Determinants of crop diversity in the regions of Bangladesh (1990–2008)

The paper measures the level of crop diversity and identifies factors influencing diversification using a panel data of 17 regions of Bangladesh covering a 19 year period (1990–2008). Results revealed the trends that agricultural areas allocated to high‐yielding variety rice, spices and vegetables has increased, while areas cultivating traditional rice, minor cereals, oilseeds, pulses, jute and sugarcane has declined at variable rates across regions with significant differences. The level of crop diversity is also significantly different across regions and has decreased in 2008 from its 1990 level in most regions except Faridpur, Khulna and Sylhet. Among the determinants, an increase in the relative prices of vegetables and urea fertilizer, extension expenditure, labour stock per farm, average farm size, irrigation and a reduction in livestock per farm significantly increase crop diversity. Price policies to improve vegetable prices and investment in irrigation infrastructure and extension services are suggested to promote crop diversity in Bangladesh.     

Agricultural land use dynamics in the Brazilian Amazon based on remote sensing and census data

The potential impact of deforestation in the Brazilian Amazon on greenhouse gas emissions to the atmosphere calls for policies that take account of changes in forest cover. Although much research has focused on the location and effects of deforestation, little is known about the distribution and reasons for the agricultural uses that replace forest cover. We used Landsat TM-based deforestation and agricultural census data to generate maps of the distribution and proportion of four major agricultural land uses throughout the Brazilian Amazon in 1997 and 2007. We built linear and spatial regression models to assess the determinant factors of deforestation and those major agricultural land uses - pasture, temporary agriculture and permanent agriculture - for the states of Pará, Rondônia, and Mato Grosso. The data include 30 determinant factors that were grouped into two years (1996 and 2006) and in four categories: accessibility to markets, public policies, agrarian structure, and environment. We found an overall expansion of the total agricultural area between 1997 and 2007, and notable differences between the states of Pará, Rondônia, and Mato Grosso in land use changes during this period. Regression models for deforestation and pasture indicated that determinant factors such as distance to roads were more influential in 1997 than in 2007. The number of settled families played an important role in the deforestation and pasture, the effect was stronger in 2007 than 1997. Indigenous lands were significant in preventing deforestation in high-pressure areas in 2007. For temporary and permanent agricultures, our results show that in 1997 the effect of small farms was stronger than in 2007. The mapped land use time series and the models explain empirically the effects of land use changes across the region over one decade.     

Measuring rural settlement expansion in Uzbekistan using remote sensing to support spatial planning

Population growth demands sustainable spatial planning strategies for settlements in Uzbekistan, Central Asia, especially in rural areas that are inhabited by approximately 64 percent of the country's population. Where can settlements expand in rural Uzbekistan and does settlement growth affect valuable agricultural land? SPOT-5 data with a resolution of 2.5 m was utilized for mapping building layers and assessing settlement growth between 2006 and 2011 at the example of 53 communities located in the Khorezm province in North-West Uzbekistan. Object based image analysis was conducted, i.e. a multi-scale segmentation for the derivation of building contours, followed by a random forest (RF) classification of the object's spectral and spatial characteristics. A geographical information system (GIS) was used for identifying settlement densification and expansion processes, and for quantifying agricultural land parcels of different soil quality occupied during settlement growth.A calibration routine based on indices of segmentation quality enabled the selection of optimal segmentation parameters. After GIS-based refinements of the RF classification results, the overall accuracy (OA) of the building layers of both years exceeded 95%. The OA of the change map was 92.7%. The results revealed that the building area increased by 20%, whilst settlement expansion amounted to 10% in 2006–2011. Settlements widely expanded in accordance with the existing rules prohibiting the conversion of agricultural land to housing areas. Nevertheless, about 20% of the settlement growth occurred on agricultural production areas, also on those with highly productive soils. The results indicated both, the pressure on land resources for settlement growth and – in face of continuous population growth – an increasing demand for comprehensive spatial planning in rural Uzbekistan. The elaborated methodological approach can be extrapolated to regions throughout Central Asia with similar environmental conditions.     

19802000北京市农业土地生产性的变动分析

根据1980、1990、2000年的统计资料和实地走访观察,本文分析了北京市乡镇一级的粮食作物、蔬菜作物和果品作物的分布格局及农业土地生产性近20年的变化。研究认为:1980年北京农业生产分布格局与土地生产性为比较典型的杜能模式;随着农业经营的多样化,1990年和2000年北京农业土地生产性呈现出多样的分布格局;北京粮食作物、蔬菜作物、果品作物的分布格局及农业土地生产性近20年的变化与此阶段的农业生产政策、农业以外的社会经济活动变化有较强的关联性;对北京以上问题的研究为验证杜能、辛克利亚、布莱昂特城市周边农业地域研究经典理论的演变提供了实证案例。     

Changes in crop type distribution in Zhangye City of the Heihe River Basin,China

With rapid economic development in China, crops have undergone remarkable changes in both their type and spatial pattern. Timely and accurate information of crop type distribution will help government and agricultural producers quickly understand regional agricultural production conditions to better facilitate appropriate adjustments in planting patterns and policies. Another benefit of acquiring such knowledge of crops is that it should enhance regional agricultural competitiveness, optimize resource allocations, and further guarantee national food security. Towards this end, and using the Zhangye City in the Heihe River Basin as a study area, the present research elaborated upon a methodology to classify crop type distribution based on multi-temporal Thematic Mapper and Enhanced Thematic Mapper Plus (TM/ETM+) images. Using this methodology we achieved the spatial distributions of crop types in Zhangye City in 2007 and 2012, and analyzed changes in their distributions over this period. In addition, some landscape indices were calculated to clarify the landscape pattern of crops. The crop conversion potentials in 2017 were modeled using four conversion sub-models of the Multi-Layer Perceptron (MLP) neural network. Generally, the overall accuracy of crop classification in Zhangye was high, at 89.38%. From 2007 to 2012, the cultivated land area in Zhangye increased from 463.81 × 10³ ha to 493.89 × 10³ ha. The sowing area of corn and oilseed rape increased by 39.21 × 10³ ha and 5.99 × 10³ ha, respectively, while for wheat and barley the sowing area decreased by 3.61 × 10³ ha and 9.14 × 10³ ha, respectively. Considering other crop types as a group, their sowing area decreased by only 2.37 × 10³ ha. The increase in corn sowing area mainly came from the conversion of other crops to corn, which accounted for 43.09% of its total sowing area in 2012. Furthermore, corn and oilseed rape showed a tendency of intensive sowing, whereas for wheat and barley the tendency was towards scattered sowing. For the future, corn has high conversion potential in Linze and Gaotai counties of Zhangye, while wheat, barley and oilseed rape have high conversion potentials in Minle and Shandan counties.     

Potential distributional changes of invasive crop pest species associated with global climate change

This study investigated the potential global distributional shifts of poikilothermic invasive crop pest species associated with climate change, aiming to understand if their overall global distributions will expand or contract, and how the species distributions will vary across different regions. An ecological niche modelling analysis was conducted for 76 species. The potential distributional changes of the species in 2050 and 2070 were scrutinized for two climate change scenarios, which were further examined across different temperature and precipitation ranges. Results showed that averages of the mean probabilities of presence of the 76 crop pest species were predicted to increase. Higher species turnovers were predicted mostly to occur in areas with increasing predicted species richness. Lower species turnovers, however, were predicted mostly to occur in areas with decreasing predicted species richness. Species richness increases were predicted to occur more often in currently lower temperature (annual mean temperature approximately < 21 °C) or lower precipitation (annual precipitation approximately < 1100 mm) regions. Areas with the current annual mean temperatures at around 27 °C and 7.5 °C, respectively, were predicted to experience the highest decrease and increase in species richness as the climate warms. In conclusion, climate change is likely to expand the pest species’ overall distribution across the globe. It could have more profound impacts on the species distributions of those regions where species richness increases are expected, by altering the species’ community compositions.     

Optimal spatial allocation of irrigation water under uncertainty using the bilayer nested optimisation algorithm and geospatial technology

The optimal spatial allocation of irrigation water under uncertainty has become a serious concern because of irrigation water shortage and uncertain factors that affect irrigation water allocation. In this study, an optimal multi-objective model for irrigation water allocation under uncertainty is developed to maximise the economic benefit of crops and minimise the operation cost and water deficit of crop irrigation. The original and optimal plantation structure, irrigation mode and soil water content are acquired through geospatial technology. A bilayer nested optimisation (BLNO) algorithm is designed to produce multiple individuals of design vectors using an ant colony neural network algorithm for an outer optimisation. Meanwhile, a continuous adaptive ant colony (CAAC) algorithm is used for inner optimisation to calculate the interval values of the uncertain model. The crop distribution and irrigation mode are obtained to parameterise the planting area and the water demand of each crop and each block in the multi-objective model. This model is then solved and analysed. Compared to the optimal schemes obtained from an inexact two-stage fuzzy-stochastic programming and the CAAC, respectively, BLNO can effectively and efficiently solve the optimal spatial allocation of irrigation water under uncertainty. This method can spatially maximise the economic benefit of crops and minimise the operation cost and water deficit of crop irrigation using lower and upper bound maps whilst visually obtaining the exact crop type, reasonable irrigation method and precise water demand for each block and for the entire irrigated area.     

干旱灾害对农业技术效率的影响

干旱是影响农业生产最主要的自然灾害,探究干旱灾害对农业技术效率的影响机理,明晰灌溉水平与二者之间的逻辑关系,具有重要意义。基于全国27个省份2006—2020年的面板数据,运用随机前沿生产函数（SFA）模型测算农业技术效率,探讨农业技术效率的时空分布特征。在此基础上,采用固定效应和面板门槛回归模型,验证干旱灾害、灌溉水平与农业技术效率三者之间的关系。结果表明：农业技术效率总体呈现上升趋势,年均增长率达到1.09%,技术效率空间分布存在较大差异,西北和华北农业技术效率较低,华东和华中技术效率较高。干旱灾害对农业技术效率有显著负向影响,灌溉水平有利于农业技术效率的提升。当灌溉水平超过38.88%的门槛值时,会缓解干旱灾害对农业技术效率的负向影响。     

澜沧江流域农业灌溉需水的时空变化(英文)

Based on the data of eight meteorological stations from the 1950s to 2007, current cropping patterns, field water moisture management, we use the Mann-Kendall and the Re-scaled Range Analysis methods to research the changes of humidity and crop irrigation water requirements in the Lancang River Basin. The results show that the annual and dry season average temperatures significantly increased, and the dry season rainfall increased while wet season rainfall decreased. Evaportranspiration (ET0) increased during both dry and wet seasons at all stations except Dali, Jianchuan and Gengma, and the aridity-humidity index decreased at most of the stations. The turning points of weather factors, ET0, the arid-ity-humidity index, paddy irrigation requirements and total agricultural water requirements occurred from the 1960s to the 1990s. The spatial changing tendency of paddy irrigation quota increased with the increase of altitude and latitude, and the correlation coefficients are 0.513 and 0.610, respectively. The maximum value is observed in Weixi, while the minimum in Mengla.     

Scaling Agricultural Innovations: Pigeonpea in Malawi

Successful scaling of agricultural development strategies is fundamental to increased production and yields, yet targeting efforts frequently fail to fully consider the underlying biophysical drivers of agricultural marginality, particularly at fine spatial resolutions. We present a heuristic for intelligent targeting, utilizing remotely sensed information to identify the intersection between marginal conditions for performance of a staple crop and the optimal niche for technologies that improve crop performance. Here, we explore the geographic potential of maize diversification with pigeonpea, a crop with soil productivity enhancing properties. Overall, 79 percent of agricultural land in Malawi exhibits climate conditions optimal for pigeonpea cultivation and, in total, approximately 51 percent of Malawian maize-based farming is expected to receive some benefit from pigeonpea integration, with 9 percent receiving predictable and substantial benefits. These findings illustrate the geographic scaling potential of pigeonpea in Malawi and provide direction for informed pigeonpea deployment and market development across the country.     

Remote sensing monitoring on regional crop water productivity in the Haihe River Basin

Crop water productivity （CWP） agricultural development in water scarcity is one of the important indicators for sustainable area. There is serious conflict between water sup- ply and requirement in the Haihe River Basin. CWP of winter wheat and summer maize from 2003 to 2007 in the Haihe River Basin is estimated based on large-scale evapotranspiration （ET） and crop yield obtained by remote sensing technology. Spatial and temporal distribution of CWP of winter wheat and summer maize is investigated in this study. Results show that CWP of winter wheat in most parts of the study area varies from 1.02 kg/m3 to 1.53 kg/m3, and CWP of summer maize varies from 1.31 kg/m3 to 2.03 kg/m3. Multi-year averaged CWP of winter wheat and summer maize in the study area is about 1.19 kg/m3 and 1.59 kg/m3. CWP results show certain promotion potential to alleviate the water shortage in the Haihe River Basin. Correlation analysis of CWP, crop yield and ET shows that there is great potential for crop yield promotion without the growth in irrigation water. Large-scale CWP estimated by remote sensing technology in this study shows spatial distribution features, which could be used to real-time agricultural water resource management combined with crop yield and ET.     

疏勒河流域双塔灌区种植结构变化及其原因

基于1996-2010年双塔灌区各乡（镇）农作物类型、种植面积、供水定额、用水定额、作物单产及价格等资料,探讨了气候变化背景下农业种植结构调整原因及其影响。结果表明：研究区2010年作物种植面积较1996年增长2.3倍,其中粮食作物种植面积减少,经济作物和其他作物种植面积增加,农作物总产值和单位产值均明显提高,说明当地种植结构调整优化在产生经济效益方面效果明显。当地种植结构调整主要受自然条件、政策指导、历史根源、农民意愿、市场调节、灌溉供水条件等多方面因素的影响,其中自然条件中的水资源供应状况主要影响作物种植面积,其他因素影响作物种植类型。通过种植结构调整,当地农业产值在增长同时,用水紧张现象较以前有所缓解,地表水基本可以满足农田灌溉需求,减少了对地下水的使用,从而对保护当地生态具有重要意义。     

Speciation in gall-inducing thrips on Acacia in arid and non-arid areas of Australia

Habitat modification mediated by abiotic processes imposes consequences for the diversification of plants and plant specialists. Host plant diversification is expected to be dependent on environmental and ecological constraints that are fundamentally connected to physiography (physical geography). A phylogenetic approach is used to reconstruct ancestral host plant affiliation of gall-inducing thrips that specialize on Australian Acacia. Diversification rate models are applied to gall-thrips clades that are affiliated with different Acacia host lineages. Gall-thrips diversification is reconciled with contemporary patterns of species diversity relating to the different host lineages. Results indicate that diversification on host lineages that are mostly distributed in non-arid areas are best explained by a rate-constant model. However, this model disguised additive effects of rate-variable lineage accumulation that indicated diversification decreases in sub-clades within this larger group. Gall-thrips affiliated with hosts distributed mostly in arid areas were best characterized by rate-variable decreasing net diversification. The work infers parent gall-thrips lineages are less species diverse compared to daughter lineages that tend to be distributed away from the arid interior of Australia. Contrasting ecological and environmental interactions unique to parent and daughter lineages are suggested to influence the mode of speciation and phenotypic diversity represented by each.     

河南省小麦生产的区域差异及其对农用地分等的影响

河南是农业大省,粮食产量居全国首位,但全省粮食产量区域差异比较明显,豫东平原、豫北山前平原、南阳盆地为主要产粮区,而西部山区粮食生产力低下。农用地质量的优劣直接决定着粮食产量的高低,而作物的生产潜力和现实生产力影响着农用地质量的好坏。一般来说,作物生产潜力空间分布具有明显的南北纬度地带渐变规律,现实生产力则是在土地的自然属性融入社会经济因素而导致的土地投入和利用上的差异。文章以小麦为例,主要从潜在生产力和现实生产力2个方面阐述了造成小麦产量区域差异的原因并分析了它们对农用地分等产生的影响。     

特色种植的空间持续性及其影响因素研究——以河南省封丘县树莓产业为例

以河南省封丘县树莓产业为例,基于实地调查,从特色种植的空间扩散网络、村域种植规模变化、不同类型村空间分布特征、整体参与村空间集聚特征4方面对特色种植的空间持续性进行分析发现：特色种植空间扩散网络密度低,空间持续性不强,但其变化的空间范围一定,集聚特征明显。运用AMOS21.0对以上现象的影响因素进行分析发现：① 农户自身特性,尤其是冒险性精神对其持续种植时长影响较大;② 资金、技术、信息等生产条件获取越便利,农户持续种植时间越长;③ 政府推动对农户持续种植具有正向作用;④ 资源环境,尤其是土壤特性和能人带动对村域种植规模影响深刻;⑤ 距离区位对村域持续种植的影响弱于基础设施条件。     

Six decades of agricultural land use change in Bangladesh: Effects on crop diversity,productivity, food availability and the environment, 1948–2006

This paper provides a detailed analysis of agricultural land use change in Bangladesh over a 59‐year period (1948–2006) and examines how these have impacted crop diversity, productivity, food availability and the environment. The key findings of the analysis are: first, land use intensity has increased significantly over this period, mainly from the widespread adoption of a rice‐based Green Revolution technology package beginning in the early 1960s; second, contrary to expectation, crop diversity too has increased; third, although land productivity has increased significantly, declines in the productivity of fertilizers and pesticides raise doubts over sustaining agricultural growth; fourth, food availability has improved, with a reversal in the dietary energy imbalance in recent years despite a high population growth rate; and finally, the production environment has suffered with widespread soil nutrient depletion experienced in many agroecological regions. The policy implication points towards crop diversification as a desired strategy for agricultural growth to improve resource economy, productivity and efficiency in farming in Bangladesh.     

Soil salinity: A neglected factor in plant ecology and biogeography

This paper argues that soil salinity needs to be more broadly acknowledged as a driving factor in plant ecology—not only in the ecology of halophytes—in order to understand and make more accurate predictions for the impact of environmental change on biodiversity and vegetation patterns throughout the semi-arid world. It summarizes recent research on soil salinity and plant distributions in semi-arid environments throughout the world: there is empirical as well as experimental evidence that soil salinity, even at low levels, is an abiotic stress factor that influences vegetation patterns and diversification. Lines of evidence demonstrating salinity's potential influence as a selective agent in East Africa and North America are presented. The paper then synthesizes recent results from spatial ecology, plant and insect systematics and behavioral ecology, focusing on Australia, that support a role for salinity in evolutionary ecology of Acacia. On a shorter time scale, soil salinity may play a role in weed invasion and woody vegetation encroachment in Australia.     

近50多年来澜沧江流域农业灌溉需水的时空变化

利用澜沧江流域云南境内8 个气象站1950s-2007 年的逐月气象数据,现状作物种植、农业耕作、田间水分管理等资料,应用Mann-Kendall 法和R/S 分析法,探索50 多年来流域区的干湿变化、农业灌溉定额转折变化趋势及分布规律。结果表明：年、季平均温度普遍地显著升高,降水量干季增加、湿季减少;大部分地区的参照作物腾发量ET0在年度及干、湿季都呈增加趋势,仅在流域中段大理、剑川、耿马的部分时段为减少,干湿指数大多数地区都是降低;水稻及农业综合灌溉需水定额从流域上游到下游逐渐呈减少、增-减并存到增加的趋势。气象因子、ET0、干湿指数、水稻灌溉及农业综合灌溉定额发生转折变异现象都集中在澜沧江中下段的耿马、思茅、景洪、勐腊等地,且时间系列的转折变异点在1960s-1990s 的各个时期均有出现。水稻灌溉定额随纬度方向变化的相关系数为0.513,随海拔高程变化为0.610,最高值出现在维西,最低值为勐腊;农业综合灌溉定额受作物种植结构和水稻种植面积的影响较大,二者相关系数达到0.826,但其与纬度、海拔的变化规律不明显,最高值在大理,最低值在维西。灌溉定额在小范围内的多样性变化,表明在纵向岭谷特殊环境对地表水汽输送、气温和气流场分布等的“通道-阻隔”作用下,澜沧江河谷农业灌溉需水量时空变化的复杂性。     

近25a来新疆农作物水足迹与经济增长的空间关系分析

水—经济空间关系是干旱区与半干旱区水资源研究的热点,揭示水—经济空间分布演变规律和因果关系,可为优化水资源合理配置、合理部署产业结构调整政策提供理论和决策参考。研究应用水足迹理论,核算新疆各地州1991—2015年农作物水足迹,结合信息熵值理论分析新疆各地州农作物水足迹、国内生产总值、第一产业增加值其熵值的空间演变规律及因果关系。结果表明：新疆农作物水足迹与第一产业增加值、国内生产总值空间演变整体向着均衡有序的方向发展,水—经济的空间不均衡性逐步缩小;新疆农作物水足迹显著影响其第一产业增加值空间演变,影响期1～5 a,农业经济空间分布受农业用水空间分布的长期制约;农作物水足迹和国内生产总值没有空间演变因果关系,全疆经济发展向着第二产业、第三产发展转型,农业经济不再显著影响全疆经济发展。     

Spatial variability of soil nutrients and GIS-based nutrient management in Yongji County,China

Integrated nutrient management is important for sustainable agricultural production and protecting environment quality and has been widely investigated around the world. In this article the spatial variability of soil nutrients was investigated and a regionalized nutrient management system was developed using geostatistics and geographic information system technologies. A total of 511 GPS-referenced soil samples were taken in Yongji County, Shanxi province, China, and analysed for major soil nutrients: soil total nitrogen (TN), Olsen extractable phosphorus (OLSENP) and extractable potassium (EXTK). Low concentrations of nitrogen (N) and phosphorus (P) were found and they are likely to be the main limiting nutrients for crop growth in this county. Within the county moderate spatial dependence was found for all three soil variables, but at different spatial scales. The spatial distributions of TN, OLSENP and EXTK were estimated by using kriging interpolation. The cropped areas of the county were divided into fertilizer management categories consisting of four classes of TN, three classes of OLSENP and two classes of EXTK. For the targeted crop yields, regionalized fertilization maps of N, P and K in the county were produced using geographic information system. In 3-year field verification trials in two villages the crop yields of the wheat–maize rotation system increased by 10–20%, and farmers' cash income increased by 1550–2610 RMB ha^?1 year^?1 where regional fertilization recommendations were implemented, in comparison with traditional farmers' practices. The regionalized maps are a practical alternative to site-specific soil nutrient management approaches in areas where it is not practical, because of small farm size or other constraints, to use intensive soil sampling and chemical analyses.