USGS Submissions

Scientists have effectively monitored vegetation dynamics using remotely sensed time-series vegetation index (VI) data for several decades.

The Colorado River delta riparian vegetation has been declining since 2000 as measured by Landsat. USGS scientists used the two-band Enhanced Vegetation Index (EVI2) as a proxy for greenness and as an input to calculate actual evapotranspiration (ETa, mmd-1). Restoration initially started in 2010 and has become more widespread and successful in recent years since 2019.

California recently experienced one of the most severe droughts in its history, resulting in extensive dieback of chaparral vegetation in the State’s Mediterranean regions. Though chaparral species are adapted to annual summer drought, the duration or intensity of a drought may exceed the adaptive capabilities of even these plants.

The substantial distributional expansion and infill of pinyon (Pinus monophylla) and juniper (Juniperus sp.) trees (hereafter, "conifer") into sagebrush (Artemisia spp.) ecosystems in Nevada and northeastern California since the late 1800s threatens the ecological function and economic viability of these ecosystems and represents a major contemporary challenge facing land and wildlife managers.

The intensification of drought across the Colorado River Basin is causing riparian ecosystem stress and transformations in plant stand structure, species composition, and plant water use, resulting in increasing resource management challenges.

Accurate maps of seasonal habitat for greater sage-grouse (Centrocercus urophasianus) are of paramount importance to conservation efforts in sagebrush ecosystems across the Great Basin, particularly for habitat assessments and mitigation efforts.

Human water use that alters river flow can shape ecology and biodiversity in many riverine and associated environments. Population viability is often linked to the timing and extent of floodplain and wetland inundation, and disruptions to historical flow regimes can have major impacts on species that have difficulty adapting to altered environments.

In recent decades, forests worldwide have experienced dramatic and often unexpected drought-related tree mortality events. California recently suffered its most extreme drought on record, resulting in the deaths of tens of millions of trees.

Shrublands in southern California have seen sweeping changes in vegetation composition and structure due to fire and drought. Invasion of nonnative grasses after repeated fire or drought events can inhibit shrub recovery and lead to vegetation type conversion to nonnative grassland.

Rangeland ecosystems in the western United States (U.S.) are vulnerable to climate change, fire, and anthropogenic disturbances, yet available geospatial data for assessing trends in condition or fire risk, for example, may not be sufficient to inform management practices.