SYMP 8-6
The interplay between natural history and ecological science leads to successful forest and fisheries management
Theory in ecology has generally followed two paths. The first, a top-down approach, begins with simple theoretical assumptions expressed in standard mathematics borrowed from other fields (e.g. differential and integral calculus; matrix algebra) or simple mapped-based correlations (e.g. generalized maps of a species distribution overlaid on a climatic variable map). The other, a bottom-up approach, begins with fundamental biological observations (e.g. physiology, morphology) and with natural history observations. The majority of modeling and theory throughout the history of ecology has been of the first type. Problems with this type are well-known, including lack of validation, assumptions that are disconnected from reality, failure to make accurate forecasts.
My work has shown that models of the second type can be successful and overcome some of the limitations of the first type. In 2011, we validated a version of the JABOWA computer model of forest growth against the best forest-monitoring data we know of. The model projected 91.7% of the observed tree density, 92.3% of dbh, 82.8% of total tree height, 89.3% of the basal area, and 87.6%) of the aboveground biomass compared to the observed attributes. These results suggest that the model can provide reasonable capability in projecting growth dynamics of uneven-aged, mixed-species forests. Developed in 1970, versions of this model continue to be used widely in many parts of the world. This model was developed from natural history observations linked to experimental and field research in organic chemistry, biophysics, physiology, and morphology.
In the 1990s, I directed a study for the state of Oregon concerning the relative effects of forest practices on salmon. Although no existing fisheries model was doing well in forecasting temporal patterns in salmon abundance, Jim Welter, an old-time and long-experienced salmon fisherman and fishing guide with much natural-history knowledge but no formal training in mathematics, proposed that water flow would correlate closely with salmon returns four years later. Working with him, we showed that in fact 80% of the variation in salmon returns could be accounted for by prior water flow.
Results/Conclusions:
In short, the two examples and others I will discuss demonstrate that realistic, accurate forecasts have resulted from the combination of natural history and fundamental experimental and field research in basic biology. These models serve two purposes: to demonstrate the implications of existing empirical knowledge and provide accurate forecast.