CARBON STOCK AND PHYSIOLOGICAL TRAIT VARIATION ACROSS A RAINFALL GRADIENT IN ROCKY MOUNTAIN FORESTS

Abstract

The Rocky Mountains are the second largest carbon sinks in the western U.S., yet how carbon stock and the traits that affect carbon stock change over a rainfall gradient needs further investigation. I will look at carbon stock and the functional traits affecting carbon, including \(^{13}\)C:\(^{12}\)C isotope ratio, leaf-to-shoot ratio, and specific leaf area in four forest types: piñon pine (Pinus edulis) – juniper (Junis osteosperma), ponderosa pine (Pinus ponderosa), trembling aspen (Quercus gambelii), and Engelmann spruce (Picea engelmannii). I will test how these traits and carbon stock vary across gradients of mean annual precipitation. I found that the forest’s carbon stock and functional traits respond on a community level rather than a species-specific level to rainfall changes. Only spruce forests show variation of carbon stock to rainfall, and only ponderosa forests show strong trait variation over the precipitation gradient. Performing a comprehensive analysis on the carbon storage and the traits that affect the carbon storage in the Rocky Mountain ecosystem indicates that climate extreme events are affecting one of the largest carbon sinks in the United States.