林地开垦人为加速侵蚀的人工降雨试验研究

子午岭稍林区基本上代表了现代生态环境下的自然侵蚀。在该区选择典型流域进行林地与开垦地的人工降雨试验,分析评价自然侵蚀和人为加速度的演变与生态环境的关系。本试验选用了两组地形,三组雨强和两组土地处理。研究结果表明,天然次生林地基本上不发生土壤侵蚀,降雨和地形因素对侵蚀的作用不明显;林地开垦后,土壤侵蚀急剧发展,并随雨强和坡度的增大而增强。自然植被的破坏是人为加速的重要原因,侵蚀速率为自然侵蚀的数百倍以上。     

The extent and pattern of Eucalyptus regeneration in an agricultural landscape

The process of natural regeneration is critical for sustaining remnant native vegetation and the ecosystem services it supports. We quantified the extent and pattern of Eucalyptus regeneration within remnant vegetation in a fragmented agricultural landscape in south-eastern Australia. Eucalyptus regeneration was absent at 42% of sites. Using an information-theoretic approach, we explored 13 possible models of Eucalyptus regeneration across multiple scales. The explanatory variables in the four models with empirical support (and their summed Akaike weights) were: grazing intensity (1.0), native ground cover (0.99), remnant area (0.83), tenure (0.67), canopy cover (0.21) and vegetation type (0.11). Averaging across these four models we predicted that the probability of Eucalyptus regeneration was highest (0.95) in relatively unmodified remnant native vegetation, that is, remnant vegetation on public land where grazing was light and the understorey was dominated by native plants. In contrast, the predicted probability of Eucalyptus regeneration was lowest (0.12) in small remnants on private land where grazing was heavy. Our results suggest that a large proportion of all remnant native vegetation in this landscape will disappear under existing land management and farming practices. Reducing grazing pressure within intensively grazed remnants appears to be the single most effective management intervention that will mitigate this threat. This will require a shift in conservation priorities away from large, intact remnants where regeneration does not appear to be affected, to poorer quality remnants—often small remnants or scattered trees—where regeneration is typically absent.     

Eucalypt establishment in agricultural landscapes and implications for landscape-scale restoration

In south-eastern Australia large-scale re-establishment of woody vegetation is required to halt loss of biodiversity, land degradation and dryland salinisation. Revegetation is often undertaken via intensive replanting by tube-stock or seed although such methods are costly and can have limited biodiversity benefits. Regeneration from naturally dispersed seed is an alternative and cost-effective method of revegetation. Describing the relationships between broad-scale patterns of natural regeneration, landscape characteristics, climate and current and historical land use could assist in the development of regional revegetation strategies. In this paper we describe the results of a survey of eucalypt regeneration across 519 sites in grassy dry forests and grassy woodlands of central Victoria, Australia. Eucalypt regeneration was observed in 27% of all sites. The probability of eucalypt regeneration was reduced by intensive past land use (cultivation), regular livestock grazing, increasing distance to remnant trees and high cover of exotic annual vegetation. Even when these factors were taken into account, public land was predicted to have higher probabilities of supporting regeneration suggesting that a long-history of agriculture can limit future recruitment even when grazing is removed. Although the highest probability of regeneration was observed in ungrazed sites, regeneration also occurred under intermittent grazing regimes. Natural regeneration has potential to make considerable contributions to future tree cover in these landscapes. Scenario testing at three farms suggests that under current patterns of tree cover (2.7%), 40% of the total area has a high probability of supporting natural regeneration in the absence of livestock grazing. However, due to paddock tree decline this could be reduced to 18% of total farm area if no management action is taken in the next 30 years.     

生态脆弱矿区土地利用动态变化研究——以平朔矿区为例

基于平朔矿区1987年、1996年和2005年三期的TM影像,从土地利用数量变化模型、土地利用程度变化模型对矿区土地利用动态变化情况进行了分析。研究表明：（1）生态脆弱的平朔矿区自1987年以来耕地、林地面积呈减少趋势,而变化幅度最大的是已破坏待复垦地和已破坏复垦地,这主要是因为矿区生产建设占用了大量的耕地与林地,从而造成了许多待复垦地,同时由于受矿区土地复垦工程的影响,矿区内复垦地呈上升趋势;但是目前复垦后土地利用主要以林草地为主,所以无法拉动耕地面积的增长。（2）矿区土地利用程度综合指数显示上升态势,且土地利用程度变化率大于0,表明平朔矿区土地利用处于发展期。今后应加大对矿区的生态重建工作与土地复垦进程,保证矿区耕地平衡,促进矿区生态系统、经济系统和社会系统协调发展。     

不同植被下复垦土壤腐殖质与Cd形态的关系

[目的]揭示不同植被下土壤腐殖质与镉(Cd)形态的关系,为控制复垦土壤中Cd的活性提供理论依据。[方法]选择淮南市大通区煤矸石充填复垦区3种典型植被恢复模式下(模式A丁香+刺槐、模式B石楠+小巢菜、模式C臭椿+小巢菜)人工恢复7a的土壤,用tessier五步提取法和腐殖质修改法测定其Cd的化学形态及腐殖质组分,运用多元统计分析方法探讨复垦土壤中腐殖质与Cd的有效态间的相互作用。[结果](1)矿区复垦地C(臭椿+小巢菜)植被配置模式的土壤腐殖化程度较A,B模式高;(2)矿区复垦地C植被配置模式下Cd的可交换态含量显著低于其他2种配置模式;(3)矿区复垦区土壤中Cd的有效态与富里酸(FA)的含量显著正相关(p0.01)。[结论]通过适宜的植被模式C(臭椿+小巢菜)调节复垦土壤腐殖质的组成和性质,可以进而控制土壤镉的潜在生物有效性。     

Reclaiming the erosion susceptible landscape of the Italian badlands for arable cultivation

During the last 50 years substantial tracts of the Italian badlands have been reclaimed for arable cultivation. It is a process that involves modelling the degraded clay landscape with bulldozers, often resulting in steep, unstable slopes. This work investigates the stability of reclaimed land in these erosion susceptible environments. Aggregate stability is used to assess the soil's erodibility with the aim of determining those physicochemical properties that govern the potential for erosion. Regression analysis demonstrates that the most significant variables in determining soil erodibility are the percentage of organic matter and the exchangeable sodium percentage (ESP). Threshold values of 1–2 per cent organic matter and 15 per cent ESP are presented above and below which, respectively, the soils attain a degree of stability. Reclaimed land is on the borderline of these thresholds and therefore represents a potential erosion hazard. However, the stability of reclaimed land was significantly higher than that of the badland parent material, ascribable to a decline in the ESP. The results are supported by a series of soil crust experiments using simulated rainfall in the laboratory. This investigation has implications for land management and landscape conservation. If the organic matter content of reclaimed land is maintained and the ESP reduced, then, when used in combination with other soil conservation techniques, erosion will be minimized. However, this implies that the badland landscape, and its diverse ecology and morphology, may have been permanently lost to agriculture and, as such, should be recognized as a threatened Mediterranean landscape. © 1998 John Wiley & Sons, Ltd.     

省级土地整治规划中复垦规划方法与实证研究——以山西省为例

当前我国正在开展新一轮土地整治规划编制,而土地复垦规划作为土地整治规划的重要内容,因损毁土地基数不清、复垦潜力评价方法单一、复垦目标确定不够科学等问题严重影响土地复垦规划编制的科学性。该文采用统计分析法、典型调查法、实证分析法和类比法,结合山西省的具体情况,将损毁土地划分为煤炭、金属、砖瓦窑、公路、铁路、水利水电、自然灾毁7个类型,具体采用单位产量损毁系数测算法、典型调查法和统计分析法测算损毁土地面积、采用定性与定量结合的方法进行复垦适宜性评价、综合考虑多方面因素确定复垦目标。研究表明:山西省各类型损毁土地基数5.06×10⁵ hm²,待复垦损毁土地3.51×10⁵ hm²,损毁土地可复垦耕地潜力1.55×10⁵ hm²,规划期内确定土地复垦总目标3.0×10⁴ hm²。基于省级土地整治规划中损毁土地测算、复垦潜力评价及复垦目标确定的方法体系的探索,可为土地整治规划中复垦规划的编制、实施、监管和评价提供参考,具有重要的理论意义和实践指导意义。     

基于最小数据集的黄土高原矿区复垦土壤质量评价

矿产开发影响了土壤质量,特别是在黄土高原生态脆弱地区。通过植被恢复能够改善矿区复垦土壤质量。为了揭示矿区复垦土壤质量在植被恢复过程中的变化,该文以黑岱沟矿区排土场不同恢复年限不同植被类型、未复垦地和周边自然植被恢复区为研究对象,选取21项理化生指标作为总数据集(totaldataset,TDS),运用主成分分析(principal component analysis,PCA)结合Norm值构建评价指标最小数据集(minimum data set,MDS),通过非线性(non-Linear,NL)和线性(linear,L)两种评价方法对研究区土壤质量进行了评价。研究表明:黄土高原北部典型矿区复垦土壤质量评价指标MDS包括粉粒百分比、有机质、速效磷、钠吸附比和微生物碳;2种评价方法下,植被恢复均对复垦土壤质量指数(soil quality index,SQI)有了显著提升(P 0.05),复垦20 a灌木SQI高于复垦10 a灌木SQI,复垦12 a草本SQI高于复垦20 a草本SQI,然而所有复垦土壤SQI均未达到自然植被恢复土壤SQI;由于非线性土壤质量评价方法(SQI-NL)具有更大的土壤质量指数变化区间和变异系数,此外,在SQI-NL和线性土壤质量(SQI-L)评价两种方法下,MDS和TDS之间决定系数分别为0.911和0.866,因此,非线性土壤质量评价方法在该区域具有更好的适用性,并且最小数据集能够较准确地进行土壤质量评价。     

子午岭林区土壤侵蚀与生态环境关系的研究内容和方法

围绕子午岭天然次生林区土壤侵蚀与生态环境演变关系的研究主题,着重讨论研究背景,研究内容和研究方法。以典型调查和定位观测相结合,分析研究植被的破坏与恢复对土壤侵蚀的影响。通过建立大型径流场,动态监测不同地形部位林地与开垦地的土壤侵蚀演变过程,包括降雨、径流、入渗和侵蚀量的变化,细沟侵蚀和浅沟侵蚀的演变,土壤侵蚀与土壤退化的演变,坡、沟侵蚀的演变;同时结合进行野外人工降雨试验,林地和开垦地小气候对比观测等。初步建立了一整套宏观与微观相结合的研究体系,在黄土高原残留林区建立了土壤侵蚀与生态环境观测站,填补了国内空白。     

基于生态风险评价的采煤矿区土地损毁与复垦过程分析

煤炭开采和复垦活动带来强烈的地表变化和生态环境扰动。该文以山西省平朔矿区为例,通过构建评价模型分析采煤矿区的生态风险动态变化。通过采用最小损毁累积模型测算风险源累积损毁影响值,利用遥感影像结合野外实测数据计算生态脆弱度指数,得出矿区2001年和2010年矿区生态风险值,分析不同开采年份中矿区由于采矿和复垦活动带来的生态风险变化。结果表明:随着煤炭产量的增加,2010年土地损毁的累积影响范围比2001年增长了7 095.17 hm2;但是已复垦排土场的损毁累积危害下降明显,并且随着矿区扰动区域的东移,采矿对研究区西部的影响也在减弱。经过10年的土地复垦与生态重建措施,已复垦的排土场生态风险值呈下降趋势,生态系统趋于稳定。在采矿扰动区中,2001年处于中等风险及以下的区域占比为0.02%,到2010年为16.77%。特大型采煤矿区扰动范围较大,但是采后土地复垦有助于降低局部生态风险的影响。通过研究矿区土地损毁情况、复垦过程和复垦后的状态,分析不同区域生态风险的动态变化,可以为矿区的生态环境治理和区域发展规划提供参考,为矿区管理和相关决策提供科学依据。     

铜矿区水土流失治理及提高土壤肥力途径

通过对中条山铜矿区尾矿坝的复田试验结果表明，３０ｃｍ，６０ｃｍ，１００ｃｍ，３各复土厚度，其土壤保肥、抗旱能力不同。在种植绿肥和施化肥后，新复田土壤熟化度在１年内达到与老复田地（１５年）熟化程度同等肥力不同，作物产量也随复土厚并增加相应增加。     

中国近30a耕地变化时空特征及其主要原因分析

随着中国经济的快速发展和人口的不断增加,在各项建设占用大量耕地和生态退耕与环境保护措施的双重影响下,中国的耕地面积在持续减少。对中国耕地随时间变化规律的认识以及其空间分布变化趋势的把握已成为重要的研究内容,这对于研究区域粮食安全和区域可持续发展也有重要的指导意义。该文在中国长时间序列土地利用动态时空数据库的支持下,对中国1987年到2010年的耕地变化过程进行了全面分析,揭示了中国近30 a来耕地变化的时空特征,分析了其变化的主要原因。研究表明,自1987年以来,中国原有耕地不断减少,北方地区为主的新垦耕地持续增加。以2000年为转折点,1987年到2000年耕地总面积略有增加,2000年到2010年耕地总面积逐步减少,近30 a间,耕地总量相对稳定。比较而言,2000年以前的耕地增加速度明显高于2000年以后的耕地减少速度。到2010年全国耕地总面积呈南减北增、减少速率最快的区域集中于长江三角洲、珠江三角洲地区,而增加速率最快的区域集中在新疆、黑龙江以及内蒙古部分地区。建设用地对耕地的占用持续强烈并有加强趋势,生态建设占用耕地是生态脆弱地区耕地面积减少的主要原因,对耕地的占用比例仅次于建设用地。对草地、林地的开垦是全国新增耕地的主要来源,对未利用土地的占用有增强趋势,近年来,包括盐碱地;沼泽地,甚至是沙地、戈壁等未利用土地被改造成耕地,同时也会带来区域水资源和环境等方面的一系列问题,尤应慎重。     

煤炭基地复垦村庄土壤重金属污染生态风险评价

对煤炭基地的复垦村庄进行土壤重金属潜在生态风险评价,可以指出在村庄复垦中应该特别注意的物质,减少煤炭开采后有可能会造成土地污染并提高村庄复垦后的耕地质量。以山西省泽州县西郜村的压煤复垦村庄为研究区域,在分析了该地区土壤重金属含量的基础上,以山西省土壤重金属元素背景值为评价标准,采用潜在危害指数法对土壤重金属污染状况进行评价。研究结果表明,压煤复垦村庄不同层次土壤的综合污染程度范围为6.05~14.92,平均处于中等污染程度;从单个要素上来看,各种重金属污染系数平均值由高到低为:Hg > Pb > As > Cd > Cr,Hg属于较高的污染水平,其重金属潜在风险指数在75.9～275.19之间,有一半样点的潜在生态风险达到了中等程度;Hg潜在生态风险达到了较高污染程度,需要在复垦过程中进行治理。对煤炭基地复垦土壤重金属进行潜在生态风险评价,有助于掌握土壤重金属污染特征和分布规律,为复垦后耕地的重金属污染控制与修复提供一定的依据,促进土地资源的可持续利用。     

优化施肥方式对黄土高原新增耕地土壤有机质含量和团聚体特性的影响

[目的] 研究优化施肥对黄土高原地区新增耕地土壤质量和作物产量的影响,为新增耕地土壤建立合理的优化施肥处理和区域新造土地的健康可持续发展提供理论依据。[方法] 通过盆栽种植试验,评估有机肥处理（OF）、有机肥配施化肥处理（NP）、常规施肥处理（CF）对新增耕地土壤团聚体数量、结构稳定性、有机质含量和玉米产量的改良效应。[结果] CF处理下新整治耕地土壤有机质含量最低为7.08 g/kg,土壤水稳性大团聚含量低,结构稳定性差。与CF处理相比,优化施肥方式下的OF和NP处理显著提高了新增耕地土壤有机质含量和玉米产量（p<0.05）,>0.25 mm粒级大团聚体含量和团聚体稳定性显著提升,其中OF处理对新整治耕地土壤团聚体数量和稳定性的改善效果最佳。在0—10 cm土层,OF和NP处理下土壤有机质含量分别为12.67,11.79 g/kg,比CF处理分别提高了46.2%和36.1%。OF处理下水稳性团聚体MWD,GMD,R_0.25值分别比CF处理高了62.5%,21.4%和148.3%,分形维数比CF处理降低了1.7%;NP处理下水稳性团聚体MWD,GMD,R_0.25值分别比CF处理高了18.8%,3.6%和40.9%,分形维数比CF处理降低了0.4%。在10—20 cm土层,OF和NP处理下土壤有机质含量、团聚体数量和结构稳定性也得到一定的提升。土壤有机质含量与团聚体平均重量直径（MWD）、几何平均直径（GMD）呈显著正相关关系（p<0.001）。[结论] 优化施肥是有利于提升新整治耕地土壤结构稳定性、保肥特性和土地生产力的有效措施。     

Sand-dust storms in and around the Ordos Plateau of China as influenced by land use change and desertification

The occurrence of sand-dust storms induced by wind erosion is a process that accelerates land degradation and can also be considered as an indicator of desertification. Thus, it is of significance both in theory and in practice to reveal the interaction between these two phenomena. Based on data from the Ordos Plateau and its surrounding areas, a study has been made of the effect of land degradation and land use changes on sand-dust storms. In this study, we report a non-linear relationship between sand-dust storm frequency and the index of land degradation (I_d), which is defined as the percentage of the area of total land that is desertified. Using this non-linear relationship, a threshold at I_d = 30% is established such that, when I_d < 30% sand-dust storm frequency does not change with increasing I_d but when I_d > 30%, sand-dust storm frequency increases rapidly. This existence of such a threshold means that sand-dust storm frequency would increase abruptly when the human-induced I_d exceeds 30%. The time series of annual number of sand-dust storm days in the neighbouring area has been compared to the time series in the annual number of strong wind days and the time series in the area of cultivated land in Yikezhao Meng, and a multi-regression equation has been established. Based on the equation, the relative contributions of the variations in land use and in annual number of strong wind days to the variation in annual number of sand-dust storm days have been estimated as 59.7% and 40.3%, respectively, indicating that the frequency of sand-dust storms may be effectively decreased by reducing the area of cultivated land and restoring the natural steppe vegetation in ecologically fragile areas in arid and semi-arid climates.     

霍林河流域湿地土地利用/土地覆被类型的渐变过程

研究了霍林河流域自然湿地和人工湿地的面积动态变化以及土地利用/覆被变化过程——渐变过程,结果表明1986～2000年期间自然湿地的面积呈缩减变化,而人工湿地面积则呈增长变化;1986～1996年期间除河流湿地没有发生渐变过程外,其它类型湿地之间普遍存在着渐变过程,其中沼泽的渐变过程最为显著,表现为大幅度缩减,而滩地、湖泊、水库坑塘和水田在渐变过程中则表现为增加变化。1996～2000年期间各类型湿地之间普遍存在着渐变过程,但不同的是,沼泽湿地面积在渐变过程中表现为大幅度增加,而河流、滩地、湖泊和水库坑塘却表现为大幅度缩减;同时沼泽、滩地、湖泊以及水库坑塘在此期间都有向水田发生转变,表明人类的活动范围在不断的扩展,对湿地的开垦力度也在不断加强。     

矿区泥浆泵复垦土壤物理特性的时空演化规律

以徐州矿区为例，对不同时期不同层次泥浆泵复垦土壤进行了监测和分析，揭示了泥浆泵复垦土壤物理特性的时空演化规律。结果表明：与正常农田相比，泥浆泵复垦土壤质地表层偏粘性，底层偏砂性；土壤容重表层偏高，底层偏低；土壤团粒结构含量偏低。随着复垦后时间的推移，泥浆泵复垦土壤不断熟化，表现为土壤容重表层不断降低和底层不断增加，以及土壤团粒结构不断增加的演化特征，后者则以０．５－３ｍｍ团粒结构的形成速度较快。至复垦后第１３年泥浆泵复垦土壤容重和团粒结构基本接近正常农田的水平。     

Spatiotemporal evolution and assembly processes of ammonia-oxidizing prokaryotic communities in 1 000-year-old coastal reclaimed soils

Coastal marshes are transitional areas between terrestrial and aquatic ecosystems. They are sensitive to climate change and anthropogenic activities. In recent decades, the reclamation of coastal marshes has greatly increased, and its effects on microbial communities in coastal marshes have been studied with great interest. Most of these studies have explained the short-term spatiotemporal variation in soil microbial community dynamics. However, the impact of reclamation on the community composition and assembly processes of functional microbes (e.g., ammonia-oxidizing prokaryotes) is often ignored. In this study, using quantitative polymerase chain reaction and the Ion S5^TM XL sequencing platform, we investigated the spatiotemporal dynamics, assembly processes, and diversity patterns of ammonia-oxidizing prokaryotes in 1 000-year-old reclaimed coastal salt marshes. The taxonomic and phylogenetic diversity and composition of ammonia oxidizers showed apparent spatiotemporal variations with soil reclamation. Phylogenetic null modelling-based analysis showed that across all sites, the archaeal ammonia-oxidizing community was assembled by a deterministic process (84.71%), and deterministic processes were also dominant (55.2%) for ammonia-oxidizing bacterial communities except for communities at 60 years of reclamation. The assembly process and nitrification activity in reclaimed soils were positively correlated. The abundance of the amoA gene and changes in ammonia-oxidizing archaeal and bacterial diversities significantly affected the nitrification activity in reclaimed soils. These findings suggest that long-term coastal salt marsh reclamation affects nitrification by modulating the activities of ammonia-oxidizing microorganisms and regulating their community structures and assembly processes. These results provide a better understanding of the effects of long-term land reclamation on soil nitrogen-cycling microbial communities.     

宁夏黄土区不同植物群落土地利用方式对土壤质量的影响

本文研究了宁夏南部山区典型植物群落土地不同利用方式下土壤质量的变化。结果表明:（1）典型长芒草群落土地,开垦地比封禁地土壤有机质、全氮、全磷、速效氮、速效磷、速效钾养分含量明显降低,降低幅度分别为19.5%、20.1%、17.6%、13.0%、77.8% 和47.5%。脲酶活性为开垦地封禁地,蔗糖酶则表现为封禁地开垦地,中性磷酸酶差异不明显。（2）铁杆蒿群落土地三种利用方式下:放牧地土壤有机质、全氮、全磷、速效钾等养分含量较封禁地与开垦地有一定幅度的增加;放牧地的土壤脲酶、蔗糖酶和中性磷酸酶活性均高于封禁和开垦的同土层土壤,封禁地的脲酶和蔗糖酶次之,开垦地的脲酶和蔗糖酶活性最小,开垦地的中性磷酸酶活性高于封禁地。脲酶活性在土层之间变化较小,最高为放牧地表层177.6 mg/(kg.h),最低为开垦地表下层114.5 mg/(kg#8226;h),蔗糖酶活性层次之间变化明显,其中放牧地表层为表下层的3倍左右。长芒草群落土壤表层各级微团聚体表现为封禁地远大于开垦地,铁杆蒿群落土地不同利用方式下各级微团聚体表现不同,结构系数表现为表层表下层,保持率则为表层表下层。结构系数与保持率均表现为封禁地放牧地开垦地。（3）在轻度放牧条件下,土壤养分状况、酶活性有所提高,但土壤微团聚体中的结构系数与保持率则明显降低。     

浑善达克沙地境内沙地榆的自然更新

对不同生境下浑善达克沙地榆(Ul mus pumila L.var.sabulosa J.H.Guo Y.S.Li)林下幼苗的密度、生长情况及林缘、单株下幼苗扩散分布进行了野外调查研究,运用种群生态学方法及数理统计方法分析了其更新规律。结果表明,浑善达克沙地榆幼苗的密度为流动沙丘半固定沙地固定沙地;固定沙地、流动沙丘幼苗生长较差且流动沙丘幼苗死亡现象严重,半固定沙地幼苗生长较好更适于沙地榆的更新;幼苗主要集中分布于距林缘20m范围内,20m外幼苗密度显著降低;风向对浑善达克沙地榆的分布有较大的影响。