GeoNodeFeatureCatalogue
Generic Feature Catalogue
Generic Feature Catalogue
1.0
2016-01-11
DataMapWales
pointOfContact
geonode:tow_wales
<p>The Trees Outside Woodland (TOW) for Wales dataset comprises polygon features representing tree canopy cover located outside the National Forest Inventory (NFI) woodland extent. Included features have a minimum tree canopy top above 3m in height and more than 5m2 in area. Canopy extent is then measured down to 1.3m above the ground. There may be areas of contiguous tree canopy greater than 0.5 hectares within this TOW dataset if they do not meet all parameters for inclusion to the NFI. However, for areas of woodland more than 0.5 hectares the NFI should be used.</p>
<p>Canopy polygons were generated from continuous patches extracted from Canopy Height Models (CHM) derived from the Wales LiDAR Survey. Each polygon includes calculated area attributes, a classified woodland type, and associated height metrics. Canopy polygons are further subdivided into defined height-class polygons. This data was created by the Forest Research ‘Remote Sensing Team’, in February 2026.</p>
<p><strong>To note: To maximise drawing performance, the data is only visible when zoomed to 1:100,000 or closer. </strong></p>
<p>Woodland type classifications are derived using a rule-based spatial algorithm that evaluates:</p>
<ul>
<li>The number of individual treetops detected within each canopy polygon;</li>
<li>The polygon area; and</li>
<li>Polygon geometry (e.g., roundness).</li>
</ul>
<p>These parameters are used to assign each feature to one of four woodland type classes:</p>
<ul>
<li>Lone Trees – Single trees, shown as small, separate canopy areas with usually one treetop within them.</li>
<li>Groups of Trees – Small clusters of trees growing close together within the same canopy patch.</li>
<li>Small Woodlands – Larger, continuous tree areas that meet a minimum size or number of trees.</li>
<li>Overhanging Canopy (NFI OHC) – Tree areas that hang over or are next to National Forest Inventory woodland.</li>
</ul>
<p><em><u>Height Classes</u></em></p>
<p>Canopy polygons are stratified into height classes based on derived canopy height metrics. The defined height bins are:</p>
<ol>
<li>Class 3: 1.3 m – <10 m</li>
<li>Class 10: 10 m – <15 m</li>
<li>Class 15: 15 m – <20 m</li>
<li>Class 20: 20 m – <30 m</li>
<li>Class 30: ≥30 m</li>
</ol>
<p>These classes enable structured analysis of canopy structure and vertical distribution.</p>
false
Trees Outside of Woodlands
tow_id
1
1
xsd:string
tow_area
1
1
xsd:int
woodland_type
1
1
xsd:string
height_class
1
1
xsd:double
bin_area
1
1
xsd:int
min_height
1
1
xsd:double
max_height
1
1
xsd:double
mean_height
1
1
xsd:double
stdv_height
1
1
xsd:double
sub_id
1
1
xsd:int
lidar_year
1
1
xsd:string
lidar_date
1
1
xsd:string
british_gr
1
1
xsd:string
type_and_height
1
1
xsd:string
math_o_goedwig
1
1
xsd:string
geom
1
1
gml:MultiPolygonPropertyType