TUNDRA IN MEXICO: CHARACTERISTICS, LOCATION, FLORA AND FAUNA - GEOGRAPHY - 2024

The tundra in Mexico is an ecosystem that occurs in high mountain areas, within an altitude range between 3,800 and 5,000 meters above sea level. It is located on the top of high Mexican mountains; Most are volcanoes of the Transvolcanic Axis, with the exception of the Tacaná volcano on the border with Guatemala.

Average annual temperatures are between 3 and 5 ° C, and daily temperature fluctuations are extreme; the ground often freezes overnight. Regarding the vegetation, it does not present arboreal elements.

Alpine tundra on the Iztaccíhualt volcano. Source: pixabay.com

The vegetation is dominated by tillering grasses known as zacatones, which is why the Mexican tundra is called zacatonal; other names that are given are alpine pasture or high moor. In the lower areas there is the blue juniper, and in the higher areas there are a lot of mosses.

Among the fauna, the volcano bunny or teporingo stands out. Among the birds we find the peregrine falcon and snakes such as the transvolcanic rattlesnake, as well as some lizards and salamanders.

General characteristics

The tundra biome occurs in areas near the poles. One of its most outstanding characteristics is the presence of permafrost (permanently frozen layer of deep soil). In addition, the vegetation is made up of herbaceous and bushy plants.

The alpine tundra occurs in the high mountains of tropical and subtropical latitudes with climatic conditions similar to the tundra. It differs from the Arctic and Antarctic tundra by the absence of permafrost and some climatic characteristics.

This ecosystem receives different names in the American continent: in the high mountains of the Andes the slightly more humid areas are known as páramo, while in the drier slopes it is called puna.

In Mexico the alpine tundra is known as alpine prairie, highland páramo or zacatonal. Among its most outstanding characteristics we have the following:

Floor

Because this biome is located on the transvolcanic axis, the soil is derived from volcanic rocks. They are generally classified within the Andosols, the texture is mainly sandy and they are slightly acidic. In addition, they are porous and dark in color, with a high content of organic matter.

It is generally high in moisture content, at least in the deeper layers. Permafrost is absent, but the topsoil frequently freezes overnight.

Weather

The average annual temperature is in a range between 3 and 5 ° C. Extreme minimum temperatures reach down to -10 ° C.

The daily thermal oscillation is very marked, so that the freezing point can be reached throughout the year. The coldest month is February, with an average temperature of 2.8 ° C. The warmest month is usually April, with an average temperature of 5.8 ° C.

Average annual rainfall ranges between 600 and 800 mm. The driest months are from December to April; between May and October 85% of the precipitation falls in the area. However, a percentage of this rain falls as snow, which can remain on the ground for long periods.

At higher altitudes, a greater insolation and intensity of the wind is received, so the evapotranspiration is higher. Likewise, the incidence of ultraviolet light tends to be high. The duration of ice on the ground increases at the rate of one hour for every 100 m in an altitudinal range.

Location

This biome is located in the altitudinal strip between the coniferous forests and the periglacial deserts (snow zone). The distribution is discontinuous and isolated, since it only occurs in the highest mountain peaks in Mexico.

The mountains with heights greater than 4000 meters correspond mostly to the volcanoes of the Transvolcanic Axis, which covers an area of ​​approximately 360 km2. Another of the high Mexican mountains with alpine tundra is the Tacaná volcano, located on the border with Guatemala.

One of the highest areas is the Citlaltépetl or Pico de Orizaba. This volcano reaches a height of 5610 meters and is located between the states of Puebla and Veracruz.

The Popocatépetl, Iztaccíhualt and Nevado de Toluca are located in the basin of Mexico, with heights of between 5500 and 4600 meters. In this region the alpine tundra covers an area of ​​just 50 km2.

Flora

There is a great abundance of tillering grasses which, in general, are of restricted distribution. Species of the genus Festuca such as F. livida and F. tolucensis are frequent.

Other grasses include Agrostis tolucensis, Calamagrostis tolucensis (white straw), and Muhlenbergia species (M. nigra and M. macroura).

Succulent plants like Echeveria secunda (conchita) and Dabra jorullensis (false conchita) are common. There is also an abundance of representatives of the Asteraceae family and various species of Arenaria (Caryophyllaceae).

Among the bushy plants that grow in the lower areas, the blue juniper (Juniperus monticola) stands out. Likewise, in various areas we find the chickpea (Lupinus montanus) and the tranquil heart (Lupinus mexicanus). This last species has allelopathic effects due to its high content of alkaloids.

Occasionally ferns of the genus Elaphoglossum can be found, and in the higher areas there is a predominance of mosses such as Bryoerythrophyllum jamesonii, Bartramia potosica and Leptodontium flexifolium. On the other hand, lichens of the Umbilicaria genus are abundant in the subnival zone.

Vegetation structure

Vegetation changes in the distribution range of the alpine tundra. According to the altitude ranges, some authors differentiate between the zacatonal (3800-4300 m) and the superzacatonal (4300-4900 m).

Zacatonal

The vegetation tends to be more or less open. In the lower parts there is a predominance of the tillering grasses Calamagrostis tolucensis and Festuca tolucensis, and some tall grasses may also be present. In certain areas some bushes (Juniperus) can grow.

At the highest point (> 4200 m) the soil tends to be more stony, and it freezes and thaws almost daily. The clumps are less dense, there is less grass cover and bryophytes (mosses) are beginning to be observed.

Superzacatonal

In the strip that goes from 4,300 to 4,400 meters of altitude there are patches of tillering grasses. These reach heights of up to 10 cm, forming very small bearings or clumps.

Later, at altitudes above 4500 meters, vascular plants do not appear. Large quantity of cushion-shaped mosses grows in these areas and various associations of lichens are frequent.

Fauna

In this ecosystem the fauna is scarce due to the extreme conditions. There are some rodents of the genus Cratogeomys known as gophers, and the volcano bunny or teporingo (Romerolagus diazi) is also frequent.

Among the reptiles, there are species of lizards that are capable of growing in these extreme temperature environments. For example, the transvolcanic rattlesnake (Crotalus triseriatus) can be found up to above 4,500 meters of altitude.

We also find the mountain garter snake (Thamnophis scalaris), which is endemic to this ecosystem and is considered threatened. Among the amphibians, the axolotl (Ambistoma altamirani), a species of salamander, stands out.

As for birds, the peregrine falcon (Falco peregrinus) and the great crow (Corvux corax) can reach these heights.

References

1. Almeida L, M Escamilla, J Giménez, A González and A Cleef (2007) Alpine vegetation of the Popocatépetl, Iztaccíhuatl and Nevado de Toluca volcanoes. In: Luna I, JJ Morrone and D Espinosa (eds.) Biodiversity of the trans-Mexican volcanic belt. The presses of science, Mexico DF. P 267-286.
2. Giménez J, M Escamilla and L Almeida (2009) Data on the altimontana hygrophilous vegetation of the Iztaccíhuatl volcano (Mexico) Lazaroa 30: 109-118.
3. Loranca S, R Rodríguez, A Bautista and C Cuatianquiz (2013) New bird records in La Malinche National Park, Tlaxcala, Mexico. Acta Zoológica Mexicana 29: 441-447.
4. Rzedowski J (1978) Vegetation of Mexico. Limusa. Mexico, D F. 432 pp.
5. Venegas C and J Manjarrez (2011) Spatial patterns of the specific richness of Thamnophis snakes in Mexico. Mexican Journal of Biodiversity 82: 179-191.