China is a disaster prone country, and a comprehensive understanding of change of disasters is very important for China＇s agricultural development. In this study, statistical tech niques and geographic information sy...China is a disaster prone country, and a comprehensive understanding of change of disasters is very important for China＇s agricultural development. In this study, statistical tech niques and geographic information system tools are employed to quantify the main agricul ture disasters changes and effects on grain production in China during the period of 1990-2011. The results show that China＇s grain production was severely affected by disas ters including drought, flood, hail, frost and typhoon. The annual area covered by these dis asters reached up to 48.7x106 ha during the study period, which accounted for 44.8% of the total sown area, and about 55.1% of the per unit area grain yield change was caused by disasters. In addition, all of the disasters showed high variability, different changing trends, and spatial distribution. Drought, flood, and hail showed significantly decreasing trends, while frost and typhoon showed increasing trends. Drought and flood showed gradual changes and were distributed across the country, and disasters became more diversified from north to south. Drought was the dominated disaster type in northern China, while flood was the most important disaster type in the southern part. Hail was mainly observed in central and northern China, and frost was mainly distributed in southern China. Typhoon was greatly limited to the southeast coast. Furthermore, the resilience of grain production of each province was quite different, especially in several major grain producing areas, such as Shandong, Liaoning, Jilin and Jiangsu, where grain production was seriously affected by disasters. One reason for the difference of resilience of grain production was that grain production was marginalized in developed provinces when the economy underwent rapid development. For China＇s agricul tural development and grain security, we suggest that governments should place more em phasis on grain production, and invest more money in disaster prevention and mitigation, especially in the major grain producing provinces.展开更多
As the world’s largest developing country,the ability of China’s agricultural resource utilization to effectively support the current and future food security goals has been affected by a variety of factors(e.g.,tra...As the world’s largest developing country,the ability of China’s agricultural resource utilization to effectively support the current and future food security goals has been affected by a variety of factors(e.g.,transformed supply channels,tightening international situation and frequent emergencies)in recent years and has attracted extensive attention from the academic community subject to multiple factors.This study uses literature review,statistical analysis,and spatial analysis methods to systematically explore China’s food security situation in the context of farmland resource constraints.It is found that the demand-side pressures such as demographic changes,social class differentiation,and dietary structure adjustments derived from economic growth and rapid urbanization have placed extremely high expectations on food supply.However,the quantitative restrictions,utilization ways,and health risks of farmland resources on the supply side constitute a huge hidden concern that affects the stability of food production.Although China’s farmland protection system is undergoing a transition from focusing on quantity management to sustainable use,the matching and coordinating demand pressure and supply capacity for food security is unbalanced.Therefore,facing uncertain future development scenarios,policymakers should focus on building a resilient space for China’s farmland protection to withstand the interference of major emergencies.The existing farmland protection space policy can be integrated by establishing a national farmland strategic reserve system(based on resilient space),and further development of targeted use control measures for zoning,grading,and classification will help realize sustainable China’s farmland resources use.展开更多
This research reconstructs China＇s provincial farmland dataset in the last 300 years （1661-1985） by applying factor correction, citing replacement, linear interpolation, cohesion and contrast, man-land relationship...This research reconstructs China＇s provincial farmland dataset in the last 300 years （1661-1985） by applying factor correction, citing replacement, linear interpolation, cohesion and contrast, man-land relationship test, farming trend test, provincial administrative area adjustment, etc. on available farmland data based on China＇s current provincial administrative boundary. Based on this dataset, a quantitative analysis has been applied to study the farm- land amount and its change Characteristics at both national and provincial level. Three con- clusions are derived： （1） Along with the rapid population growth, national farmland amount has increased by about 320% in the last 300 years from 424,480 km2 in the early Qing Dy- nasty to 1,368,600 km2 in 1985. Comparing with global and national farmland datasets, in terms of the overall trend of national farmland growth, very low deviation exists but significant variances do appear for some provinces. （2） At the beginning of the Qing Dynasty, China＇s farming activities mainly existed in the Yangtze River Plain, the North China Plain, the Guanzhong Basin and the Yinchuan Plain. Thereafter, reclamation activities expanded to outer agricultural areas. Regarding of the growth rate, national farmland increase can be divided into five phases. National policy, disasters, wars, and economic development, are the main factors affecting farmland changes. （3） Significant regional variances exist in farmland changes. In the space shaped by the average farmland amount and the average annual change rate of farmland, the nation can be divided into six areas.展开更多
Systematically revealing the impact of cultivated land fragmentation(CLF)on the geographical agglomeration pattern of agricultural specialization(AS)has positive significance for national agricultural production manag...Systematically revealing the impact of cultivated land fragmentation(CLF)on the geographical agglomeration pattern of agricultural specialization(AS)has positive significance for national agricultural production management.Based on the data of the second national land survey and agricultural production,this study has explored the impact of CLF on spatial heterogeneity of agricultural agglomeration in China by comprehensively using the Theil index,ordinary least square model and geographically weighted regression.Results showed that:(1)the regional differentiation of the CLF in China is obvious,and the cultivated land fragmentation index is generally characterized by increasing pattern from northwest to southeast.(2)Spatially,the development level of AS in China has formed three high-value clusters in the Northeast China Plain,the Qinghai-Tibet Plateau,and the middle of the Middle-lower Yangtze Plain;and the low-value contiguous areas centered on the Yunnan-Guizhou Plateau and the Sichuan Basin and surrounding regions,with significant spatial differences.The contribution of grain crops,economic crops,and vegetables and melon to the level of AS was 74.63%,9.09%,and 16.28%,respectively,and the pattern of agricultural geographical aggregation dominated by grain crops has primarily taken in shape.(3)CLF is significantly negatively correlated with AS,and every 1%increase in the degree of CLF will result in a decrease of about 0.2%in AS.However,the impact of CLF on the geographic agglomeration of different crop categories or groups varies significantly.Among them,CLF has a prominent impact on the specialization level of grain crops and vegetables and melon.Each 1%increase in the CLF will reduce the specialization level of grain crops by 0.38%,and increase the level of vegetables and melon by about 0.22%.(4)According to the landscape characteristics of cultivated land,the degree of spatial division and agglomeration of cultivated land patches have a significant impact on the formation of geographical agglomerationpattern of AS,and the intensity and direction of influence show significant regional differentiation,while the patch size has no significant impact.展开更多
Detailed soil surveys involve costly and time-consuming work and require expert knowledge. Since soil surveys provide information to meet a wide range of needs, new methods are necessary to map soils quickly and accur...Detailed soil surveys involve costly and time-consuming work and require expert knowledge. Since soil surveys provide information to meet a wide range of needs, new methods are necessary to map soils quickly and accurately. In this study, multilayer perceptron artificial neural networks(ANNs) were developed to map soil units using digital elevation model(DEM) attributes. Several optimal ANNs were produced based on a number of input data and hidden units. The approach used test and validation areas to calculate the accuracy of interpolated and extrapolated data. The results showed that the system and level of soil classification employed had a direct effect on the accuracy of the results. At the lowest level, smaller errors were observed with the World Reference Base(WRB)classification criteria than the Soil Taxonomy(ST) system, but more soil classes could be predicted when using ST(7 soils in the case of ST vs. 5 with WRB). Training errors were below 11% for all the ANN models applied, while the test error(interpolation error) and validation error(extrapolation error) were as high as 50% and 70%, respectively. As expected, soil prediction using a higher level of classification presented a better overall level of accuracy. To obtain better predictions, in addition to DEM attributes, data related to landforms and/or lithology as soil-forming factors, should be used as ANN input data.展开更多
This study is proposed to reconstruct a high-resolution spatial distribution of historical land use pattern with all land use types to overcome low-accuracy and/or the monotonic land use type in current historical lan...This study is proposed to reconstruct a high-resolution spatial distribution of historical land use pattern with all land use types to overcome low-accuracy and/or the monotonic land use type in current historical land use reconstruction studies. The year of 1820 is set as the temporal section and the administrative area of Jiangsu Province is the study area. Land use types being reconstructed include farmland, residential land （including both urban land and rural residential land）, water body, and other land （including forest land, grassland, and unused land）. Data sources mainly refer to historical documents, historical geographic research outcomes, contemporary statistics, and natural environmental data. With great considerations over regional natural resources and social and economic conditions, a few theoretical assumptions have been proposed to facilitate the adjustment on prefecture farmland, urban land, and rural residential land. Upholding the idea that the contemporary land use pattern has been inherently in sequence with the historical land use pattern as well as the land use pattern shall be consistent to its accessibility, this study reconstructs the land use pattern in Jiangsu Province in 1820 with 100 m＊100 m grids based on accessibility analysis and comprehensive evaluation. The outcome has been tested as valid by regionalization and correlation analysis. The resulted spatial distribution shows that back in 1820 in Jiangsu Province： （1） farmland, urban land, rural residential land, water body, and other land take about 48.49%, 4.46%, 0.16%, 15.03%, and 31.86% of the total land area respectively; （2） the land use pattern features high proportion of land in farming while low-proportion land in non-farming uses while population, topography, and the density of water body lead to great spatial variations; and （3） the reconstruction methodology has been tested as reasonable based on significant positive correlations between 1820 data and 1985 for both farmland and rural residential land at the prefecture level.展开更多
Land cover is the most evident landscape signal to characterize the influence of human activities on terrestrial ecosystems. Since the industrial revolution, the expansion of construction land has profoundly changed t...Land cover is the most evident landscape signal to characterize the influence of human activities on terrestrial ecosystems. Since the industrial revolution, the expansion of construction land has profoundly changed the status of land use coverage and changes. This study is proposed to reconstruct the spatial pattern of construction land （urban construction land and rural settlement land） for five historical periods over the past 200 years in Jiangsu Province with 200 m × 200 m grids on the basis of quantitative estimation. Urban construction land is estimated based on data about city walls, four gates along walls, and other socio-economic factors. Rural settlement land is calculated based on the rural population and per capita housing allowance. The spatial pattern of historical construction land is simulated based on the distribution of modern construction land in 1985 with a quantitative-boundary- suitability control method and thorough consideration over connectivity of different land use types. The study concludes that： （1） the amount of construction land in Jiangsu Province is estimated at 963.46 km^2 in 1820, 1043.46 km^2 in 1911, 1672.40 km^2 in 1936, 1980.34 km^2 in 1952 and 10,687.20 km^2 in 1985; and （2） the spatial distribution of construction land features the great proclivity to water bodies and main roads and the strong polarization of existent residence. The results are verified directly and indirectly by applying the trend verification of construction land changes and patterns, the correlation analysis between rural settlement land and local arable land, and quantitative accuracy test of the reconstructed construction land to actual historical survey maps covering four sample regions in 1936.展开更多
Changes in groundwater level in Homand-Absard plain, located in north-west of Kavir-e-Markazi watershed and east of Tehran province, were studied. The used research method was descriptive approach, and the research st...Changes in groundwater level in Homand-Absard plain, located in north-west of Kavir-e-Markazi watershed and east of Tehran province, were studied. The used research method was descriptive approach, and the research study was conducted based on field and desk surveys. The data needed was provided from field surveys, contours maps, and data of observation wells. There were 17 observation wells in the study area where the changes in groundwater levels were measured during 1996-2013, and an index hydrograph was prepared for the aquifer of plain. The sharpest decline in the groundwater level was in the central of Homan-Absard plain. There was 1.43 m decline in the groundwater level of aquifer annually, compared with similar studies in other parts of Iran, it has a high rate, and to the average, the groundwater level of plain has dropped equal to 25.76 m, 1996-2013. According to the study findings, the groundwater level changes with those in rainfall weren't match and the drop in groundwater level during wet years and then has continued which represents the high water extraction factor on the groundwater level drop.展开更多
In this study, data of body weight at slaughter （SW; n = 465）, hot carcass weight （HCW; n = 465）, cold carcass weight （CCW; n = 401）, carcass lean weight （CLW; n = 314）, carcass bone weight （CBW; n = 401）, c...In this study, data of body weight at slaughter （SW; n = 465）, hot carcass weight （HCW; n = 465）, cold carcass weight （CCW; n = 401）, carcass lean weight （CLW; n = 314）, carcass bone weight （CBW; n = 401）, carcass total fat weight （CTFW; n = 314） and fat-tail weight （FTW; n = 401） in Lori-Bakhtiari sheep were measured to determine their possible use in breeding programmers aimed at improving ability to carcass quality in this breed. Lambs were slaughtered at 195 ＋ 27 days of age. The method of slaughtering and cultting was Iranian cutting approach. SAS procedures were used for the statistical analysis. Means and their respective standard deviations for SW, HCW, CCW, CLW, CBW, CTFW and FTW were 45.41 ± 6.86, 22.81 ± 4.32, 22.53 ± 4.18, 11.14 ± 1.71, 3.47 ± 0.43, 7.19 ± 2.42 and 3.65 ± 1.37 kg, respectively. The coefficients of variation for CTFW and FTW were 33.62 percent and 38.01 percent, respectively. Environmental effects of kind of rearing after weaning and type of birth on HCW, CCW, CLW, CTFW and FTW traits were significant. Consequently, considerable variation exists for carcass composition traits, especially for carcass fat and fat-tail.展开更多
This study was carried out during 2007-2009 in the vineyards of Ardebil province of lran to study the biology and the epidemiology of Uncinula necator--the causal agent of grape powdery mildew disease. The study conce...This study was carried out during 2007-2009 in the vineyards of Ardebil province of lran to study the biology and the epidemiology of Uncinula necator--the causal agent of grape powdery mildew disease. The study concentrated on the survival and the initiation of primary inoculum of the fungal causal agent. Results of histopathological experiments indicated that U. necator survived as mycelium in the dormant buds of the grapes during winter season. Results of study on the effect of environmental factors on fungus biology showed that the pathogenic activity of the fungus began when the temperature was between 16-19 ℃ with a relative humidity more than 50%. It was also found that optimum temperature and relative humidity for the sporulation of U.necator was 20-25 ~C and 50%-100% respectively. According to the results, fungal conidia were trapped during formation of 5-6 true leaves and first disease symptoms were observed on the clusters on late June after fruit formation. Fungal cleistothecia were observed abundantly at the end of season on the leaves, petioles and twigs but they were not able to survive during winter. Formation of ascospores on young leaves was proved but their role as the primary inoculum was not supported by the results of this study. Results of this study and the new findings on the biology and epidemiology of U.necator may be of national and international interests for the management of powdery mildew disease which is one of the most destructive diseases around the world including Iran.展开更多
The germination of freshly collected Juniperus polycarpos（K. Koch） seeds is very low and attributed to the large proportion of nonviable seeds in the seed lots.Thus, the aim of this study was to improve seed lot qua...The germination of freshly collected Juniperus polycarpos（K. Koch） seeds is very low and attributed to the large proportion of nonviable seeds in the seed lots.Thus, the aim of this study was to improve seed lot quality by removing nonviable seeds using two flotation techniques： incubation-drying-separation（IDS） and modified specific gravity（MSG） separation. We examined different IDS conditions（the specific incubation time, subsequent drying time and sorting media） for effectively sorting out nonviable seeds; and tested the feasibility of modified SG separation, which involved soaking seeds in water for a certain period before sorting in different concentrations of sucrose solution. Viable seeds were expected to absorb and metabolically bind more water during soaking than dead seeds could, and hence be sorted effectively depending on the viscosity of the sucrose solution. The viability of the seeds that floated or sank was determined in a topographical tetrazolium chloride（TTC） test. For the IDS trial,7 days incubation followed by 9 h of drying and sedimentation in pure water or 200 g L-1sucrose solution identified, respectively, 75 and 82 % of the seeds as viable（sunken） seeds. For the MSG trail, 77 % viable seeds were recovered in the sunken fraction when seeds were soaked for 48 h then immediately sorted in 600 g L-1sucrose solution. In both cases, the loss of viable seeds in the discarded floating fraction was only 4 %. The results demonstrate that both IDS and MSG separation techniques substantially improved seed lot viability, but MSG separation is simple and needs no modern seed handling facility, and its efficacy relies on seed mass（due to the initial soaking） and the specific density and viscosity of the flotation medium.展开更多
Objective:To develop a protocol lor breaking of seed dormancy and increasing the seed germination rate of Bunium persicum.Methods:The seeds were treated with 3.1.6.3.12.5.25.50 and 100 μmol/L of benzyl aminopurine.gi...Objective:To develop a protocol lor breaking of seed dormancy and increasing the seed germination rate of Bunium persicum.Methods:The seeds were treated with 3.1.6.3.12.5.25.50 and 100 μmol/L of benzyl aminopurine.gibberellic acid(GA,),thidiazuron(TDZ) and forchlorlenuron.Then,seeds were transferred to two different temperature conditions including room temperature(25 ℃) and chilling temperature(2-5℃).Results:The treatment of moist seeds with chilling temperature(2—5℃) broke seed dormancy and showed maximum germination,which was 54.7%after 60 d treatment.Also,the treatment of dn seeds with chilling temperature broke seed dormancy with 9.3%germination rate after 120 d.Treatment of seeds with different level of plant growth regulators showed that under moistroom condition,there was evidence ol higher and lower seed germination rate:GA,(100 μmol/L)with 46.7%and TDZ(50 μmol/L) with 6.67%respectively.In addition,the results showed that under moist-chilling condition.TDZ(6.3 μmol/L) with 53.3%seed germination rate had higher influence on breaking seed dormancy.Treatment of seeds with combination of TDZ and GA_3 under moistchilling condition revealed higher rale of breaking of seed dormancy when 6.3 μmol/L TDZ was combined with 100 μmol/L GA,.showing 93.7%genninatiou rate.Conclusions:The effect of plant growth regulators coupled with chilling temperature on breaking of seed dormancy could provide a large number of seedlings while the long juvenile time which is the next restricting factor of plantation still remained.Thus,the subsequent growth of seedlings to provide a large number of corms is necessary for successful plantation.展开更多
Dwarf mistletoes are parasitic flowering plants that infect conifers, resulting in substantial loss of growth and mortality. Recently, forest managers in Iran are contemplating whether infection of Juniperus polycarpo...Dwarf mistletoes are parasitic flowering plants that infect conifers, resulting in substantial loss of growth and mortality. Recently, forest managers in Iran are contemplating whether infection of Juniperus polycarpos C. Koch forests by dwarf mistletoe, Arceuthobium oxycedri （DC.） M. Bieb, influences tree vigor and contributes to insuffieient natural regeneration. The present study aimed at assessing the severity of infection and its impact on growth and reproductive output of./., polycar- pos. Infected and uninfected trees （n =20 each） were selected for assess- ment of diameter, height, crown area, and crown volume as well as quantity and quality of cones and seeds. The severity of infection of trees was determined by Hawksworth＇s 6-class dwarf mistletoe rating （DMR） system. The DMR system revealed that 40% of the infected sample trees were lightly infected （DMR =1-2） and 60% were moderately infected （DMR =3--4）. Growth characteristics did not differ significantly （p 〉 0.05） between infected and uninfected trees. However, moderate infec- tion affected the reproductive output of./. polycarpos by significantly （p 〈0.05） reducing the mean number of cones per unit area of the crown, increasing the number of damaged seeds, and reducing seed size and seedgermination capacity. We conclude that reproductive output of J.. poly- carpos is more sensitive than growth characters to moderate infection by juniper dwarf mistletoe, and this might partly account for poor natural regeneration.展开更多
Yellow/stripe rust caused by Puccinia striiformis is a major problem in the Middle East specially Iran. Virulence survey of cereal rust fungi have traditionally used differential host genotype and virulent physiologic...Yellow/stripe rust caused by Puccinia striiformis is a major problem in the Middle East specially Iran. Virulence survey of cereal rust fungi have traditionally used differential host genotype and virulent physiologic race 134 E 134 AT was received to evaluate the segregating lines. A set of 35 segregating lines and three additional susceptible cultivars were added, making a total of 38 eultivars-lines. Spreader plants served as a source of inoculums. The plants were evaluated after two months based on infection percentage and the disease scoring scales. The results indicated that, there are significant changes in susceptibility assessments of the segregating lines in contrast to cultivated varieties to the yellow rust P. striiformis as far as the disease incidence and rust development is concerned in these experiments. The selected differential genotypes associated with various levels of resistance. The infection percentages were varied on the lines and the varieties, whereas the severity percentages were entirely different. The lowest severity is of line 38 with 34.70% and the highest in line 1 with 93.49% indicating 2.7 folds reduction in severity. For discrimination among the lines, the results on scoring scales gave distinctions of five classes of resistance, in which, the highest score is 29.93 and the lowest one 11.46. The cluster analysis showed almost similar results and confirmed, the analysis by Duncan＇s Multiple-lest rang as the above five distinctive groups.展开更多
Forests play a central role in the global carbon cycle.China's forests have a high carbon sequestration potential owing to their wide distribution,young age and relatively low carbon density.Forest biomass is an e...Forests play a central role in the global carbon cycle.China's forests have a high carbon sequestration potential owing to their wide distribution,young age and relatively low carbon density.Forest biomass is an essential variable for assessing carbon sequestration capacity,thus determining the spatio-temporal changes of forest biomass is critical to the national carbon budget and to contribute to sustainable forest management.Based on Chinese forest inventory data(1999–2013),this study explored spatial patterns of forest biomass at a grid resolution of 1 km by applying a downscaling method and further analyzed spatiotemporal changes of biomass at different spatial scales.The main findings are:(1)the regression relationship between forest biomass and the associated infuencing factors at a provincial scale can be applied to estimate biomass at a pixel scale by employing a downscaling method;(2)forest biomass had a distinct spatial pattern with the greatest biomass occurring in the major mountain ranges;(3)forest biomass changes had a notable spatial distribution pattern;increase(i.e.,carbon sinks)occurred in east and southeast China,decreases(i.e.,carbon sources)were observed in the northeast to southwest,with the largest biomass losses in the Hengduan Mountains,Southern Hainan and Northern Da Hinggan Mountains;and,(4)forest vegetation functioned as a carbon sink during 1999–2013 with a net increase in biomass of 3.71 Pg.展开更多
In this study fat-tail weight was estimated by external fat-tail dimensions. External fat-tail dimensions included upper, middle and lower width, length, length of gap, depth, upper and middle circumference recorded o...In this study fat-tail weight was estimated by external fat-tail dimensions. External fat-tail dimensions included upper, middle and lower width, length, length of gap, depth, upper and middle circumference recorded on 1,482 head of Lori-Bakhtiari lambs at 6 months. Of these about 311 lambs were slaughtered at the age of six months. Prediction equations were derived for fat-tail weight by multiple regression analyses with two methods. The results showed that the measure of middle circumference fat-tail was as most important measure in estimation of fat-tail weight. The measure of middle circumference fat-tail accounted for 76 percent of variation in fat-tail weight. The regression equations for predicting fat-tail weight using external fat-tail dimensions obtained from stepwise regression procedure can be estimated only with using from the lower width, length, middle circumference fat-tail and body weight with high acc, uracy （0.92）. Average of fat-tail weight estimated in the age of six months in lambs was 2.39 kg. The highest regression coefficient of external fat-tail dimensions on fat-tail weight observed for the length of fat-tail （0.095 kg）. Results of the present investigation showed that fat-tail weight in live sheep of Lori-Bakhtiari, could be estimated by measuring external fat-tail dimensions.展开更多
Environmental impact prediction is an important step in many environmental studies. A wide variety of methods have been developed in this concern. During this study, remote sensing images were used for environmental i...Environmental impact prediction is an important step in many environmental studies. A wide variety of methods have been developed in this concern. During this study, remote sensing images were used for environmental impact prediction in Ro-batkarim area, Iran, during the years of 2005～2007. It was assumed that environmental impact could be predicted using time series satellite imageries. Natural vegetation cover was chosen as a main environmental element and a case study. Environmental impacts of the regional development on natural vegetation of the area were investigated considering the changes occurred on the extent of natural vegetation cover and the amount of biomass. Vegetation data, land use and land cover classes (as activity factors) within several years were prepared using satellite images. The amount of biomass was measured by Soil-adjusted Vegetation Index (SAVI) and Normalized Difference Vegetation Index (NDVI) based on satellite images. The resulted biomass estimates were tested by the paired samples t-test method. No significant difference was observed between the average biomass of estimated and control samples at the 5% significance level. Finally, regression models were used for the environmental impacts prediction. All obtained regression models for prediction of impacts on natural vegetation cover show values over 0.9 for both correlation coefficient and R-squared. According to the resulted methodology, the prediction models of projects and plans impacts can also be developed for other environmental elements which may be derived using time series remote sensing images.展开更多
The GIS data of digital elevation model, topographic maps of different scales, satellite images and GPS were used to analyze the geometrical relations, bathometric properties and shape form of selected depressions on ...The GIS data of digital elevation model, topographic maps of different scales, satellite images and GPS were used to analyze the geometrical relations, bathometric properties and shape form of selected depressions on Al-Jirnaf valley. GIS was used to analyze the hydromorphometry and geometry of the depressions, these analyses explain the role of main valley’s contribution to the hydrology of the valley, then, three locations for water storage were suggested. 2D and 3D models of the sites were given, the maximum level, volume, surface area, circumference, shape factor of three supposed reservoirs calculated for different hypothetical levels of water in the reservoir, and the optimal level were determined, the maximum suggested levels are 190, 185 and 180 m, the areas are 3.25, 7.97 and 20.47 km2, the volumes are 0.0096, 0.0334 and 0.1118 km3 for the three locations respectively. This experimental procedure can be repeated in other depressions for the same purpose.展开更多
基金National Natural Science Foundation of China, No.41340016 Natural Science Foundation of Jiangsu Prov ince, China, No.BK2012731
文摘China is a disaster prone country, and a comprehensive understanding of change of disasters is very important for China＇s agricultural development. In this study, statistical tech niques and geographic information system tools are employed to quantify the main agricul ture disasters changes and effects on grain production in China during the period of 1990-2011. The results show that China＇s grain production was severely affected by disas ters including drought, flood, hail, frost and typhoon. The annual area covered by these dis asters reached up to 48.7x106 ha during the study period, which accounted for 44.8% of the total sown area, and about 55.1% of the per unit area grain yield change was caused by disasters. In addition, all of the disasters showed high variability, different changing trends, and spatial distribution. Drought, flood, and hail showed significantly decreasing trends, while frost and typhoon showed increasing trends. Drought and flood showed gradual changes and were distributed across the country, and disasters became more diversified from north to south. Drought was the dominated disaster type in northern China, while flood was the most important disaster type in the southern part. Hail was mainly observed in central and northern China, and frost was mainly distributed in southern China. Typhoon was greatly limited to the southeast coast. Furthermore, the resilience of grain production of each province was quite different, especially in several major grain producing areas, such as Shandong, Liaoning, Jilin and Jiangsu, where grain production was seriously affected by disasters. One reason for the difference of resilience of grain production was that grain production was marginalized in developed provinces when the economy underwent rapid development. For China＇s agricul tural development and grain security, we suggest that governments should place more em phasis on grain production, and invest more money in disaster prevention and mitigation, especially in the major grain producing provinces.
基金National Social Science Fund of China,No.19ZDA096National Natural Science Foundation of China,No.41971234,No.41971235+1 种基金Postgraduate Research and Practice Innovation Project of Jiangsu Province,No.KYCX21_0039Open Fund of Key Laboratory of Coastal Zone Exploitation and Protection,Ministry of Natural Resources,No.2021CZEPK07。
文摘As the world’s largest developing country,the ability of China’s agricultural resource utilization to effectively support the current and future food security goals has been affected by a variety of factors(e.g.,transformed supply channels,tightening international situation and frequent emergencies)in recent years and has attracted extensive attention from the academic community subject to multiple factors.This study uses literature review,statistical analysis,and spatial analysis methods to systematically explore China’s food security situation in the context of farmland resource constraints.It is found that the demand-side pressures such as demographic changes,social class differentiation,and dietary structure adjustments derived from economic growth and rapid urbanization have placed extremely high expectations on food supply.However,the quantitative restrictions,utilization ways,and health risks of farmland resources on the supply side constitute a huge hidden concern that affects the stability of food production.Although China’s farmland protection system is undergoing a transition from focusing on quantity management to sustainable use,the matching and coordinating demand pressure and supply capacity for food security is unbalanced.Therefore,facing uncertain future development scenarios,policymakers should focus on building a resilient space for China’s farmland protection to withstand the interference of major emergencies.The existing farmland protection space policy can be integrated by establishing a national farmland strategic reserve system(based on resilient space),and further development of targeted use control measures for zoning,grading,and classification will help realize sustainable China’s farmland resources use.
基金National Basic Research Program of China, No.2011CB952001 National Natural Science Foundation of China, No .41340016
文摘This research reconstructs China＇s provincial farmland dataset in the last 300 years （1661-1985） by applying factor correction, citing replacement, linear interpolation, cohesion and contrast, man-land relationship test, farming trend test, provincial administrative area adjustment, etc. on available farmland data based on China＇s current provincial administrative boundary. Based on this dataset, a quantitative analysis has been applied to study the farm- land amount and its change Characteristics at both national and provincial level. Three con- clusions are derived： （1） Along with the rapid population growth, national farmland amount has increased by about 320% in the last 300 years from 424,480 km2 in the early Qing Dy- nasty to 1,368,600 km2 in 1985. Comparing with global and national farmland datasets, in terms of the overall trend of national farmland growth, very low deviation exists but significant variances do appear for some provinces. （2） At the beginning of the Qing Dynasty, China＇s farming activities mainly existed in the Yangtze River Plain, the North China Plain, the Guanzhong Basin and the Yinchuan Plain. Thereafter, reclamation activities expanded to outer agricultural areas. Regarding of the growth rate, national farmland increase can be divided into five phases. National policy, disasters, wars, and economic development, are the main factors affecting farmland changes. （3） Significant regional variances exist in farmland changes. In the space shaped by the average farmland amount and the average annual change rate of farmland, the nation can be divided into six areas.
基金National Natural Science Foundation of China,No.41971234,No.41971235Project of Graduate Student Innovative and Practical Research in Jiangsu Province,No.KYCX20-0028Major Program of National Social Science Foundation of China,No.19ZDA096。
文摘Systematically revealing the impact of cultivated land fragmentation(CLF)on the geographical agglomeration pattern of agricultural specialization(AS)has positive significance for national agricultural production management.Based on the data of the second national land survey and agricultural production,this study has explored the impact of CLF on spatial heterogeneity of agricultural agglomeration in China by comprehensively using the Theil index,ordinary least square model and geographically weighted regression.Results showed that:(1)the regional differentiation of the CLF in China is obvious,and the cultivated land fragmentation index is generally characterized by increasing pattern from northwest to southeast.(2)Spatially,the development level of AS in China has formed three high-value clusters in the Northeast China Plain,the Qinghai-Tibet Plateau,and the middle of the Middle-lower Yangtze Plain;and the low-value contiguous areas centered on the Yunnan-Guizhou Plateau and the Sichuan Basin and surrounding regions,with significant spatial differences.The contribution of grain crops,economic crops,and vegetables and melon to the level of AS was 74.63%,9.09%,and 16.28%,respectively,and the pattern of agricultural geographical aggregation dominated by grain crops has primarily taken in shape.(3)CLF is significantly negatively correlated with AS,and every 1%increase in the degree of CLF will result in a decrease of about 0.2%in AS.However,the impact of CLF on the geographic agglomeration of different crop categories or groups varies significantly.Among them,CLF has a prominent impact on the specialization level of grain crops and vegetables and melon.Each 1%increase in the CLF will reduce the specialization level of grain crops by 0.38%,and increase the level of vegetables and melon by about 0.22%.(4)According to the landscape characteristics of cultivated land,the degree of spatial division and agglomeration of cultivated land patches have a significant impact on the formation of geographical agglomerationpattern of AS,and the intensity and direction of influence show significant regional differentiation,while the patch size has no significant impact.
文摘Detailed soil surveys involve costly and time-consuming work and require expert knowledge. Since soil surveys provide information to meet a wide range of needs, new methods are necessary to map soils quickly and accurately. In this study, multilayer perceptron artificial neural networks(ANNs) were developed to map soil units using digital elevation model(DEM) attributes. Several optimal ANNs were produced based on a number of input data and hidden units. The approach used test and validation areas to calculate the accuracy of interpolated and extrapolated data. The results showed that the system and level of soil classification employed had a direct effect on the accuracy of the results. At the lowest level, smaller errors were observed with the World Reference Base(WRB)classification criteria than the Soil Taxonomy(ST) system, but more soil classes could be predicted when using ST(7 soils in the case of ST vs. 5 with WRB). Training errors were below 11% for all the ANN models applied, while the test error(interpolation error) and validation error(extrapolation error) were as high as 50% and 70%, respectively. As expected, soil prediction using a higher level of classification presented a better overall level of accuracy. To obtain better predictions, in addition to DEM attributes, data related to landforms and/or lithology as soil-forming factors, should be used as ANN input data.
基金National Natural Science Foundation of China,No.41671082
文摘This study is proposed to reconstruct a high-resolution spatial distribution of historical land use pattern with all land use types to overcome low-accuracy and/or the monotonic land use type in current historical land use reconstruction studies. The year of 1820 is set as the temporal section and the administrative area of Jiangsu Province is the study area. Land use types being reconstructed include farmland, residential land （including both urban land and rural residential land）, water body, and other land （including forest land, grassland, and unused land）. Data sources mainly refer to historical documents, historical geographic research outcomes, contemporary statistics, and natural environmental data. With great considerations over regional natural resources and social and economic conditions, a few theoretical assumptions have been proposed to facilitate the adjustment on prefecture farmland, urban land, and rural residential land. Upholding the idea that the contemporary land use pattern has been inherently in sequence with the historical land use pattern as well as the land use pattern shall be consistent to its accessibility, this study reconstructs the land use pattern in Jiangsu Province in 1820 with 100 m＊100 m grids based on accessibility analysis and comprehensive evaluation. The outcome has been tested as valid by regionalization and correlation analysis. The resulted spatial distribution shows that back in 1820 in Jiangsu Province： （1） farmland, urban land, rural residential land, water body, and other land take about 48.49%, 4.46%, 0.16%, 15.03%, and 31.86% of the total land area respectively; （2） the land use pattern features high proportion of land in farming while low-proportion land in non-farming uses while population, topography, and the density of water body lead to great spatial variations; and （3） the reconstruction methodology has been tested as reasonable based on significant positive correlations between 1820 data and 1985 for both farmland and rural residential land at the prefecture level.
基金National Natural Science Foundation of China, No.41340016, No.41671082
文摘Land cover is the most evident landscape signal to characterize the influence of human activities on terrestrial ecosystems. Since the industrial revolution, the expansion of construction land has profoundly changed the status of land use coverage and changes. This study is proposed to reconstruct the spatial pattern of construction land （urban construction land and rural settlement land） for five historical periods over the past 200 years in Jiangsu Province with 200 m × 200 m grids on the basis of quantitative estimation. Urban construction land is estimated based on data about city walls, four gates along walls, and other socio-economic factors. Rural settlement land is calculated based on the rural population and per capita housing allowance. The spatial pattern of historical construction land is simulated based on the distribution of modern construction land in 1985 with a quantitative-boundary- suitability control method and thorough consideration over connectivity of different land use types. The study concludes that： （1） the amount of construction land in Jiangsu Province is estimated at 963.46 km^2 in 1820, 1043.46 km^2 in 1911, 1672.40 km^2 in 1936, 1980.34 km^2 in 1952 and 10,687.20 km^2 in 1985; and （2） the spatial distribution of construction land features the great proclivity to water bodies and main roads and the strong polarization of existent residence. The results are verified directly and indirectly by applying the trend verification of construction land changes and patterns, the correlation analysis between rural settlement land and local arable land, and quantitative accuracy test of the reconstructed construction land to actual historical survey maps covering four sample regions in 1936.
文摘Changes in groundwater level in Homand-Absard plain, located in north-west of Kavir-e-Markazi watershed and east of Tehran province, were studied. The used research method was descriptive approach, and the research study was conducted based on field and desk surveys. The data needed was provided from field surveys, contours maps, and data of observation wells. There were 17 observation wells in the study area where the changes in groundwater levels were measured during 1996-2013, and an index hydrograph was prepared for the aquifer of plain. The sharpest decline in the groundwater level was in the central of Homan-Absard plain. There was 1.43 m decline in the groundwater level of aquifer annually, compared with similar studies in other parts of Iran, it has a high rate, and to the average, the groundwater level of plain has dropped equal to 25.76 m, 1996-2013. According to the study findings, the groundwater level changes with those in rainfall weren't match and the drop in groundwater level during wet years and then has continued which represents the high water extraction factor on the groundwater level drop.
文摘In this study, data of body weight at slaughter （SW; n = 465）, hot carcass weight （HCW; n = 465）, cold carcass weight （CCW; n = 401）, carcass lean weight （CLW; n = 314）, carcass bone weight （CBW; n = 401）, carcass total fat weight （CTFW; n = 314） and fat-tail weight （FTW; n = 401） in Lori-Bakhtiari sheep were measured to determine their possible use in breeding programmers aimed at improving ability to carcass quality in this breed. Lambs were slaughtered at 195 ＋ 27 days of age. The method of slaughtering and cultting was Iranian cutting approach. SAS procedures were used for the statistical analysis. Means and their respective standard deviations for SW, HCW, CCW, CLW, CBW, CTFW and FTW were 45.41 ± 6.86, 22.81 ± 4.32, 22.53 ± 4.18, 11.14 ± 1.71, 3.47 ± 0.43, 7.19 ± 2.42 and 3.65 ± 1.37 kg, respectively. The coefficients of variation for CTFW and FTW were 33.62 percent and 38.01 percent, respectively. Environmental effects of kind of rearing after weaning and type of birth on HCW, CCW, CLW, CTFW and FTW traits were significant. Consequently, considerable variation exists for carcass composition traits, especially for carcass fat and fat-tail.
文摘This study was carried out during 2007-2009 in the vineyards of Ardebil province of lran to study the biology and the epidemiology of Uncinula necator--the causal agent of grape powdery mildew disease. The study concentrated on the survival and the initiation of primary inoculum of the fungal causal agent. Results of histopathological experiments indicated that U. necator survived as mycelium in the dormant buds of the grapes during winter season. Results of study on the effect of environmental factors on fungus biology showed that the pathogenic activity of the fungus began when the temperature was between 16-19 ℃ with a relative humidity more than 50%. It was also found that optimum temperature and relative humidity for the sporulation of U.necator was 20-25 ~C and 50%-100% respectively. According to the results, fungal conidia were trapped during formation of 5-6 true leaves and first disease symptoms were observed on the clusters on late June after fruit formation. Fungal cleistothecia were observed abundantly at the end of season on the leaves, petioles and twigs but they were not able to survive during winter. Formation of ascospores on young leaves was proved but their role as the primary inoculum was not supported by the results of this study. Results of this study and the new findings on the biology and epidemiology of U.necator may be of national and international interests for the management of powdery mildew disease which is one of the most destructive diseases around the world including Iran.
基金financially supported by the Iranian government scholarship program
文摘The germination of freshly collected Juniperus polycarpos（K. Koch） seeds is very low and attributed to the large proportion of nonviable seeds in the seed lots.Thus, the aim of this study was to improve seed lot quality by removing nonviable seeds using two flotation techniques： incubation-drying-separation（IDS） and modified specific gravity（MSG） separation. We examined different IDS conditions（the specific incubation time, subsequent drying time and sorting media） for effectively sorting out nonviable seeds; and tested the feasibility of modified SG separation, which involved soaking seeds in water for a certain period before sorting in different concentrations of sucrose solution. Viable seeds were expected to absorb and metabolically bind more water during soaking than dead seeds could, and hence be sorted effectively depending on the viscosity of the sucrose solution. The viability of the seeds that floated or sank was determined in a topographical tetrazolium chloride（TTC） test. For the IDS trial,7 days incubation followed by 9 h of drying and sedimentation in pure water or 200 g L-1sucrose solution identified, respectively, 75 and 82 % of the seeds as viable（sunken） seeds. For the MSG trail, 77 % viable seeds were recovered in the sunken fraction when seeds were soaked for 48 h then immediately sorted in 600 g L-1sucrose solution. In both cases, the loss of viable seeds in the discarded floating fraction was only 4 %. The results demonstrate that both IDS and MSG separation techniques substantially improved seed lot viability, but MSG separation is simple and needs no modern seed handling facility, and its efficacy relies on seed mass（due to the initial soaking） and the specific density and viscosity of the flotation medium.
基金Supported by Universiti Putra Malaysia.the project via Research University Grant Scheme(RUGS)(Vote No.9322400)
文摘Objective:To develop a protocol lor breaking of seed dormancy and increasing the seed germination rate of Bunium persicum.Methods:The seeds were treated with 3.1.6.3.12.5.25.50 and 100 μmol/L of benzyl aminopurine.gibberellic acid(GA,),thidiazuron(TDZ) and forchlorlenuron.Then,seeds were transferred to two different temperature conditions including room temperature(25 ℃) and chilling temperature(2-5℃).Results:The treatment of moist seeds with chilling temperature(2—5℃) broke seed dormancy and showed maximum germination,which was 54.7%after 60 d treatment.Also,the treatment of dn seeds with chilling temperature broke seed dormancy with 9.3%germination rate after 120 d.Treatment of seeds with different level of plant growth regulators showed that under moistroom condition,there was evidence ol higher and lower seed germination rate:GA,(100 μmol/L)with 46.7%and TDZ(50 μmol/L) with 6.67%respectively.In addition,the results showed that under moist-chilling condition.TDZ(6.3 μmol/L) with 53.3%seed germination rate had higher influence on breaking seed dormancy.Treatment of seeds with combination of TDZ and GA_3 under moistchilling condition revealed higher rale of breaking of seed dormancy when 6.3 μmol/L TDZ was combined with 100 μmol/L GA,.showing 93.7%genninatiou rate.Conclusions:The effect of plant growth regulators coupled with chilling temperature on breaking of seed dormancy could provide a large number of seedlings while the long juvenile time which is the next restricting factor of plantation still remained.Thus,the subsequent growth of seedlings to provide a large number of corms is necessary for successful plantation.
基金supported by the Iran Government Science and Technology Scholarship Program
文摘Dwarf mistletoes are parasitic flowering plants that infect conifers, resulting in substantial loss of growth and mortality. Recently, forest managers in Iran are contemplating whether infection of Juniperus polycarpos C. Koch forests by dwarf mistletoe, Arceuthobium oxycedri （DC.） M. Bieb, influences tree vigor and contributes to insuffieient natural regeneration. The present study aimed at assessing the severity of infection and its impact on growth and reproductive output of./., polycar- pos. Infected and uninfected trees （n =20 each） were selected for assess- ment of diameter, height, crown area, and crown volume as well as quantity and quality of cones and seeds. The severity of infection of trees was determined by Hawksworth＇s 6-class dwarf mistletoe rating （DMR） system. The DMR system revealed that 40% of the infected sample trees were lightly infected （DMR =1-2） and 60% were moderately infected （DMR =3--4）. Growth characteristics did not differ significantly （p 〉 0.05） between infected and uninfected trees. However, moderate infec- tion affected the reproductive output of./. polycarpos by significantly （p 〈0.05） reducing the mean number of cones per unit area of the crown, increasing the number of damaged seeds, and reducing seed size and seedgermination capacity. We conclude that reproductive output of J.. poly- carpos is more sensitive than growth characters to moderate infection by juniper dwarf mistletoe, and this might partly account for poor natural regeneration.
文摘Yellow/stripe rust caused by Puccinia striiformis is a major problem in the Middle East specially Iran. Virulence survey of cereal rust fungi have traditionally used differential host genotype and virulent physiologic race 134 E 134 AT was received to evaluate the segregating lines. A set of 35 segregating lines and three additional susceptible cultivars were added, making a total of 38 eultivars-lines. Spreader plants served as a source of inoculums. The plants were evaluated after two months based on infection percentage and the disease scoring scales. The results indicated that, there are significant changes in susceptibility assessments of the segregating lines in contrast to cultivated varieties to the yellow rust P. striiformis as far as the disease incidence and rust development is concerned in these experiments. The selected differential genotypes associated with various levels of resistance. The infection percentages were varied on the lines and the varieties, whereas the severity percentages were entirely different. The lowest severity is of line 38 with 34.70% and the highest in line 1 with 93.49% indicating 2.7 folds reduction in severity. For discrimination among the lines, the results on scoring scales gave distinctions of five classes of resistance, in which, the highest score is 29.93 and the lowest one 11.46. The cluster analysis showed almost similar results and confirmed, the analysis by Duncan＇s Multiple-lest rang as the above five distinctive groups.
基金supported by the National Key Research and Development Program of China(2019YFA0606603)the National Natural Science Foundation of China(No.41971234)the Project of Graduate Student Innovative and Practical Research in Jiangsu Province(KYCX20-0028)。
文摘Forests play a central role in the global carbon cycle.China's forests have a high carbon sequestration potential owing to their wide distribution,young age and relatively low carbon density.Forest biomass is an essential variable for assessing carbon sequestration capacity,thus determining the spatio-temporal changes of forest biomass is critical to the national carbon budget and to contribute to sustainable forest management.Based on Chinese forest inventory data(1999–2013),this study explored spatial patterns of forest biomass at a grid resolution of 1 km by applying a downscaling method and further analyzed spatiotemporal changes of biomass at different spatial scales.The main findings are:(1)the regression relationship between forest biomass and the associated infuencing factors at a provincial scale can be applied to estimate biomass at a pixel scale by employing a downscaling method;(2)forest biomass had a distinct spatial pattern with the greatest biomass occurring in the major mountain ranges;(3)forest biomass changes had a notable spatial distribution pattern;increase(i.e.,carbon sinks)occurred in east and southeast China,decreases(i.e.,carbon sources)were observed in the northeast to southwest,with the largest biomass losses in the Hengduan Mountains,Southern Hainan and Northern Da Hinggan Mountains;and,(4)forest vegetation functioned as a carbon sink during 1999–2013 with a net increase in biomass of 3.71 Pg.
文摘In this study fat-tail weight was estimated by external fat-tail dimensions. External fat-tail dimensions included upper, middle and lower width, length, length of gap, depth, upper and middle circumference recorded on 1,482 head of Lori-Bakhtiari lambs at 6 months. Of these about 311 lambs were slaughtered at the age of six months. Prediction equations were derived for fat-tail weight by multiple regression analyses with two methods. The results showed that the measure of middle circumference fat-tail was as most important measure in estimation of fat-tail weight. The measure of middle circumference fat-tail accounted for 76 percent of variation in fat-tail weight. The regression equations for predicting fat-tail weight using external fat-tail dimensions obtained from stepwise regression procedure can be estimated only with using from the lower width, length, middle circumference fat-tail and body weight with high acc, uracy （0.92）. Average of fat-tail weight estimated in the age of six months in lambs was 2.39 kg. The highest regression coefficient of external fat-tail dimensions on fat-tail weight observed for the length of fat-tail （0.095 kg）. Results of the present investigation showed that fat-tail weight in live sheep of Lori-Bakhtiari, could be estimated by measuring external fat-tail dimensions.
文摘Environmental impact prediction is an important step in many environmental studies. A wide variety of methods have been developed in this concern. During this study, remote sensing images were used for environmental impact prediction in Ro-batkarim area, Iran, during the years of 2005～2007. It was assumed that environmental impact could be predicted using time series satellite imageries. Natural vegetation cover was chosen as a main environmental element and a case study. Environmental impacts of the regional development on natural vegetation of the area were investigated considering the changes occurred on the extent of natural vegetation cover and the amount of biomass. Vegetation data, land use and land cover classes (as activity factors) within several years were prepared using satellite images. The amount of biomass was measured by Soil-adjusted Vegetation Index (SAVI) and Normalized Difference Vegetation Index (NDVI) based on satellite images. The resulted biomass estimates were tested by the paired samples t-test method. No significant difference was observed between the average biomass of estimated and control samples at the 5% significance level. Finally, regression models were used for the environmental impacts prediction. All obtained regression models for prediction of impacts on natural vegetation cover show values over 0.9 for both correlation coefficient and R-squared. According to the resulted methodology, the prediction models of projects and plans impacts can also be developed for other environmental elements which may be derived using time series remote sensing images.
文摘The GIS data of digital elevation model, topographic maps of different scales, satellite images and GPS were used to analyze the geometrical relations, bathometric properties and shape form of selected depressions on Al-Jirnaf valley. GIS was used to analyze the hydromorphometry and geometry of the depressions, these analyses explain the role of main valley’s contribution to the hydrology of the valley, then, three locations for water storage were suggested. 2D and 3D models of the sites were given, the maximum level, volume, surface area, circumference, shape factor of three supposed reservoirs calculated for different hypothetical levels of water in the reservoir, and the optimal level were determined, the maximum suggested levels are 190, 185 and 180 m, the areas are 3.25, 7.97 and 20.47 km2, the volumes are 0.0096, 0.0334 and 0.1118 km3 for the three locations respectively. This experimental procedure can be repeated in other depressions for the same purpose.
