ECOTONE: CHARACTERISTICS AND EXAMPLES - ENVIRONMENT - 2025

The ecotone is the transition zone between two or more different adjacent ecological systems. Ecological systems can be biomes, landscapes, ecosystems, communities, or populations.

They are formed due to the presence of gradients of physical environmental variables such as climate, topography, soil characteristics or the presence of another specific community or population.

Ecotone closed-Mata atlantica. Source: www.flickr.com

Ecotones can be gradual or abrupt, depending on how the physical environmental variables affect the different individuals, which depends on their adaptive morphological, physiological and reproductive strategies.

These transition zones are of great environmental importance. They tend to be areas of high biodiversity, especially those that occupy large areas and are stable over time.

characteristics

Scale

The transition between two ecological systems occurs due to changes in variables that limit the ecological processes that affect the distribution of species. These factors are associated with different scales, depending on the ecological systems under study.

Ecotones on a biome scale are determined by climatic environmental factors such as the water balance and the temperature of the air masses, as well as by topographic factors such as the presence of rivers and geographical features.

On a landscape scale, ecotones are also influenced by climate and topography. In addition, they are affected by soil characteristics such as pH, rock composition, among others.

Finally, in community or population ecotones, the composition and distribution of the species is influenced by the interaction between species in the adjacent communities or populations. Response that depends on the demographic characteristics of each of the species involved.

Thus, in smaller scale ecotones there are more physical environmental factors and ecological processes that determine their origin and composition.

Biodiversity

Ecotones are areas with great biodiversity. Species associated with each of the interacting ecological systems are usually found in this transition zone.

Furthermore, with the creation of new microhabitats it is possible to observe new species specifically adapted to this area.

The pattern of biodiversity in the different ecotones is influenced by various factors. Some of them are mentioned below:

• The size and distribution of the ecotone and adjacent ecosystems.
• The temporal stability of the ecotone.
• The intensity of the environmental gradient that affects the ecotone.
• The demographic characteristics of the species that are established in the ecotone.

Examples

The tundra border - boreal forest

The forest-tundra boundary is an example of an ecotone in two different biomes characterized by different climates.

The tundra develops in the northern polar areas of the planet, up to 63 ° North latitude. In this area the climate is very cold, with a maximum annual temperature that does not exceed 10 ° C and an average rainfall of 250 mm per year.

With this climate, the soil is frozen throughout the year forming a layer called permafrost.

During the summer, some of the snow melts and accumulates on the surface, due to the permafrost preventing its infiltration. Thaw water collects in cold swamps called peat bogs.

The boreal forests (Canada) or taigas (Russia) are located south of the tundras and north of the steppe.

The climate is less intense than in the polar zone, with temperatures ranging from 30 ° C below zero to 19 ° C. Annual rainfall can reach 450 mm per year.

The ecotone between these two large biomes that constitutes the transition zone is called the forest-tundra. It ranges from a few kilometers in North America to 200 km in Europe.

It is an area with a fragmented landscape, with areas covered by dense forests, alternated by areas dominated by lichens and heather, without the presence of trees.

This transition zone is more diverse than the separate tundra and boreal forest ecosystems, containing species from both biomes.

Forest transition-

In the tropical Andes mountains, the altitudinal limit of the forests is defined by a transition zone between the páramo and the paramero or subparamo forest.

This transition zone is the result of interactions between factors such as temperature, the maximum altitude of the mountain range, the annual variations in rainfall, solar exposure, topographic and edaphic characteristics.

Due to these interactions, the ecotone appears at a variable elevation, forming undulations and patches of forests that penetrate the areas dominated by vegetation typical of the moors.

There is a tendency for the ecotone to be located at lower altitudes in those lower or isolated mountains, in less humid slopes and with marked rainfall regimes, and in areas with the presence of human activities exposed to fire, grazing and agriculture.

Wetlands

Wetlands are ecotones between terrestrial and aquatic ecosystems that play an extremely important role in environmental sanitation.

They participate in the capture of sediments, in the absorption of nutrients and in the release of chemical substances into the atmosphere, improving the quality of the waters.

They intervene in the regulation of nitrogen concentrations in rivers, increased as a consequence of the excessive use of pesticides in industrial agriculture.

The vast majority of this nutrient is captured by wetland vegetation, turning it into living biomass. Another part is released into the atmosphere through the denitrification process.

Later, with the death of the vegetation, the nutrients are deposited in the soil for long periods of time.

Thus, between 60% and 75% of the dissolved nitrogen in a river can be captured in the first 20 m of a wetland.

Due to the high efficiency of wetlands in controlling the flow and retention of nutrients, the conservation and management of these ecosystems is important.

The oases

Oases are spaces with bodies of water in the interior of a desert, characterized by the presence of vegetation.

In the desert of Peru is the Huacachina lagoon 60 km from the Pacific coast. It is a lagoon originated by the outcrop of underground currents.

As a result of the presence of water, abundant vegetation develops in the oasis. Several species of palm trees and a species of tree legumes known locally as hurango or carob (Prosopis pallida) are mainly recognized.

The presence of water and vegetation attracts the presence of animals. The migratory birds that use this territory for rest and food stand out.

References

1. Di Castri, F, Hansen, AJ and Holland, MM The International Union of Bi 01 agi cal Sciences 17.
2. Llambi, LD. (2015). Structure, diversity and dynamics of the vegetation in the forest-páramo ecotone: review of the evidence in the Merida mountain range. Acta Boilógica Colombiana, 20 (3): 5-19.
3. ED and Sanderson, SC (1998). Ecotones: Introduction, Scale, and Big Sagebrush Example. In: McArthur. ED, Ostler, WK and Wambolt, CL Proceedings: Shrubland Ecotones. Rocky Mountain Research Station. Ogden, UT. 299pp.
4. Pirela, M. (2012). Spatial Patterns and Functional Responses During the Establishment of Woody Species in a Seasonal Savanna. 138 pp.
5. Risser, PG 1995. The status of the science examining ecotones. BioScience. 45: 318-325.