Effects of terracing and agroforestry on soil and water loss in hilly areas of the Sichuan Basin,China

Soil erosion in hilly areas of the Sichuan Basin is a serious concern over sustainable crop production and sound ecosystem. A 3-year experiment was conducted using the method of runoff plots to examine the effects of terracing and agroforestry in farmland systems on soil and water conservation of slope fields in the hilly areas in Jianyang County, Sichuan Province, Southwestern China. A power function （Y = aX^b） can statistically describe the relationship between water runoff （Y） and rainfall （X）. The regression equation for the treatment of sloping terraces with crops （Plot 2） is remarkably different from that for the treatment of sloping terraces with grasses and trees （Plot 1） and the conventional up- and down-slope crop system （Plot 3） regarding equation coefficients, while regression equations are similar between Plot 1 and Plot 3. Water runoff amount and runoff coefficient of slope fields increased by 21.5-41.0 % and 27.5 - 69.7 % respectively, compared to those of sloping terraces, suggesting that terracing notably reduced the water runoff in the field. In the case of sloping terraces, lower amount of water runoff was observed on sloping terraces with crops than on sloping terraces with grasses and trees. Sediment yields on the slope fields in the normal year of rainfall distribution were notably higher （34.41 - 331.67 % and 37.06-403.44 % for Plot 1 and Plot 2, respectively） than those on sloping terraces, implying that terracing also plays a significant role in the reduction in soil erosion. It is suggested that terracing with crops is significantly effective for soil and water conservation in cultivated farmland, while the conventional practice of up- and down- slope cultivation creates high rates of water runoff and soil sediment transport. Terracing with grasses and fruit trees shows a less reduction in water runoff than terracing with crops, which was observed in the 3-year experiments.     

水稻种植环境综合适宜性评价方法研究

开展特定区域水稻种植产业布局是科学制定区域农业种植产业规划的重要内容,而水稻种植适宜性评价是水稻种植产业布局的前提。本文以中国好粮油示范县——福建省浦城县为研究区,基于层次分析模型构建土壤条件、立地条件、灌排条件、气候条件和机械耕作条件5大类共21个指标的水稻种植适宜性评价体系,利用地学模型、回归模型和空间插值等方法计算、模拟评价指标空间分布数据,形成5 m×5 m分辨率的评价指标栅格数据集,基于经验指数法建立适宜度指数模型,开展精细尺度下的水稻种植环境综合适宜性评价。利用实测样点水稻产量与水稻种植环境综合适宜度指数进行分析,发现二者呈显著正相关,验证了本研究评价工作的正确性和可行性。最后利用K-means属性聚类法识别研究区水稻种植多维环境适宜性的空间模式。结果表明：① 研究区水稻种植高度适宜、较适宜、中度适宜耕地面积占全县耕地面积的84.4%,次适宜耕地仅占15.6%,耕地整体适宜性较高;② Ⅰ类集聚区水稻种植综合适宜性和各类指标适宜性均较高;Ⅱ类集聚区水稻种植综合适宜性较高,但灌排条件适宜性很低;Ⅲ类集聚区水稻种植综合适宜性较高,但立地、土壤条件适宜性较低;Ⅳ类集聚区水稻种植综合适宜性较低,灌排条件适宜性最低。本研究可为水稻种植适宜性评价提供方法借鉴,并为浦城县更合理科学地开展农业种植规划提供依据。     

Soil erosion control degree of the project of converting farmland to forest in mountainous areas at China��s Southwest border: A case study in Mangshi, Yunnan Province

There have been few in-depth quantitative studies on soil erosion control and the ecological effects of land use changes. Soil erosion is the first eco-environmental problem particularly in mountainous areas. A major problem in the conversion of farmland to forest is to control soil erosion and improve ecological environment and thus to improve land use sustainability. We report results of calculation and analysis on soil erosion from converted farmland parcels in city of Mangshi (near the SW frontier of China) and the surrounding areas before and after the nine-year (2000–2009) project of converting farmland to forest. There was increased water conservation effect, as a result of decreased soil erosion. The average erosion modulus of the farmland returning to eco-friendly uses decreased by 5,535.59 t/km²·a and the control degree of soil erosion modulus reached 71.00%. The increased soil erosion after the returning in the typical sample area “did not drop, but increased” as the terraced fields decreased but sloping farmland increased and yet woodland decreased.     

Soil evolution features of debris flow waste-shoal land

The reclamation and utilization of debris flow waste-shoal land plays an important role in the mitigation and control of debris flow hazards, which thus contributes a lot to the exploitation of insufficient land resources in mountainous areas and the reduction of losses caused by debris flow. The aim of this paper is to discuss the features and mechanism of soil evolution of debris flow waste-shoal land so as to search for the available modes of its reclamation and utilization. The Jiangjiagou Ravine, a typical debris flow ravine, was selected to study soil evolution features of debris flow waste-shoal land based on the analysis of soil physieochemical properties and soil microstructure. It was found that the soil evolution rates of debris flow waste-shoal land varied with different modes of reclamation. For the land which had been reclaimed for less than lO years, soil evolved most rapidly in paddy fields, and more rapidly in dry farmland than in naturally restored waste-shoal land. For the land which had been used for more than lo years, the soil evolution rates of dry farmland, naturally restored waste-shoal land and paddy farmland decreased in the file. For the same utilization period of time, significant differences were recognized in soil evolution features under different modes of reclamation. Analysis data showed that soil clay content, soil thickness, the psephicity of skeleton particles and contents of microaggregates （〈0.02 mm） in paddy farmland were all highest. Soil nutrients and porosity of dry farmland were better than those of paddy farmland and naturally restored waste-shoal land, and those of paddy farmland were superior to those of naturally restored waste-shoal land. Paddy farmland characterized by rapid pedogenesis, stable evolution and high utilizability was the priority candidate for the reclamation and utilization of debris flow waste -shoal land.     

基于Sentinel-1/2动态耦合移栽期特征的水稻种植模式识别

及时准确地获取水稻种植模式变化对于有效防控“非粮化”和完成“双碳”目标具有重要意义。现有研究多基于固定时间窗口挖掘水稻生长期特征,且多使用的是单一卫星影像数据,难以应用于大范围水稻制图。本文通过Sentinel-1/2数据构建动态窗口提取移栽期光学/雷达特征,利用其耦合关系实现水稻种植模式制图。将该算法应用于湖南和江西两省水稻制图。基于1402个地面参考点位对水稻提取结果进行验证,总体精度达92.80%;在县域尺度上,湖南和江西两省水稻制图面积与农业统计数据也具有高度一致性,R²达0.85以上。相比于用固定窗口进行水稻特征提取,该方法具有较强的鲁棒性和迁移能力,为实现更大范围作物制图提取提供新的思路和参考依据。2018—2021年江西省水稻制图结果表明,水稻总种植面积减少9.47%,约3460 km²,水稻种植强度从1.62下降至1.49;在种植模式上,“双改中”趋势明显,双季稻种植面积锐减21.61%,其中约84%改种中稻。     

Using 137Cs tracing methods to estimate soil redistribution rates and to construct a sediment budget for a small agricultural catchment in the three gorges reservoir region, China

Soil erosion and associated off-site sedimentation are threatening the sustainable use of the Three Gorges Dam.To initiate management intervention to reduce sediment yields,there is an increasing need for reliable information on soil erosion in the Three Gorges Reservoir Region(TGRR).The purpose of this study is to use 137 Cs tracing methods to construct a sediment budget for a small agricultural catchment in the TGRR.Cores were taken from a pond and from paddy fields,for 137 Cs measurements.The results show that the average sedimentation rate in the pond since 1963 is 1.50 g cm-2 yr-1 and the corresponding amount of sediment deposited is 1,553 t.The surface erosion rate for the sloping cultivated lands and the sedimentation rate in the paddy fields were estimated to be 3,770 t km-2 yr-1 and 2,600 t km-2 yr-1,respectively.Based on the estimated erosion and deposition rates,and the area of each unit,the post 1970 sediment budget for the catchment has been constructed.A sediment delivery ratio of 0.5 has been estimated for the past 42 years.The data indicate that the sloping cultivated lands are the primary sediment source areas,and that the paddy fields are deposition zones.The typical land use pattern(with the upper parts characterized by sloping cultivated land and the lower parts by paddy fields) plays an important role in reducing sediment yield from agricultural catchments in the TGRR.A 137 Cs profile for the sediment deposited in a pond is shown to provide an effective means of estimating the land surface erosion rate in the upstream catchment.     

多星数据协同的地块尺度作物分类与面积估算方法研究

为了解决多云雨地区遥感数据时空覆盖缺失的问题,以满足对地块尺度作物种植信息日益迫切的应用需求,本文在遥感图谱认知理论框架下发展了一种基于多星数据协同的地块尺度作物识别与面积估算方法。首先,基于米级高分辨率影像提取农田地块对象;其次,通过对多源中分辨率时序影像的有效化处理和指数计算,获取“碎片化”的高时空覆盖有效数据,并以地块对象为单元构建时间序列;然后,在时序分析基础上,建立多维特征空间,结合作物生长物候特征,构建决策树模型进行作物分类识别与面积计算;最后,以湖南省宁远县为研究区开展了水稻种植信息的提取实验。结果表明：本文方法可在农田地块尺度下实现不同水稻类型的准确识别及其种植面积的精细提取,早、中、晚稻的用户精度分别可达94.33%、90.76%和95.95%,总体分类精度为92.51%,Kappa系数为0.90;早、中、晚稻面积提取精度分别为93.37%、91.23%和95.42%。试验结果证明了本文方法的有效性,为其他作物种植信息的精细提取提供了借鉴。     

面向城市平原地区暴雨积涝汇水区分级划分的方法研究

汇水区划分是分布式水文模型计算的基础。针对现有方法使用DEM在平原城市地区划分的汇水区不符合实际地形情况,本文提出了一种面向城市平原地区分级划分汇水区的技术方法。该方法从城市用地分类角度出发将城市分为中心城区和郊区,依据城市排水主干水系进行汇水区一级划分,将影响中心城区和郊区的不同径流因子分别融入DEM中,利用细化的DEM进行二级汇水区划分;在此基础上,根据实际汇流情况,结合Voronoi图,对中心城区进行三级划分,最后通过GIS技术进行修正。该方法既结合了传统DEM生成子流域的算法,又融入了城市区域地物地貌特点,能更好地满足城市地区的需要。选择上海市嘉定区西北部地区为实验样区,利用该方法进行汇水区划分比较表明,其对于城市平原地区具有很好的适用性。     

Spatial and temporal patterns of soil nitrogen distribution under different land uses in a watershed in the hilly area of purple soil, China

Quantification of soil spatial and temporal variability at watershed scale is important in ecological modeling, precision agriculture, and natural resources management. The spatio-temporal variations of soil nitrogen under different land uses in a small watershed (12.10 km²) in the hilly area of purple soil at the upper reaches of the Yangtze River in southwestern China were investigated by using conventional statistics, geostatistics, and a geographical information system in order to provide information for land management and control of environmental issues. A total of 552 soil samples (0 to 15 cm) from 276 sites within the watershed were collected in April and August of 2011, and analyzed for soil total nitrogen (STN) and nitrate nitrogen (NO3-N). We compared spatial variations of STN and NO3-N under different land uses as well as the temporal variations in April (dry season) and August (rainy season). Results showed that STN contents were deeply affected by land-use types; median STN values ranged from 0.94 to 1.27 g·kg^?1, and STN contents decreased in the following order: paddy field > forestland > sloping cropland. No significant difference was found for STN contents between April and August under the same land use. However, NO3-N contents were 23.26, 10.58, and 26.19 mg·kg^?1 in April, and 1.34, 8.51, and 3.00 mg·kg^?1 in August for the paddy field, sloping cropland and forestland, respectively. Nugget ratios for STN indicated moderate spatial dependence in the paddy field and sloping cropland, and a strong spatial dependence in forestland. The processes of nitrogen movement, transformation, absorption of plant were deeply influenced by land use types; as a result, great changes of soil nitrogen levels at spatial and temporal scales were demonstrated in the studied watershed.     

精准水稻种植信息系统的分析与设计

精准农业(Precision Farming)是美国20世纪80年代初提出的农业经营概念,它的最大特点是充分考虑农田特征的空间变异,根据农田性质的空间差异对农作物实行不同的管理措施,如变量施肥、变量灌溉等,其目标是获得最大的经济收益和最少的环境污染。水稻精准种植是精准农业思想的具体实现,在实施过程中需要使用的信息包括:GPS定位信息、农田地理信息、田间采样信息、农业气象信息、作物产量信息、作物长势信息和水稻栽培专家知识等。为管理和处理这些信息并使之为水稻种植服务,水稻精准种植信息系统应当由属性数据管理、农田空间数据管理、专家系统、遥感数据处理和管理决策等子系统构成。为便于系统的开发、完善和推广,整个系统基于组件式地理信息系统开发工具,用VB编程实现。     

Synergistic effects of vegetation layers of maize and potato intercropping on soil erosion on sloping land in Yunnan Province,China

Intercropping, as an overyielding system, can decrease soil erosion on sloping land through the presence of dense canopy covers. However, the structure mechanism in canopy is still unclear. We conducted a two-year field experiment on runoff plots, exploring whether the interaction between vegetation layers reduce soil erosion in maize and potato intercropping systems. The maize, potato, and weed layers in the intercropping system were removed by a single layer, two layers and three layers, respectively(total of 8 treatments including all layers removed as the control). Then, throughfall, runoff and sediment were measured at the plot and row scale on a weekly basis. Based on the difference between each treatment and the control, we calculated and found a relative reduction of runoff and sediment by any combination of the two vegetation layers greater than the sum of each single layer. In 2016 and 2017, the highest relative reduction of runoff reached 15.65% and 46.73%, respectively. Sediment loss decreased by 33.96% and 42.77%, respectively. Moreover, runoffand sediment reduced by the combination of all vegetation layers(no layers removed) was also larger than the sum of that by each single layer. In 2016 and 2017, the highest relative reduction of runoff reached 7.32% and 3.48%, respectively. So, there were synergistic effects among multi-level(two or three layers) vegetation layers in terms of decreasing soil erosion on sloping land. Maize redistributes more throughfall at the maize intra-specific row and the maize and potato inter-specific, which is favorable for the synergistic effect of reducing soil erosion. This finding shows an important mechanism of maize and potato intercropping for soil and water conservation, and may promote the application of diverse cropping systems for sustainable agriculture in mountainous areas.     

LANDSCAPE ECOLOGICAL CONSTRUCTION IN RURAL CHINA:THEORY AND APPLICATION

1 THE STRATEGY OF ECOLOGICAL CONSTRUCTION1.1 Active Ecological BalanceThe guidelines of current ecology are changing from balance, stability, homogeneity and small scale into imbalance, instability, heterogeneity, multi-scale, and hierarchy characteristics. The so-called ecological balance means that in the relatively stable status of an ecosystem in a specific time period, material and energy input equals to their output. Also by self-adjusting, the ecosystem can rehabilita…     

平原地区基本农田土地整治景观生态规划与设计——以新泰市楼德镇基本农田土地整治项目为例

景观生态规划与设计必须在综合考虑土地整治具体工程与生态环境的基础上,合理的规避导致生态破坏的农田设计,科学规划能够促进生态系统的自身维持与修护的工程设计。该文基于农田景观规划与设计的思想,探讨了山东平原地区基本农田景观规划设计的重点,以新泰市楼德镇基本农田土地整治项目做为案例进行景观规划设计,设计内容主要包括土地平整、农田水利、田间道路、生态防护等几方面,通过探讨和摸索,为下一步土地整治规划设计和生态环境保护提供了可靠的科学依据。     

HJ卫星图像水稻种植面积的识别分析

 HJ-1A/1B卫星具有较高时空分辨率,是提取水稻等农作物种植面积的潜力数据源。本文以江汉平原腹地的监利县及周边相邻区域为研究区,根据水稻物候历,选取样区水稻生长关键期的多时相HJ-1A/1B卫星数据,利用水稻移栽期的水分信息和生长期的归一化植被指数(NDVI)变化信息,结合陆表水系数(LSWI)、短波红外波段的反射率(R_IRS-B2)、差归一化植被指数(DNDVI),构建了HJ卫星数据的水稻种植面积识别方法,提取了研究区2009-2011年水稻种植面积,得到面积精度和样本点精度均不小于90%,Kappa值不小于0.80的结果。     

Land use changes in Northeast China driven by human activities and climatic variation

Human-induced land use/cover change (LUCC) forms an important component of global environmental change. Therefore, it is important to study land use/cover and its change at local, regional and global scales. In this paper we conducted the study of land use change in Northeast China, one of the most important agricultural zones of the nation. From 1986 to 2000, according to the study results obtained from Landsat images, widespread changes in land use/cover took place in the study area. Grassland, marsh, water body and woodland decreased by 9864, 3973, 1367 and 10,052km², respectively. By comparison, paddy field, dry farmland, and built-up land expanded by 7339, 17193 and 700km², respectively. Those changes bore an interactive relationship with the environment, especially climate change. On the one hand, climate warming created a potential environment for grassland and marsh to be changed to farmland as more crops could thrive in the warmer climate, and for dry farmland to paddy field. On the other hand, the changed surface cover modified the local climate. Those changes, in turn, have adversely influenced the local environment by accelerating land degradation. In terms of socio-economic driving forces, population augment, regional economic development, and national and provincial policies were confirmed as main driving factors for land use change. Foundation item: Under the auspices of the Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-341), National Natural Science Foundation of China (No. 40871187, 40801208)     

鄱阳湖地区土地覆盖空间分布格局与景观特征分析

 鄱阳湖是我国第一大淡水湖,具有洪水调蓄、水源涵养等重要生态服务功能。掌握鄱阳湖地区土地覆盖的空间分布格局和规律,对于评价其环境保护和生态服务功能具有重要作用。本文利用环境卫星影像、2005年鄱阳湖地区土地覆盖数据,经遥感解译分析获取了鄱阳湖地区2010年土地覆盖现状数据及其空间分布格局图。研究表明:(1)采用2010年的环境星影像结合2005年土地覆盖数据,人工目视解译得到的2010年土地覆盖数据的精度为80.4%。(2)景观生态学、GIS及统计学的思想和方法可以为土地覆盖空间特征的定量分析提供技术支持。文中采用的斑块面积指数、斑块形状指数、不同土地覆盖类型的邻接指数,从不同角度反映了鄱阳湖地区土地覆盖的空间分布格局及景观特征。(3)景观指数能定量说明土地覆盖景观的形状、大小、数量和空间组合,能反映景观的生态环境特点、人类活动及社会经济状况。面积特征指数显示研究区农村聚落的离散度及破碎度最高;斑块形状指数反映出研究区水体形状趋于规则化,其受到人类的"围湖造田,围湖造地"及防洪工程建设的干扰。(4)不同土地覆盖类型的邻接指数能定量说明相邻类型在物质交换、结构与功能的相互影响及土地资源形成机制、演替过程等。水田与常绿阔叶林的邻接关系反映了人类"毁林开荒"活动对林地与水田演替关系的影响;水田与农村聚落的邻接关系,表明研究区耕地保护的重点是城镇及农村周边耕地的保护;城镇建设用地的邻接关系表明了人类生活所需的生活条件,为"移民建镇"工程提供了科学依据。分析认为:鄱阳湖地区是以耕地为主的农业区,并且有丰富的水资源及森林资源,但今后要重视农村土地的集约化利用、水资源保护、耕地资源保护和自然资源的合理开发利用。     

Effect of Wetland Reclamation on Soil Organic Carbon Stability in Peat Mire Soil Around Xingkai Lake in Northeast China

Content and density of soil organic carbon(SOC) and labile and stable SOC fractions in peat mire soil in wetland, soybean field and rice paddy field reclaimed from the wetland around Xingkai Lake in Northeast China were studied. Studies were designed to investigate the impact of reclamation of wetland for soybean and rice farming on stability of SOC. After reclamation, SOC content and density in the top 0–30 cm soil layer decreased, and SOC content and density in soybean field were higher than that in paddy field. Content and density of labile SOC fractions also decreased, and density of labile SOC fractions and their ratios with SOC in soybean field were lower than that observed in paddy field. In the 0–30 cm soil layer, densities of labile SOC fractions, namely, dissolved organic carbon(DOC), microbial biomass carbon(MBC), readily oxidized carbon(ROC) and readily mineralized carbon(RMC), in both soybean field and paddy field were all found to be lower than those in wetland by 34.00% and 13.83%, 51.74% and 35.13%, 62.24% and 59.00%, and 64.24% and 17.86%, respectively. After reclamation, SOC density of micro-aggregates( 0.25 mm) as a stable SOC fraction and its ratio with SOC in 0–5, 5–10, 10–20 and 20–30 cm soil layers increased. SOC density of micro-aggregates in the 0–30 cm soil layer in soybean field was 50.83% higher than that in paddy field. Due to reclamation, SOC density and labile SOC fraction density decreased, but after reclamation, most SOC was stored in a more complex and stable form. Soybean farming is more friendly for sustainable SOC residence in the soils than rice farming.     

A Preliminary study on traditional level-trench method to prevent rill initiation in the Three Gorges region, China

The level-trench method is a traditional tillage operation to develop a drainage system on slope land in the Three Gorges region.Before crops are planted,farmers prepare the land with level trenches spaced 3-10 m apart,depending on the slope gradient:steeper slopes require shorter distances.Little scientific analysis has been done on the use of traditional level trenches for soil conservation.We conducted a field investigation and simulation experiments,and present a comparison between the spacing of level trenches and the slope length required for rill initiation.The results indicate that the spacing of level trenches in farmland is close to the slope length required for rill initiation in the experimental plots,and regression models of trench spacing with the gradient and the slope length required for rill initiation with the gradient have similar formats;the coefficients of determination (R2) for the two equations are 0.99 and 0.88,respectively.There were some differences between the field survey and experiments,but we conclude that the traditional level-trench method has an important role in preventing rill initiation.     

精准水稻种植信息系统结构、管理与应用

精准农业是当今世界农业发展的新潮流 ,中国 2 1世纪农业的发展方向之一。稻谷产量占我国粮食总产量的 4 0 %左右 ,实现精准水稻种植具有重大意义。在上海市农工商现代化农业园区“精准农业试验与示范基地”开展的水稻精准种植试验 ,结果与其他地块相比较 ,化肥使用量减少 1 5 % ,单产提高 8% ,总收益提高 1 8%。精准水稻种植信息系统是实现水稻精准种植的核心 ,目前完成 PRC/ INFO1 .0版本的开发 ,本文介绍了系统的结构、功能和技术特点。     

Changes of soil labile organic carbon in different land uses in Sanjiang Plain,Heilongjiang Province

In the Sanjiang Plain,Northeast China,the natural wetland is undergoing a rapid conversion into agricultural land,which has resulted in drastic ecological changes in the region. To investigate the effects of different land uses on soil labile organic carbon,soils of Calamagrostis angustifolia wetland,Carex lasiocarpa wetland,dry farmland,paddy field,forest land and abandoned cultivated land were collected for measuring the contents of soil microbial biomass carbon (MBC),dissolved organic carbon (DOC),readil...