黄河三角洲盐碱地不同利用方式土壤理化性质

为了缓解土壤盐碱性,保证土壤可持续利用,研究了黄河三角洲典型土地利用类型撂荒地、棉田、苜蓿地和梨园土壤理化性质.结果表明:棉田土壤容重较高,而孔隙度和毛管孔隙度低,由于棉田灌水压盐措施,抬高了地下水位,土壤返盐严重.苜蓿地由于管理粗放,对土壤扰动少,容重较低,孔隙度和毛管孔隙度较高,盐碱度较低;每年对苜蓿的采收显著降低了苜蓿地土壤有机质和养分含量,而豆科固氮菌的存在,使表层速效氮含量较高.梨园位于黄河三角洲土壤质地较好的区域,且有机肥料施用一定程度上缓解了土壤板结,盐碱度较低.撂荒地表层土壤理化指标均显著优于棉田,在退化土壤恢复中具有较好的效果.     

不同土地利用方式对黄河三角洲盐碱地土壤理化性质的影响

采用野外调查取样和室内分析相结合的方法,分析3种不同土地利用方式对黄河三角洲河口区盐碱地土壤理化性质的影响。结果表明:1)刺槐林地土壤表层0～10 cm有机质和全氮质量分数均最高,分别为17.30和1.04g/kg,0～20 cm平均土壤密度(1.33 g/cm3)和0～100 cm平均土壤电导率(290.25μs/cm)均小于柽柳林地和棉花地,0～20 cm平均土壤孔隙度(51.91%)和黏粒质量含量(3.99%)均大于柽柳林地和棉花地;2)柽柳林地0～100cm平均土壤pH值为6.77,极显著低于刺槐林地和棉花地(P<0.01),平均土壤速效钾质量分数最高(104.47 mg/kg),极显著高于棉花地(P<0.01),而与刺槐林地差异不显著,0～100 cm平均土壤速效磷质量分数为棉花地>柽柳林地>刺槐林地;3)人工栽植的刺槐林地土壤理化性状优于天然更新的柽柳林地和人工耕作的棉花地。研究结果可为黄河三角洲河口区盐碱地土地合理利用和改良提供参考。     

基于土地利用和覆被变化的黄河三角洲土壤质量预警研究

该文通过1987和2002年黄河三角洲土地利用和覆被变化与土壤肥力变化的对比分析，探讨土地利用和覆被变化对土壤肥力的影响。研究结果表明：土地利用和覆被变化对土壤肥力变化有直接影响，耕地转为林草地、建设用地、盐荒地和沙地，土壤肥力均有下降趋势；林草地转为滩涂的土壤肥力明显下降，转为盐荒地的略有下降；沙地转为耕地的土壤肥力明显提高，转为林草地有下降趋势，转为盐荒地的略有提高或不变；盐荒地转为耕地的土壤肥力有较大的提高，转为林草地的保持不变或稍有下降，转为沙地的稍有提高，转为建设用地的略微下降；滩涂转为盐荒地的土壤肥力保持不变或略微下降，转为林草地的稍有提高。     

Impacts of land use and cropland management on soil organic matter and greenhouse gas emissions in the Brazilian Cerrado

The Brazilian Cerrado is a large and expanding agricultural frontier, representing a hotspot of land-use change (LUC) from natural vegetation to farmland. It is known that this type of LUC impacts soil organic matter (SOM) dynamics, particularly labile carbon (C) pools (living and non-living), decreasing soil health and agricultural sustainability, as well as increasing soil greenhouse gas (GHG) emissions, and accelerating global climate change. In this study, we quantified the changes in the quantity and quality of SOM and GHG fluxes due to changes in land use and cropland management in the Brazilian Cerrado. The land uses studied were native vegetation (NV), pasture (PA) and four croplands, including the following management types: conventional tillage with a single soybean crop (CT), and three no-tillage systems with two crops cultivated in the same year (i.e., soybean/sorghum (NT_SSo), soybean/millet (NT_SMi) and maize/sorghum (NT_MSo)). Soil and gases were sampled in the rainy season (November, December and January) and dry season (May, July and September). The highest soil C and nitrogen (N) stocks (6.7 kg C m⁻² and 0.5 kg N m⁻², 0–0.3-m layer) were found under NV. LUC reduced C stocks by 25% in the CT and by 10% in the PA and NT. Soil N stocks were 30% lower in the PA and NT_MSo and 15% lower in the croplands with soybean compared to NV. δ¹³C values clearly distinguished between the C-origin from NV (−25‰) and that from other land uses (−16‰). Soil (0–0.1 m) under NV also presented higher labile-C (625 g C m⁻²), microbial-C (70 g C m⁻²) and microbial-N (5.5 g N m⁻²), whereas other land uses presented values three times lower. GHG emissions (expressed as C-equivalent) were highest in the NV (1.2 kg m⁻² year⁻¹), PA (1.3 kg m⁻² year⁻¹) and NT_MSo (0.9 kg m⁻² year⁻¹) and were positively related to the higher SOM turnover in these systems. Our results suggest that in order to maintain SOM, it is necessary to adopt “best” management practices, that provide large plant residue inputs (above- and belowground). This can be seen as a pathway to achieving high food production with low GHG emissions.     

土地整理对农田土壤碳含量的影响

土地整理对土壤的强扰动会影响土壤的碳循环平衡,为了研究土地整理对农田土壤碳含量的影响,通过间接采样和随机采样方法,采集了江苏3个土地整理区土地整理前后土样进行有机质测定,初步分析了不同土地整理区土地整理后的土壤碳含量变化及其变化差异原因。主要结论有：1）通过土地整理,3个土地整理区土壤碳含量都有得到提高。其中,苏南丹阳土地整理区碳质量分数提高了26.05%,碳密度提高23.87%,提高幅度最大,碳密度变化方向与碳含量变化具有一致性,但提高幅度低于碳含量。这与各整理区原有土质、土地整理工程施工方式、施工时间等因素密切相关。2）水田碳质量分数显著高于旱地碳质量分数,但是经过土地整理旱地碳含量提高幅度大于水田,水田在整理前后碳含量变化幅度不大。3）在土地整理项目实施前应制定适宜的土地整理规划,实施有利于土壤固碳的土地整理工程。     

不同土壤类型和农业用地方式对土壤微生物量碳的影响

通过野外调查与室内分析,研究了山东桓台县3种土壤类型(潮土、褐土和砂姜黑土)与农业用地方式(林地、菜地和粮田)对土壤表层(0—10.cm)微生物量碳的影响。结果表明,不同农业用地方式对微生物量碳的影响较大,3种利用方式的微生物量碳含量差异显著,依次为:粮田>菜地>林地;土壤类型不同,土壤微生物量碳含量也不相同。任何一种土壤,菜地的N、P、K含量都高于粮田和林地;有机质含量粮田>菜地>林地;pH值林地>粮田>菜地。全N、有机质与土壤微生物量碳呈极显著正相关,有效P与微生物量碳呈弱负相关,速效K、pH值和微生物量碳不相关。不同用地方式下土壤养分与微生物量碳的相关程度不同。秸秆还田和施用有机肥有利于提高土壤中微生物量碳水平,施用化肥在一定程度上能够增加微生物量碳。     

艾比湖绿洲农业区土地利用动态与盐碱化影响的遥感应用研究

采用1972～2001年的4期MSS和TM图像为数据源,通过人工解译方法获得新疆艾比湖地区土地利用数据,并使用土地利用转移矩阵和土地利用变化指数等方法分析近30a该地区土地利用动态情况。在此基础上,应用基于光谱分析的光谱角度填图(SAM)分类方法从2004年ASTER和SPOT图像上提取土地盐碱化现状信息,与人工解译的土地利用数据进行空间分析,对农业区土地利用受盐碱化影响的程度进行评估,并对盐碱化因素限制下的农业发展提出建议。研究结果表明,近30a来该地区耕地面积持续增加,新开垦耕地主要来源于未利用地的开发。新开垦耕地明显地受到盐碱化的影响,农业生产将受到一定威胁。     

A soil carbon and land use database for the United Kingdom

Abstract. The compilation of a database of soil carbon and land use is described, from which models of soil carbon dioxide emissions across the United Kingdom (UK) can be run. The database gives soil organic carbon, sand, silt and clay contents and bulk densities weighted to reference layers from 0 to 30 cm and from 30 to 100 cm depths. The data are interpolated from information on soil types and land use on a 1 km grid across the UK and are used to estimate soil carbon stocks. For 1990, the baseline year for the Kyoto Protocol on carbon emissions, the estimate is 4562 Tg soil organic carbon in the top 1 m of soil across the UK, with an average density of 18 kg m⁻². The data can be reported by layer (e.g. 54% in topsoils) and country (e.g. 48% in Scotland) as well as by soil and land type.     

The sensitivity of water extractable soil organic carbon fractions to land use in three soil types

Soil organic carbon (SOC) has a high impact on the sustainability of ecosystems, global environmental processes, soil quality and agriculture. Long-term tillage usually leads to SOC depletion. The purpose of this study was to determine the impact of different land uses on water extractable organic carbon (WEOC) fractions and to evaluate the interaction between the WEOC fractions and other soil properties. Using an extraction procedure at 20°C and 80°C, two fractions were obtained: a cold water extractable organic carbon (CWEOC) and a hot water extractable organic carbon (HWEOC). The results suggest that there is a significant impact from different land uses on WEOC. A lower relative contribution of WEOC in SOC and a lower concentration of labile WEOC fractions are contained in arable soil compared to forestlands. Chernozem soil was characterized by a lower relative contribution of WEOC to the SOC and thus higher SOC stability in contrast to Solonetz and Vertisol soils. Both CWEOC and HWEOC are highly associated with SOC in the silt and clay fraction (<53 µm) and were slightly associated with SOC in the macroaggregate classes. The WEOC fractions were highly and positively correlated with the SOC and mean weight diameter.     

Assessing scale effects on modelled soil organic carbon contents as a result of land use change in Belgium

This paper explores the influence of spatial scale on modelled projections of soil organic carbon (SOC) content. The effect of land use change (LUC) on future SOC stocks was estimated using the Rothamsted Carbon model for a small area of southern Belgium. The study assumed no management change and used a single climate change scenario. Three model experiments were used to identify how data scale affects predicted SOC stocks: (i) using European LUC datasets at a resolution of 10′ and assuming equal distribution of change within the study area, (ii) using more accurate regional data aggregated to the 10’ resolution, and (iii) using the regional data at a spatial resolution of 250 m. The results show that using coarse resolution (10′) data is inappropriate when modelling SOC changes in the study area as only the methods using precise data predict a change in SOC stocks similar to those reported in the literature. This is largely because of differences in model parameterisation. However, precisely locating LUC does not significantly affect the results. The model, using either pan‐European or region‐specific precise data predicts an average SOC increase of 1 t C ha^?1 (1990–2050), mainly resulting from afforestation of 13% of agricultural land.     

广东省典型土壤类型和土地利用方式对土壤酶活性的影响

通过野外调查与室内分析,研究了广东省韶关红壤、广州赤红壤、雷州砖红壤3个典型地带性土壤分布区4种不同土地利用方式(包括林地、果园、草地和农田)对表层(0~20 cm)土壤几种主要酶活性(过氧化氢酶、纤维素酶、蔗糖酶、脲酶、蛋白酶活性)的影响。结果表明,不同土壤类型和不同土地利用方式对土壤酶活性均有一定影响,其中土地利用方式影响更为明显。土壤酶活性多表现为果园和林地较高,农田和草地较低;而土壤过氧化氢酶对土地利用方式和土壤类型的响应均较其它几种酶弱。典范相关分析结果表明,全磷、速效磷、速效氮含量是土壤养分因子中影响土壤酶活性的最重要因素,5种酶中纤维素酶和蛋白酶活性与土壤养分因子关系最大,而土壤酶活性之间也存在着一定的共性关系。     

黄河三角洲不同土地利用类型土壤微观结构特征

黄河三角洲不同土地利用类型盐碱土微观结构的研究,对认识该地区盐碱土的工程性质和对滨海盐碱地治理具有重要意义。该研究结合粒度分析(particle size distribution,PSD)、X射线衍射(X-ray diffraction,XRD)、压汞(mercury intrusion porosimetry,MIP)和扫描电镜(scanning electron microscopy,SEM)方法,对3种不同土地利用类型盐碱土的微观结构进行定量分析,旨在揭示其微观特性,为黄河三角洲盐碱地治理提供微观理论依据。结果表明:不同土地利用类型下的土壤黏粒含量表现大小依次为农田、滩地、草地,而土壤孔隙度大小依次为草地、滩地、农田;农田、草地与滩地盐碱土矿物成分中,石英、方解石和钠长石等原生矿物占绝对优势,仅含少量黏土矿物,且农田黏土矿物含量远大于草地与滩地;草地与滩地盐碱土孔隙特征类似,两者在0.1≤孔隙直径<10μm范围内小孔隙与微孔隙占有绝对优势,而农田盐碱土以孔隙直径在<2μm范围内的微孔隙与超微孔隙为主。农田盐碱土由致密片状、扁平状结构与微裂隙构成,骨架颗粒间由黏土矿物胶结;草地盐碱土由紧密镶嵌的块状颗粒和架空孔隙构成,骨架颗粒间无胶结;滩地盐碱土由紧密堆积的粒状颗粒和粒间孔隙构成,骨架颗粒间无胶结。研究成果可提高对黄河三角洲不同土地利用类型盐碱土微观结构的认识,为滨海盐碱地的治理、利用和开发提供了微观尺度上的依据。     

不同利用方式对棕壤有机碳垂直分布的影响

采用野外采样和室内分析的方法研究了林地、园地、耕地3种利用方式对典型棕壤总有机碳(TOC)、颗粒有机碳(POC)及重组有机碳(HFOC)在0～20 cm、20～40 cm、40～60 cm 3层次中垂直分布的影响。结果表明,与林地相比,园地和耕地各层次的TOC含量和储量均显著下降;其分布份额和分布比则为园地中、下层略向上层转移,耕地则明显向中、下层转移。3种利用方式下POC的相对数量均随土层加深而递减,林地开垦为园地和耕地后,POC的相对数量仅在园地上、中层显著降低,分别减少6.67和1.70个百分点,而耕地则各层次均显著降低,其相对数量分别减少13.65、5.43和3.03个百分点;HFOC的相对数量随干预强度和土层深度增加而增大,耕地和园地比林地分别高出:上层5.77和4.00个百分点、中层10.44和6.40个百分点、下层7.35和3.92个百分点,且差异均显著。因此,将林地棕壤开垦为园地或耕地后应注重有机物料的投入,以减缓因开垦对有机碳所造成的损失和不尽合理的分布状况。     

珠江三角洲土地利用/覆盖变化对地表温度的影响

Remote sensing and geographic information systems （GIS） technologies were used to detect land use/cover changes （LUCC） and to assess their impacts on land surface temperature （LST） in the Zhujiang Delta. Multi-temporal Landsat TM and Landsat ETM＋ data were employed to identify patterns of LUCC as well as to quantify urban expansion and the associated decrease of vegetation cover. The thermal infrared bands of the data were used to retrieve LST, The results revealed a strong and uneven urban growth, which caused LST to raise 4.56℃ in the newly urbanized part of the study area. Overall, remote sensing and GIS technologies were effective approaches for monitoring and analyzing urban growth patterns and evaluating their impacts on LST.     

Influence of former lynchets on soil cover structure and soil organic carbon storage in agricultural land,Central Czechia

Lynchets represent a traditional landscape element in agricultural landscapes having multiple functions in soil material redistribution, water retention, biodiversity and landscape character. They act as a barrier to translocated soil matter, and they can store a significant amount of soil material and soil organic carbon. Lynchets developed in many regions during formation of agriculture landscape as field boundaries or path networks. Further management led to unleveling of the fields and development of lynchets. During the 20th century, a large number of lynchets disappeared in Central and Western Europe due to land consolidation, intensification and industrialization of agriculture. This study was performed at a large agricultural study plot with dissected relief (Central Czechia) with the aim of assessing the influence of former but now completely levelled lynchets on actual soil stratigraphy, depth, soil organic carbon stocks and structure of soil units. The soil profiles in 20‐m‐long transects perpendicular to former lynchets were analysed, and statistical relationships between the positions above, in and below the former lynchets were assessed. The results showed high variability of studied soil characteristics in the areas of former lynchets. Statistically significant greater A horizon thickness (50–100 cm) and SOC stock (12.7 kg/m²) were observed in the location of a former lynchet, where colluvial soils were identified. Other areas of accumulation were identified below a lynchet, at the former break‐in‐slope. The strip above a lynchet was identified as a sediment delivery area, having a partly truncated soil profile. SOC concentration and SOC stock in A horizon did not differ significantly in the positions in, above or below a lynchet.     

Land Use and Soil Organic Carbon in China’s Village Landscapes

Village landscapes, which integrate small-scale agriculture with housing, forestry, and a host of other land use practices, cover more than 2 million square kilometers across China. Village lands tend to be managed at very fine spatial scales (≤ 30 m), with managers both adapting their practices to existing variation in soils and terrain (e.g., fertile plains vs. infertile slopes) and also altering soil fertility and even terrain by terracing, irrigation, fertilizing, and other land use practices. Relationships between fine-scale land management patterns and soil organic carbon (SOC) in the top 30 cm of village soils were studied by sampling soils within fine-scale landscape features using a regionally weighted landscape sampling design across five environmentally distinct sites in China. SOC stocks across China’s village regions (5 Pg C in the top 30 cm of 2 × 10 6 km 2 ) represent roughly 4% of the total SOC stocks in global croplands. Although macroclimate varied from temperate to tropical in this study, SOC density did not vary significantly with climate, though it was negatively correlated with regional mean elevation. The highest SOC densities within landscapes were found in agricultural lands, especially paddy, the lowest SOC densities were found in nonproductive lands, and forest lands tended toward moderate SOC densities. Due to the high SOC densities of agricultural lands and their predominance in village landscapes, most village SOC was found in agricultural land, except in the tropical hilly region, where forestry accounted for about 45% of the SOC stocks. A surprisingly large portion of village SOC was associated with built structures and with the disturbed lands surrounding these structures, ranging from 18% in the North China Plain to about 9% in the tropical hilly region. These results confirmed that local land use practices, combined with local and regional variation in terrain, were associated with most of the SOC variation within and across China’s village landscapes and may be an important cause of regional variation in SOC.     

Soil particulate organic carbon under different land use and management

Abstract. Changes in particulate organic carbon (POC) relative to total organic carbon (TOC) were measured in soils from five agronomic trial sites in New South Wales, Australia. These sites covered a wide range of different land use and management practices. POC made up 42–74% of TOC and tended to be greater under pasture and more conservative management than traditional cropping regimes. It was the form of organic carbon preferentially lost when soils under long-term pasture were brought under cultivation. It was also the dominant form of organic carbon accumulating under more conservative management practices (direct drilling, stubble retained and organic farming). Across all sites, changes in POC accounted for 81.2% (range 69–94%) of the changes in total organic carbon caused by differences in land use and management. Significant differences were found between pasture and cropped soils in the carbon content in the <53 μm fraction, particularly for hardsetting soils. However, even with these, POC was a more sensitive indicator of change caused by land use and management practices than TOC. The current method for measuring POC involves dispersion using sodium hexametaphosphate. The dispersing agent was found to extract 4–19 % of the TOC, leading to a significant under-estimation of POC.     

伊金霍洛旗不同土地利用方式下的土壤养分特征

为分析内蒙古鄂尔多斯市伊金霍洛旗在4类土地利用方式(灌木林地、采矿用地、天然牧草地和农地)下,土壤养分质量分数的差异性,运用野外采样和室内化验、分析相结合的方法,测定4种土地类型在0～30 cm土层的土壤有机质和全量氮磷钾质量分数及pH值.结果表明:1)4类土地在0～ 30 cm土层的土壤有机质和全氮质量分数存在显著差异,土壤全磷量和全钾量差异不显著(P＜0.05),土壤有机质质量分数依次为农地＞天然牧草地＞灌木林地＞采矿用地,土壤全量氮磷钾最大值分别为天然牧草地、天然牧草地和灌木林地,最小值分别为采矿用地、灌木林地和天然牧草地;2)在垂直剖面上,采矿用地和天然牧草地的有机质质量分数随着土层深度的增加逐渐减小,农地和灌木林地的有机质质量分数最大值出现在20～30 cm深度的土层,4类土地的土壤全氮量和全磷量均有随土层深度的增加而下降的趋势,全钾量随土层深度的变化不明显.4类土地的土壤全氮和全钾质量分数整体而言较为理想,全磷和有机质质量分数欠缺.农地全磷质量分数基本能满足主要作物的生长需求,有机质和全氮质量分数不能满足主要作物的生长需求.本研究可为内蒙古中部工矿开采区土地合理利用以及退化的生态环境恢复等提供科学依据.     

黄土高原小流域土壤有机碳空间变异性研究

Soil organic carbon (SOC) has great impacts on global warming, land degradation and food security. Classic statistical and geostatistical methods were used to characterize and compare the spatial heterogeneity of SOC and related factors, such as topography, soil type and land use, in the Liudaogou watershed on the Loess Plateau of North China. SOC concentrations followed a log-normal distribution with an arithmetic and geometric means of 23.4 and 21.3 g kg^-1, respectively, were moderately variable (CV = 75.9%), and demonstrated a moderate spatial dependence according to the nugget ratio (34.7%). The experimental variogram of SOC was best-fitted by a spherical model, after the spatial outliers had been detected and subsequently eliminated. Lower SOC concentrations were associated with higher elevations. Warp soils and farmland had the highest SOC concentrations, while aeolian sand soil and shrublands had the lowest SOC values. The geostatistical characteristics of SOC for the different soil and land use types were different. These patterns were closely related to the spatial structure of topography, and soil and land use types.     

黄河三角洲自然保护区土地利用格局空间优化模拟

空间优化模型能够实现多管理目标下的土地利用格局空间优化,为管理者制定保护政策提供参考。该文以黄河三角洲自然保护区为研究区域,基于保护区的多目标管理需求,设计了3种用于协调丹顶鹤生境保护和社区可持续发展的情景模式,并采用土地利用空间优化(land use pattern optimization,LUPO)模型,模拟实现了不同情景模式下的保护区土地利用格局空间优化配置。模拟结果表明:情景A通过将光滩和芦苇滩等转为丹顶鹤喜好的翅碱蓬滩涂和柽柳-翅碱蓬滩涂,实现使丹顶鹤适宜生境面积增加30%的生态效益目标,但年经济收益增幅仅为11%;情景B通过将农田、芦苇滩和光滩等转为年经济效益更高的虾池,使区域年经济效益增长54%,但丹顶鹤适宜生境面积变化较小,生境更为破碎化;情景C通过将光滩等转为翅碱蓬滩涂,将农田等转为虾池,分别使丹顶鹤适宜生境面积增加24%和区域年经济效益增长41.3%,是一种双赢方案。研究结果表明,该模型可用于保护区土地利用格局空间优化,协调物种保护和经济发展之间的平衡关系,但需对模型结构和参数进一步优化设计。