The aim was to further research soil erosion characteristics and accurately predict soil erosion amount in karst areas. Based on field surveys and research achievements available, yellow soils, which are widely distri...The aim was to further research soil erosion characteristics and accurately predict soil erosion amount in karst areas. Based on field surveys and research achievements available, yellow soils, which are widely distributed, were chosen as test soil samples and slope, rain intensity, vegetation coverage and bare-rock ratio were taken as soil erosion factors. Artificial rain simulation instruments （needle-type） were made use of to simulate correlation of rain intensity, vegetation coverage, and bare-rock ratio with soil erosion quantity. Furthermore, multiple-factor linear regression analysis, stepwise regression analysis and multiple-factor non-linear regression analy- sis were made to establish a multiple-factor formula of soil erosion modulus with dif- ferent slopes and select regression models with high correlation coefficients. The re- sults show that a non-linear regression model reached extremely significant level or significant level （0.692〈FF〈0.988） and linear regression model achieved significant lev- el （0.523〈FF〈0.634）. The effects of erosion modulus changed from decreasing to in- creasing and the erosion factors from high to low were rain intensity, vegetation cov- erage and bare-rock ratio when slope gradient was at 6~, 16~, 26~ and 36~. The mod- el is of high accuracy for predicting gentle slope and abtupt slope, which reveals correlation of erosion modulus with erosion factors in karst areas.展开更多
Characteristics and distributions of humic acid(HA) and soil organic matter(SOM) in a yellow soil profile and a limestone soil profile of the southwest China Karst area were systematically investigated to reveal their...Characteristics and distributions of humic acid(HA) and soil organic matter(SOM) in a yellow soil profile and a limestone soil profile of the southwest China Karst area were systematically investigated to reveal their evolutions in different soils of the study area. The results showed that characteristics and distribution of SOM along the two soil profiles were notably different. Total organic carbon(TOC) contents of soil samples decreased just slightly along the limestone soil profile but sharply along the yellow soil profile. TOCs of the limestone soils were significantly higher than those of the corresponding yellow soils, and C/N ratios of SOMs showed a similar variation trend to that of TOCs, indicating that SOM can be better conserved in the limestone soil than in the yellow soil. The soil humic acids were exhaustively extracted and further fractionated according to their apparent molecular weights using ultrafiltration techniques to explore underlying conservation mechanisms. The result showed that C/N ratios of HAs from different limestone soil layers were relatively stable and that large molecular HA fractions predominated the bulk HA of the top soil, indicating that HA in the limestone profile was protected while bio and chemical degradations were retarded. Combined with organic elements contents and mineral contents of two soils, weconcluded that high calcium contents in limestone soils may play a key role in SOM conservation by forming complexation compounds with HAs or/and enclosing SOMs with hypergene CaCO_3 precipitation.展开更多
The Karst of Southwest China is a typical representative of poverty stricken region with impoverishment-degradation spiral. To essentially break away from this vicious circle, the local ecology, economy and society s...The Karst of Southwest China is a typical representative of poverty stricken region with impoverishment-degradation spiral. To essentially break away from this vicious circle, the local ecology, economy and society should be rehabilitated, and hence to strengthen the self-development capacity building of the localities. Two considerations are stressed in this article: (1) Poverty alleviation is a system project with great complexities. Any single approach is difficult to success and integrated measures should be taken. (2) Some typical and feasible areas should be selected to demonstrate the project of poverty alleviation and ecological, socio-economic reconstruction. Then, they can be used as a model to promote the sustainable development of the whole region. Based upon these ideals, a project entitled “Reversal of Impoverishment-Degradation Spiral in the Karst of Southwest China' was proposed and has been listed in 《Priority Programme for China's Agenda 21》.展开更多
The serious degradation of the ecological environment and the rapid expansion of stone desert have had a serious effect on the economic development of karst and rock-naked mountain areas in Southwest China. Moreover, ...The serious degradation of the ecological environment and the rapid expansion of stone desert have had a serious effect on the economic development of karst and rock-naked mountain areas in Southwest China. Moreover, these areas are still at the initial stage of industrialization, characterized by a greater significance of agriculture to the economy, face sharp contradictions among the population, the arable land and resources, and are suffering because of a shortage of investment. On the basis of this current situation, three recommendations are made in this article: "coordinating the relations among grain, ecology, population and economic development", "increasing the input of science and technology", and "adopting policies consistent with social equity in areas of poverty".展开更多
【目的】全球变暖背景下,喀斯特地貌广布的西南地区可能面临石漠化加剧的风险,对该区域石漠化演变历史的重建具有重要意义。【方法】通过采自贵州省黔西县黑洞一支石笋(HD12)的29个230Th年龄和954个δ^(13)C数据,重建了该地区过去4 750...【目的】全球变暖背景下,喀斯特地貌广布的西南地区可能面临石漠化加剧的风险,对该区域石漠化演变历史的重建具有重要意义。【方法】通过采自贵州省黔西县黑洞一支石笋(HD12)的29个230Th年龄和954个δ^(13)C数据,重建了该地区过去4 750年的生态环境演变历史。【结果与结论】发现在4 322~3 526 a B.P.以及803~82 a B.P.时段存在两个显著的δ^(13)C正偏移,说明这两个时段洞穴上方的生态环境出现了恶化。HD12石笋δ^(13)C记录在约803 a B.P.的显著偏正持续了约290 a,其振幅达4.2‰,指示了该区域石漠化的扩张过程。这一时期西南地区多个洞穴石笋δ^(13)C值的一致偏正特征,可能指示了宋末靖康事件(823 a B.P.)后,人口的大量迁入和气候的干旱化导致了该区域石漠化的扩张。HD12石笋δ^(13)C值在4 322~3 526 a B.P.时期的偏正,振幅达4.9‰,其中4 322~3 977 a B.P.偏正过程对应于北半球4.2 ka事件,而3 777~3 526 a B.P.的偏正对应3.7 ka事件,两个时期的干旱事件在西南地区的多个石笋与湖泊记录中均有体现,说明在此期间,亚洲夏季风减弱,降水减少可能引起了该区域植被覆盖度大幅降低和土壤严重退化。展开更多
As a consequence of increased population growth and environmental degradation, a particular type of population mobility-environmental migration-has emerged in the Third World. In this paper environmental migration is ...As a consequence of increased population growth and environmental degradation, a particular type of population mobility-environmental migration-has emerged in the Third World. In this paper environmental migration is defined and previous practices in some developing countries are reviewed. A case study of the Karst Region of Southwest China is used to illustrate the phenomenon, including root causes, restrictive factors, nature of the migration, desires of migrants, strategies of response and optional policies. It is argued that a comprehensive approach to the prevention of environmentally caused displacement should be developed.展开更多
This paper focuses on migration occurrence as a result of environmental degradation and population growth. It briefly reviews previous practices in some less developed courtries and then considers the extent to which ...This paper focuses on migration occurrence as a result of environmental degradation and population growth. It briefly reviews previous practices in some less developed courtries and then considers the extent to which environmental factors have been and may be significant in initiating migration. A case study of the karst region of southwest China is used to illustrate the phenomenon, including root causes, restrictive factors, nature of the migration, desires of migrants, strategies of response and optional policies. It is argued that a comprehensive approach to the prevention of environmentally caused displacement should be developed.展开更多
The existing traditional methods of assessing the rates of soil loss have many limitations and are difficult to apply in the karst areas of Southwest China. Karst depressions comprise geomorphologically important sour...The existing traditional methods of assessing the rates of soil loss have many limitations and are difficult to apply in the karst areas of Southwest China. Karst depressions comprise geomorphologically important sources and sinks for sediments and associated pollutants, yet the sedimentology of many depressions is not well understood. In this paper, the 137Cs technique was employed to investigate recent sedimentation rates in a Chinese polygonal karst depression. The results indicated that the sediment deposition rates ranged from 0.91 to 1.97 mm?a?1 in the period from 1963 to 2007, and the average sediment deposition rate and specific deposit yield of the catchment were estimated to be 1.47 mm?a?1 and 20 t?km?2?a?1, respectively. The results obtained were consistent with the local monitoring data of runoff plots, confirming the validity of the overall approach. It was shown that soil loss rates were very low in some karst areas of Southwest China. Above all, the approach appears to offer valuable potential to study surface erosion by estimating sediment deposition rates of karst depressions, rather than the assessment of complicated soil erosion in stony soils of carbonate rock slopes. In addition, the spacial distribution of surface soil and 137Cs inventories was affected remarkably by the inhomogeneous dissolution of limestone under the soil. It may be an important phenomenon which exists widely in the karst areas and is significantly different from other places.展开更多
基金Supported by National Science and Technology Support Program in Twelfth Five-year Plan(2012BAD05B06)Special Funds for Excellent Young Scientific Talents in Guizhou[(2011)14]~~
文摘The aim was to further research soil erosion characteristics and accurately predict soil erosion amount in karst areas. Based on field surveys and research achievements available, yellow soils, which are widely distributed, were chosen as test soil samples and slope, rain intensity, vegetation coverage and bare-rock ratio were taken as soil erosion factors. Artificial rain simulation instruments （needle-type） were made use of to simulate correlation of rain intensity, vegetation coverage, and bare-rock ratio with soil erosion quantity. Furthermore, multiple-factor linear regression analysis, stepwise regression analysis and multiple-factor non-linear regression analy- sis were made to establish a multiple-factor formula of soil erosion modulus with dif- ferent slopes and select regression models with high correlation coefficients. The re- sults show that a non-linear regression model reached extremely significant level or significant level （0.692〈FF〈0.988） and linear regression model achieved significant lev- el （0.523〈FF〈0.634）. The effects of erosion modulus changed from decreasing to in- creasing and the erosion factors from high to low were rain intensity, vegetation cov- erage and bare-rock ratio when slope gradient was at 6~, 16~, 26~ and 36~. The mod- el is of high accuracy for predicting gentle slope and abtupt slope, which reveals correlation of erosion modulus with erosion factors in karst areas.
基金financial supports are from the National Major Research Program of China (2013CB956702)the Natural Science Foundation of China (41273149, 41173129)+2 种基金the Science Foundation of Guizhou (20113109)the 100-Talent Program of CASthe opening project from the state key laboratory of environmental geochemistry
文摘Characteristics and distributions of humic acid(HA) and soil organic matter(SOM) in a yellow soil profile and a limestone soil profile of the southwest China Karst area were systematically investigated to reveal their evolutions in different soils of the study area. The results showed that characteristics and distribution of SOM along the two soil profiles were notably different. Total organic carbon(TOC) contents of soil samples decreased just slightly along the limestone soil profile but sharply along the yellow soil profile. TOCs of the limestone soils were significantly higher than those of the corresponding yellow soils, and C/N ratios of SOMs showed a similar variation trend to that of TOCs, indicating that SOM can be better conserved in the limestone soil than in the yellow soil. The soil humic acids were exhaustively extracted and further fractionated according to their apparent molecular weights using ultrafiltration techniques to explore underlying conservation mechanisms. The result showed that C/N ratios of HAs from different limestone soil layers were relatively stable and that large molecular HA fractions predominated the bulk HA of the top soil, indicating that HA in the limestone profile was protected while bio and chemical degradations were retarded. Combined with organic elements contents and mineral contents of two soils, weconcluded that high calcium contents in limestone soils may play a key role in SOM conservation by forming complexation compounds with HAs or/and enclosing SOMs with hypergene CaCO_3 precipitation.
文摘The Karst of Southwest China is a typical representative of poverty stricken region with impoverishment-degradation spiral. To essentially break away from this vicious circle, the local ecology, economy and society should be rehabilitated, and hence to strengthen the self-development capacity building of the localities. Two considerations are stressed in this article: (1) Poverty alleviation is a system project with great complexities. Any single approach is difficult to success and integrated measures should be taken. (2) Some typical and feasible areas should be selected to demonstrate the project of poverty alleviation and ecological, socio-economic reconstruction. Then, they can be used as a model to promote the sustainable development of the whole region. Based upon these ideals, a project entitled “Reversal of Impoverishment-Degradation Spiral in the Karst of Southwest China' was proposed and has been listed in 《Priority Programme for China's Agenda 21》.
文摘The serious degradation of the ecological environment and the rapid expansion of stone desert have had a serious effect on the economic development of karst and rock-naked mountain areas in Southwest China. Moreover, these areas are still at the initial stage of industrialization, characterized by a greater significance of agriculture to the economy, face sharp contradictions among the population, the arable land and resources, and are suffering because of a shortage of investment. On the basis of this current situation, three recommendations are made in this article: "coordinating the relations among grain, ecology, population and economic development", "increasing the input of science and technology", and "adopting policies consistent with social equity in areas of poverty".
文摘【目的】全球变暖背景下,喀斯特地貌广布的西南地区可能面临石漠化加剧的风险,对该区域石漠化演变历史的重建具有重要意义。【方法】通过采自贵州省黔西县黑洞一支石笋(HD12)的29个230Th年龄和954个δ^(13)C数据,重建了该地区过去4 750年的生态环境演变历史。【结果与结论】发现在4 322~3 526 a B.P.以及803~82 a B.P.时段存在两个显著的δ^(13)C正偏移,说明这两个时段洞穴上方的生态环境出现了恶化。HD12石笋δ^(13)C记录在约803 a B.P.的显著偏正持续了约290 a,其振幅达4.2‰,指示了该区域石漠化的扩张过程。这一时期西南地区多个洞穴石笋δ^(13)C值的一致偏正特征,可能指示了宋末靖康事件(823 a B.P.)后,人口的大量迁入和气候的干旱化导致了该区域石漠化的扩张。HD12石笋δ^(13)C值在4 322~3 526 a B.P.时期的偏正,振幅达4.9‰,其中4 322~3 977 a B.P.偏正过程对应于北半球4.2 ka事件,而3 777~3 526 a B.P.的偏正对应3.7 ka事件,两个时期的干旱事件在西南地区的多个石笋与湖泊记录中均有体现,说明在此期间,亚洲夏季风减弱,降水减少可能引起了该区域植被覆盖度大幅降低和土壤严重退化。
文摘As a consequence of increased population growth and environmental degradation, a particular type of population mobility-environmental migration-has emerged in the Third World. In this paper environmental migration is defined and previous practices in some developing countries are reviewed. A case study of the Karst Region of Southwest China is used to illustrate the phenomenon, including root causes, restrictive factors, nature of the migration, desires of migrants, strategies of response and optional policies. It is argued that a comprehensive approach to the prevention of environmentally caused displacement should be developed.
文摘This paper focuses on migration occurrence as a result of environmental degradation and population growth. It briefly reviews previous practices in some less developed courtries and then considers the extent to which environmental factors have been and may be significant in initiating migration. A case study of the karst region of southwest China is used to illustrate the phenomenon, including root causes, restrictive factors, nature of the migration, desires of migrants, strategies of response and optional policies. It is argued that a comprehensive approach to the prevention of environmentally caused displacement should be developed.
基金supported by the National Basic Research Program of China (973 Program) (Grant No. 2006CB403200)the National Natural Science Foundation of China(Grant No. 41001162)+3 种基金Knowledge Inno-vation Project of the Chinese Academy of Sciences (Grant No. KZCX2-YW-306)Provincial Governor Foundation of GuiZhou (Grant No. 2010)Opening Fund of State Key Labo-ratory of Environmental Geochemistry(Grant No. SKLEG9008)National Key Technology R & D Program (Grant Nos. 2006BAC01A09 and 2008BAD98B07)
文摘The existing traditional methods of assessing the rates of soil loss have many limitations and are difficult to apply in the karst areas of Southwest China. Karst depressions comprise geomorphologically important sources and sinks for sediments and associated pollutants, yet the sedimentology of many depressions is not well understood. In this paper, the 137Cs technique was employed to investigate recent sedimentation rates in a Chinese polygonal karst depression. The results indicated that the sediment deposition rates ranged from 0.91 to 1.97 mm?a?1 in the period from 1963 to 2007, and the average sediment deposition rate and specific deposit yield of the catchment were estimated to be 1.47 mm?a?1 and 20 t?km?2?a?1, respectively. The results obtained were consistent with the local monitoring data of runoff plots, confirming the validity of the overall approach. It was shown that soil loss rates were very low in some karst areas of Southwest China. Above all, the approach appears to offer valuable potential to study surface erosion by estimating sediment deposition rates of karst depressions, rather than the assessment of complicated soil erosion in stony soils of carbonate rock slopes. In addition, the spacial distribution of surface soil and 137Cs inventories was affected remarkably by the inhomogeneous dissolution of limestone under the soil. It may be an important phenomenon which exists widely in the karst areas and is significantly different from other places.
