有关土地测绘质量问题和处理研究

文章就土地测绘的内涵解析作为切入点,浅要论述了土地测绘质量问题的影响因素,并就土地测绘质量问题影响因素的处理提出了一些浅薄的建议。以期促进我国土地测绘质量的提升。     

Carbon Depletion by Plowing and its Restoration by No‐Till Cropping Systems in Oxisols of Subtropical and Tropical Agro‐Ecoregions in Brazil

The continuous use of plowing for grain production has been the principal cause of soil degradation. This project was formulated on the hypothesis that the intensification of cropping systems by increasing biomass‐C input and its biodiversity under no‐till (NT) drives soil restoration of degraded agro‐ecosystem. The present study conducted at subtropical [Ponta Grossa (PG) site] and tropical regions [Lucas do Rio Verde, MT (LRV) site] in Brazil aimed to (i) assess the impact of the continuous plow‐based conventional tillage (CT) on soil organic carbon (SOC) stock vis‐à‐vis native vegetation (NV) as baseline; (ii) compare SOC balance among CT, NT cropping systems, and NV; and (iii) evaluate the redistribution of SOC stock in soil profile in relation to soil resilience. The continuous CT decreased the SOC stock by 0·58 and 0·67 Mg C ha⁻¹ y⁻¹ in the 0‐ to 20‐cm depth at the PG and LRV sites, respectively, and the rate of SOC sequestration was 0·59 for the PG site and ranged from 0·48 to 1·30 Mg C ha⁻¹ y⁻¹ for the LRV site. The fraction of C input by crop residues converted into SOC stock was ~14·2% at the PG site and ~20·5% at the LRV site. The SOC resilience index ranged from 0·29 to 0·79, and it increased with the increase in the C input among the NT systems and the SOC sequestration rates at the LRV site. These data support the hypothesis that NT cropping systems with high C input have a large potential to reverse the process of soil degradation and SOC decline. Copyright © 2013 John Wiley & Sons, Ltd.     

Changes in Physical Properties of Soils with Land Use Time in the Brazilian Savanna Environment

Soils from central Brazil have been intensively used over the last decades because of the rapid conversion of savannas ( Cerrado ) into corn/soybean fields. The objective of this work is to study modifications in the physical properties of soils in the Rio Verde watershed, as a function of the land use time for agriculture, determined from classification of Landsat satellite images between 1980 and 2010. Soil samples were collected at surface (0–20 cm) and subsurface (20–40 cm) horizons for the different classes of land use time (<10, 10–20, 20–30, and >30 years). The following physical properties were measured: bulk density (BD), air permeability (K_a), penetration resistance (PR), microporosity (MI), macroporosity (MA), and total porosity (TP). Results showed a strong expansion with time of agriculture that occupied 35·3% (1980), 37·4% (1990), 51·3% (2000), and 60·9% (2010) of the watershed area. When properties were compared with those from the reference areas (preserved soils under native vegetation), significant differences were observed for all the physical attributes of soils for a land use time higher than 20 years. Overall, BD and PR increased with land use time, and the opposite was verified for K_a, MA, and TP. Some physical properties presented values (e.g., 1·54 g cm⁻³ for BD and 0.06 cm³ cm⁻³ for MA) close to the critical ones reported to affect crop development, but they were not still impacting on local soybean yield. Copyright © 2013 John Wiley & Sons, Ltd.     

Impact of Land Use and Land Cover Changes on Organic Carbon Stocks in Mediterranean Soils (1956–2007)

During the last few decades, land use changes have largely affected the global warming process through emissions of CO₂. However, C sequestration in terrestrial ecosystems could contribute to the decrease of atmospheric CO₂ rates. Although Mediterranean areas show a high potential for C sequestration, only a few studies have been carried out in these systems. In this study, we propose a methodology to assess the impact of land use and land cover change dynamics on soil organic C stocks at different depths. Soil C sequestration rates are provided for different land cover changes and soil types in Andalusia (southern Spain). Our research is based on the analysis of detailed soil databases containing data from 1357 soil profiles, the Soil Map of Andalusia and the Land Use and Land Cover Map of Andalusia. Land use and land cover changes between 1956 and 2007 implied soil organic C losses in all soil groups, resulting in a total loss of 16·8 Tg (approximately 0·33 Tg y⁻¹). Afforestation increased soil organic C mostly in the topsoil, and forest contributed to sequestration of 8·62 Mg ha⁻¹ of soil organic C (25·4 per cent). Deforestation processes implied important C losses, particularly in Cambisols, Luvisols and Vertisols. The information generated in this study will be a useful basis for designing management strategies for stabilizing the increasing atmospheric CO₂ concentrations by preservation of C stocks and C sequestration. Copyright © 2012 John Wiley & Sons, Ltd.     

平原丘陵地区水土资源联合优化配置

通过对区域水资源和土地资源概况进行研究,利用大系统递阶优化思想,以供水对象相对缺水率最小和农业经济效益最大为目标,建立了区域水土资源联合优化配置模型,并以句容市为例,对平原丘陵地区的水资源在时间和区域上进行了合理安排、设计、组合和布局,对农业种植结构进行了调整。研究结果表明:水资源是土地资源发挥最大优势的基本条件,水资源利用合理与否,直接影响到土地资源的生产效率;而土地资源的利用程度也影响着水资源的变化,土地资源利用效率高,则为水资源的合理开发利用创造条件。     

呼伦贝尔地区不同土地利用下土壤蒸发野外试验研究

土壤蒸发是水文过程的关键环节之一,控制着水分由土壤环境向大气环境的扩散。通过在呼伦贝尔地区典型草地与林地设置相同口径不同深度微型蒸发仪(Micro-Lysimeter,简称ML)的对比,寻求适合林地草地使用的微型蒸发仪,并研究不同土地利用方式对土壤蒸发的影响,探讨环境因素对土壤蒸发结果的影响。结果表明:土壤蒸发量随ML长度的增加先增大后减小,相同直径长度不同ML的蒸发量在0.05水平下显著相关,测定林地的蒸发量小于草地蒸发量,不封底ML所测定结果比封底ML大,其结果更接近真实情况,测量呼伦贝尔地区土壤蒸发时,亦采用15cm的不封底ML,结果较好。     

长株潭城市群土地利用变化现状及策略分析

文章通过对长株潭城市群土地利用现状剖析,结合相关的理论提出相应的策略：以循环经济理念指导土地利用,优化土地利用结构与布局。     

基于PSR模型的兰州市土地生态安全时空差异评价

研究了兰州市2006~2013年土地生态安全的时空差异。主要依据PSR模型建立评价指标体系,运用熵权法与综合评价法对不同时期兰州市及各县区土地生态安全状况进行分析。结果表明:(1)兰州市土地生态安全由2006年的"恶劣"状态转变为2013年的"良好"状态;(2)土地生态压力指数从0.176下降为0.145,土地生态状态与土地生态响应指数分别从0.063、0.160提升到0.295、0.290;(3)区域内空间分布差异较为明显,土地生态状态改善与响应增强主要集中在土地生态压力过大的地方。据此可知,兰州市土地生态结构和功能基本完善,已步入良好阶段,但是各县区土地生态空间分布差异较大。     

抗旱保水剂在岗坡旱地甘薯上的应用试验

为提高冀南地区岗坡旱地农作物产量,应用抗旱保水剂在甘薯上进行了试验。结果表明,施用抗旱保水剂可提高甘薯幼苗成活率,促进甘薯生长,增产增收,以45kg/hm2用量效果最好。     

北方农牧交错带土地利用结构的线性规划——以定西县为例

探讨了用线性规划方法优化土地利用结构,并以北方农牧交错带定西县土地利用结构的经济效益作为目标函数,以人口和自然条件作为约束条件,进行优化分析,规划结果为定西县土地利用结构由2005年的农、林、草面积比例54:10:36调整为30:13:57.