Fen: Presseler Heidewald (outside the nature park area) High moor: Kleiner Kranichsee Nature Preserve
There is a variety of aspects that distinguish moors. They can be roughly categorized into fens, transitional moors, and high moors based on their sources of water. Moors fed by groundwater rich in nutrients are referred to as Fens. High moors, on the other hand, are fed exclusively by precipitation, which is generally low in nutrients and relatively acidic. Transitional moors are a transitional type of moor - with the topmost layer of peat in these moors no longer influenced by groundwater, while the nutrient content and pH value remain considerably higher than in the high moors and the vegetation composition being much richer, although peat mosses may also be present.
An ecological typification of moor areas can be undertaken based on the plant communities, the nutrient content, and the pH value. Moors can be subdivided into hydrogenetic moor types based on the formation history, which must also take into consideration the geological and geomorphological characteristics of a region.
The Ecological Moor Types
The following figure shows how the nutrient content and pH value of water feeding into the moor effect the composition of the vegetation and therefore the entire moor. The moors in the “Erzgebirge/Vogtland (Ore Mountains/Vogt County)” nature park can be categorized as oligotrophic moors, depending on if they are fed exclusively by rainwater or also receive surface water.
Hydrogenetic Moor Types
In addition to the hydrological characteristics (water quality, flow of water into the moor, fluctuations in water levels throughout the year) of the moor bed and its catchment area, the geomorpholgoical (topographical), climatic (temperature, rainfall, evaporation), geological (rocks present) vegetation-related (peat-forming vegetation conditions in the area are factored in when determining the hydrogenetic moor type. Consideration is also given to the history of the moor’s development, the change between warm and warm times, and the growth and stagnation of moor development. A rough outline can be created based on the origin of the water sustaining the moor – precipitation or mineral water (see graphic).
Moors fed exclusively by rainwater, so-called high moors (ombrogenous), form only in areas with high rainfall and low evaporation rates, frequently in conjunction with low mid-year temperatures – they are typically found on the ridges of low mountain ranges.
Overgrown bodies of water occur when open bodies of water become overgrown – either from below due to the accumulation of silt or from the surface of the water when quacking bogs take shape. Peat formation ends when the body of water is fully overgrown. It is, however, possible for a secondary moor type, a raised moor for example, from an overgrown moor when the environmental conditions are conducive to this.
Boggy moors arise when the water level rises and the water collects in hollows or depressions. Some things that might case a rise in water levels include: Reduced water runoff (blocking dams, blocking layers) or an increase in the water supplied (climate change, forest clearing). If the water level fluctuates, the peat on the surface will start to rot due to the introduction of oxygen – which decreases water retention.
Basin moors form in depressions. They are characterized and caused by the formation of an impermeable layer unique to the moor that covers the mineral substrate, thus causing water buildup and stimulating peat formation. Due to its location in a basin, the water level continues to rise and peat continues to form. Basin moors cover relatively small spaces and could not survive off rainwater alone.
So-called flooding moors can form in areas that are periodically flooded by bodies of water (oceans, rivers, lakes). Peat in these moor locations are characterized by thick layers of decay that arise during periods when the peat is dry and not flooded. Furthermore, the peat also contain a great many mineral components deposited when the moor is flooded by a waterway.
Percolation moors develop in areas with high water levels year-round and almost always appear in conjunction with running groundwater; percolation moors fed by rainwater can only develop in areas with heavy rainfall. The peat here is coarsely porous, absorptive, and can absorb quite a lot of water as it trickles through the peat.
Slope and spring moors are trickle moors feed by groundwater and spring water close to the surface, tight groundwater pathways. Due to the periodic fluctuation in the water level, some of the peat does rot, which contributes to a lower ground permeability. This means that water does not flow through the peat beds, but rather trickles. In low mountain ranges, these types of moors are often the starting point for the development of raised moors.
Sources: SUCCOW, M. (2001); COLDITZ, G. (1994)