differences originate from both climate and soil formation processes. High-altitude
mountain ranges generally receive much higher rainfall, both in quantity and
intensity (high torrentiality) than lowlands. Moreover, sunshine incidence in
mountain slopes is usually higher than in high latitudes and largely depends on the
aspect. In south-facing slopes solar radiation is high, even in winter time, thus
reducing the snow cover and the chance of frost layers. In mountain ranges of
temperate areas, even on north-facing slopes, winter temperatures are warmer than
in high latitude areas and because of the higher precipitation the snow cover is
thicker. Consequently, mountain soils are better insulated, with high solar radiation
and thus their frost layer is less thick and not permanent in most cases. The
reduction or lack of permafrost of the mountain soils contributes to their general
good drainage and thus wet soils (i.e. peatlands) in mountain landscapes are mainly
confined to bottom areas and depressions, and they are not widespread. Conversely,
in mountain slopes high rainfall and good drainage speeds up soil formation processes. However, natural disturbances also linked to the slopes such as soil erosion,
rock fall, landslides, avalanches and snow ablation play an important role in
rejuvenating mountain soils. As a result of these complex interactions and because
of its diverse geomorphology mountain landscapes hold a large spatial variability
that is depicted in both soils and vegetation.
Soils of mountain areas tend to be young and highly influenced by their bedrock
and physiographic properties. The wide range of soil types occurring in mountain
regions is driven by microtopography, slope and aspect which, as stated above,
define the snowpack and melting patterns that influence soil temperature, nutrient
leaching and soil moisture (Stöhr 2007). Young mountain soils occur in
well-drained areas and are classified as Leptosols or Regosols. Leptosols are thin
soils, extremely gravelly and/or stony and with strong limitations to rooting.
Regosols are weakly developed mineral soils in unconsolidated materials that occur
in less stony areas and are typically highly erodible. On calcareous areas Rendzic or
Chromic Leptosols dominate. Rendzic leptosols have a surface layer with high
accumulation of organic matter and calcium carbonate. Chromic leptosols have a
red surface layer and low or no calcium carbonate content. On siliceous bedrock,
Regosols and the extremely thin Lithic leptosols are commonly found. But in stable
and well-drained surfaces soils are often more developed, being common Dystric
Cambisols and different types of Podzols. These latter two soil types show a thick
and well-developed acidic horizon, but Podzols contain a subsurface horizon with
illuvial amorphous organic matter and/or Al and Fe oxides. Finally, Histosols occur
in poorly drained areas. These last soils evolve from incompletely decomposed
plant remains and thus their features are quite independent of the bedrock type
(IUSS Working Group WRB 2015).
Mountain soils in temperate areas usually have a high organic matter content, as
shown in some regional soil C maps (Baritz et al. 2010; Doblas-Miranda et al.
2013). Although plant biomass in alpine grasslands is much lower than in forests,
their soil C stocks are also generally high (Table 9.1) and comparable to forested
areas (Berninger et al. 2015). The large amount of soil C in alpine environments is
related to the high residence time of organic matter in the soil compared to the
9 Are Soil Carbon Stocks in Mountain Grasslands …
209
mountain ranges generally receive much higher rainfall, both in quantity and
intensity (high torrentiality) than lowlands. Moreover, sunshine incidence in
mountain slopes is usually higher than in high latitudes and largely depends on the
aspect. In south-facing slopes solar radiation is high, even in winter time, thus
reducing the snow cover and the chance of frost layers. In mountain ranges of
temperate areas, even on north-facing slopes, winter temperatures are warmer than
in high latitude areas and because of the higher precipitation the snow cover is
thicker. Consequently, mountain soils are better insulated, with high solar radiation
and thus their frost layer is less thick and not permanent in most cases. The
reduction or lack of permafrost of the mountain soils contributes to their general
good drainage and thus wet soils (i.e. peatlands) in mountain landscapes are mainly
confined to bottom areas and depressions, and they are not widespread. Conversely,
in mountain slopes high rainfall and good drainage speeds up soil formation processes. However, natural disturbances also linked to the slopes such as soil erosion,
rock fall, landslides, avalanches and snow ablation play an important role in
rejuvenating mountain soils. As a result of these complex interactions and because
of its diverse geomorphology mountain landscapes hold a large spatial variability
that is depicted in both soils and vegetation.
Soils of mountain areas tend to be young and highly influenced by their bedrock
and physiographic properties. The wide range of soil types occurring in mountain
regions is driven by microtopography, slope and aspect which, as stated above,
define the snowpack and melting patterns that influence soil temperature, nutrient
leaching and soil moisture (Stöhr 2007). Young mountain soils occur in
well-drained areas and are classified as Leptosols or Regosols. Leptosols are thin
soils, extremely gravelly and/or stony and with strong limitations to rooting.
Regosols are weakly developed mineral soils in unconsolidated materials that occur
in less stony areas and are typically highly erodible. On calcareous areas Rendzic or
Chromic Leptosols dominate. Rendzic leptosols have a surface layer with high
accumulation of organic matter and calcium carbonate. Chromic leptosols have a
red surface layer and low or no calcium carbonate content. On siliceous bedrock,
Regosols and the extremely thin Lithic leptosols are commonly found. But in stable
and well-drained surfaces soils are often more developed, being common Dystric
Cambisols and different types of Podzols. These latter two soil types show a thick
and well-developed acidic horizon, but Podzols contain a subsurface horizon with
illuvial amorphous organic matter and/or Al and Fe oxides. Finally, Histosols occur
in poorly drained areas. These last soils evolve from incompletely decomposed
plant remains and thus their features are quite independent of the bedrock type
(IUSS Working Group WRB 2015).
Mountain soils in temperate areas usually have a high organic matter content, as
shown in some regional soil C maps (Baritz et al. 2010; Doblas-Miranda et al.
2013). Although plant biomass in alpine grasslands is much lower than in forests,
their soil C stocks are also generally high (Table 9.1) and comparable to forested
areas (Berninger et al. 2015). The large amount of soil C in alpine environments is
related to the high residence time of organic matter in the soil compared to the
9 Are Soil Carbon Stocks in Mountain Grasslands …
209