Vast grasslands are found in the walnut-fruit forest region of southern Kyrgyzstan,Middle Asia.Located above the worldwide unique walnutfruit forests and used for grazing,they play a pivotal role in the mixed mountain...Vast grasslands are found in the walnut-fruit forest region of southern Kyrgyzstan,Middle Asia.Located above the worldwide unique walnutfruit forests and used for grazing,they play a pivotal role in the mixed mountain agriculture of local farmers.Accordingly,these pastures are subject to an increasing utilization pressure reflecting the changing political and social conditions in the transformation process from a Soviet republic to an independent state.A first detailed analysis of mountain pasture vegetation in the Ferghana Range answers the following questions:What are the main plant community types among Kyrgyzstan's mountain pastures? What are the main environmental gradients that shape their species composition? Which phytogeographical distribution types are predominant? How does grazing affect community composition and species richness in these grasslands? Species composition was classified by cluster analysis;underlying environmental gradients were explored using DCA.A dataset of 395 relevés was used for classification,and a subset of 79 relevés was used in a DCA to analyze the correlation between vegetation,environment,and grazing impact.The investigated pastures were classified into four distinctive plant communities.The site factors altitude,heat load,inclination and grazing impact were found to be the major determinants of the vegetation pattern.A significant overlap between floristic composition and structural and spatial properties was shown.The majority of the species pool consisted of Middle Asian endemics and Eurosiberian species.However,disturbance-tolerant species played a significant role with respect to species composition and coverage of the herbaceous layer in vast areas of southern Kyrgyzstan's mountain pastures.In general,an intense grazing impact is clearly reflected by both species composition and structural variables of plant communities.The highly diverse and unique ecosystem is modified by an increasing utilization pressure.In order to maintain vital processes and functioning of this valuable ecosystem-in both economical and ecological terms-,it is indispensable to adopt appropriate pasture management strategies.展开更多
Transhumant pastoralism is an important activity in southern Morocco. Migration pattern of transhumant pastoralists can be affected by physical factors (e.g. droughts and diseases) or socioeconomic factors (e.g. schoo...Transhumant pastoralism is an important activity in southern Morocco. Migration pattern of transhumant pastoralists can be affected by physical factors (e.g. droughts and diseases) or socioeconomic factors (e.g. schooling options for children and migration costs). We studied the spatio-temporal rangeland usage of the three tribes Ait Mgoun, Ait Zekri, and Ait Toumert in the south-central Atlas region with a two-fold approach. First, we tracked the migration movements of one representative transhumant herd using the Advanced Research and Global Observation Satellite (ARGOS) collars, which record coordinates from satellite signals. Second, we interviewed herders to obtain information about general grazing practices of the respective tribe and to gain more direct information on motivations underlying decisions. For each tribe we observed small-, medium- and large-scale movements. We found that the most important drivers of migration decisions were seasonal fodder availability and weather conditions in combination with herd-specific risk and cost assessment, as well as personal factors. In conclusion, general migration patterns vary in time, both between and within the tribes, but according to a regulatory framework. Moreover, it appears that both the customary rules and its flexible adaptation to physical constraints are generally beneficial in terms of conservation of the arid and semiarid rangeland resources.展开更多
Carbon budget changes were measured on a farm near Robinson, Texas, where land originally tilled for hay production was abandoned over time periods of 10, 20, and 35 years followed by succession of prairie and forest ...Carbon budget changes were measured on a farm near Robinson, Texas, where land originally tilled for hay production was abandoned over time periods of 10, 20, and 35 years followed by succession of prairie and forest vegetation. Woody biomass accumulation increased following abandonment from 0.14 kg C m2 yr~ during forest initiation to 0.57 kg C m2 yr-1 of the mature forest Soil carbon was highest in the tilled field ( 15.77 kg C m2) with lowest in the grassland ( 11.66 kg C m-2). Soil nitrogen was highest in the tilled field (0.55 kg N ms) and lowest in the forest transition (0.38 kg N m2). Soil C:N ratios were highest in the forest transition (C:N=36) and lowest in the grassland (C:N=22). Soil respiration was constant across the site with an annual average value of 1.46 kg CO2-C m-2 yr-. Results show that land in this region may be a source of carbon for several decades following abandonment due to enhanced soil carbon emissions as a function of nutrient input shifts.展开更多
Rangelands occupy more than 80% of the agricultural land in Kyrgyzstan. At least 30% of Kyrgyz pasture areas are considered to be subject to vegetation and soil degradation. Since animal husbandry is the economic basi...Rangelands occupy more than 80% of the agricultural land in Kyrgyzstan. At least 30% of Kyrgyz pasture areas are considered to be subject to vegetation and soil degradation. Since animal husbandry is the economic basis to sustain people's livelihoods, rangeland degradation presents a threat for the majority of the population. We present for the first time an ecological assessment of different pasture types in a remote area of the Naryn Oblast, using vegetation and softs as indicators of rangeland conditions. We analysed the current degree of utilization (grazing pressure), the amount of biomass, soil samples, and vegetation data, using cluster analysis as well as ordination techniques. Winter pastures (kyshtoo) are characterized by higher pH values (average of 7.27) and lower organic matter contents (average of 12.83%) compared to summer pastures (dzailoo) with average pH values of 6.03 and average organic matter contents of 21.05%. Additionally, summer pastures show higher above- ground biomass, and higher species richness and diversity. Our results support the hypothesis that winter pastures, which are located near settlements, suffer from over-utilisation, while the more distant summer pastures are subjected to much lower grazing pressure,展开更多
The paper describes the capabilities and opportunities of Remote Sensing and GIS technologies for monitoring the rangeland vegetation and its dynamics under different type of factors. Potential of satellite data of La...The paper describes the capabilities and opportunities of Remote Sensing and GIS technologies for monitoring the rangeland vegetation and its dynamics under different type of factors. Potential of satellite data of Landsat 7 Enhanced Thematic Mapper Plus (ETM+) Imagery for monitoring the rangeland condition of Karnabchul semi desert was exemined. The paper presents the first stage of a method for vegetation assessment of rangelands based on spectral vegetation indices such as Normalized Difference Vegetation Index (NDVI) derived from remotely sensed data. Initial results of the research showed the Landsat satellite images can provide relevant information about current condition of rangeland vegetation. It is recommended to conduct further studies using remotely sensed data for improvement of the rangeland monitoring methods.展开更多
Livestock sector occupies a very crucial position in the economy of Pakistan. The sector is equally important in irrigation as well as in arid/rain fed areas. Based on the valid reasons and available data, some scient...Livestock sector occupies a very crucial position in the economy of Pakistan. The sector is equally important in irrigation as well as in arid/rain fed areas. Based on the valid reasons and available data, some scientists believe that livestock can strengthen and boost-up the economy of the rain fed/arid lands like Pothowar plateau where other enterprises like crops do not flourish and witness success due to drought and uncertain weather conditions. In this article, an attempt has been made to establish the role of livestock rearing in both the high and low potential areas. Their role in the overall economy of the country has been highlighted. Also many constraints in livestock business have been identified. The livestock sector in Pakistan has tremendous potential for growth. Therefore, a workable strategy for the promotion of the livestock has been outlined to uplift the rural economy and improve the socio-economic conditions of the rural dweller of the country.展开更多
Goat satisfying energy requirements of goat are determined by anatomical body and browse leaves. In High Bassin zone of Mandrare in Southern Madagascar, sampling area of 400 m^2 has been monitored to analysis floristi...Goat satisfying energy requirements of goat are determined by anatomical body and browse leaves. In High Bassin zone of Mandrare in Southern Madagascar, sampling area of 400 m^2 has been monitored to analysis floristic diversity and Shannon-Weaver index and to establish rangeland typology. With one ram, two castrated goats and three ewes, foraging behaviour, bite rate and forage nutritive value were analyzed in native pastureland during six days at two browsing periods. As results, four pastureland groups were classified with dominant shrubs plants Acacia farnesiana, Poupartia caffra, Kigelianthe madagascariensis and Rhigozum madagascariense. Rangelands sites have presented lower heterogeneity with floristic density (236-658 plants per hectare), Shannon-Weaver index (0.28-0.95), maximum diversity (1.04 ± 0.07) with P 〈 0.05. Most of 42 identified fodder plants presented significant difference (P 〈 0.05) and higher nutritive value (35-54% Dry Matter or DM); mineral matter (70-162 g·kg DM^-1); Crude Protein (124-175 g·kg DM^-1); Crude Fibre (203-376 g·kg DM^-1); Neutral Detergent Fiber (388-548 g·kg DM^-1) and gross energy (3617-4464 kcal·kg DM^-1). Acaciafarnesiana rangeland was overgrazed with 4.00 to 9.00 bites·mn^-1. In fact, relationships between phytosociology, nutritional parameters and foraging behaviour have been analyzed to improve with autochthonous plants and to manage rangeland in semi arid environment.展开更多
The Holy Quran (1982) is the Holy Book of the Moslems and the most understandable aspect of its eloquence. One of the most interesting aspects found in different languages is the use of implicatures or implied meani...The Holy Quran (1982) is the Holy Book of the Moslems and the most understandable aspect of its eloquence. One of the most interesting aspects found in different languages is the use of implicatures or implied meaning. How and why such implicatures are generated and are discussed in pragmatics? In this study, a list of conversations (direct and indirect) from "Surah Livestock" ("A1-An'am"), the sixth Chapter of the Holy Quran, and the implicatures implied in the conversations are analyzed through a pragmatic theory: CP (Cooperative Principle). The present study shows that in most cases, the non-observance of Grice's (1975) maxims is found in the maxim of Quantity and the least in Manner. Grice's CP and its contributory maxims have not been observed in the "Surah Livestock" in this study. All maxims of Grice have been flouted in This Surah (1982) and there is no difference among Gricean maxims as far as flouting in the Surah is concerned.展开更多
The increase of probability and depth of weather anomalies, which is important characteristic of climate change process, leads to higher risk of loss of perennial grasses forage yield, rise of price volatility on fora...The increase of probability and depth of weather anomalies, which is important characteristic of climate change process, leads to higher risk of loss of perennial grasses forage yield, rise of price volatility on forage grain market. Increase of sustainability of dairy production supposes development of adapted to new weather conditions technologies of forage production, which are characterized by different investment and current costs. It generates a need of economic evaluation and comparative analysis of technologies taking into account climate change forecast and need of sustainable forage production guarantee. Purpose of the research project is the development of approaches to assessing adaptive technologies in forage production, increasing of dairy farming sustainability to changes in the external environment, including climate change. We assessed changes in forage production technologies in the Leningrad region of Russia, analyzed the implications of these changes for production and financial performance of dairy farming, proposed and tested methods for determination of the optimum harvesting time of perennial grasses. Special attention is paid to the long-term effects of changing the structure of cows' diet--shortening the productive use of animals, which reduces the efficiency of dairy herd use and limits the possibility of expanded reproduction. The primary method of the study is the analysis of milk production statistics in the Leningrad region and the Russian Federation. As a result of the study, the necessity to improve the production and investment planning quality, as well as the use of forecasts during planning of dairy production, is grounded.展开更多
The area along the Grear Wall in northern Shaanxi between the Loess Plateau and the Ordos Desert is one of the major agrarian-pastoral regions of northwest China. Historically, the land was fought over by the nomadic ...The area along the Grear Wall in northern Shaanxi between the Loess Plateau and the Ordos Desert is one of the major agrarian-pastoral regions of northwest China. Historically, the land was fought over by the nomadic and the agrarian peoples of the region. The Yansui section of the Ming Great Wall and thirty-nine fortified encampments along it were built during fighting between the Mongols and the Han people. As all of them were located along communication lines vital to economic development, they played an important role in politics, the economy and transport over three hundred years of Ming and Qing rule. However, they fell into disuse in the late Qing and the Republican period and are now in ruins. The main reason underlying their decline was that the sites had been chosen for their defensive value, so the subsequent northern expansion of China’s borders and structural changes in the border economy hastened their decline. Thus the rise and fall of these fortified towns at the intersection of the agrarian and the pastoral regions was closely related to imperial political and military activity and was in line with ethnic and tribal movements and migrations and the evolution of civilizations. In sum, the reasons behind the demise of these fortified towns and camps were highly complex and usually involved multiple factors.展开更多
The pollution of soils by heavy metals has dramatically increased in recent decades. Phytoextraction is a technology that extracts elements from polluted soils using hyperaccumulator plants. The selection of appropria...The pollution of soils by heavy metals has dramatically increased in recent decades. Phytoextraction is a technology that extracts elements from polluted soils using hyperaccumulator plants. The selection of appropriate plant materials is an important factor for successful phytoextraction in field. A field study was conducted to compare the efficiency of six high-biomass forage species in their phytoextraction of heavy metals(Cd, Pb, and Zn) from contaminated soil under two harvesting strategies(double harvesting or single harvesting). Among the tested plants, amaranth accumulated the greatest amounts of Cd and Zn, whereas Rumex K^(-1) had the highest amount of Pb in the shoot under both double and single harvesting. Furthermore, double harvesting significantly increased the shoot biomass of amaranth, sweet sorghum and sudangrass and resulted in higher heavy metal contents in the shoot. Under double harvesting, the total amounts of extracted Cd, Pb and Zn(i.e., in the first plus second crops) for amaranth were 945, 2 650 and 12 400 g ha^(-1), respectively, the highest recorded among the six plant species. The present results indicate that amaranth has great potential for the phytoextraction of Cd from contaminated soils. In addition, the double harvesting method is likely to increase phytoextraction efficiency in practice.展开更多
基金the joint project "The Impact of the Transformation Process on Human-Environmental Interactions in Southern Kyrgyzstan" supported by the Volkswagen Foundation
文摘Vast grasslands are found in the walnut-fruit forest region of southern Kyrgyzstan,Middle Asia.Located above the worldwide unique walnutfruit forests and used for grazing,they play a pivotal role in the mixed mountain agriculture of local farmers.Accordingly,these pastures are subject to an increasing utilization pressure reflecting the changing political and social conditions in the transformation process from a Soviet republic to an independent state.A first detailed analysis of mountain pasture vegetation in the Ferghana Range answers the following questions:What are the main plant community types among Kyrgyzstan's mountain pastures? What are the main environmental gradients that shape their species composition? Which phytogeographical distribution types are predominant? How does grazing affect community composition and species richness in these grasslands? Species composition was classified by cluster analysis;underlying environmental gradients were explored using DCA.A dataset of 395 relevés was used for classification,and a subset of 79 relevés was used in a DCA to analyze the correlation between vegetation,environment,and grazing impact.The investigated pastures were classified into four distinctive plant communities.The site factors altitude,heat load,inclination and grazing impact were found to be the major determinants of the vegetation pattern.A significant overlap between floristic composition and structural and spatial properties was shown.The majority of the species pool consisted of Middle Asian endemics and Eurosiberian species.However,disturbance-tolerant species played a significant role with respect to species composition and coverage of the herbaceous layer in vast areas of southern Kyrgyzstan's mountain pastures.In general,an intense grazing impact is clearly reflected by both species composition and structural variables of plant communities.The highly diverse and unique ecosystem is modified by an increasing utilization pressure.In order to maintain vital processes and functioning of this valuable ecosystem-in both economical and ecological terms-,it is indispensable to adopt appropriate pasture management strategies.
基金funded by the German Federal Ministry of Research and Education (Grant no. 01 LC 0601A)
文摘Transhumant pastoralism is an important activity in southern Morocco. Migration pattern of transhumant pastoralists can be affected by physical factors (e.g. droughts and diseases) or socioeconomic factors (e.g. schooling options for children and migration costs). We studied the spatio-temporal rangeland usage of the three tribes Ait Mgoun, Ait Zekri, and Ait Toumert in the south-central Atlas region with a two-fold approach. First, we tracked the migration movements of one representative transhumant herd using the Advanced Research and Global Observation Satellite (ARGOS) collars, which record coordinates from satellite signals. Second, we interviewed herders to obtain information about general grazing practices of the respective tribe and to gain more direct information on motivations underlying decisions. For each tribe we observed small-, medium- and large-scale movements. We found that the most important drivers of migration decisions were seasonal fodder availability and weather conditions in combination with herd-specific risk and cost assessment, as well as personal factors. In conclusion, general migration patterns vary in time, both between and within the tribes, but according to a regulatory framework. Moreover, it appears that both the customary rules and its flexible adaptation to physical constraints are generally beneficial in terms of conservation of the arid and semiarid rangeland resources.
文摘Carbon budget changes were measured on a farm near Robinson, Texas, where land originally tilled for hay production was abandoned over time periods of 10, 20, and 35 years followed by succession of prairie and forest vegetation. Woody biomass accumulation increased following abandonment from 0.14 kg C m2 yr~ during forest initiation to 0.57 kg C m2 yr-1 of the mature forest Soil carbon was highest in the tilled field ( 15.77 kg C m2) with lowest in the grassland ( 11.66 kg C m-2). Soil nitrogen was highest in the tilled field (0.55 kg N ms) and lowest in the forest transition (0.38 kg N m2). Soil C:N ratios were highest in the forest transition (C:N=36) and lowest in the grassland (C:N=22). Soil respiration was constant across the site with an annual average value of 1.46 kg CO2-C m-2 yr-. Results show that land in this region may be a source of carbon for several decades following abandonment due to enhanced soil carbon emissions as a function of nutrient input shifts.
基金funded by BMBF(Bundesministerium für Bildung und Forschung,Germany)(Ff E_IB-074)the context of the joint project TRANSPAST
文摘Rangelands occupy more than 80% of the agricultural land in Kyrgyzstan. At least 30% of Kyrgyz pasture areas are considered to be subject to vegetation and soil degradation. Since animal husbandry is the economic basis to sustain people's livelihoods, rangeland degradation presents a threat for the majority of the population. We present for the first time an ecological assessment of different pasture types in a remote area of the Naryn Oblast, using vegetation and softs as indicators of rangeland conditions. We analysed the current degree of utilization (grazing pressure), the amount of biomass, soil samples, and vegetation data, using cluster analysis as well as ordination techniques. Winter pastures (kyshtoo) are characterized by higher pH values (average of 7.27) and lower organic matter contents (average of 12.83%) compared to summer pastures (dzailoo) with average pH values of 6.03 and average organic matter contents of 21.05%. Additionally, summer pastures show higher above- ground biomass, and higher species richness and diversity. Our results support the hypothesis that winter pastures, which are located near settlements, suffer from over-utilisation, while the more distant summer pastures are subjected to much lower grazing pressure,
文摘The paper describes the capabilities and opportunities of Remote Sensing and GIS technologies for monitoring the rangeland vegetation and its dynamics under different type of factors. Potential of satellite data of Landsat 7 Enhanced Thematic Mapper Plus (ETM+) Imagery for monitoring the rangeland condition of Karnabchul semi desert was exemined. The paper presents the first stage of a method for vegetation assessment of rangelands based on spectral vegetation indices such as Normalized Difference Vegetation Index (NDVI) derived from remotely sensed data. Initial results of the research showed the Landsat satellite images can provide relevant information about current condition of rangeland vegetation. It is recommended to conduct further studies using remotely sensed data for improvement of the rangeland monitoring methods.
文摘Livestock sector occupies a very crucial position in the economy of Pakistan. The sector is equally important in irrigation as well as in arid/rain fed areas. Based on the valid reasons and available data, some scientists believe that livestock can strengthen and boost-up the economy of the rain fed/arid lands like Pothowar plateau where other enterprises like crops do not flourish and witness success due to drought and uncertain weather conditions. In this article, an attempt has been made to establish the role of livestock rearing in both the high and low potential areas. Their role in the overall economy of the country has been highlighted. Also many constraints in livestock business have been identified. The livestock sector in Pakistan has tremendous potential for growth. Therefore, a workable strategy for the promotion of the livestock has been outlined to uplift the rural economy and improve the socio-economic conditions of the rural dweller of the country.
文摘Goat satisfying energy requirements of goat are determined by anatomical body and browse leaves. In High Bassin zone of Mandrare in Southern Madagascar, sampling area of 400 m^2 has been monitored to analysis floristic diversity and Shannon-Weaver index and to establish rangeland typology. With one ram, two castrated goats and three ewes, foraging behaviour, bite rate and forage nutritive value were analyzed in native pastureland during six days at two browsing periods. As results, four pastureland groups were classified with dominant shrubs plants Acacia farnesiana, Poupartia caffra, Kigelianthe madagascariensis and Rhigozum madagascariense. Rangelands sites have presented lower heterogeneity with floristic density (236-658 plants per hectare), Shannon-Weaver index (0.28-0.95), maximum diversity (1.04 ± 0.07) with P 〈 0.05. Most of 42 identified fodder plants presented significant difference (P 〈 0.05) and higher nutritive value (35-54% Dry Matter or DM); mineral matter (70-162 g·kg DM^-1); Crude Protein (124-175 g·kg DM^-1); Crude Fibre (203-376 g·kg DM^-1); Neutral Detergent Fiber (388-548 g·kg DM^-1) and gross energy (3617-4464 kcal·kg DM^-1). Acaciafarnesiana rangeland was overgrazed with 4.00 to 9.00 bites·mn^-1. In fact, relationships between phytosociology, nutritional parameters and foraging behaviour have been analyzed to improve with autochthonous plants and to manage rangeland in semi arid environment.
文摘The Holy Quran (1982) is the Holy Book of the Moslems and the most understandable aspect of its eloquence. One of the most interesting aspects found in different languages is the use of implicatures or implied meaning. How and why such implicatures are generated and are discussed in pragmatics? In this study, a list of conversations (direct and indirect) from "Surah Livestock" ("A1-An'am"), the sixth Chapter of the Holy Quran, and the implicatures implied in the conversations are analyzed through a pragmatic theory: CP (Cooperative Principle). The present study shows that in most cases, the non-observance of Grice's (1975) maxims is found in the maxim of Quantity and the least in Manner. Grice's CP and its contributory maxims have not been observed in the "Surah Livestock" in this study. All maxims of Grice have been flouted in This Surah (1982) and there is no difference among Gricean maxims as far as flouting in the Surah is concerned.
文摘The increase of probability and depth of weather anomalies, which is important characteristic of climate change process, leads to higher risk of loss of perennial grasses forage yield, rise of price volatility on forage grain market. Increase of sustainability of dairy production supposes development of adapted to new weather conditions technologies of forage production, which are characterized by different investment and current costs. It generates a need of economic evaluation and comparative analysis of technologies taking into account climate change forecast and need of sustainable forage production guarantee. Purpose of the research project is the development of approaches to assessing adaptive technologies in forage production, increasing of dairy farming sustainability to changes in the external environment, including climate change. We assessed changes in forage production technologies in the Leningrad region of Russia, analyzed the implications of these changes for production and financial performance of dairy farming, proposed and tested methods for determination of the optimum harvesting time of perennial grasses. Special attention is paid to the long-term effects of changing the structure of cows' diet--shortening the productive use of animals, which reduces the efficiency of dairy herd use and limits the possibility of expanded reproduction. The primary method of the study is the analysis of milk production statistics in the Leningrad region and the Russian Federation. As a result of the study, the necessity to improve the production and investment planning quality, as well as the use of forecasts during planning of dairy production, is grounded.
文摘The area along the Grear Wall in northern Shaanxi between the Loess Plateau and the Ordos Desert is one of the major agrarian-pastoral regions of northwest China. Historically, the land was fought over by the nomadic and the agrarian peoples of the region. The Yansui section of the Ming Great Wall and thirty-nine fortified encampments along it were built during fighting between the Mongols and the Han people. As all of them were located along communication lines vital to economic development, they played an important role in politics, the economy and transport over three hundred years of Ming and Qing rule. However, they fell into disuse in the late Qing and the Republican period and are now in ruins. The main reason underlying their decline was that the sites had been chosen for their defensive value, so the subsequent northern expansion of China’s borders and structural changes in the border economy hastened their decline. Thus the rise and fall of these fortified towns at the intersection of the agrarian and the pastoral regions was closely related to imperial political and military activity and was in line with ethnic and tribal movements and migrations and the evolution of civilizations. In sum, the reasons behind the demise of these fortified towns and camps were highly complex and usually involved multiple factors.
基金supported by the National Natural Science Foundation of China (No. 41501340)the Zhejiang Provincial Natural Science Foundation of China (No. LQ14D010002)
文摘The pollution of soils by heavy metals has dramatically increased in recent decades. Phytoextraction is a technology that extracts elements from polluted soils using hyperaccumulator plants. The selection of appropriate plant materials is an important factor for successful phytoextraction in field. A field study was conducted to compare the efficiency of six high-biomass forage species in their phytoextraction of heavy metals(Cd, Pb, and Zn) from contaminated soil under two harvesting strategies(double harvesting or single harvesting). Among the tested plants, amaranth accumulated the greatest amounts of Cd and Zn, whereas Rumex K^(-1) had the highest amount of Pb in the shoot under both double and single harvesting. Furthermore, double harvesting significantly increased the shoot biomass of amaranth, sweet sorghum and sudangrass and resulted in higher heavy metal contents in the shoot. Under double harvesting, the total amounts of extracted Cd, Pb and Zn(i.e., in the first plus second crops) for amaranth were 945, 2 650 and 12 400 g ha^(-1), respectively, the highest recorded among the six plant species. The present results indicate that amaranth has great potential for the phytoextraction of Cd from contaminated soils. In addition, the double harvesting method is likely to increase phytoextraction efficiency in practice.