A multidecadal metric of coastal wetland stability: Development of the Landsat-based UnVegetated-to-Vegetated Ratio (UVVR) version 2 spanning 1985-2022

Abstract

The UnVegetated-to-Vegetated Ratio (UVVR) is a well-established metric of wetland condition, identifying stable wetlands with high vegetation cover and low vegetation cover wetlands prone to loss, informing research and management efforts in the coastal zone. In this study, we document the development and release of version 2 of UVVR (UVVR v2 ) for the coastal conterminous United States. UVVR v2 was derived from Landsat Collection-2 satellite imagery providing increased image consistency and geolocation accuracy. We describe several UVVR v2 updates including expanding the product record from 2014–2018 to 1985–2022 and improved calibration of spectral indices used to estimate fractional cover. We validated UVVR v2 and UVVR v1 against the MODIS Vegetation Continuous Field (VCF) products and demonstrate that UVVR v2 agrees well with VCF vegetation cover across the Atlantic, Gulf, and Pacific Coasts, with R 2 > 0.82 and root mean square errors (RMSEs) < 0.18 over five years. Relative to the UVVR v1 , UVVR v2 showed increases in R 2 > 0.29 and reductions in RMSEs > 0.12. Moving beyond metric development, we present several examples of UVVR v2 applications including multidecadal vegetation cover trend maps for various coastal wetland systems. Our findings demonstrate an increased ability to characterize wetland condition with Landsat Collection-2 imagery, and indicate that upcoming missions (e.g., Landsat Next) could result in further characterization improvements. Overall, UVVR v2 helps advance coastal wetlands monitoring and management efforts due to increased accuracy and longer period-of-record.