Spatiotemporal characteristics of seed rain and soil seed bank of artificial Caragana korshinskii Kom. forest in the Tengger Desert, China

Vegetation restoration and reconstruction are effective approaches to desertification control and achieving social and economic sustainability in desert areas.However,the self-succession ability of native plants during the later periods of vegetation restoration remains unclear.Therefore,this study was conducted to bridge the knowledge gap by investigating the regeneration dynamics of artificial forest under natural conditions.The information of seed rain and soil seed bank was collected and quantified from an artificial Caragana korshinskii Kom.forest in the Tengger Desert,China.The germination tests were conducted in a laboratory setting.The analysis of species quantity and diversity in seed rain and soil seed bank was conducted to assess the impact of different durations of sand fixation(60,40,and 20 a)on the progress of vegetation restoration and ecological conditions in artificial C.korshinskii forest.The results showed that the top three dominant plant species in seed rain were Echinops gmelinii Turcz.,Eragrostis minor Host.,and Agropyron mongolicum Keng.,and the top three dominant plant species in soil seed bank were E.minor,Chloris virgata Sw.,and E.gmelinii.As restoration period increased,the density of seed rain and soil seed bank increased first and then decreased.While for species richness,as restoration period increased,it gradually increased in seed rain but decreased in soil seed bank.There was a positive correlation between seed rain density and soil seed bank density among all the three restoration periods.The species similarity between seed rain or soil seed bank and aboveground vegetation decreased with the extension of restoration period.The shape of the seeds,specifically those with external appendages such as spines and crown hair,clearly had an effect on their dispersal,then resulting in lower seed density in soil seed bank.In addition,precipitation was a crucial factor in promoting rapid germination,also resulting in lower seed density in soil seed bank.Our findings provide valuable insights for guiding future interventions during the later periods of artificial C.korshinskii forest,such as sowing and restoration efforts using unmanned aerial vehicles.

Distribution Characteristics of Soil Total Nitrogen in Low-efficiency Forest Land in the Northern Windy Desert Area of Jingbian County

[Objectives]The paper was to investigate the distribution characteristics of soil total nitrogen in low-efficiency forest land in the northern windy desert area of Jingbian County.[Methods]The distribution of soil total nitrogen in the 0-40 cm soil layer of 5 towns in the northern windy desert area of Jingbian County was studied through field sampling and laboratory detection.[Results]The average soil total nitrogen contents of Hongdunjie Town,Haizetan Town,Huanghaojie Town,Ningtiaoliang Town,Dongkeng Town and windy desert area in the 0-20 cm soil layer were 0.259,0.224,0.242,0.248,0.431 and 0.275 g/kg,respectively.The soil total nitrogen content in Dongkeng Town was higher than those in other towns,while there was little difference among other regions.The average total nitrogen contents in the 20-40 cm soil layer were 0.239,0.285,0.113,0.262,0.349 and 0.241 g/kg,respectively.The soil total nitrogen content in Huanghaojie Town was slightly lower than those in other towns,while that in Dongkeng town was higher.The variation coefficient of soil total nitrogen content in the survey area was greater than 30%,and there was great difference in spatial distribution.With the increase of soil depth,there was little change in soil total nitrogen content,namely the soil total nitrogen contents in 5 towns and windy desert area were not statistically different in the 0-40 cm soil layer.According to the nutrient grading standard of the second national soil survey,the soil total nitrogen content in the survey area was in the deficiency grade.[Conclusions]The research will provide a scientific guidance for the healthy and sustainable development of vegetation in arid regions.

Characteristics of the soil microbial population in forest land irrigated with saline water in the desert area

The study of soil microbial populations and diversity is an important way to understanding the soil energy process.In this study we analyzed the characteristics of soil microbial populations of the Tarim Desert Highway shelter-forest,by identifying microbial fatty acids and using methods of conventional cul-tivation.The results illustrated that the amount of soil microbial activity and the diversity of soil microbial fatty acid increased significantly with the plantation age of the shelter-forest;the soil microbial population was dominated by bacteria.The fatty acids of C14︰0,C15︰0,C16︰0,C17︰0,C18︰1ω9,C18︰0,C18︰2ω6 and C21︰0 were found to be dominant soil microbial fatty acids in the shelter-forest soil.Prin-cipal analysis and regression analysis showed that(1) concentrations of fatty acids of C14︰0,C16︰0 and C18︰0 could be used as indicators of total soil microbial population;(2) soil bacteria and actinomycetes populations were closely correlated with the amount of fatty acids of C15︰0 and C17︰0;and(3) soil fungi were closely correlated with the amount of fatty acids of C18︰1ω9 and C18︰2ω6.

How changes of groundwater level affect the desert riparian forest ecosystem in the Ejina Oasis,Northwest China

Groundwater is a key factor controlling the growth of vegetation in desert riparian systems. It is important to recognise how groundwater changes affect the riparian forest ecosystem. This information will not only help us to understand the ecological and hydrological process of the riparian forest but also provide support for ecological recovery of riparian forests and water-resources management of arid inland river basins. This study aims to estimate the suitability of the Water Vegetation Energy and Solute Modelling(WAVES) model to simulate the Ejina Desert riparian forest ecosystem changes,China, to assess effects of groundwater-depth change on the canopy leaf area index(LAI) and water budgets, and to ascertain the suitable groundwater depth for preserving the stability and structure of desert riparian forest. Results demonstrated that the WAVES model can simulate changes to ecological and hydrological processes. The annual mean water consumption of a Tamarix chinensis riparian forest was less than that of a Populus euphratica riparian forest, and the canopy LAI of the desert riparian forest should increase as groundwater depth decreases. Groundwater changes could significantly influence water budgets for T. chinensis and P. euphratica riparian forests and show the positive and negative effects on vegetation growth and water budgets of riparian forests. Maintaining the annual mean groundwater depth at around 1.7-2.7 m is critical for healthy riparian forest growth. This study highlights the importance of considering groundwater-change impacts on desert riparian vegetation and water-balance applications in ecological restoration and efficient water-resource management in the Heihe River Basin.

Nighttime sap flow and its driving forces for Populus euphratica in a desert riparian forest, Northwest China

Nighttime sap flow is a potentially important factor that affects whole-plant water balance and water-use efficiency （WUE）. Its functions include predawn disequilibrium between plant and soil water potentials as well as between the increments of oxygen supply and nutrient uptake. However, main factors that drive nighttime sap flow remain unclear, and researches related to the relationship between nighttime sap flow velocity and environmental factors are limited. Accordingly, we investigated the variations in the nighttime sap flow of Populus euphratica in a desert riparian forest of an extremely arid region, Northwest China. Results indicated that P. euphratica sap flow occurred throughout the night during the growing season because of the partial stomata opening. Nighttime sap flow for the P. euphratica forest accounted for 31%-47% of its daily sap flow during the growing season. The high value of nighttime sap flow could be the result of high stomatal conductance and could have significant implications for water budgets. Throughout the whole growing season, nighttime sap flow velocity of P. euphratica was positively correlated with the vapor pressure deficit （VPD）, air temperature and soil water content. We found that VPD and soil water content were the main driving factors for nighttime sap flow of P. euphratica.

Nutrient status of Populus euphratica growing in desert riparian forests of northwestern China

Seasonal and microhabitat variations of chemical constituents of foliar organic carbon （C）, total nitrogen （N）, total phosphorus （P）, and total potassium （K）, in Populus euphratica growing in desert riparian forests in northwestern China and their correlations were studied. Results show that ranges of C, N, P and K contents in the leaves ofP. euphratica were 39.08%-46.16%, 0.28%-2.81%, 0.05%-0.18% and 0.35%-2.03%, with means of 43.51%, 1.49%, 0.102% and 1.17%, respectively. The ratio of C/N, C/P and N/P changed from 16.26 to 146.61, from 258.08 to 908.67 and from 2.89 to 26.67; the mean was 37.24, 466.27 and 15.14, respectively. The mean N content was significantly lower than of deciduous trees in China, but the mean P content was nearly equivalent. The ratio of C/N was remarkably higher than of global land plants. The ratio of N/P indicated that growth ofP. euphratica was jointly limited by N and P nutrient deficiency. During the growth season, total trends of leaf C, N, P and K contents decreased. The max- imum appeared in May, and the minimum in September. Among microhabitats, C, N and K contents gradually increased from ri- parian lowland, flatland, sandpile, Gobi and dune, but C/N ratio was opposite, and P content was not apparent. Foliar C content was extremely, significantly and positively correlated with N and K contents, respectively. The relationships of N-K and P-K were both significantly positive.

A Comparative Study on Photosynthesis and Water Use Efficiency Between Clonal and Non_clonal Plant Species Along the Northeast China Transect (NECT)

Net photosynthesis ( P n ), transpiration ( E ), stomatal conductance ( g s) and water use efficiency (WUE) of more than 218 species belonging to two different reproductive functional types, i.e. clonal (115 species) and non_clonal species (103 species), along the 1 670 km Northeast China Transect (NECT) were analyzed. The results showed that P n and WUE appeared to be lower in the east and west ends of NECT, with peaks in the middle. Transpiration was found to be higher in the west end, where most temperate desert species were distributed. On the same site, most clonal species showed higher P n and related physiological variables than non_clonal species. For different growth forms over NECT, e.g. forest trees, shrubs and grasses, meadow steppe shrubs and grasses, typical steppe shrubs and grasses, the meadow steppe and typical steppe grasses, showed higher values of physiological variables than the forest or the desert species. But for the two reproductive plant functional types (PFTs), clonal species had higher physiological variables, with averages of 22%, 15%, 23% and 14% higher than the non_clonal ones for P n , E, g s, and WUE, respectively. Such differences indicated that clonal species might have advantages over non_clonal species in utilizing environmental resources such as light, CO 2, and especially water.

Temperature Regulation Effect of Desert Vegetation in Minqin Desert Area

[ Objective] The paper was to study the effects of desert vegetation on temperature regulation and stabilization in desert area. [ Method] The survey data of quadrats in five kinds of plant communities in Minqin desert area were preliminarily estimated. [Result] Desert vegetation had the ecological functions of regulating desert temperature and stabilizing sharp increase of temperature, especially the irreplaceable ecological function of slowing down sandstorm each spring in northwest China compared to physical sand-fixatian measures. The air humidity in forest region was relatively large, and the climate was more stable. The climate in desert area was dry, with intense changes in air temperature. Although the solar radiation utilization rate of desert vegetation per unit area in Minqin oasis fringe was 5.8% of that of 100% coverage vegetation, it had non-ignorable significance in regulating temperature of local desert. Regulating temperature was one of the ecological functions of desert vegetation. Previous studies only considered wind proof and sand-fixation functions of desert vegetation, but ignored its temperature regulation effect, and this was the ecological function of vegetation sand control different from physical sand-fixation measures such as sand barrier. [ Conclusion] It has important theoretical guiding significance and practical use value for prevention and control of desertification by studying ecological function of desert plants/vegetation.

Comparative Analysis of Wind break and Sand fixation Functions of Several Main Forage Plants in Minqin Desert Area

[Objective] The paper was to study wind-break and sand-fixation functions of forage plants in desert area. [Method]Based on the survey data of four major wind-break and sand-fixation plants( Haloxylon ammondendron,Artemisia arenaria,Nitraria tangutorum and Ephedra przewalskii) in Minqin desert area,the longitudinal section area and the sandpile volume of an individual plant and per unit area were calculated. The wind-break and sand-fixation functions of four major plant communities were comparatively analyzed. [Result] The wind-break functions of an individual plant( cluster) successively were N. tangutorum > H. ammondendron > A. arenaria and E. przewalskii; the sand-fixation functions of an individual plant( cluster) successively were N. tangutorum > E. przewalskii; the wind-break functions per unit area successively were A. arenaria > H. ammondendron > N. tangutorum > E. przewalskii; the sand-fixation functions per unit area were N. tangutorum > E. przewalskii; the wind-break and sand-fixation function per unit area were N. tangutorum > A. arenaria > H. ammondendron >E. przewalskii.[Conclusion]A. arenaria can be selected for only wind-break,and N. tangutorum can be chosen for only sand-fixation. If given consideration to both,N. tangutorum and A. arenaria must be selected.

Precipitation Controls on Carbon Sinks in an Artificial Green Space in the Taklimakan Desert

Control of desertification can not only ameliorate the natural environment of arid regions but also convert desertified land into significant terrestrial carbon sinks,thereby bolstering the carbon sequestration capacity of arid ecosystems.However,longstanding neglect of the potential carbon sink benefits of desertification management,and its relationship with environmental factors,has limited the exploration of carbon sequestration potential.Based on CO_(2) flux and environmental factors of artificial protective forest in the Taklamakan Desert from 2018 to 2019,we found that the carbon storage capacity of the desert ecosystem increased approximately 140-fold after the establishment of an artificial shelter forest in the desert,due to plant photosynthesis.Precipitation levels less than 2 mm had no impact on carbon exchange in the artificial shelter forest,whereas a precipitation level of approximately 4 mm stimulated a decrease in the vapor pressure deficit over a short period of about three days,promoting photosynthesis and enhancing the carbon absorption of the artificial shelter forest.Precipitation events greater than 8 mm stimulated soil respiration to release CO_(2) and promoted plant photosynthesis.In the dynamic equilibrium where precipitation stimulates both soil respiration and photosynthesis,there is a significant threshold value of soil moisture at 5 cm(0.12 m^(3) m^(-3)),which can serve as a good indicator of the strength of the stimulatory effect of precipitation on both.These results provide important data support for quantifying the contribution of artificial afforestation to carbon sequestration in arid areas,and provide guidance for the development and implementation of artificial forest management measures.

塔里木荒漠河岸林物种多样性沿地下水埋深梯度的分布格局

探讨荒漠河岸林土壤水分、物种多样性的空间变异性及其相互关系,可为干旱区天然林保护、可持续经营和生态恢复提供科学依据。以塔里木荒漠河岸林为研究对象,基于野外样带调查和采样测定,系统分析了地下水埋深(GWD)梯度下林地土壤水分与物种多样性的空间变异及其权衡关系。结果表明:随GWD增加和土壤水分减少,荒漠河岸林群落物种数减少、结构简化、群落发生退化,退化顺序为浅根系的中生草本植物和灌木,最后留存的是抗旱性较强的乔灌木或灌木;同时土壤水分和物种丰富度、物种多样性指数均呈显著的线性递减趋势,而物种均匀度指数降幅较小。GWD与土壤水分、物种多样性之间均呈极显著的相关(P<0.01),土壤水分与物种多样性的相对收益随GWD增加而逐渐降低,表明GWD是控制荒漠河岸林土壤水分和物种多样性空间变异的关键因素。荒漠河岸林土壤水分与物种多样性权衡关系的转折点为GWD 4.5m左右,转折点以下(GWD<4.5m)二者沿GWD以相同速率变化,呈协同关系;转折点以上(GWD>4.5m)土壤水分与物种多样性的权衡明显增大,土壤水分相对收益剧降,即维持当前相应的物种多样性以消耗土壤水分为代价,系统通过反馈调节使物种多样性降低。综上表明,维持塔里木荒漠河岸林物种多样性和生态系统功能的合理GWD在4.5m左右,这为塔里木河流域荒漠河岸林保育与生态输水工程实施提供科学依据。

Sap Flow of Populus euphratica in a Desert Riparian Forest in an Extreme Arid Region During the Growing Season

In the present study, the heat pulse technique was applied to investigate the stem sap flow of Populus euphratica in a desert riparian forest in an extreme arid region from April to October 2003 and from May to October 2004. The experimental sites were in Qidaoqiao （101 °10′ E, 41°59′ N） and Bayantaolai farm （101°14′ E, 42°01′ N） in Ejina county, in the low reaches of the Heihe River, China. The results indicated that the diurnal change in the velocity of sap flow showed minor fluctuations. At night, the rising of sap flow could be observed in the main tree species because of root pressure. During the growing season, the maximum average velocity was observed in July, followed by August, and the same velocity was observed in September and May; the minimum velocity was observed in October. The transpiration from June to August during the growing season accounted for approximately 70% of the annual total transpiration. The sap flow velocity of P. euphratica trees of different ages could be arranged in the order： 15 yr 〉 25 yr 〉 50 yr. Sap flow velocity was closely related to changes in micrometeorological factors, with average sap flow velocity showing a significant linear correlation with net radiation, air temperature and relative humidity.

Evapotranspiration and its main controlling mechanism over the desert riparian forests in the lower Tarim River Basin

Evapotranspiration(ET) and its controlling mechanism over the desert riparian forests in arid regions are the important scientific basis for the water resources managements of the lower reaches of the inland rivers of China. Nearly three years of continuous measurements of surface ET, soil water content at different depths and groundwater table over a typical Tamarix spp. stand and a typical Populus euphratica stand were conducted in the lower reach of the Tarim River. The ET seasonal trends in the growing season were controlled by plant phenology, and ET in non-growing season was weak. The diurnal variations of ET resulting from the comprehensive effects of all atmospheric factors were significantly related with reference ET. The spatial pattern of ET was determined by vegetation LAI, more vegetation coverage, more ET amount. Groundwater is the water source of surface ET, and the soil water in shallow layers hardly took part in the water exchange in the groundwatersoil-plant-air system. The temporal processes of ET over the Tamarix stand and the Populus stand were similar, but the water consumption of the well-grown Populus euphratica was higher than that of the well-grown Tamarix spp. Further analysis indicates that plant transpiration accounts for most of the surface ET, with soil evaporation weak and negligible; groundwater table is a crucial factor influencing ET over the desert riparian forests, groundwater influences the processes and amounts of ET by controlling the growth and spatial distribution of desert riparian forests; quantifying the water stress of desert riparian forests using groundwater table is more appropriate, rather than soil water content. Based on the understanding of ET and water movements in the groundwater-soil-plant-air system, a generalized framework expressing the water cycling and its key controlling mechanism in the lower reaches of the inland rivers of China is described, and a simple model to estimate water requirements of the desert riparian forests is presented.

Water use strategies of the desert riparian forest plant community in the lower reaches of Heihe River Basin, China

The object of this paper is the different plant communities in the Ejina desert riparian forest. Groundwater depth, soil moisture, plant water potential, relative leaf moisture content and water use efficiency was monitored, and the response of soil moisture and plant ecology to the groundwater depth and the water use efficiency of the different plant communities was analyzed. The results showed that：（1） Along with the groundwater depth increasing, predawn and midday water potential of the plants, with the exception of Reaumuria soongorica, did not decrease significantly, indicating that when the groundwater depth is less than 3 m, the plant communities in the range of 4 km from the river way did not suffer or slightly suffer from water stress;（2） The distribution of higher soil moisture content within 0–3 m soil layer is suitable with the plants’ root system, as indicated in the communities of coexisting overripe Populus euphratica or Taramrix chinensis, both of which can release excessive water into soil for shallow rooted shrubs or herbaceous plants when there is water shortage;（3） R. soongorica can absorb deep soil moisture through deep roots for their own survival;（4） The community consisting of Sophora alopecuroides, Karelinia caspica, T. chinensis, and overripe P. euphratica has the best species combination for restoring the damaged eco-environment in the lower reaches of Heihe River;（5） The order of plants’ relative leaf water contents is K. caspica ＆gt; S. alopecuroides ＆gt; young P. euphratica ＆gt; overripe P. euphratica ＆gt; mature P. euphratica = T. chinensis coexisting with other species ＆gt; single R. soongorica ＆gt; single T. chinensis and the order of WUE is single T. chinensis ＆gt; single R. soongorica ＆gt; T. chinensis living in symbiosis with other species ＆gt; S. alopecuroides = young P. euphratica ＆gt; mature P. euphratica ＆gt; overripe P. euphratica ＆gt; K. caspica. Therefore, with ample soil moisture, the plant community helps rapid growth of T. chinensis, young P. euphratica and R. soongorica plants of less moisture content. Despite this they do not have much water storage capability, but have strong drought resistance, and higher moisture contents of S. alopecuroides and K. caspica, thus leaving them with poor drought resistance. Overall, the desert riparian forest plant community in the lower reaches of Heihe River helps the species of higher WUE live on it.

Comprehensive eco-environmental effects of the shelter-forest ecological engineering along the Tarim Desert Highway

In this work, we report a comprehensive study about the eco-environmental effects of the shelter forest along the Tarim Desert Highway, including the effects on aeolian environment, soil, micro-climate, biodiversity, and groundwater. The results show that: (1) The movement of windblown sand near the ground surface was affected by the shelter forest. The wind speed and sediment transport rate in the shelter forest decreased by 64%―80% and 87.45%―99.02%, respectively. In addition, there were also significant changes in the sand flux structure, the sand grain size, and the deflation and deposition on the ground surface. (2) Compared to the natural mobile sand, the soil bulk density in the forest area decreased while the total salt content, the total porosity, and the water content increased. In addition, the soil fertility was significantly improved in the forest area, and showed the "first rapid, then slow" variation pattern. (3) The shelter forest showed positive effects on the micro-climate. Within the 6 m height above the ground, the air temperature in the shelter forest at different heights was lower than that in the mobile sand, while the air humidity was higher, while, the soil temperature was also lower in the shelter forest than mobile sand. (4) The number of soil microbial species increased significantly with the improvement of habitat in the shelterbelt. However, the population of different species was not distributed evenly across the surveyed area. (5) Currently, no significant effects of groundwater-pumping and forest-irrigation water have been found on the groundwater level and its salinity. The variation amplitude of both groundwater level and salinity was at the level of centimeters and 1g/L, respectively. No obvious variation trend has been observed.

洪水漫溢对林窗微环境时空差异的影响--以塔里木河中游荒漠河岸林为例

林窗是森林生态系统中普遍存在的干扰形式。探究洪水漫溢对林窗内部微环境时空异质性的影响,对揭示荒漠河岸林物种多样性变化及其更新特征具有重要意义。在塔里木河中游非洪水和洪水漫溢区各选取一个大小相似的林窗样地,并使用便携式气象监测仪对林窗内不同方位的空气温湿度进行监测,对比分析不同水淹条件下林窗内微环境的时空分布差异,为深入探索荒漠河岸林植被更新机制奠定基础。结果表明:(1)非洪水漫溢区和洪水漫溢区林窗内空气温度均呈现先上升后下降的变化趋势,空气湿度均呈现先下降后上升的变化趋势,且同一个样地中温度与湿度之间存在明显的负相关关系,而洪水漫溢改变了森林微环境,使林窗内湿度升高,温度下降。(2)非洪水漫溢区和洪水漫溢区林窗内不同方位温度分布差异较小,洪水漫溢对温度变化影响不大;两个样地林窗内湿度变化过程较为复杂,差异明显,洪水漫溢区湿度变化梯度更为密集。(3)非洪水漫溢区和洪水漫溢区林窗内温度差界限明显,西南方向温度差较小,中心位置温度差最大,洪水漫溢并未改变不同方位温度变化趋势;湿度差以中心偏北方向较大,其中非洪水漫溢区湿度差在西北方向较小,而洪水漫溢区湿度差最小值出现在西南方向。研究结果表示荒漠河岸林林窗微环境时空差异具有干旱区独特性,同时阐明了林窗微环境对洪水漫溢的响应,为深入研究林窗干扰对荒漠河岸林更新与演替提供了科学依据。

古尔班通古特沙漠流动沙丘土壤水分与地形—植被因子关系

[目的]确定沙漠沙丘土壤水分的分布规律,明确土壤水分与各个地形与植被因子间的关系,进而为沙漠地区的植被保护和重建提供科学合理的建议。[方法]以古尔班通古特沙漠流动沙丘为研究对象,在小尺度上研究了不同深度(表层0—40 cm,中层40—200 cm和深层200—300 cm)、不同微地貌(迎风坡、背风坡、丘顶和丘底)上土壤水分的分布特征(描述性统计);并采用广义线性、广义加性和随机森林模型研究了土壤水分与地形—植被因子间的关系。[结果](1)不同深度下迎风坡与丘底上的土壤水分高于背风坡与丘顶;表层土壤水分在背风坡(包括丘顶和丘底)与迎风坡上有显著性差异。(2)地形因子对土壤水分的影响大于植被因子;影响表层土壤水分的主要因子是坡度与坡向,影响中层和深层土壤水分的主要因子是灌木盖度。(3)随机森林模型的拟合效果显著高于广义线性和广义加性模型。[结论]地形因子对古尔班通古特沙漠流动沙丘不同微地貌上土壤水分的影响较植被因子大,坡度和坡向对表层土壤水分具有重要影响,灌木盖度对中层和深层土壤水分具有重要影响。

基于自然的山水林田湖草沙一体化保护和修复技术路径探索

研究目的:探索将基于自然的解决方案(NbS)融入山水林田湖草沙一体化保护和修复工程实施全过程的理论框架、技术路径,对其全过程技术体系和适应性管理进行研究,为科学推进工程实施提供理论基础和技术参考。研究方法:文献梳理、对比分析和归纳总结。研究结果:(1)山水工程实施的全过程应围绕NbS准则和指标要求,在调查评价、规划设计、工程实施和管理维护全过程融入NbS理念,以有效指导工程实施;(2)将NbS作为山水工程的理论指引,应针对特定生态问题和修复对象,识别关键修复要素并选择对应工程技术;(3)串联关键生态系统要素、贯通区域(流域)—保护修复单元—场地三个尺度是将NbS融入山水工程,推动全要素、多尺度、多层级治理的实现路径。研究结论:将NbS准则融入山水工程调查评价、规划设计、工程实施和管理维护全过程,是保证山水工程实施成效的关键,需尽快完善相关理论和实践研究、形成具体标准和范式,推动生态系统整体保护、系统修复和综合治理。

白垩系古沙漠露头遥感特征及其识别方法——以湘东南地区红层盆地为例

白垩系古沙漠风成砂岩是近年来湖南省新发现的一种沉积类型,该岩石不仅是特色的旅游资源,而且是全球关注的储能、储碳的重要目标储集层,因此对湖南省古沙漠的空间分布规律深入研究意义重大。本文引入遥感技术手段建立古沙漠露头遥感特征的识别及提取方法:以谷歌地球引擎(Google Earth Engine,GEE)为主要处理平台,以Sentinel-2A(哨兵二号)多光谱影像为主要数据源,从光谱、遥感指数和地形地貌三个方面分析古沙漠露头的遥感特征,采用随机森林算法进行古沙漠露头的遥感识别。区别于传统的陡直型丹霞地貌,古沙漠遥感影像色调均匀、连片分布,植被和山体阴影皆不发育,具有“顶圆,坡缓”的地貌特征。同时,深入分析古沙漠地貌的岩性特征,结合地质条件辅助约束,实现古沙漠露头的精准识别。通过上述方法,本文解译出湖南白垩系丹霞地貌区的多处古沙漠露头,并从识别结果中选择面积较大的衡阳盆地东缘(渡口地区)和茶永盆地东南缘(郴州市飞天山-高椅岭地区)地区的古沙漠风成砂岩进行了实地验证,效果理想。本文为研究古沙漠空间分布规律提供了高效的途径,是遥感技术在古沙漠地质领域的重要应用,旨在为国内地学界同行提供技术参考和借鉴。

腾格里沙漠流动沙丘上土壤水分与地形-植被因子的关系研究

土壤水分是沙漠植被的主要驱动因子,其分布受到地形、植被和气候之间相互作用的影响。以腾格里沙漠东南缘沙坡头地区流动沙丘上不同深度不同微地貌上的土壤水分作为研究对象,研究了土壤水分和地形-植被因子的分布特征。利用广义线性、广义加性和随机森林模型在小尺度上对因子关系之间进行分析建模。结果表明,(1)不同深度的4种微地貌中土壤水分呈现出丘底和迎风坡上的土壤水分显著高于背风坡,而背风坡又显著高于丘顶。(2)地形因子(主要指坡向)和植被因子对不同深度的土壤水分均具有重要的影响。其中,地形因子对表层和中层土壤水分的影响高于深层土壤水分,植被因子(主要指草本多度和生物量)对中层和深层土壤水分的影响高于地形因子。