Rila Monastery Nature Park Management Plan - part - usaid

February 2004
Brown forest soils (Cambisols)
These are situated in the 800 to 1,600-1,800-meter altitudes and are one of the most
common types of soil. Their profile includes all genetic horizons: A, B and C. The
thickness of the dead vegetation cover on the forest floor varies from 3 to 10 cm; the
humus accumulation horizon is poor – 5 to 25 cm; the illuvial horizon is between 80-
100 cm and is not of sufficient density. Horizon C consists of rock fragments mixed
with other, finer weathering products. Soils of this type are light to medium-weight,
highly porous in texture and water-permeable. They are divided in two sub-types:
light and dark.
The light-brown forest soils are characteristic of lower altitudes, where they cover
drier and more exposed slopes. At higher altitudes, towards the upper limit of the
forest-soil area, wooded, shaded and more humid mountain slopes are dominated by
the dark-brown forest soils, which determine the higher timber productivity of forests
growing on them.
Mountain-forest dark soils (Umbriс Cambisols)
These are located at altitudes between 1,600 and 2,000-2,200m asl. With them, too,
the soil profile comprises all three horizons: A, B and C. The dead-vegetation forest
floor cover is ca. 10+ cm; the A-horizon is over 30 cm; the B-horizon, between 0.5
and 1 m in thickness. These soils have a larger humus content (7-10%), which gives
them their dark-brown color, and a pH reaction of 4.0-5.0.
Mountain-grassland soils (Molic Cambisols)
This type of soil is common at altitudes of 2,000-2,200 to 2,500 m and is formed at
very harsh climatic conditions. They have a tendency of forming a peat layer. The
grassy vegetation supplies large quantities of organic matter, which, at high humidity
and low temperatures, decomposes and mineralizes very slowly. Depending on the
terrain and the moisture content, these soils become waterlogged or, alternatively,
trigger processes similar to the chernozem soil development process. The soil profile
is incomplete, with the A-horizon being of great depth and density, while the Bhorizon
is about 10 cm or less. The mountain-grassland soils have a great fertility
potential, yet the abundance of nutrients are, most often, in a form difficult for plants
to absorb. The soil moisture is sufficient, but the soil aeration is inhibited. For this
reason, these soils support mostly grassy and shrubby communities. They have an
acid reaction, pH = ca. 4.5.
At 2,500m asl there dominate mountain-grassland soils in combinations with various
primitive soils, bare rocks and screes.
Rila Monastery Nature Park
Management Plan -Draft
2004 - 2013
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