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1.
Soybean farming has brought economic development to parts of South America, as well as environmental hopes and concerns. A substantial hope resides in the decoupling of Brazil's agricultural sector from deforestation in the Amazon region, in which case expansive agriculture need not imply forest degradation. However, concerns have also been voiced about the potential indirect effects of agriculture. This article addresses these indirect effects for the case of the Brazilian Amazon since 2002. Our work finds that as much as thirty-two percent of deforestation, or the loss of more than 30,000 km2 of Amazon forest, is attributable, indirectly, to Brazil's soybean sector. However, we also observe that the magnitude of the indirect impact of the agriculture sector on forest loss in the Amazon has declined markedly since 2006. We also find a shift in the underlying causes of indirect land use change in the Amazon, and suggest that land appreciation in agricultural regions has supplanted farm expansions as a source of indirect land use change. Our results are broadly congruent with recent work recognizing the success of policy changes in mitigating the impact of soybean expansion on forest loss in the Amazon. However, they also caution that the soybean sector may continue to incentivize land clearings through its impact on regional land markets.  相似文献   

2.
Forest transition theory describes a reversal in land-use trends for a given area, from a period of net forest area loss, to a period of net forest area gain. Some assume that such forest gain necessarily equates with biodiversity conservation. We question this assumption, based on research conducted in Oaxaca, Mexico. In Oaxaca's northern highlands, low intensity forest use and rotational (milpa) agriculture have led to pronounced spatial heterogeneity in forest structure and composition, and created a high-biodiversity forest-agriculture mosaic. In the Zapotec community of San Juan Evangelista Analco and the Chinantec community of Santiago Comaltepec, as across much of Oaxaca, fewer people are farming; farmers are cultivating less land, working closer to settlements, and growing fewer crop varieties. Widespread agricultural abandonment has initiated unprecedented changes in ecological succession, patch size, and edge effects, which we speculate will be having an impact on the biodiversity of the landscape mosaic. Our work suggests that the decline of land use activity may result in a gradual loss of the forest-agriculture mosaic, leading to localised declines in biodiversity, despite (or because of) extensive forest resurgence. These findings support the view that indigenous cultures in Oaxaca and Mexico should not be seen as an environmental constraint but rather as an agent of landscape renewal that allows for both cultural and biological diversity to flourish, a reality that national and international conservation bodies need to more fully recognise and incorporate into policy.  相似文献   

3.
Negative environmental impacts of violent conflict have been observed worldwide. Whether or not active global conflicts are declining in number remains hotly debated, the number of countries entering post-conflict periods is on the rise, and the impact of this transition on land cover changes remains poorly understood. In Colombia, though large-scale armed conflict has concluded, the post-conflict period represents an ongoing threat to forest conservation, putting at risk commitments to meet global conservation goals and even those stipulated in the peace accord. This paper aims to assess land cover change associated with the Colombian conflict in the Andes-Amazon region between 1988 and 2019. First, we use the Landsat archive to map land cover and characterize the spatial patterns of change at the regional level. Second, to empirically identify the effect of conflict on land cover change, we employ a difference-in-difference approach using local conflict events data. During conflict (1988–2011), land cover in the Andes-Amazon remained relatively stable, however during the post-conflict period (2012–2019), the conversion from forest to agriculture increased by 40%. We find that forest cover surrounding conflict events (1 km radius) decreased significantly, on average by ~ 19% during conflict, which accelerated to ~ 30% in the post-conflict period. Similarly, agriculture expansion is most substantial during the post-conflict period, but exclusively in municipalities with population below the 50th percentile. Landscape metrics show that in peripheral municipalities (<50th), agriculture occurs in clumped distributions during the conflict period. Meanwhile, during the post-conflict period, this expansion happens more quickly, with significantly greater agricultural patch sizes than during the conflict period. We conclude that a slow implementation of conservation governance, the emergence of illegal land markets, and illicit land uses (i.e., coca and illegal cattle ranching) may accelerate land cover change in the coming years.  相似文献   

4.
Land cover is a crucial, spatially and temporally varying component of global carbon and climate systems. Therefore accurate estimation and monitoring of land cover changes is important in global change research. Although, land cover has dramatically changed over the last few centuries, until now there has been no consistent way of quantifying the changes globally.In this study we used long-term climate, soils data along with coarse resolution satellite observations to quantify the magnitude and spatial extent of global land cover changes due to anthropogenic processes. Differences between potential leaf area index, derived from climate-soil-leaf area equilibrium and actual leaf area index obtained from satellite data were used to estimate changes in land cover.Forest clearing for agriculture and irrigated farming in arid and semi-arid lands are found to be two major sources of climatically important land cover changes. Satellite derived Spectral Vegetation indices (SV I) and surface temperatures (T s) show strong impact of land cover changes on climatic processes. Irrigated agriculture in dry areas increased energy absorption and evapotranspiration (ET) compared to natural vegetation. On the other hand, forest clearing for crops decreased energy absorption andET. A land cover classification and monitoring system is proposed using satellite derivedSV I andT s that simultaneously characterize energy absorption and exchange processes. This completely remote sensing based approach is useful for monitoring land cover changes as well as their impacts on climate. Monitoring the spatio-temporal dynamics of land cover is possible with current operational satellites, and could be substantially improved with the Earth Observing System (EOS) era satellite sensors.  相似文献   

5.
Increased water yield and baseflow and decreased peak flow are common goals of watershed service programs. However, is the forest management often used in such programs likely to provide these beneficial watershed services? Many watershed service investments such as water funds typically change less than 10% of watershed land cover. We simulate the effects of 10% forest-cover change on water yield, low flow, and high flow in hydrologic models of 29 watersheds around the world. The forest-cover changes considered are: forest restoration from degraded natural lands or agriculture, forest conversion to agriculture, and forest conversion to urban cover. We do not consider grassland restoration by removal of alien tree species from riparian zones, which does increase water yield and low flow. Forest restoration from locally-predominant agricultural land resulted in median loss in annual water yield of 1.4%. Forest restoration reduced low flow and high flow by ∼3%. After forest restoration, low flow increased in ∼25% of cases while high flow and water yield declined in nearly all cases. Development of forest to agriculture or urban cover resulted in a 1–2% median increase in water yield, a 0.25–1% increase in low flow, and a 5–7% increase in high flow. We show that hydrologic responses to forest cover changes are not linearly related to climate, physiography, initial land cover, nor a multitude of watershed characteristics in most cases. These results suggest that enhanced streamflow watershed services anticipated from forest restoration or conservation of 10% or less of a watershed are generally modest.  相似文献   

6.
Forest transitions: towards a global understanding of land use change   总被引:5,自引:0,他引:5  
Places experience forest transitions when declines in forest cover cease and recoveries in forest cover begin. Forest transitions have occurred in two, sometimes overlapping circumstances. In some places economic development has created enough non-farm jobs to pull farmers off of the land, thereby inducing the spontaneous regeneration of forests in old fields. In other places a scarcity of forest products has prompted governments and landowners to plant trees in some fields. The transitions do little to conserve biodiversity, but they do sequester carbon and conserve soil, so governments should place a high priority on promoting them.  相似文献   

7.
Policy initiatives in India, such as the Social Forestry Program and later the Joint Forest Management, were introduced for their co-benefits, including forest protection, employment opportunities, and added income for communities living in and around the forests. The evolution of these forest policies is critically reviewed. It is argued that India is perfectly positioned to benefit from climate change mitigation efforts, due to a rich, albeit chequered, history in forest management. National forestry policies are examined to assess how they can complement international climate change mitigation instruments, such as the Clean Development Mechanism (CDM) and the more recent Reduced Emissions from Deforestation and Forest Degradation (REDD or REDD+ with conservation, sustainable management of forests, and enhancement of forest carbon stocks) and aid national sustainable development objectives. There is a need to heed the experiences from India's evolving forest policies, particularly those concerning land tenure and resource rights, which lack specificity within international mechanisms. The active engagement of rural communities must be integral to any programmes that make any claim to development and to environmental integrity as a whole.

Policy relevance

India's forestry programmes are examined for their effectiveness in informing international initiatives such as the CDM and REDD+. Forestry policies in India can evolve to complement international climate mitigation tools. By examining current and historical forest legislation, and their subsequent impacts, it is shown how communities can sustain their system of forest management and retain/obtain rights to land and resources under the CDM and REDD+. Looking for such synergies within existing national policies to implement newer international initiatives can greatly facilitate and increase the momentum of global environmental change.  相似文献   

8.
Long-term studies of land system change can help providing insights into the relative importance of underlying drivers of change. Here, we analyze land system change in Germany for the period 1883–2007 to trace the effect of drastic socio-economic and institutional changes on land system dynamics. Germany is an especially interesting case study due to fundamentally changing economic and institutional conditions: the two World Wars, the separation into East and West Germany, the accession to the European Union, and Germany's reunification. We employed the Human Appropriation of Net Primary Production (HANPP) framework to comprehensively study long-term land system dynamics in the context of these events. HANPP quantifies biomass harvests and land-use-related changes in ecosystem productivity. By comparing these flows to the potential productivity of ecosystems, HANPP allows to consistently assess land cover changes as well as changes in land use intensity. Our results show that biomass harvest steadily increased while productivity losses declined from 1883 to 2007, leading to a decline in HANPP from around 75%–65% of the potential productivity. At the same time, decreasing agricultural areas allowed for forest regrowth. Overall, land system change in Germany was surprisingly gradual, indicating high resilience to the drastic socio-economic and institutional shifts that occurred during the last 125 years. We found strikingly similar land system trajectories in East and West Germany during the time of separation (1945–1989), despite the contrasting institutional settings and economic paradigms. Conversely, the German reunification sparked a fundamental and rapid shift in former East Germany's land system, leading to altered levels of production, land use intensity and land use efficiency. Gradual and continuous land use intensification, a result of industrialization and economic optimization of land use, was the dominant trend throughout the observed period, apparently overruling socio-economic framework conditions and land use policies.  相似文献   

9.
Historic land use can exert strong land-use legacies, i.e., long-lasting effects on ecosystems, but the importance of land-use legacies, alongside other factors, for subsequent forest-cover change is unclear. If past land use affects rates of forest disturbance and afforestation then this may constrain land use planning and land management options, and legacies of current land management may constrain future land use. Our goal was to assess if and how much land-use legacies affect contemporary forest disturbance, and the abundance of different forest types in the Carpathian region in Eastern Europe (265,000 km2, encompassing parts of Poland, Slovakia, Ukraine, Romania, Hungary, and Czech Republic). We modeled contemporary forest disturbance (based on satellite image analysis from 1985 to 2010) as a function of historic land use (based on digitized topographic maps from 1860 and 1960). Contemporary forest disturbance was strongly related to historic land use even when controlling for environmental, accessibility and socio-political variation. Across the Carpathian region, the odds of forest disturbance were about 50% higher in areas that were not forested in 1860 (new forests) compared to areas that were forested then (old forests). The forest disturbance in new forests was particularly high in Poland (88% higher odds), Slovakia (69%) and Romania (67%) and persisted across the entire range of environmental, accessibility and socio-political variation. Reasons for the observed legacy effects may include extensive plantations outside forest ranges, predominantly spruce, poplar, and black locust, which are prone to natural disturbances. Furthermore, as plantations reach harvestable age of about 70 years for pulp and 120 year for saw-timber production, these are likely to be clear-cut, producing the observed legacy effects. Across the Carpathians, forest types shifted towards less coniferous cover in 2010 compared to the 1860s and 1960s likely due to extensive historic conifer harvest, and to recent natural disturbance events and clear-cuts of forest plantations. Our results underscore the importance of land-use legacies, and show that past land uses can greatly affect subsequent forest disturbance for centuries. Given rapid land use changes worldwide, it is important to understand how past legacies affect current management and what the impact of current land management decisions may be for future land use.  相似文献   

10.
Despite recent success in reducing forest loss in the Brazilian Amazon, additional forest conservation efforts, for example, through ‘Reducing Emissions from Deforestation and Forest Degradation’ (REDD+), could significantly contribute to global climate-change mitigation. Economic incentives, such as payments for environmental services could promote conservation, but deforestation often occurs on land without crucial tenure-security prerequisites. Improving the enforcement of existing regulatory disincentives thus represents an important element of Brazil's anti-deforestation action plan. However, conservation law enforcement costs and benefits have been much less studied than for conditional payments. We develop a conceptual framework and a spatially explicit model to analyze field-based regulatory enforcement in the Brazilian Amazon. We validate our model, based on historical deforestation and enforcement mission data from 2003 to 2008. By simulating the current conservation law enforcement practice, we analyze the costs of liability establishment and legal coercion for alternative conservation targets, and evaluate corresponding income impacts. Our findings suggest that spatial patterns of both deforestation and inspection costs markedly influence enforcement patterns and their income effects. Field-based enforcement is a highly cost-effective forest conservation instrument from a regulator's point of view, but comes at high opportunity costs for land users. Payments for environmental services could compensate costs, but will increase budget outlays vis-à-vis a command-and-control dominated strategy. Both legal and institutional challenges have to be overcome to make conservation payments work at a larger scale. Decision-makers may have to innovatively combine incentive and disincentive-based policy instruments in order to make tropical forest conservation both financially viable and socially compatible.  相似文献   

11.
A plant and soil simulation model based on satellite observations of vegetation and climate data was used to estimate the potential carbon pools in standing wood biomass across all forest ecosystems of the conterminous United States up to the year 1997. These modeled estimates of vegetative carbon potential were compared to aggregated measurements of standing wood biomass from the U. S. Forest Service’s national Forest Inventory and Analysis (FIA) data set and the Carbon Online Estimator (COLE) to understand: 1) predominant geographic variations in tree growth rate and 2) local land cover and land use history including the time since the last stand-replacing disturbance (e.g., from wildfire or harvest). Results suggest that although wood appears to be accumulating at high rates in many areas of the U.S. (Northwest and Southeast), there are still extensive areas of relatively low biomass forest in the late 1990s according to FIA records. We attribute these low biomass accumulation levels to the high frequency of disturbances, which can be observed even in high production areas such as the Southeast due to frequent forest harvests. Ecosystem models like the one presented in this study have been coupled with satellite observations of land cover and green plant density to uniquely differentiate areas with a high potential for vegetative carbon storage at relatively fine spatial resolution.  相似文献   

12.
Forest inventories and remote sensing are the two principal data sources used to estimate carbon (C) stocks and fluxes for large forest regions. National governments have historically relied on forest inventories for assessments but developments in remote sensing technology provide additional opportunities for operational C monitoring. The estimate of total C stock in live forest biomass modeled from Landsat imagery for the St. Petersburg region was consistent with estimates derived from forest inventory data for the early 1990s (272 and 269 TgC, respectively). The estimates of mean C sink in live forest biomass also agreed well (0.36 and 0.34 Mg C ha–1 yr–1). Virtually all forest lands were accumulating C in live biomass, however when the net change in total ecosystem C stock was considered, 19% of the forest area were a net source of C. The average net C sink in total ecosystem biomass is quite weak (0.08 MgC ha–1 yr–1 and could be reversed by minor increases in harvest rates or a small decline in biomass growth rates.  相似文献   

13.
Forest inventories and remote sensing are the two principal data sources used to estimate carbon (C) stocks and fluxes for large forest regions. National governments have historically relied on forest inventories for assessments but developments in remote sensing technology provide additional opportunities for operational C monitoring. The estimate of total C stock in live forest biomass modeled from Landsat imagery for the St. Petersburg region was consistent with estimates derived from forest inventory data for the early 1990s (272 and 269 TgC, respectively). The estimates of mean C sink in live forest biomass also agreed well (0.36 and 0.34 Mg C ha–1 yr–1). Virtually all forest lands were accumulating C in live biomass, however when the net change in total ecosystem C stock was considered, 19% of the forest area were a net source of C. The average net C sink in total ecosystem biomass is quite weak (0.08 MgC ha–1 yr–1 and could be reversed by minor increases in harvest rates or a small decline in biomass growth rates.  相似文献   

14.
Carbon storage and catchment hydrology are influenced both by land use changes and climatic changes, but there are few studies addressing both responses under both driving forces. We investigated the relative importance of climate change vs. land use change for four Alpine catchments using the LPJ-GUESS model. Two scenarios of grassland management were calibrated based on the more detailed model PROGRASS. The simulations until 2100 show that only reforestation could lead to an increase of carbon storage under climatic change, whereby a cessation of carbon accumulation occurred in all catchments after 2050. The initial increase in carbon storage was attributable mainly to forest re-growth on abandoned land, whereas the stagnation and decline in the second half of the century was mainly driven by climate change. If land was used more intensively, i.e. as grassland, litter input to the soil decreased due to harvesting, resulting in a decline of soil carbon storage (1.2−2.9 kg C m–2) that was larger than the climate-induced change (0.8–1.4 kg C m−2). Land use change influenced transpiration both directly and in interaction with climate change. The response of forested catchments diverged with climatic change (11–40 mm increase in AET), reflecting the differences in forest age, topography and water holding capacity within and between catchments. For grass-dominated catchments, however, transpiration responded in a similar manner to climate change (light management: 23–32 mm AET decrease, heavy management: 29–44 mm AET decrease), likely because grassroots are concentrated in the uppermost soil layers. Both the water and the carbon cycle were more strongly influenced by land use compared to climatic changes, as land use had not only a direct effect on carbon storage and transpiration, but also an indirect effect by modifying the climate change response of transpiration and carbon flux in the catchments. For the carbon cycle, climate change led to a cessation of the catchment response (sink/source strength is limited), whereas for the water cycle, the effect of land use change remains evident throughout the simulation period (changes in evapotranspiration do not attenuate). Thus we conclude that management will have a large potential to influence the carbon and water cycle, which needs to be considered in management planning as well as in climate and hydrological modelling.  相似文献   

15.
In tropical Latin America, pasture land for extensive grazing continues to expand, mostly at the expense of forest cover. Until now, scientists and policy makers tackling this issue had no geographically exhaustive information at the continental level about the spatial dynamics of this process. On the basis of a land use change-modeling framework we made a projection of potential land use changes for the year 2010.The chosen modeling framework incorporates a number of essential aspects of the complexity of land use change, such as the interrelation of spatial and temporal dynamics, land use history and scale dependence. The model was provided with up-to-date, continent wide, detailed information on present land use and its location factors, selected on the basis of literature. Model inputs were established in collaboration with experts from the region.Significant statistical relations were obtained that describe land use patterns in sub-regions, giving insights into the deforestation process and its location factors. Combined with decision rules and quantitative estimates of land use change, “hot spots” of forest to pasture and crop land conversion were projected. The results envisage a predominant replacement of forest by pasture. Substantially different trends among countries are predicted, both concerning the spatial patterns of deforestation and the substitution trends between land uses. The hot spot maps also show sensitive biological areas that may be at risk.The resulting continent wide map of projected change shall help to target policy attention and measures. It also provides a context to the numerous undergoing deforestation case studies. Finally, it is proposed that the study's results be considered in the priority setting of future research on the causes of deforestation.  相似文献   

16.
Rural places are important centers of environmental and social transformation. Landholders are not only affected by socio-environmental changes, but they are influencing futures related to climate change, food security, freshwater, biodiversity, and social and economic development. Much environmental land use work understands individual landholders as rational actors, portrayed through the economic lens of “producer.” These approaches generally focus on present capacities and limitations as the principal factors contributing to land use, and the individual farm as the reference unit for decisions. Our research takes steps to expand conceptualizations of rural landholders as active and knowledgeable in envisioning, managing, and shaping environmental futures. We design and test a new approach using ecological mental maps and future imaginaries to understand land use practices through a case study in the cocoa-producing and Atlantic Forest region of Southern Bahia, Brazil. The integrated socio-perceptual (ISP) approach combines qualitative and quantitative methodologies to honor the depth of landholders’ experiences and perspectives and to allow broader regional relationships and insights to emerge. We demonstrate that the ISP approach—through 49 surveys—has the capacity to capture variation and identify patterns in ecological mental maps and future imaginaries in a population, approximate the relevant spatial scales underlying these factors, and identify relationships between these and land uses. In this context, the types of narratives landholders hold about the region’s future are associated with current forest land use on their properties. We discuss potential applications of the ISP approach for land use study and practice.  相似文献   

17.
Armed conflicts trigger region-specific mechanisms that affect land use change. Deforestation is presented as one of the most common negative environmental impacts resulting from armed conflicts, with relevant consequences in terms of greenhouse gas emissions and loss of ecosystem services. However, the impact of armed conflict on forests is complex and may simultaneously lead to positive and negative environmental outcomes, i.e. forest regrowth and deforestation, in different regions even within a country. We investigate the impact that armed conflict exerted over forest dynamics at different spatial scales in Colombia and for the global tropics during the period 1992–2015. Through the analysis of its internally displaced population (departures) our results suggest that, albeit finding forest regrowth in some municipalities, the Colombian conflict predominantly exerted a negative impact on its forests. A further examination of georeferenced fighting locations in Colombia and across the globe shows that conflict areas were 8 and 4 times more likely to undergo deforestation, respectively, in the following years in relation to average deforestation rates. This study represents a municipality level, long-term spatial analysis of the diverging effects the Colombian conflict exerted over its forest dynamics over two distinct periods of increasing and decreasing conflict intensity. Moreover, it presents the first quantified estimate of conflict's negative impact on forest ecosystems across the globe. The relationship between armed conflict and land use change is of global relevance given the recent increase of armed conflicts across the world and the importance of a possible exacerbation of armed conflicts and migration as climate change impacts increase.  相似文献   

18.
Forests play an important role in sequestrating carbon from the atmosphere. Since the 1980s, reforestation activities have been implemented in the area surrounding the Qianyanzhou Forest Experimental Station in Jiangxi Province, China. Farmland and heavily eroded waste land were replanted with fruit, orchards and forest plantations. The area surrounding the Qianyanzhou Forest Experimental Station was selected as research site to analyze the potential of reforestation in carbon sequestration. This study evaluates the variation of soil organic carbon storage under the different land use types. Soil organic carbon storage varied greatly with land use types. From 1984 to 2002, soil organic carbon storage increased 2.45 × 106 kg across eight land use types. This study demonstrates the potential for carbon sequestration in soils from reforestation. However, a complete understanding of soil carbon fluxes at the landscape scale will depend on the potential and retention period of soil organic carbon.  相似文献   

19.
基于克拉玛依减排林区的土壤和地下水取样分析结果,应用生态系统服务价值的原理与方法,分析了克拉玛依减排林区的土地开发效应.结果表明土地开发已取得一定的正效应:已开发用地土壤有机质、有效N和速效K的质量分数均高于未开发用地,土地开发明显地改善了土壤的养分状况;土壤浅层总盐量降低67.5%,土壤盐渍化现象得到有效控制;林地生态系统服务价值高达1.5417×109元/a.同时,土地开发也产生了一些负效应:地下水pH值、电导率、矿化度和全盐量均高于未开发用地,减排林区地下水化学特征不利于区域减排林效应的持续发挥;土壤有效P质量分数偏低,也不利于林区植被的生长.  相似文献   

20.
Illegal activity, such as deforestation for illicit crops for cocaine production, has been inferred as a cause of land change. Nonetheless, illicit activity is often overlooked or difficult to incorporate into causal inference models of land change. Evidence continues to build that narcotrafficking plays an important, yet often unreported, role in forest loss. This study presents a novel strategy to meet the challenge of estimating the causal effect of illicit activity in land change using consolidated news media reports to estimate the relationship between drug trafficking and accelerated forest loss in Central America. Drug trafficking organizations engage in illegal land transactions, money laundering, and territorial control that can manifest as forest conversion to agriculture or pasture land uses. Longitudinal data on 50 sub-national units over a period of 16 years (2001-2016) are used in fixed effects regressions to estimate the role of narcotrafficking in forest loss. Two narcotrafficking activity proxies were developed as explanatory variables of forest loss: i) an “official” proxy from drug seizures data within 14 sub-national units; and, ii) an “unofficial” proxy developed from georeferenced news media accounts of narcotrafficking events. The effect of narcotrafficking was systematically compared to the other well-known causes of forest loss, such as rural population growth and other conventional drivers. Both proxies indicate narcotrafficking is a statistically significant (p<0.01) contributor to forest loss in the region, particularly in Nicaragua (p<0.05, official proxy), Honduras (p<0.05, media proxy), and Guatemala (p<0.05, media proxy). Narcotrafficking variables explain an additional 5% (media proxy) and 9% (official proxy) of variance of forest loss not captured by conventional models. This study showed the ability of news media data to capture the signal of illicit activity in land use changes such as forest loss. The methods employed here could be used to estimate the causal effect of illicit activities in other land and environmental systems. Our results suggest that current drug policy, which concentrates drug trafficking in remote areas of very high cultural and environmental value, has helped to accelerate the loss of Central America's remaining forests.  相似文献   

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