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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.

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    • 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
    Evaporative Stress Index VegDRI Vegetation Health Index

    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

    The color with the hex code #722700 identifies:
    -2σ <
    The color with the hex code #ea0500 identifies:
    The color with the hex code #fc762d identifies:
    -1σ
    The color with the hex code #f9d26d identifies:
    The color with the hex code #fff identifies:
    0
    The color with the hex code #ddfe93 identifies:
    The color with the hex code #a0f447 identifies:
    +1σ
    The color with the hex code #42cb01 identifies:
    The color with the hex code #1c7001 identifies:
    > +2σ

    Drought Conditions

    The color with the hex code #ffe500 identifies:
    Pre-Drought Stress
    The color with the hex code #e66900 identifies:
    Moderate Drought
    The color with the hex code #c81e32 identifies:
    Severe Drought
    The color with the hex code #6b0000 identifies:
    Extreme Drought

    Moist Conditions

    The color with the hex code #87fac2 identifies:
    Unusually Moist
    The color with the hex code #53c289 identifies:
    Very Moist
    The color with the hex code #288233 identifies:
    Extremely Moist

    Other Conditions

    The color with the hex code #fff identifies:
    Near Normal
    The color with the hex code #b2b2b2 identifies:
    Out of Season
    The color with the hex code #0070fd identifies:
    Water
    The color with the hex code #828282 identifies:
    Other Landcover

    Unfavorable Conditions

    The color with the hex code #ff00a0 identifies:
    0 - 6
    The color with the hex code #f00050 identifies:
    6 - 12
    The color with the hex code #ff7878 identifies:
    12 - 24
    The color with the hex code #ffaa00 identifies:
    24 - 36
    The color with the hex code #ff5 identifies:
    36 - 48

    Favorable Conditions

    The color with the hex code #5f5 identifies:
    48 - 60
    The color with the hex code #0a0 identifies:
    60 - 72
    The color with the hex code #55f identifies:
    72 - 84
    The color with the hex code #00a identifies:
    84 - 100
    Source(s):

    NASA SERVIR
    Source(s):

    NDMC, USGS, HPRCC
    Source(s):

    NOAA STAR
    Last Updated  -  03/09/21
    Updates Weekly  -  04/06/21
    Updates Weekly  -  03/24/21
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    Data and Map Gallery

    Monitoring vegetation productivity responses to drought variability over a large spatial extent is generally aided by remote sensing approaches, particularly in areas with sparse climate and vegetation monitoring stations (El-Vilaly 2018). Below are resources to monitor drought effects on vegetation, access indices describing evaporative demand and stress, and consult maps depicting vegetation health, greenness, drought severity, and more.

    VegDRI map of the contiguous U.S.

    Vegetation Drought Response Index (VegDRI)

    VegDRI: a weekly depiction of vegetation stress across the contiguous United States.

    Period of Record
    2009 - Present
    File Format
    images
    pdf
    NDVI greenness map example

    NDVI Greenness Maps

    NOAA Center for Satellite Applications and Research (STAR) normalized difference vegetation index (NDVI) maps

    Period of Record
    2000 - Present
    File Format
    geotiff
    kml
    CDSI example image

    U.S. Forest Service Cumulative Drought Severity Index (CDSI)

    U.S Forest Service Cumulative Drought Severity Index (CDSI): allows users to compare the severity of droughts experienced by different forest ecosystems between two periods, 1960-1986 & 1987-20

    Period of Record
    1960-1986, 1987-2013
    File Format
    images
    geotiff
    NOAA Global Vegetation product example map

    NOAA Global Vegetation Products

    A selection of worldwide maps monitoring different aspects of vegetation health.

    Period of Record
    Current Conditions, Historical data (period of record varies)
    File Format
    images
    Example NDVI map

    NOAA STAR Global Vegetation Health Products

    Global and Regional Vegetation Health (VH) is a NOAA/NESDIS system estimating vegetation health, moisture condition, thermal condition and their products.

    Period of Record
    1981 - Present
    File Format
    images
    geotiff
    netcdf-4
    Example PDSI map in Climate Engine

    Climate Engine

    Climate Engine allows users to analyze and interact with climate and earth observations for decision support related to drought, water use, agricultural, wildfire, and ecology.

    Period of Record
    Current Conditions, Historical data (period of record varies)
    File Format
    images
    pdf
    csv
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    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.

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    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.

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    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.

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    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.

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    Vegetation Research and Resources

    Peer-Reviewed Publications
    Web Resources

    Remote Sensing Phenology
    U.S. Geological Survey

    ECOSTRESS
    NASA Jet Propulsion Laboratory

    Monitoring Vegetation Drought Stress
    U.S. Geological Survey

    Effects of Drought on Forests and Rangelands
    U.S. Department of Agriculture

    How Drought Affects Your Forest
    American Forest Foundation