Ecological Structure of the Naliboki Forest
Naliboki Forest is situated on the west of the East-European plain and geomorphologically appears as a vast, flat, low-lying plain (relatively the Naliboki plain), which covers the downhills of the upland. The surface of this plain has a significant slope to the south-west. It consists of the eastern part of the Upper-Nyoman (Verkhnenyomanskaya) lowland (this part is called Naliboki lowland), Lida (Lidskaya) plain, as well as the western part of the Stauptsy (Staupetskaya) plain. On the south-west Naliboki plain is adjoined by the Navagradak (Navagradskaya) upland, on the north-west by the Ashmiany (Ashmianskaya) upland. Local places of the Ashmiany upland to the north-western part of Naliboki Forest and territories of the Mensk upland to the north-eastern part of Naliboki Forest have considerably richer lands, which are based mostly on moraine and contain a bigger part of clay fraction. The rest of Naliboki Forest, its bigger part, situated on the so-called Naliboki flatland, with the exception of the alluvial soil of river valleys, mainly consists of poor land such as sand and fluvia-glacial origin lands or aeolian sand, or peat, which were under the process of covering with over the fluvia-glacial sand layers during the after-ice-age thousands of years. There are great amounts of peat in the lowlands. However, Naliboki flatland contains quite a big number of local places, where the lands are richer, and those lands are moraine with a thin layer of sand, or the mentioned above alluvial ground deposits. Besides that, the important lake-glacial processes in Naliboki flatland resulted in considerable accretion with admixtures of clay fractions.
In the whole Naliboki Forest (i.e. as mean-weighted estimates) forest habitats prevail – 83.3% of the terrain. The forested part mainly consists of the following habitats: mixed coniferous forest older than 60 years – 17.1%; pine plantation with birth overgrown that is younger than 60 years – 18.0%; black alder swamped forest with or without many birches – 19.0%; succession small leaf deciduous forest with or without many spruces that is younger than 60 years – 13.5%. There are no much mixed coniferous forest older 60 than years (2.1%) and spruce forest older than 60 years (5.3%), whereas mostly broad-leaved deciduous forest older than 100 years, i.e. real broad-leaved deciduous oldgrowth survived through the intensive logging during the last two centuries on a very small part of Naliboki Forest only – 0.3%. Nevertheless, in Belarus and other neighboring regions there are actually a few forest massive, where such centuries-old forest fragments still exist, and Naliboki Forest is one of them. In these oldgrowth patches the oldest oak trees, which grow on the distance of 15-60 meters apart, and aged 200-400 years. In the oldest such tree stands the mean oak age constituted 326 years old according to 14 estimates. Succession mostly broad-leaved deciduous forest (but with spruces and small leaf trees) younger than 100 years is more or less common - 2.1% of the terrain. Such forest stands with age of 60-100 years old comprise about 1% of the terrain. There are many recent clearcuts of 5-10 ha that were logged during the last 5 years, and altogether they comprise about 4.2% of the terrain.
As to openings in Naliboki Forest, they are widely spread – 16.7% of the terrain. Despite of the terrain-wide draining that happened in the 1960s-1980s, the openings are mostly not an intensive rural lands, but they stay as either nearly abandoned non-swamped meadows (4.9%) or secondary swamped drained lands mostly in effect of damming of the drainage canals by beavers (0.8%) or open grassy marshes in abandoned peatary (0.3%). Also open grassy marshes and other less or even non-swamped grassy openings in river valleys cover 8.2% of Naliboki Forest, and the water area (rivers, canals, lake Kroman, floodplain lakes, relatively large beaver ponds) constitutes 0.7%. Real agriculture fields cover 1.7% of the terrain only. The grassy openings on the drained lands, which are nowadays mainly out of human use, have a very dense grass stand and therefore they do not overgrow with bushes and trees. These grassy openings look like a strange steppe terrain inside the forest massive. Similar situation is going on with the abandoned peataries, where the places with too acid peat are covered by small sedges and some small birches. These habitats have a strange boreal look that in some places is similar to tundra or forest tundra.
The density of watercourse network (rivers and canals) varies from 1.2 to 2.9 km per one km2, and it averaged 2.1 km/km2, whereas the density of river (with a natural riverbed) network is 0.1-0.5(mean 0.4) km/km2 and one of canalized rivers and various (mostly drainage) canals is 0.7-2.8(mean 1.7) km/km2. In some places, as an effect of draining, there are particularly many canals– 1.6-6.0(4.5) km/km2. Also, it is worthwhile to point out how many kilometres the main watercources flow within Naliboki Forest or at its edge. Our measurements of the stream stretching within Naliboki Forest are as follows: Nyoman big river - 78 km; Biarezina medium-sized river – 84 km; Islach small river – 76 km; Volma small river – 10 km; Vusa small river – 40 km; Volka small river – 59 km; Sula small river – 16 km; Alshanka small river – 16 km; Zhouta-Nyomanski canal – 22 km; Shubina-Nyomanski canal – 19 km.