatial scales in an ocean ecological and biogeochemical model. This model will provide new insight into the mechanisms driving marine biogeochemical transformations, and the sensitivity of marine microbial ecosystems to climate variability.