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.
Wandel und Kontinuität in der mobilen Tierhaltung der Mongolei
Die Mongolei gehort weltweit zu denjenigen Landern, wo die mobile Tierhaltung eine bedeutende Rolle spielt. Seit dem Ende des Sozialismus hat sich in der mobilen Tierhaltung ein tief greifender Wandel vollzogen. Anfang der 1990er Jahre wurden die kollektiv gehaltenen Tierbestande der viehwirtschaftlichen Vereinigungen (Negdel) privatisiert und an alle Mitglieder verteilt. Viele so genannte ?neue Nomaden? nahmen die mobile Tierhaltung auf. Es werden die Hintergrunde und Kennzeichen des jungen Wandels und die Hauptprobleme in der mobilen Tierhaltung der Mongolei aufgezeigt. Weiterhin werden neue, unter marktwirtschaftlichen Bedingungen entstandene Formen raumlich-sozialer Organisation dargestellt. Die Autoren kommen zu dem Schluss, dass landliche Regionalentwicklung nur durch einen holistischen Ansatz ereicht werden kann. Verringerung der Tierzahlen, Einfuhrung neuer rechtlicher Regelungen zur Erreichung eines okologisch angepassten Weidemanagements, Aufbau von tierische Produkte verarbeitenden Betrieben sowie Ausbau der technischen und sozialen Infrastruktur sind wichtige Ziele, deren Erreichung eine dauerhafte Entwicklung im landlichen Raum und damit die Kontinuitat der mobilen Tierhaltung in der Mongolei auch in Zukunft gewahrleisten konnte.
Reduced translocation of cadmium from roots is associated with increased production of phytochelatins and their precursors.
Cadmium (Cd) is a non-essential trace element and its environmental concentrations are approaching toxic levels, especially in some agricultural soils. Understanding how and where Cd is stored in plants is important for ensuring food safety. In this study, we examined two plant species that differ in the distribution of Cd among roots and leaves. Lettuce and barley were grown in nutrient solution under two conditions: chronic (4 weeks) exposure to a low, environmentally relevant concentration (1.0 μM) of Cd and acute (1 h) exposure to a high concentration (5.0 mM) of Cd. Seedlings grown in solution containing 1.0 μM CdCl₂ did not show symptoms of toxicity and, at this concentration, 77% of the total Cd was translocated to leaves of lettuce, whereas only 24% of the total Cd was translocated to barley leaves. We tested the hypothesis that differential accumulation of Cd in roots and leaves is related to differential concentrations of phytochelatins (PCs), and its precursor peptides. The amounts of PCs and their precursor peptides in the roots and shoots were measured using HPLC. Each of PC₂₋₄ was synthesized in the barley root upon chronic exposure to Cd and did not increase further upon acute exposure. In the case of lettuce, no PCs were detected in the root given either Cd treatment. The high amounts of PCs produced in barley root could have contributed to preferential retention of Cd in barley roots.