Rosewood occidentalism and orientalism in Madagascar     

《Geoforum》2017

As both a lucrative timber commodity and endangered species, rosewood ties the forests of Madagascar to the far ends of the globe. While the United States and Europe fund rosewood conservation, logging exports to China fuel a growing demand for classical furniture dating back to the Ming Dynasty. Conflicting demands for rosewood are often portrayed in terms of an East-West tension. Indeed, accounts of many global conservation resources, including ivory, rhino horn, tiger parts, and shark fin, fit this portrayal. In breaking with these accounts, I analyze global demands for rosewood in terms of two overlapping conservation and commodity assemblages. Both global assemblages have reterritorialized the forest of northeastern Madagascar. Via NGO offices in the United States, the conservation assemblage delineates vast tracts of forest for protection and identifies the communities that are to be its managers. Via rosewood importers in China, the commodity assemblage drives thousands of loggers into these protected forests in search of rosewood. Yet, rather than representing irreconcilable vantages, these global assemblages demonstrate a fundamental congruence. Both conservation and commodity assemblages blur global rationalities with situated cultural elements, creating the illusion of either a universal science uncorrupted by culture, or a cultural eminence uncorrupted by capitalism. Analyzing rosewood in terms of assemblage reveals not the stark contrast of an increasingly bifurcating global order, but rather an emergent space of global connectivity that complicates binary understandings of East and West, while simultaneously speaking to the reality of these geopolitical imaginaries.  相似文献   

Natural resources depletion in hill areas of Bangladesh: A review   总被引：1，自引：1，他引：0  

Shampa BISWAS  Mark E.SWANSON  Harald VACIK 《山地科学学报》2012,9(2):147-156

Hilly or mountainous terrain occupies around 12% of the area of Bangladesh.Natural resources associated with Bangladesh’s hill are forest resources,biodiversity,minerals,and agricultural crops.Natural resources have been exploited in the recent four decades due to excessive clearing of hill forest cover,resulting in loss of species richness, impacts related to increased water flow variability, increased hill slope erosion and flooding intensity, and a gradual decrease in the extent of hill area in Bangladesh.This review explores the major causes and effects of depletion of natural resources by linking drivers,pressures and the related impacts.A review has been conducted to structure the effects on the hilly areas and describe the responses to minimize them in the associated DPSIR framework.Population growth has been identified as a major driver contributing to high deforestation rates.This may negatively effect agricultural productivity and increase the frequency of serious flooding.Slash and burn cultivation also impacts the regeneration of evergreen forests,which may accelerate soil erosion. Due to this and other factors,local people are facing a deficits of natural resources(food,fodder,fuel wood and water),which exacerbates the effects of poverty. Future research should try to facilitate decision making for sustainable utilization of natural resources management in the hilly areas of Bangladesh. Additional conservation measures should be developed to increase the resilience of ecosystems at national and regional levels.  相似文献   

Transportation costs and the spatial distribution of land use in the Brazilian Amazon   总被引：1，自引：0，他引：1  

Diana Weinhold  Eustaquio Reis 《Global Environmental Change》2008,18(1):54-68

We examine the question of whether reducing transport costs in the Amazon has lead to increased land clearing. Data on land clearing, transport costs and other related variables from 1975 to 1995 is analyzed using econometric approaches that exploit the dynamic time series dimension of the data to control for possible omitted variables and endogeneity. Our results suggest that the impact of changes in transport costs on clearing depends greatly on the initial land use. Specifically, we find that in regions where a greater proportion of the land is already cleared, reducing transport costs can lessen the rate of future clearing. On the other hand, reducing transport costs through areas that have seen little human activity is more likely to increase deforestation.  相似文献   

The scale of forest transition: Amazonia and the Atlantic forests of Brazil     

Robert Walker 《Applied geography (Sevenoaks, England)》2012,32(1):12-20

This article adapts a general equilibrium model that provides a spatial solution for land use, labor allocation, and product markets in a two good economy. The adaptation, based on von Thünen, considers the multi-regional case, and solves for two regions, one industrial and the other, a newly opened agricultural frontier. The conceptual framework is considered with reference to Brazil, where forest recovery in the Atlantic Rainforest occurs simultaneously with forest losses in Amazonia. Simulation results of the theoretical model are given, demonstrating the impacts of comparative advantage in regional agriculture on the spatial system. The main theoretical interest of the article, aside from providing a formal spatial statement, is to define a distinction between aggregate forest transition (A-FT), when the area of all forests in a multi-regional system increases with the advent of trade relations, and regional forest transition (R-FT), when forest recovery is spatially constrained, and depends on forest losses elsewhere. Thus, the article addresses the role of scale in defining forest transition, and does so by representing spatial dynamics with a formal model. It also suggests that forest transition privileges one biome at the expense of others, and that a concept of landscape turnaround is more germane from a wildlands conservation perspective. The article closes with a discussion of Brazil, and how its forests in Amazonia and along the Atlantic will fare in the coming years.  相似文献   

Analyzing the agricultural transition in Mato Grosso, Brazil, using satellite-derived indices     

Damien Arvor  Margareth Meirelles  Vincent Dubreuil 《Applied geography (Sevenoaks, England)》2012,32(2):702-713

The Amazonian state of Mato Grosso is the main production area for soybeans in Brazil and contains 31.3% of the national production as of 2009. The rapid evolution of the agricultural systems in this area shows that the region is experiencing a rapid agricultural transition. In this paper, we broke down this transition process into three steps: crop expansion, agricultural intensification and ecological intensification. We used remote sensing products to develop and compute satellite-derived indices describing the main agricultural dynamics during the cropping years from 2000-2001 to 2006-2007. Our results indicated that Mato Grosso is continuing to expand its agricultural sector, with a 43% increase in the net cropped area during the study period. Although this expansion mainly occurred in the cerrado ecoregion until the early 2000s, the forest ecoregion is experiencing expansion at this time. We observed that 65% of the crop expansion in Mato Grosso from 2000 to 2006 occurred in this ecoregion. However, we did not identify this crop expansion as the major driver of deforestation in Mato Grosso because only 12.6% of the cleared areas were directly converted into croplands. Agricultural intensification also evolved rapidly, as the proportion of the net cropped area cultivated with double cropping systems harvesting two successive commercial crops (i.e., soybean and corn or soybean and cotton) increased from 6% to 30% during the study period. Finally, we found that ecological intensification occurred because the region’s farmers planted a non-commercial crop (i.e., millet or sorghum) after the soybean harvest to prevent soil erosion, improve soil quality, break pest cycles, maintain soil moisture and set the conditions for high-quality no-tillage operations. In 2006-2007, 62% of the net cropped area was permanently covered by crops during the entire rainy season. This practice allowed the farmers to diversify their production, as shown by the positive evolution of the Area Diversity Index. Future scholars can use the method proposed in this paper to improve their understanding of the forces driving the agricultural dynamics in Mato Grosso.  相似文献   

Radar remote sensing for monitoring of dynamic ecosystem processes related to biogeochemical exchanges in tropical peatlands   总被引：1，自引：0，他引：1  

Shakil Ahmad Romshoo 《Visual Geosciences》2004,9(1):9-28

Peatlands are an important multipurpose ecosystem, supporting huge quantities of biomass and peat soil carbon. A time series of Japanese Earth Resource Satellite-1 (JERS-1) L-band Synthetic Aperture Radar (SAR) data was employed to monitor two dynamic ecosystem processes; deforestation and inundation patterns. Using a change detection analysis for three images acquired during dry seasons of 1994, 1997 and 1998, we detected the deforestation that has occurred in the region due to the anthropogenic and natural causes. At a threshold of ±2 dB change in backscattering response, an area of about 98 km² of these forests was found to have been cleared during 1994–1997 for conversion to cultivatable lands. However, the agricultural crops miserably failed to grow on these cleared lands because of the adverse water and soil chemistry conditions. The deliberate draining of these lands, by laying and extension of a huge network of canals, created congenial ecological conditions for the spread of forest fires, particularly during the 1997 El Niño period. An area of 250 km² of forests was thus detected to have been destroyed by these fires between September 1997 and January 1998. These deforested lands are rapidly regenerating since their abandonment and the regenerating carbon stocks were simulated using the CENTURY ecosystem dynamics model. Furthermore, the L-band SAR was able to detect the pixel-wise seasonal and spatial inundation information for particular forest types where the transmissivity of the L-band SAR signals was quite significant. These forest types corresponded to comparatively low biomass areas. The SAR derived information about these two important dynamic processes would be useful for improving the accuracy of modelling the spatial and temporal distribution of the carbon and other trace gases in these ecosystems.Edited by D. Boyd  相似文献   

Post-deforestation soil loss from steepland hillslopes in Taranaki,New Zealand     

R. C. Derose  N. A. Trustrum  P. M. Blaschke 《地球表面变化过程与地形》1993,18(2):131-144

Soil erosion on steepland hillslopes in Taranaki, New Zealand, where landsliding is the dominant erosion form, was investigated by comparing mean regolith depths between first-order basins that have had their forest cover removed for different periods of time. Regolith depth and slope angle data were collected along 19 profile lines and 30 profile lines from steepland basins that had been deforested for 10 and 85 years, respectively. These profile lines were subdivided into a total of 236 profile segments of relatively linear slope angle and uniform regolith depth, that averaged 17·5 m in length. The depth of pre-existing regolith on post-deforestation landslide sites is estimated from a regression of regolith depth on slope angle for undisturbed (non-landslide) profile segments. Regolith depletion on landslide sites is in turn estimated by subtracting the depth of regolith on landslide sites from the estimate of pre-existing regolith depth. Regolith depletion by post-deforestation landslides, averaged over the entire length of profile lines, gives an estimate of average surface lowering. For the area deforested for 85 years, average surface lowering by post-deforestation landslides is 0·15 ± 0·04 m, and is the same as the difference in mean depth of 0·15 ± 0·11 m between this area and the area deforested for 10 years. Erosion of regolith from hillslopes by processes other than landsliding appears to be minimal. The 0·15 m average surface lowering represents a regolith depletion rate of 1·8 ± 0±5 mm yr^?1. For hillslopes steeper than 28°, where all post-deforestation landslides occur, average surface lowering is 0·20 ± 0·05 m, and the regolith depletion rate is 2±4 · 0±6 mm yr^?1. Average surface lowering is greatest at 0·23 ± 0·07 m on hillslopes steeper than 32° where most post-deforestation landslides occur. Here, the regolith depletion rate is 2·7 ± 0·8 mm yr^?1. A large-magnitude, low-frequency storm in March 1990, produced an average surface lowering of 0·041 m. There were proportionately more landslides in the area deforested for 10 years, illustrating the importance of previous erosion history of hillslopes on the spatial distribution of landslides. There were also comparatively few landslides on steeper hillslopes because previous lower magnitude storms had already removed much of the deeper regolith.  相似文献   

Numerical　Simulation　for　the　Impact　of　Deforestation　on　Climate　in　China　and　Its　Neighboring　Regions   总被引：2，自引：0，他引：2  

Song Yukuan  Chen Longxun  Dong Min 《大气科学进展》1994,11(2):212-223

ＮｕｍｅｒｉｃａｌＳｉｍｕｌａｔｉｏｎｆｏｒｔｈｅＩｍｐａｃｔｏｆＤｅｆｏｒｅｓｔａｔｉｏｎ　ｏｎ　Ｃｌｉｍａｔｅ　ｉｎ　ＣｈｉｎａａｎｄＩｔｓＮｅｉｇｈｂｏｒｉｎｇ　ＲｅｇｉｏｎｓＳｏｎｇＹｕｋｕａｎ（宋玉宽）；ＣｈｅｎＬｏｎｇｘｕｎ（陈隆勋）ａｎ...  相似文献   

Changing sedimentation patterns due to historical land-use change in Frenchman’s Bay,Pickering, Canada: evidence from high-resolution textural analysis     

P. J. van Hengstum  E. G. Reinhardt  J. I. Boyce  C. Clark 《Journal of Paleolimnology》2007,37(4):603-618

This study examines the anthropogenic alteration of sedimentation in Frenchman’s Bay in Lake Ontario, using high-resolution particle size analysis in two 200 cm cores. Lithofacies were determined using the particle size data of both the terrigenous sediment and terrigenous sediment + diatom fractions. Terrigenous particle size data from the centre of the lagoon provided the most representative record of anthropogenic impacts. Three distinctive lithofacies were recognized: (1) a Natural Wetland (NW) lithofacies (106–200 cm) had an average mean particle size of 49.4 μm, a mode of 29.4 μm and an average standard deviation of 119.1 μm; (2) an Agricultural and Deforestation (AD) lithofacies (40–105 cm) had a statistically significant lower average mean (30.8 μm), mode (13.5 μm), and standard deviation (48.5) μm; (3) an Urbanized (U) lithofacies (0–40 cm) showed a continued trend towards smaller particle sizes with an average mean of 21.2 μm, a mode of 9.4 μm, and an average standard deviation of 32.7 μm. The lithofacies correlated with previously identified trends in thecamoebian biofacies and magnetic susceptibility data showing post-colonial lagoon eutrophication and increased overland soil erosion. The up-core trend towards finer and less variable particle sizes is attributed to erosion of fine-grained watershed sediments (glacial Lake Iroquois silts and clay) during land-clearance and modification of natural drainage patterns. The influx of silts and clays into the lagoon is also recorded by increased sediment accumulation rates and a reduction in seasonal sediment variability in the wetland. Based on the ²¹⁰Pb dates, sedimentation rates increased at 1850 ±56 AD (AD lithofacies) and suggest an exponentially increasing trend in accumulation rates. Increasing sedimentation rates can be attributed to the progressive loss of native vegetation and intensified erosion of Lake Iroquois deposits via stream and hillslope erosion. Ecologically, the increased input of fine-grained sediments into the wetland has resulted in reduced water clarity and has altered the wetland substrate contributing to wetland loss in Frenchman’s Bay.  相似文献   

Land cover changes in the Brazilian Cerrado and Caatinga biomes from 1990 to 2010 based on a systematic remote sensing sampling approach     

《Applied geography (Sevenoaks, England)》2015

The main objective of our study was to provide consistent information on land cover changes between the years 1990 and 2010 for the Cerrado and Caatinga Brazilian seasonal biomes. These areas have been overlooked in terms of land cover change assessment if compared with efforts in monitoring the Amazon rain forest. For each of the target years (1990, 2000 and 2010) land cover information was obtained through an object-based classification approach for 243 sample units (10  km × 10  km size), using (E)TM Landsat images systematically located at each full degree confluence of latitude and longitude. The images were automatically pre-processed, segmented and labelled according to the following legend: Tree Cover (TC), Tree Cover Mosaic (TCM), Other Wooded Land (OWL), Other Land Cover (OLC) and Water (W). Our results indicate the Cerrado and Caatinga biomes lost (gross loss) respectively 265,595 km² and 89,656 km² of natural vegetation (TC + OWL) between 1990 and 2010. In the same period, these areas also experienced gain of TC and OWL. By 2010, the percentage of natural vegetation cover remaining in the Cerrado was 47% and in the Caatinga 63%. The annual (net) rate of natural vegetation cover loss in the Cerrado slowed down from −0.79% yr⁻¹ to −0.44% yr⁻¹ from the 1990s to the 2000s, while in the Caatinga for the same periods the rate increased from −0.19% yr⁻¹ to −0.44% yr⁻¹. In summary, these Brazilian biomes experienced both loss and gains of Tree Cover and Other Wooded Land; however a continued net loss of natural vegetation was observed for both biomes between 1990 and 2010. The average annual rate of change in this period was higher in the Cerrado (−0.6% yr⁻¹) than in the Caatinga (−0.3% yr⁻¹).  相似文献