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Ecosystems

Drought can alter the ecological balance of natural systems and harm fish, wildlife, and plant species, as well as the services that these ecosystems provide to human communities.

Ecological Regions in Drought

Ecological regions (ecoregions) are areas of general similarity in ecosystems and in environmental resources. They serve as a spatial framework for the research, assessment, management, and monitoring of ecosystems and ecosystem components.

This map shows forest ecoregions from EPA's Level 1 Ecoregions of North America, alongside drought conditions from the U.S. Drought Monitor.

This map shows prairie ecoregions from EPA's Level 1 Ecoregions of North America, alongside drought conditions from the U.S. Drought Monitor.

This map shows desert ecoregions from EPA's Level 1 Ecoregions of North America, alongside drought conditions from the U.S. Drought Monitor.

This map shows Mediterranean ecoregions from EPA's Level 1 Ecoregions of North America, alongside drought conditions from the U.S. Drought Monitor.

U.S. Forests in Drought

The color with the hex code #006600 identifies:
Forests

U.S. Prairies in Drought

The color with the hex code #663399 identifies:
Prairies

U.S. Deserts in Drought

The color with the hex code #663333 identifies:
Deserts

U.S. Mediterranean Regions in Drought

The color with the hex code #339999 identifies:
Mediterranean

U.S. Drought Monitor Categories

The color with the hex code #ffff00 identifies:
D0
The color with the hex code #ffcc99 identifies:
D1
The color with the hex code #ff6600 identifies:
D2
The color with the hex code #ff0000 identifies:
D3
The color with the hex code #660000 identifies:
D4
Last Updated  -  02/10/20
Last Updated  -  02/10/20
Last Updated  -  02/10/20
Last Updated  -  02/10/20
10,274,679
acres burned in 2020
5,110
flood events since January 1, 2020
99.5 Million
acres of forest in Severe Drought (D2 - D4)
167.6 Million
acres of prairies in Severe Drought (D2 - D4)
Key Issues

Ecological Drought

Drought can impact natural ecosystems and the services they provide to human communities.

Integrated Planning

Natural ecosystems and their benefits should be incorporated into future planning for drought impacts.

Drought Impacts on Ecosystems

Historically, drought has been viewed in terms of its agricultural, hydrological, and socioeconomic impacts—how drought affects ecosystems and the services they provide to human communities was often not discussed. The term ecological drought has been employed relatively recently to capture this emphasis on how drought impacts ecosystems. It encompasses and emphasizes the environmental consequences of drought, which include losses in plant growth; increases in fire and insect outbreaks; altered rates of carbon, nutrient, and water cycling; and local species extinctions.

It’s important to note that the concept of ecological drought does not exclude humans from the equation. Rather, it recognizes that the relationship between humans and ecosystems in the context of drought is closely linked. For example, an ecosystem that has been significantly altered by human development is now more vulnerable to drought than it once was for a variety of reasons, including increased competition for water resources.

When a drought occurs, the existing pressures on the ecosystem’s natural water supplies are amplified. If the ecosystem’s water needs aren’t considered in water allocation decisions, then this already vulnerable ecosystem may be pushed beyond the threshold at which it can recover. The ecosystem will begin to function differently, leading to a loss in the critical services it once provided humans—such as purifying water and air, preventing erosion, and providing recreation opportunities. This shows how human and natural systems influence each other in the context of drought and demonstrates the real value of considering the water needs of ecosystems and the effects of human water and land use on ecological water supplies.

The U.S. Geological Survey (USGS), through its regional Climate Adaptation Science Centers, has led early efforts to examine ecological drought across the country. Its Ecological Drought initiative supports the management of ecosystems and human communities in the context of drought. To help meet this aim, the SNAPP Ecological Drought Working Group, which NIDIS was a part of, focused on understanding the natural and human dimensions of ecological drought impacts, and promoting the application of solutions that provide mutual benefits to people and nature. NIDIS is funding a project that seeks to better understand ecological impacts of droughts by strengthening our understanding of ecological drought vulnerability and translating and delivering that information for drought planning processes.

Drought Early Warning for the Ecosystems Sector

Drought early warning is essential to prepare for and mitigate the ecological impacts of drought. The resources below are organized by the key components of a drought early warning system: (1) drought observation and monitoring; (2) drought planning and preparedness; (3) prediction and forecasting of drought; (4) communication and outreach to the public and affected sectors; and (5) interdisciplinary and applied research on topics of concern to drought-affected sectors.

Related Content

Data & Maps | Vegetation

Drought can result in reduced growth rates, leaf loss, and increased stress on vegetation. Visit this page to view data, maps, and tools that monitor and forecast drought's effects on vegetation.

Research & Learn | Ecological Drought

Healthy ecological systems support every form of life, and drought can alter or degrade critical ecosystem functions and services. Learn more about ecological drought here.

Research & Learn | Flash Drought

Flash drought can quickly deplete soil moisture and dramatically increase evaporative stress on the environment. Learn more about flash drought here.