The effects of anthropogenic impact on plant and soil cover in Mongolia.
Under the prevailing variable natural conditions nomadic pastoralism was the most suitable form of land use in Mongolia and the neighboring countries in the past. Furthermore, small areas were used for agriculture in some regions. Therefore, anthropogenic influence was present throughout history. In the forest steppe zone this led to the disappearance of forest sites which then gave way to meadow steppe. The severe impact on the natural pastures by continuous increase of livestock herding and other human activities was perceptible during the socialist period. But since the 1990s, after the transition to market economy, this impact has increased greatly and a great number of degradation features and irreversible damages in the plant and soil cover can be observed now. Especially in the vicinity of the Mongolian capital Ulaanbaatar, along the north-south road corridor from Russia to the Chinese border, but also in some western regions of the country herders concentrate their livestock in search for better marketing opportunities. Especially there, the vegetation in vast areas is overgrazed by biting and trampling to such an extent that its regeneration is endangered. Degraded and devastated pasture types with a decrease of valuable forage plants and a high increase of ruderal elements can be found in these grasslands. Characteristic sequences of pasture degradation are presented here. The degradation effects steppes and desert steppes as well as reed, mire, and meadow vegetation in the river valleys and lowlands. In the desert regions saxaul vegetation is especially threatened. In some cases after degradation of the plant cover these degradation processes effect soil cover, too. Impacts on soil cover caused by ploughing of virgin land, by ploughing of long term used arable land, and by irrigation are the main reasons for soil degradation. Also recreational activities in the vicinity of settlement centers and traffic along the tracks lead to detrimental vegetation and soil cover changes. Unsystematic forest clearing goes on at a high level and often results in irreversible soil degradation.
Plant communities of the Mongolian Transaltay Gobi
Here we present the first detailed phytosociological description of the plant communities of the Transaltay Gobi, the driest region within Outer Mongolia. It was originally gazetted as a national park by the Mongolian parliament in 1976, which included also the Dzungarian basin in south-western Mongolia. The status of the Great Gobi A National Park in the Transaltay Gobi, and the Great Gobi B National Park in the Dzungarian Gobi was later raised to the level of Strictly Protected Area. Since the area hosts many endangered wildlife species, we offer an initial vegetation description, which is necessary to understand the habitats of this arid ecosystem. Based on a modified Braun-Blanquet approach we designated eight zonal vegetation units, most of which are impoverished regional variants of vegetation types previously described from adjacent regions; most units contain several sub-units. The altitudinal gradient reflects the climatic regime in the study area; therefore the vegetation distribution follows the precipitation gradient regarding both vegetation cover and diversity. The most important diagnostic species are typical drought–adapted central Asian ele-ments, namely Haloxylon ammodendron, Ephedra przewalskii, Reaumuria songarica and Anabasis brevifolia. Three new associations were designated based on our vegetation data. 
 
 
 
The main determinant for the riparian vegetation types is apparently groundwater availability, leading to locally high soil salt contents due to the high evaporation in the region. Poplar stands, reed beds and Tamarix stands are the characteristic vegetation types of the oases in the working area. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 
 
Pflanzengesellschaften der mongolischen Transaltai Gobi 
 
Der vorliegende Text stellt die erste detaillierte Beschreibung der Pflanzengesellschaften der Transaltai Gobi dar, der trockensten Region der Auseren Mongolei. Ursprunglich wurde das Gebiet 1976 durch das Mongolische Parlament als Nationalpark ausgewiesen, der die Dzungarische Senke im Sud-westen der Mongolei mit einschloss. Die beiden Nationalparks Grose Gobi A und Grose Gobi B wurden spater in die hohere Schutzkategorie “Streng Geschutztes Gebiet” eingestuft. Die Region beherbergt zahlreiche bedrohte Tierarten; die hier vorgestellte Vegeta-tionsbeschreibung ist somit eine notwendige Grundlage fur das Verstandnis der Habitate in diesem ariden Okosystem. Basierend auf der Braun–Blanquet Methode, die wir leicht modifi-ziert haben, wurden acht zonale Vegetationseinheiten ausgewiesen, von denen die meisten verarmte regionale Varianten von vorher schon aus benachbarten Regionen beschriebenen Vegetationstypen sind. Zahlreiche Vegetationseinheiten enthalten mehrere Untereinheiten. Die Hohenzonierung der Vegetation spiegelt das klimatische Regime des Untersuchungsgebietes wider; daher folgt die Verteilung der Vegetation dem Niederschlagsgradienten, und zwar sowohl im Bezug auf die Vegetationsdeckung als auch im Bezug auf die Diversitat. Die wichtigsten di- agnostischen Arten sind typische an Trockenheit angepasste zentral-asiatische Elemente, namentlich Haloxylon ammodendron, Ephedra przewalskii, Reaumuria songarica und Anabasis brevifolia. Auf Grundlage unserer Vegetationsaufnahmen wurden drei neue Assoziationen ausgewiesen. 
 
 
 
Die wichtigste bestimmende Eigenschaft fur die extrazonalen Vegetationstypen ist offensichtlich die Verfugbarkeit von Grundwasser; diese fuhrt aufgrund der hohen Verdunstungsraten zu lokal sehr hohen Salzkonzentrationen. Pappel-, Schilf- und Tamariskenbestande sind charakteristische Vegetationstypen der Oasen des Untersuchungsgebietes.
Sanddünenvegetation im Uvs‐nuur‐Becken (Mongolei und Tuwa/Russland)
Im vorliegenden Beitrag werden die Pflanzengesellschaften auf den Dunenstandorten in den Sandgebieten auf mongolischer und tuwinischer Seite des Uvs-nuur-Beckens dargestellt und tabellarisch belegt. Sie werden in neu aufgestellte Vegetations-Klassen, -Ordnungen und -Verbande eingegliedert. 
 
 
 
Auf noch aktiven, ungefestigten Dunen sind Gesellschaften der Brometea korotkyi mit der Ordnung der Brometalia korotkyi und ihrem einzigen Verband Bromion korotkyi ausgebildet. 
 
 
 
Hedysaro fruticosi-Leymetum racemosi ass. nov. Bromus korotkyi-Gesellschaft Psammochloa villosa-Gesellschaft Calamagrostis epigeios-Gesellschaft Auf festgelegtem Sand dichter bewachsener alter Dunengebiete siedelt die Sandsteppen-Assoziation des Hedysaro fruticosi-Stipetum krylovii Hilbig et al. 1999. 
 
 
 
Sie gehort innerhalb der Klasse der Agropyretea cristati zur Ordnung der Stipetalia krylovii mit dem einzigen Verband Stipion krylovii. 
 
 
 
Auch Subassoziationen und Ruderalisierungs-Facies werden in beiden Klassen dargestellt. 
 
 
 
Sand dune vegetation in the Uvs-nuur basin (Mongolia and Tuva/Russia). 
 
 
 
In the present paper the plant communities of dune habitats in the sand massifs of the mongolian and tuvinian part in the Uvs-nuur basin are described and documented with vegetation tables. They are placed in new vegetation classes, orders and alliances. 
 
 
 
The communities of the Brometea korotkyi with the order of Brometalia korotkyi and its only alliance of Bromion korotkyi are developed on still active and unstabilized dunes. 
 
 
 
Hedysaro fruticosi-Leymetum racemosi ass. nov. Bromus korotkyi community Psammochloa villosa community Calamagrostis epigeios community. 
 
 
 
The sand steppe association of Hedysaro fruticosi-Stipetum krylovii Hilbig et al. 1999 settles on stabilized sand of denser grown old dune areas. It belongs within the class of Agropyretea cristati to the order Stipetalia krylovii with the only alliance Stipion krylovii. 
 
 
 
Subassociations and ruderalized facies are also described in both classes.