Ecological Regionalization of Suitable Trees, Shrubs and Herbages for Vegetation Restoration in the Farming-Pastoral Zone of Northern China

To provide materials for the selection of plant species for vegetation restoration and reconstruction in the farming-pastoral zone in northern China, where the eco-environment has been already deteriorated by over-farming and over-grazing, the suitable trees, shrubs and herbages were examined, screened and identified under the guidance of four principles of taking precedence for ecological conservation, being beneficial to economic production, matching species (trees, shrubs and herbages) with the site, and giving consideration to the integrity of local administrative division. According to the key ecological factors that determine species growth and distribution in the zone, i.e., the lowest daily mean temperature in a year, annual accumulated temperature, and water regimes represented by the moist index, the ratio between annual rainfall and accumulated temperature (>0 degreesC), as well as the soil type influenced by climate, surface substances and landform, the farming-pastoral zone was regionalized into seven parts: ( I) Western Songliao Plain and Da Hinggan Mountain Region; (II) Upper Liaohe River Sandy Region; (III) Mid-Eastern Nei Mongol Plateau and Northwestern Heibei Mountain Region; (IV) Luliang, Taihang and Yanshan Mountain Region; ( V) Ordos Plateau Sandy Region; (VI) Northern Shaanxi to Eastern Gansu Loess Plateau Region; and (VII) Mid Gansu to Eastern Qinghai Plateau Loess Region. And the suitable trees, shrubs and herbages for each region were selected and tabularly introduced in detail.

Did Ecological Engineering Projects Have a Significant Effect on Large-scale Vegetation Restoration in Beijing-Tianjin Sand Source Region, China？ A Remote Sensing Approach

Aiming for the restoration of degraded ecosystems, many ecological engineering projects have been implemented around the world. This study investigates the ecological engineering project effectiveness on vegetation restoration in the Beijing-Tianjin Sand Source Region(BTSSR) from 2000 to 2010 based on the rain use efficiency(RUE) trend in relation to the land cover. More than half of the BTSSR experienced a vegetation productivity increase from 2000 to 2010, with the increasing intensity being sensitive to the indicators chosen. A clear tendency towards smaller increasing areas was shown when using the net primary productivity(NPP, 51.30%) instead of the accumulated normalized difference vegetation index(59.30%). The short-term variation in the precipitation and intra-seasonal precipitation distribution had a great impact on the remote sensing-based vegetation productivity. However, the residual trends method(RESTREND) effectively eliminated this correlation, while incorporating the variance and skewness of the precipitation distribution increased the models′ ability to explain the vegetation productivity variation. The RUE combined with land cover dynamics was valid for the effectiveness assessment of the ecological engineering projects on vegetation restoration. Particularly, the result based on growing season accumulated normalized difference vegetation index(ΣNDVI) residuals was the most effective, showing that 47.39% of the BTSSR experienced vegetation restoration from 2000 to 2010. The effectiveness of the ecological engineering projects differed for each subarea and was proportional to the strength of ecological engineering. The water erosion region dominated by woodland showed the best restoration, followed by the wind-water erosion crisscross regions, while the wind erosion regions dominated by grassland showed the worst effect. Seriously degraded regions still cover more area in the BTSSR than restored regions. Therefore, more future effort should be put in restoring degraded land.

Effects of fencing on vegetation and soil restoration in a degraded alkaline grassland in northeast China

In order to restore a degraded alkaline grassland, the local government implemented a large restoration project using fences in Changling county, Jilin province, China, in 2000. Grazing was excluded from the protected area, whereas the grazed area was continuously grazed at 8.5 dry sheep equivalent（DSE）/hm2. In the current research, soil and plant samples were taken from grazed and fenced areas to examine changes in vegetation and soil properties in 2005, 2006 and 2008. Results showed that vegetation characteristics and soil properties improved significantly in the fenced area compared with the grazed area. In the protected area the vegetation cover, height and above- and belowground biomass increased significantly. Soil pH, electrical conductivity and bulk density decreased significantly, but soil organic carbon and total nitrogen concentration increased greatly in the protected area. By comparing the vegetation and soil characteristics with pre-degraded grassland, we found that vegetation can recover 6 years after fencing, and soil pH can be restored 8 years after fencing. However, the restoration of soil organic carbon, total nitrogen and total phosphorus concentrations needed 16, 30 and 19 years, respectively. It is recommended that the stocking rate should be reduced to 1/3 of the current carrying capacity, or that a grazing regime of 1-year of grazing followed by a 2-year rest is adopted to sustain the current status of vegetation and soil resources. However, if N fertilizer is applied, the rest period could be shortened, depending on the rate of application.

Soil restoration research advances of artificial sand-binding vegetation ecosystem in the Tengger Desert, Northern China

Soil plays an important role in desert ecosystem, and is vital in constructing a steady desert ecosystem. The management and restoration of desertified land have been the focus of much discussion. The soil in Shapotou desert region has developed remarkably since artificial sand-binding vegetation established in 1946. The longer the period of dune stabilization, the greater the thickness of microbiotic crusts and subsoil. Meanwhile, proportion of silt and clay increased significantly, and soil bulk density declinced. The content of soil organic matter, N, P, and K similarly increased. Therefore, soil has developed from aeolian sand soil to Calcic-Orthic aridisols. This paper discusses the effects brought about by dust, microbiotic soil crust and soil microbes on soil-forming process. Then, we analyzed the relation between soil formation and sand-binding vegetation evolution, in order to provide a baseline for both research on desert ecosystem recovery and ecological environment governance in arid and semi-arid areas.

Different Responses of Vegetation to Frozen Ground Degradation in the Source Region of the Yellow River from 1980 to 2018

Frozen ground degradation under a warming climate profoundly influences the growth of alpine vegetation in the source region of the Qinghai-Tibet Plateau.This study investigated spatiotemporal variations in the frozen ground distribution,the active layer thickness(ALT)of permafrost(PF)soil and the soil freeze depth(SFD)in seasonally frozen soil from 1980 to 2018 using the temperature at the top of permafrost(TTOP)model and Stefan equation.We compared the effects of these variations on vegetation growth among different frozen ground types and vegetation types in the source region of the Yellow River(SRYR).The results showed that approximately half of the PF area(20.37%of the SRYR)was projected to degrade into seasonally frozen ground(SFG)during the past four decades;furthermore,the areal average ALT increased by 3.47 cm/yr,and the areal average SFD decreased by 0.93 cm/yr from 1980 to 2018.Accordingly,the growing season Normalized Difference Vegetation Index(NDVI)presented an increasing trend of 0.002/10 yr,and the increase rate and proportion of areas with NDVI increase were largest in the transition zone where PF degraded to SFG(the PF to SFG zone).A correlation analysis indicated that variations in ALT and SFD in the SRYR were significantly correlated with increases of NDVI in the growing season.However,a rapid decrease in SFD(<-1.4 cm/10 yr)could have reduced the soil moisture and,thus,decreased the NDVI.The NDVI for most vegetation types exhibited a significant positive correlation with ALT and a negative correlation with SFD.However,the steppe NDVI exhibited a significant negative correlation with the SFD in the PF to SFG zone but a positive correlation in the SFG zone,which was mainly limited by water condition because of different change rates of the SFD.

Response of Vegetation Cover Change to Drought at Different Time-scales in the Beijing-Tianjin Sandstorm Source Region,China

Dominated by an arid and semiarid continental climate,the Beijing-Tianjin Sandstorm Source Region(BTSSR)is a typical ecologically fragile region with frequently occurring droughts.To provide information for regional vegetation protection and drought prevention,we assessed the relations between vegetation cover change(measured by the Normalized Difference Vegetation Index,NDVI)and the Standardized Precipitation Evapotranspiration Index(SPEI)at different time-scales,in different growth stages,in different subregions and for different vegetation types based on the Pearson's correlation coefficient in the BTSSR from 2000 to 2017.Results showed that 88.19%of the vegetated areas experienced increased NDVI in the growing season;48.3%of the vegetated areas experi-enced significantly increased NDVI(P<0.05)and were mainly in the south of the BTSSR.During the growing season,a wetter climate contributed to the increased vegetation cover from 2000 to 2017,and NDVI anomalies were closely related to SPEI.The maximum correlation coefficient in the growing season(Rmax)was significantly positive(P<0.05)in 97.84%of the total vegetated areas.In the vegetated areas with significantly positive Rmax,pixels with short time-scales(1-3 mon)accounted for the largest proportion(33.9%).The sensitivity of vegetation to the impact of drought rose first and then decreased in the growing season,with a peak in July.Compared with two subregions in the south,subregions in the north of the BTSSR were more sensitive to the impacts of drought variations,especially in the Xilingol Plateau and Wuzhumuqin Basin.All four major vegetation types were sensitive to the effects of drought variations,especially grasslands.The time-scales of the most impacting droughts varied with growth stages,regions,and vegetation types.These results can help us understand the relations between vegetation and droughts,which are important for ecological restoration and drought prevention.

无人机倾斜摄影测量技术在林区植被恢复治理中的应用

林区植被破坏后,需要对破坏区域进行测量评估再实施恢复治理。林区由于树林的遮挡,存在通视困难。信号障碍等难题,使用传统的全站仪、GPS测量方法采集数据较为困难,本文提出,依靠无人机倾斜摄影测量模式获取空间数据,再通过三维建模,最后生成各类成果数据文件。项目实例应用证明本文的测量方法和模式有效,效果良好。

灵泉露天矿生态修复效果及驱动因素分析

煤矿开采通常会破坏土壤、植被,从而造成生态损伤。目前,高寒地区露天矿的生态修复工作尚处在起步阶段,针对高寒地区露天矿开展的生态修复效果及其驱动因素分析的研究较少。以灵泉露天矿为研究区,基于2009—2022年共11期Landsat影像,利用像元二分模型计算植被覆盖度,对矿区生态修复前后开展长时序植被覆盖动态监测,并进行生态修复效果和驱动因素分析。研究结果显示:矿区近十年来的植被覆盖度总体呈上升趋势,2017年大面积修复以后上升趋势尤为显著。气温和降水量是导致高寒地区露天矿植被覆盖度发生波动性变化的关键自然因素,其中,降水量是影响植被覆盖度持续上升的主要自然因素。植被覆盖度和土壤养分含量的变化相辅相成,植被覆盖度上升的同时会使土壤肥力提升,土壤肥力提升后又会促进植被覆盖度的上升。人工修复是高寒地区露天矿生态修复的主要方式,是高寒地区露天矿植被覆盖度上升的主要原因。研究结果表明,多年来的生态修复工作取得了显著效果,同时可为高寒地区露天矿的生态修复提供科学依据。

岷江干旱河谷土石混合边坡不同种植处理下乡土植被的生态效益

岷江干旱河谷生态环境脆弱,植被恢复困难,大规模的公路建设极易对当地生态环境造成破坏。筛选适宜的植被恢复措施对干旱地区道路边坡的乡土植被恢复重建和生态功能提升尤为重要。以岷江干旱河谷极端退化的土石混合的道路边坡为案例,选取乡土灌木和草本植物构建植物群落,进行裸地播种、播种后覆盖纤维毯和添加腐殖土后播种并地表覆盖纤维毯3种不同的种植处理,揭示了不同处理下群落结构、土壤改良以及水土保持效益的差异。发现,乡土灌草群落是干旱河谷适宜的道路边坡植被恢复模式,种植后第3年群落特征趋近于岷江干旱河谷区自然生态系统的多年生灌草植被。纤维毯覆盖+覆土处理在促进植物生长和群落构建,水土流失防治上效果最好,群落总盖度为74%,群落总生物量为506.35 g/m^(2);生长季内,与自然恢复相比小区径流量减少了87.8%,泥沙流失量降低了92.1%。土壤改良效应在3种处理之间差异不明显,但是与自然恢复样地相比,各处理均提升了边坡0-20 cm土层土壤养分。不同种植处理下植物群落结构差异是影响干旱河谷土石混合的道路边坡水土流失的关键因子。

抗冻型人造土冻融适应性及其在边坡植被修复中的应用

[目的]探究抗冻型人造土冻融适应性及其在高寒地区边坡植被修复中的实践效果,为高寒地区边坡植被修复工程应用提供理论依据和应用支撑。[方法]采用室内冻融循环试验剖判人造土在冻融循环60次期间的理化性质变化特征,结合主成分分析确定室外试验监测指标的选取,现场取样监测了近4 a人造土在西藏高寒地区岩质边坡的工程应用及其植被修复效果,并与当地天然土作对照分析。[结果]与天然土相比,抗冻型人造土的抗冻稳定性和肥力均有显著提升(p<0.05),具体表现在其冻融前后的相对动弹性模量、>0.25 mm水稳性大团聚体含量、平均重量直径(MWD)、团聚度及有机质、铵态氮、硝态氮、速效磷和速效钾含量显著提升,而质量损失率和结构破坏率显著降低(p<0.05)。主成分分析显示,室内试验指标中的相对动弹性模量、结构破坏率、pH值和有机质含量与主成分因子的相关性较高,因此在室外试验中监测这4个指标和植被修复情况。室外监测中发现抗冻型人造土4 a内在不同时间段上的结构破坏率均更低,相对动弹性模量和有机质含量更高;其边坡植被修复后的植被覆盖率、物种多样性、地上和地下生物量均更佳。[结论]抗冻型人造土在高寒地区应用时的植被修复效果更佳,特别是其抗冻耐久性、团聚体稳定性和肥力表现突出,均优于天然土,因此其更适宜于边坡植被修复应用。

三江源区草地水土保持与防风固沙功能临界植被覆盖度时空变化分析

三江源区是中国重要的生态安全屏障,其水土保持与防风固沙功能对中国及其周边地区生态安全具有重大意义。水土保持与防风固沙功能临界植被覆盖度是三江源草地生态保护与恢复的关键指标,但其变化尚不明确。本研究利用修正通用土壤流失方程(RUSLE)和修正通用土壤风蚀方程(RWEQ)模拟了1979—2018年三江源区草地水土保持与防风固沙功能临界植被覆盖度并分析了其时空变化。结果表明:(1)近40年来,三江源区草地水土保持功能临界植被覆盖度东南高、西北低,多年平均值为12.21%±1.42%,年增长率为0.30%(P<0.01)。(2)防风固沙功能临界植被覆盖度西北高、东南低,多年平均值为39.84%±11.94%,有不显著增长趋势。(3)水土保持及防风固沙功能临界植被覆盖度西北高、东南低,多年平均值为45.38%±10.04%,年增长率为0.32%(P<0.05),变化范围为11.73%~58.56%。三江源区西北部水土保持及防风固沙功能临界植被覆盖度大于50%,西南大部分区域不超过40%。(4)水土保持及防风固沙功能临界植被覆盖度在长江源区和黄河源区东北部呈下降趋势,其中黄河源东北部下降趋势显著(P<0.01),在黄河源区南部和澜沧江源区呈显著上升趋势(P<0.01)。本研究结果可为三江源生态环境保护以及高寒草地多目标管理提供科学依据与数据支撑。

黑龙滩水库消落带植被恢复模式对土壤水稳性团聚体组成及其稳定性的影响

[目的]为阐明水库消落带不同植被恢复模式对土壤水稳性团聚体组成及其稳定性的影响。[方法]以川中丘陵区黑龙滩水库消落带人工恢复与自然恢复植被下的土壤为研究对象,利用湿筛法测定分析土壤水稳性团聚体组成特征及其稳定性指标。[结果]消落带土壤>0.25 mm水稳性大团聚体含量与未淹水对照相比降低4.21%,其中,自然恢复植被下土壤水稳性大团聚体含量较对照下降12.27%,人工恢复植被下大团聚体含量较对照增加3.84%;不同植被恢复模式下土壤水稳性团聚体组成差异显著(p<0.05),人工恢复植被下土壤大团聚体含量(69.48%)显著高于自然恢复模式(43.20%);消落带土壤水稳性团聚体稳定性随水位高程增加而升高,团聚体稳定性指标>0.25 mm水稳性团聚体含量(R_(0.25))、平均重量直径(MWD)、几何平均直径(GMD)人工恢复模式下均大于自然恢复模式,团聚体分形维数(D)、土壤可蚀性因子(K)与团聚体破坏率(PAD)人工恢复模式小于自然恢复模式,表明人工恢复模式下土壤水稳性团聚体稳定性、土壤抗蚀性高于自然恢复模式。[结论]黑龙滩水库消落带在淹水后土壤团聚体稳定性下降,但人工恢复模式能有效改善土壤团粒结构,研究结果可为黑龙滩水库消落带土壤结构稳定性评价及植被恢复提供科学依据。

不同植被恢复类型下土壤碳含量对光伏组件遮阴的响应

【目的】探究云南石漠化脆弱区光伏场区不同植被恢复类型下,土壤微生物量碳(MBC)、可浸提有机碳(EOC)及总碳(TC)含量对光伏组件遮阴的响应特征,以期为石漠化脆弱区光伏电站退化土地生态恢复中的植被选型优化提供科学依据。【方法】2021年10月,在云南省昆明市东川光伏电站内,选取黄金菊(Euryops pectinatu)和红花檵木(Loropetalum chinense var.rubrum)2种人工建植植被样地,分别在每个样地的光伏板间(IP)、前檐(FP)、后檐(RP)、板下(UP)设置4个平行采样带,并以未受电站建设干扰的场外草地(以黄茅(Heteropogon contortus)为优势物种群落)样地作为对照(CK),测定2种植被恢复类型下光伏场区不同位置的光照强度以及表层(0~20 cm)的土壤温度、土壤碳(TC、MBC、EOC)含量以及土壤理化性质(pH、电导率、含水量),并分析光照强度、土壤温度、土壤碳含量以及土壤理化性质间的相关性。【结果】光伏场区不同位置的光照强度在07:00-19:00差异明显,且光照强度由大到小表现为对照>板间>前檐>后檐>板下,其中对照、后檐及板下位置的光照强度日变化均呈单峰变化,而板间和前檐位置的日变化均呈双峰变化趋势。场外的土壤温度明显高于光伏场区内,光伏场区不同位置的土壤温度差异较小。植被类型和光伏场区不同位置的光照异质性对土壤碳含量均有显著影响。在黄金菊样地,场区不同位置的土壤微生物量碳含量均较对照显著升高,其中前檐位置的土壤微生物量碳含量最高;在红花檵木样地,除了板间位置的土壤微生物量碳含量较对照显著降低外,其他位置均显著升高。2种植被恢复类型下不同位置土壤pH与对照无显著差异,土壤含水量和电导率均显著高于对照。相关性分析结果表明,光照强度与土壤微生物量碳含量和土壤含水量呈显著负相关,与可浸提有机碳含量、电导率、土壤温度呈显著正相关;土壤含水量与土壤可浸提有机碳和总碳含量均呈显著负相关(P<0.05)。【结论】在石漠化脆弱区的光伏场区,光伏组件遮阴与植被恢复均有利于提高土壤微生物量碳含量,但对可浸提有机碳和总碳含量的影响有一定差异,其中黄金菊样地的土壤可浸提有机碳和总碳含量明显高于对照。若短期内想达到较好的恢复效果,应优先选用黄金菊进行植被恢复。

植被恢复对塞罕坝地区土壤养分质量的影响(2002-2022年)

以位于塞罕坝机械林场和乌兰布统自治区级自然保护区交界处(116°32′~118°14′E、41°35′~42°40′N,海拔1 010.0~1 939.9 m)的森林-草原、干旱-半干旱地区交错带为研究区域,于2022年8月下旬在冀蒙界河两岸以2 km×2 km为基本网格单元进行机械布点,选取63个网格交点为取样点,按2022年植被恢复类型进行分类(华北落叶松(Larix principis-rupprechtii)人工林、樟子松(Pinus sylvestris var.mongolica)人工林、天然林(自然恢复的次生阔叶森林,以白桦(Betula platyphylla)为主)、放牧草地、封育草地);在每个取样点使用土钻法采集0~20 cm土层的土壤样品,每次取样以网格交点为中心,按东西走向间隔10 m设置3次重复,所取同样点3份土样风干过筛后等量混合均匀,检测土壤的全氮质量分数、全磷质量分数、全钾质量分数、速效磷质量分数、速效钾质量分数、碱解氮质量分数、有机碳质量分数;以土壤质量指数为评价指标,以7项土壤养分指标为影响土壤质量指数的因素,构建评价指标体系;采用主成分分析法、单因素方差分析法、多重比较法,分析2002年与2022年不同植被类型的土壤化学性质差异、近20 a植被恢复对塞罕坝地区土壤养分的影响、植被恢复过程中土壤养分的变化趋势。结果表明:植被恢复显著影响土壤养分储量,不同恢复方式对土壤养分的影响存在差异,但均对土壤养分总量有所消耗。以樟子松人工林消耗量最大,其土壤有机碳质量分数、全氮质量分数、全磷质量分数、全钾质量分数,与2002年森林相比分别下降了68.07%、60.87%、81.38%、25.87%,但不同植被恢复类型均能提升土壤养分有效性(土壤的碳质量分数∶氮质量分数(w(C)∶w(N))、碳质量分数∶磷质量分数(w(C)∶w(P))明显下降)。土壤质量指数分析表明,不同植被恢复后土壤质量比2002年均有所下降,华北落叶松人工林在维持土壤养分质量方面效果最佳,其土壤质量指数为0.54,与2002年森林土壤养分质量无显著差异。研究结果说明,在植被恢复过程中应考虑乡土树种的重要性,建议制定针有对性的养分管理措施以优化植被恢复效果。

基于植被覆盖度变化的山东泰山区域生态修复工程效果研究

采用最大值合成法、像元二分模型和趋势分析法,以NASA发布的2017—2022年MODIS NDVI 16d最大值合成数据为基础数据,通过植被覆盖度变化趋势对山东泰山区域生态修复工程整体效果进行研究。结果表明:2017—2022年泰山区域NDVI最大值和平均值总体呈波动上升趋势,最大值增长率为0.0055/a,平均值增长率为0.0049/a。山东省泰山区域Slope平均值为0.00478,生态修复工程绝大多数所处像元植被覆盖度变化率大于0,说明整个区域植被覆盖度有所改善,工程有明显效果。

西南石漠化区林下土壤养分特征及差异性

文章采用文献检索法收集20世纪90年代以来石漠化区植被修复和土壤研究相关论文,以全国二次土壤普查养分分级标准为基础,探讨林下土壤养分改良情况及土壤化学计量特征。结果表明:(1)中国西南石漠化区林下土壤总有机碳、全氮均值均高于全国二次土壤普查养分一等级,全磷处于二级范围,土壤养分改善效果明显,而全钾含量属于五级低钾区;(2)广西壮族自治区总有机碳和全氮均值为五省(区、市)第一,全磷和全钾位于二等级和四等级,土壤养分含量增加最明显;贵州省总有机碳、全氮高于一等级34%和37%,全磷值在二等级范围,全钾值位于第五等级,贵州省石漠化林下土壤养分改良明显;云南省总有机碳、全磷指标分别高于一等级9%、21%,全氮属于二等级,全钾属于五等级,土壤养分指标有不同程度提高;重庆市总有机碳高于一等级1.75%,全氮和全磷属于二等级,全钾为五省中最高且属于四级,土壤养分指标改良较其他三省慢;湖南省总有机碳指标为二等级,全氮、全磷、全钾值分别属于二等级、五等级、五等级,湖南省需加强石漠化治理的力度;(3)西南石漠化区土壤总有机碳和全氮指标呈正相关,植被生长亦受钾元素限制。其中,广西壮族自治区总有机碳、全氮和全磷存储快,土壤改良效益极其显著;贵州省土壤固碳能力高于全国平均值;云南省石漠化地区土壤钾元素偏低,影响植被生长;重庆市土壤中全钾含量高与总有机碳、全氮、全磷关系不大,氮元素成为限制植物生长的元素;湖南省植被生长需补充磷、钾元素。西南石漠化区植被生长应充分补充钾元素,除此之外,湖南、重庆需加强磷、氮元素的补充;云南、湖南、重庆应借鉴广西壮族自治区生态修复经验,加强石漠化生态治理并发挥效益。

干旱区受损植被生态恢复需水量——以新疆哈巴河县平原区为例

[目的]分析干旱区受损植被恢复过程中生态需水量,为生态恢复不同阶段所需水资源量及水资源优化配置提供科学依据。[方法]基于1990,2000,2010,2015,2020年Landsat系列影像,采用遥感技术,结合改进的彭曼公式法,对新疆哈巴河县平原区植被耗水量时空演变特征及生态恢复需水量进行了定量研究。[结果]①1990—2020年天然植被平均耗水量为7.55×10^(8)m^(3),以3.60×10^(7)m^(3)/5 a的速率减小,与之对应的是天然植被面积以17.36 km 2/a的速率减小,植被覆盖度从高植被覆盖度向中植被覆盖度转化,生态受损严重。②区域内植被耗水量时空分布均存在较大差异:空间上高值主要分布于哈巴河流域,别列则克河流域植被耗水量整体偏低;时间上年际变化以2000年植被耗水量为最高,年内植被耗水量则主要集中在生长中期。③绿洲区生态恢复需水量如下:维持现状(2020年)生态需水量为4.62×10^(8)m^(3),恢复到1990—2020年生态平均水平生态需水量为6.65×10^(8)m^(3),达到1990—2020年生态最佳水平(2000年)生态需水量为9.55×10^(8)m^(3)。[结论]在人为与自然二元作用下,灌区1990—2020年生态环境整体呈现退化趋势,生态耗水空间分配失衡,受损植被生态恢复需水量时空配置应根据耗水时空分布进行优化完善。

陕北黄土区不同林地土壤有机碳含量研究

为探究黄土高原植被恢复对深层土壤碳库的影响,选取退耕还林第一县陕北吴起县金佛坪流域5种植被恢复类型(山杏林(Armeniaca sibrica),油松林(Pinus tabulaeformis)、沙棘林(Hippophae rhamnoides)、刺槐林(Robinia pseudoacacia)、小叶杨林(Populus simonii))和以自然恢复为主的荒草地为研究对象,通过调查0~1000 cm土层土壤有机碳含量,并计算土壤有机碳储量,分析不同植被类型的土壤有机碳剖面分布和差异。结果表明:在总体上,土壤有机碳在0~60 cm出现快速下降,60~1000 cm出现不明显的波动变化,其中40~260 cm土层,小叶杨林地土壤有机碳含量明显最高。不同植被恢复都具有固碳效益,且不同植被土壤有机碳含量差异显著(P<0.05)。不同植被土壤有机碳储量:小叶杨(18年)(301.51 t·hm^(-2))>刺槐(19年)(249.86 t·hm^(-2))>沙棘(18年)(242.14 t·hm^(-2))>山杏(8年)(226.08 t·hm^(-2))>油松(5年)(182.91 t·hm^(-2))>荒草地(160.45 t·hm^(-2)),这可能是由于不同树龄和植被类型导致的结果。深层(100~1000 cm)土壤有机碳储量占0~1000 cm剖面有机碳储量的73%~84%。深层土壤有机碳含量颇丰,在今后碳汇评估中不容忽视。

黄土高塬沟壑区植被恢复方式对小流域土壤水分的影响

研究植被自然恢复和人工造林不同恢复方式下的土壤水分特性,对于揭示退耕还林(草)的长期水土保持生态效应具有重要的科学价值。本文基于黄土高塬沟壑区西峰水土保持科学试验站长达60多年的董庄沟(自然恢复草地)和杨家沟(人工造林)对比小流域,分析对比小流域土壤理化性质及土壤体积含水率的差异,阐明特定气候条件下植被自然恢复和人工造林2种不同植被恢复方式下流域的土壤持水能力。结果表明:(1)人工造林植被恢复方式下杨家沟小流域0~100 cm的土壤密度和土壤孔隙度分别是植被自然恢复的董庄沟的91.9%和1.1倍,土壤有机质质量分数和阳离子交换量分别高于董庄沟21.4%和22.6%,表层土壤理化性质未表现出差异性,不同植被恢复方式对持水能力的影响更多表现在深层土壤;(2)相同降雨条件下,董庄沟0~80 cm土层土壤体积含水率较降雨前平均增加8.85%,总量蓄水增加71.7 mm;杨家沟0~80 cm平均增加12.74%,总量蓄水增加102.1 mm;(3)董庄沟土壤体积含水率对降雨事件响应迅速,而杨家沟土壤水分随土层深度增加滞后现象明显。黄土高塬沟壑区西峰水土保持试验站经过60多年长期的植被恢复后,人工造林的杨家沟土壤持水能力要优于植被自然恢复的董庄沟。

西藏DG水电站工区边坡植被修复效果及生态因子分析

[目的]探究西藏DG水电站工区内边坡植被修复效果及主导生态因子,为提高工区植被修复成功率,治理水土流失,改善生态环境等提供理论依据和技术支撑。[方法]以工区内5种不同类型边坡(渣土堆积体、土质、土石混合、岩质、混凝土)为研究对象,选取土壤相对湿度、气温、坡度、坡向为生态因子,通过实地监测和取样分析,采用熵权法计算植被特征(物种多样性、物种丰富度、植被盖度)和土壤肥力(有机质、速效磷、速效氮、速效钾)权重分值,再由综合评价法计算综合得分,并结合极差分析甄选主导生态因子。[结果]西藏DG水电站工区内渣土堆积体边坡、土质边坡植被修复综合得分最高,均为10.0000,现场植被修复效果最好,而混凝土边坡植被修复综合得分仅为5.3690,现场植被修复效果较差;边坡类型不同,各生态因子对其植被修复影响的强弱不同,即土石混合边坡表现为:土壤相对湿度>坡度>气温>坡向,岩质边坡表现为:土壤相对湿度>气温>坡度>坡向,而土质边坡、混凝土边坡、渣土堆积体边坡均表现为:土壤相对湿度>坡向>坡度>气温,但主导生态因子却均为土壤相对湿度。[结论]影响西藏DG水电站工区内边坡植被修复主导生态因子为土壤相对湿度。不同类型边坡植被修复最优生态因子组合存在较大差异,其中土石混合边坡、岩质边坡、土质边坡、混凝土边坡和渣土堆积体边坡相对湿度和坡度均相同,差异主要体现在坡向和温度两方面。