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Using estimates of land suitable for restoration in woodlands, grasslands, and deserts, as well as estimates of the rate at
which restoration can proceed, we estimate that carbon storage in these biomes can range up to 0.8 billion tons of carbon
per year (Gt C/yr), for a combination of land management strategies. This corresponds to a reduction in atmospheric buildup
of 0.5 Gt C/yr, which represents up to 15% of the average annual atmospheric carbon buildup in the next century, 3.5 Gt C/yr,
assuming the IPCC 92d scenario. A global strategy for reducing atmospheric carbon dioxide concentration will require the implementation
of multiple options. The advantage of carbon storage in restored drylands is that it comes as a side benefit to programs that
are also justifiable in terms of land management. 相似文献
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Drylands (41 and 35% of global land and population, respectively) have the lowest biological productivity of any ecosystem,
contain populations with the highest growth rates on earth, and share a significant fraction of global poverty for which desertification
is implicated. A global assessment of the available information indicates that the inherent low productivity of drylands,
when combined with other adverse factors, can generate poverty. It additionally indicates that while the drylands may exist
in a locally stable and sustainable state, this is readily destabilized by non-linear, threshold-crossing transitions to an
alternative steady-state leading to desertification, poverty and conflicts. The “desertification paradigm” (human and climatological
pressures driving overexploitation of land resources, leading to desertification, poverty and reduced security) is challenged
by its “counter-paradigm” (adversity elicits innovation, leading to ingenuous solutions for avoiding desertification). But
the latter does not account for the inevitability of continued and increasing pressure on the finite dryland resources, expected
to be further exacerbated by a globally increasing need for agricultural land. A companion paper points out that this situation
can be avoided by reducing dependence on land productivity, through adoption of “alternative livelihoods.” These livelihoods,
while economically advantageous, reduce pressure on land resources. 相似文献
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Adaptation as a Political Process: Adjusting to Drought and Conflict in Kenya’s Drylands 总被引:3,自引:3,他引:0
In this article, we argue that people’s adjustments to multiple shocks and changes, such as conflict and drought, are intrinsically
political processes that have uneven outcomes. Strengthening local adaptive capacity is a critical component of adapting to
climate change. Based on fieldwork in two areas in Kenya, we investigate how people seek to access livelihood adjustment options
and promote particular adaptation interests through forming social relations and political alliances to influence collective
decision-making. First, we find that, in the face of drought and conflict, relations are formed among individuals, politicians,
customary institutions, and government administration aimed at retaining or strengthening power bases in addition to securing
material means of survival. Second, national economic and political structures and processes affect local adaptive capacity
in fundamental ways, such as through the unequal allocation of resources across regions, development policy biased against
pastoralism, and competition for elected political positions. Third, conflict is part and parcel of the adaptation process,
not just an external factor inhibiting local adaptation strategies. Fourth, there are relative winners and losers of adaptation,
but whether or not local adjustments to drought and conflict compound existing inequalities depends on power relations at
multiple geographic scales that shape how conflicting interests are negotiated locally. Climate change adaptation policies
are unlikely to be successful or minimize inequity unless the political dimensions of local adaptation are considered; however,
existing power structures and conflicts of interests represent political obstacles to developing such policies. 相似文献
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El Gamri T 《Environmental monitoring and assessment》2004,99(1-3):57-73
Sudan is the largest country in Africa with an area of about 2.5 million km2; the country hosts a population of about 31 million people. About two-thirds of the country area is located within arid and
semi-arid regions. Recently, especially during the last half of the previous century, these regions were subject to various
forms of land degradation. This paper discusses the general prospects and constraints of desert agriculture. It also presents
a detailed case study of West Omdurman, which is located in a semi-desert climatic zone. The ambitious plans to utilise the
area for agricultural production were initiated because of the relatively fertile soil, availability of water and the proximity
of the area to marketing and export centres. The paper discusses the different land use systems experienced in the area, reasons
for failure are identified and possible remedies discussed. In addition, constraints facing the proposed West Omdurman Canal
Project are also discussed. Finally, the paper reviews the major research findings of Rawakeeb Dryland Research Center with
regard to promoting agricultural productivity. 相似文献
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Causes and consequences of woody plant encroachment into western North American grasslands 总被引:3,自引:0,他引:3
As woody plants encroach into grasslands, grass biomass, density and cover decline as wood plant biomass, density and cover increase. There is also a shift in location of the biomass from mostly belowground in the grasslands to aboveground in the woodlands. In addition, species richness and diversity change as herbaceous species are replaced by woody species. This is not a new phenomenon, but has been going on continually as the climate of the Planet has changed. However, in the past 160 years the changes have been unparalleled. The process is encroachment not invasion because woody species that have been increasing in density are native species and have been present in these communities for thousands of years. These indigenous or native woody species have increased in density, cover and biomass because of changes in one or more abiotic or biotic factors or conditions. Woody species that have increased in density and cover are not the cause of the encroachment, but the result of changes of other factors. Globally, the orbit of the Earth is becoming more circular and less elliptical, causing moderation of the climate. Additional global climate changing factors including elevated levels of CO2 and parallel increases in temperature are background factors and probably not the principal causes directing the current wave of encroachment. There is probably not a single reason for encroachment, but a combination of factors that are difficult to disentangle. The prime cause of the current and recent encroachment appears to be high and constant levels of grass herbivory by domestic animals. This herbivory reduces fine fuel with a concomitant reduction in fire frequency or in some cases a complete elimination of fire from these communities. Conditions would now favor the woody plants over the grasses. Reduced grass competition, woody plant seed dispersal and changes in animal populations seem to modify the rate of encroachment rather than being the cause. High concentrations of atmospheric CO2 are not required to explain current woody plant encroachment. Changes in these grassland communities will continue into the future but the specifics are difficult to predict. Density, cover and species composition will fluctuate and will probably continue to change. Increased levels of anthropogenic soil nitrogen suggest replacement of many legumes by other woody species. Modification and perhaps reversal of the changes in these former grassland communities will be an arduous, continuing and perhaps impossible management task. 相似文献
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Jonathan Davies 《Natural resources forum》2008,32(3):175-184
Sustainable development for Africa's mobile pastoralists is slowly becoming a reality. Success depends to a large extent on understanding the dynamics of drylands environments, accepting the logic of customary mobile livestock keeping, and enabling effective governance. Appropriate investment in pastoralism requires a clear understanding of the values that are attached to it and innovative approaches to marketing of the goods and services that emanate from the system. To make development truly sustainable it is imperative that the environmental services of pastoralism are recognised, rewarded and promoted. Constraints to sustainable pastoral development include low and misdirected public and private investment, weak security of resource rights, low human capital, weak pastoral voice and poor governance. Successful and sustainable development is observed in pastoral regions where customary governance has been legitimized, resource rights secured and economic development of the pastoral sector, as opposed to transformation of livestock keeping, has prevailed. This article presents state‐of‐the‐art knowledge on sustainable pastoralism, gathered through the GEF/UNDP/IUCN World Initiative for Sustainable Pastoralism (WISP), with data and case studies taken from three recently published WISP reports: “Global Economic Review of Pastoralism”, “Pastoralism as Conservation in the Horn of Africa”, and “Policy Impacts on Pastoral Environments”. 相似文献
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