So how does the geology of the Cairngorms National Park influence the habitats of the Park and their plants and animals?
One way is through the soil;
Soil is made of rock dust and organic material from decaying plants and animals. Healthy soil depends on the action of millions of micro-organisms which break down the organic material and mix it thoroughly. The underlying geology and rock types of an area influence the soils that form there:
- The main Cairngorms plateau is formed from granite , a hard acidic rock that breaks down into coarse grits and soils of low fertility, deficient in calcium and nitrogen and other essential chemicals that plants and animals need as nutrients.
- Around the central granite mass are areas of metamorphic rocks, largely made up of schists. These rocks break down more easily into finer silts and sands, forming more fertile loam soils. These give the most fertile soils of all and often have distinctive vegetation.
Impact of nutrients
Fewer species of plant can grow on poor, acidic soils than on lime-rich soils. Thus, the high Cairngorms have a more limited number and variety of plant species, especially arctic–alpine species, than some other Scottish mountains.
Impact of grazing pressure
The vegetation growing on calcareous rocks and their soils is more nutritious than on acidic soils and is favoured by grazing animals. Consequently, deer and sheep tend to be concentrated on the lower hills and valleys, with the richer soils of the schists. This in turn affects the vegetation by trampling and manure enrichment and the vegetation may begin to change from dwarf shrub heath to grassland.
The granite areas show a lower density of these herbivores, and largely unmodified vegetation.