Even before the establishment of the protected area, both Baltic German and Latvian naturalists, including Nikolajs Malta [lv], knew that this region had the richest flora of eastern Latvia.

[3] The reserve is located in the transition zone between the Central Vidzeme Upland with its harsh climate and the Lubāna Plain [lv], 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 area of the reserve lies on the Middle Daugava Lowland [lv], however, the nature of the terrain is similar to the nearby Central Vidzeme Upland.

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.

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.

These are large-grained sand, rich in carbonates gravel of fluvio-glacial origin, pebbles with boulders, and less often loams and dusty material.

Charcoal is found in some of the soil sections, an indicator of forest fires and slash-and-burn agriculture that occurred in ancient times.

The grass cover of alders is dominated by common nettle (Urtica dioica), which forms tall and dense thickets.

Instead, the lower layer of vegetation is formed by cranberry bushes with admixtures of Melampyrum pratense and rarely Chimaphila umbellata.

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.

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).

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 this meadow, tall curtains of greater tussock sedge (Carex paniculata) grow alongside Dactylorhiza russowii and Ligularia sibirica, the reserve containing Latvia's largest population of the latter species.

In transitional bogs, blueberries (Cyanococcus), cranberries (Vaccinium oxycoccos), and marsh Labrador tea[8] join these plants.

In some places in the swamps, there are thickets formed by different species of willow, common alder and rarely shrubby birch (Betula humilis).

[4] The flora of the reserve includes helophytes, plants that grow submerged in water, and species that float freely on the surface.

Among the common aquatic plants are marsh cinquefoil, slender tufted-sedge (Carex acuta), Calla palustris (Calla), buckbean, and marsh fern (Thelypteris palustris), and on some lakes common reeds, saw grass (Cladium), broadleaf cattail (Typha latifolia) and narrowleaf cattail (Typha angustifolia).

Of these, of particular rarity are the swamp sawgrass (Cladium mariscus) and small pasque flower (Pulsatilla pratensis), found in only two places.

Species such as Gladiolus imbricatus, Ligularia sibirica, blue cowslip (Pulmonaria angustifolia), and yellow foxglove (Digitalis grandiflora) do not appear at all in other reserves of Latvia.

For example, only in coniferous forests it is possible to observe spotted nutcracker (Nucifraga caryocatactes), crested tit (Lophophanes cristatus), red-breasted flycatcher (Ficedula parva), goldcrest (Regulus regulus), dunnock (Prunella modularis), song thrush (Turdus philomelos) and redwing (Turdus iliacus), yellowhammer (Emberiza citrinella), etc.

The owners of deciduous forests are garden warbler (Sylvia borin), spotted flycatcher (Muscicapa striata), common linnet (Linaria cannabina).

Among the grasses arrange their nests Eurasian skylark (Alauda arvensis), whinchat (Saxicola rubetra), meadow pipit (Anthus pratensis), northern wheatear (Oenanthe oenanthe), northern lapwing (Vanellus vanellus), western yellow wagtail (Motacilla flava) and white wagtail (Motacilla alba).

But if the first two species in the reserve feel good, nest annually and even to some extent dominate in winter, the gray partridge suffers from the use of fertilizers and pesticides in the surrounding fields.

The grey heron (Ardea cinerea) and black stork (Ciconia nigra) regularly come here for feeding, although the latter species is quite rare.

[9] Of the five species of reptiles, Krustkalni has the largest population of viviparous lizard (Zootoca vivipara), as well as many common European vipers (Vipera berus).

[9] The most numerous species of fish in protected lakes are predators, including the European perch (Perca fluviatilis) and northern pike (Esox lucius).

[9] Based on the results of these studies, it was decided to grant this area the status of a reserve in order to preserve unique habitats and their inherent diversity of plants.

There is a strict protection regime on the territory of the reserve, which prohibits any economic activity: felling of trees, mining, hunting, harvesting of vegetable raw materials, introduced species, etc.