Ecology (Habitat) Flora & Nutrition In The Different Geographical Areas (Part ~ 3 Mongolia)

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Mongolia

Mongolia is an upland country and its climate is largely determined by it continental position and its high altitude. It is also far away from the influences of the oceans. There are significant differences between summers and winters and also of daytime and night time periods. The large bulk of Mongolia's land lies around 1500m above sea level, and between mountain ranges vast plateaus stretch between 1500m and 2000m, and often between 2000m and 3000m. The Altai regions boast the highest mountain peaks in excess of 4000m. The lowest points are found in the salt lake Hoh-Nuur in the Uldz basin which is around 552m and lies to the east of the country.

Map Showing vegetation zones of Mongolia
Map showing Vegetation zones of Mongolia

Mongolia has many distinct geographical and floral zones, and plant species in the different zones are dependent on the amount of rainfall it receives in a year. From the south of the country to the north there is a gradient of increasing precipitation. The northern parts of Mongolia have the highest precipitation levels, that being in excess of 400mm per year. Here the needle leaved forests (taiga) is found growing, and occupy many of the mountainous ranges. The dominant plant species here (72% of the total forest area) is Larix sibirica, along with Pinus sibirica (12%) Pinus sylvestris (7%) Betula platyphylla (9%) and Picea obovata (0.25%) This area also has many herbaceous species that thrive here.

As we move southwards from the upper northern zones precipitation decreases and in areas where annual precipitation is between 300-400mm it is then classed as the forest steppe zone. Here there is a rich mixture of forest areas and grasslands and because of the mountainous ranges here there is a big difference in the plant species that grow on the north facing slopes and the higher parts of the region, and the steppes on the southern slopes and in the valleys. This region is also subject to logging activities, and as a result the forest regions have diminished and been largely replaced by steppes and in particular meadow steppes. The meadow steppes have an extremely diverse range of plant species, and in particular herbaceous plants, grasses and sedges. The plant species themselves reflect the transition from forest to steppe, and often you will see stumps of larch trees, which are indications of a previous forest site.

In the zone below this where the precipitation drops below 300mm per year (200-300mm) Trees are unable to survive and grasses dominate the region. This area is known as typical steppe, or grass steppe region. It is regarded as a dry steppe when compared to the moister meadow steppe further north, and has vast stretches of grasslands. The type of steppe vegetation growing here comprise of tall and medium sized grasses in particular tussock grasses, alongside which grow several herbaceous plants and sub-shrubs. Grazing intensity here can often affect which plants are the dominant species growing in the region.

As we travel further south towards the direction of the Gobi desert area annual precipitation again drops and here it is between 100-200mm per year. This area is known as the desert steppe zone, and here vegetation becomes sparse. The desert soils here support two main types of vegetation, the stipa-allium semi-desert and the shrub semi-desert, which occupy rocky, stone/grit or sandy areas.

Stipa allium vegetation occupy vast stretches of shrubless land and is characterized by the presence of Stipa glareosa, and onion related species such as Allium polyrrhizum, A. mongolicum and Anabasis brevifolia. In contrast to this, the shrub semi-desert consists of several plant communities of tough shrubs and sub shrub species. Here plants such as Amygdalus pedunculata, Caragana leucophloea, and Zygophyllum xanthoxylon are dominant, which grow alongside grasses and allium species. Because of the harsh conditions of this region, many areas are bare and drifting sand dunes develop. The dunes themselves are often colonized by the shrub Nitraria sibirica, and on the saline solonchak soils succulent type bushes of Kalidium gracile dominate this sparsely vegetated area.

Below this zone precipitation again drops to less than a 100-150mm per year, and occurs almost exclusively in the summer, however in many years rainfall can be totally absent. This area is known as the desert zone. Here grid and stone deserts occupy most of the region and to a large extent replace the sandy deserts. *Solonchack desert areas with a high salt content in the soil occupy many regions here, and vegetation consists of shrubs and sub-shrubs, while grass and Allium species are virtually absent. Many areas here are too extreme to support plant life, and you will see hardly any plants over large areas of the land. Plant species that can survive here on the solonchak soils are usually succulent in nature, and have evolved to have a high salt content in their cells, which helps them achieve a higher water potential throughout their growing season.

Map showing mean annual precipitation in Mongolia

Mean annual precipitation in Mongolia - Hilbig 1995

The vegetation zones from north to south of Mongolia can also be further divided into altitudinal distribution of vegetation in the mountainous areas. Here the distribution of flora depends on the exposition of the mountain slope and also on latitude. Altitudinal vegetation of the Mongolian mountains in the hill belt of North Mongolia is covered by grassy steppes, whereas both grass steppes and semi-deserts occupy the Mountain areas around the Great lake basins. In the lower mountain belts of northern Mongolia one can find forest regions and the meadow steppes. The lower Montane* forests consist mainly of Siberian Larch (Larix sibirica) where as the upper montane forests consist of Siberian pine (Pinus sibirica) In southern Mongolia we can see semi-deserts, and the transaltai-Gobi and Dzuungarian Gobi both support desert and semi-desert areas. In the southern mountainous belts it is characterised by mountain steppes, with stands of Juniperus Sabina and Juniperus pseudosabina, and in the northern parts of the area there are remnants of forest. Shrubs and dwarf shrubs such as rhododendron adamsii, Betula rotundifolia, Pinus pumila, and Salix species dominate the sub alpine belt, whereas in the alpine belt we can see an upper section with alpine cushion plants being the dominant plant species on the rocks and debris, and a lower section where Kobresia is the dominant meadow plant.

*Montane-The biogeographic zone made up of relatively moist cool upland slopes below timberline that is characterized by large evergreen trees as a dominant life form.

*Solonchaks-occur where evaporation exceeds rainfall and there is a seasonal or permanent water table close to the soil surface. They have a high saline content in the soil.

NorthWest Mongolia

In north western Mongolia the Mongolian gerbil was observed inhabiting the flat plains there, where Salsola plants grows in abundance. Research studies showed 50 inhabited burrows were recorded per hectare in this region. It was also observed here that they avoided the sandy barkhans*

*A barkhan is an individual, symmetrical, crescent shaped, sandy hill formation that forms on the ridges of a transverse sand dune.

North East Mongolia

Here the Mongolian gerbil was observed to be most frequently found populating the areas where cereal grasses, Salsola and Caragana can be found in the semi-deserts of that region, and also in the sand dunes overgrown with Nitraria. They are found here populating steppes with a mixture of cereal plants, on sandy hillocks covered with Caragana shrubs, and in saline patches and around the salt marshes where Salsola plants grow in abundance.

Once again they were found near human settlements, and populations were observed in the rubbish heaps on the outskirts of the vegetable gardens.

Southern Ranges

Southern Mongolia

According to research conducted in 1958 by Tarasov, the population of gerbils observed in the Altaian Gobi region lived in the semi-deserts where wild cereal, Salsola and Lycium plants grow in abundance. Populations of the gerbil were also common in the ravines. In the Dzuungarian Gobi they were found amongst the oasis and around sand dunes where Nitraria sibirica was the dominant plant. They were most numerous near the valleys of rivers, and around human settlements. Here they were common near the crop fields and around rubbish heaps.

Bij Gol Study

A recent study conducted in the Bij-Gol region of the Dzuungarian Gobi in SW Mongolia (Dzuungarian Gobi is a part of the District of the West Gobi) reported the Mongolian gerbil still present in this region.

zoogeographic regions of Mongolia

Zoo geographic regions of Mongolia - Bannikov 1954

The Mongolian government itself established these areas in the Gobi as a protected area network, They are known as the Great Gobi strictly protected area and it was established in 1975. It is a unique untamed part of the Central Asian Desert, which possesses some extraordinary landscape, and is the living habitat of some of the most rare and vulnerable fauna and animal species in the world.

Aim and Objectives of the study

Aims and objectives were identified to determine small rodent species diversity and their ecosystems significance in the Bij-gol, and around it's vicinity. The objectives were to find out the species composition of this region and also to find out which species were dominant, and how plentiful the different species were in the region. They also identified the different habitats which provided niches for these species.

8 different Study points were chosen and were selected on their water points, flora and fauna.

The different plots distinguished by their biotopes were identified as follows,

  • Plot 1- Nanophyton-feathergrass
  • Plot 2 - Feathergrass-ephedra-onion
  • Plot 3 - Caragana-artemisia
  • Plot 4 - Anabasis- feathergrass
  • Plot 5 - Halophylus shrubs
  • Plot 6 - Feathergrass - Artemisia
  • Plot 7- Achnaterum splendens grassland
  • Plot 8 - In Fence

The fenced area was high and was an area where the local people there gathered hay after harvest. In the study the Mongolian gerbil was regularly trapped here along with the Scilly shrew, House mouse, Dwarf hamster, and Midday gerbil. This plot supported many species, as no livestock could enter, was often irrigated and also the animals had protection here from raptors and carnivores.

Results of species composition showed that in the study area one of the most commonly occurring species in the Forest steppe zone was the Mongolian gerbil, along with the Great gerbil, dwarf hamster and the Korean Field mouse. Here it was shown these species have had wide choices of food and living habitat. However it was the Yellow steppe Lemming that was the most prolific in these regions. Living alongside the Mongolian and Great gerbils in this unique habitat was the Midday gerbil and the Tamarisk gerbil. It was also noted that unique to this region were 10 different species of Jerboa. The jerboa had the largest differing species number in the region. The Jerboa is different to the Mongolian gerbil by the fact it hibernates or goes into periods of torpor during cold, harsh weather periods. Studies show that hoarding rodents such as gerbils have a distinct advantage over mammals that hibernate. The jerboa's legs, their moving apparatus, are unique, and its prolific presence here in these regions is reflective of the substrate ecology of their habitat. The soil cover, its mechanic structure, and size of the stones significantly influence the distribution of jerboa species in the Gobi.

The Bij-Gol river itself has biotopes that could represent both the Mongolian Gobi and Dzuungarian Gobi and therefore has the possibility to support the many different species that are unique to this region. The biotopes that represented the Dzuungarian Gobi were the Khonin Us, Shiirin Us and Gun Tamga Oasis. These regions are quite different and vary from a soft muddy ground steppe with Haloxylon ammodendron and Salsola plants, Hillocky steppe with stipa and Allium plants, to rocky terrain with Haloxylon ammodendron is the dominant plant. Also along the Bij-Gol river itself grow Caragana and Artemesia bushes along the muddy soil river valley.

 

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