Preparation and Water Retention Properties of Clay-based Sand-fixing and Grass-planting Materials

Targeting the problem of available water conservation in sand fixation, the sand-fixing and grass-planting materials were prepared with clay modified by emulsifying vegetable waxes and octylphenol polyoxyethylene ether （OP4）. The water retention property was studied in simulating desertification environmental climate and the materials were characterized by means of UV-Vis, SEM, FTIR, XRD and TGA measurements. The experimental result showed that the materials had excellent water retention properties, due to that vegetable waxes adhered evenly to clay particle surfaces, made the clay pores changing from hydrophilic to hydrophobic and so inhibited the water evaporation. Grass-planting experiment showed that, with reasonable mass ratio of clay, vegetable waxes and surfactant, the materials not only inhibited water evaporation but also maintained sound air permeability so shat the germination rate and survival rate of grass were significantly improved.

Sand-fixing characteristics of Carex brunnescens and its application with straw checkerboard technique in restoration of degraded alpine meadows

Carex brunnescens（Pers.）, a typical clonal species, is considered to be the only herb found to date that can develop on sand dunes in Maqu alpine region of northwestern China. However, the characteristics that C. brunnescens resists to harsh alpine environment have not been documented. In this study, we conducted a field investigation to determine the morphological, reproductive, and sand-fixing characteristics of C. brunnescens. Concomitantly, we transplanted the belowground rhizomes of C. brunnescens to sand dunes and compared the abilities to restore degraded alpine meadows among sand dunes that had no further treatment（SD＋N）, sand dunes that had straw checkerboard technique but no transplanted rhizomes of C. brunnescens（SD＋SCT）, and sand dunes that had both SCT and transplanted rhizomes of C. brunnescens（SD＋SCT＋P）. We found that belowground vertical rhizomes and horizontal rhizomes（including branching rhizomes and main rhizomes） of C. brunnescens were highly developed and that population reproduction was dominated by horizontal rhizomes. C. brunnescens exhibited a significant sand-fixation effect under following conditions： population density was 145–156 ramets/m^2, vegetation cover was 31.2%–39.3%, total length of belowground rhizomes was 11,223 cm/m^2, total length of belowground first-order roots was 9161–10,524 cm/m^2, fresh weight of aboveground part was 198.5–212.6 g/m^2, and fresh weight of belowground part was 578.8–612.4 g/m^2. It should be particularly noted that SD＋SCT＋P treatment（sand dunes that had both straw checkerboard technique and transplanted rhizomes of C. brunnescens） was the best and SD＋N（sand dunes that had no further treatment） was the worst in terms of following biotic indicators： total number of reproductive ramets, total number of belowground rhizomes, and fresh weight of aboveground and belowground parts of C. brunnescens, contents of soil organic carbon, available nitrogen, microbial biomass carbon, and microbial biomass nitrogen. It implies that applying SCT in sand dunes and transplanting belowground rhizomes to sand dunes with SCT could improve both soil fertility and growth of C. brunnescens. These results suggest that the SCT-promoted high reproductive abilities of belowground rhizomes of C. brunnescens can successfully facilitate the establishment of ramets and can thus be an effective strategy to restore degraded vegetation in Maqu alpine region of northwestern China.

Effects of forest cover types and environmental factors on soil respiration dynamics in a coastal sand dune of subtropical China

Trees on sand dunes are more sensitive to environmental changes because sandy soils have extremely low water holding capacity and nutrient availability. We investigated the dynamics of soil respiration(Rs) for secondary natural Litsea forest and plantations of casuarina,pine, acacia and eucalyptus. Results show that significant diurnal variations of Rsoccurred in autumn for the eucalyptus species and in summer for the pine species, with higher mean soil respiration at night. However, significant seasonal variations of Rswere found in all five forest stands. Rschanged exponentially with soil temperatures at the 10-cm depth; the models explain 43.3–77.0% of Rs variations. Positive relationships between seasonal Rsand soil moisture varied with stands. The correlations were significant only in the secondary forest, and the eucalyptus and pine plantations. The temperature sensitivity parameter(Q10 value) of Rsranged from 1.64 in casuarina plantation to 2.32 the in secondary forest; annual Rswas highest in the secondary forest and lowest in the pine plantation. The results indicate that soil temperatures and moisture are the primary environmental controls of soil respiration and mainly act through a direct influence on roots and microbial activity. Differences in root biomass, quality of litter,and soil properties(pH, total N, available P, and exchangeable Mg) were also significant factors.

Estimation of Sand Transportation Rate for Fixed and Semi-Fixed Dunes Using Meteorological Wind Data

Taibus County, Inner Mongolia, China, lies in a farming-pastoral ecotone, where severe wind erosion and various aeolian sand hazards are prevalent and fixed and semi-fixed sand dunes occur frequently. This study was conducted to investigate the relationships between sand transportation rate and wind speed for the fixed and semi-fixed sand dunes based on field measurements. The annual quantity of soil erosion by wind was estimated using meteorological wind data. The results indicated that the sand transportation rate in Taibus County in 2000 was 57.38 kg cm-1 year-1 for the semi-fixed dunes and 4.56 kg cm-1 year-1 for the fixed dunes. The total duration of erosive winds covered 12.5% of the time of the year, and spring posed the highest potential of sand transportation. Wind with low speed (≤ 17 m s-1) and high frequency plays a dominant role in sand transportation, while strong wind (≥ 17 m s-1) with low frequency significantly enhanced the sand transportation. Erosive wind speed, directions, and frequency were three crucial dynamic factors influencing sand hazards in the farming-pastoral ecotone. The dominant factors intensifying sand and dust storms in Taibus County might be related to the favorable wind condition in combination with the durable drought, which led to land desertification and vegetation degradation.

Plant water use strategies in the Shapotou artificial sand-fixed vegetation of the southeastern margin of the Tengger Desert, northwestern China

Stable oxygen and hydrogen isotopic compositions(δ^(18)O and δD) of plant xylem water and its potential water sources can provide new information for studying water sources, competitive interactions and water use patterns of plants. The contributions of different water sources to three plants, Hedysarum scoparium(HS), Caragana Korshinskii(CK) and Artemisia ordosica(AO), were investigated in the artificial sand-fixed vegetation of Shapotou, the southeastern margin of the Tengger Desert of northwestern China, based on meteorological data and δ^(18)O and δD values of precipitation, groundwater, soil water and xylem water of HS, CK and AO. Our results indicated that soil water infiltration through precipitation was the main water source of the artificial sand-fixed vegetation. Obvious differences in soil water content and in δ^(18)O of soil water and xylem water were found among different seasons. No relationship was found between the δ^(18)O in plant xylem water and in soil water in January. The same water use patterns were found in CK, HS and AO in May, suggesting they have the same water sources. The different water sources of CK, HS and AO in August indicate that water competition occurred. In addition, the main water sources of CK, HS and AO in August mainly come from shallow soil water, while they use relatively deep soil water in May. This phenomenon is related to the differences of soil water content throughout soil profile, precipitation, transpiration and water competition under different growth periods. The water use patterns of CK, HS and AO respond to soil water content throughout the soil profile and their competition balance for water uptake during different growth season. The results indicate that these sandfixed plants have developed into a relatively stable stage and they are able to regulate their water use behavior as a response to the environmental conditions, which reinforces the effectiveness of plantation of native shrubs without irrigation in degraded areas.

Sand mining disturbances and their effects on the diversity of arbuscular mycorrhizal fungi in a riparian forest of Iran

The major objective of this study was to evaluate the effects of sand mining disturbances on the diversity of arbuscular mycorrhizal fungi（AMF）. In addition, the proportional changes in the diversity of AMF to the distances from riverbanks were assessed. For this purpose, the riparian forest of the Maroon River, Iran was divided into three locations with a 200-meter wide zone in between. Thus, the locations studied were named Distance I（riverbank）, Distance II（intermediate）, and Distance III（farthest from riverbank）. In each of these distances, 10 Tamarix arceuthoides and Populus euphratica of each species were randomly selected. At the same time, soil and root samples were collected from the rhizosphere of the tree species studied. Results indicated that totally 13 AMF species were observed in T. arceuthoides and 19 AMF species were recorded in P. euphratica rhizosphere belonging to 6 genera and 6 families. In these AMF species, Glomus segmentatum, G. geosporum, G. rubiforme, G. nanolumen, G. spinuliferum, Claroideoglomus drummondii, Gigaspora gigantea and Acaulospora paulinae appeared only in P. euphratica rhizosphere, while G. multiforum and Claroideoglomus claroideum were observed only in T. arceuthoides rhizosphere. Moreover, Distance II had the least AMF species both in T. arceuthoides and in P. euphratica rhizospheres, and also the least spore density and root colonization rate. Our results are important in that they provide a list of resistant AMF species that could be used in the conservation of biodiversity.

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.

Efficacy of Pelletized Lime versus Limestone Sand for Forest Regeneration Enhancement in Pennsylvania, USA

The efficacy of limestone sand and pelletized lime for remediation of soil acidity was compared in order to determine if limestone sand was a more cost-effective alternative to pelletized lime. Between fall of 2002 and spring 2003, two forested sites in Pennsylvania were clear cut and fenced. Pelletized lime and limestone sand were applied to separate 400-m2 plots within the sites at rates of 2170 kg·ha-1 and 4335 kg·ha-1, respectively. Two additional 400-m2 plots were used as controls. A paired before-after control-impact study design was used to assess changes in soil, soil solution, vegetation and biomass after lime application. Soil samples were collected from the Oi, Oe + Oa, and A horizons before and after lime application. Woody and herbaceous vegetation was harvested from 1-m2 sub-plots before and after liming and bi-weekly soil solution samples were collected for six months following lime application. Analysis of variance procedures were used to compare changes in the treatment plots over time. Changes in soil chemistry following lime application were comparable on the limestone sand and pelletized lime plots. There was a significant increase in exchangeable Mg and Mg saturation in the Oe + Oa horizon on all of the lime treatment plots relative to controls, but a greater percentage of applied Ca and Mg was exchangeable in the O-horizon in pelletized lime plots nine months after liming. Plant biomass did not increase on the lime treatment plots relative to the control one year post treatment. The majority of applied Ca and Mg from pelletized lime and limestone sand remained in the litter layer, with little movement into the A-horizon after one growing season. These results indicated that the application of limestone sand at two times the rate of pelletized lime produced comparable changes in soil and soil solution chemistry at a fraction of the cost.

Spatio-temporal variation of soil moisture in a fixed dune at the southern edge of the Gurbantunggut Desert in Xinjiang, China

Soil moisture is critical for vegetation growth in deserts.However,detailed data regarding the soil moisture distribution in space and time in the Gurbantunggut Desert of China have not yet been reported.In this study,we conducted a series of in situ observation experiments in a fixed sand dune at the southern edge of the Gurbantunggut Desert from February 2014 to October 2016,to explore the spatio-temporal variation of soil moisture content,investigate the impact of Haloxylon ammodendron(C.A.Mey.)Bungeon soil moisture content in its root zone,and examine the factors influencing the soil moisture spatial pattern.One-way analysis of variance,least significant difference tests and correlation analysis were used to analyze the data.The results revealed that the soil moisture content exhibited annual periodicity and the temporal variation of soil moisture content throughout a year could be divided into three periods,namely,a moisturegaining period,a moisture-losing period and a moisture-stable period.According to the temporal and spatial variability,the 0–400 cm soil profile could be divided into two layers:an active layer with moderate variability and a stable layer with weak variability.The temporal variability was larger than the spatial variability in the active layer,and the mean profile soil moisture content at different slope positions displayed the trend of decreasing with increasing relative height and mainly followed the order of interdune area>west and east slopes>slope top.The mean profile soil moisture content in the root zone of dead H.ammodendron individuals was significantly higher than that in the root zones of adult and young individuals,while the soil moisture content in the root zone of adult individuals was slightly higher than that in the root zone of young individuals with no significant difference.The spatial pattern of soil moisture was attributable to the combined effects of snowfall,vegetation and soil texture,whereas the effects of rainfall and evaporation were not significant.The findings may offer a foundation for the management of sandy soil moisture and vegetation restoration in arid areas.

Carbon sequestration of plantation in Beijing-Tianjin sand source areas

The Beijing-Tianjin Sand Source Control Project(BTSSCP), a national ecological restoration project, was launched to construct an ecological protection system in the Beijing-Tianjin sand source areas to reduce dust hazards. The carbon sequestration dynamics can be used to assess the ecological effects of an ecological restoration project. Here, we conducted vegetation and soil study to assess the carbon sequestration in the plantations with 10 years old stands in Beijing-Tianjin sand source areas. The results at the site scales indicated that the average net increase of plantation ecosystem carbon stock was 33.8 Mg C ha^(-1), with an annual increase rate of 3.38 Mg C ha^(-1) yr^(-1). The average net increase of carbon varied among regions, vegetation types, and forest management activities. Soil bulk density in the top soil decreased slightly after 10-year implementation of the project. Coniferous forests and shrubs are suitable plant species for sand source areas.Natural restoration in the plantations is a practical and feasible and promising approach for enhancing ecosystem carbon sequestration potential.

Size and Shape of Sample Units in Native Forests and Plantations

The size and form of sampling units-SU have always been variables considered in planning and structuring forest inventories, being performed in forests or in plantations. The experimental work outlined to deal with the problem was conducted in an area of araucaria forest, in Sao Joao de Triunfo, PR, Brazil. The forms of sampling units circle, square and rectangular were evaluated, whose areas ranged from 200 m2 to 1000 m2. Time was recorded using a stopwatch and computed separately for locomotion and measurement. The power model was used to adjust the relations of the times of locomotion and measurement, as well as a hyperbolic one for the coefficient of variation, all taking as function of the SUs sizes. To achieve the analytical solution for the optimum size of the SU, it was necessary simulating the behavior of the three functions until the size of 10,000 m2. By taking the derivative of the combined function it was found the maximum point, which allowed optimizing the size of the SU in 600 m2 for the structured experimental conditions. This result proved the formulated hypothesis, performing even a critical analysis of the inclusion of other relevant variables, such as size of the area to be inventoried, number of SUs performed in one day of work, average distance between the SUs, average speeds for locomotion between SUs and for taking all respective measurements.

中国式现代化视域下习近平生态文明思想整体系统观及其方法论

党的十八大以来,在推进中国式现代化建设的伟大征程中,以习近平同志为核心的党中央坚持系统观念,基于对西方现代化道路的深刻反思和对自然界作为有机系统整体的精准认识,赓续与拓新马克思主义和中华优秀传统文化关于人与自然真实图景的系统辩证思想,形成和确立了丰富完备、逻辑严密的习近平生态文明思想整体系统观。秉持山水林田湖草沙是生命共同体的系统理念,这一整体系统观锚定生态文明建设和环境治理的目标任务,坚持推进中国式现代化生态文明建设与环境治理的系统层级观,坚持共同体构架的国内外合作治理的系统联动机制,对其内核“是什么”的问题作了精要而又深邃的回答。习近平生态文明思想层层追问中国式现代化生态文明建设之道,彰显了其整体系统思维在回答生态文明建设根本性问题上的强大方法论功能;以系统工程方式“全方位全地域全过程”推进生态文明建设与环境治理的全面系统展开,立体呈现了习近平生态文明思想整体系统观鲜明的方法论特质,为中国式现代化新征程上全面推进美丽中国建设提供了科学思想方法,开拓了中国式现代化恢宏壮丽的生态篇章。

山水林田湖草沙系统治理与水土保持高质量发展

[目的]中国水土流失治理已由“全面治理,重点治理”迈向“系统治理,攻坚克难”的新阶段。分析山水林田湖草沙系统治理的内涵、准则及其与水土保持的关系,旨在丰富新时代水土保持理论体系,引领水土保持高质量发展。[方法]在长期理论探索和实践验证的基础上,梳理山水林田湖草沙系统治理理念的发展过程,阐明其内涵、目标与实践准则。[结果]水土流失长期治理实践总结提升形成的以小流域为单元的综合治理技术路线是山水林田湖草沙生命共同体系统思想最朴素的实践体现。小流域综合治理的系统性主要体现为治理对象的系统协调,总体布局的系统统筹,治理措施的系统考量,治理成效的多效益兼顾,实施和管理的多部门协同和多主体参与的共治共享6个方面。水土保持高质量发展实践需要遵循的基于系统治理理念的具体举措包括:利用系统思维理解水土保持高质量发展的内涵和要求,精准诊断山水林田湖草沙系统短板及其控制性要素,构建山水林田湖草沙多层次全方位立体化防控体系,构筑完备的水土保持管理与技术保障体系。[结论]在新的历史时期,应该完整准确理解并全面贯彻落实山水林田湖草沙系统治理的理念,探索整体提升水土保持学术研究水平和治理效能的新路径、新模式、新机制。同时应结合区域或流域实际,对农田、水利、牧业、林业及生产建设活动进行全面综合系统的规划和治理,推动水土保持高质量发展。

基于生态韧性的山水林田湖草沙一体化保护修复框架

基于生态韧性内涵的山水林田湖草沙一体化保护修复是提升区域生态系统承载力和风险适应性的创新路径。本文阐述了生态韧性内涵与山水林田湖草沙生命共同体的特征,明确了一体化生态修复同生态韧性内涵关联逻辑,构建了山水林田湖草沙一体化保护修复的韧性作用机制和“问题识别-要素分析-策略制定”研究框架。以石家庄市为例,识别了其水土流失、湿地萎缩等生态问题,明确流域单元关键生态要素,并基于石家庄市生态系统地理空间格局以及面临的生态风险,提出调田节水、生境修复、林草保育等保护策略。以期为推进山水林田湖草沙系统修复工作以及增强生态系统应对干扰的抵抗力和适应力提供支撑。

基于沙漠治理智能小车的创新实验教学系统设计

针对教育部提出的提高高校学生的创新和实践能力,该实践教学系统依托学科竞赛,设计了沙漠治理自动化装置,将智能小车和砾石铺设装置组合在一起,通过控制系统控制智能小车的行驶轨迹,同时控制砾石铺设装置,将砾石按田字形规律铺设,达到减轻人工铺设的劳动量,提高铺设效率。该实践教学系统激发了学生的兴趣和潜能,培养了学生的科研能力和创新精神。

腾格里沙漠固沙植被区蚂蚁群落分布特征及其对土壤理化性质的影响

为了阐明固沙过程中蚂蚁群落结构分布特征及其对土壤性质的影响,在腾格里沙漠固沙植被区选取流动沙地以及5 a、8 a、34 a和57 a固沙植被区为研究样地,对不同样地蚂蚁群落的个体数、类群数以及蚁丘内外土壤理化性质进行测定,进而分析了不同样地蚂蚁群落分布特征及其与土壤因子间的关系。结果表明:(1)固沙植被区蚂蚁群落中的优势类群为掘穴蚁(Formica cunicularia),个体数占比为78.87%。(2)57 a固沙植被区蚂蚁密度显著低于8 a和34 a固沙植被区(P<0.05);5 a固沙植被区蚂蚁类群数显著低于其他植被区(P<0.05)。(3)57 a固沙植被区蚁丘中土壤含水量、土壤黏粒和土壤全钾显著高于非蚁丘,而土壤电导率和土壤粉粒显著低于非蚁丘(P<0.05)。8 a和57 a固沙植被区蚁丘中土壤pH显著高于非蚁丘,8 a固沙植被区蚁丘中土壤有机碳显著高于非蚁丘,8 a和34 a固沙植被区蚁丘中土壤全氮显著高于非蚁丘(P<0.05)。(4)蚂蚁群落组成与土壤粒径、电导率、pH、有机碳、全氮、全磷和有效磷含量的相关关系显著;偏RDA结果表明,蚂蚁类群数是影响固沙区土壤理化性质的主要限制因子。综合表明,腾格里沙漠不同固沙年限植被区蚂蚁群落组成差异较大,更丰富的蚂蚁群落有利于改善土壤质地,促进土壤理化性质向良好的方向发展,对实现荒漠生态系统恢复起到推进作用。

基于沙漠中铺设固沙草方格智能一体化装置

目前,在沙漠中铺设草方格是一种有效的治沙手段,因此设计一种沙漠中铺设固沙草方格智能一体化装置,从而提高沙漠治理的效率。本文主要介绍此固沙草方格建立的UG实体模型,并介绍了此装置的总体结构,具体分析了该装置的输送机构、步行机构、草席分离结构、插草机构以及传感器模块的使用,使用C语言设计了程序控制代码,论述了其工作原理。该铺设草方格智能一体化装置具有效率高,实用性强的特点。

古尔班通古特沙漠半固定沙丘上固沙灌木的空间结构特征研究

为明确固沙灌木种群空间结构变化的内外部特征和物种的生存机制,本研究以古尔班通古特沙漠半固定沙丘上的4种优势固沙灌木(白梭梭(Haloxylon persicum)、沙拐枣(Calligonum leucocladum)、蛇麻黄(Ephedra distachya)和油蒿(Artemisia ordosica))种群为研究对象,基于最近邻木空间结构参数(角尺度、混交度和大小比数)的一元和二元分布研究种群整体和不同生长阶段(幼株、营养株和生殖株)的种群的空间结构特征。结果表明:白梭梭和沙拐枣种群的株高和冠幅在不同生长阶段均高于蛇麻黄和油蒿种群;白梭梭、沙拐枣和油蒿种群呈随机分布,蛇麻黄种群的聚集程度相对较高;4个种群幼株表现出完全混交的状态;白梭梭和沙拐枣种群的生长状态优势度始终高于蛇麻黄和油蒿种群;4个种群的二元分布生长态势基本保持一致。研究结果对揭示固沙灌木的生长规律、生物多样性以及生态系统功能和过程的变化具有重要意义。

河西走廊阻沙固沙带典型荒漠植物叶功能性状

本研究以河西走廊阻沙固沙带典型荒漠植物梭梭(Haloxylon ammodendron)和白刺(Nitraria tangutorum)为研究对象,通过野外调查、样品采集、室内分析与统计相结合的方法,探讨荒漠植物对干旱环境的适应策略。因此,选取民勤绿洲阻沙固沙带和高台绿洲阻沙固沙带,分别自上风向的自然植被封育保护带和下风向的乔灌防护林带,空间结构特征较为一致的阻沙固沙带,设置3个10 m×10 m的梭梭样方和3个10 m×10 m的白刺样方。分析其叶片主要参数与环境因子的空间分布特征及其相关性,旨在为评价两种荒漠植物叶功能性状对干旱环境的适应策略提供数据支撑。典型荒漠植物均可通过调整叶功能性状以适应特定生境下的土壤和气候条件,结果表明:(1)叶干物质含量(LDMC)和比叶面积(SLA)差异显著(P<0.05),叶有机碳(LOC)、叶氮(LN)和叶磷含量(LP)在两种生境中均呈现出极显著差异(P<0.001)。(2)主成分分析表明,影响民勤植物叶功能性状的前3个指标因子为LN、C:N和C:P;影响高台植物叶功能性状的前3个指标因子为LP、C:N和N:P。(3)冗余分析表明,土壤含水量(SWC)、土壤有机碳含量(SOC)和空气干燥度(AD)是影响两种荒漠植物叶功能性状变化的主要限制环境因子。

灵武白芨滩柠条固沙林演替过程中林下草本植物多样性特征

林下植物物种组成对柠条固沙林的稳定性及生态环境的影响至关重要。本研究采用空间代替时间的方法,选取毛乌素沙地西南边缘不同种植年限(3、5、10、20、30、40、50、60和70 a)柠条固沙林为研究对象,对林下草本植物物种组成及多样性进行调查与分析。结果表明,1)各种植年限中,10 a时草本植物的物种数最少,40 a时草本植物的种类最多,截止到2020年8月为止,植物种数达到38种。2)随着林龄的增加,一年生草本植物的重要值逐渐降低,多年生草本植物的重要值逐渐升高。3)柠条固沙林下草本植物的丰富度指数、多样性指数、均匀度指数在3~10 a时变化一致,随林龄的增加而降低,10~40 a时丰富度随林龄的增加而增加,10~30 a时多样性和均匀度指数也随林龄的增加而增加,40~70 a时,各项指标趋于平稳。4)3~30 a林下草本植物群落相似性指数波动较大,到30 a之后林下草本植物群落相似系数指数变幅不大,逐渐趋于平稳。这表明在柠条群落建立30 a后,柠条林下草本群落已逐渐趋于稳定。种植柠条有助于荒漠生态系统的恢复,并在种植30 a时适当的抚育管理,将有利于林下草本多样性的维持。