Vegetative and environmental characteristics of high elevation riparian communities in the mountains of southeastern Arizona

Abstract

Fifteen canyons in the Coronado National Forest, in southeastern Arizona were sampled in order to study the woody riparian overstory. Vegetative and environmental data were collected from 99 high elevation (>1050 meters) sites within these canyons that had a woody riparian overstory. Vegetative data included abundance and diameter at breast height (DBH) of each woody tree, and abundance and root collar diameter of each woody shrub in the sample plot. Environmental site data included elevation, stream gradient, stream width and depth, terrace height, stream direction, and watershed area. The vegetative data for each site were classified into one of six possible community types using an average linkage/euclidean distance clustering algorithm. Clustering was performed using DBH data and abundance data in order to compare the two types of approaches. This study suggests that in high elevation areas, typical riparian community vegetation include shrub species such as Baccharis and Robinia, as well as facultative upland species such as Abies, Acer, Juniperus and Ouercus. Platanus and Salix are also commonly found, while Populus is rare. The environmental data were summarized by community type. Binary recursive partitioning was used to produce a classification structure to determine which environmental variables were most effective to differentiate between the communities and the larger sample set. Elevation and stream gradient were the most important parameters when measuring communities by their relative abundance. Elevation was the most important parameter when measuring communities by DBH.