Peat and peat bogs

Peat is one of the largest natural wealth in Latvia.

The richest peat bogs are located in Baltic region, particularly in Latvia. The total area of the bog is 6401 km2 or 9.9% of the country’s territory. Here you can find map of all peat bogs in country.  (blue circles with names of bogs) Peat extracted in Latvia is used worldwide – 95% of Latvian peat is exported and last year export amounted to 176 million euros. • In general, bogs cover 10% of the country’s territory. Peat extraction from all Latvian mires is only 4% and due to favorable climatic conditions in Latvia annual natural growth of peat significantly exceeds the extraction volumes. • There are 63 peat extraction and processing companies operating in Latvia.

How much peat is there in Latvia?

In total, Latvia’s peat deposits contain 1.5 billion tons of peat. In the marshes where peat extraction is taking place as of January 1, 2020, the amount of peat was 145.5 million tons. Total peat resources are not precisely determined, but they could be about 11.3 billion m3 or 1.7 billion tons. Most of this resource is not usable – they are covered by valuable forest stands, they are located under the agricultural land and also in protected areas. Most peat reserves are concentrated in the eastern and central parts of Latvia. From the total area of bogs, 49.3% are low bogs, 41.7% are high and 9% – transitional bogs. 69.7% of all marshes are intact, 15% are drained and used in agriculture, 8.4% are covered with drained forest stands, only 3.9% are used for peat extraction. Approximately one-seventh of the area of untouched mires (75 thousand ha) is protected and designated as reserves and barriers.

Peat formation

Latvia’s temperate climate with more precipitation than evaporation, as well as the gently undulating relief and clayey, weakly permeable sediments in bog depressions are a favorable set of conditions for bog formation processes and development. Today, bog complexes in Latvia are complex dynamic systems that have formed and developed over thousands of years and are still intensively growing horizontally and vertically, significantly influencing the dynamics of landscapes.

The emergence of peat and development

Swamps in Latvia have developed in the negative relief forms of the Earth’s surface, which were mainly formed as a result of the action of the last glaciation glacier and its melting waters. The exception is the coastal areas, where the formation of the relief was significantly influenced by the geological processes caused by the development stages of the Baltic Sea. Swamps in the territory of Latvia were formed by swamping of dry land or overgrowth of shallow water bodies, and their formation is significantly influenced by the terrain. It indirectly affects the vegetation factors and hydrological regime of phytocenoses, especially in the initial stage of the bog. In the territory of Latvia, the oldest bogs were formed at the beginning of the Holocene, about 11,700 years ago, in the lowest areas of the terrain, where there were too humid conditions or shallow water bodies and, when plants died, peat began to form and accumulate. As climatic conditions improved and plant biomass increased, peat accumulation became more intense. As the thickness of the herbaceous peat layer increased, rainfall-fed plants gradually became established, and the low bogs developed into transition bogs, the peat layers of which were then covered by the tall type peat.

About 4,800 years ago, average summer temperatures dropped as the climate changed. The phytocenoses of the bog were dominated by sphagnum and sphagnum mosses, which formed mossy peat when they died. A thick, poorly decomposed moss peat layer rapidly accumulated and intense bog dome formation began in the larger bogs (Figure 1). Under the influence of gravitational forces, there was an uneven, slow sliding of peat, the micro-relief characteristic of the high bog was formed, ridges, bends, cracks appeared – llamas and akachi, which filled with water. 3500-3000 years ago, in the northeastern part of the Kurzeme peninsula, unique interdune swamps, which can only be found in this area, began to form in narrow interdune depressions (vigas), between dune ridges (kangars), as watercourses overgrown. Initially, grass or sedge peat formed in the meadow. Later, when the depression had filled with low-type peat and overgrown the kangar, moss swamp vegetation was established and high-type peat accumulated. Several such interdune bogs joined together to form a large moss bog.

Geological and hydrographic aspects

Moss bogs in the territory of Latvia accumulate a large amount of water, containing 89-96% of water. The bog peat layer in a vertical section is very heterogeneous in terms of peat filtration properties, water flows through the upper or active layer (0.4-0.9 m), where groundwater levels are located for a long time. The bottom of bogs is mainly formed by poorly permeable sediments (moraine, clay, etc.) and water absorption practically does not occur.

Peat is formed in the process of natural decay

It is an incomplete decomposition of bog plants, under over current moisture and incomplete supply of oxygen. High bog peat is made up of herbaceous plants, mainly of different mosses. Approximately 95% of moss’s peat volume and pores. The tiny pores are filled with water, but rough – the air, so the peat roots provide ideal water and air treatment. The age of the peat deposits is 6-12 thousand years, and it turns out that 1 mm of the current peat layer was formed during the year. Peat is formed under anaerobic conditions and is sterile. It is sour, with a low content of nutrients, therefore, adding turbid lime material and composting with organic manure, it is a high-quality material for the formation of humus in the soil.

What is a swamp and a peat deposit?

In order to be called a peat deposit, the peat layer must be at least 30 cm thick at least 2 ha, but more than (or equal to) 1 ha within the depth of industrial use (0.9 m) and the average depth of peat must be greater than (or equal) 1 m, and it is irrelevant whether the peat deposit contains forest or bog habitats. 9600 peat deposits have been identified in Latvia. Of these, 5,100 are larger than 10 ha and more than 1,100 are larger than 100 ha. More than 500 deposits could be used for industrial peat extraction. From the biological point of view, the thickness of the peat layer does not matter to name the place as a bog, the most important is whether the site is dominated by bog vegetation.

Peat Characteristics

Characteristics of the organic layer. Peat stocks, peat structure

As a geological formation, peat is a loose or poorly consolidated organic sediment containing about 50% dry matter minerals and accumulated under conditions of high humidity and oxygen deficiency through incomplete decomposition of dead plant biomass. The moisture content of natural peat is usually 85-96%, depending on the degree of decomposition and type of peat. Ash content generally increases with layer depth, 1-3% in moss peat, 5-15% in low-type peat layers. The exception is degraded bogs, where the amount of ash in the peat can also increase in the upper layer. Peat is a slowly renewable natural resource. Peat is thought to accumulate an average of 1mm per year. However, the results of the latest studies in Latvia prove that the layer of poorly decomposed moss peat accumulates 3-4 mm per year. About 800,000 tons of peat accumulate in natural bogs in Latvia annually. That’s about the same amount produced annually in the 21st century. at the beginning. The detailed researched peat reserves in the bogs, where peat extraction has not yet started, is about 160 million tons.

Type of peat

The oldest in Latvia are the low-type or medicinal bogs. They are characterized by a more intense accumulation of peat in the initial stage of their development, but in the upper layers of the bogs, the intensity of peat accumulation decreases, which indicates significant changes in the hydrological regime of the bog. During the last 2500 years, the climate has become cooler and wetter than during the climatic optimum and there has been a rapid development of moss bogs and an intensive accumulation of poorly decomposed moss peat. Bogs in Latvia usually go through three stages in their development cycle, during which three different types of peat are formed according to the plant composition: mossy (high type) peat, transition type and herbal (low type) peat. Peat is divided according to the degree of decomposition of plant residues: poorly decomposed (<20%), moderately decomposed (20-35%) and well decomposed (>35%). In Latvia, the main peat-forming plants in moss bogs are Magellanic sphagnum (Sphagnum magellanicum), narrow-leaved sphagnum (Sph. angustifolium), brown sphagnum (Sph. Fuscum), common sphagnum (Polytrichum commune), woolly pillow (Eriophorum vaginatum), marsh sphagnum (Scheuchzeria palustris). ) moss (Hypnum) species. About 25 other plant species are <1% present.

Formation of low moor peat

Grass peat in Latvia is formed in low marshy conditions in relief depressions, overgrown water bodies, river floodplains and places where there is a high groundwater level. The main medicinal peat-forming plants: sedges, reeds, sedges, etc. c., which feeds on mineral-rich groundwater, surface runoff and flood waters. Grass bog peat has a high degree of mineralization (6–16%), moderate to high degree of decomposition (25–50% and more), and a characteristic dark color (Figure 2a). Peat acidity is typically pH 5.5-8. In transition type bogs in Latvia, as the thickness of the peat layer increases, plants feed on groundwater and precipitation and the peat becomes more acidic (pH 4.5-5.5). Transition type peat consists of the remains of oligotrophic and eutrophic plants in different degrees of decomposition. The color of the peat is dark gray or brownish (Figure 2b). As the peat layer becomes thicker, ombrotrophic plants dominate and tall type peat accumulates. The development of the high marshes is associated with rapid growth of various sphagnum species, etc. c. the introduction of ombrotrophic peat-forming plants, which feed only on rainwater, into the composition of the bog vegetation, i.e. see brown sphagnum, sheichceria, pillows, Magellanic sphagnum, polyleaf andromeda (Andromeda polifolia) and cypress. High-type peats are formed and accumulate in bog domes during the last stage of bog development, when plants feed only on rainwater. It is therefore the most acidic type of peat (pH 4.5-2.8), very moist (90-96%), with a low degree of decomposition, a yellowish-brown color and clearly visible plant remains.

Latvia – major peat extraction country 

Depending on the amount of precipitation and the number of sunny days, the amount of peat extraction varies during the season. In Latvia, peat is mainly produced for horticultural purposes, and to a very small extent for activated carbon production and other purposes. Mostly peat is used as a substrate. Peat in the Baltic States is in demand worldwide and is used for growing vegetables, herbs, flowers, tree plants and for landscaping. Latvia produces about one third of the peat used in professional gardening in Europe.

Other issues The peat manufacturing industry was the first to introduce collective labour agreements, medical benefits and pension plans.