The Vegetation Trajectory Analysis report is designed to help you understand how your rehabilitation site is recovering over time. Rather than looking at your site as a single "snapshot" in time, this analysis shows you the patterns and trends in vegetation growth and stability.
Key principles behind this report
Before diving into specific sections, it's important to understand the philosophy behind this analysis:
Good rehabilitation is not about perfection—it's about progress and resilience.
Your rehabilitated area doesn't need to look identical to surrounding undisturbed landscapes. Instead, what matters is whether:
Your site is becoming more stable over time
Vegetation is responding to seasons in predictable ways (like it should)
Your site is recovering well after stress events (like droughts)
Your site's behavior is increasingly similar to nearby reference areas (analogue sites)
Data source and quality information
Where do the data come from?
All vegetation information in this report is derived from Sentinel-2 satellite data, which is freely available from the European Space Agency (ESA). Sentinel-2 captures high-resolution images of Earth's surface every five days.
Data quality filters
To ensure the data are reliable, we apply strict quality checks:
Cloud Cover Threshold: We only use satellite images with less than 50% cloud cover over your site. This ensures we're looking at clear, unobstructed views of the ground.
Valid Pixel Requirement: The area of interest must have at least 20% valid pixels in each image. This means that at least one-fifth of the image area must have reliable data (not water, permanent shadow, or other obstructions).
What This Means for You: The number of data points available varies from month to month and year to year. During wet seasons, when clouds are frequent, there may be fewer usable images. Similarly, if parts of your site are obscured by water or shadows, you'll have fewer valid data points. This is normal and doesn't indicate a problem with your data.
Current metrics
At the top of your report, you'll see the key metrics that summarise your site's current condition (year to date) based on satellite observations.
These focus on two aspects - vegetation vigour (measured with NDVI) and vegetation moisture (measured with NDMI).
As an example you will see an interactive chart with the percentages and areas of your site that are declining, stable, and improving - both for NDVI and NDMI). Hover over these charts in your report for more information.
Next to your donut chart you will see a percentage value that indicates the amount of area across your entire site that meets the target range. This is calculated based on comparing the year to date median NDVI or NDMI value against the target you have specified.
Note that this value can be skewed by the time of year and the number of observations that have been made when the report has been run.
What is NDVI?
NDVI measures how much green vegetation is visible from satellite imagery. It compares the brightness of red and near-infrared light reflected by plants to calculate a single number that represents vegetation density, biomass, or vigour.
The number: A value between -1 and 1, where:
Negative values often indicate water
0 = bare ground
1 = extremely dense, healthy vegetation
Typical ranges by ecosystem:
Desert/bare ground: 0.0–0.2
Sparse grassland: 0.2–0.4
Healthy grassland: 0.4–0.6
Shrubland: 0.5–0.7
Woodland/forest: 0.6–0.8+
What it indicates: NDVI indicates whether vegetation is healthy, stressed, or absent. Higher values mean denser, more vigorous vegetation; lower values suggest sparse cover or stressed plants.
Your target value: This depends on your ecosystem type and climate. If this is not defined, we apply a default value.
What is NDMI?
NDMI measures water content in vegetation by comparing near-infrared and short-wave infrared light reflected by plants. It indicates whether vegetation is adequately hydrated or under water stress.
The number: A value typically between -1 and 1, indicating how much water is stored in vegetation
Typical ranges by ecosystem:
Desert/dry grassland: 0.0–0.3
Semi-arid grassland: 0.3–0.5
Arid woodland: 0.4–0.6
Healthy grassland: 0.5–0.7
Riparian/wet areas: 0.6–0.8
What it indicates: NDMI shows whether plants have access to water. Higher (less negative) values indicate well-watered vegetation; lower (more negative) values suggest drought stress or moisture limitation.
Your target value: This depends on your ecosystem type and climate. If this is not defined, we apply a default value.
Compliance timeline
Below your graphs you'll have an indication of the timeline from the date when the observations commenced through to your target, with an indication of when the report was generated. You'll also see what target source for reference was selected, whether that was an analogue site, a target land use, or a default.
The number of satellite image scenes over the analysis time period is also listed. We exclude images based on cloud cover and quality metrics.
Why it matters:
More scenes = more complete picture of your site's behavior
Fewer scenes in specific periods = likely due to cloud cover (normal)
Consistent analysis across years makes comparisons valid
What to expect:
Good years (clear seasons): 30–40+ scenes per year
Cloudy regions: Fewer scenes in monsoon/wet seasons
Total accumulation over years builds a robust picture
What to do: Use this as a confidence indicator. If you see very few scenes in a specific period, it's likely due to cloud cover, not data problems.
Zone by zone map + table
This section helps you review each rehabilitation zone in detail. The map and table are linked, so you can click a zone on either one to highlight the same area in both views.
Map: shows where each zone sits spatially and its current condition context. The colours of the polygons within your area of interest are related to their status as per the table (see more detail below).
Table: shows per-zone area, combined NDVI x NDMI score, combined slope/year, 5-year projection, and improving/declining pixel percentages.
Interaction: click a table row to zoom/highlight that zone on the map; click a polygon to highlight its table row; click away to clear selection.
Sorting: click any column header to sort and compare zones quickly.
How status is calculated
Status is based on NDVI and NDMI trend behavior
Declining: more than 30% of zone pixels are classified as declining.
At risk: if either NDVI or NDMI has a negative slope and a projected target breach within 5 years.
On track: neither declining nor at-risk conditions are triggered.
Because status uses multiple signals, a zone can have a negative combined slope and still be 'On track', or a positive combined slope and still be 'Declining' if too many pixels are deteriorating.
Priority sites
Depending on the version of the report that you received, you may also see five priority sites indicated on that map.
If you have those priority sites, those are the ones that the data have indicated need the most attention in the first instance. You can also click on each of those and get the Google Maps link to those sites.
Vegetation trajectory versus target
These two side-by-side interactive charts show how your site's vegetation is tracking against your rehabilitation targets over time, and whether projections suggest you'll meet those targets by 2030 (or your target date).
If you have specified an analogue site, you will see an amber-coloured line and associated data points on your chart. If you have not specified an analogue, you'll see default target ranges based on your land use choice.
The seasonal ups and downs (the wiggle in the lines) are normal - your vegetation should respond to rainfall, temperature, and seasons. What matters is the overall trend direction.
Interactivity
Hover over the graph to get the value of individual points at any time stamp.
Draw a box on the graph to zoom in to a particular time range.
Use the legend labels at the top to toggle series values on or off in the graph.
Return to the default state by clicking the 'home' button within the graph window.
Spatial trend maps
These four maps show where your vegetation and moisture are improving, declining, or stable; as well as where they are currently above target, below target, or borderline. Together, they help you identify problem areas and understand how fast rehabilitation is progressing across different zones.
Known processing errors
Analysis will only work if your polygons cover the majority of at least one Sentinel-2 pixel. This is not a hard and fast rule of the area size, as one polygon could be larger than another but sit at the intersection of pixels. In that case the polygon will not return any data. If no single polygon meets the size criteria, an error will occur.
If you come across other errors, please contact us.