Ecological Lessons Learned From the Fort Valley Experimental Forest

The Fort Valley Experimental Forest has contributed many long-term studies and ecological lessons to forest and range research since its inception in 1908. In 1909, T. S. Woolsey (Regional Forester) and G. A. Pearson (Director, Fort Valley) established a network of permanent sample plots in the ponderosa pine, mixed conifer, and spruce forest types throughout Arizona and New Mexico. We revisited many of the ponderosa pine-dominated plots and used ledger data, contemporary data, and dendrochronological techniques to quantify changes in species composition, tree density, and tree size over the past century. We used historical stem-maps to examine variations in tree spatial patterns over time as well. The Coulter Ranch site (24 plots) was part of the nation-wide Methods of Harvest study established in 1913. We examined the short- and long-term consequences of historical harvest method on contemporary pine forest structure and recruitment patterns at this northern Arizona site. In addition to the permanent forest plots, Fort Valley scientists established a series of range plots, known as Hill and Wild Bill, to examine the impacts of livestock grazing and increasing tree densities on herbaceous vegetation. The vegetation on the quadrats was mapped periodically between 1912 and 1941, and we continue to remeasure them today. Since plot establishment, understory abundance and diversity have declined and plant species have responded differentially to grazing and pine ingrowth. Currently, we are reconstructing stand structural dynamics from 1912 to present, and are quantifying litter decomposition rates and nitrification potential to determine how long-term vegetation changes have influenced ecosystem functioning. We are using these long-term forest and range plot data to increase our understanding of vegetation reference conditions, and to quantify the influence of climate and land-use changes on the ponderosa pine ecosystems of the Southwest