Suomen Luonto
English summaries 7/2001

Three days of enchantment on Estonia\'s Saarenmaa
By: Alice Karlsson, Antti Halkka
Pages: 4-11

At the end of May, biologists on an expedition from Suomen Luonto magazine and The Finnish Broadcasting Company\'s \"Nature Evening\" landed at Tallinn (Estonia). Going by road towards the island of Saarenmaa, off Estonia\'s west coast, the bus driver, Günther Kangur, demonstrating extreme patience, stopped, reversed, slowed down and waited whenever one of the group spotted an interesting bird, plant or rock.

Saarenmaa has Mediterranean-type illumination, an abundance of herb-rich forest plants, and a calcareous soil. Its habitats include sandy heathlands, herb-rich stands, flower-packed meadows with juniper bushes, and alvars (a type of habitat similar to Sweden\'s Great Alvar, with thin or no soil on limestone). Lovely snowdrop windflowers (which, despite their English name are an anemone, Anemone sylvestris) decorate the road verges. On the second day of our trip we visited the island of Abruka. The speciality of this natural paradise is Estonia\'s largest Central European type herb-rich forest.

Seppo Vuolanto was amazed at the variety and sheer number of birds on Saarenmaa island. At Roomassaari harbour we met seal researchers Mart and Ivar Jüssi, who had just been counting the grey seals on the nearby rocks. Ringed seals may also often be observed on the way to Saarenmaa. There are well over a thousand of them in the Gulf of Riga.

On the way to Loode tammik nature reserve Seppo Vuokko spotted a saw sedge (Cladium mariscus), now confined to just two sites in Finland. Mountain sedge (Carex montana), which has disappeared from Finland altogether, occurs patchily in Loode tammik oak woods.

Kauri Mikkola\'s entomological equipment remained packed in his bag, since this is not the best season for butterflies and moths. However, there were plenty of green-veined whites (Pieris napi) about, as well as a few orange-tips (Anthocharis cardamines), small tortoiseshells (Aglais urticae), peacocks (Inachis io) and Camberwell beauties (Nymphalis antiopa).

We also paid a visit to the Kübassari peninsula, where a lovely herb-rich stand is bordered on its eastern side by a limestone shore. Familiar to tourists on Saarenmaa are the Kaali meteorite crater and the Panga outcrop, where we found fossil cephalopods and corals, among other palaeontological finds. On the return trip, on the Estonian mainland Veikko Neuvonen took us to Kloostri park in the Matsalu nature reserve, where a large colony of herons has sprung up within the space of a decade. By the time we caught the passenger ferry to Helsinki, as a result of keen observation during the whole trip the group had managed to record an impressive 147 species of birds.

Lake Lentua - natural and gull friendly
By: Anne Kärkkäinen
Pages: 16-21

Lake Lentua in Kuhmo is a rare breed of Finnish lake - it has not been regulated. This is the place to go to for a sight of the black- and red-throated divers and the wild forest reindeer. The first wild reindeer came over the eastern border on to the islands on Lake Lentua during the 1950s and nowadays there are over a thousand of them.

Lentua provides an ideal place for observing the annual rhythm and life of a body of water undisturbed by hydroengineering of any kind. In contrast to the situation with regulated lakes, the spring floods lift the ice on to the lake\'s shores. Thus, gulls habitually nesting on the rocky islets have to wait longer for their breeding sites to emerge from under the floodwaters. However, once the islets have dried off, there is no danger of the gulls\' nests being inundated by water as they rear their families. On regulated lakes many nestlings are drowned in their nests owing to the artificial raising of the water level during summer.

The national parks committee in the 1970s proposed Lentua as a national park. Despite this excellent suggestion, no such park has been forthcoming. On the other hand, most of the islands and shores of Lentua, covering 27 square kilometres, have been brought under protection through the shore protection programme and Natura.

When lightning strikes
By: Juha Valste
Pages: 24-27

Ancient Finns believed lightning to be arrows fired by the Supreme Being with which this deity punished and frightened people. Many modern people continue to fear thundery weather and lightning, not without reason. In a thunder cloud moist, warm air flows upwards while cold air flows downwards. Small ice crystals rub against larger snow crystals, producing a continuously growing electrical charge. Finally, the charge is released as a bolt of lightning.

Numerous stories and notions exist about lightning, most of them quite unfounded. Despite common belief, lightning may strike twice in the same spot, while rubber boots are no defence against a powerful flash.

Cars and aircraft are safe because the electricity is conducted through their bodywork, leaving the interior unharmed. A yacht out in the open sea may attract lightning, as may a tall building or even higher ground.

Whenever thunder rumbled, the Ancient Germans believed that the god Thor was riding the clouds in his chariot. Lightning strikes were sparks flying to earth when metal was being forged. In fact, the rumble of thunder is due to the sudden heating up of the lightning channel to tens of thousand degrees Celsius.

Many people struck by lightning survive the ordeal. However, an electric current may stop the heart if lightning strikes at a certain stage in heart muscle activity. Fortunately for timid people, the chance of being hit by lightning is infinitesimally small in Finland, where on average there is one lightning strike per square kilometre per year.

Stark beauty and lush greenery in Finnish lakes
By: Jaana Lahtinen
Pages: 40-45

July is a good time for wading out into the lake shallows, or for making a trip by canoe or boat. At this time of year, aquatic plants are lush and most of them are flowering.

Aquatic plants form an important component of the lake ecosystem. Each year, an amount of biomass equivalent to that of a forest in good condition may be produced. There are approximately 150 water plants in Finland, almost a half of them occurring also in the northernmost regions of the country. These plants tell us a lot about the past and present of a lake. By studying the bottom sediments it is possible to discern the history of a lake for up to thousands of years ago.

Lake plants are divided into life forms according to their growing site in relation to the lake bottom and water surface. It is not always easy to categorise them in this way, however, since their individual life form and morphology vary greatly in different environments. Detached from the bottom, either lying at the surface or just beneath it, there are floating plants, drifters and aquatic mosses. Other plants are completely submerged, even their leaves being underwater. Yet others, reeds for instance, push their aerial shoots up every year quite a way above the surface.

In Finland, studies on water plants go back a long way. Based on the water and shore flora, over a dozen lake types have been recognised. Eutrophic (fertile) lake types like the ones that have become separated off from the Baltic during the post-glacial period, are found on the clay soils of the south and south-west and along the coasts. Reedy and rushy lakes, where the water is cloudy due to suspended clay, also occur in the south. Northernmost Lapland\'s dominant lake type is an oligotrophic (barren) expanse of almost neutral clear water supporting sedge beds. However, there are also exotic clearwater eutrophic and alkaline lakes inhabited by water soldier (Stratiotes aloides). Although most of the country\'s lakes are poor in nutrients Finland\'s aquatic vegetation on the whole is luxuriant.

Almost a tenth of the small lakes are showing signs of eutrophication. In northern Europe, however, the greatest threat to many water bodies is the acidification connected with air pollution. Human impact is apparent in different ways in different kinds of lakes. For example, some clearwater plants have become rare due to cloudy water produced by eutrophication. As industry and large settlements bring their discharges under control, the emphasis shifts to the ordinary person. We can improve the condition of a local lake by, for instance, washing our rugs on dry land and by building a proper cess pit at the summer house.

Teksti: Leigh Plester