Zonation

The most illustrative examples of vegetation zonation are found in locations where environmental conditions vary strongly at a shortdistance. Here below this phenomenon is lined out for coastal and a high mountain vegetation. Zonation, though in a less pronounced way, can be found in the district of Nijmegen along the banks of the Hatertse and Wijchense Fens.
 

Zonation
	Zonation in the vegetation on the banks of the Hatertse Fens

 

Example 1: coastal vegetation
Ath the Northsea coast of the the Netherlands a number of environmental factors can be named that change seen from the coast line along a perpendicular land inwards. Three factors in this profile decrease rapidly at a short distance, namely the salinity, wind velocity and mechanical influence of moving sand particles. One factor that increases is for example the formation of a stable soil. The zonation that arises shows a transition from a band without vegetation to avery open system with only a few plants adapted to extreme conditions, like Sand Couch and See Rocket, to an open grassland dominated by Marram Grass. Behind the first row of dunes the landscape changes to a more closed grassland and brushwood (low shrubs vegetation with Seabuckthorn, Sweet Briar, Dog-rose, Honey Suckle and Wild Privet). More landinward the inner dune wood can be found in which is tall trees occur, like Birch, Aspen, Oak and Sycamore.
 

Example 2: high mountain

Vegetation zonation in mountains
Vegetation zonation along the slopes of a mountain, from low to high altitude: deciduous tree forest, needle trees forest, (dwarf) bushes, Alm meadows, open grassland, cushion plants, mosses and lichens, Barren rocks.

At a much greater scale a vegetation zonation can be found in a mountain like for examples in the Alps. Differences in altitude can ange froma vallye at 800-1200 m high to barren rocks at 3500-4000 m high. Environmental conditions that can vary strongly depending on the altitude are:

• Shortening of the vegetation season due to temperatures below the freezing point and long periods of snow coverage
• Low noctual temperatures also in summer
• High (diurnal) temperatures due to high levels of irradiation by the sun; besides a high proportion of ultraviolet light a high altitude
• Strong wind at high altitude
• More precipitation at increasing height

From low to high the zonation can be described as follows:
Deciduous forest followed by needle trees and (dwarf)bushes vegetation. Above the timber line at about 2200 m dense (close) grasslands (alm meadows) can be found and thereabove open grass land. Even higher, only sparse cushion plants grow, followed by a vegetation of mosses and lichens and finally (nearly) barren rocks.