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  • Writer's pictureSim Elliott

The Mens Nature Reserve, West Sussex: Trees, Landscape, Bryophytes, Lichens and Fungi. 20.02.23

Updated: Feb 27

The Mens is an extraordinary landscape; it is a nature reserve maintained by the Sussex Wildlife Trust. The unusual name ... comes from the Anglo-Saxon word ‘ge-mænnes’, meaning common land The Mens | Sussex Wildlife Trust. I had wanted to visit The Mens for a long time, but it is not an easy place to get to by public transport. The nearest public transport stops are train or bus to Billingshurst, but Billingshurst is 5 miles form the Mens; or Petworth, but Petworth is four miles from the Mens; so this is one of the rare occasions where I visited somewhere in Sussex by car; being given a lift by a friend and fellow naturalist.

All sections of text in italics are quotations, sources given.

Bryophytes and lichens are not easy to identify to species level; all identifications in this post are best match identifications; some of the identifications may be wrong! I am only an amateur naturalist; my enthusiasm is greater than my knowledge. The species in this post are things which I noticed and; there are inevitably many things in the Mens which I didn't notice.

Map from themenswebmap1.pdf (

The Mens is very easy to get lost in; and we did. Fortunately I have the OS App with GPS, so was able to located my self with this; although connection to the GPS was intermittent. I would recommend taking an OS map with you.

The Mens is in the low weald, and its landscape is incised by a couple of ghylls; the geomorphology and microclimate of the wood is extremely hospitable to bryophytes. Moreover, the presence of may fallen trees is propitious for xylophagous (wood digesting) fungi. February is not the optimal time for seeing the fruiting bodies of fungi, but we saw some interesting things. On this trip I focussed my observations on fungi and bryophytes; I noted a few lichens, but closer examination of the trees would probably have resulted in observing a greater range of epithetic lichens than I saw.

It certainly has an untamed, mysterious feeling to it and many people describe it as ‘wild’. A long and varied history of management has seen the reserve move from an open, wood pasture system with huge, spreading parkland trees and pollards to a high forest with closely spaced trees with narrow crowns. A lack of management in recent years has added to this silvicultural diversity. ... there are old tracks and banks separating woodland compartments and heavily incised streams full of bryophytes that fracture and divide the site – old fallen giants are found everywhere, many of these brought down by the Great Storm of 1987 and now home to important populations of saproxylic inverte­brates, fungi (almost 600 species found so far) and bats. Trees are almost always left as they have fallen and the amazing structure this creates adds to the wild feel.

There are great towering cathedrals of Beech, their high canopy filtering bright green light to the forest floor in the spring sunshine. Elsewhere Oaks of many different shapes and sizes form a more intimate atmosphere with typical ancient woodland trees such as Wild Service, Midland Hawthorn and Spindle. There are many ancient woodland indicator species such as Yellow Archangel, Violet Helleborine and Opposite-leaved Golden-saxifrage but you have to search hard amongst the fallen and collapsing trees and recent growth of Holly to find them. ... We have always maintained a policy of non-intervention in the main woodlands and continue to monitor changes in tree growth and development, species diversity, succession and the extent of deadwood. Reserve profile | Sussex Wildlife Trust

Geology, geomorphology and ghyll woods

The Mens could be characterised as low weald ghyll wood; ghyll woods are characteristic of the high weald, and whilst the valleys of the ghylls in the Mens are not as steep as the high weald, the abundance of bryophytes is typical of ghyll woods. The geomorphological characteristics off weald woods is caused by the sandstones and clays of the weald outcrops. The softness of the clays, the gradient of the slopes and the abundance of precipitation result in narrow ghylls which often cut in deeply to the clay, which are a particularly propitious environment for liverworts

Map of the Geology of Sussex

(PDF) Ghyll Woodlands of the Weald: Characterisation and Conservation (

The dots on this map represent the Ghyll Wood studied in the article quoyed below (it did not include the Mens)

The introduction of Ghyll Woodlands of the Weald: Characterisation and Conservation

Burnside, Niall & Metcalfe, Daniel & Smith, Roger & Waite, Steve. (2006). Ghyll Woodlands of the Weald: Characterisation and Conservation. Biodiversity and Conservation. 15. 1319-1338. 10.1007/s10531-005-3875-5., explains the basic features of ghyll woodlands and why they are important ecologically.

The Weald of southeast England supports woodland valley systems internationally distinct in both their ecology and geomorphology. The ghyll wood-lands, around 1000 in total, are typically linear features occupying deep and narrow valleys cut into the sandy and silty Hastings Beds and the Weald and Wadhurst clays (Woolridge and Goldring 1962). The sheltered valleys occupied by ghyll woodlands buffer temperature fluctuations and maintain high humidity levels resulting in unusually oceanic micro-climatic conditions (Rose1995). Elsewhere in north western Europe, ghyll-like valleys are rare, and thus the concentration of these features in lowland England has international geomorphological and ecological significance (Rose and Patmore 1997).The Weald has retained extensive tracts of a variety of ecologically important woodland types, and notably the central High Weald (HW) is the most wooded natural area in England (Countryside Commission 1994; Rose 1995 ;Reid et al. 1996; Forestry Commission 2001). Spatial and structural analyses suggest that the ghyll woodland systems are an important and significant landscape feature in the Weald and are of high conservation value (Rose 1995;Rose and Patmore 1997; Burnside et al. 2002). Yet, ghyll woodlands have received only scant attention in the past. The international and national ecological significance of these ghyll woodlands is that they support a unique assemblage of cryptogamic plants with both oceanic and sub-oceanic affiliations (Ratcliffe 1968; Hodgetts 1997). The presence of rich liverwort and moss communities suggests that the ghyll woodlands are of considerable age, and are therefore also likely to support a high biodiversity of other species of conservation concern, particularly terrestrial invertebrates, which share similar micro-environmental requirements (Peterken 1993; Rose and Patmore 1997; Woodland Trust 2000). Most can be regarded as ‘ancient woodland’ (sensu Rackham 1980; Peterken 1981; ForestryCommission 2001), and Rose and Patmore (1997) suggest that field investigations may indicate that some fragments could represent actual remnants of prehistoric woodland. Much of south-eastern and southern England underwent preferential exploitation of woodland following a phase of human expansion in the late Neolithic/early Bronze Age (Waller and Marlow 1994). From a land-use per-pective, however, the steep slopes of the ghylls have meant that, for the most part, they have remaining relatively uncultivated and thus wooded. Historically, the Weald area, though difficult to cultivate, benefited from the iron industry with many woods managed (coppiced) for charcoal production and subsequent iron smelting (Brandon 1977; Cleere and Crossley 1985; Sussex Biodiversity Partnership 2000). This provided early conservation of the woodlands, as the resource was managed on a long-term sustainable basis, and may have resulted in many ghylls maintaining ‘old forest type epiphytic lichens and bryophytes’ (Rose and Patmore 1997). The geology and geomorphology of the ghylls is also distinctive. In the sandstone beds of the Weald, ghylls can take the form of narrow rock-walled gorges. Conversely, where rocks are softer, slopes tend to be shallower and the valleys less confined (Rose 1995). The Wealden ghylls differ from similar features in southwest England, as a result of greater continental climatic influences, and the presence of relatively clay-rich soils. Rose and Patmore (1997) report that similar ghyll-like features do occur in other parts of lowland Britain that were not blanketed by glacial drift. Most, however, are shallow with gentler relief and do not exhibit the steep morphology present in the Weald. Many ghyll valleys extend over 1 km in length and, as a result of the complexity of Wealden geology, traverse a number of different geological strata.

This variability in geology and unusual micro-climate has clear implications for ecological diversity, and is considered to influence the high levels of bryophyte diversity observed in ghyll systems (Rose and Patmore1997). (PDF) Ghyll Woodlands of the Weald: Characterisation and Conservation. : [accessed Feb 26 2023].

Trees and landscape.

The water level was low, as there had been little rain over the last few weeks. This photo shows was typical pattern of liverworts grows on the banks. Further up the banks are many mosses, as there are and the bottom of tree trunks and on fallen branches, and ferns.

Moss on trees fallen across another ghyll.

Another ghyll showing the abundance of bryophytes and ferns.

Fallen trees are left, as part of the management plan, which provides a habitat for many mosses and fungi

The ghylls

The photo shores the force of water. The pipes through the brick bridge were insufficient to contain the volume of water in the ghyll, so the water cut a new channel round the bridge

Communities of mosses and bracket fungi are common on fallen branches. Bracket fungi are consist of various species in many related genera of higher fungi (Basidiomycotina) Bracket fungi / RHS Gardening Brackets are the fruiting bodies of wood decay fungi

This beech is covered in the liverwort Metzgeria furcata, Forked Veilwort; it is a common epiphyte on beech tress. Epiphytes are not parasites in that they grow on other plants for physical support; they do not take energy from the tree.


Atrichum undulatum with Hypnum cupressiforme

Conocephalum conicum

Conocephalum conicum and Pellia endiviifolia

Metzgeria furcata

Ulota crispa or U. bruchi

Mnium hornum

Orthotrichum sp.

Thuidium tamariscinum


Ramalina farinacea

Parmotrema perlatum

Lepraria finkii

Phlyctis argena


Probably staining from the mycelium of a Chlorciboria species fungi; it's hyphae make xylindein, a quinone pigment, that stains wood blue-green, so-called "green oak", being a valued commodity in woodworking, especially Tunbridge Ware

Fomitopsis betulina,

Inonotus obliquus

Bjerkandera fumosa

Daedalea quercina

Hymenochaete rubiginosa

Inonotus radiatus

Trametes versicolor

Exidia glandulosa

Auricularia auricula-judae

Bjerkandera adusta

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