Search

We undertake a synthesis of the most relevant results from the presentations at the meeting 'Plant-Soil Carbon Below-Ground: The Effects of Elevated CO2' (Oxford-UK, September 1995), many of which are published in this Special Issue. Below-ground responses to elevated [CO2] are important because the capacity of soils forlong-term carbon sequestration. We draw the following conclusions: (i) several ecosystems exposed to elevated [CO2] showed sustained increased CO2 uptake at the plot level for many years. A few systems, however, showed complete down-regulation of net CO2 uptake after several years of elevated [CO2] exposure; (ii) under elevated [CO2], a greater proportion of fixed carbon is generally allocated below-ground, potentially increasing the capacity of below-ground sinks; and (iii) some of the increased capacity of these sinks may lead to increased long-term soil carbon sequestration, although strong evidence is still lacking. We highlight the need for more soil studies to be undertaken within ongoingecosystem-level experiments, and suggest that while some key experiments already established should be maintained to allow long term effects and feedbacks to take place, more research effort should he directed to mechanisms of soil organic matter stabilization. [ABSTRACT FROM AUTHOR]

There is currently great concern over the possible adverse effects of atmospheric de position and other regionally distributed pollutants on plants and plant communitics. In Europe and North America there are major research efforts to determine whether such pollutants damage plants or affect ecosystem processes. A topic of growing concern is the possibility of genetic or evolutionary effects of pollutants. Past research has demonstrated that individuals, populations and varieties of a particular species can differ in their response to pollutants. Although such differences have been documented, the importance of evolutionary responses to regional, low level but chronic pollution remains to be established. The significance of regional chronic pollution is that effects on plants may no longer be limited to heavily industrialized or populated areas, but rather may also occur in virtually all natural ecosystems., (Copyright © 1988. Published by Elsevier Ltd.)