Variation in biocrust photosynthesis

Desert mosses experience long periods of drying interrupted by brief windows of hydration, making photosynthesis highly dependent on when, where, and how water becomes available. This project examines how biocrust-forming mosses vary in photosynthetic traits across desert environments that differ in precipitation seasonality, temperature, and atmospheric drying demand. We are especially interested in whether seasonal shifts in photosynthetic performance reflect flexible physiological plasticity, longer-term differentiation among populations, or some combination of both. Using field collections, controlled growth experiments, pigment analyses, and chlorophyll fluorescence approaches, this work asks how desert mosses balance carbon gain with protection from excess light, heat, and drought. By comparing natural variation with responses under shared growth conditions, we aim to better understand how much of this variation is environmentally responsive and how much may reflect fixed differences among populations. This project contributes to broader efforts to predict how changing precipitation regimes and warming may affect biocrust carbon balance in dryland ecosystems.