Many ecosystems are facing increases in climate variability, as well changes in average temperature and precipitation. However most empirical research has focused on ecological responses to changes in average climate, rather than climate variability. Environments that already experience high levels of variability, like arid rivers, offer insight into how climate variability can influence plant growth. We explored the relationships between plant cover and environmental variables for several riparian tree species to build predictions about how increased environmental variability could affect riparian ecosystems.
We used long term data from the Middle Rio Grande in New Mexico that had been collected by botanists and community scientists in grades K-12 across the last 20 years as part of the Bosque Ecosystem Monitoring Program (BEMP). BEMP trains students to collect groundwater, precipitation, and vegetation data that are then used by land managers. By involving students directly in data collection and analysis, BEMP has included tens of thousands of students in environmental stewardship on their local lands while maintaining a continuous datasets for 33 sites over 20 years. We paired the community science data with vegetation surveys conducted by botanists at the same sites. Using the large variation across time and space can improve predictions about how plants will respond to future climate variability at a regional scale.
Results/Conclusions
Riparian plant cover was correlated with water table depth, which is largely driven by changes in stream flow. Of the several tree species we looked at, each had a different shape to the environmental sensitivity function, suggesting that species will diverge in responsiveness to future variability in groundwater depths, likely due to differences in life history traits. Rio Grande cottonwoods are predicted to respond negatively to increased groundwater variability, but only at high temperatures. In contrast, coyote willow, a wetland shrub, is predicted to benefit from variability. Non-native species had either no relationship or a linear relationship with groundwater depth, indicating low to no sensitivity to climate variability. Our results show that it is important to explore how plants respond to climate variability, and that the relationships between growth and variability are complicated by plant traits and interactions between environmental variables such as water availability and temperature. They also demonstrate that K-12 community science data gathered across decades can provide robust information.