Exploring spatial data in R

We will use forest inventory data from a long-term ecological research site in western Oregon (WEF). These data consist of a census of all trees in a 10 ha stand. Diameter at breast height (DBH) and tree height (HT) have been measured for all trees in the stand. For a subset of these trees, the distance from the center of the stem to the edge of the crown was measured at each of the cardinal directions. Rarely do we have the luxury of a complete census, but rather a subset of trees are sampled using a series of inventory plots. This sample is then used to draw inferences about parameters of interest (e.g., mean stand DBH or correlation between DBH and HT). We defer these analyses to subsequent example sessions. Here, we simply use these data to demonstrate some basics of spatial data manipulation, visualization, and exploratory analysis. We begin by removing rows that have NA for the variables of interest, creating a vector of DBH and HT, and plotting the tree coordinates.