870 resultados para Global change and terrestrial ecosystems
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Throughout their history mountain communities have had to adapt to changing environmental and socio-economic conditions. They have developed strategies and specialized knowledge to sustain their livelihoods in a context of adverse climatic events and constant change. As negotiations and discussions on climate change emphasize the critical need for locally relevant and community owned adaptation strategies, there is a need for new tools to capitalize on this local knowledge and endogenous potential for innovation. The toolkit Promoting Local Innovation (PLI) was designed by the Centre for Development and Environment (CDE) of the University of Bern, Switzerland, to facilitate a participatory social learning process which identifies locally available innovations that can be implemented for community development. It is based on interactive pedagogy and joint learning among different stakeholders in the local context. The tried-and-tested tool was developed in the Andean region in 2004, and then used in International Union for Conservation of Nature (IUCN) climate change adaptation projects in Thailand, Burkina Faso, Senegal, and Chile. These experiences showed that PLI can be used to involve all relevant stakeholders in establishing strategies and actions needed for rural communities to adapt to climate change impacts, while building on local innovation potential and promoting local ownership
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This paper discusses the effects of global change in African mountains, with the example of Mount Kenya. The geographical focus is the northwestern, semi-arid foot zone of the mountain (Laikipia District). Over the past 50 years, this area has experienced rapid and profound transformation, the respective processes of which are all linked to global change. The main driving forces behind these processes have been political and economic in nature. To these an environmental change factor has been added in recent years – climate change. After introducing the area of research, the paper presents three dimensions of global change that are manifested in the region and largely shape its development: Socio-political change, economic change, environmental change. For the regions northwest of Mount Kenya, climate models predict important changes in rainfall distribution that will have a profound impact on freshwater availability and management. The results presented here are based on research undertaken northwest of Mount Kenya within the framework of a series of long-term Kenyan-Swiss research programmes that began in the early 1980s.
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The present publication is the final outcome of the "Syndrome Pre-SynthesisProject" (SPSP), a preparatory project initiated in 2001 to pave the way for the NCCR North-South. The SPSP applied a transdisciplinary approach to identify research partnerships for development in 8 regions of the world. The primary aim of the present publication is to present an initial synthesis of core problems in each region, of the status and focus of related research, and of corresponding new research needs. Based on the results of this participatory process, the NCCR North-South programme has followed up on the outcomes of the regional syntheses by identifying future research aims along the general lines determined in the workshops.
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The functioning and services of Central European forests are threatened by global change and a loss of biodiversity. Nutrient cycling as a key forest function is affected by biotic drivers (e.g., dominant tree species, understory plants, soil organisms) that interact with abiotic conditions (e.g., climate, soil properties). In contrast to grassland ecosystems, evidence for the relationship of nutrient cycles and biodiversity in forests is scarce because the structural complexity of forests limits experimental control of driving factors. Alternatively, observational studies along gradients in abiotic conditions and biotic properties may elucidate the role of biodiversity for forest nutrient cycles. This thesis aims to improve the understanding of the functional importance of biodiversity for nutrient cycles in forests by analyzing water-bound fluxes of nitrogen (N) and phosphorus (P) along gradients in biodiversity in three regions of Germany. The tested hypotheses included: (1) temperate forest canopies retain atmospheric N and retention increases with increasing plant diversity, (2) N release from organic layers increases with resource availability and population size of decomposers but N leaching decreases along a gradient in plant diversity, (3) P leaching from forest canopies increases with improved P supply from recalcitrant P fractions by a more diverse ectomycorrhizal fungal community. In the canopies of 27 forest stands from three regions, 16 % to 51 % of atmospheric N inputs were retained. Regional differences in N retention likely resulted from different in N availability in the soil. Canopy N retention was greater in coniferous than in beech forests, but this was not the case on loessderived soils. Nitrogen retention increased with increasing tree and shrub diversity which suggested complementary aboveground N uptake. The strength of the diversity effect on canopy N uptake differed among regions and between coniferous and deciduous forests. The N processing in the canopy directly coupled back to N leaching from organic layers in beech forests because throughfall-derived N flushed almost completely through the mull-type organic layers at the 12 studied beech sites. The N release from organic layers increased with stand basal area but was rather low (< 10 % of annual aboveground litterfall) because of a potentially high microbial N immobilization and intensive incorporation of litter into the mineral soil by bioturbation. Soil fauna biomass stimulated N mineralization through trophic interactions with primary producers and soil microorganisms. Both gross and net leaching from organic layers decreased with increasing plant diversity. Especially the diversity but not the cover of herbs increased N uptake. In contrast to N, P was leached from the canopy. Throughfall-derived P was also flushed quickly through the mull-type organic layers and leached P was predominantly immobilized in non directly plant-available P fractions in the mineral soil. Concentrations of plant-available phosphate in mineral soil solution were low and P leaching from the canopy increased with increasing concentrations of the moderately labile P fraction in soil and increasing ectomycorrhiza diversity while leaf C:P ratios decreased. This suggested that tree P supply benefited from complementary mining of diverse mycorrhizal communities for recalcitrant P. Canopy P leaching increased in years with pronounced spring drought which could lead to a deterioration of P supply by an increasing frequency of drought events. This thesis showed that N and P cycling in Central European forests is controlled by a complex interplay of abiotic site conditions with biological processes mediated by various groups of organisms, and that diverse plant communities contribute to tightening the N cycle in Central European forests and that diverse mycorrhizal communities improve the limited P availability. Maintaining forest biodiversity seems essential to ensure forest services in the light of environmental change.
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Seaweeds are key species of the Baltic Sea benthic ecosystems. They are the substratum of numerous fouling epibionts like bryozoans and tubeworms. Several of these epibionts bear calcified structures and could be impacted by the high pCO2 events of the late summer upwellings in the Baltic nearshores. Those events are expected to increase in strength and duration with global change and ocean acidification. If calcifying epibionts are impacted by transient acidification as driven by upwelling events, their increasing prevalence could cause a shift of the fouling communities toward fleshy species. The aim of the present study was to test the sensitivity of selected seaweed macrofoulers to transient elevation of pCO2 in their natural microenvironment, i.e. the boundary layer covering the thallus surface of brown seaweeds. Fragments of the macroalga Fucus serratus bearing an epibiotic community composed of the calcifiers Spirorbis spirorbis (Annelida) and Electra pilosa (Bryozoa) and the non-calcifier Alcyonidium hirsutum (Bryozoa) were maintained for 30 days under three pCO2 conditions: natural 460±59 µatm, present-day upwelling1193±166 µatm and future upwelling 3150±446 µatm. Only the highest pCO2 caused a significant reduction of growth rates and settlement of S. spirorbis individuals. Additionally, S. spirorbis settled juveniles exhibited enhanced calcification of 40% during daylight hours compared to dark hours, possibly reflecting a day-night alternation of an acidification-modulating effect by algal photosynthesis as opposed to an acidification-enhancing effect of algal respiration. E. pilosa colonies showed significantly increased growth rates at intermediate pCO2 (1193 µatm) but no response to higher pCO2. No effect of acidification on A. hirsutum colonies growth rates was observed. The results suggest a remarkable resistance of the algal macro-epibionts to levels of acidification occurring at present day upwellings in the Baltic. Only extreme future upwelling conditions impacted the tubeworm S. spirorbis, but not the bryozoans.
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We present an update of the "key points" from the Antarctic Climate Change and the Environment (ACCE) report that was published by the Scientific Committee on Antarctic Research (SCAR) in 2009. We summarise subsequent advances in knowledge concerning how the climates of the Antarctic and Southern Ocean have changed in the past, how they might change in the future, and examine the associated impacts on the marine and terrestrial biota. We also incorporate relevant material presented by SCAR to the Antarctic Treaty Consultative Meetings, and make use of emerging results that will form part of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report.
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In the five-year period 2005-09, Brazil has dramatically reduced carbon emissions by around 25% and at the same time has kept a stable economic growth rate of 3.5% annually. This combination of economic growth and emissions reduction is unique in the world. The driver was a dramatic reduction in deforestation in the Amazonian forest and the Cerrado Savannah. This shift empowered the sustainability social forces in Brazil to the point that the national Congress passed (December 2009) a very progressive law internalising carbon constraints and promoting the transition to a low-carbon economy. The transformation in Brazil’s carbon emissions profile and climate policy has increased the potentialities of convergence between the European Union and Brazil. The first part of this paper examines the assumption on which this paper is based, mainly that the trajectory of carbon emissions and climate/energy policies of the G20 powers is much more important than the United Nations multilateral negotiations for assessing the possibility of global transition to a low-carbon economy. The second part analyses Brazil’s position in the global carbon cycle and public policies since 2005, including the progressive shift in 2009 and the contradictory dynamic in 2010-12. The final part analyses the potential for a transition to a low-carbon economy in Brazil and the impact in global climate governance.
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Summary. In recent months, the migratory impacts of environmental degradation and climate change have gained increased worldwide attention. In response to the publication of the EC Staff Working Document on Climate Change, Environmental Degradation and Migration, this policy brief critically outlines current themes and issues that surround this global phenomenon, specifically the findings of current international research which frame the discussions on terminology and current legal, political and institutional conceptual debates. Several proposals were put forward during a Policy Forum in January 2013. Firstly, there is a need for tailored and actionable research outputs that take into account political pressures and realities on the ground. Secondly, migration and climate policies would be clearly boosted through the elaboration of a common policy-oriented research agenda of which elements were put forward at the event. Finally, efficient communication tools and channels could be developed to transfer research findings to policy-makers.
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The globally warm climate of the early Pliocene gradually cooled from 4 million years ago, synchronous with decreasing atmospheric CO2 concentrations. In contrast, palaeoceanographic records indicate that the Nordic Seas cooled during the earliest Pliocene, before global cooling. However, a lack of knowledge regarding the precise timing of Nordic Seas cooling has limited our understanding of the governing mechanisms. Here, using marine palynology, we show that cooling in the Nordic Seas was coincident with the first trans-Arctic migration of cool-water Pacific mollusks around 4.5 million years ago, and followed by the development of a modern-like Nordic Seas surface circulation. Nordic Seas cooling precedes global cooling by 500,000 years; as such, we propose that reconfiguration of the Bering Strait and Central American Seaway triggered the development of a modern circulation in the Nordic Seas, which is essential for North Atlantic Deep Water formation and a precursor for more widespread Greenland glaciation in the late Pliocene.
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"May 1986."
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Mode of access: Internet.
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Mode of access: Internet.
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"PA-1497."