Submitted by Albert Ruhi Vidal on
The flux of leaf litter from the riparian zone is a major energy pathway into streams, and, thus, litter breakdown is a critical ecosystem-level process affecting both the carbon and nutrient cycles as well as stream food webs. Leaf litter decomposition is influenced by litter quantity and quality (i.e., physical and chemical components) and riparian phenology (i.e., the timing of leaf abscission), both of which are driven by climate. Climate—particularly temperature and precipitation—controls the composition of riparian vegetation, the amount of leaf biomass input, leaf litter chemical composition, and the timing of leaf abscission. Specifically, drought has been shown to decrease riparian leaf litter quality via higher C:N ratios and reduced leaf N and P. Drought can also lead to earlier leaf abscission. In turn, leaf quality, quantity, and phenology can vary across intermittent stream networks where water availability varies spatially and seasonally.
This study seeks to partition out the multiple, interacting effects of water availability on leaf litter decomposition via (a) influencing leaf litter quality, (b) shaping invertebrate assemblages, and (c) controlling stream hydroperiods. We will run a leaf litter bag experiment to assess leaf litter quality, stream invertebrate community structure, and decomposition rates across a gradient of flow intermittency.
Students will prepare leaf litter samples for chemical composition analysis (e.g., drying, grinding, and weighing samples on a microbalance). Finally, students will also sort and identify macroinvertebrates. If interested, students will have opportunities to perform fieldwork in Pinnacles National Park to deploy the leaf litter bags and sample invertebrates.
No prior experience is required, but skills or coursework in aquatic ecology, entomology, plant ecophysiology, hydrology, or field research techniques are advantageous. Students will be trained in macroinvertebrate sorting and identification at the beginning of the semester. While participation in fieldwork for this project is not mandatory, students that choose to participate should be able to carry 30+ lbs for up to 10 miles in a single day.