Tree density estimates the number of trees per hectare (TPH, Trees Per Hectare) in the study area, providing information on tree cover, tree distribution, and the presence of natural and anthropogenic habitats. The indicator combines land cover data with average TPH values defined for each CLC (Corine Land Cover) class, enabling a scalable estimate of tree biomass even in the absence of direct field surveys.
High tree density is associated with fundamental ecosystem services: carbon sequestration, hydrological cycle regulation, urban heat island mitigation, faunal and floral biodiversity support, soil erosion prevention, and air quality improvement. According to Crowther et al. (2015), Earth hosts approximately 3.04 trillion trees, with an estimated net loss of 15 billion trees per year due to deforestation and urban expansion.
This KPI requires the prior generation of the Land Cover map for the study area. For each Land Cover type, an average TPH value is assigned, defined in the clc_class table:
| Land Cover Type | Example CLC Classes | Estimated TPH |
|---|---|---|
| Dense forest | Broadleaf, coniferous forests | 500 TPH |
| Open forest / Scrubland | Transitional woodland | 150 TPH |
| Agroforestry | Complex cultivation patterns | 50 TPH |
| Agriculture | Arable land, vineyards, olive groves | 10 TPH |
| Urban / Artificial | Urban fabric, industrial areas | 5 TPH |
| Other (water, bare rock, etc.) | Water bodies, bare areas | 0 TPH |
Calculation formula:
Estimated trees = Σ (Area_class_i [ha] × TPH_class_i)
Density [TPH] = Total estimated trees / Total hectares of study area
Derived indicators:
trees_density — average tree density per hectare in the study arean_trees — total estimated number of trees in the study area| Code | Name | Provider | Resolution | Availability |
|---|---|---|---|---|
WRD_ESAXX_99 | ESA Land Cover / CLC | ESA / EEA | variable | continuous |
| Indicator | Unit | Range | Inverted |
|---|---|---|---|
trees_density | /ha | [0, 50, 150, 300, 600, 1000] | No |
n_trees | - | [0, 10, 20, 50, 100, 200] | No |
Inverted = No: a higher value indicates greater tree presence and more favourable conditions for biodiversity.
Levels for trees_density (TPH):
| Level | Density (/ha) | Interpretation |
|---|---|---|
| A (Excellent) | > 600 | Dense forest cover; maximum ecosystem services |
| B (Good) | 300 – 600 | Good tree cover; mixed or agroforestry forests |
| C (Moderate) | 150 – 300 | Moderate cover; agro-forestry landscape |
| D (Poor) | 50 – 150 | Low density; predominantly agricultural with few tree elements |
| E (Critical) | 0 – 50 | Near absence of trees; urban, intensive agricultural or bare soil areas |
trees_density
(/ha)n_trees
Tree density per hectare estimation based on land cover classification. Each CLC class has a TPH (Trees Per Hectare) value defined in the clc_class table (e.g.: dense forest = 500 TPH, agriculture = 10 TPH, urban = 5 TPH). Formula: Estimated trees = Σ (Area_class [ha] × TPH_class); Density = estimated trees / total hectares. Requires prior Land Cover generation for the study area. Data source: WRD_ESAXX_99 (ESA/CLC data).