Climate and Land Use Change
The 64,000-square mile watershed that drains to the Chesapeake Bay is highly populated and has diverse land use, including forested, agricultural, and urbanized areas. Increased precipitation in the eastern United States over the last 100 years has affected stream flow and thus the loading of pollutants delivered to the bay. Such pollutants as suspended sediment and dissolved phosphorus and dissolved nitrogen enter the bay and cause environmental problems. These problems include rapid growth of algae because of the abundance of nutrients (nitrogen and phosphorus), causing huge areas of the bay to be covered in “algal blooms.” Once these algae die, they sink and decompose, using dissolved oxygen in the water to decompose. The use of dissolved oxygen for decomposition depletes the water of this essential gas, which is needed for other aquatic life. The result is “dead zones” in the bay, that is, areas of the water where there is no oxygen, technically termed anoxic. Suspended sediment delivered to the bay during high stream discharge events blocks sunlight to submerged aquatic vegetation (SAV), which need sunlight to grow.
The retreat of glaciers in Glacier National Park, Montana, has received widespread attention by the media, the public, and scientists because it is a clear and poignant indicator of change in the northern Rocky Mountains of the USA. In 2017 the USGS and partner, Portland State University, released a dataset which describes the areas of the 37 named glaciers in Glacier National Park and two glaciers on the U.S. Forest Service’s Flathead National Forest land. The areas are described for 1966, 1998, 2005 and 2015/2016, marking 49 years of change for most of the glaciers and 50 years of change for a few. The difference in record length is due to adequate satellite data not being available for a few glaciers in 2015.
The simulation reflects the predicted exponential rise in atmospheric CO2 concentrations, a 2xCO2 "global warming" scenario, by 2030 with a concurrent warming of 2-3 degrees centigrade (4-5 degrees Fahrenheit) by the year 2050. In addition it assumes that precipitation, primarily during the winter, will increase over the same time period five to 10 percent. The animation view of the Blackfoot-Jackson basin along the Continental Divide, includes Gunsight Lake in the foreground and a portion of Lake Ellen Wilson visible over Gunsight Pass.
USGS scientists have been involved for a number of years in the development and use of Structural Equation Modeling (SEM). This methodology represents an approach to statistical modeling that focuses on the study of complex cause-effect hypotheses about the mechanisms operating in systems. SEM is increasingly used in ecological and environmental studies and this site seeks to provide educational materials related to that enterprise. This site serves up tutorials, exercises, and examples designed to help researchers learn and apply SEM. Please click on the “Science” tab to learn more.
Long-term monitoring data in the Manatee Individual Photo-identification System (MIPS), developed and coordinated by WARC-Sirenia Project in collaboration with Florida’s Fish and Wildlife Research Institute and Mote Marine Laboratory, are the basis for modeling manatee demography rates.
The Challenge: Accelerations in sea-level rise and changing environmental stressors have important implications for the integrity of coastal wetlands and for efforts to restore and protect the ecosystem services they provide. Their persistence and adaptation to these stressors depends on the net effects of changes in physical processes and biotic responses. Future planning by decision makers will require scientifically sound forecasts of potential impacts, knowledge of sea-level rise thresholds, and indications of the potential effectiveness of various adaptation strategies.
High-severity crown fires in Southwestern dry-conifer forests — resulting from fire suppression, fuel buildups, and drought — are creating large treeless areas that are historically unprecedented in size. These recent stand-replacing fires have reset extensive portions of Southwest forest landscapes, fostering post-fire successional vegetation that can alter ecological recovery trajectories away from pre-fire forest types toward persistent non-forested ecosystems (shrublands and grasslands). Our team studies areas that burned during the recent persistent regional drought (ca. 1996-2014) that are recovering under "hotter drought" conditions that foreshadow projected future climate trends. Our field surveys document a wide variety of post-fire ecological responses following stand-replacing crown fires in diverse forest settings, including potential "type conversion" to non-forest. These research results improve understanding of Southwest landscape changes in response to land use and climate, contributing to informed land management decisions regarding adaptation or mitigation strategies to sustain forests under projected “hotter drought” conditions.
Tropical storms and hurricanes wreak havoc with coastal forests where damage can vary with wind speed and approach from isolated treefalls to wide-area blowdowns of whole forests.
Critical information predicting condition changes in manatee habitat resulting from the alteration of freshwater flows to estuaries is needed to develop the PSRP Detailed Design and PSRP Operations Plan components and complete consultation under the Endangered Species Act.
The Challenge: The high winds and storm surge associated with Hurricane Sandy impacted coastal wetlands from Virginia to Maine. Understanding the ecological and geological impacts of hurricanes on coastal wetlands and their interactive effects with local conditions is important for identifying resilience of these communities to predicted global sea-level rise. Given the projected increase in number and intensity of hurricanes, we need to understand the impact of physical and chemical stressors associated with hurricanes in order to efficiently and effectively protect and restore these critical habitats. Storm-related sediment deposition and erosion are two of the potential long-term impacts of severe storms such as Hurricane Sandy on marsh surface elevation and resilience. But wetland impacts are unique for every major storm because of each storm’s unique characteristics (wind speed, angle of approach, tidal stage).
The National Park Service (NPS) manages the Nation’s most iconic destinations that attract millions of visitors from across the Nation and around the world. Trip-related spending by NPS visitors generates and supports a considerable amount of economic activity within park gateway communities. USGS economists collaborate with the National Park Service social science program to estimate NPS visitor spending and associated economic contributions to local and national economies.
Playas in the Great Plains Landscape Conservation Cooperative (GPLCC) are at risk for both increased sedimentation and reduced inundation due to predicted increased summer temperatures, decreased annual precipitation, and agricultural intensification. Among other benefits, playas provide essential habitat for many wetland-dependent species and are especially important as critical refueling stops during spring and fall waterfowl and shorebird migrations. Increasing occurrence of summer drought also potentially threatens the persistence of breeding short grass prairie birds within the GPLCC boundaries.