The effect of environmental conditions that occurs in different patches within a landscape creates a changing kaleidoscope of species composition and diversity.
The biosphere is characterized by a series of gradients of physical factors, as for instance temperature gradients from the Arctic to the tropics or gradients from shore to bottom in bodies of water.
Usually the conditions and the organisms adapted to them change gradually along a gradient. It is known that each species' population has its own particular habitat requirements.
The concept of ecological gradient may be defined as a graduation from one ecosystem to another when is no sharp boundary between the two. It is the joint expression of associated community and complex environmental gradients.
The gradients may be straight-forward such as latitude, elevation, temperature, light, soil depth, soil nutrition, soil moisture, pH, water level, precipitation, or more complicated such as the acid base-poor vs. neutral, base- and bicarbonate-rich gradient, soil redox potential, oxygen concentration, etc.
These gradients represent a complex community property in which we cannot look for a single explanation involving only one causal factor.
This experiment considered in spatial gradients. These gradients symbolize the concentration profiles of a certain state variable or system feature within a certain area.
In this experiment, we investigate the change in vegetation, climate, soil and others factors with the change in height. With the change of altitude for every 100 m air temperature decreases by 1 °C.
With the increase of the altitude varies distribution of trees and also condition of climate. Trees reduces with height, this is associated with the transition to a more severe climate. Therefore, with altitude of species diversity is reduced due to more difficult conditions. But this process does not depend of the altitude. This is due to the influence of various factors such as temperature, climate, pH and others.
The aim of this experiment was to show changes in species diversity with altitude, depending on various factors.
The study was conducted on the territory Northern Norway. Sampling was done at three different altitudes. The altitude of 100 m is located in the region Skibotn, the altitude 300 meters - in the region Helligskogen and 500 meters - in the Kilpisjarvi. Also pay attention to the climate and soil.
At an altitude of 100 meters prevails more oceanic climate, 300 m is intermediate climate and 500 m is characterized by more continental climate.
At each altitude of had selected plot, where was conducted a 20 m long transects. At a distance of 20 m every 5 meters in 1 m2 were measured and taken the following data and samples: species richness (number of vascular plant species), functional richness (number of functional groups), largest leaf size, tree height.
At altitudes of 100 m were taken soil samples where in the laboratory had measured pH. Samples were taken from different of soils type (bedrock): soils rich limestone, soils poor quartz.
In the course of the experiment results were follows:
Most rich species diversity was observed at altitude of 300 m on rich limestone bedrock, where the maximum number of species was 13.3, average number of species 11. The lowest species diversity was observed at altitude of 500 m on rich limestone bedrock, where the maximum number of species was 5.5, the average number of species 4.4.
The highest number of functional groups was observed at altitude of 300 m on rich limestone bedrock, where the maximum number was 4.6, average number of species 3.7. The lowest number of functional groups was observed at altitude of 500 m on rich limestone bedrock, where the maximum number of species was 3.2, the average number of species 2.3.
Largest leaf size was observed at altitude of 300 m on rich limestone bedrock, where the leaf size was 9.6 and the smallest size of the leaf was at altitude of 500 m on rich bedrock - 2.3.
The pH on rich bedrock varies from 5.2 at altitude of 100 m to 4.6 at altitude of 500 m, and on poor bedrock from 4.7 to 4.9 respectively.
Height of trees was the highest at altitude of 100 m on poor bedrock where the height is 9 m and lowest at altitude of 500 m on poor bedrock where the height is 3 m.
According to the results found that the richest species diversity is observed at altitude of 300 m on rich limestone bedrock, and very poor species diversity is observed at altitude of 500 m on rich limestone bedrock. Thus, the most favorable place for the growth of vegetation is the altitude of 300 m.
Thus, were examined changes in species diversity with altitude and tried to give some explanations, but have considered factors are not enough for a full explanation.