USGS Submissions

The substantial distributional expansion and infill of pinyon (Pinus monophylla) and juniper (Juniperus sp.) trees (hereafter, "conifer") into sagebrush (Artemisia spp.) ecosystems 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 ecological consequences of the expansion are influenced by the proportion of coniferous cover within the ecosystem.

Understanding species status and forecasting range shifts for plants and animals requires accurate species distribution information, particularly at the margins of species ranges. However, most distribution studies rely on depauperate species occurrence datasets from herbarium records and public databases, along with statistically derived “pseudoabsences”. True absence data are rarely available. Most distribution analyses rely on statistical species distribution models (SDM).

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. Beyond the immediate impact on forests, such mortality events substantially increase the risk of catastrophic fires, which have the potential to change entire landscapes overnight.

Shrublands in southern California have seen sweeping changes in vegetation composition and structure due to fire and drought. Invasion of non-native grasses after repeated fire or drought events can inhibit shrub recovery and lead to vegetation type conversion to nonnative grassland. In California’s San Diego County, chaparral and coastal sage scrub vegetation communities are at risk, with some areas experiencing large declines in shrub cover.

Bird Conservation Regions (BCRs) are ecologically distinct areas with similar bird populations, ecological characteristics, and natural resource management concerns. Understanding vegetation distributions and dynamics may guide land management and conservation decisions, but current information available in the Sonoran and Mojave Deserts Bird Conservation Region (BCR 33) are insufficient due to the area’s low vegetative cover and complex vegetation communities, and the disconti

Fusing remote sensing products from different satellite sensors allows the development of enhanced maps of the distribution of coastal wetland plants and more accurate models of coastal elevations. This critical information about vulnerability to sea-level rise and hurricane flooding is being used by Department of Interior partners and State and local agencies to improve management in a changing climate.

Mercury is a neurotoxin and environmental pollutant that endangers the health of humans and wildlife. When mercury flows into aquatic environments like San Francisco Bay (SFB), it can be converted by microorganisms to methylmercury (MeHg), which is the most poisonous of mercury compounds. MeHg bioaccumulates in aquatic food webs and can cause a wide range of impairments in fish, birds, and humans.

The conversion of natural land cover to built-up surfaces has been widely documented as the main determinant of warming across urban areas, since buildings, roads, and other infrastructure absorb and reemit heat from the Sun more than natural landscapes. This land conversion process influences both canopy and surface urban heat intensities, resulting in urban heat islands (UHIs).

Fire perimeter databases provide critical geospatial information that land managers use for a variety of purposes, including documenting fire occurrence, determining historical reference conditions and fire regimes, planning fuels treatments and fire management operations, and assessing potential vulnerability of infrastructure and resources.

Tens of millions of trees reportedly died in California during the 2012–2016 drought, resulting in marked increases in heavy fuel loads on the landscape. In conjunction with warming temperature, drier conditions, and over a century of fire suppression, the accumulation of fuels can result in large fires that are beyond the predictive capacity of traditional fire behavior models. These extreme fires can cause an enormous amount of damage.