NDVI Trend (Greenpulse)

Description

This indicator evaluates the trend of the Normalized Difference Vegetation Index (NDVI) using MODIS satellite data at 250 m resolution. It applies the non-parametric Mann-Kendall trend test (Kendall Tau) to assess whether vegetation vigour has increased, decreased, or remained stable over the past two decades.

Each pixel is assigned a trend value between -1 and +1:

• -1: perfect monotonic decrease (constant annual loss of vegetation vigour).
• 0: neutral trend (no significant change).
• +1: perfect monotonic increase (constant annual gain in vegetation vigour).

Intermediate values indicate partial accumulation (gains) or partial degradation (losses). By mapping these trends, the indicator identifies areas where vegetation is consistently recovering, consistently declining, or stable.

What it measures

• Long-term vegetation dynamics across ecosystems.
• Positive, negative, or neutral trends in NDVI.
• Spatial patterns of ecosystem improvement or degradation.

How to interpret

• Positive values (> 0.01): vegetation vigour is improving.
• Negative values (< -0.01): vegetation vigour is degrading.
• Neutral (-0.01 to 0.01): no significant change detected.

Unit / Scale

NDVI trend index (-1 to +1).
Temporal coverage: 2001–2023.
Spatial resolution: 250 m.
Update frequency: Monthly.

Author / Source

Lemu — based on MODIS NDVI data.
Key source:

• Didan, K. (2021). MODIS/Terra Vegetation Indices 16-Day L3 Global 250m SIN Grid V061. NASA EOSDIS Land Processes Distributed Active Archive Center.

🔗 https://lpdaac.usgs.gov/products/mod13q1v061/

Applications in Atlas

• Detect long-term land degradation or recovery.
• Assess impacts of climate change and human pressures on vegetation.
• Prioritise regions for conservation and restoration.
• Support sustainable land management strategies.