云贵高原生态恢复空间分异及其影响因素

全面深入评估生态恢复效益并明晰其自然—社会经济驱动机制,对维护区域生态安全、实现可持续发展目标具有重要意义。然而,在区域尺度量化分析时间序列生态恢复程度及其影响因素的案例研究较少。以云贵高原为研究对象,基于多源遥感数据,运用模型模拟、时间序列趋势分析等方法,从生态系统宏观结构、质量和服务3个层次评估了2000-2019年云贵高原地区的生态恢复效益,使用随机森林方法探究了生态恢复的自然-社会经济影响因素。结果表明:(1)近20年云贵高原地区生态系统宏观结构变化明显,主要表现为森林、草地和聚落生态系统面积的增加,以及农田生态系统面积的减少;(2)生态系统质量和服务恢复态势总体稳定向好,部分区域转差;(3)云贵高原地区生态系统的恢复程度整体较高。其中,恢复程度中等及以上的地区占总面积的35.84%;生态恢复程度有所转差及以下的面积最少,占总面积的7.54%;(4)地形、气候和土壤等生态本底特征是云贵高原地区生态恢复最重要的影响因素;在局地尺度,造林面积、人口密度年变化率等人类活动因子对生态恢复具有关键的作用。未来生态系统管理和生态恢复工程的实施应综合考虑区域生态背景和尺度效应,因地制宜采取恢复措施,以实现生态与社会经济发展的共赢。

长江上游生态状况变化及其服务功能权衡与协同

利用地面和遥感数据,采用GIS分析与模型模拟等方法,计算并分析了2000—2019年长江上游生态系统宏观结构、生态系统质量和生态系统服务的时空变化状况,利用相关分析法定量评估了生态系统服务的权衡与协同关系,并讨论了生态系统变化对生态系统服务的影响。结果表明:(1)长江上游聚落生态系统面积增加显著,农田和荒漠面积明显减少,陆地生态系统以草地、森林和农田之间转换为主。(2)2000—2019年,长江上游生态系统质量和服务总体稳定向好,部分区域转差。植被固碳量整体呈增加趋势,局部降低,多年递增速率为1.65 Tg/a;土壤保持服务功能呈波动中上升趋势,多年递增速率为2.20 t hm^(-2)a^(-1);水源涵养服务功能轻微下降,部分年际间变化较大。(3)长江上游生态系统的植被固碳与土壤保持、水源涵养与土壤保持之间以协同关系为主,植被固碳与水源涵养之间的权衡和协同关系比例相近。(4)气候是影响生态系统服务变化的主导因素,人类活动影响生态系统服务变化,最终改变生态系统服务之间的协同与权衡关系。

基于物质量评估的贵州南部地区生态系统服务及其县域差异比较

以贵州南部地区为例,对涵养水源、固碳释氧、净化大气环境、保育土壤和生物多样性保护5个功能类别共14项指标的生态系统服务物质量进行了区域尺度和县域尺度上的估算。结果表明：（1）贵州南部地区林草生态系统年调节水量145.41×10~8m^3,年固碳量和年释氧量分别为819.96×10~4t和1 538.48×10~4t,年提供负离子达2.32×10^（25）个,年吸收二氧化硫（SO_2）、氟化物（F）、氮氧化物（NO_X）分别达到58.07×10~4t、1.29×10~4t和7.76×10~4t,年滞尘量1.04×10~8t,年固土总量9.07×10~8t,年保育N、P、K以及有机质量分别为184.81×10~4t、59.26×10~4t、1 138.80×10~4t以及4 045.85×1~04t,平均生物多样性综合评价指数为54.87;（2）各类生态系统服务物质量均表现出明显的空间分布趋势,整体表现为东高西低,南高北低;（3）县域尺度上,黎平县、榕江县、从江县和望谟县提供的生态系统服务物质量最多,普定县、三穗县、长顺县和丹寨县则最少;就生态系统服务供给能力而言,雷山县、望谟县、榕江县和从江县最强,兴仁县、普定县、长顺县和贞丰县则最弱。

中国三北防护林工程第二阶段生态效益综合评价

【目的】三北防护林工程第二阶段(2001—2020年)实施以来取得了巨大的生态效益,但局部地区仍然存在问题,甚至出现生态退化。以生态系统结构、质量、服务为核心,综合定量评价工程实施前后生态系统变化,厘清第四期(2001—2010年)和第五期(2011—2020年)工程对生态系统恢复的影响,为后续三北工程的滚动实施提供科学和有针对性的理论依据。【方法】基于“历史动态本底—恢复现状—恢复指数”的生态工程生态效益综合评估方法,以遥感解译反演和模型估算结果为基础,构建生态系统宏观结构变化指数(EMSCI)、质量变化指数(EQCI)、服务功能变化指数(ESCI)和生态系统恢复指数(ERI),全面评估三北防护林工程区生态系统类型结构、质量和关键服务功能的时空格局变化。利用空间叠加分析功能,厘清工程实施期间的生态系统变化过程,定量评价生态系统恢复程度。【结果】1)在三北防护林工程第二阶段,生态系统类型显著变动,整体动态度为12.22%,森林覆盖率持续增加,森林面积占比10.18%,且第四期增量(1.60万km^(2))大于第五期增量(0.69万km^(2))。2)生态系统质量显著改善,平均植被覆盖度和平均植被净初级生产力分别增加了3.77%和82.33 gC·m^(-2) a^(-1),增长率为24.50%和34.96%。生态系统质量持续转好面积占比20.15%。3)与本底期相比,生态系统服务功能全面提升,单位面积水源涵养量增长1.25万m^(3)·km^(-2),单位面积植被固碳量增长134.19 gC·m^(-2) a^(-1),单位面积土壤保持量增长6.76 t·hm^(-2) a^(-1),单位面积防风固沙量增长9.81 t·hm^(-2) a^(-1),分别提升了45.89%、34.96%、74.29%和24.96%。单位面积水蚀模数增加23.88%(因为近年来年均降水量比前期增加,造成侵蚀量和保持量均有所增加),风蚀模数下降25.58 t·hm^(-2) a^(-1),风沙侵蚀危害程度降低46.49%。生态系统服务功能持续转好面积占比15.83%。4)生态系统恢复状况良好,持续转好和保持稳定区域面积占比为21.95%和20.29%。【结论】三北防护林工程区经第二阶段多期连续实施重点生态工程,已取得显著成效。东北华北平原农区、内蒙古高原中部风沙区和黄土高原丘陵沟壑区的生态系统恢复良好,森林覆盖率提高,平均植被覆盖度增加,平均植被净初级生产力提高,单位面积水源涵养量、植被固碳量、土壤保持量和防风固沙量等生态系统服务功能明显转好。但西北荒漠区生态系统仍较脆弱,整体生态系统状况并未得到有效改善。在天山附近、准葛尔盆地、柴达木盆地、南疆盆地固沙农牧区、坝上高原、内蒙古西部荒漠半荒漠草原等生态系统脆弱区域,森林面积增长放缓,草地面积减少,荒漠面积增加,防治草地沙漠化仍为未来工程实施的重点。

Cluster analysis on summer precipitation field over Qinghai-Tibet Plateau from 1961 to 2004

The summer day-by-day precipitation data of 97 meteorological stations on the Qinghai-Tibet Plateau from 1961 to 2004 were selected to analyze the temporal-spatial distribution through accumulated variance,correlation analysis,regression analysis,empirical orthogonal function,power spectrum function and spatial analysis tools of GIS.The result showed that summer precipitation occupied a relatively high proportion in the area with less annual precipitation on the Plateau and the correlation between summer precipitation and annual precipitation was strong.The altitude of these stations and summer precipitation tendency presented stronger positive correlation below 2000 m,with correlation value up to 0.604（α=0.01）.The subtracting tendency values between 1961-1983 and 1984-2004 at five altitude ranges（2000-2500 m,2500-3000 m,3500-4000 m,4000-4500 m and above 4500 m）were above zero and accounted for 71.4%of the total.Using empirical orthogonal function, summer precipitation could be roughly divided into three precipitation pattern fields：the Southeast Plateau Pattern Field,the Northeast Plateau Pattern field and the Three Rivers＇ Headstream Regions Pattern Field.The former two ones had a reverse value from the north to the south and opposite line was along 35°N.The potential cycles of the three pattern fields were 5.33a,21.33a and 2.17a respectively,tested by the confidence probability of 90%.The station altitudes and summer precipitation potential cycles presented strong negative correlation in the stations above 4500 m,with correlation value of-0.626（α=0.01）.In Three Rivers Headstream Regions summer precipitation cycle decreased as the altitude rose in the stations above 3500 m and increased as the altitude rose in those below 3500 m.The empirical orthogonal function analysis in June precipitation,July precipitation and August precipitation showed that the June precipitation pattern field was similar to the July＇s,in which southern Plateau was positive and northern Plateau negative.But positive value area in July precipitation pattern field was obviously less than June＇s.The August pattern field was totally opposite to June＇s and July＇s.The positive area in August pattern field jumped from the southern Plateau to the northern Plateau.

Effects of Afforestation on Carbon Storage in Boyang Lake Basin,China

By using field survey data from the sixth forest inventory of Jiangxi Province in 2003,the biomass and carbon storage for three studied species(Pinus massoniana,Cunninghamia lanceolata,and Pinus elliottii)were estimated in Taihe and Xingguo counties of Boyang Lake Basin,Jiangxi Province,China.The relationship between carbon density and forest age was analyzed by logistic equations.Spatio-temporal dynamics of forest biomass and carbon storage in 1985–2003 were also described.The results show that total stand area of the three forest species was 3.10×105ha,total biomass 22.20 Tg,vegetation carbon storage 13.07 Tg C,and average carbon density 42.36 Mg C/ha in the study area in 2003.Carbon storage by forest type in descending order was:P.massoniana,C.lanceolata and P.elliottii.Carbon storage by forest age group in descending order was:middle stand,young stand,near-mature stand and mature stand.Carbon storage by plantation forests was 1.89 times higher than that by natural forests.Carbon density of the three species increased 8.58 Mg C/ha during the study period.The carbon density of Taihe County was higher in the east and west,and lower in the middle.The carbon density of Xingguo County was higher in the northeast and lower in the middle.In general,the carbon density increased with altitude and gradient.Afforestation projects contribute significantly to increasing stand area and carbon storage.Appropriate forest management may improve the carbon sequestration capacity of forest ecosystems.

Identification of Dominant Climate Variables on Spatiotemporal Variation in Reference Evapotranspiration on the Loess Plateau,China

Reference evapotranspiration(ET_(0))is a vital component in hydrometeorological research and is widely applied to various aspects,such as water resource management,hydrological modeling,irrigation deployment,and understanding and predicting the influence of hydrologic cycle variations on future climate and land use changes.Quantifying the influence of various meteorological variables on ET_(0) is not only helpful for predicting actual evapotranspiration but also has important implications for understanding the impact of global climate change on regional water resources.Based on daily data from 69 meteorological stations,the present study analyzed the spatiotemporal pattern of ET_(0) and major contributing meteorological variables to ET_(0) from 1960 to 2017 by the segmented re-gression model,Mann-Kendall test,wavelet analysis,generalized linear model,and detrending method.The results showed that the annual ET_(0) declined slightly because of the combined effects of the reduction in solar radiation and wind speed and the increase in vapor pressure deficit(VPD)and average air temperature in the Loess Plateau(LP)during the past 58 yr.Four change points were detected in 1972,1990,1999,and 2010,and the annual ET_(0) showed a zigzag change trend of‘increasing-decreasing-increasing-decreasing-increasing’.Wind speed and VPD played a leading role in the ET_(0) changes from 1960 to 1990 and from 1991 to 2017,respectively.This study confirms that the dominant meteorological factors affecting ET_(0) had undergone significant changes due to global climate change and vegetation greening in the past 58 years,and VPD had become the major factor controlling the ET_(0) changes on the LP.The data presented herein will contribute to increasing the accuracy of predictions on future changes in ET_(0).

2000-2020年长江流域生态系统服务变化及其权衡协同关系

[目的]长江是中国重要的生态安全屏障,开展长江流域生态系统服务时空变化及土地利用驱动力分析,有助于该区域生态与经济协调发展。[方法]本文基于卫星遥感数据,采用RUSLE模型、InVEST模型等计算了土壤保持量、产水量和固碳量,采用Sen趋势法、热点分析方法等进行了生态系统服务变化分析,采用偏相关法分析了服务之间的权衡协同关系变化,并从土地利用变化角度剖析了生态系统服务变化原因。[结果](1)2000-2020年长江流域年均土壤保持量、产水量和固碳量变化趋势度分别为1.75 t/(hm^(2)·a)、-1.33×10^(3) m^(3)/(km^(2)·a)和1.62 gC/(m^(2)·a),除产水在部分区域呈减少趋势外,其他服务均普遍呈增加趋势,生态系统服务热点区域总体面积有所扩大,特别是以固碳和产水服务为主的热点区域。(2)土壤保持和固碳、固碳和产水以协同关系为主,土壤保持和产水以不显著权衡关系为主,土壤保持和产水由协同关系转为权衡关系,土壤保持和固碳一直为协同关系且强度呈加强趋势,固碳和产水一直为协同关系且强度呈波动态势。(3)不同土地利用变化对生态系统服务的影响不同,耕转林对土壤保持服务积极影响较大,耕转草对固碳服务积极影响较大,草转耕对产水服务消极影响较大。(4)土地利用变化影响生态系统服务之间的关系,耕转林草时,土壤保持、产水和固碳两两服务之间趋于协同,林草转耕时则趋于权衡。[结论]2000-2020年长江流域生态系统服务总体有所提升,土地利用变化中林草面积的增加对生态系统服务提升及服务之间协同发展有积极作用,国土空间开发和生态保护用地之间的博弈影响生态系统服务的动态变化,考虑该区域经济发展的重要性,需平衡发展与保护的关系,进行绿色可持续发展。

长江上游地区生态恢复程度及植被恢复潜力空间差异分析

长江上游地区是长江流域生态安全屏障关键区,是长江流域土壤保持和水源涵养的重要功能区,对中国西部地区和长江经济带的发展起着重要作用,定量分析长江上游地区生态恢复程度及植被恢复潜力,对于保障国家生态安全具有重要意义。本文基于气象、土壤、遥感等多源数据,结合模型模拟从生态系统质量和生态系统服务两方面量化了2000—2019年长江上游地区生态恢复程度及空间差异,厘定了气候要素与人类活动对长江上游地区生态系统变化的贡献程度,并探究了植被恢复潜力,结果表明:①长江上游地区生态系统质量整体向好发展,植被覆盖度和植被净初级生产力均呈稳定增加态势,增速分别为0.15%/a、3.77 gC/(m^(2)·a);生态系统服务增减有所差异,土壤保持量呈逐年增加趋势,增速为2.72 t/(hm^(2)·a),水源涵养量呈逐年下降趋势,年均减少2.37万m^(3)/km^(2)。②生态系统整体呈恢复转好态势,但仍存在面积占9.76%的区域生态系统状况变差。生态恢复程度较高的区域主要分布在长江上游地区的东部和南部金沙江流域与乌江流域交界区域。较明显转差区域主要分布在西部的金沙江流域。③气候要素是影响长江上游地区生态系统变化的主要因素,气候要素和人类活动对生态系统变化的贡献率分别为78.78%和21.22%。④长江上游地区森林、草地、荒漠生态系统仍有8.73%的恢复潜力,位于金沙江流域和岷-沱江流域的青藏高原部分区域恢复潜力较大。本研究通过定量化评估生态恢复状况及植被恢复潜力,可为长江上游地区的生态环境建设和管理提供决策参考。

2000-2019年中国重大生态工程生态效益遥感评估

We propose a theoretical framework for assessing the ecological benefits provided by key national ecological projects in China over the past 20 years.A dataset consisting of six primary indicators and nine secondary indicators of ecosystem structure,ecosystem quality,and ecosystem services for 2000-2019 was generated using ground survey and remote sensing data.Ecological benefits were quantitatively evaluated following the implementation of these projects in China.Areas with medium,relatively high,and high degrees of ecological restoration accounted for 24.1%,11.9%,and 1.7% of the national land,respectively.Degrees of ecological restoration were higher in areas with greater numbers of ecological projects.Areas with relatively and absolutely high degrees of ecological restoration were mainly concentrated in the Loess Plateau,the farming-pastoral zone of northern China,the Northeast China Plain,and an area spanning the borders of Sichuan,Yunnan,Guizhou,Chongqing,and Hunan.The relative contributions of climatic factors and ecological projects to changes in vegetation net primary productivity were 85.4% and 14.6%,respectively,and the relative contributions of climatic factors and ecological projects to changes in water erosion modulus were 69.5% and 30.5%,respectively.The restoration potential of national vegetation coverage was 20%,and the restoration potential percentage of forest and grassland vegetation coverage was 6.4% and 23%,respectively.Climatic conditions can inhibit ecological restoration.Areas with relatively high and high degrees of ecological restoration were mainly distributed in areas with an average annual temperature greater than 0℃ and annual precipitation greater than 300 mm.Therefore,the limitations associated with climate conditions require consideration during the implementation of national ecological projects.The implementation of combined measures should be emphasized,and the benefits of ecological investment funds should be maximized.

无人机遥感的大型野生食草动物种群数量及分布规律研究

以黄河源玛多县为研究区,利用无人机分别于2017年冬春季开展了航拍调查,航拍有效面积达326.6 km2,获取影像23784张,建立了藏野驴、藏原羚、岩羊等野生动物,以及牦牛、藏羊和马等家畜的无人机图像解译标志库。通过人机交互方式解译,获取调查样带内的种群数量:藏野驴的样带密度为1.15只/km2,藏原羚为0.61只/km2,岩羊为0.62只/km2,家养牦牛为4.12只/km2,家养藏羊为7.34只/km2,马为0.06只/km2。利用冷暖季草场的估算方法,通过地面同步调查验证、统计数据验证,估算出玛多县藏野驴、藏原羚和岩羊,以及家牦牛、藏羊和马的种群数量为:藏野驴17109头,藏原羚15961只,岩羊9324只,牦牛70846头,藏羊102194只,马1156匹。大型野生食草动物藏野驴、藏原羚和岩羊总计8.57万羊单位;家畜藏羊、牦牛和马总计38.90万羊单位;大型野生食草动物和家畜总计47.5万羊单位。大型野生食草动物羊单位数量与家畜羊单位数量之比为1∶4.5。并分析了野生动物分布密度与栖息地生境因子的关系:藏野驴偏好选择高程4200—4400 m,坡度为2°—5°,离农村居民点距离1—2 km和4—5 km,离水源距离小于1 km,离公路距离2—3 km和4—5 km的范围内,草地盖度60—80%。藏原羚偏好选择高程4100—4200 m和4400—4500 m,坡度为大于5°,草地盖度80%以上,离农村居民点距离2—3 km,离水源距离小于1—2 km,离公路距离小于1—2 km和4—5 km的范围内。岩羊偏好选择高程4100—4200 m,坡度为大于5°,草地盖度较低,离农村居民点距离小于1 km,离水源距离小于1—2 km,离公路距离大于5 km的范围内。与传统的地面调查方法相比,基于无人机遥感的大型野生食草动物种群数量调查,具有快速、经济、可靠等优点,为今后野生动物调查提供了一种有效、可靠的技术途径。

2000—2019年中国重大生态工程生态效益遥感评估

本文提出了重大生态工程实施生态效益评估理论框架,在选取生态系统宏观结构、生态系统质量和生态系统服务3大类、6个一级指标和9个二级指标的基础上,利用地面和遥感数据,结合模型模拟,生成了2000—2019年长时间序列评估指标参数数据集,定量评估了中国重大生态工程实施20年后的生态效益。结果表明:生态恢复程度中等、较高和高的区域面积分别占全国国土面积的24.1%、11.9%和1.7%,生态工程实施数量越多的地区,生态恢复程度越高,生态恢复程度较高和高的区域主要集中在黄土高原、北方农牧交错带、东北平原、川滇黔渝湘结合部等地区;气候因素和生态工程对植被净初级生产力变化的贡献率分别为85.4%和14.6%,对水蚀模数变化的贡献率分别为69.5%和30.5%;中国植被覆盖度有20%的恢复潜力,森林植被覆盖度恢复潜力为6.4%,草地植被覆盖度恢复潜力为23%;气候条件是生态恢复的重要限制因素,生态恢复程度较高和高的区域主要分布在年均温大于0℃和年降水量大于300 mm的地区。因此,重大生态工程的部署,应充分考虑气候条件的限制性,避免实施单一生态工程或单一生态恢复措施,充分发挥生态工程组合措施的综合效应,提高生态投入资金的最大效益。

三江源地区草地退化对土壤含水量的影响

【目的】研究草地退化对青海三江源地区土壤含水量的影响,为草地生态系统的综合监测与评估提供科学参考。【方法】根据遥感解译数据,得到20世纪70年代以来三江源地区草地退化的时空特征,结合不同土壤类型、不同退化等级下的孔隙度实测数据,利用空间分布替代时间演替的方法得到不同时段土壤饱和含水量的时空变化,分析该区草地退化与土壤饱和含水量的关联程度。【结果】20世纪70年代中后期至2004年,三江源地区草地退化现象持续发生;2004—2012年,该区草地得到了一定程度的恢复。20世纪70年代中后期至2004年,三江源地区草地土壤饱和含水量减少了45.58亿m3;2004—2012年,草地土壤饱和含水量减少了1.50亿m3。【结论】尽管草地退化情况略有减轻,但草地土壤饱和含水量表现出持续减少的现象。植被退化是三江源地区土壤退化的直接原因,由其引起土壤理化性状的改变,进而影响土壤持水性。

黄河源区放牧家畜数量及空间分布无人机遥感调查

黄河源区拥有独特的生态系统和生物资源,是我国重要的江河水源涵养地和重要的生态屏障。近年来,放牧家畜数量的增加使该地区传统草地畜牧业面临过度放牧、草地退化、季节性失衡等发展难题。为科学掌握黄河源区放牧家畜的情况,本文以黄河源区的玛多县为研究区,应用无人机对玛多县放牧家畜(牦牛、藏羊和马)的数量和空间分布开展航拍调查。根据牦牛、藏羊和马的无人机图像解译标志库进行目视解译,采用5种方法估算玛多县放牧家畜的数量,利用选择指数分析家畜空间位置与环境因子的关系,结果表明:①在冷季无人机航拍样带内,牦牛、藏羊和马的样带密度分别为4.12、7.34和0.06只/km^(2)。②玛多县有牦牛7.08万头,藏羊10.22万只,马0.12万匹,经验证,估算牦牛、藏羊和马数量的误差分别为-0.93%、2.27%和-13.23%。③家畜对环境因子的选择倾向于坡度小于12°,草地覆盖度高于0.6,距居民点小于1 km,距水源小于3 km,距公路大于3 km的区域。研究结果表明,无人机遥感技术在畜牧业方面有较大的应用潜力,为研究牧区放牧家畜的特征和草畜平衡情况提供新的思路。

西部地区生态状况变化及生态系统服务权衡与协同

西部大开发战略实施20年以来,一系列重大生态建设工程使得西部地区的生态状况和生态服务发生了重要变化,本文分析西部地区生态状况变化及其生态服务时空变化特征,并运用相关分析法研究其服务功能权衡协同关系。研究发现西部地区2000—2019年间:①聚落和湿地生态系统面积显著增加,草地有逐年下降趋势。②植被覆盖度呈波动上升趋势,存在年际差异且空间差异较大。③水源涵养服务有轻微下降趋势,下降区域主要分布在藏东南地区、三江源西部地区、喀斯特石漠化地区等;土壤保持服务波动中呈上升趋势,上升区域主要黄土高原地区、川滇西部地区、藏西北地区、藏东南地区等;防风固沙服务呈下降趋势,大幅下降区域主要位于内蒙古中西部地区、西藏和北疆部分地区。④生态系统供给与水源涵养、土壤保持主要为协同关系,与防风固沙主要为权衡关系且分布在农牧交错带地区。⑤生态工程区内生态系统服务协同程度大于非工程区。定量评估生态系统服务变化及其权衡协同关系有助于进行科学化生态管理,最大化生态效益。

六盘水市土壤侵蚀时空特征及影响因素分析

六盘水市是我国生态地位极其重要,水土流失又较为严重的城市。近些年,六盘水市实施了一系列生态工程,为了定量分析六盘水市土壤侵蚀状况及其影响因素,本文基于RUSLE模型,利用降雨数据、遥感影像数据、土地利用数据等,对贵州省六盘水市1990-2015年土壤侵蚀模数和土壤侵蚀量进行定量模拟,分析其时空动态变化,利用地理探测器定量分析影响因素,并进行空间相关性分析,结果表明:①六盘水市土壤侵蚀以微度和中度侵蚀为主。土壤侵蚀严重地区主要分布在北盘江流域与南盘江流域交界处以及喀斯特山地地区,煤矿开采使植被覆盖等抑制土壤侵蚀因子减少作用,使局部地区土壤侵蚀程度加剧。②1990-2010年平均土壤侵蚀模数整体为下降趋势,2010-2015年为上升趋势。其中2000年平均土壤侵蚀模数最大,2010年平均土壤侵蚀模数最小。该变化由降雨可蚀性因子和植被覆盖度因子综合影响所致。③植被覆盖度因子和多年平均降雨量因子是影响区域土壤侵蚀空间分布的重要因素。未利用土地、植被覆盖度小于0.3、坡度在25°以上和降雨量在1543~1593 mm之间的地区为高风险侵蚀区域。④植被覆盖度与土壤侵蚀在空间上全部呈负相关性,降雨因子与土壤侵蚀在空间上存在负相关性和正相关性。⑤土壤侵蚀改善区域大多分布在生态工程区域内,生态工程建设能够改善土壤侵蚀情况,不同生态工程保护侧重点不同导致土壤侵蚀改善程度不同。退耕还林还草工程对六盘水市土壤侵蚀的改善具有重要意义,六盘水市更宜退耕还林。

三北工程区植被恢复对土壤风蚀的影响及植被恢复潜力研究

三北地区是我国重要的生态屏障,分析2000—2019年三北防护林体系建设工程(简称:三北工程)区植被恢复时空变化状况,厘定人类活动与气候要素对植被恢复的贡献,探究植被恢复对土壤风蚀影响,评估植被恢复潜力空间,可为三北防护林体系建设工程未来规划管理和科学施策提供参考。本文在选取植被覆盖度和植被净初级生产力表征植被恢复状况基础上,利用地面数据,结合模型模拟,定量评估了2000—2019年三北防护林体系建设工程区植被恢复程度及其对土壤风蚀的影响,并对植被恢复潜力进行探究。研究结果表明:(1) 2000—2019年植被恢复程度高、较高的面积,占总面积的35.29%和13.16%,主要分布在黄土高原区及北部区域和风沙区与东北华北平原农区的部分地区。人类活动与气候因素对植被恢复贡献率为10.45%和89.55%;(2)土壤风蚀以轻度侵蚀和微度侵蚀为主,呈逐年下降趋势,剧烈侵蚀面积减少了66.45%,防风固沙服务得到进一步提升。植被恢复程度与土壤风蚀模数呈负相关关系,植被恢复程度较好有助于降低土壤风蚀模数;(3)三北工程区森林、草地和荒漠生态系统仍有8.16%的恢复潜力,内蒙古高原北部部分地区、哈顺戈壁北部和准噶尔盆地西北部及周边区域、黄土高原南部部分区域存在较大恢复潜力。

Soil erosion and its response to the changes of precipitation and vegetation cover on the Loess Plateau

Soil erosion is a major threat to our terrestrial ecosystems and an important global environmental problem. The Loess Plateau in China is one of the regions that suffered more severe soil erosion and undergoing climate warming and drying in the past decades. The vegetation restoration named Grain-to-Green Program has now been operating for more than 10 years. It is necessary to assess the variation of soil erosion and the response of precipita- tion and vegetation restoration to soil erosion on the Loess Plateau. In the study, the Revised Universal Soil Loss Equation （RUSLE） was applied to evaluate annual soil loss caused by water erosion. The results showed as follows. The soil erosion on the Loess Plateau between 2000 and 2010 averaged for 15.2 t hm-2 a 1 and was characterized as light for the value less than 25 t hm-2 a-1. The severe soil erosion higher than 25 t hm-2 a-~ was mainly distributed in the gully and hilly regions in the central, southwestern, and some scattered areas of earth-rocky mountainous areas on the Loess Plateau. The soil erosion on the Loess Plateau showed a deceasing trend in recent decade and reduced more at rates more than 1 t hm 2 a 1 in the areas suffering severe soil loss. Benefited from the improved vegetation cover and ecological construction, the soil erosion on the Loess Plateau was significantly declined, es- pecially in the east of Yulin, most parts of Yah＇an prefectures in Shaanxi Province, and the west of Luliang and Linfen prefectures in Shanxi Province in the hilly and gully regions. The variation of vegetation cover responding to soil erosion in these areas showed the relatively higher contribution than the precipitation. However, most areas in Qingyang and Dingxi pre- fectures in Gansu Province and Guyuan in Ningxia Hui Autonomous Region were predomi- nantly related to precipitation.

Effects of an ecological conservation and restoration project in the Three-River Source Region, China

The first-stage of an ecological conservation and restoration project in the Three-River Source Region（TRSR）, China, has been in progress for eight years. However, because the ecological effects of this project remain unknown, decision making for future project implementation is hindered. Thus, in this study, we developed an index system to evaluate the effects of the ecological restoration project, by integrating field observations, remote sensing, and process-based models. Effects were assessed using trend analyses of ecosystem structures and services. Results showed positive trends in the TRSR since the beginning of the project, but not yet a return to the optima of the 1970 s. Specifically, while continued degradation in grassland has been initially contained, results are still far from the desired objective, ‘grassland coverage increasing by an average of 20%–40%＇. In contrast, wetlands and water bodies have generally been restored, while the water conservation and water supply capacity of watersheds have increased. Indeed, the volume of water conservation achieved in the project meets the objective of a 1.32 billion m^3 increase. The effects of ecological restoration inside project regions was more significant than outside, and, in addition to climate change projects, we concluded that the implementation of ecological conservation and restoration projects has substantially contributed to vegetation restoration. Nevertheless, the degradation of grasslands has not been fundamentally reversed, and to date the project has not prevented increasing soil erosion. In sum, the effects and challenges of this first-stage project highlight the necessity of continuous and long-term ecosystem conservation efforts in this region.

Soil erosion rates and characteristics of typical alpine meadow using ~137Cs technique in Qinghai-Tibet Plateau

Alpine meadow is the predominant ecosystem in Qinghai-Tibet Plateau.The firm turf of alpine meadow formed by sub-surface anfractuous roots can be effective in conserving water and soil.Alpine meadow is a primary contributor to the Chinese Water Tower.For quantitative assess anti-erosion ability of alpine meadow,this paper selected three typical meadow slopes with>60% vegetation coverage to evaluate soil erosion rates using 137Cs.The results showed that(1)soil erosion intensity of typical alpine meadow was slight to light.Erosion rates were 464 t km–2 a–1 in Malong Village,415 t km–2 a–1 in Yeniugou Town and 875 t km–2 a–1 in Zhenqin Town respectively;(2)soil erosion rates were correlated negatively with vegetation coverage,and the relationship was clearer at the slope scale than plot scale;(3)the relationship between soil erosion and vegetation coverage showed that vegetation coverage was a predominant factor in retaining soil and water on slopes.With complete turf and high vegetation coverage, alpine meadow was of great significance for soil conservation and prevention of soil erosion.