In this study, the stable isotopic and hydrochemical composition of surface water is systematically investigated to reveal the potential sources, influencing factors and chemical weathering processes. Results show that the primary recharge source of surface water is local precipitation, and its isotopic composition influenced by both evaporation effects and altitude effects. Multiple factors can affect the major ion composition in surface water, including the atmospheric precipitation, anthropogenic input, and rock weathering. The average contribution rates from each endmember are 7.17

The water-level fluctuation zone of the lower Jinsha River Basin is a fragile ecosystem with limited water resources in the southwest of China. Soil water is critical for maintaining ecological balance and promoting the healthy development of animals and plants in this region. In this study, eight typical soil profiles were monitored for hydrochemistry in soil-soluble salt from upstream to downstream of the lower Jinsha River Basin. The results show that the soil water content was low and had a negative correlation coefficient with major ions in the soil-soluble phase. The soil-soluble salt is slightly alkaline, and Ca2+, Na+, SO42−, and HCO3− are important components for ions in a soluble phase. Major ions in soluble salt originate from various sources, including precipitation, anthropogenic input, silicate weathering, and carbonate weathering, and the contribution rates from each end member were 0.7%, 45.1%, 25.2%, and 29%, respectively. The ion composition in surface soil soluble salt is mainly influenced by precipitation and human activities, while the ions in the 0–50 cm soil layer originate from the precipitation input and water-rock interaction. In addition, rock weathering is a vital process for releasing ions into soil-soluble salt from 50 to 100 cm soil layer. Our findings provide important references for ion sources and the eco-hydrological process in limited water resources in the water-level fluctuation zone of the lower Jinsha River Basin.

适宜植物遴选是干热河谷库区消落带修复的关键.为筛选干热河谷库区消落带修复适宜耐淹抗旱植物,检验消落带修复有效性,本文以乌东德水电站库区己衣镇新民村消落带修复区为研究对象,结合定量与定性分析方法,观察并分析了不同物种、大小规格、种植海拔的植物在长期水淹后的生长和恢复情况.结果表明:(1)少量乡土植物可在消落带上段生长存活,乡土植物桑树、狗牙根、苍耳、苘麻可在整个消落带区域生长;(2)引进植物池杉、中山杉、乌桕、枫杨、小梾木、秋华柳可在干热河谷库区消落带区域生长;(3)大规格苗木在消落带生长更好,种子播种修复效果不佳;(4)修复区植物生长受干热气候、病虫害和种间竞争等因素影响.研究结果可为后续干热河谷库区消落带修复研究积累基础数据与实践经验.

干热河谷库区消落带生态修复关键技术难点在于当消落带植被受到长时间淹水与干旱交替双重胁迫时,如何遴选生态修复两栖植物.通过对乌东德库区消落带生态修复试验段淹没前植被调查、溪洛渡库区和三峡库区典型库岸消落带现存植物种群调查以及查阅三峡库区消落带植被自然演替和植被修复相关文献,结合乌东德水电站水位调度节律和库区干热河谷气候条件,对乌东德库区消落带植被自然演替趋势进行了分析.按照自然修复与人工修复相结合、乡土植物与外来植物相结合的消落带生态修复理念,遴选出乌东德库区消落带生态修复试验植物,提出了在试验段沿海拔高程的植物梯度配置模式:消落带中下部配置以狗牙根、香附子、扁穗牛鞭草等为主的多年生草本植物和以苘麻、狗尾草、马唐等为主的一年生草本植物;消落带上部配置以中山杉、水桦、桑树、秋华柳、银合欢等为主的乔、灌木以及草本植物.

消落带土壤水分是制约植物生长发育的关键因素,对库区消落带生态修复意义重大.本文系统分析了乌东德库区消落带修复试验区土壤含水量分布,探索了土壤水分空间变化和影响因素.结果表明:研究区5月水分含量低于5％,不同试验分区和高程区域土壤水分分布受到微地形、土壤特征、植被类型和植被覆盖度等影响.土壤水分随深度变化的主控因素包括地表蒸发和植物吸水,剖面深度大于50 cm的土壤水分是消落带植物潜在利用水源之一.本研究为干热河谷库区消落带土壤水分研究积累了基础资料,为消落带生态修复提供理论参考.

干旱沙漠区水资源是改善生态环境和促进动植物生存的关键.综合古尔班通古特沙漠研究成果,分别对该沙漠气候特征、水分分布和水分来源、水分循环和生态水文过程等方面进行归纳,指出现有研究存在的不足.在此基础上对古尔班通古特沙漠今后研究的方向和内容进行展望,指出将该沙漠不同水体纳入整体研究,以期丰富该沙漠生态水文机制和进一步探讨干旱区水文循环过程.

Ecological theory suggests that species with complementary architectural and physiological traits can optimize crown packing to improve resource efficiency and promote ecosystem productivity in forest communities. However, empirical evidence of this prediction is rare in species-rich natural forests, as little is known about how crown spatial complementarity regulates community species richness-productivity relationship (SRPR). In this study, we measured tree architectural traits (stem diameter, height, crown depth and width) for 11,337 trees, and quantified species richness, functional diversity, crown spatial complementarity, soil fertility and forest productivity for 44 quadrats (20 m × 20 m per quadrat) in the Badagongshan 25 ha forest plot, central China. We tested bivariate correlations between species richness, crown complementarity, functional diversity and forest productivity. We employed linear mixed effects models to predict crown complementarity and examined its relationship with functional diversity. Finally, we applied structural equation modeling to quantify the mediation effects of crown complementarity on SRPRs. Species richness promoted crown complementarity and forest productivity. Crown complementarity varied across quadrats, with increases driven primarily by changes in tree height. Crown complementarity was positively related to functional diversity and forest productivity. Species richness increased with soil total phosphorus, while functional diversity decreased with soil bulk density. Forest productivity increased with soil organic carbon and total nitrogen, but decreased with bulk density. Crown complementarity partially mediated the positive effect of species richness on forest productivity, and the mediation effect was mainly through functional diversity. Our results suggest that the crown complementarity index accurately reflects the niche complementarity through light utilization and carbon reallocation. Our study emphasizes that species richness can promote crown complementarity, leading to greater forest productivity, which provides greater insight into the mechanical understanding of the SRPRs.

植物是水库消落带重要组成部分,具有水土保持、污染过滤、物种多样性维持、景观美化等多种生态功能.为系统揭示干热河谷库区消落带植被演替趋势与规律,2019年7月至2020年7月对金沙江干热河谷乌东德库区消落带生态修复试验区水位上涨前的植被现状进行踏查与样方调查,分析了水淹前植物生长现状、特有的植物区系成分和植物种类.研究结果表明:(1)试验地共有维管束植物46科102属112种,其中禾本科、菊科和豆科植物种类最丰富,单科单属现象明显,一年生植物优势明显,具有典型的萨王纳植被特征;(2)群落类型包括车桑子+扭黄茅群落、银合欢+滇刺枣+扭黄茅群落和银合欢纯林群落,结构单一脆弱,人为干扰严重;(3)植物区系成分以热带为主,多为耐旱物种;(4)试验区经历水淹后,原有适应陆生环境的耐旱木本植物物种可能逐步减少,草本植物优势进一步增强,不同生活型植物占比发生改变,具体变化有待后续长期生态监测.研究结果可为后续干热河谷库区消落带生态修复研究与实践提供基础数据与参考依据.

干热河谷是我国西南地区一种特殊的自然景观,生态环境极端脆弱,加之消落带涉及面广,类型复杂,自我修复缓慢,增加了干热河谷生态治理的难度.为明确干热河谷生态治理的发展方向,介绍了干热河谷的基本情况,系统回顾了土壤类型、理化性质、水分分布和植被恢复技术、种类选择以及消落带治理方面的研究进展.目前干热河谷生态治理存在微观研究不够深入、缺乏长期动态监测、生态恢复效益评估指标单一化等不足,亟需应用先进技术手段,合理筛选优良的当地植物种类,建立生态环境长期动态监测与评估体系,加强生态系统自我修复功能,更科学有效地开展干热河谷生态治理.

金沙江干热河谷是我国重要的水利水电开发区.该区域水电站水库建成运行后将产生大面积库区消落带,严重威胁当地生态环境.本文从金沙江干热河谷水电站库区消落带植被现状、物种筛选、植物生理生态响应、植被恢复模式与技术、恢复生态效益评价等方面概括总结了该区域植被恢复研究进展与现状.针对金沙江干热河谷水电站库区消落带现有植被恢复研究实践不足的现状,提出该区域植被恢复宜根据地形地貌,结合生物技术和工程技术,综合利用多种生活型植物的植被恢复思路,指出金沙江干热河谷水电站库区消落带植被恢复未来研究重点,包括实践与示范、生态系统长期动态监测和管理政策研究等方向.

森林结构和地形是森林生态系统最明显的特点,也是影响林下幼苗存活和物种多样性的关键因子.该研究采用半球面摄影方法提取八大公山生长监测样地(共1.2 hm2)林冠结构参数,通过调查地表层木本植物幼苗的组成和多度,获取常见植物幼苗叶片功能性状,结合详细的地形信息,利用空间同步自回归模型探究林冠结构变量及地形因子对幼苗物种多样性及功能多样性的影响.结果表明:(1)八大公山亚热带山地常绿落叶阔叶林林冠结构复杂度较高,最大林冠高的平均值达到19.94 m,叶面积指数、平均叶倾角和林冠覆盖度分别为2.94、30.88°和0.87;(2)林冠结构变量和地形因子能够解释32.6％ ～48.4％的林下幼苗物种多样性指数变异和28.5％ ～70.2％的功能多样性变异,但地形因子对幼苗物种多样性的影响很小;(3)预测在亚热带常绿落叶阔叶林高海拔的山坡上,有较低的叶面积指数和平均叶倾角群落有较高的幼苗物种多样性;而在低海拔山脊上,较低的叶面积指数和平均叶倾角群落林下幼苗层有较高的功能多样性.此结果对科研人员和林业工作者开展野外森林更新情况评估和样方调查将有所帮助.

伴随着金沙江下游大型水电站的陆续建成,库区消落带将大规模形成并带来一系列生态环境问题.植被是消落带生态系统重要的组成部分,其演变对库岸稳定、水土保持、生物多样性和环境美化等方面具有深远的影响.通过系统回顾消落带植被恢复的研究进展,结合野外考察资料,从试验选址、适生物种选择、配置模式、种植与管护等方面总结消落带植被修复成果及经验,探讨了干热河谷消落带植被修复试验思路,明确了修复试验重点关注的方面,提出了抗旱耐淹物种选择的原则、条件和流程,并列出了适生植物物种推荐名录和植物梯级配置模式,以期为干热河谷消落带植被修复科研与实践提供参考.

以湖南八大公山25 hm2常绿落叶阔叶混交林动态监测样地中24个常见物种为研究对象,按照不同生长阶段(H1:5≤H＜20 cm、H2:20≤H＜40 cm、H3:40≤H＜80 cm、H4:80≤H＜ 130 cm、H5:H≥130 cm且DBH＜1 cm)获取了826株幼苗并测量了叶片和茎干功能性状,分析了不同生长阶段、冠层和叶片习性幼苗功能性状变异,以及不同功能性状对幼苗存活的影响.结果 表明:(1)幼苗功能性状在不同生长阶段差异显著,随着幼苗生长,比叶面积(SLA)、叶片碳氮比(C/N)呈现下降趋势,比茎密度(SSD)、叶柄长度(PL)、叶片氮磷比(N/P)和叶绿素含量(Chl)呈现升高趋势;(2) SLA在灌木层、亚乔木层和乔木层间无明显变化,叶片厚度(LT)、Chl和N/P在3个冠层间变化显著,SSD和PL均在灌木层和乔木层间无明显变化,C/N在灌木层和亚乔木层间无明显差异;(3)常绿树种幼苗具有较高的Chl和LT,落叶树种幼苗具有较高的SLA、叶片氮含量(LNC)、叶片磷含量(LPC)和PL;(4)个体大小对幼苗存活具有显著正效应,LPC促进落叶树种幼苗存活,抑制常绿树种幼苗存活.在植物生活史早期,不同功能群植物针对林下低光环境采取了不同生长适应策略,不同生长阶段幼苗也根据光环境的改变调整自身功能性状.另外,八大公山常绿落叶阔叶混交林中幼苗的生长主要受氮素限制,且这种限制作用随着幼苗生长逐渐减弱.

Spatial and temporal variation in species abundances and distributions of the seedling community, which plays a pivotal role in maintaining species diversity, can help predict future changes in forest communities. We monitored the dynamics of 12,830 seedlings within 405 1-m(2) seedling plots in the Badagongshan (BDGS) 25-ha forest dynamic plot over a 6-year period (2012-2017). We presented changes in the relative abundance for 15 dominant seedling species during the last six years, assessed temporal changes in species richness, species turnover, seedling density, species reordering (mean rank shift of the relative abundance; MRS) and community similarity within three topographically defined habitats (ridge, slope and valley), and explored the mechanisms underlying dynamics of seedling communities. Furthermore, we explored differences in species' ecological indicator values (EIVs) and functional groups for species gained and lost during the study period. Across three habitat types, there were enormous reordering of the 15 dominant seedling species; a few mast-seedling events were clearly identified. Both species richness and seedling density continually declined over the entire census year, except for an increase of species richness during 2012-2013. Species turnover fluctuated temporally in three habitat types; overall, species emigration rate was higher than species immigration rate in three habitats. Valleys with lower soil C:N ratio, light availability and VDCN (vertical distance above the channel network), but higher soil pH and TWI (topographic wetness index), had lower species richness and stem density, and higher species turnover and species reordering than slopes and ridges. At the community-wide scale, significant directional changes in species composition occurred on ridges and slopes. Newly colonizing species were typically more shade- tolerant, water- and temperature- demanding shrub species and grown on soil with low pH but high fertility. In the BDGS plot, species richness and seedling density fluctuated in the first two years and then decreased over time, which reflects that both habitat filtering and seed input regulated temporal dynamics of species composition, but the relative importance varied among studied years. In this subtropical forest, species composition showed obvious directional changes. Shrub species increased more than species of other strata in ridge and slope areas. It is worth noting that an increased dominance of species that are more water-demanding could increase the risk of mortality under global climate change (e.g. drought).

报道了湖北省神农架大九湖国家湿地公园内发现的湖北省维管植物分布的新记录类群,包括1个新记录属大爪草属(Spergula Linnaeus),含1个新记录种大爪草(Spergula arvensis Linnaeus);1种新记录的蕨类植物宪需耳蕨(Polystichumkungianum H.He&Li Bing Zhang);1个新记录变种,倒钩琉璃草[Cynoglossum wallichii var.glochidiatum (Wallich exBentham) Kazmi].这些新分布类群丰富了湖北省的植物多样性,为本地区的植物区系研究提供了新资料.

湖南八大公山国家级自然保护区位于武陵山系北缘,区内分布有大面积的常绿落叶阔叶混交林,物种多样性丰富,群落结构复杂.中国科学院武汉植物园按CTFS (Center for Tropical Forest Sciences)建设规范于2010-2011年在保护区内建设了一个25 ha的动态监测样地,为亚热带山地森林群落多样性长期动态监测提供了理想的平台.本文初步分析了八大公山25 ha样地的群落组成与空间结构.结果表明:群落内共有木本植物存活个体186,575株,隶属于53科114属232种;个体数超过1,000株的有38个物种(贡献87％的个体数),个体数最多的物种为黄丹木姜子(Litsea elongata);样地内稀有种(≤25株)种数占样地总物种数的44％,而个体数仅为样地总个体数的0.4％.样地内个体平均胸径为5.41 cm,其中68.4％的个体DBH ≤ 5 cm,DBH ≥ 20 cm的个体数(7,474株)仅约占总个体数的4％;个体胸径直方图呈倒“J”形,表明样地处于良好更新与正常生长状态.样地的种-面积关系图显示物种数随样地面积的增加而同步增加,其增长速度由迅速增长逐渐趋于稳定,取样面积10 ha时可以涵盖90％以上的物种;1ha小样地个体数平均为7,261.8±974.8 (SD),物种数平均为128.2±8.2 (SD),Shannon-Wiener指数平均为3.56±0.11 (SD),Pielou均匀度指数变异最小,平均为1.69±0.06 (SD);个体数与各多样性指数均无显著相关,表明在该样地中物种多样性的取样效应不明显,物种数量增加的原因可能来自于其他因素的控制.