Garth Wood

Also within

South Glamorgan County

Geology & landscape

Geological Feature: Cave / Cavern, Gorge / Ravine · Geological Period: Carboniferous · Rock Type: Carboniferous Limestone, Limestone

Landscape processes: Fluvial, Karst

Description

Description Garth Wood is of special interest for its semi-natural broadleaved woodland, particularly its stands of beech Fagus sylvatica woodland, growing near the western limit of its natural range. The site is also of special interest for the nationally rare spider Porrhomma rosenhaueri, found within Lesser Garth Cave. The wood is situated 1km west of Tongwynlais, on the outskirts of Cardiff, on the steep western slopes of the Taff Gorge at the southern edge of the South Wales coalfield. The site lies at an altitude of 30 to 175m and most of the woodland has a northerly aspect. Soils are typically free-draining fine loamy or silty, brown earths over Carboniferous Limestone. Garth Wood is dominated by mature beech, with a structurally variable shrub layer, mostly comprising hazel Corylus avellana and hawthorn Crataegus monogyna. The field layer is also variable and often sparse under the dense beech canopy; locally abundant species include bluebell Hyacinthoides non-scripta, wood anemone Anemone nemorosa and ivy Hedera helix. Bird’s-nest orchid Neottia nidus-avis occurs here amongst locally frequent sanicle Sanicula europaea. Garth Wood also supports stands of mixed broadleaved woodland with ash Fraxinus excelsior, sycamore Acer pseudoplatanus and birch Betula pendula. The shrub layer is well developed, including frequent wych elm Ulmus glabra, hazel Corylus avellana and spindle Euonymus europaeus. The field layer includes locally abundant ramsons Allium ursinum and hart’s tongue fern Asplenium scolopendrium, with bluebell, dog’s mercury Mercurialis perennis and ivy. Also present on the site is a small stand of pedunculate oak Quercus robur woodland. Lesser Garth Cave is one of the two known UK locations for the nationally rare troglobitic spider Porrhomma rosenhaueri. Remarks: The site supports woodland vegetation assignable to the habitat types ‘Asperulo-Fagetum beech forests’ and ‘Tilio-Acerion forests of slopes, screes and ravines’ listed on Annex I of the EC Habitats Directive (Directive 92/43/EEC on the Conservation of Natural Habitats and Wild Flora and Fauna).

Species mentioned

Insects to look out for

These moths, butterflies and beetles are known to feed on plants recorded at this site, and carry a notable UK conservation status — but a host-plant being present doesn't mean the insect has actually been recorded here. Treat this as "worth watching for," not a confirmed sighting.

Host-plant data: Cook et al. (2025), Traits data for the butterflies and macro-moths of Great Britain and Ireland, 2024, UK Centre for Ecology & Hydrology / Butterfly Conservation; and Padovani et al. (2020), Database of Insects and their Food Plants (DBIF), UK Centre for Ecology & Hydrology (both Open Government Licence). Contains data supplied by UK Centre for Ecology & Hydrology.