Tree Density estimates the number of trees per hectare (TPH) in a study area based on land cover classification. It is a direct indicator of tree cover, forest structure, and habitat naturalness — higher values indicate denser vegetation and richer ecosystem services.
The KPI integrates land cover data with average TPH values assigned to each CORINE Land Cover (CLC) class, enabling a scalable estimate of tree biomass even without direct field surveys. A high tree density is associated with fundamental ecosystem services: carbon sequestration, hydrological cycle regulation, urban heat island reduction, faunal and floral biodiversity support, soil erosion prevention, and air quality improvement.
According to Crowther et al. (2015), the Earth hosts approximately 3.04 trillion trees, with an estimated net loss of 15 billion trees per year due to deforestation and urban expansion. Monitoring local tree density is therefore a key diagnostic tool for assessing land health and biodiversity risk.
| Level | Range (trees/ha) | Ecological interpretation |
|---|---|---|
| A (Excellent) | > 600 | Dense forest; maximum canopy cover and ecosystem services |
| B (Good) | 300–600 | Well-forested area; mixed or agroforestry land |
| C (Moderate) | 150–300 | Moderate cover; agro-forestry landscape |
| D (Poor) | 50–150 | Sparse tree cover; agricultural or peri-urban land |
| E (Critical) | 0–50 | Very few trees; urban or bare land |
The KPI requires prior generation of the Land Cover layer for the study area. For each land cover class, a mean TPH (trees per hectare) value is assumed based on the CLC class reference table:
| Land Cover Type | Example CLC Classes | Estimated TPH |
|---|---|---|
| Dense forest | Broadleaf forest, coniferous forest | 500 |
| Open forest / Scrubland | Transitional woodland vegetation | 150 |
| Agroforestry | Complex cultivation patterns | 50 |
| Agriculture | Arable land, vineyards, olive groves | 10 |
| Urban / Artificial | Urban fabric, industrial areas | 5 |
| Other (water, bare rock, etc.) | Water bodies, bare areas | 0 |
The estimated tree density is calculated as the area-weighted average of per-class TPH values:
where Area_i = area of land cover class i (ha), TPH_i = trees per hectare assigned to class i
Data are sourced from ESA WorldCover / CORINE Land Cover (CLC) at 10 m resolution.
Gauge. A semicircular gauge displaying the site's estimated tree density (TPH) as the ROI arc and the control area tree density as the CA arc on a five-segment A–E quality scale.
Purpose: How densely forested is this site compared to the surrounding control area, and what ecological quality grade does it receive?
Description: The chart is titled "Estimated tree density" with a topic badge "E4". Two nested gauge arcs are displayed: Site (ROI) and Control (CA). Each arc spans a semicircle segmented into five colour bands from E (left, 0 /ha) to A (right, 1000 /ha). A needle with colour-filled circle indicates where the value falls on the arc. Above the gauge, a letter grade badge (A–E, colour-coded) shows the site's ecological quality. A signed delta value (Site minus Control, e.g., −78.04 /ha) indicates whether the site has more or fewer trees per hectare than the surrounding landscape. An AI comment button and a download button are also present.
350Tree Density
How it's calculated: The ROI value is the area-weighted average TPH across all CLC land cover classes within the site polygon. The CA value is the identical computation over the control area (the reference landscape surrounding the site). The letter grade is assigned by the official thresholds: A > 600, B 300–600, C 150–300, D 50–150, E 0–50. The delta is site minus control area.
Note: This indicator is not inverted — higher tree density always indicates better ecological conditions.
Legend:
| Level | Range (trees/ha) | Color | Meaning |
|---|---|---|---|
| A | > 600 | ■ #00A67A | Excellent — dense forest, high ecosystem services |
| B | 300–600 | ■ #00DF80 | Good — well-forested, mixed or agroforestry |
| C | 150–300 | ■ #FFD21E | Moderate — agro-forestry, mixed landscape |
| D | 50–150 | ■ #FF8B16 | Poor — sparse cover, agricultural or peri-urban |
| E | 0–50 | ■ #FF367F | Critical — very few trees, urban or bare |
Interpretation example:
If the gauge shows grade E and a site score of 0.0 /ha (Control: 78.0 /ha), it means the site has essentially no tree cover — typical of a dense urban or industrial zone — while the surrounding landscape retains moderate scrubland-level cover. The −78 /ha delta highlights a severe vegetation deficit at the site relative to its context.
Highlights Table Row. A row in the KPI comparison table on the Overview page, showing the site's tree density alongside other key environmental KPIs.
Purpose: How does this site's tree density rank relative to the control area and other monitored sites at a glance?
Description: The Highlights table lists multiple KPIs in rows. The "Tree Density" row displays the latest tree density value (ROI, /ha) with colour-coded grade badge, alongside the control area (CA) value. This enables high-level cross-KPI comparison on a single screen.
How it's calculated: Same formula as the Assessment gauge — area-weighted mean TPH across CLC classes. The displayed grade uses the same A–E thresholds.
Interpretation example:
If the Tree Density row shows 0.0 /ha in red (grade E), it signals that this site has no significant tree cover — a flag for biodiversity intervention and green infrastructure planning.
Assessment Sidebar Row. A row in the Assessment sidebar KPI panel showing the tree density value for the site.
Purpose: What is the current tree density grade in the E4 biodiversity assessment summary?
Description: The Assessment sidebar lists KPI values for rapid grade inspection. The "Trees Density" row shows the site's current tree density in /ha with a colour-coded value. It is positioned in the E4 Biodiversity category group.
How it's calculated: Same area-weighted mean TPH formula. The unit shown is /ha.
Interpretation example:
If the sidebar shows "Trees Density: 0 /ha" in red, the site falls in grade E — no tree cover — which contributes negatively to the overall E4 biodiversity assessment.
Sites Progress Column. A column in the multi-site comparison table showing tree density (ROI / CA) for each monitored site.
Purpose: How do tree density values and grades compare across all monitored sites in a single tabular view?
Description: Each cell shows the site ROI value and the control area CA value side by side. The column is tagged under "assess" and "biodiversity" categories.
How it's calculated: ROI and CA values are the same area-weighted mean TPH computed independently for the site and its control area polygons.
Interpretation example:
If a row shows 0 / 78 for a site, it means the site has 0 trees/ha (urban, grade E) while its control area has 78 trees/ha (grade D, sparse agricultural cover) — a significant green deficit.
Line Chart. A time-series chart showing the annual tree density trend at a site over multiple years.
Purpose: Is tree density at this site increasing, stable, or declining over time?
Description: In the Multi-Year Trends section, "Number of Trees" is a selectable KPI type from the chart dropdown. The chart displays annual tree density values as a line over the available time range. The trend allows detection of deforestation events, reforestation progress, or land use change.
How it's calculated: For each year, the area-weighted mean TPH is computed from the annual land cover layer. The time series reflects changes in land cover class distribution across years.
Interpretation example:
If the line shows a drop from 150 /ha in 2020 to 5 /ha in 2023, it indicates a major land use conversion — likely from scrubland to urban fabric or bare land — within the site polygon.
Detail Card. A card in the "Territorial Metrics" section of the iLovenatura widget-light site detail sidebar, showing tree density with a tree-grid visualization.
Purpose: What is the estimated tree density at this site, and how does it compare to the control area?
Description: The card displays: (1) a pine-tree icon coloured by quality grade; (2) the label "Tree Density" with subtitle "Trees per hectare"; (3) the ROI value in large font coloured by the current quality grade; (4) a delta badge (Site minus Control, signed); (5) a visual grid of 20 pine-tree icons in two rows — filled icons (coloured) represent the proportion of the maximum value filled, and empty icons (grey) represent the unfilled portion; (6) a horizontal progress bar below the grid showing the normalised fill percentage. The card appears in the "Territorial Metrics" section when tree density data is available.
How it's calculated: The displayed ROI value is the area-weighted mean TPH for the site. The fill proportion for the icon grid is computed as the ratio of the site value to the maximum reference value (default 100 /ha). The delta is the site value minus the control area value.
Interpretation example:
If the card shows "42 /ha" with 8 of 20 icons filled in orange (grade D), it means the site has 42 trees/ha — sparse cover consistent with an agricultural or peri-urban area — slightly below the 50 /ha grade D threshold floor.
| Source | Provider | Coverage | Resolution | Period |
|---|---|---|---|---|
| ESA WorldCover / CORINE Land Cover (CLC) | ESA / EEA | Global (Europe) | 10 m | 2020–2021 |
The KPI requires prior generation of the Land Cover layer for the study area. The land cover raster is classified into CLC classes, and each class is assigned an empirical mean TPH value from the reference table (ranging from 0 for water bodies and bare areas to 500 for dense forests).
The tree density for the site polygon (ROI) is computed as the area-weighted average of per-class TPH values across all CLC classes intersecting the polygon. The same computation is performed independently over the control area (CA) polygon. The total estimated tree count is obtained by multiplying the mean TPH by the total area in hectares.
Quality grading follows a five-level A–E scale based on the computed TPH value: A (> 600), B (300–600), C (150–300), D (50–150), E (0–50). The delta value is the difference between the site and control area TPH.
The land cover layer is versioned and tied to the ESA WorldCover data release used for the site. A new version is generated on demand when updated land cover data becomes available.