人类活动导致的大气和气候变化将极大地改变作物的生长环境,其中最大的一个变化就是大气二氧化碳(CO2)浓度的迅速上升:从工业革命前的平均270μmol/mol上升到目前的381μmol/mol,到2050年至少超过550μmol/mol。FACE(Free-air CO2 enric...人类活动导致的大气和气候变化将极大地改变作物的生长环境,其中最大的一个变化就是大气二氧化碳(CO2)浓度的迅速上升:从工业革命前的平均270μmol/mol上升到目前的381μmol/mol,到2050年至少超过550μmol/mol。FACE(Free-air CO2 enrichment,开放式空气中CO2浓度增高)试验是目前评估未来高浓度CO2对作物生长和产量实际影响的最佳方法。水稻无疑是人类最重要的食物来源,迄今为止人类利用FACE技术开展水稻响应和适应的研究已有10a(19982008年)的历史。以生长发育为主线,首次系统综述了10a水稻FACE试验在该领域的研究成果,总结了FACE情形下高浓度CO2(模拟本世纪中叶大气CO2浓度)对主要供试水稻品种(小区面积大于4m2)光合作用、生育进程、地上部生长、地下部生长、物质分配、籽粒灌浆、产量构成以及倒伏性状等影响的研究进展,比较了FACE与非FACE研究之间以及中国和日本FACE研究(世界上唯一的两个大型水稻FACE研究)之间的异同点。根据研究进展以及当前的技术水平,文章最后提出了该领域的3个优先课题:(1)FACE情形下杂交稻生产力响应高于预期的生物学机制;(2)FACE情形下CO2与主要栽培措施的互作效应;(3)FACE情形下CO2与主要空气污染物臭氧的互作效应。这些响应的机理性解析将有助于从根本上减少人类预测未来粮食安全的不确定性,进而更加有效地制订出应对全球变化的适应策略。展开更多
To feed an increasing population, large amounts of chemical nitrogen fertilizer have been used to produce much of our food, feed and fiber thereby increasing nitrogen levels in soils, natural waters, crop residues, li...To feed an increasing population, large amounts of chemical nitrogen fertilizer have been used to produce much of our food, feed and fiber thereby increasing nitrogen levels in soils, natural waters, crop residues, livestock wastes,and municipal and agricultural wastes, with national and international concern about its potential adverse effects on environmental quality and public health. To understand these phenomena and problems, first the nitrogen cycle and the environment are described. Then recent trends for nitrogen cycling through the food and feed system, N2O emissions from fertilized upland and paddy soils, and NO-3 pollution in ground water in Japan are reported. Finally, mitigation strategies in Japan for reducing N2O emission and NO-3 pollution are proposed, including nitrification inhibitors, controlled release fertilizers, utilization of plant species that could suppress nitrification, utilizing the toposequence, government policy, and appropriate agricultural practices. Of all the technologies presented, use of nitrification inhibitors and controlled release fertilizers are deemed the most important with further development of these aspects of technologies being expected. These practices, if employed worldwide, could help reduce the load, or environmental deterioration, on the Earth's biosphere.展开更多
To understand the water and energy exchange on the Qinghai-Tibetan Plateau, we explored the characteristics of evapotranspiration (ET) and energy fluxes from 2002 to 2005 over a Kobresia meadow ecosystem using the e...To understand the water and energy exchange on the Qinghai-Tibetan Plateau, we explored the characteristics of evapotranspiration (ET) and energy fluxes from 2002 to 2005 over a Kobresia meadow ecosystem using the eddy covariance method. The ratio of annual ET to precipitation (P) of meadow ecosystem was about 60%, but varied greatly with the change of season from summer to winter. The annual ET/P in meadow was lower than that in shrub, steppe and wetland ecosystems of this plateau. The incident solar radiation (Rs) received by the meadow was obviously higher than that of lowland in the same latitude; however the ratio of net radiation (Rn) to Rs with average annual value of 0.44 was significantly lower than that in the same latitude. The average annual ET was about 390 mm for 2002-2005, of which more than 80% occurred in growing season from May to September. The energy consumed on the ET was about 44% of net radiation in growing season, which was lower than that of shrub, steppe and wetland on this plateau. This study demonstrates that the Kobresia meadow may prevent the excessive water loss through evapotranspiration from the ecosystem into the atmosphere in comparison to the shrub, steppe and wetland ecosystems of the Qinghai-Tibetan Plateau.展开更多
The 137Cs vertical distributions in uncultivated and cultivated soils, developed from Quaternary red clay, granite, argillaceous shale, and red sandstone, were studied to develop reliable guidelines for selecting refe...The 137Cs vertical distributions in uncultivated and cultivated soils, developed from Quaternary red clay, granite, argillaceous shale, and red sandstone, were studied to develop reliable guidelines for selecting reference sites in southeastern China, which is dominated by strong acidic and/or clay-textured soils, and examine their reliability by comparing them to the reported 137Cs reference inventory data to see whether they agreed with the global distribution pattern. It was observed that a relatively high proportion of 137Cs was concentrated in the surface layers of soils with relatively high clay content. In the paddy soils developed from granite more 137Cs penetrated to depths below the plow layer (about 45.3%), when compared to those from the other three parent materials. The relatively low soil 137Cs inventories on crests excluded using the crest as the 137Cs reference site; instead the paddy field on the hillock plain was selected. Furthermore, within a specific county characterized by great systematic spatial variations of rainfall and topography across the landscape, a significant (P<0.01) and positive linear relationship (r2=0.81) between local 137Cs inventory and corresponding local annual rainfall was observed. Thus, for areas with large variations in rainfall, a single uniform value of local 137Cs reference inventory should be used with caution.展开更多
Ficus (Moraceae) is a well-known group with specific pollination mutualisms, and hybridization is considered to be rare. Here, we report the presence of interspecific hybrids between Ficus pumila L. and F. thunbergii ...Ficus (Moraceae) is a well-known group with specific pollination mutualisms, and hybridization is considered to be rare. Here, we report the presence of interspecific hybrids between Ficus pumila L. and F. thunbergii Maxim. on Okinoshima, a small island offshore of Shikoku, western Japan. AFLP (amplified fragment length polymorphism of genomic DNA) data suggested that more than one-fourth of individuals of morphological F. pumila were assigned as intermediate genotypes, suggesting hybrids. The hybridization between the two species was introgressive and unidirectional from F. thunbergii to F. pumila. The findings of this study, combined with other previous reports, suggest that the breakdown of mutualistic systems can occur in isolated populations such as those on islands.展开更多
Restoring natural forests after field abandon- ment is a land management objective that fosters the re- covery of forest biodiversity. We performed seeding and transplanting of native tree species 40 years after the a...Restoring natural forests after field abandon- ment is a land management objective that fosters the re- covery of forest biodiversity. We performed seeding and transplanting of native tree species 40 years after the abandonment of an arable field that became dominated by a dwarf bamboo (Pleioblastus chino (Franch. et Sav.) Makino) and by kudzu (Pueraria lobata (Willd.) Ohwi). By permutation tests, the removal of competing vegetation (gap creation) significantly increased the survival of three seeded species of Fagaceae and of eight transplanted spe- cies. In contrast, intact vegetation prevented most indi- viduals of all species from surviving for 1 year after planting. The lack of natural recruitment of Fagaceae in the nonseeded subplots indicated that seed limitation was a cause of the slow afforestation. Although litter accumula- tion in gaps at the time of seeding slightly increased sur- vival for late-germinating Quercus myrsinifolia Blume andCastanopsis sieboldii (Makino) Hatus. ex T. Yamaz. et Mashiba, the effect was not consistent among plots and was not statistically significant. Our results suggest that for successful afforestation using native trees in abandoned fields, it will be necessary to remove competitive native species to avoid severe limitations on microsite availability and that simultaneous tree establishment by seeding or transplanting should be implemented to accelerate the establishment of native tree species.展开更多
A greenhouse experiment was conducted to determine the influence of the environmental factors such as low-temperature, drought stress, salt-alkali and flooding on the survival rate, propagation rate, fresh biomass and...A greenhouse experiment was conducted to determine the influence of the environmental factors such as low-temperature, drought stress, salt-alkali and flooding on the survival rate, propagation rate, fresh biomass and viability of the Altemanthera philoxeroides and its competitive ability against rice by using bioassay method. A high viability of 84% was found when the stems were treated at 4℃ and then grew under normal conditions, while no viable plant was noted when the stems were treated at -20℃ and grew under normal conditions. Compared to the fresh stem with water content of 93.5%, the survival rate, number of propagated stems and fresh biomass of A. philoxeroides derived from the stems with water content of 30.2% were reduced by 45%, 33% and 74% respectively. The treatments of 0.1% salt-alkaline solution led to loss of viability of A, philoxeroides. The stems of A. philoxeroides could grow in wet soil with different depths of water-layer. The A. philoxeroides at density of 23-180 plants/m^2 reduced the rice grain yield by 43-50% at the rice plant density of 100 plants/m^2.展开更多
Natural forest recovery on abandoned farmland is hindered by a variety of factors and active restoration plays an important role when quick afforestation is desired. We investigated seedling survival of four transplan...Natural forest recovery on abandoned farmland is hindered by a variety of factors and active restoration plays an important role when quick afforestation is desired. We investigated seedling survival of four transplanted native tree species (Quercus myrsinifolia, Quercus serrata, Aphananthe aspera, and Rhus sylvestris) by experimentally manipulating the vegetation cover, which was mainly dominated by dwarf bamboo (Pleioblastus chino), and herbivore access to the planting sites on farmland that had been abandoned for 15 years at the start of the study. Few transplanted seedlings of any species survived under intact vegetation cover, irrespective of herbivore presence. In gaps in the vegetation cover, winter browsing by Japanese hare (Lepus brachyurus) damaged all species. However, lower browsing frequency and higher resprouting ability after grazing of the seedlings enabled both Quercus species to survive better than the other species. These results indicate that dwarf bamboo and the hare jointly limit the establishment of native trees in old fields. If active afforestation by transplanting seedlings at sites dominated by dwarf bamboo is planned, a combination of vegetation removal, selection of suitable species, and temporary seedling protection will be most effective.展开更多
The methanol extracts of 168 plant species from 68 families were evaluated for their inhibitory activity against lettuce seedling elongation. Among the plant species tested, 12 species had EC50 values for radicle grow...The methanol extracts of 168 plant species from 68 families were evaluated for their inhibitory activity against lettuce seedling elongation. Among the plant species tested, 12 species had EC50 values for radicle growth inhibition ranging from 0.01 to 5.00 mg fresh weight equivalent mL-1. Enterolobium contortisiliquum, a traditionally used herbal medicine, exhibited the strongest inhibitory activity (estimated EC50: 0.28 fresh weight equivalent mL-1). Among the 12 species, Pachysandra terminalis, Tamarindus indica, and Albizia guachapele required investigation, because only little has been reported about their chemical constituents to date. The data in the present study would be useful in finding new lead compounds for natural herbicides.展开更多
The objectives of this study were to demonstrate ethno-scientific elicitation techniques in retrieving indigenous knowledge at village-level, and to document the indigenous soil classification systems of different eth...The objectives of this study were to demonstrate ethno-scientific elicitation techniques in retrieving indigenous knowledge at village-level, and to document the indigenous soil classification systems of different ethnic groups in Luang Prabang province in the Lao PDR. The study area comprised three villages – Nambo, Huaymaha and Thapo, in the Phonxay district of Luang Prabang province. Three ethnic groups were covered by the study – Hmong, Khmu and Lao Loum. All three ethnic groups used soil color as main criteria for soil classification. However, even within the same ethnic group, sometimes different villages have differences in the way they classify soils; this was apparent for the Hmong ethnic group in the villages of Huaymaha and Nambo. A significant difference of the Lao Loum ethnic group from the other two, was the emphasis used in classifying soil types according to their water holding capabilities. In contrast, the Khmu and Hmong classified many soil types in relation to their rock content (‘with rock’ or ‘pure rock’ sometimesbeing used). The results of the study suggest that the ethnic groups classify the soils in relation to their potential for different types of agricultural production.展开更多
We studied human perceptions on the management of bamboo-tree gardens in two villages with contrasting agroecological conditions in the upper Citarum basin. We undertook interviews to reveal perceptions on the tenure,...We studied human perceptions on the management of bamboo-tree gardens in two villages with contrasting agroecological conditions in the upper Citarum basin. We undertook interviews to reveal perceptions on the tenure, function, and management strategies of multi-layered agroforest. Owners in a village located lower in the basin perceived the gardens more positively than those in an upland village, where market pressures were felt more keenly and for a longer period. There was not always a direct correlation between perceptions and behavior with respect to bamboo-tree garden management. However, we concluded that an understanding of human perceptions could provide valuable insight to the process of formulating strategies that might be effective in minimizing the conversion of bamboo-tree gardens to more intensive and less ecologically diverse agricultural systems. Specifically, since the villagers retained a strong cultural perception of the heritage value of the bamboo-tree gardens, they would likely be responsive to conservation efforts that increased the economic value of the gardens and reduced the opportunity cost of not converting them to production that is more intensive or other land uses.展开更多
Using the eddy covariance method,from 1 July2003 to 30 June 2004, we conducted the observation andanalysis of ecosystem CO2 flux in 3 types of alpine meadowvegetation (Kobresia humilis, Potentilla fruticosa shrub andK...Using the eddy covariance method,from 1 July2003 to 30 June 2004, we conducted the observation andanalysis of ecosystem CO2 flux in 3 types of alpine meadowvegetation (Kobresia humilis, Potentilla fruticosa shrub andKobresia tibetica swamp meadows) on the Qinghai-TibetanPlateau. The results show that the Kobresia humilis meadow,the shrub meadow and the swamp meadow’s highest CO2uptake rates are 16.78, 10.42 and 16.57 μmol·m?2·s?1respectively, while their highest CO2 release rates are 8.22,7.73 and 18.67 μmol·m?2·s?1 respectively. The Kobresiahumilis meadow and shrub meadow’s annual atmosphericuptakes are 282 g CO2/m2 and 53 g CO2/m2, respectively,while swamp meadow’s annual atmospheric release is 478 gCO2/m2. This proves that the Kobresia humilis meadow andthe shrub meadow on the Qinghai-Tibetan Plateau haverelatively low potential for CO2 uptake and release comparedto C4 grasslands, a number of lowland grasslands, andforests. Moreover, swamp meadow has relatively high releasepotential. This, in turn, reveals clear differences in carbonsource/sink between different types of vegetation in theQinghai-Tibetan Plateau alpine meadow ecosystem. Thesedifferences are mainly brought by differences in thevegetations’ photosynthetic capacity and soil respiration.展开更多
The effectiveness of polyolefin-coated urea (Meister-5 and Meister-10; CU) in a wheat (Triticum aestivum L.)-maize (Zea mays L.) rotation system was studied in lysimeter plots located in the North China Plain for thre...The effectiveness of polyolefin-coated urea (Meister-5 and Meister-10; CU) in a wheat (Triticum aestivum L.)-maize (Zea mays L.) rotation system was studied in lysimeter plots located in the North China Plain for three consecutive maize- wheat-maize cropping seasons. An isotopic method was used to compare the fate of CU to that of non-coated urea (NCU), and N application rates of 0, 100, 150 and 225 kg N ha-1 were evaluated. The results showed that the nitrogen use effciency (15NUE) of CU was 13.3%–21.4% greater than that of NCU for the first crop. Alternatively, when the difference method was applied (apparent NUE), no significant variations were observed among treatments in all three seasons. Although inorganic N leached from the 1.3 m layer was less than 1% of the total applied N, unidentified losses of 15N (losses of 15N = 15N applied as fertilizer – 15N absorbed by crops – 15N remaining in the 0–0.2 m layer – 15N leached from the 1.3 m layer) in CU-treated plots were 24.2%–26.5% lower than those of NCU-treated plots. The nitrate concentration in the 0–1.3 m layer of CU plots at the end of the experiment was 53% lower than that of NCU-treated plots. Thus, CU increased crop N uptake from fertilizer and reduced unidentified losses of applied N, which can reduce the risk of groundwater pollution.展开更多
Studies showed that elevated [CO2] would improve photosynthetic rates and enhance yields of rice;however,few studies have focused on the response of rice lodging,which is a major cause of cereal yield loss and quality...Studies showed that elevated [CO2] would improve photosynthetic rates and enhance yields of rice;however,few studies have focused on the response of rice lodging,which is a major cause of cereal yield loss and quality reduction,under elevated [CO2].In this study,we examined the effects of elevated [CO2] on stem and root lodging using 4 rice cultivars(86Y8,japonica hybrid;LYP9,2-line indica hybrid;variety 9311,type of indica inbred rice,and SY63,3-line indica hybrid) grown under two [CO2] levels:400 and 680 μmol mol-1.Our results indicated that under elevated [CO2],the stem-lodging risk(SLR) of 9311 decreased,while in SY63 the SLR increased,86Y8 and LYP9 were not significantly affected;the risk of root lodging was reduced for all cultivars,because root biomass(instead of root number) and bending strength were increased significantly,and then the increase of anti-lodging ability is far higher than that of self-weight mass moment for all cultivars.These findings suggested that higher [CO2] can enhance the risk of stem-lodging for cultivars with strong-[CO2]-responses,but may not aggravate the root lodging for all rice cultivars.展开更多
To analyze the effect of agricultural activity on nitrogen(N) budget at the watershed scale,a comparative study was conducted at two Japanese watersheds,the Shibetsu River watershed(SRW) and Upper-Naka River watershed...To analyze the effect of agricultural activity on nitrogen(N) budget at the watershed scale,a comparative study was conducted at two Japanese watersheds,the Shibetsu River watershed(SRW) and Upper-Naka River watershed(UNRW),and one Chinese watershed,the Jurong Reservoir watershed(JRW).The total area and the proportion of agricultural area(in parentheses) of the watersheds were 685(51%),1 299(21%),and 46 km 2(55%) for SRW,UNRW,and JRW,respectively.The main agricultural land use in SRW was forage grassland,while paddy fields occupied the highest proportion of cropland in UNRW(11% of total area) and JRW(31% of total area).The farmland surplus N was 61,48,and 205 kg N ha 1 year 1 for SRW,UNRW,and JRW,respectively.The total input and output for the whole watershed were 89 and 76,83 and 61,and 353 and 176 kg N ha 1 year 1 for SRW,UNRW,and JRW,respectively.The proportion of discharged N to net anthropogenic N input was 31%,37%,and 1.7% for SRW,UNRW,and JRW,respectively.The two watersheds in Japan showed similar proportions of discharged N to those of previous reports,while the watershed in China(JRW) showed a totally different characteristic compared to previous studies.The high N input in JRW did not increase the amount of discharged N at the outlet of the watershed due to high proportions of paddy fields and water bodies,which was an underestimated N sink at the landscape scale.展开更多
1 Introduction In 2013,Chagusaba,which is traditional tea-grass integrated system in Shizuoka,were accepted as new world heritage site of agriculture.Shizuoka prefecture occupies a variety of elevations,from 0 to 3000...1 Introduction In 2013,Chagusaba,which is traditional tea-grass integrated system in Shizuoka,were accepted as new world heritage site of agriculture.Shizuoka prefecture occupies a variety of elevations,from 0 to 3000m or more above sea level.Because of the diversity of land features and climates,this area produces 167 agricultural commodities.In addition,a lot of traditional agriculture and over200 local native varieties of crops have been conserved in展开更多
文摘人类活动导致的大气和气候变化将极大地改变作物的生长环境,其中最大的一个变化就是大气二氧化碳(CO2)浓度的迅速上升:从工业革命前的平均270μmol/mol上升到目前的381μmol/mol,到2050年至少超过550μmol/mol。FACE(Free-air CO2 enrichment,开放式空气中CO2浓度增高)试验是目前评估未来高浓度CO2对作物生长和产量实际影响的最佳方法。水稻无疑是人类最重要的食物来源,迄今为止人类利用FACE技术开展水稻响应和适应的研究已有10a(19982008年)的历史。以生长发育为主线,首次系统综述了10a水稻FACE试验在该领域的研究成果,总结了FACE情形下高浓度CO2(模拟本世纪中叶大气CO2浓度)对主要供试水稻品种(小区面积大于4m2)光合作用、生育进程、地上部生长、地下部生长、物质分配、籽粒灌浆、产量构成以及倒伏性状等影响的研究进展,比较了FACE与非FACE研究之间以及中国和日本FACE研究(世界上唯一的两个大型水稻FACE研究)之间的异同点。根据研究进展以及当前的技术水平,文章最后提出了该领域的3个优先课题:(1)FACE情形下杂交稻生产力响应高于预期的生物学机制;(2)FACE情形下CO2与主要栽培措施的互作效应;(3)FACE情形下CO2与主要空气污染物臭氧的互作效应。这些响应的机理性解析将有助于从根本上减少人类预测未来粮食安全的不确定性,进而更加有效地制订出应对全球变化的适应策略。
基金Project supported by the Canadian International Development Agency, Canada and the Chinese Academy of Scicences, China (No. KZCX2-413)
文摘To feed an increasing population, large amounts of chemical nitrogen fertilizer have been used to produce much of our food, feed and fiber thereby increasing nitrogen levels in soils, natural waters, crop residues, livestock wastes,and municipal and agricultural wastes, with national and international concern about its potential adverse effects on environmental quality and public health. To understand these phenomena and problems, first the nitrogen cycle and the environment are described. Then recent trends for nitrogen cycling through the food and feed system, N2O emissions from fertilized upland and paddy soils, and NO-3 pollution in ground water in Japan are reported. Finally, mitigation strategies in Japan for reducing N2O emission and NO-3 pollution are proposed, including nitrification inhibitors, controlled release fertilizers, utilization of plant species that could suppress nitrification, utilizing the toposequence, government policy, and appropriate agricultural practices. Of all the technologies presented, use of nitrification inhibitors and controlled release fertilizers are deemed the most important with further development of these aspects of technologies being expected. These practices, if employed worldwide, could help reduce the load, or environmental deterioration, on the Earth's biosphere.
基金supported by the National Natural Science Foundation of China(31070433)Japan-China Research Cooperative Program(2010DFA31290)supported by the project of Early Detection and Prediction of Climate Warming Based on the Long-Term Monitoring of Alpine Ecosystems on the Tibetan Plateau funded by the Ministry of Environment,Japan
文摘To understand the water and energy exchange on the Qinghai-Tibetan Plateau, we explored the characteristics of evapotranspiration (ET) and energy fluxes from 2002 to 2005 over a Kobresia meadow ecosystem using the eddy covariance method. The ratio of annual ET to precipitation (P) of meadow ecosystem was about 60%, but varied greatly with the change of season from summer to winter. The annual ET/P in meadow was lower than that in shrub, steppe and wetland ecosystems of this plateau. The incident solar radiation (Rs) received by the meadow was obviously higher than that of lowland in the same latitude; however the ratio of net radiation (Rn) to Rs with average annual value of 0.44 was significantly lower than that in the same latitude. The average annual ET was about 390 mm for 2002-2005, of which more than 80% occurred in growing season from May to September. The energy consumed on the ET was about 44% of net radiation in growing season, which was lower than that of shrub, steppe and wetland on this plateau. This study demonstrates that the Kobresia meadow may prevent the excessive water loss through evapotranspiration from the ecosystem into the atmosphere in comparison to the shrub, steppe and wetland ecosystems of the Qinghai-Tibetan Plateau.
基金Project supported by the National Key Basic Research Support Foundation of China (No. G1999011801) the National Natural Science Foundation of China (No. 49973027)and Japan Society for the Promotion of Science (No. P04575).
文摘The 137Cs vertical distributions in uncultivated and cultivated soils, developed from Quaternary red clay, granite, argillaceous shale, and red sandstone, were studied to develop reliable guidelines for selecting reference sites in southeastern China, which is dominated by strong acidic and/or clay-textured soils, and examine their reliability by comparing them to the reported 137Cs reference inventory data to see whether they agreed with the global distribution pattern. It was observed that a relatively high proportion of 137Cs was concentrated in the surface layers of soils with relatively high clay content. In the paddy soils developed from granite more 137Cs penetrated to depths below the plow layer (about 45.3%), when compared to those from the other three parent materials. The relatively low soil 137Cs inventories on crests excluded using the crest as the 137Cs reference site; instead the paddy field on the hillock plain was selected. Furthermore, within a specific county characterized by great systematic spatial variations of rainfall and topography across the landscape, a significant (P<0.01) and positive linear relationship (r2=0.81) between local 137Cs inventory and corresponding local annual rainfall was observed. Thus, for areas with large variations in rainfall, a single uniform value of local 137Cs reference inventory should be used with caution.
文摘Ficus (Moraceae) is a well-known group with specific pollination mutualisms, and hybridization is considered to be rare. Here, we report the presence of interspecific hybrids between Ficus pumila L. and F. thunbergii Maxim. on Okinoshima, a small island offshore of Shikoku, western Japan. AFLP (amplified fragment length polymorphism of genomic DNA) data suggested that more than one-fourth of individuals of morphological F. pumila were assigned as intermediate genotypes, suggesting hybrids. The hybridization between the two species was introgressive and unidirectional from F. thunbergii to F. pumila. The findings of this study, combined with other previous reports, suggest that the breakdown of mutualistic systems can occur in isolated populations such as those on islands.
文摘Restoring natural forests after field abandon- ment is a land management objective that fosters the re- covery of forest biodiversity. We performed seeding and transplanting of native tree species 40 years after the abandonment of an arable field that became dominated by a dwarf bamboo (Pleioblastus chino (Franch. et Sav.) Makino) and by kudzu (Pueraria lobata (Willd.) Ohwi). By permutation tests, the removal of competing vegetation (gap creation) significantly increased the survival of three seeded species of Fagaceae and of eight transplanted spe- cies. In contrast, intact vegetation prevented most indi- viduals of all species from surviving for 1 year after planting. The lack of natural recruitment of Fagaceae in the nonseeded subplots indicated that seed limitation was a cause of the slow afforestation. Although litter accumula- tion in gaps at the time of seeding slightly increased sur- vival for late-germinating Quercus myrsinifolia Blume andCastanopsis sieboldii (Makino) Hatus. ex T. Yamaz. et Mashiba, the effect was not consistent among plots and was not statistically significant. Our results suggest that for successful afforestation using native trees in abandoned fields, it will be necessary to remove competitive native species to avoid severe limitations on microsite availability and that simultaneous tree establishment by seeding or transplanting should be implemented to accelerate the establishment of native tree species.
基金This paper was translated from its Chinese version in Chinese Journal of Rice Science.
文摘A greenhouse experiment was conducted to determine the influence of the environmental factors such as low-temperature, drought stress, salt-alkali and flooding on the survival rate, propagation rate, fresh biomass and viability of the Altemanthera philoxeroides and its competitive ability against rice by using bioassay method. A high viability of 84% was found when the stems were treated at 4℃ and then grew under normal conditions, while no viable plant was noted when the stems were treated at -20℃ and grew under normal conditions. Compared to the fresh stem with water content of 93.5%, the survival rate, number of propagated stems and fresh biomass of A. philoxeroides derived from the stems with water content of 30.2% were reduced by 45%, 33% and 74% respectively. The treatments of 0.1% salt-alkaline solution led to loss of viability of A, philoxeroides. The stems of A. philoxeroides could grow in wet soil with different depths of water-layer. The A. philoxeroides at density of 23-180 plants/m^2 reduced the rice grain yield by 43-50% at the rice plant density of 100 plants/m^2.
文摘Natural forest recovery on abandoned farmland is hindered by a variety of factors and active restoration plays an important role when quick afforestation is desired. We investigated seedling survival of four transplanted native tree species (Quercus myrsinifolia, Quercus serrata, Aphananthe aspera, and Rhus sylvestris) by experimentally manipulating the vegetation cover, which was mainly dominated by dwarf bamboo (Pleioblastus chino), and herbivore access to the planting sites on farmland that had been abandoned for 15 years at the start of the study. Few transplanted seedlings of any species survived under intact vegetation cover, irrespective of herbivore presence. In gaps in the vegetation cover, winter browsing by Japanese hare (Lepus brachyurus) damaged all species. However, lower browsing frequency and higher resprouting ability after grazing of the seedlings enabled both Quercus species to survive better than the other species. These results indicate that dwarf bamboo and the hare jointly limit the establishment of native trees in old fields. If active afforestation by transplanting seedlings at sites dominated by dwarf bamboo is planned, a combination of vegetation removal, selection of suitable species, and temporary seedling protection will be most effective.
文摘The methanol extracts of 168 plant species from 68 families were evaluated for their inhibitory activity against lettuce seedling elongation. Among the plant species tested, 12 species had EC50 values for radicle growth inhibition ranging from 0.01 to 5.00 mg fresh weight equivalent mL-1. Enterolobium contortisiliquum, a traditionally used herbal medicine, exhibited the strongest inhibitory activity (estimated EC50: 0.28 fresh weight equivalent mL-1). Among the 12 species, Pachysandra terminalis, Tamarindus indica, and Albizia guachapele required investigation, because only little has been reported about their chemical constituents to date. The data in the present study would be useful in finding new lead compounds for natural herbicides.
文摘The objectives of this study were to demonstrate ethno-scientific elicitation techniques in retrieving indigenous knowledge at village-level, and to document the indigenous soil classification systems of different ethnic groups in Luang Prabang province in the Lao PDR. The study area comprised three villages – Nambo, Huaymaha and Thapo, in the Phonxay district of Luang Prabang province. Three ethnic groups were covered by the study – Hmong, Khmu and Lao Loum. All three ethnic groups used soil color as main criteria for soil classification. However, even within the same ethnic group, sometimes different villages have differences in the way they classify soils; this was apparent for the Hmong ethnic group in the villages of Huaymaha and Nambo. A significant difference of the Lao Loum ethnic group from the other two, was the emphasis used in classifying soil types according to their water holding capabilities. In contrast, the Khmu and Hmong classified many soil types in relation to their rock content (‘with rock’ or ‘pure rock’ sometimesbeing used). The results of the study suggest that the ethnic groups classify the soils in relation to their potential for different types of agricultural production.
文摘We studied human perceptions on the management of bamboo-tree gardens in two villages with contrasting agroecological conditions in the upper Citarum basin. We undertook interviews to reveal perceptions on the tenure, function, and management strategies of multi-layered agroforest. Owners in a village located lower in the basin perceived the gardens more positively than those in an upland village, where market pressures were felt more keenly and for a longer period. There was not always a direct correlation between perceptions and behavior with respect to bamboo-tree garden management. However, we concluded that an understanding of human perceptions could provide valuable insight to the process of formulating strategies that might be effective in minimizing the conversion of bamboo-tree gardens to more intensive and less ecologically diverse agricultural systems. Specifically, since the villagers retained a strong cultural perception of the heritage value of the bamboo-tree gardens, they would likely be responsive to conservation efforts that increased the economic value of the gardens and reduced the opportunity cost of not converting them to production that is more intensive or other land uses.
基金This work was supported by the Chinese Acad-emy of Science's Innovation Program(Grant No.KZCX1-SW-01-01A5)the 973.Program(Grant No.2002cb4 125ol)+1 种基金two joint Sino-Japanese projects:“Asia-Pacific Environmental Innovation Strategy Project(APEIS)""Research on the Effects of Carbon Dynamics and Global warming on Temperate Highland Grasslands”
文摘Using the eddy covariance method,from 1 July2003 to 30 June 2004, we conducted the observation andanalysis of ecosystem CO2 flux in 3 types of alpine meadowvegetation (Kobresia humilis, Potentilla fruticosa shrub andKobresia tibetica swamp meadows) on the Qinghai-TibetanPlateau. The results show that the Kobresia humilis meadow,the shrub meadow and the swamp meadow’s highest CO2uptake rates are 16.78, 10.42 and 16.57 μmol·m?2·s?1respectively, while their highest CO2 release rates are 8.22,7.73 and 18.67 μmol·m?2·s?1 respectively. The Kobresiahumilis meadow and shrub meadow’s annual atmosphericuptakes are 282 g CO2/m2 and 53 g CO2/m2, respectively,while swamp meadow’s annual atmospheric release is 478 gCO2/m2. This proves that the Kobresia humilis meadow andthe shrub meadow on the Qinghai-Tibetan Plateau haverelatively low potential for CO2 uptake and release comparedto C4 grasslands, a number of lowland grasslands, andforests. Moreover, swamp meadow has relatively high releasepotential. This, in turn, reveals clear differences in carbonsource/sink between different types of vegetation in theQinghai-Tibetan Plateau alpine meadow ecosystem. Thesedifferences are mainly brought by differences in thevegetations’ photosynthetic capacity and soil respiration.
基金Supported by the National Basic Research Program (973 Program) of China (No. 2007CB109302)the Special Fund for Agro-Scientific Research in the Public Interest, China (No. 201103007)the Japan-China Co-operation Project
文摘The effectiveness of polyolefin-coated urea (Meister-5 and Meister-10; CU) in a wheat (Triticum aestivum L.)-maize (Zea mays L.) rotation system was studied in lysimeter plots located in the North China Plain for three consecutive maize- wheat-maize cropping seasons. An isotopic method was used to compare the fate of CU to that of non-coated urea (NCU), and N application rates of 0, 100, 150 and 225 kg N ha-1 were evaluated. The results showed that the nitrogen use effciency (15NUE) of CU was 13.3%–21.4% greater than that of NCU for the first crop. Alternatively, when the difference method was applied (apparent NUE), no significant variations were observed among treatments in all three seasons. Although inorganic N leached from the 1.3 m layer was less than 1% of the total applied N, unidentified losses of 15N (losses of 15N = 15N applied as fertilizer – 15N absorbed by crops – 15N remaining in the 0–0.2 m layer – 15N leached from the 1.3 m layer) in CU-treated plots were 24.2%–26.5% lower than those of NCU-treated plots. The nitrate concentration in the 0–1.3 m layer of CU plots at the end of the experiment was 53% lower than that of NCU-treated plots. Thus, CU increased crop N uptake from fertilizer and reduced unidentified losses of applied N, which can reduce the risk of groundwater pollution.
基金supported by the Ministry of Agriculture,Forestry and Fisheries of Japan project,"Development of technology for mitigation and adaptation to climate change in Agriculture,Forestry and Fisheries"a Grant-in-Aid for Scientific Research (P09515) from the Japan Society forthe Promotion of Science
文摘Studies showed that elevated [CO2] would improve photosynthetic rates and enhance yields of rice;however,few studies have focused on the response of rice lodging,which is a major cause of cereal yield loss and quality reduction,under elevated [CO2].In this study,we examined the effects of elevated [CO2] on stem and root lodging using 4 rice cultivars(86Y8,japonica hybrid;LYP9,2-line indica hybrid;variety 9311,type of indica inbred rice,and SY63,3-line indica hybrid) grown under two [CO2] levels:400 and 680 μmol mol-1.Our results indicated that under elevated [CO2],the stem-lodging risk(SLR) of 9311 decreased,while in SY63 the SLR increased,86Y8 and LYP9 were not significantly affected;the risk of root lodging was reduced for all cultivars,because root biomass(instead of root number) and bending strength were increased significantly,and then the increase of anti-lodging ability is far higher than that of self-weight mass moment for all cultivars.These findings suggested that higher [CO2] can enhance the risk of stem-lodging for cultivars with strong-[CO2]-responses,but may not aggravate the root lodging for all rice cultivars.
基金Supported by the Strategic International Cooperative Program "Comparative Study of Nitrogen Cycling and Its Impact on Water Quality in Agricultural Watersheds in Japan and China" by the Japan Science and Technology Agency and the National Natural Science Foundation of China(No.41071196)
文摘To analyze the effect of agricultural activity on nitrogen(N) budget at the watershed scale,a comparative study was conducted at two Japanese watersheds,the Shibetsu River watershed(SRW) and Upper-Naka River watershed(UNRW),and one Chinese watershed,the Jurong Reservoir watershed(JRW).The total area and the proportion of agricultural area(in parentheses) of the watersheds were 685(51%),1 299(21%),and 46 km 2(55%) for SRW,UNRW,and JRW,respectively.The main agricultural land use in SRW was forage grassland,while paddy fields occupied the highest proportion of cropland in UNRW(11% of total area) and JRW(31% of total area).The farmland surplus N was 61,48,and 205 kg N ha 1 year 1 for SRW,UNRW,and JRW,respectively.The total input and output for the whole watershed were 89 and 76,83 and 61,and 353 and 176 kg N ha 1 year 1 for SRW,UNRW,and JRW,respectively.The proportion of discharged N to net anthropogenic N input was 31%,37%,and 1.7% for SRW,UNRW,and JRW,respectively.The two watersheds in Japan showed similar proportions of discharged N to those of previous reports,while the watershed in China(JRW) showed a totally different characteristic compared to previous studies.The high N input in JRW did not increase the amount of discharged N at the outlet of the watershed due to high proportions of paddy fields and water bodies,which was an underestimated N sink at the landscape scale.
文摘1 Introduction In 2013,Chagusaba,which is traditional tea-grass integrated system in Shizuoka,were accepted as new world heritage site of agriculture.Shizuoka prefecture occupies a variety of elevations,from 0 to 3000m or more above sea level.Because of the diversity of land features and climates,this area produces 167 agricultural commodities.In addition,a lot of traditional agriculture and over200 local native varieties of crops have been conserved in