Krustkalni Nature Reserve () is a nature reserve located in eastern Latvia that was founded in 1977.Reserves of the USSR: in 11 volumes. ed. V. E. Sokolova, E. E. Syroechkovskogo. M .: Mysl, 1989. T. Zapovedniki Pribaltiki i Belorussii. S. 170—173. It has an area of 2,978 hectares. Since 2004, this institution has been part of Natura 2000, a European Union network of protected areas. The reserve is managed by the Latgale regional administration.
The nature reserve was created to preserve the characteristic biodiversity of the complex of water and forest ecosystems, a complex of coniferous forests and meadows, as well as underground springs that form small swamps and lakes. A feature of these springs is high calcium content, due to which limestone soils are formed. They encourage the growth of calciphile plants, which often occur in the coastal areas of the country, but are not typical of eastern Latvia. The reserve has 32 species of plants and 37 species of animals listed in the , and the number of Red Book plants in Krustkalni ranks second among the country's reserves.Reserves of the USSR: in 11 volumes. ed. V. E. Sokolova, E. E. Syroechkovskogo. M .: Mysl, 1989. T. Zapovedniki Pribaltiki i Belorussii. S. 173—179.
History Before its creation, the lands of the reserve belonged to the Krustkalni forest research station. Even before the establishment of the protected area, both Baltic German and Latvian naturalists, including , knew that this region had the richest flora of eastern Latvia. Due to the difficult terrain, these areas were challenging to cultivate and impossible to apply intensive methods of forestry. At the same time, due to the height differences and the variety of landscapes, this area was characterized by rich vegetation and fauna. Given these two factors, From the 1950s, researchers from the University of Latvia and the university's Institute of Biology began to explore the area, and it became a venue for student field internships. Under the leadership of the Institute of Biology, the first nature reserve in eastern Latvia was established there on April 15, 1977.Līga Ozoliņa-Molla, Markuss Molls. National parks and reserves in Latvia. Zvaigzne ABC, 2015. . In total 69 land lots of the forest became a nature reserve, but temporarily remained in use by the research station. In 1979 the Slītere Nature Reserve was established, to which all other Latvian reserves including Krustkalni were subordinated. In 1982 Teiči Nature Reserve was organized, also in eastern Latvia. Since the Teiči reserve was located in the same region as Krustkalni, a joint administration was established for the reserves, subordinated to the Latvian Production Forestry Association "Latvias Mejs". Since February 1, 2011, the joint administration of both eastern Latvian reserves has been under the direction of the Latgale regional administration.
Climate The reserve is located in the transition zone between the Central Vidzeme Upland with its harsh climate and the , which is characterized by warmer continental air. The influence of the coastal climate on its territory is weakened due to the relative separation from the coast of the Baltic Sea and the middle Latvian uplands. The frost-free period, with temperatures above 5 °C, lasts 180 days. The average minimum temperature is -28 °C. 600 mm precipitation falls here annually and is distributed as follows: about 350 mm evaporates, and 250 mm becomes surface runoff. The varied terrain determines the diversity of microclimatic conditions in parts of the reserve.
Geography and hydrology The reserve is located in eastern Latvia, on the border of the Vidzeme and Latgale historical regions. Its territory lies entirely within Madona Municipality, whose center, the city of Madona, is 15 km from the boundaries of the reserve. The outline of the reserve resembles a triangle, which reaches the village of in the northwest, in the northeast is bounded by the Madona–Jēkabpils road, and in the south the Aiviekste river, which flows on the outskirts of Ļaudona village.
The area of the reserve lies on the , however, the nature of the terrain is similar to the nearby Central Vidzeme Upland. During the last ice age, there was significant deposition of glacial material, which formed the Madonsko-Trepsky shaft. Krustalny occupies its narrowest part from Lake Dreimaņa (or Svētes, ) in the north to the Aiviekste River in the south. Within the reserve, the shaft consists of 2–5 ridges, up to 4 km long, with a total width of 1–2 km at 153 m above sea level. Each of the ridges is 70 to 250 m wide, and has a relative height of up to 50 m and a slope of about 35°. Between the ridges are lowlands (well drained or swampy) and wide ravines.
Along the south-eastern slope of the Madonsko-Trepsky shaft stretches the Dooku-Svetes depression, at an elevation of 95–100 m. It is the flat bottom of an ancient lake that existed in the Holocene. A large amount of carbonates were deposited in the lakebed, and for some time lime was mined there industrially. Now on the site of the former quarries some ponds have gradually overgrown and turned into meadows.
There are many bodies of water in the reserve, which can be divided into three types: lakes, rivers and springs. The largest in the area are the lakes, of which there are 13. Among them is Lake Dreimaņa, on the southwestern shore of which is a one and a half kilometer peninsula. Like other lakes concentrated in the eastern part of the protected area, Dreimaņa has marshy shores and a bottom composed of limestone with layers of silt. From the lake the Svetupe River flows through the central part of the Dooku-Svetes depression to the south, absorbs the tributary and flows into the Aiviekste. Another river, the , has a spring supply and encircles the reserve from the southwest. All of these rivers are small and winding, with low banks and rich vegetation. The reserves's springs are concentrated at the foot of the hills and on the shores of Lake Dreimaņa.
Geology and soils The glacial origin of landforms determines the composition of geological rocks. These are large-grained sand, rich in carbonates gravel of fluvio-glacial origin, pebbles with boulders, and less often loams and dusty material. In some places, these materials are covered with boulder loams or sandstones. In the Dooku-Svetes depression, the carbonate rocks began to form in the boreal period and continued to accumulate in the subboreal period, with their deposition ending in the first half of the Atlantic period. The limestones of the depression are floury and fine-grained, with a carbonate content of 8890%. The limestone layer reaches 5 m in thickness, covered with medium-decomposed peat, which varies in thickness from 0.1 to 2.5 m. Thus the Dooku-Svetes depression has the largest deposits of lake limestone in Latvia.
The soils of the reserve are diverse. In the northern part of the protected area podzol soils predominate, in the rest of the territory peaty podzol, and very small areas are occupied by gleysol and rendzina soils. Among peat soils, the types inherent in fens predominate. Charcoal is found in some of the soil sections, an indicator of forest fires and slash-and-burn agriculture that occurred in ancient times.
Flora
The reserve's ecosystem hosts 604 taxa of plants including 23 species of ferns, 12 species of gymnosperms and 569 angiosperms. The flora of the reserve is dominated by members of the families Asteraceae, Poaceae, Cyperaceae, Fabaceae and Rosaceae. The Orchidaceae family is also well represented by 17 species.
According to geobotanical zoning, the reserve belongs to the western sub-province of the East Baltic floristic district, but is located close to the border of the eastern sub-province. This is evident by the mixed nature of its flora, which includes both typically eastern Latvian species (for example, Ligularia sibirica) and species that usually grow much further west on the . Species with Eurasian, European and subarctic habitats make up a significant part of the protected flora.
Forest vegetation The variety of microclimatic conditions and landforms determine a wide range of plant communities and vegetation classifications. The most common plant communities of Krustkalni are pine and spruce forests, which alternate with small-leaved forests, small meadows, overgrown farmland and swamps of various types. The reserve belongs to the Baltic-Belarusian sub-province of the Northern European taiga province of the Eurasian taiga of the Holarctic realm, so the zonal types of forests for it are complex and deciduous spruce. It is these forests that occupy the highest altitude areas, while lower areas are populated with oak forest, aspen and birch, and green mosses (Pleurozium schreberi, Hylocomium splendens and Dicranum polysetum), Pteridium aquilinum, and bilberry (Vaccinium myrtillus). On the slopes of hills, on fertile soils grow spruce forests with Oxalis acetosella cover. Extremely rare are oak forests with green moss cover. In former clearcutting areas, instead of primeval forest, a new forest has formed from grey alder (Alnus incana), and in the undergrowth there are many small-leaved lime (Tilia cordata), hagberry (Prunus padus), rowan (Sorbus aucuparia), and blackcurrant (Ribes nigrum) plants. The grass cover of alders is dominated by common nettle (Urtica dioica), which forms tall and dense thickets. In contrast, the pine forests appear light because they grow on dry sandy soils, which are not suitable for most forest grasses. Instead, the lower layer of vegetation is formed by cranberry bushes with admixtures of Melampyrum pratense and rarely Chimaphila umbellata. On the tops of the hills, this cover changes to a thicket of blueberries or a mixture of cladonia lichens (Cetraria islandica) from Ericaceae.
Forests on carbonate soils have a unique composition. They can be of different types (spruce, aspen, birch, very rarely pine or goat willow), but always contain minor amounts of deciduous species: small-leaved lime, European oak (Quercus robur), Norway maple (Acer platanoides), European white elm (Ulmus laevis) and wych elm (Ulmus glabra). Undergrowth in such forests is very dense and diverse including European fly honeysuckle (Lonicera xylosteum), common hazel (Corylus avellana), guelder rose (Viburnum opulus) and Daphne mezereum. The grass cover of such forests is very similar to the cover of southern oak forests. In particular, it contains a lot of ground elder (Aegopodium podagraria), may lily (Maianthemum bifolium), Anemone hepatica, Dog's mercury (Mercurialis perennis), Asarum europaeum, and sweetscented bedstraw (Galium odoratum).
In the lowest parts of the reserve grow a variety of swampy forests. Birch forests have ground cover formed by sphagnums (peat mosses, mostly Sphagnum magellanicum), marsh Labrador tea (Rhododendron tomentosum) and bilberry; if the forest consists of downy birch (Betula pubescens), then common reed (Phragmites australis), buckbean (Menyanthes), purple moor grass (Molinia caerulea), fibrous tussock-sedge (Carex appropinquata) and Carex cespitosa, and sedges with their turf form a characteristic bumpy microrelief. In spruce forests the grass cover is dominated by ferns and sedges; common alder forests are rich in such herbs as may lily, common nettle, chickweed wintergreen (Lysimachia europaea), ground elder, cabbage thistle (Cirsium oleraceum), and meadow sweet (Filipendula ulmaria). Shrubs are sometimes found in the forests of the reserve which are not very common in Latvia. In dry forests single juniper specimens may be encountered, and on more fertile soils European spindle (Euonymus europaeus) and Euonymus verrucosus.
Meadow vegetation