Natural Features of Punkaharju Nature Reserve
Punkaharju lies between Puruvesi and Pihlajavesi, two large basins of Lake Saimaa. Puruvesi, one of Finland’s purest lakes, is known for wide stretches of open water, a small number of islands and for abundant catch of fish. The shores of its islands range from near-barren rocks to tempting expanses of sandy beaches. Demanding insects and plants adapted to sun-baked conditions, such as the rare breckland thyme (Thymus serpyllum), thrive on the steep slopes of the esker islands, while in the interior, you may suddenly find yourself in a lime forest.
You have particularly good chances of spotting a Saimaa ringed seal (Pusa hispida saimensis) in Pihlajavesi because the lake lies at the core of its range. Especially in spring, during the shedding of the winter coat, seals spend their days on remote islets. Hidden behind the rugged rocky shores of Pihlajavesi, the varied forest nature in the interior of the islands also includes landscapes shaped by traditional agriculture.
The most important natural features of Punkaharju are a direct result of the Ice Age. The unique shapes of the esker ridge were formed 11 000 years ago as the continental glacier withdrew towards the Bothnian Sea at the end of the Ice Age.
The first vegetation spread to the area as the land came in view from beneath melt-waters. There are still signs today of the early species which spread in the area. The Yellow Oxytropis (Oxytropis campestris) - which can also be blue - blooms generously along the ridge road in May - June. Today the Alpine Milkvetch (Astragalus alpinus) is a typical northern and esker plant. For the most part the area's vegetation consists of species typical of dry forests. These are for example Catsfoot (Antennaria dioica), the Heather (Calluna vulgaris) and the Lingonberry (Vaccinium vitis-idaea).
The area's steep surfaces create varying habitats: the south and west facing slopes glow with heat on hot summer days, whereas the north and east facing slopes maintain a cool and damp microclimate. Indeed demanding esker vegetation which can tolerate high temperatures thrives on the southern slopes. The soil holds water poorly so plants must also be able to tolerate dry conditions. Along-side the driest pine forests there are also small, lush herb-rich forest islets on the lake shores and at the bottom of "suppa" depressions. Demanding species such as the Wonder Violet (Viola mirabilis), the Great-spurred Violet (Viola selkirkii), the Broad-leaved Willowherb (Epilobium montanum) and Ostrich Fern (Matteuccia struthiopteris) grow in these spots.
In this area visitors have the opportunity to see some of the typical species of dry forests. Visitors may encounter the Tree Pipit (Anthus trivialis), the Spotted Flycatcher (Muscicapa striata), the Common Redstart (Phoenicurus phoenicurus) and the Common Cuckoo (Cuculus canorus). On summer nights at twilight visitors can listen to the mysterious humming of the Nubian Nightjar (Caprimulgus europaeus). Also the Black Woodpecker (Dryocopus martius) and the Great Spotted Woodpecker (Dendrocopos major) nest in the area. The Black-throated Diver (Gavia arctica), the Red-necked Grebe (Podiceps griseigena) and the Great Crested Grebe (Podiceps cristatus) thrive in the area's shoreline waters.
Very fortunate visitors may catch a glimpse of a group of Spotted Nutcrackers (Nucifraga caryocatactes) in the research forest's Swiss and Siberian stone pine forest in Laukansaari area. On the Kaarnalahti Bay and Lake Valkialampi shores there are commonly bite marks left by beavers and during quiet evenings hikers may even see an actual beaver (Castor canadensis). Also the muskrat (Ondatra zibethicus) and the fox (Vulpes vulpes) have been seen in the ridge area.
The Kokonharju area of the Punkaharju Nature Reserve has been left in natural state. The oldest part of the forest was protected as early as 1924 and the area was enlarged in 1991. Because no forest management measures or logging have taken place in Kokonharju, its forests have been left to develop towards natural state. Spruces have growth under sturdy pines and the forest will gradually become overgrown. There are unusually tall trees standing in the lush hollow of the old-growth forest, some of them with a height of more than 40 metres.
As in the past, only small-scale ecological management measures will be carried out in Kokonharju in the future. You can familiarise yourself with the secrets of the natural forest on the nature trail going through the area.
The Punkaharju national landscape where lakes gleam between sturdy pines, requires constant management so that it can remain attractive to human eyes.
Punkaharju is known for its pine-dominated esker forest and on the crest of the esker, you feel as if you are walking under an arch of old pines. The forests lining the esker road have been cautiously thinned during the 2010s. As the oldest trees are dying, younger trees get more space to grow and in fact, there are trees of different ages on the slopes of the esker, from small saplings to giants aged about 200 years. Dead trees are left in the nature reserve to provide habitat for species thriving on decaying wood in locations where they do not interfere with movements in the area.
There is a long tradition of forest research in Punkaharju area. The arboretum in which visitors have the chance to see approximately one hundred tree species, brings its own spice to the area. The arboretum is located next to Punkaharju Esker Nature Reserve in Laukansaari area. Trees from corresponding climate zones have been relocated to Finland as a test to see how they will fare here in Finland. Amongst these there are exceptional species such as the Picea abies f. virgata. Studies and follow-up have helped gather new information on forest nature as well as helped in develop new forest cultivation methods. The Natural Resources Institute Finland (luke.fi is the party which answers for these studies.