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671.
672.
Dr A. O. Aweto 《The Environmentalist》1995,15(1):10-15
Summary This paper evaluates the rates of organic carbon diminution in the soil under monospecific tree plantations of teak, gmelina, rubber, oil palm, cashew and coffee. The differences between the organic carbon status of their soils and soil under nearby natural rain forest vegetation are compared. Annual rates of organic carbon decrease for the 0–10 cm soil layer, varied from 82.1 kg ha–1 for cashew to 316.7 kg ha–1 for oil palm. The tree plantations appear to release more carbon dioxide from the soil into the atmosphere than the natural forest. They therefore, appear to have the potential of contributing towards global warming — a threat they are supposed to mitigate. 相似文献
673.
Dr. M. V. Angel 《The Environmentalist》1982,2(1-2):1-17
Considerable concern has been recently expressed in conservation circles about the potential threat to oceanic trench ecosystems.
Here, the geological origin in environmental characteristics and biological significance of the trenches are reviewed.
Each trench provides a unique and isolated habitat, consequently endemicity has been found to be high at the specific level
in each trench that has been adequately studied. However, the remoteness from primary food sources greatly reduces the richness
of the fauna.
The physical instability of trench habitats deriving from their high level of seismic activity, will result in the organisms
being pre-adapted to mechanical disturbance. The main threats are either direct through poisoning by toxic chemicals or indirect
through the decoupling of the trench habitat from its primary food source, or reduction in oxygen levels caused either by
eutrophication or reduction in flushing rates.
Only direct threats are considered as being at all dangerous, and any incident would be restricted to a single trench system.
these threats could be reduced by rerouting vessels carrying toxic cargoes and by improving the effectiveness of the London
Dumping Convention.
The internationally agreed criteria for the selection of sites for any proposed seabed disposal of radioactive waste exclude
the use of trenches for this purpose. 相似文献
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Climate change has serious effects on the setting up and the operation of natural ecosystems. Small increase in temperature
could cause rise in the amount of some species or potential disappearance of others. During our researches, the dispersion
of the species and biomass production of a theoretical ecosystem were examined on the effect of the temperature–climate change.
The answers of the ecosystems which are given to the climate change could be described by means of global climate modelling
and dynamic vegetation models. The examination of the operation of the ecosystems is only possible in huge centres on supercomputers
because of the number and the complexity of the calculation. The number of the calculation could be decreased to the level
of a PC by considering the temperature and the reproduction during modelling a theoretical ecosystem, and several important
theoretical questions could be answered. 相似文献
680.
PD Dr. Rolf Altenburger Dr. Dana Kühnel Martin Bittens Dr. Birgit Daus Dr. Werner Brack Dr. Florian Centler Prof. Dr. Hauke Harms Dr. Martin Thullner Dr. Lukas Y. Wick Prof. Dr. Kai-Uwe Goss Prof. Dr. Frank-Dieter Kopinke Dr. Katrin Mackenzie Dr. Anja Miltner PD Dr. Matthias Liess Dr. Rainer Wennrich Dr. Anne E. Berns PD Dr. Peter Burauel 《Environmental Sciences Europe》2010,22(4):502-506