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601.
Element fluxes through European forest ecosystems and their relationships with stand and site characteristics 总被引:1,自引:0,他引:1
de Vries W van der Salm C Reinds GJ Erisman JW 《Environmental pollution (Barking, Essex : 1987)》2007,148(2):501-513
This paper describes a European wide assessment of element budgets, using available data on deposition, meteorology and soil solution chemistry at 121 Intensive Monitoring plots. Input fluxes from the atmosphere were derived from fortnightly or monthly measurements of bulk deposition and throughfall, corrected for canopy uptake. Element outputs from the forest ecosystem were derived by multiplying fortnightly or monthly measurements of the soil solution composition at the bottom of the root zone with simulated unsaturated soil water fluxes. Despite the uncertainties in the calculated budgets, the results indicate that: (i) SO4 is still the dominant source of actual soil acidification despite the generally lower input of S than N, due to the different behaviour of S (near tracer) and N (strong retention); (ii) base cation removal due to man-induced soil acidification is limited; and (iii) Al release is high in areas with high S inputs and low base status. 相似文献
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A simplistic aggregate model of global economic activity supports a 50-year visioning exercise with targets defined in terms of aggregate measures of global equity (convergence) and sustainability (contraction). Some ambitious combinations of these targets turn out to be infeasible even under the most favorable modeling assumptions. No contraction target (no reduction in fossil fuel consumption relative to the present) was possible, for example, if international capital transfers pushed per capita incomes in low-income countries above 33% of levels achieved in high-income countries. Lower prices for renewable alternatives to exhaustible resources generally made sustainability targets easier to achieve, but lower prices for renewable resources also made equity targets more difficult to achieve. Improved substitution between capital and labor made equity targets easier to achieve in relative terms, but improved substitution between capital and labor could make any given sustainability target more or less difficult to achieve. All the results suggest that it is possible to overstate the purported conflict between achieving sustainability and equity targets. The very transfers of international capital that would promote relative equity between high-income and low-income countries could also work to spread the incidence of achieving any sustainability target more evenly across their boundaries.Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
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W. J. W. Botzen J. C. J. H. Aerts J. C. J. M. van den Bergh 《Mitigation and Adaptation Strategies for Global Change》2013,18(2):229-244
Climate change is expected to increase the frequency and intensity of natural disasters. Adaptation investments are required in order to limit the projected increase in natural disaster risks. Adaptation measures can reduce risk partially or completely eliminate risk. The literature on behavioural economics suggests that individuals rarely undertake measures that limit risk partially, while they may place a considerable value on measures that reduce risk to zero. This is studied for a case of adaptation to climate change and its effects on flood risk in the Netherlands. In particular, we examine whether households are willing to invest in elevating newly built structures when this is framed as eliminating flood risk. The results indicate that a majority of homeowners (52%) is willing to make a substantial investment of €10,000 to elevate a new house to a level that is safe to flooding. Differences between willingness to pay (WTP) for flood insurance and WTP for risk elimination through elevation indicate that individuals place a considerable value on the latter adaptation option. This study estimates that the “safety premium” which individuals place on risk elimination is approximately between €35 and €45 per month. The existence of a safety premium has important implications for the design of climate change adaptation policies. The decision to invest in elevating homes is significantly correlated with the expected negative effects of climate change, perceptions of flood risks, individual risk attitudes, and living close to a main river. 相似文献
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Erik J. van Waveren 《Natural resources forum》2007,31(3):188-197
This paper examines the effects of growing land pressure on the distribution and quality of cropland allocations on customary tenured land (CTL) in Swaziland. Within the wider Sub‐Saharan context, the reform of indigenous tenure systems is now generally seen as a process of adaptation rather than replacement. The legal recognition of (existing and future) user rights is considered a practical way forward. This essentially rights‐based approach may divert attention from technical inadequacies indigenous systems may have, particularly under conditions of increasing land pressure. The case of CTL substantiates such shortcomings. CTL has seen a marked growth in population and land allocations since Independence. This had led to concerns on the land distribution efficiency in view of the improved agricultural production required to sustain the increasing number of rural households. By analysing historical changes in the number, size and quality of cropland allocations in selected rural communities, this paper demonstrates the occurrence of a high degree of inconsistency in cropland distribution at the community level, as well as inefficient land distribution at higher levels of scale. These shortcomings threaten the sustainability of the local agricultural production systems, and will need to be addressed in any meaningful reform process. 相似文献