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Vegetation

Vegetation refers to plant life, including agricultural and developed vegetation, desert and semi-desert, forest, shrubs, herbs, and natural land cover. Drought can result in reduced growth rates, increased stress on vegetation, and alterations or transformations to the plant community and/or the entire ecosystem.

Vegetation and Drought

Tall, green trees with a mountain in the background

Water is necessary for every aspect of plant development, including gemination, cell division, and respiration. The stress of drought may induce complex changes in biochemical, physiological, and morphological aspects of plants, limiting vegetative health, growth, regeneration of the plant population, the vegetative community in a region, and/or the entire ecosystem. The exact nature of impacts to vegetation depends on the drought—its severity, spatial extent, seasonal timing, and persistence, and the capacity of the vegetation to absorb and adapt to disturbances, and vegetation management actions.

Data, Maps, and Tools

During periods of drought, plants increase their demand for water through increased evapotranspiration and longer growing seasons.

U.S. Vegetation and Drought

The Evaporative Stress Index (ESI) describes temporal anomalies in evapotranspiration (ET), highlighting areas with anomalously high or low rates of water use across the land surface. The ESI also demonstrates capability for capturing early signals of "flash drought," brought on by extended periods of hot, dry, and windy conditions leading to rapid soil moisture depletion. Learn more.

The Vegetation Drought Response Index (VegDRI) is a weekly depiction of drought's effects on vegetation stress across the contiguous United States, produced by the National Drought Mitigation Center, the U.S. Geological Survey’s National Center for Earth Resources Observation and Science, and the High Plains Regional Climate Center. Learn more.

NOAA's Center for Satellite Applications and Research produces satellite-based global vegetation health products, including the vegetation health index (VHI). VHI is a proxy characterizing vegetation health or a combined estimation of moisture and thermal conditions. Vegetation health is often used to estimate crop condition and anticipated yield. If the indices are below 40, indicating different levels of vegetation stress, losses of crop and pasture production might be expected; if the indices above 60 (favorable conditions), plentiful production might be expected. Learn more.

Standardized ET/PET Anomolies
Value Map Hex Color
-2σ < #722700
#ea0500
-1σ #fc762d
#f9d26d
0 #fff
#ddfe93
+1σ #a0f447
#42cb01
> +2σ #1c7001
Drought Conditions
Value Map Hex Color
Pre-Drought Stress #ffe500
Moderate Drought #e66900
Severe Drought #c81e32
Extreme Drought #6b0000
Moist Conditions
Value Map Hex Color
Unusually Moist #87fac2
Very Moist #53c289
Extremely Moist #288233
Other Conditions
Value Map Hex Color
Near Normal #fff
Out of Season #b2b2b2
Water #0070fd
Other Landcover #828282
Unfavorable Conditions
Value Map Hex Color
0 - 6 #ff00a0
6 - 12 #f00050
12 - 24 #ff7878
24 - 36 #ffaa00
36 - 48 #ff5
Favorable Conditions
Value Map Hex Color
48 - 60 #5f5
60 - 72 #0a0
72 - 84 #55f
84 - 100 #00a

Related Content

Data & Maps | Soil Moisture

Drought can affect soil chemical, physical, and biological activities that are essential for plant and soil health. Impacts may include lack of nutrient uptake by vegetation, increased soil temperatures, altered microbial activity, changes in organic matter decomposition, and increased release of CO2.

Data & Maps | Agriculture

In agricultural ecosystems, drought may affect the growth rate and development of crop production. Without irrigation, drought-induced crop losses may be extensive, resulting in significant economic losses.

Data & Maps | Fire

Drought stress on vegetation can include damage to forests and soils, which in turn may increase wildfire frequency, severity, and spatial extent. View datasets and maps on current and predicted outlooks for fire risk, potential, and occurrence.

Research & Learn | Ecological Drought

Ecological drought refers to extreme drought impacts that exceed the capacity of both human and natural systems to adapt. Thus, ecological drought could drive irreversible changes in vegetation ecosystems—for example, from forest to shrubs—thereby changing the ecosystem benefits and services once provided by forests.