MARSH FORESTS - The forested areas of moderate climatic zone have extraordinarily rich nature that depends on highly moist soils and periodical flooding. In Poland, great attention is paid to preserving these sites that are so valuable in terms of nature; therefore, many of them have been covered by strict protection as national parks, nature reserves, and the Natura 2000 protected areas. Alder forest is commonly called “forest on clumps” or “forest on water.” It consists of tree stands with the predomination of the black alder sometimes accompanied by the downy birch, ash, or pine. The bird cherry, water elder, and certain willow species form the undergrowth. Ground flora is sparse, nd its species have little space to live. Around the trunks of trees towering above the water table, there are clumps overgrown by marsh vegetation, and water stays between them for a major part of the year or permanently. Particular clumps can be often far away from one another. These inaccessible forests owe their appearance to the specific water regime. The water level fluctuates and depends on the season and the intensity of rainfall. In winter and early spring, it is fairly high, and after the autumn period of rainy weather, it can rise by even as much as several dozen centimetres. Then, when scorching and dry years come, water disappears completely. The spaces between the clumps dry out. The landscape changes beyond recognition. Many plants and animals try to wait out that time in some more favourable places. These specific water relationships have shown particularly sharply in the most recent years when long-term droughts have been fairly frequent. This does not favour the existence of alder forests as the stagnant waters originate almost exclusively from the atmospheric precipitation. Usually, however, the pre-spring alder forest is filled with water. Now, our attention is drawn to colourful inflorescences of the black alder, the queen of the area, moving with the wind. When snow starts to melt in February, and the frosty and bleak winter comes to an end, near streams and small rivers rolling their waters through the backwoods, a symbol of early spring – the common snowdrop – starts to blossom. Its flowers, smelling of honey, provide the first, sweet food to insects which pollinate them. Even though the plant itself has small dimensions – it grows up to the maximum of 30 centimetres – it is very resistant to frost. Owing to the specific structure, its singular flowers can survive temperatures as low as ten Celsius below zero. Similar to the common snowdrop, the daphne, also flowers in very early spring. Its fragrant, pink flowers clearly enliven the post-winter landscape in still leafless grey forest. In Poland, since the 1940s, this species has been strictly protected by law. The daphne is an extremely toxic shrub. It is worth knowing that, for an adult human, it is enough to eat only 10-12 ripe fruits to die. There are only a few types of birds that can eat its fruits without harm, by which they contribute to the spread of the shrub. Soon after the last ice disappears, the common grass frogs begin their mating. They gather in large numbers in shallow, warmer bodies of water. Males compete for females by sounding characteristic grumbling voices. Sometimes, there are jostles and minor clashes between them. Many females usually lay their eggs just at the edge of water. Their spawn has the form of gelatinous spherical curls, sometimes forming great clusters. It minimizes temperature fluctuations and protects future tadpoles from predators. Initially, after hatching, the tadpoles are completely black, and they have well-formed tail fins. Soon they grow three pairs of external gills with which they respire in the first days of life spent exclusively under water. At the end of March and the beginning of April, the female eagle owl lays 2-3 eggs which it carefully and devotedly hatches for more than one month. The nest (here situated on a clump between alder trunks) has a form of shallow hole filled with dry grass, moss, and with twigs. In time, it also fills with pellets as well as fur and feathers of prey. The nesting period usually lasts three months, during that time, the eagle owls, in their very secretive life, are extraordinarily sensitive to any disturbances. In Poland, this largest owl of the world is covered by strict species protection, and its breeding grounds are declared protected zones throughout the year. Owing to these measures, a slow increase in the numbers of eagle owls is recorded. A very rich life develops on clumps. Many species are also found in other types of forests. They are often accompanied by shrubs such as the bird cherry and black currant. Between the clumps in small depressions filled with water, bog plants grow, such as the spectacular marsh-marigold. Its flowers entice with nectar and a specific arrangement of spots and lines visible only to insects. Inaccessible old alder forest is the right site for the nesting of cranes. The suitably high level of water and boggy bottom are ideal conditions for breeding. The nest is built from rotting and dry parts of plants, and it is surrounded by water which gives relative safety to the brooding birds and their future offspring. Throughout brooding, the crane carefully and delicately turns the eggs with its beak. This action prevents the embryo from attaching to the shell, and the embryo inside the egg grows and develops correctly. While one of the parents sits on the eggs, the other rests nearby, attentively monitoring the surroundings. A foraging roe deer buck wandered near the nest. A pair of eyes carefully watches it from the shrubs. The male crane is somewhat unnerved by this unexpected intrusion. The buck, unaware of being watched, calmly struts ahead. Suddenly, it hears a disturbing rattle and raises its head carefully checking the area. The crane makes several steps in its direction. The buck cannot stand the tension and springs away. After a while, however, it returns and walks around the bird looking at it with an evident interest. Such situations, where a close encounter between different species takes place are fairly frequent in the animal world, although uncommon to the observer. Preserving sufficient water resources is assisted by the activities of beavers. These largest European rodents were threatened with extinction even as late as in the second half of the last century. However, due to multiyear strict species protection, they can be found almost everywhere today. Whenever there is some water and trees to be gnawed, the beavers have been successfully restored into the environment. The damming up of water by this animal constructor creates the extremely beneficial conditions for the occurrence of biological diversity in our forests. The cranes are among those who particularly benefited from it. One pair set its nest in just such a place. In a loud clangour audible over several kilometres, they announce their dominion over this territory. Similar living conditions are suitable to the green sandpiper. This member of the sandpiper family also lives in wooded marshes. The cranes tolerate the presence of a sandpiper, but a beaver swimming nearby is regarded as an intruder. The female leaves the nest to challenge the uninvited guest. Standing up in the protection of its nest, the bird showed great determination, as the beaver is not an easy adversary. The body weight of an adult individual can reach even as much as 29 kilograms with a body length up to 110 centimetres. Beavers are strongly territorial animals and can adapt the environment where they live to their own needs. The telltale signs of their presence are dams and beaver lodges. The dams allow them to widen the areas of their activities, and to secure the access to new feeding grounds. The dams can be used for a number of years. With time, some of these provide the ground for the development of new plants and later, trees. During the progressive transformation of the natural environment, there are frequent conflicts between humans and beavers, even more so presently, since these animals can be increasingly encountered near human settlements. As far as the activities of humans are not always beneficial to the nature, the activities of beavers can return the water regime to a beneficial state, increase the biological diversity, and speed up the auto-purification of waters. Since early youth, the beavers attach great attention to the care of fur. It must be kept in perfect condition to perform its insulation function during the long stay in water. The beavers are very skilful in diving and can stay underwater for more than ten minutes. The young can swim almost instantly after birth but begin diving only in the second or third week of life. During long-lasting droughts, the beaver ponds constitute refugia for many aquatic organisms. The great grey owl is extraordinarily rare in Poland. In 2010, the first ever breeding in our country of this owl was found in the Polesie Lubelskie region. The brooding is an exclusive task for the female, while the male hunts and guards the territory from the chosen vantage point. Its prey consists mostly of small rodents and birds. The great grey owl lives in the vast expanses of pine and spruce forests with admixtures of other coniferous and deciduous trees. However, open spaces, such as glades or meadows, where it is easier to hunt prey, must be nearby. In a waterlogged alder forest, a pair of cranes survives to have young. Still helpless nestlings require a lot of care from their parents. Mallards staying nearby, stir up irritation among the parents. The male decides to chase them away. Quiet and safety around the nest are now most important. The mallards, however, did not fly away from the flood waters, and indulge in a short nap in a certain distance from the nest. While the less experienced male tries clumsily to warm up one of the nestlings, the other chick, led by the mother, receives its first lessons on how to find food. To teach their young, the adult birds have to exercise the utmost patience. There is also some animation in another nest built near the trunk of immersed pine. The cranes stay nearby, keeping a close eye on the nestlings. During this time, the young are particularly vulnerable to attacks from predators, only waiting for opportunity to snatch them. Water surrounding the nest gives it relatively good protection, while the adult birds staying in the neighbourhood can be fairly effective in fending off an attack. The nestlings left alone in the nest will occasionally fight one another. Such squabbles between the young do not happen very often, but they can cause serious wounds in the weaker nestling. Fortunately, a parent appears in time to pacify the troublesome nestling by putting a tasty titbit under its beak. Each parent cares for one young, feeding it with snails, insects, and worms. June. Warm days have encouraged a young great grey owl to leave the nest. It has seated itself on top of a broken pine trunk and keenly monitors the surroundings, just like adult birds do. It doesn’t seem to bat an eyelid at the swarming clouds of insects nearby. Meanwhile, the parents are busy hunting for food, which largely consists of small rodents. The diet may also include birds, amphibians, reptiles, and even insects. Owls typically hunt from a hiding place, diving onto their prey from a branch, pole, or another high vantage point. The young have a hearty appetite during this period, so parents do their fair share of work to fill their hungry stomachs. The grown chicks, up to five in one brood, leave the nest after 3 to 4 weeks. Although unable to fly yet, they are excellent climbers and remain patient while waiting for their parents to bring a tasty morsel from a hunt. The perfect places to stay for the great grey owl are quagmires or open spaces overgrown with hare's-tail cottongrass. Hare’s tail cottongrass grows in peat-forming wetlands and raised peat bogs. It requires wet areas with strong light exposure and plays an important role in the restoration of habitats in former peat extraction sites. It is one of the first species to colonise devegetated areas. The blankets of fruiting hare’s tail cottongrass are a particularly eye-pleasing aspect of bog coniferous forests. The recently common water shortages have a very negative impact on other wetland residents. This includes turtles, which are very rare and hard to spot because of their timidity. The European pond turtle spends most of its life in water. As an excellent swimmer and diver, it can stay underwater for up to one hour when hunting. Like all reptiles, turtles are ectothermic, that is, their body temperature largely depends on the ambient temperature. That is why turtles, whenever left undisturbed on a bright day, climb the surrounding tussocks to warm themselves in the sun. The warming speeds up their metabolism which has been slowed down by a long immersion in cold water. Birch swamp forests grow in northern and eastern Poland, in hollow areas with high groundwater levels. These almost purely birch forests, with clear dominance of downy birches, create an amazing landscape. The impression is made even stronger by the floating scent from the endless carpets of marsh Labrador tea, covered in beautiful flowers this time of the year. Depending on soil moisture, vegetation in the herb and undergrowth layers is particularly diverse here, taking a shrublet-like form in dryer sites, which also is a result of bog bilberries. Trees provide shelter for numerous animals. A spotted eagle has built its nest on one of the tall birches, and it is a bird that is extremely rare in Poland. In this species, only one of the chicks survives as the older eaglet competes with the younger one for food and eventually kills it. The second chick can only make it if the older egg does not hatch. Ornithologists call this behaviour siblicide. Boreal spruce forests on peat, growing inside kettle holes, are a rare habitat limited to a narrow range in north-eastern Poland. Their dominant species is spruce, which causes heavy shading of the ground, hence a very scanty herb layer. However, the shading benefits the growth of mosses. A characteristic rusty-coloured deposit on the bottom of a stream flowing across this area is produced by iron bacteria that draw life energy from the oxidation of iron dissolved in water. Spruce forests are eagerly inhabited by the smallest of our owls – the Eurasian pygmy owl. Bog coniferous forests are a habitat specific to endorheic basins. Pines dominate the tree stand, accompanied by downy birches or spruces The herb layer includes shrublets, mainly marsh Labrador tea and bog bilberry, with scarcer bog-myrtle. This place is beloved by another of our owls – the boreal owl. Bog coniferous forests are unique sites; in Poland they cover only 1% of all forest areas. In an inaccessible place surrounded by bogs, on a tall pine tree, a sparrow hawk watches over its five children. Such remote and tranquil sites are a favourable nesting environment for most raptors. Along a small creek meandering through the forest lies a very rich woodland habitat known as alder-ash forest, featuring black alder and common ash trees. Alders do not form the characteristic root clumps here, so the vegetation lacks that specific clump structure distinctive of alder forests. As a result of a unique microclimate of a forest river, the herb layer is highly developed. Being surrounded by the forest, the river naturally fills up with branches and collapsed tree trunks, which gives this environment a primeval air. Our largest and most beautiful orchid, Cypripedium, has come into bloom on a protuberance of land. This species is under strict protection and has been entered in the Polish Red Data Book of Plants as threatened by extinction. It flowers from mid-May to mid-July. The flowers, though nectarless, have no problems with pollination. They lure insects inside their bulging labella with a strong and pleasant, vanilla-lemon scent that resembles that of pheromones secreted by Hymenoptera. At the edge of a swamp forest, a herd of koniks is grazing. They look very much like extinct wild horses known as tarpans. Tarpans occurred in the forests of eastern Poland till the end the 17th century. Today, thanks to breeders’ efforts, there are many places where we can find their half-wild descendants. These horses are incredibly resilient and perfectly adapted to harsh conditions. They live in herds ruled by a stallion, which leads a group of several mares and their children. Koniks are very friendly and hardly ever run away by the sight of a human. For their part, they are not aggressive to people. They are calm and their foals curious. These animals have undeniable charm. They often travel in search of waterholes or the shade of a forest, where they can rest a little from pestering horseflies. Woodland communities growing within the range of floodwaters that bring fertile silt during inundation are called riparian forests. They are always connected with flowing waters, from small creeks to major rivers. Large fluctuations of water levels are specific to these sites, ranging from very high water in spring, when large riverside areas are inundated, to almost completely died-up river beds during long droughts. The lowering water reveals the tangled roots of riverbank trees. During high waters, they form labyrinth-like structures that provide shelter for fish and other aquatic organisms. Riparian willow-poplar forests grow in the valleys of major rivers, in places where a flood wave occurs every year. The herb layer includes widespread nettles, and the shrub layer contains spindle trees with their eye-catching pink fruit. In the direct vicinity of water, we can find the exotically-looking simplestem bur-reed. Nutrient-rich lowland rivers create excellent conditions for many species of fish and aquatic plants. It is a natural environment of the white-tailed eagle. A dead fish is a true treat for a young individual. Slightly further from the river channel, in places reached by water once a decade or so, we can find riparian elm-ash forests. These rich forests also abound in other broadleaved tree species. Bog forests and marshy meadows are also the places where wolves can be found. A young male trots through its territory, keenly observing the surroundings. Once in a while it stops to sniff and look around. A mown meadow with bales of hale is not the best place to hide. The wolf is spotted from a distance by a white-tailed eagle, which has found a good vantage point on top of a bale. They look each other in the eye for a moment. Eventually, the curious wolf scares off the bird and checks if there is any prey left. Unfortunately, this time, the eagle was just resting here. The wolf has no other choice but to go on looking around. A host of deer has emerged from the wood. The rut is underway, so a mighty buck is visible among the does. He keeps running to and fro, roars, and holds his herd together. He never stops glancing around in case a competitor appears. Dusk is falling, and another, equally large stag emerges from the woods. A fierce fight ensues. The bucks, their antlers locked together, continue to wrestle vigorously for more than ten minutes. The herd of does watch carefully, standing by the forest line. The newcomer turns out to be stronger, and the former ruler loses its herd, surrenders, and quickly flees the scene. In Poland, wolves live in small groups known as packs, which typically consist of several individuals. The wolf is a territorial animal. In search of food, it can travel immense distances within its territory. It mostly feeds on small animals, but if the conditions and the size of the pack allow it, it also looks for larger hoofed mammals, for which group hunts are used. The common hop has found perfect conditions to develop here. Its flexible stems climb up tree trunks for support reaching up to six metres high. Its female inflorescence resembles cones of coniferous trees and shrubs, and cone is the name commonly used to describe it. In late summer, the wide stretches of wetlands resound with distinctive groaning sounds. It is moose rutting season. At dawn, when the dense fog begins to dissipate, moose can be seen, for example, in the Biebrza Marshes. Such wide wetlands are a kingdom of these largest members of the deer family. This moose cow and its calf are foraging at the edge of a forest. Moose feed throughout the day and night, but they show peak activity early in the morning and at nightfall. They often cover large distances in search of food. Another moose cow foraging nearby has stirred the mother into disquiet. Before winter comes, moose move to higher areas into pine forests, where it is easier for them to find food. In autumn, enormous flocks of cranes gather for overnight rest in remote places in open wetlands. They feel safer when surrounded by their kin. The company includes this year’s juveniles, distinguished by their brown-coloured plumage and their typical squeal, which is quite unlike their parents’ characteristic clanging. Mounting excitement can be sensed among the birds at dawn. It is a short moment before they take off. At last, the flock rises from the ground and departs toward nearby feeding sites. It will return here by nightfall to soundly fall asleep. The cranes will proceed further into the west when temperatures drop dramatically and when it gets increasingly harder for them to find food. Tree-covered areas stretching along small water flows and major rivers form natural wildlife corridors for animals to move around safely. Water also carries other organisms – plant seeds and fungus spores. New areas are colonised and gene exchange occurs between individuals that had been living in separate populations. State Forests also significantly contribute to protecting and providing access to wetland areas, for example, by building footbridges and piers that enable tourists to visit these remote but incredibly fascinating places.
