Analysis on Status and Development Trend of Wind Erosion in Black Earth Region of Northeast China

In this paper,areas and main factors of wind erosion in black earth region of Northeast China were systematically analyzed,as well as the development trend of wind erosion in black earth region of Northeast China.In addition,development trend of wind erosion in black earth region of Northeast China was analyzed from the aspects of the geographic position,climatic change law in recent 40 years and effects of northeast sand land desertification on wind erosion in black earth region,which had provided references for the research and prevention of wind erosion in soil of black earth region of Northeast China.

Changes of spring wind erosion based on wind erosion climate factor in the black soil region of Northeast China

The dry and windy climate and low ground cover in spring in the black soil region of Northeast China make the soil strongly affected by wind erosion,which seriously threatens the food security and ecological security of this region.In this paper,based on the daily observation data of 124 meteorological stations in study area from 1961 to 2020,seasonal and monthly wind erosion climate factor(C)in spring(March to May)were calculated by using the method proposed by the Food and Agriculture Organization of the United Nations(FAO),the wind erosion characterization in spring were systematically analyzed based on C by various statistical analysis methods.The results showed that in the past 60 years,spring wind erosion climate factor(CSp)and monthly C of the whole region and each province(region)all showed highly significant decreasing trend,but they began to show rebounded trend in the middle or late 2000s.CSp of the study area showed a significant upward trend since 2008 with an increase of 4.59(10a)^(-1).The main contributors to this upward trend are the changes of C in March and in April.For the four provinces(regions),CSp in Heilongjiang,Jilin,Liaoning and eastern Inner Mongolia all showed rebounded since 2008,2011,2008 and 2009,respectively.The rebounded trend of CSp in eastern Inner Mongolia was the most obvious with a tendency rate of 11.27(10a)^(-1),and its mutation occurred after 1984.The rebound trend of CSp in Heilongjiang Province takes the second place,with a trend rate of 4.72(10a)^(-1),but there’s no obvious time mutation characteristics.The spatial characteristics of CSpand monthly C are similar,showing decreasing characteristics centered on the typical black soil belt of Northeast China.Compared with 1961-1990,in the period from 1991 to 2020,the proportion of high value areas(CSp>35,monthly C>10)has decreased to varying degrees,while the proportion of low value areas(CSp≤10,monthly C≤4)has increased.The trends of seasonal and monthly C in 82.2%~87.7%of the stations show significant decreases at 95%confidence level.CSp is closely related to wind speed at 2m height,temperature difference,minimum temperature and precipitation in the same period,of which the correlation between CSp and wind speed is the strongest,indicating that the main control factor for CSp in the study area is wind speed,but the impact of the change of temperature and precipitation on CSp cannot be ignored.

Sand-fixing Function under the Change of Vegetation Coverage in a Wind Erosion Area in Northern China

Using meteorological and remote sensing data and changes in vegetation cover during the wind erosion season in northern China, a revised wind erosion equation was applied to evaluate spatiotemporal variation in soil erosion and conservation since the 1990s, and to reveal the effects of the change of vegetation coverage on the wind erosion control service. The results showed that average soil erosion in northern China between 1990 and 2010 was 16.01 bil ion tons and was decreasing. The most seriously eroded areas were mainly distributed in large desert areas or low cover grasslands. Most wind erosion occurred in spring, accounting for 45.93% of total wind erosion. The average amount of sand ifxation service function for northern China between 1990 and 2010 was 20.31 billion tons. Given the influence of wind erosion forces, the service function for sand fixation cannot effectively highlight the role of sand ifxation from the ecosystem itself. The retention rate of service function for sand ifxation reveals the role of the ecosystem itself. The distribution characteristics of the soil retention rate are similar to vegetation cover, which shows a gradual decrease from southeast to northwest in the study area. Improved spring vegetation cover was observed mainly on the Loess Plateau, Qinghai-Tibet Plateau, in northern Hebei, eastern Inner Mongolia and northeast China after the implementation of ecosystem projects. The soil retention rate in most areas showed a signiifcant positive relationship with grassland vegetation in spring （r＆gt;0.7, p＆lt;0.01）. The increments of ecosystem service function for various ecological systems are different. Increments for the grassland ecosystem, forest ecosystem, farmland ecosystem and desert ecosystem are 2.02%, 1.15%, 0.99% and 0.86%, respectively.

Assessing changes in wind erosion climatic erosivity in China＇s dryland region during 1961-2012

China＇s dryland region has serious wind erosion problem and is sensitive to climate change due to its fragile ecological condition. Wind erosion climatic erosivity is a measure of climatic factors influencing wind erosion, therefore, evaluation of its intensity and response to recent climate changes can contribute to the understanding of climate change effect on wind erosion risk. Using the FAO equation, GIS and statistical analysis tools, this study quantified the climatic erosivity, analyzed its spatiotemporal variations, and detected the trend and sen- sitivity to climate factors during 1961-2012. The results indicate that mean annual climatic erosivity was 2-166 at 292 stations and 237-471 at 6 stations, with the spatial distribution highly in accordance with wind speed （R^2 = 0.94）. The climatic erosivity varied greatly over time with the annual variation （CV） of 14.7%-108.9% and monthly variation （concentration degree） of 0.10-0.71 in the region. Meanwhile, annual erosivity showed a significant down- ward trend at an annual decreasing rate mostly above 1.0%. This significantly decreasing trend was mainly attributed to the obvious decline of wind speed during the period. The results suggest that the recent climate changes were highly possible to induce a decrease of wind erosion risk in China＇s dryland region.

Wind Erosion Climate Change in Northern China During 1981-2016

Wind erosion is largely controlled by climate conditions.In this study,we examined the influences of changes in wind speed,soil wetness,snow cover,and vegetation cover related to climate change on wind erosion in northern China during 1981–2016.We used the wind erosion force,defined as wind factor in the Revised Wind Erosion Equation Model,to describe the effect of wind speed on wind erosion.The results show that wind erosion force presented a long-term decreasing trend in the southern Northwest,northern Northwest,and eastern northern China during 1981–2016.In the Gobi Desert,the wind erosion force presented for 1981–1992 a decreasing trend,for 1992–2012 an increasing trend,and thereafter a weakly decreasing trend.In comparison to wind speed,soil wetness and snow cover had weaker influences on wind erosion in northern China,while vegetation cover played a significant role in the decrease of wind erosion in the eastern northern China during 1982–2015.

1980—2016年中国北方风蚀气候侵蚀力的变化

随着修订风蚀方程(RWEQ)的提出,采用增加了冻结因子的气候因子(WF)表达风蚀气候侵蚀力更具有科学性和必要性。基于中国北方风蚀区157个气象站1980—2016年的观测数据,逐月计算了各站点气候因子,并探讨了气候因子时空分布变化特征及影响因素。结果表明:①1980—1997年,年气候因子值表现为快速下降,从940.46 kg/m下降到273.03 kg/m;而1998—2016年,年气候因子值表现相对稳定,在139.81~398.85 kg/m范围内波动。②春季气候因子值约占全年63%,其变化也显著高于其它季节,这也是土壤风蚀发生在春季的主要原因。③气候因子的高值区分布在新疆东部、青海西部、40°N以北的内蒙古中西部,这与气压中心和高大山体地形分布有关。

中国北方土壤风蚀问题研究的进展与趋势

土壤风蚀是中国北方土地退化的主要原因之一。国内土壤风蚀的研究工作相对比较薄弱，所取得的进展主要包括区域性的土壤风蚀分布地带性规律和不同时间尺度的准周期性规律，描述性的风蚀强度分级与危害评价，单因子风蚀过程的风洞实验，农田风蚀防治等方面。今后的研究趋势主要表现在土壤风蚀的物理本质、影响因素及发展动态的综合研究，土壤理化性质与表面性质对抗蚀性的影响及其与风蚀的反馈关系，土壤风蚀的基本过程及防治原理，土壤风蚀预报方程与数字模拟，土壤风蚀影响评价模型，土壤风蚀与土地利用以及全球变化的关系，各种观测与实验设备的研究等方面。

东北典型黑土区土壤风蚀环境分析

根据1951～2000年的日平均风速、气温和降水数据以及1980～2000年的沙尘暴资料，分析东北典型黑土区的风蚀环境。结果表明，东北典型黑土区6个气象站点1～5月平均气温50年来显著升高，1～5月总降水量没有明显变化趋势。嫩江年大风日数1980年以来比1950～1960年多，年沙尘暴日数也有所上升，土壤风蚀环境趋于严重；哈尔滨等5地风蚀环境减弱。典型黑土区土壤风蚀环境在整个东北地区处于中等状态。

东北黑土区土壤风力侵蚀及发展趋势分析

分析东北黑土区土壤风蚀区域及风蚀主要因子,并从黑土区所处的地理位置、区域近40年气候变化规律、东北沙地沙漠化对黑土区土壤风蚀的影响方面分析了东北黑土区土壤风蚀的发展趋势,为该区土壤风力侵蚀研究及防治提供依据。

黄土高原水蚀风蚀交错带沟岸灌木林地土壤水分变化

选择黄土高原水蚀风蚀交错带典型切沟,采用人工取样和中子仪测定研究了柠条坡地不同坡位土壤水分变化,明确了切沟对沟岸柠条林地土壤水分的影响范围,建立了土壤储水量与距沟沿不同距离之间的关系。结果表明:在黄土高原雨季(7～10月),天然降水对柠条坡地下位的补给深度达到了220cm,对坡地上位和中位的补给深度分别为180cm和160cm。在土壤剖面200cm深度范围内,坡下位土壤水分含量始终高于坡上位和坡中位,200cm深度以下,坡地上、中、下位土壤水分趋于一致。切沟对柠条林地土壤水分影响水平宽度达到3～4m,垂直深度达到6m以下。沟岸柠条坡地距沟沿不同距离土壤剖面储水量与沟沿距离间的关系可以用线性函数来表达。研究沟岸地距沟沿不同距离的土壤水分变化规律对沟岸地植被的恢复具有重要的科学意义。

地表覆被因子对华北寒旱区土壤抗风蚀力的影响

为了明晰不同类型土壤的抗风蚀力特征与华北寒旱区农田地表覆被因子减降土壤风蚀的效果,采用国家发明专利"土壤风蚀测定装置",通过室内模拟与田间实证研究,分析砂砾、垡片覆被以及耕作措施、残茬存留等地表覆被因子对不同类型农田土壤抗风蚀力的影响。结果表明,砂质栗钙土抗风蚀能力高于壤质草甸栗钙土,在连续吹蚀下地表土壤吹蚀量呈"L"形下降特征;砂砾与垡片覆被可显著增强土壤抗风蚀能力,随覆被度增加土壤吹蚀量呈近线性指数型下降特征。华北寒旱区多年免耕的燕麦留茬农田,地表土壤吹蚀量较传统翻耕田降低70.28%～88.42%,多年免耕的地表砂砾覆被对增强砂质栗钙土农田的抗风蚀力起重要作用;而留茬覆被的粗糙度效应对增强壤质草甸栗钙土农田抗风蚀力更为重要。壤质草甸栗钙土秋耕立垡覆被,较传统翻耕田地表土壤吹蚀量降低92.21%。研究表明,生物性残茬覆被、非生物性砂砾与垡片覆被具有显著提高土壤抗风蚀力效应;在华北寒旱区农田,燕麦留茬免耕覆被可显著降低土壤吹蚀量;对无植被存留条件的壤质草甸栗钙土农田,秋耕立垡覆被同样具有显著提高土壤抗风蚀力效果。

气流的垂直分布对地形雨落区的影响

从大气运动的基本方程出发, 讨论了华北地区太行山东侧低空东风气流背景下不同垂直分布气流对降水落区的影响。认为: 当垂直于山体的气流随高度减小时, 地形的作用表现为迎风坡上水平辐合, 造成气旋式涡度增加, 产生风场切变, 因此对迎风坡降水产生明显的增幅作用。当气流的垂直分布随高度增加时, 迎风坡方向表现为反气旋涡度增强, 而在背风坡方向产生辐合作用, 造成气旋式涡度增加, 发生风场切变。

陕北水蚀风蚀交错带土地利用变化及生态效应

在GIS技术支持下,分析陕北水蚀风蚀交错带1986—1997年土地利用时空变化,并运用马尔可夫模型对未来土地利用进行预测。采用生态弹性度,进行土地利用变化与生态效应研究。结果表明:区域1986—1997年土地利用类型变化主要是水田、旱地、其他林地、高覆盖草地、水体和建设用地增加,其他呈现减少趋势。土地利用的年均动态变化指数为2.4%,土地利用动态变化幅度远远高于绝对值变化量,土地利用类型内部转换非常剧烈。除水田、高覆盖草地和其他草地外的土地利用类型垂直重心下降。生态弹性度整体呈现下降趋势,但降解幅度减小。

中国土壤风蚀灾害发生的范围

从大尺度讨论土壤风蚀灾害,认为风蚀是侵蚀因子(风力、可蚀表面等)和抑制因子(植被、水分等)斗争的结果,风蚀灾害发生在侵蚀风和干燥无覆被土壤共同出现的时段,所以说气候决定风蚀灾害的范围。依据李世奎等的《中国农业气候区划》诊断各个农业气候区发生风蚀灾害的时间和强度,农业土壤和非农业土壤采用的方法相似,但指标体系不同,确定了中国土壤风蚀灾害发生的范围。结果表明中国土壤风蚀灾害主要发生在温带,范围涉及国土面积60.9%的广大地区,其中,东部季风农业气候大区和青藏高寒农业气候大区,土壤风蚀灾害以农业土壤为主;西北干旱农业气候大区,农业和非农业土壤均遭受风蚀灾害,而且风蚀程度也大于其他气候大区。

中国北方风蚀区风速变化时空特征分析

利用北方风蚀区155个气象站点1971—2015年平均风速数据,采用气候趋势分析、空间插值和小波分析等方法分析北方风蚀区平均风速的时空变化趋势。结果表明:近45 a来,北方风蚀区年平均风速为2. 70 m·s-1,呈明显减小趋势,其递减速率为0. 017 m·s-1·a-1(α=0. 001),1980s风速减小最快,1990s减小最缓慢,2010s风速出现增大趋势;我国北方风蚀区四季的平均风速均呈现下降趋势,下降速度春季>夏季>秋季>冬季(α=0. 001),不同年代不同季节风速变化存在较大差异,2010s除春季外其他季节风速均呈现增大趋势;空间分布上显示,风速变化幅度空间分布差异明显,北方风蚀区内的新疆西北部和东南部、青海、内蒙古中部和东北部、黑龙江以及吉林为风速降低较快的区域,甘肃东南部、宁夏、陕西和山西北部以及新疆的东北部和西部等地区是风速降低不明显的区域。春季和夏季风速降低较快的区域面积扩大,冬季和秋季风速降低较缓的区域扩大;平均风速存在多时间尺度的周期性结构特征,28 a时间尺度左右为风速变化的主周期,平均变化周期为18 a。

我国北方土壤风蚀力时空特征分析

利用1971—2011年北方风蚀区146个气象站的逐时风速资料,将5 m/s以上风速划分为和风、强风、大风、狂风4个等级,采用线性趋势分析、小波分析、M-K突变检验分析和空间相似度分析等方法分析了该地区不同等级土壤风蚀力时空分布特征,并讨论了与平均风速的时空相关性。结果表明,在空间分布上和风时数与强风时数空间分布相似,内蒙古锡林郭勒盟西部、乌兰察布和包头市北部为高值区,新疆天山山脉以南为和风和强风时数的低值区,除新疆天山以北,大部分地区大风和狂风时数极少; 4个等级风速平均时数季节变化规律均为春夏秋冬递减,风速等级越高,累计时数越少,季节与地区间的差异越小;在时间变化上,和风、强风、大风和狂风年总时数和四季时数均呈现减少趋势,四季间有明显差异;和风、强风和大风时数变化的主周期均为28年,而狂风时数变化的主周期为11年;和风与平均风速呈现较好的时空相关性,基本可以反映平均风速的时空变化。

重视旱地生态潜力完善生态农业建设──以浙江省金华市为例

作者认为，旱地分带集约经营是改善旱地生态环境的重要途径。以金华市为例，重点分析了旱地分带集约经营的功能：（１）能充分利用当地温、光、水、土等自然资源；（２）充分发挥边际效应；（３）提高总生物量产出能和经济量产出能；（４）有效地提高旱粮产量；（５）加速红壤旱地的培肥；（６）解决了养地与用地的矛盾。

1980—2015年风蚀影响下中国北方土壤有机质与养分流失时空特征

中国北方干旱/半干旱区是全球主要的沙尘源区之一,风蚀造成的沙尘排放可导致大量的土壤有机质(SOM)与养分流失,并通过传输与沉降过程对其进行空间再分配,对空气质量、气候变化、植被生长及生物地球化学过程等具有重要影响。本文利用WRF/Chem(Weather Research Forecasting with Chemistry)v3.7.1大气化学传输模型,对1980-2015年间中国北方沙尘排放及其引起的SOM、全氮(TN)与全磷(TP)的时空变化过程进行了精细化模拟,探究了中国北方风蚀引起的SOM、TN与TP养分流失的时空变化特征。结果表明:①1980-2015年来平均每年约有66.59 Tg的沙尘颗粒排放至大气;②沙尘排放具有较大的时空差异,沙尘排放源区主要集中在新疆东部、内蒙古西部的巴丹吉林沙漠和腾格里沙漠等地区;③每年因沙尘排放引起的SOM、TN和TP流失量分别约为0.07 Tg、0.004 Tg和0.005 Tg;④1980-2015年间中国北方沙尘排放及其引起的SOM、TN与TP的流失量具有较强的年际波动,未呈现显著的趋势性变化特征。本研究对于认知风蚀在碳循环与养分循环过程中的作用,以及对深入了解中国北方的土地退化机理具有重要意义。

典型黑土区坡耕地融雪、风力、降雨复合侵蚀效应

研究多营力作用的坡耕地复合土壤侵蚀过程机理,可为精确防治农田土壤侵蚀提供科学指导。本研究基于东北黑土区坡耕地每年11月到次年10月冻融、融雪、风力、降雨侵蚀营力的季节性交替,利用不同侵蚀营力叠加的模拟试验,分析了坡耕地融雪(1、2 L·min^(-1))、风力(12 m·s^(-1))、降雨(100 mm·h^(-1))多营力叠加的复合侵蚀过程,讨论了各营力叠加的侵蚀效应。结果表明:仅融雪侵蚀下,坡面融雪径流量的增加对坡面侵蚀量的影响大于其对坡面径流量的影响;融雪径流量从1 L·min^(-1)增加到2 L·min^(-1),径流强度增加2.7倍,而侵蚀强度增加4.0倍。融雪-风力双营力叠加侵蚀下,前期融雪侵蚀对后期坡面风蚀有抑制作用,当融雪径流量从1 L·min^(-1)增加到2 L·min^(-1),融雪侵蚀对风蚀量的抑制作用增强,导致后期风蚀量减小50%以上。前期风力侵蚀和融雪-风力叠加侵蚀均加剧了后期坡面降雨侵蚀,前期风力侵蚀导致后期坡面降雨侵蚀量增加24.5%,融雪-风力叠加作用在1和2 L·min^(-1)融雪径流量下使后期坡面降雨侵蚀量分别增加132.8%和465.4%。多营力叠加的复合侵蚀量并非相应的单营力侵蚀量之和,还存在各营力叠加的促进或抑制效应。融雪-风力叠加的侵蚀效应为抑制效应,风力-降雨双营力叠加和融雪-风力-降雨多营力叠加的侵蚀效应为促进效应。