Sonoran Desert Ecological Conservation: Identifying and Mapping Category 1 Invasive Species in the Sonoran Desert in Southern Arizona Using Harmonized Landsat and Sentinel Data

Buffelgrass (Cenchrus ciliaris) is an invasive perennial grass that is especially pervasive in the Sonoran Desert, located in the southwestern United States and northern Mexico. Saguaro National Park, Tumacácori National Historical Park, and the surrounding Pima and Santa Cruz Counties in Arizona are managing large-scale infestations of buffelgrass, which outcompete native vegetation and increase the risk and severity of wildfires, damaging the ecosystem and threatening the local community. This project aims to test the feasibility of using remote sensing to predictively map the spread and distribution of buffelgrass, as an alternative to other costly and time-consuming methods. We used Multi-Source Land Imaging (MuSLI) data for 2016-2019 and Normalized Difference Vegetation Index (NDVI) & Modified Soil Adjusted Vegetation Index 2 (MSAVI2) data derived from Harmonized Landsat-Sentinel (HLS) imagery to identify buffelgrass locations after significant rain events from 2016-2024. In addition, we created two habitat suitability models that may help identify where buffelgrass exists, and where it could spread. Our study showed no relationship between green-up identified using HLS-based MuSLI, NDVI, and MSAVI2 images and known locations of buffelgrass. More research and robust data are needed to determine the feasibility of multispectral imagery to be used as a method of identifying buffelgrass. Our Saguaro National Park suitability model aligned well with known buffelgrass points. The mean suitability values of the known points were 7.13, on a scale of 1-10. Both habitat suitability models of the park and entire study area, will allow partners to identify areas most susceptible to buffelgrass infestations, which may support ongoing management efforts to control buffelgrass.