Woodworth, K. (2021). Effects of Ditching on Soil Structure and Vegetation Community in Two Subalpine Fens.

Fens are perennially wet, groundwater-dominated ecosystems that provide vital refugia for native species during the summer dry season in California, sequester organic carbon, and filter groundwater. This study focused on the impacts of manmade drainage ditches on soil structure and wetland-dependent vegetation in alpine fens in the Childs Meadow complex, an ongoing restoration site in the Lassen National Forest in California. Sample quadrats were located above (upslope) and below drainage ditches in two fen locations within the complex. In each quadrat, soil horizons down to 60 cm were sampled via auger, classified as mineral or organic based on organic carbon content, and analyzed for texture, color and depth to groundwater. Percent cover of representative fen-obligate mosses was estimated in each 40 by 40 cm quadrat. Above-ditch sites had considerably wetter soils with higher organic matter content, as well as greater percent cover of moss. Below ditch sites had reduced organic carbon content, increased grass cover, and greater depth to groundwater. Our results highlight the negative impacts of drainage ditches on soil organic carbon content and wetland plant cover in alpine meadows and provides a baseline of soil and vegetation conditions in two impacted fens in Childs Meadow. This work will be used to guide future restoration of Childs Meadow fens, as well as provide insight into how these fragile ecosystems might recover over time.