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
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.
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.
| Value | Map Hex Color |
|---|---|
| -2σ < | #722700 |
| #ea0500 | |
| -1σ | #fc762d |
| #f9d26d | |
| 0 | #fff |
| #ddfe93 | |
| +1σ | #a0f447 |
| #42cb01 | |
| > +2σ | #1c7001 |
| Value | Map Hex Color |
|---|---|
| Pre-Drought Stress | #ffe500 |
| Moderate Drought | #e66900 |
| Severe Drought | #c81e32 |
| Extreme Drought | #6b0000 |
| Value | Map Hex Color |
|---|---|
| Unusually Moist | #87fac2 |
| Very Moist | #53c289 |
| Extremely Moist | #288233 |
| Value | Map Hex Color |
|---|---|
| Near Normal | #fff |
| Out of Season | #b2b2b2 |
| Water | #0070fd |
| Other Landcover | #828282 |
| Value | Map Hex Color |
|---|---|
| 0 - 6 | #ff00a0 |
| 6 - 12 | #f00050 |
| 12 - 24 | #ff7878 |
| 24 - 36 | #ffaa00 |
| 36 - 48 | #ff5 |
| Value | Map Hex Color |
|---|---|
| 48 - 60 | #5f5 |
| 60 - 72 | #0a0 |
| 72 - 84 | #55f |
| 84 - 100 | #00a |
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: a weekly depiction of vegetation stress across the contiguous United States.
NOAA Center for Satellite Applications and Research (STAR) normalized difference vegetation index (NDVI) maps
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
A selection of worldwide maps monitoring different aspects of vegetation health.
Global and Regional Vegetation Health (VH) is a NOAA/NESDIS system estimating vegetation health, moisture condition, thermal condition and their products.
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.
Vegetation Research and 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