Incorporation of Precipitation Data Into FIA Analyses: A Case Study of Factors Influencing Susceptibility to Oak Decline in Southern Missouri, U.S.A.This article is part of a larger document. View the larger document here.
The Forest Inventory and Analysis program at the North Central Research Station focuses on understanding the forested ecosystems in the North Central and Northern Great Plains States through analyzing the results of annual inventories. The program also researches techniques for data collection and analysis. The FIA process measures the above-ground vegetation and the site (soils) factors, but not climatic data. This pilot study, centered around three inventory units in southern Missouri, assigned weather data obtained from the National Oceanic and Atmospheric Administration to particular forest inventory plots, based on nearest distance. We incorporated precipitation and maximum and minimum temperatures into a temporary database, then analyzed the growth and forest health data for the plots for any relationships among the climate data. We found an apparent relationship between precipitation and the hypothesized relationship between the variables believed to predispose the stand toward oak decline and mortality variables, particularly in larger, older trees. Adding precipitation as an independent variable helped increase the quality of the predictions of the mortality models in situations where we concentrate on size/age groups more prone to forest health problems. Finally, we found evidence of spatial patterns of precipitation across the Ozark Plateau in southern Missouri that appear to be correlated with landscape-level patterns of mortality. Management activities need to address the role of the predisposing variables in influencing susceptibility to oak decline. As the level of precipitation seems to exacerbate the predisposing variables? effects, historical patterns of rainfall and soil moisture retention need to be taken into account when regenerating and managing oak forests in the Missouri Ozarks.