Using eDNA and remote sensing to quantify species diversity, functional diversity, and their environmental drivers along an agricultural-riparian gradient

Background/Question/Methods

Riparian buffers, such as those found in California’s San Joaquin Valley, provide a multitude of ecosystem functions and services. These functions include providing habitat for plant, animal, and insect species, nutrient and sediment filtering, and additions of organic matter to soils. While the biodiversity subsidies and ecosystem services of riparian buffers are known, due to the complexity of collecting species data across taxa, the exact benefits have been difficult to quantify. The emergence of eDNA and remote sensing as tools for biodiversity monitoring presents an opportunity to evaluate species diversity across the eukaryotic spectrum at the community level. Our study collected 64 eDNA samples and soil samples along 16 transects, distributed over a 150 m gradient between an abandoned maize field and a riparian buffer zone in California’s San Joaquin Valley. This data will be augmented by 3D canopy measurements derived using UAV flights over the transects and satellite imagery from Planet SuperDove and Sentinel-2. Links between alpha, beta, zeta, and functional diversity will be compared to environmental and biogeochemical parameters along the transects to elucidate new insights into biodiversity and ecosystem function along agricultural-riparian gradients.

Results/Conclusions

It is expected that species diversity and functional diversity will decline moving across the riparian zones to agricultural zones. However, we also expect that there will also be shared species along the transects that provide ecosystem functions in both systems. If this is true, this will provide further credence for conservation of existing ecologically functional buffer zones in agroecosystems and reestablishment of historic riparian buffer zones. This dataset will also serve as a baseline assessment of an agricultural-riparian gradient prior to restoration of the agricultural sites to riparian habitats, which can be used to evaluate the efficacy of riparian restoration efforts in California’s San Joaquin Valley.