长时序海量土地利用时空数据统计优化方法     

郜允兵  张翼鹏  高秉博  潘瑜春  张晓东 《农业机械学报》2015,46(S1):290-296

针对任意查询区域年度现状地类面积统计困难、长时序变更流量分析计算耗时等问题,提出基于时空变化图模型的统计优化方法。运用图的连通性原理,对查询统计区域内和边界处的要素实体进行分类,实现了时序快照统计优化算法,解决了任意查询区域时点现状统计困难的问题,提高了时序快照统计的效率。运用多商品流原理进行时空网络图约化性判定,实现了变更流量统计优化算法,减少了要素空间叠置分析次数,解决了长时序土地利用变化变更流量统计耗时问题,提高了统计的效率。最后,以2009—2012年琼海市土地利用数据为例,进一步验证优化算法的有效性和可行性。  相似文献   

Combining deliberative and computer-based methods for multi-objective land-use planning     

K.B. Matthews  K. Buchan  A.R. Sibbald  S. Craw 《Agricultural Systems》2006

This paper reports the outcomes of a deliberative workshop comparing land-use plans proposed by land-manager or domain experts with those derived using a computer-based decision support system (DSS). The DSS integrates four main components, a geographic information system, land-use systems simulation models, impact assessments and land-use planning tools. The land-use planning tools draw on the other components to generate and evaluate alternative patterns of land use and management. Since the land-use planning tools are based on multi-objective genetic algorithms (mGAs) it is possible to generate a range of alternative plans that define the structure of the trade-off between the objectives. The workshop tasked the delegates with specifying land-use plans that achieved the best compromise between two objectives known to be non-commensurable and conflicting. The nature of the best compromise was dependent on their individual perspectives. The delegates proposed allocations both as individuals and in researcher-facilitated sub-groups. The mGA allocations were then compared with those derived by delegates and were found to be broadly similar in performance. Differences in the range of allocations considered feasible were explained by the hard and soft constraints on allocations agreed between the delegates and articulated within the workshop process. The hypothesis that part of the difference in performance between the mGA and delegate allocations was due to the delegates blocking together fields with the same land use for convenience of management was proved. The analysis of the group allocations revealed that the decision-making process had failed to improve on the individual allocations. From these results it was concluded that there was a potential role for mGA based land-use planning tools in researching into, and deliberating on, the possible impacts of policy or other factors affecting land-use systems. It was further concluded that the tools should not be used in isolation since there was the need for stake-holder inputs to adequately define the range of feasible and practical land-use plans.  相似文献   

A tool for community-based assessment of the implications of development on water security in hillside watersheds   总被引：1，自引：0，他引：1  

J. C. Luijten  E. B. Knapp  J. W. Jones 《Agricultural Systems》2001,70(2-3):603-622

Development and population growth in Latin American countries with steep slope farming are likely to further increase pressures on water and land resources. A methodology was developed for assessing water availability and use under different development pathways at a watershed scale to determine whether water security is a potential problem, and if so, under what conditions it is likely to occur. This methodology makes use of a GIS-based spatial water budget model for simulating stream water availability, water use and stream flow control on a daily basis at a watershed scale. Here, we analysed water availability under three plausible development scenarios for the 3246 ha Cabuyal River watershed in southwest Colombia in the year 2025: Corporate Farming (CF), Ecological Watershed (EW), and Business as Usual (BU). Simulated average river flows at the watershed outlet were, respectively, 874, 796 and 925 l s⁻¹ for the CF, EW and BU scenarios. The contribution of base flow to river flow (base flow index) was on average, 80.8, 85.6 and 77.9%, respectively, for the three scenarios. The watershed had the potential to meet the anticipated increase in water use under each explorative scenario. However, dams were necessary to store irrigation water in the CF scenario, otherwise over 60% of the available water would have been used during the dry season. Such a high figure raises concerns about effects on aquatic and riparian ecology, concentrations of potential contaminants, water reserves for especially low rainfall years, and the watershed resilience to meet temporarily higher water needs during the day. Analyses indicated that current water-use conflicts in the watershed can be resolved if irrigation water supply is separated from drinking water supply. This study helped reduce some of the complexity associated with the interdependencies between land and water resources, the impact of using them, and spatial linkages within the watershed. Results of this study can be used for teaching local stakeholders about basic landscape responses and helping multi-institutional alliances to become proactive and to guide development to the benefit of local communities.  相似文献   

Microsatellite Marker Based Assessment of Genetic Diversity among Cultivars, Landraces and Wild Relatives in Rice     

India being the primary center of origin for rice had a very large treasure of local land races  most of which are out of cultivation today. The exact genetic potential  their differences from commercial varieties  the magnitude of heterogeneity still present in them are not well catalogued. Hence the need to characterize the available land races has become imminent in the modem day concept of crop improvement 《分子植物育种》2007,5(2):257-258

India being the primary center of origin for rice had a very large treasure of local land races, most of which are out of cultivation today. The exact genetic potential and their differences from commercial varieties and the magnitude of heterogeneity still present in them are not well catalogued. Hence the need to characterize the available land races has become imminent in the modem day concept of crop improvement （Rezai and Frey, 1990）. The present study addresses the utility of SSR markers in divulging the genetic relationships at molecular level among the major component factions office gennplasm viz., local cultivars, land races and wild species collected from a wide range of agro-geographical regions of Indian subcontinent.  相似文献   

黄土丘陵区丰水年产流产沙特征分析     

张勇  李彦军  杜轶 《农学学报》2021,11(5):51-56

设置标准径流小区进行长期定位监测,探讨天然降雨条件下,流域内不同土地利用方式对坡面产流产沙的影响,以期为该流域土地利用规划、水土流失综合治理、生态环境改善提供理论依据.基于汾河上游阳坡小流域内2种坡度、6种不同土地利用方式的8个径流小区,开展自然降雨观测、径流泥沙观测.结果表明:(1)试验期降雨超过多年同期平均雨量,属...  相似文献   

黄河三角洲不同土地利用方式对土壤的改良效应     

刘庆  吕振江  郑文爽  张银君 《土壤通报》2011,(2):262-266

通过对黄河三角洲地区棉田、果园、林地和荒地4种不同土地利用方式下土壤样品的采集与理化指标的分析,研究了该区域不同土地利用方式对轻度盐渍化土壤的改良功能。结果显示:果园土壤的容重、pH值和全盐含量等物理性状要优于其它3种用地方式;棉田土壤有机质与全N、全P和全K含量超过果园与林地土壤,而速效N和速效P含量以果园土壤最高,速效K含量以棉田最高,果园土壤最低;果园土壤C/N比值明显高于其它3种用地方式,以荒地土壤的C/N比值最低。综合分析认为:种植果树对土壤的物理性状改良效果较好,种植棉花对土壤的化学性状具有较好的改良效果。  相似文献   

Land-use history has a stronger impact on soil microbial community composition than aboveground vegetation and soil properties     

Kamlesh Jangid  Mark A. Williams  Thomas M. Schmidt  William B. Whitman 《Soil biology & biochemistry》2011,43(10):2184-2193

The response of soil microbial communities following changes in land-use is governed by multiple factors. The objectives of this study were to investigate (i) whether soil microbial communities track the changes in aboveground vegetation during succession; and (ii) whether microbial communities return to their native state over time. Two successional gradients with different vegetation were studied at the W. K. Kellogg Biological Station, Michigan. The first gradient comprised a conventionally tilled cropland (CT), mid-succession forest (SF) abandoned from cultivation prior to 1951, and native deciduous forest (DF). The second gradient comprised the CT cropland, early-succession grassland (ES) restored in 1989, and long-term mowed grassland (MG). With succession, the total microbial PLFAs and soil microbial biomass C consistently increased in both gradients. While bacterial rRNA gene diversity remained unchanged, the abundance and composition of many bacterial phyla changed significantly. Moreover, microbial communities in the relatively pristine DF and MG soils were very similar despite major differences in soil properties and vegetation. After >50 years of succession, and despite different vegetation, microbial communities in SF were more similar to those in mature DF than in CT. In contrast, even after 17 years of succession, microbial communities in ES were more similar to CT than endpoint MG despite very different vegetation between CT and ES. This result suggested a lasting impact of cultivation history on the soil microbial community. With conversion of deciduous to conifer forest (CF), there was a significant change in multiple soil properties that correlated with changes in microbial biomass, rRNA gene diversity and community composition. In conclusion, history of land-use was a stronger determinant of the composition of microbial communities than vegetation and soil properties. Further, microbial communities in disturbed soils apparently return to their native state with time.  相似文献   

重庆市永川区耕地地力评价结果及其利用对策     

苏音贵  邓世友  黄秀芬  唐科明  吴修煌  夏丽 《南方农业》2011,(5)

将重庆市永川区耕地地力划分为5个等级,归入全国耕地地力等级体系相应为四、五、五、六、七等,表明全区耕地土壤地力水平在全国耕地地力等级体系中属于中等偏下水平,明晰了全区耕地生产潜能,为完善种植业区域划分,优化资源配置,加速农业结构调整奠定基础。通过土样检测汇总分析,查明自1982年第二次土壤普查以来,永川区耕地土壤呈现酸化现象较重,有机质和碱解氮含量虽有所提高、但仍处于三级中等偏下的较低水平,有效磷和速效钾含量下降、且处于三至四级中等偏下水平,尤其是速效钾含量处于极度缺乏状态。  相似文献   

Relative abundance and activity of melanized hyphae in different soil ecosystems     

Annemieke van der Wal  Jaap Bloem  Wietse de Boer 《Soil biology & biochemistry》2009,41(2):417-419

Here we report on the frequency of melanized fungal hyphae in 323 soils, covering different land use types. The proportion of total hyphae that was melanized averaged 61%. Arable fields with loamy sand, heathlands and city parks on sandy soils had the highest percentage of melanized hyphae. In addition to the frequency determinations, a microcosm study was performed on the role of melanized hyphae in two different ecosystems: an ex-arable field and a forest. Melanized hyphae appeared to be part of the active hyphae in the forest soil but not in the ex-arable soil. In conclusion, our results indicate that (1) melanized hyphae represent a large proportion of the total fungal biomass in soils and that (2) their function might differ between ecosystems.  相似文献   

Conversion of a tropical forest into agroforest alters the fine root-related carbon flux to the soil     

Dietrich Hertel  Marieke A. Harteveld  Christoph Leuschner 《Soil biology & biochemistry》2009,41(3):481-490

Large areas of remaining tropical forests are affected by anthropogenic disturbances of various intensities. These disturbances alter the structure of the forest ecosystem and consequently its carbon budget. We analysed the role of fine root dynamics in the soil carbon budget of tropical moist forests in South-east Asia along a gradient of increasing disturbance intensity. Fine root production, fine root turnover, and the associated carbon fluxes from the fine root system to the soil were estimated with three different approaches in five stands ranging from an old growth forest with negligible anthropogenic disturbance to a cacao agroforestry system with planted shade trees. Annual fine root production and mortality in three natural forest sites with increasing canopy openness decreased continuously with increasing forest disturbance, with a reduction of more than 45% between the undisturbed forest and the forest with large timber extraction. Cacao agroforestry stands had higher fine root production and mortality rates than forest with large timber extraction but less than undisturbed forest. The amount of carbon annually transferred to the soil carbon pool through fine root mortality was highest in the undisturbed forest and generally decreased with increasing forest use intensity. However, root-related C flux was also relatively high in the plantation with planted shading trees. In contrast, the relative importance of C transfer from root death in the total above- and below-ground C input to the soil increased with increasing forest use intensity and was even similar to the C input via leaf litter fall in the more intensively managed agroforest. We conclude that moderate to heavy disturbance in South-east Asian tropical moist forests has a profound impact on fine root turnover and the related carbon transfer to the soil.  相似文献