Inland from the narrow lowland belt that encircles Thásos lies a beautiful unspoilt wilderness of mountain ridges, spectacular valleys, ancient pine forests and limestone pavements. It is a truly magnificent landscape of great variety and awe-inspiring views.
Topographically the island's interior is aligned along a series of south-west to north-east ridges, culminating in the spectacular northern rim of Ipsarion Oros towering above Potamia, Panagia and Thassos Town. The summit of the island is Ipsarion itself at 1204 metres high but there are several impressive peaks along this ridge, including Profitis Ilias (1110m), Dio Kefales (1030m), and Touba (1132m). At the extremities of the Ipsarion range lie Ai-Matis (809m) above Skala Maries in the south-west and Trikorfo (805m) above Thimonia in the south-east.
The upland habitats consist of a mixture of woodland, scrub, grassland and bare rock communities. Despite recent fires (which mainly affected lowland forests), conifer woodlands dominate over much of the upland landscape. Here the species involved is black pine Pinus nigra ssp. pallasiana, reaching almost to 1200m on Ipsarion, although it is absent from the most exposed and rocky summits. On the highest ground, to the south-west of Profitis Ilias for instance, the pines are ancient and in places resemble the 'granny' pines of the Caledonian forests in the Scottish Highlands. These appear even more remarkable when growing out of the high altitude limestone pavements, although many of these trees are now dead and there is little or no evidence of regeneration. On the north-eastern flanks of Ipsarion is a remnant area of silver fir forest Abies borisii-regis mixed with black pine. This was reportedly burnt in the recent fires but it should still harbour wildlife that is restricted to fir and hence is worthy of examination. Grazing by goats has prevented the development of a understorey in most forest areas and beneath the canopy is usually a mix of bracken and upland grassland. However, Cistus phrygana extends surprisingly high up the mountains, with tree heath Erica manipuliflora the dominant shrub.
The limestone pavements are widespread in the northern uplands, with vast tracts extending between Profitis Ilias and Ipsarion, and there is also reported to be an extensive area of pavement above the mountain village of Theologos in the south. In spring and early summer the pavements are studded with colour, including the beautiful mauve flowers of wild iris Iris suavolens, but from mid summer onwards they are superficially barren apart from the silvery tufts of Inula verbascifolia ssp. aschersoniana and occasional ferns sheltering in the grykes. Clothing the slopes of the Mesonisi valley alongside the main track up to Ipsarion from Maries is another massive area of broken pavement. Here there are abundant spiny cushions of milk vetch Astragalus angustifolius, patches of thyme Thymus sp., and clumps of Inula. Another extensive area of this 'cushion' pavement occurs on Spitoudia, behind the Mountain Refuge. Apart from the track through to Profitis Ilias that bisects it, this pavement is undisturbed and quite beautiful. This seems to be a unique habitat type on the island and worthy of further botanical and entomological investigation.
Where slightly deeper soils permit the development of stands of vegetation in the open there is a mixture of bracken Pteridium aquilinum, grassland and scrub. Bracken stands are ubiquitous but substantial areas of upland pasture appear to be localised and mainly confined to the ridges between summits. Presumably they are very significant botanically but during my visits they have been parched, with few flowers evident other than the splash of colour from the flowers of Crocus pulchellus. These grasslands have an abundance of butterflies, including Queen of Spain fritillary Issoria lathonia, lesser spotted fritillary Melitaea trivia and brown argus Aricia agestis, and numerous grasshoppers. The scrub types are varied, with pockets of plane Platanus orientalis and even alder occurring at surprisingly high altitudes, but hawthorn Crataegus monogyna is most frequent along with prickly juniper Juniperus oxycedrus.
This very superficial account of the broad habitat types occurring in the uplands on Thásos probably omits some important examples and merely reflects my own experiences during the few visits I have made. Now that access is much easier (see Maps) more of the upland landscape has become accessible to visiting naturalists (and holidaymakers) and hence it is likely that many interesting discoveries will be made in the future. I would be extremely pleased to hear of any natural history observations in the Thásos uplands.