基于检索1950-2016年发表在中国知网、Google Scholar、Web of Science等数据库的文章,筛选出关于我国退耕还草工程与土壤有机碳的文献123篇(126个研究地点)。基于筛选文献,提取了农田和恢复草地的土壤有机碳含量、土壤有效养分含量、...基于检索1950-2016年发表在中国知网、Google Scholar、Web of Science等数据库的文章,筛选出关于我国退耕还草工程与土壤有机碳的文献123篇(126个研究地点)。基于筛选文献,提取了农田和恢复草地的土壤有机碳含量、土壤有效养分含量、恢复时间和气候等数据735条,旨在探究我国退耕还草工程对土壤有机碳含量的影响及其主导因素。结果表明:1)农田恢复为草地后,土壤有机碳含量呈先下降后上升趋势(时间拐点约为第6年),整体上退耕还草工程使土壤有机碳含量提高了19.8%。2)土壤有机碳的正响应随土壤深度增加而减弱,且深度超过1 m时其正响应不明显。3)土壤有效氮是影响土壤有机碳恢复的主要因素,而土壤有效磷和植物功能群对其影响不大。4)沿着增加的水分梯度,土壤有机碳的恢复效果由负变正,转变阈值为25.15 (干旱指数)。总体而言,我国退耕还草工程对土壤有机碳含量的影响为正效应,此效应受环境梯度和恢复时间的共同影响。本研究能够为我国土地利用变化背景下土壤碳库管理的相关决策提供科学依据。展开更多
Analyses of desertified land and land use change in Naiman County of Inner-Mongolia showed that there was a fluctuated in-crease of rain-fed cropland in the period from 1951 to 1960, then decreased until the middle of...Analyses of desertified land and land use change in Naiman County of Inner-Mongolia showed that there was a fluctuated in-crease of rain-fed cropland in the period from 1951 to 1960, then decreased until the middle of the 1990＇s, then increased again, while irrigated cropland consistently increased. The woodland and build-up land consistently increased while grassland area de-creased. The area of water body increased from 1975 to 1995 and then decreased while river beach decreased. Wetland change fluctuated with a maximum of 303.53km2 in 1995 and a minimum of 62.08 km2 in 2002. Invasion of cropland into river beach does not only change land coverage on the beach, but also the hydrological process of the river systems and deeply influence wa-ter availability. The correlation between cropland and underground water table is negative and significant. Increase of irrigated cropland is the primary cause of water availability reduction. Water table reduction is negatively correlated to cropland. The total desertified land has decreased since 1975. A rapid increase occurred before 1959, but it is difficult to assess the change of deserti-fication due to lack of data from 1959 to 1975. Changes of different types of desertified lands were different. There is no signifi-cant correlation between land use and different types of desertified land, but there is a significant negative correlation between woodland and total desertified land. The correlation between grassland and total desertified land is positive and significant. There is a significant correlation between different land cover and key factors such as water body and annual precipitation, river beach and runoff, area of shifting dune and annual precipitation, and cropland and underground water table. Desertification reversion in Naiman County is fragile and will be even much more fragile due to population growth, rapid land use and climate change. This will lead to continued invasion of irrigated cropland into more fragile ecosystems and reduction of water availability.展开更多
Background： Site-vegetation relations of Vachellia erioloba, Faidherbia albido, Euclea pseudebenus and Tamarix usneoides in two contrasting locations in the Namib Desert （Namibia） were evaluated with the goal to re...Background： Site-vegetation relations of Vachellia erioloba, Faidherbia albido, Euclea pseudebenus and Tamarix usneoides in two contrasting locations in the Namib Desert （Namibia） were evaluated with the goal to relate soil water availability to the occurrence of trees under hyper-arid conditions, Methods： Plant water potentials were measured using a pressure chamber in the field. Pre-dawn water potentials were assessed to reflect the soil water potential of the rhizosphere. Midday water potentials were measured to assess the strongest negative water potential applied by the sample trees. Results： Pre-dawn water potentials and midday water potentials indicated access to soil water in the rhizosphere and by this, provide an explanation for an occurrence of V. erioloba within the extreme environmental conditions of sand dunes in the Namib Desert. Diurnal ranges seem to reflect more and less suitable stands, in terms of soil water availability, within the sampling sites. While the impact of the ephemeral Kuiseb river on soil water availability was assessed through the four species＇ plant-internal water relations, comparable pre-dawn water potentials of V. erioioba at both sites indicate soil water availability also in the dunes of Namibrand. The extreme midday water potentials of the dune plants possibly show the upper limit of tolerance for V. eriolobo. Conclusions： The preliminary data provide an explanation of the occurrence and distribution of the investigated species in beds of ephemeral rivers and on dunes under the hyper-arid climatic conditions of the Namib Desert and qualify suitability within the assessed sites. Understanding the plant-physiological processes and assessing the plant-internal water potential provides a valuable tool to evaluate soil water availability within the rhizosphere and to describe an adaptation potential of investigated species. The comparability of pre-dawn water potentials at both sites indicates unexpected soil water availability within lower parts of the dunes of Namibrand. Further research needs are derived concerning the origin and distribution of such soil water. These species in these specific tree-environments are understudied and little published, thus the results support an improved understanding of the ecology in arid environments.展开更多
利用观测气象数据集(CN05.1)、地表水文数据集(VIC-CN05.1)以及大气再分析数据(JRA55)分析了我国西北地区1961-2016年暖季(5-9月)陆地水分收支的长期和年代际变化特征。通过对陆地水分收支(Land Water Availability,LWA)时间序列作Mann-...利用观测气象数据集(CN05.1)、地表水文数据集(VIC-CN05.1)以及大气再分析数据(JRA55)分析了我国西北地区1961-2016年暖季(5-9月)陆地水分收支的长期和年代际变化特征。通过对陆地水分收支(Land Water Availability,LWA)时间序列作Mann-Kendall突变检验,将1961-2016年划分为3个时段进行进一步分析(P1:1961-1978年;P2:1979-2008年;P3:2009-2016年)。主要结论如下:在1961-2016年间西北地区LWA呈上升趋势,区域平均的LWA时间序列具有明显的年代际特征。三个时段的LWA距平百分率分别为-5.45%、-0.46%和13.99%,总体表现为“减少-不变-增加”的特征,尤其是近些年地表水资源增加明显。三个时段的LWA距平百分率空间分布差异显著,尤其在新疆中部、甘肃东部和陕西。西北地区总体上水汽通量输送和垂直速度与降水年代际变化特征基本一致,且区域特征明显。西北地区蒸发受降水、向下长波辐射通量和风速变化影响显著。展开更多
露天矿开采导致大面积的地貌改变和植被破坏,进行土地复垦是重建原有生态系统的有效手段。为改善锡林浩特矿区生态脆弱、且矿区表土稀缺的现状,利用上覆岩层进行表土替代材料的开发,上覆岩层土壤的持水能力是选择表土替代材料的重要指标...露天矿开采导致大面积的地貌改变和植被破坏,进行土地复垦是重建原有生态系统的有效手段。为改善锡林浩特矿区生态脆弱、且矿区表土稀缺的现状,利用上覆岩层进行表土替代材料的开发,上覆岩层土壤的持水能力是选择表土替代材料的重要指标,对于指导排土场复垦具有重要意义。基于此选取了AP(Arya and Paris模型)、MV(Mohammadi and Vanclooster模型)和MVVG(MV model with the van Genuchten模型) 3种模型对锡林浩特矿区上覆岩层(L1-L5,共5层)土壤水分特征曲线与土壤有效含水量的预测精度。结果显示:MVVG对于土壤水分特征曲线(R^2=0.940)与有效含水量(R^2=0.7409)的预测精度均较好,AP对于土壤水分特征曲线的预测结果最好(R^2=0.950),且对于剖面有效含水量的预测趋势与实测值一致,但是有效含水量的预测值与实测值R^2较低(R^2=0.491),MV预测结果最差。AP模型对壤质沙土、砂之壤土和粉砂壤土的水分特征曲线预测效果好于MV和MVVG,但是各模型对沙土的预测预测效果均较差。除L5层,其余4层随着土壤层次深度的增加,其田间持水量、凋萎系数和有效水含量均呈减少趋势。L2-L4的有效水含量均低于L1(18%),且L4(8%)<L3(11%)<L2(15%)。研究结果显示AP和MVVG模型可以准确地预测研究区土壤水分特征曲线和水分常数,适合用于锡林浩特矿区上覆岩层土壤持水能力的预测。同时结果表明,L5层的有效含水量最大(20%),且土层较厚,具有在土地复垦过程中作为表土替代材料的潜力,而L2-L4可以考虑作为中和L5质地过黏的材料,使其土质更加接近腐殖层土壤(L1)。展开更多
The aim of this paper is to analyse the possible impacts of proposed biofuel production at Hoedspruit in the Olifants River Catchment. These impacts are looked at in terms of availability of water and subsequent conse...The aim of this paper is to analyse the possible impacts of proposed biofuel production at Hoedspruit in the Olifants River Catchment. These impacts are looked at in terms of availability of water and subsequent consequences on downstream users, especially the Kruger National Park that is mandated to conserve and protect biodiversity in all facets and fluxes in its area of jurisdiction. Based upon a review of experiences with biofuel production and impacts around the world, water availability for sugar cane production to support proposed biofuel production was found to be a problem in the region that has an average rainfall of only 450 mmper annum. The Olifants River system already has a deficit of about 200 million m3/a;hence the sustainability of the sugar cane based biofuel industry in the proposed area is questioned in this review. It is advised that alternative plants for the production of biofuel that may not consume large quantities of water be examined.展开更多
基金funded by the research projects-2009CB421303 and KZCX2-YW-431
文摘Analyses of desertified land and land use change in Naiman County of Inner-Mongolia showed that there was a fluctuated in-crease of rain-fed cropland in the period from 1951 to 1960, then decreased until the middle of the 1990＇s, then increased again, while irrigated cropland consistently increased. The woodland and build-up land consistently increased while grassland area de-creased. The area of water body increased from 1975 to 1995 and then decreased while river beach decreased. Wetland change fluctuated with a maximum of 303.53km2 in 1995 and a minimum of 62.08 km2 in 2002. Invasion of cropland into river beach does not only change land coverage on the beach, but also the hydrological process of the river systems and deeply influence wa-ter availability. The correlation between cropland and underground water table is negative and significant. Increase of irrigated cropland is the primary cause of water availability reduction. Water table reduction is negatively correlated to cropland. The total desertified land has decreased since 1975. A rapid increase occurred before 1959, but it is difficult to assess the change of deserti-fication due to lack of data from 1959 to 1975. Changes of different types of desertified lands were different. There is no signifi-cant correlation between land use and different types of desertified land, but there is a significant negative correlation between woodland and total desertified land. The correlation between grassland and total desertified land is positive and significant. There is a significant correlation between different land cover and key factors such as water body and annual precipitation, river beach and runoff, area of shifting dune and annual precipitation, and cropland and underground water table. Desertification reversion in Naiman County is fragile and will be even much more fragile due to population growth, rapid land use and climate change. This will lead to continued invasion of irrigated cropland into more fragile ecosystems and reduction of water availability.
基金Gobabeb Research and Training Centre for support and input provided
文摘Background： Site-vegetation relations of Vachellia erioloba, Faidherbia albido, Euclea pseudebenus and Tamarix usneoides in two contrasting locations in the Namib Desert （Namibia） were evaluated with the goal to relate soil water availability to the occurrence of trees under hyper-arid conditions, Methods： Plant water potentials were measured using a pressure chamber in the field. Pre-dawn water potentials were assessed to reflect the soil water potential of the rhizosphere. Midday water potentials were measured to assess the strongest negative water potential applied by the sample trees. Results： Pre-dawn water potentials and midday water potentials indicated access to soil water in the rhizosphere and by this, provide an explanation for an occurrence of V. erioloba within the extreme environmental conditions of sand dunes in the Namib Desert. Diurnal ranges seem to reflect more and less suitable stands, in terms of soil water availability, within the sampling sites. While the impact of the ephemeral Kuiseb river on soil water availability was assessed through the four species＇ plant-internal water relations, comparable pre-dawn water potentials of V. erioioba at both sites indicate soil water availability also in the dunes of Namibrand. The extreme midday water potentials of the dune plants possibly show the upper limit of tolerance for V. eriolobo. Conclusions： The preliminary data provide an explanation of the occurrence and distribution of the investigated species in beds of ephemeral rivers and on dunes under the hyper-arid climatic conditions of the Namib Desert and qualify suitability within the assessed sites. Understanding the plant-physiological processes and assessing the plant-internal water potential provides a valuable tool to evaluate soil water availability within the rhizosphere and to describe an adaptation potential of investigated species. The comparability of pre-dawn water potentials at both sites indicates unexpected soil water availability within lower parts of the dunes of Namibrand. Further research needs are derived concerning the origin and distribution of such soil water. These species in these specific tree-environments are understudied and little published, thus the results support an improved understanding of the ecology in arid environments.
文摘利用观测气象数据集(CN05.1)、地表水文数据集(VIC-CN05.1)以及大气再分析数据(JRA55)分析了我国西北地区1961-2016年暖季(5-9月)陆地水分收支的长期和年代际变化特征。通过对陆地水分收支(Land Water Availability,LWA)时间序列作Mann-Kendall突变检验,将1961-2016年划分为3个时段进行进一步分析(P1:1961-1978年;P2:1979-2008年;P3:2009-2016年)。主要结论如下:在1961-2016年间西北地区LWA呈上升趋势,区域平均的LWA时间序列具有明显的年代际特征。三个时段的LWA距平百分率分别为-5.45%、-0.46%和13.99%,总体表现为“减少-不变-增加”的特征,尤其是近些年地表水资源增加明显。三个时段的LWA距平百分率空间分布差异显著,尤其在新疆中部、甘肃东部和陕西。西北地区总体上水汽通量输送和垂直速度与降水年代际变化特征基本一致,且区域特征明显。西北地区蒸发受降水、向下长波辐射通量和风速变化影响显著。
文摘露天矿开采导致大面积的地貌改变和植被破坏,进行土地复垦是重建原有生态系统的有效手段。为改善锡林浩特矿区生态脆弱、且矿区表土稀缺的现状,利用上覆岩层进行表土替代材料的开发,上覆岩层土壤的持水能力是选择表土替代材料的重要指标,对于指导排土场复垦具有重要意义。基于此选取了AP(Arya and Paris模型)、MV(Mohammadi and Vanclooster模型)和MVVG(MV model with the van Genuchten模型) 3种模型对锡林浩特矿区上覆岩层(L1-L5,共5层)土壤水分特征曲线与土壤有效含水量的预测精度。结果显示:MVVG对于土壤水分特征曲线(R^2=0.940)与有效含水量(R^2=0.7409)的预测精度均较好,AP对于土壤水分特征曲线的预测结果最好(R^2=0.950),且对于剖面有效含水量的预测趋势与实测值一致,但是有效含水量的预测值与实测值R^2较低(R^2=0.491),MV预测结果最差。AP模型对壤质沙土、砂之壤土和粉砂壤土的水分特征曲线预测效果好于MV和MVVG,但是各模型对沙土的预测预测效果均较差。除L5层,其余4层随着土壤层次深度的增加,其田间持水量、凋萎系数和有效水含量均呈减少趋势。L2-L4的有效水含量均低于L1(18%),且L4(8%)<L3(11%)<L2(15%)。研究结果显示AP和MVVG模型可以准确地预测研究区土壤水分特征曲线和水分常数,适合用于锡林浩特矿区上覆岩层土壤持水能力的预测。同时结果表明,L5层的有效含水量最大(20%),且土层较厚,具有在土地复垦过程中作为表土替代材料的潜力,而L2-L4可以考虑作为中和L5质地过黏的材料,使其土质更加接近腐殖层土壤(L1)。
文摘The aim of this paper is to analyse the possible impacts of proposed biofuel production at Hoedspruit in the Olifants River Catchment. These impacts are looked at in terms of availability of water and subsequent consequences on downstream users, especially the Kruger National Park that is mandated to conserve and protect biodiversity in all facets and fluxes in its area of jurisdiction. Based upon a review of experiences with biofuel production and impacts around the world, water availability for sugar cane production to support proposed biofuel production was found to be a problem in the region that has an average rainfall of only 450 mmper annum. The Olifants River system already has a deficit of about 200 million m3/a;hence the sustainability of the sugar cane based biofuel industry in the proposed area is questioned in this review. It is advised that alternative plants for the production of biofuel that may not consume large quantities of water be examined.
