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.