Modeling pre-settlement forests

[L]ike many areas of climate change science, but unlike most areas of ecology, the understanding of biosphere-atmosphere interactions fundamentally relies on the predictions of large, complex models whose parameters are difficult to measure, and that make predictions at scales far larger than we are typically able to make measurements. As a result, the findings of terrestrial biosphere modeling studies are usually appropriately couched in terms of potential feedback mechanisms. Indeed, a harsh, but not entirely unwarranted, view would be that our current understanding of biosphere-atmosphere feedbacks is a collection of interesting, but largely untested, hypotheses for the future state of terrestrial ecosystems and climate. – Moorcroft et al. (2006)

Objectives

The goal of PalEON is to allow data to inform our models of long-term ecosystem change. There are three fundamental objectives for bringing historical data and models together:

1. Validation – How do the models we use to predict future responses to climate change perform when confronted with past climate change? Are we able to capture dynamics correctly and, if not, can we understand why?
2. Inference – Paleo proxies only provide partial information about ecosystem dynamics, but models allow us to estimate the possible ranges for unobserved quantities that are consistent with the observed data. For example, what net carbon fluxes are compatible with an observed species composition and fire return interval? Estimates such as these provide a pre-settlement baseline from which we can judge current dynamics.
3. Initialization – Projections of the future are made conditioned on the present, but key ecosystem and biogeochemical variables, such as soil carbon, strongly reflect site history across centennial to millennial time scales. Due to an absence of data, equilibrium assumptions for model initialization are common, but are clearly untenable. Paleo-data provide the history necessary to understand the present and predict the future.

Modeling Teams

Below are the current project participants who are working together to design and implement the modeling protocols for PalEON.