The tundra in Mexico It 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; it is common for the ground to freeze overnight. In relation to the vegetation, it does not present arboreal elements.
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..
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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 shrubby 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 features we have the following:
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.
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 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, greater insolation and intensity of the wind is received, so 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 per 100 m in an altitudinal range.
This biome is located in the altitudinal strip between coniferous forests and periglacial deserts (nival zone). The distribution is discontinuous and isolated, since it only occurs in the peaks of the highest mountains 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 barely 50 km2.
There is a great abundance of tillering grasses which, in general, are of restricted distribution. Species of the genus Festuca are frequent such as F. livida Y F. tolucensis.
Among other grasses are Agrostis tolucensis, Calamagrostis tolucensis (white straw) and Muhlenbergia species (M. nigra Y M. macroura).
Succulent plants such as Echeveria secunda (shell) and Dabra jorullensis (fake shell). 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 stands out (Juniperus monticola). Likewise, in various areas we find the chickpea (Lupinus montanus) and the calm heart (Lupinus mexicanus). This last species has allelopathic effects due to its high content of alkaloids.
Ferns of the genus can occasionally be found Elaphoglossum, and in the higher areas there is a predominance of mosses such as Bryoerythrophyllum jamesonii, Bartramia potosica Y Leptodontium flexifolium. On the other hand, lichens of the Umbilicaria genus are abundant in the subnival zone..
Vegetation changes in the range of the alpine tundra. According to the altitude ranges, some authors differentiate the zacatonal (3800-4300 m) and the superzacatonal (4300-4900 m).
The vegetation tends to be more or less open. In the lower parts there is a predominance of tillering grasses Calamagrostis tolucensis Y Festuca tolucensis, and some tall grasses may also be featured. In certain areas some bushes may grow (Juniperus).
In the highest part (> 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 coverage and bryophytes (mosses) are beginning to be observed.
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..
In this ecosystem the fauna is scarce due to the extreme conditions. Some rodents of the genus are presented Cratogeomys known as gophers, and the volcano bunny or teporingo (Romerolagus diazi).
Among 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 over 4500 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 stands out (Ambistoma altamirani), a species of salamander.
As for birds, the peregrine falcon (Falco peregrinus) and the big crow (Corvux corax).
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