用模糊聚类探讨福建三明格氏栲自然保护区植被类型的划分

初步统计三明格氏栲自然保护区有种子植物１４５科,４３４属,１０１０种（变种）。植物区系古老,地理成分以泛热和热带分成分较多,我们运用模糊聚类分析了保护区群落的划分,结果表明,划分的类型与用植物所在群落层中重要值来确定群落乔木层的优势种划分群系的方法基本相一致,计自然植被３个群系,格氏栲林,米储林,栲树林;人工植被５个群系：马尾松林,杉木林,建柏林,楠木林,毛竹林。     

中国南海海岸的红树林

红树林是热带海岸潮滩上一种特殊的植被类型和生物资源。我国南海海岸为我国红树林的重要分布区,包括桂、粤、台、闽南部海岸,但主要是广东省的海岸,尤为海南岛。群落的组成种类丰富,有21科、27属和38种,其中红树林的有9种,占世界红树科种数的54％。我国红树林根据其群落的各种特征,可以划分人海滩红树林和海岸半红树林两类,共包括15个群落类型,其组成种类、外貌结构与马来半岛及其邻近岛屿相似。因此,我国的红树林应属于世界红树林的东方群系。 木文还介绍我国南海海岸红树林的分布和演替,并根据红树林的特点提出保护和经营管理问题。     

武昌珞珈山植被及其演替研究Ⅰ.植被现状

在对武汉大学校园所在地武昌珞珈山全面踏勘的基础上,绘制了该区域的植被图,并将珞珈山植被划分为６植被型组１０植被型２０群系。通过对其中９个主要群落类型１２个样地的样方调查,得到了有关群落结构的基本资料。结果表明,武昌珞珈山的植被性质为人工次生植被,其主体是小叶栎＋樟林（面积１８．１８７ｈｍ２）、火炬松＋樟林（５．４７９ｈｍ２）、锐齿槲栎＋槲栎林（２．７１１ｈｍ２）和水松＋水杉＋池杉林（２．４１０ｈｍ２）,四者共占校园面积的２１．４５％。２０群系中９个群系的建群种可自然更新。     

雷州半岛红树林群落特征及其分布格局

以我国雷州半岛红树林为调查与研究对象, 采用样方调查方法对红树林区系组成、群落结构和分布特征开展调查分析。调查结果表明: 雷州半岛红树林的群落可分为24个类型, 其中白骨壤群落面积占比高达60.55%, 占有绝对优势; 雷州半岛红树林包括真红树植物8科13种, 占全国真红树植物物种的50%, 半红树植物8科10种, 占全国半红树植物物种的83.33%; Shannon—Wiener多样性指数为0.09—1.08, 部分研究区域之间数值差异较大; 从向陆林缘至向海林缘, 物种多样性沿潮间带的变化趋势比较一致, 为高潮间带>中潮间带>低潮间带; 白骨壤为雷州半岛重要的优势种, 在高、中和低潮间带均有分布, 聚集分布为高潮间带<中潮间带<低潮间带; 与2008年雷州半岛国家“908”专项红树林调查结果相比, 该地区所记录的红树物种由14种增加到了23种, 受2008年寒害所影响而枯死的红海榄又逐渐恢复; 附城镇1995年引进无瓣海桑, 与乡土种白骨壤、秋茄一起成为当地的优势种, 说明无瓣海桑的引进对于当地红树林群落恢复具有一定的促进作用。虽然雷州半岛物种组成较为丰富, 但是红树林群落结构仍然不够合理, 对残次天然纯林进行改造和人工多物种造林, 是日后雷州半岛红树林群落恢复和重建的重要方向; 同时也要加强乡土红树植物物种恢复, 维持雷州半岛红树林生态系统物种多样性与生态平衡。     

海南岛东寨港红树林群落甲烷通量研究

 采用静态箱法对海南东寨港4个站位的5个红树林群落的土壤甲烷通量进行了研究,结果表明林地土壤平均甲烷通量为0.81mg·m-2·d-1。利用聚乙烯袋密闭法测定了6种红树植物叶片的甲烷通量,发现红树植物叶片具有吸收大气甲烷的效应。通过海莲(Bruguiera sexangula)红树林的研究还表明,林地土壤甲烷通量的日变化与林内潮水淹浸状况有关。海莲林不同滩面土壤甲烷通量的差异与土壤含水量有关。土壤甲烷通量的季节差异因植被类型或土壤性质不同而表现为两种形式。     

粤东沿海红树林物种组成与群落特征

南海地区是全球红树林分布的中心区域之一。粤东沿海位于南海地区的北界,红树林物种组成和群落结构具有边缘性。利用卫星影像解译辅助技术,对筛选的23处红树林群落进行样地调查,记录了真红树植物12种,半红树植物6种,伴生植物7种。各群落平均高度为1.50—8.60 m,林相以灌丛、小乔木林为主。红树林群落Shannon-Wiener多样性指数为0.533—1.239,均匀度指数为0.662—0.957,天然林和人工林之间数值差异不显著。等级聚类分析将粤东沿海的红树林划分为演替早期人工林、演替早期天然林、演替中期天然林和演替后期天然林4个类别,各群落立地条件差异较大,沉积物总有机碳、盐度、总氮含量与群落分布状况的相关性较高。与1985年的报道相比,尽管该地区记录的红树林植物种类从20种增加至24种,但个别伴生植物消失以及半红树植物种群萎缩说明该地区红树林面临较大的环境压力。在物种多样性和均匀度均方面,粤东沿海红树林群落低于成熟红树林。过去数十年的围垦导致天然红树植物种群萎缩、生境破碎化是主要因素。基于该地区红树林群落的现状,未来人工林和残次天然林的优化改造是红树林恢复重建的重点,红树林恢复和保育的重点区域包括深圳湾的福田、范和港的蟹洲和韩江口的六合围。     

广东湛江红树林国家级自然保护区优势乔木群落的物种组成及结构特征

针对湛江红树林自然保护区的优势乔木群落, 根据优势种重要值大小对群落类型进行了划分, 进一步从立木、苗木和幼苗3 个层次对群落物种组成及结构特征进行了研究。结果显示: 4 科6 种红树植物组成11 个优势乔木群落。无瓣海桑群落分布最广, 平均胸径、高度和冠幅面积显著大于红海榄、秋茄、桐花树和白骨壤优势群落, 但无瓣海桑群落物种多度较低, 群落内无瓣海桑对秋茄有显著抑制作用; 白骨壤和秋茄优势乔木群落的多样性指数较高。红树林优势乔木群落林下层植被组成贫乏、结构简单, 以桐花树、秋茄和白骨壤为主; 林下苗木数量多于幼苗; 白骨壤幼苗占总量的67.1%。未来红树林恢复仍要重视本地红树物种, 建议加强白骨壤作为恢复物种的研究。     

中国的红树林

我国红树林主要分布在热带及亚热带沿海盐滩和河川出口的冲积盐性土上,包括24个科,47种,属于东方群系。从广西钦州湾开始经北海港,沿雷州半岛的海安分为两支,一支往南经海南岛的儋县新英港,向东经琼山县的东寨港和文昌县的清澜港,沿着东海岸至崖县的三亚港,又折向北到达东方县的八所港;另一支向东北经湛江的赤坎,阳江的海陵岛,台山的上下川岛,中山的三灶岛,新会的崖门,再沿海岸往北至福建的福鼎和台湾的新竹港。根据我国红树林的主要构成种类、外貌、生境,大致可分为3大群系和10个群落。(1) 矮灌木群系——这个群系多见于纬度稍高的海滩前缘,包括海榄雌群落和桐花树群落。这些群落在演替上处于前期阶段。(2) 高大稠密灌木群系——这个群系由于气温、年降雨量的差异和土壤性质的不同,组成这个群系的种类也有不同,不过都是以红树族的种类为建群种,它包括4个群落:红树群落、红海兰群落和角果木群落,这些群落在演替上属于中期阶段。(3) 乔木群系——这个群系主要分布在海南岛东北和东部海岸,所在地一般地势较高,前缘地带每日潮涨仍有海水浸淹。后缘地带只有每月大潮时才有海水到达,土壤比较固结,它包括木榄群落、海莲和尖瓣海莲群落、海桑群落及半红树林水椰群落。这些群落在演替上是处于后期阶段。组成我国红树林的种类大多数都具有较高的经济价值,如角果木是优质单宁的原料,有些种类经过发酵处理成为高营养的饲料和肥料。此外,沿海浮游生物的产量有红树林比无红树林的地带高达7倍,因此加强对红树林的经营和保护应采取积极态度和有效措施。     

中国的红树林

我国红树林主要分布在热带及亚热带沿海盐滩和河川出口的冲积盐性土上,包括24个科,47种,属于东方群系。从广西钦州湾开始经北海港,沿雷州半岛的海安分为两支,一支往南经海南岛的儋县新英港,向东经琼山县的东寨港和文昌县的清澜港,沿着东海岸至崖县的三亚港,又折向北到达东方县的八所港;另一支向东北经湛江的赤坎,阳江的海陵岛,台山的上下川岛,中山的三灶岛,新会的崖门,再沿海岸往北至福建的福鼎和台湾的新竹港。根据我国红树林的主要构成种类、外貌、生境,大致可分为3大群系和10个群落。(1) 矮灌木群系——这个群系多见于纬度稍高的海滩前缘,包括海榄雌群落和桐花树群落。这些群落在演替上处于前期阶段。(2) 高大稠密灌木群系——这个群系由于气温、年降雨量的差异和土壤性质的不同,组成这个群系的种类也有不同,不过都是以红树族的种类为建群种,它包括4个群落:红树群落、红海兰群落和角果木群落,这些群落在演替上属于中期阶段。(3) 乔木群系——这个群系主要分布在海南岛东北和东部海岸,所在地一般地势较高,前缘地带每日潮涨仍有海水浸淹。后缘地带只有每月大潮时才有海水到达,土壤比较固结,它包括木榄群落、海莲和尖瓣海莲群落、海桑群落及半红树林水椰群落。这些群落在演替上是处于后期阶段。组成我国红树林的种类大多数都具有较高的经济价值,如角果木是优质单宁的原料,有些种类经过发酵处理成为高营养的饲料和肥料。此外,沿海浮游生物的产量有红树林比无红树林的地带高达7倍,因此加强对红树林的经营和保护应采取积极态度和有效措施。     

基于快速普查方法的深圳植被优势种特征研究

植被普查是了解城市地表植被群落特征最常见的方法,也是进一步进行城市生态学、植物学等研究的方法基础。基于植被调查的不同目的、不同尺度、不同地貌,调查人员所选择的方法也各有差异。此次调查旨在对深圳陆域尺度的优势种特征进行研究,利用高分辨率遥感卫星图片与地面实地调查相结合的方法对深圳陆域植被开展了快速普查,结果显示：（1）深圳陆域共有优势植物182科、858属、1443种,其中被子植物占主要地位,占优势植物总种数的94.66%;（2）从优势种子植物科的地理分布来看,深圳陆域优势种子植物科归属于14个分布区,植物地理成分较为复杂,热带区系属性非常明显;（3）划分出非邻近的纹理异质性群丛斑块83834个,归为741类群系,12个植被型,南亚热带常绿阔叶林、南亚热带草丛、南亚热带灌丛占绝对优势;（4）经统计,郊区群系类型较城区更为丰富,郊区608类群系,城区569类群系,其中,共有群系437类,城-郊各自优势植物科、属、种数量差异不明显;（5）对比《中国外来入侵植物名录》和相关学者的学术论文,筛选出深圳外来入侵植物62科、200属、258种,主要集中在豆科、菊科、禾本科等科。根据本次植被快速普查过程和结果给出城市植被管理和改善植被普查方法的建议,旨为今后的城市政策制定和规划实施提供科学依据。另外为了验证此次调查方法的科学性和调查结果的正确性,将本文结果与采用传统长周期方法的两支高校调查队伍的调研结果进行了比对,本次结果包含高校队伍调查结果优势种数量的88.5%,体现了本方法在优势植物物种普查中的有效性。     

Functionality of restored mangroves: A review

Widespread mangrove degradation coupled with the increasing awareness of the importance of these coastal forests have spurred many attempts to restore mangroves but without concomitant assessment of recovery (or otherwise) at the ecosystem level in many areas. This paper reviews literature on the recovery of restored mangrove ecosystems using relevant functional indicators. While stand structure in mangrove stands is dependent on age, site conditions and silvicultural management, published data indicates that stem densities are higher in restored mangroves than comparable natural stands; the converse is true for basal area. Biomass increment rates have been found to be higher in younger stands than older stands (e.g. 12 t ha⁻¹ year⁻¹ for a 12 years plantation compared to 5.1 t ha⁻¹ year⁻¹ for a 80-year-old plantation). Disparities in patterns of tree species recruitment into the restored stands have been observed with some stands having linear recruitment rates with time (hence enhancing stand complexity), while some older stands completely lacked the understorey. Biodiversity assessments suggest that some fauna species are more responsive to mangrove degradation (e.g. herbivorous crabs and mollusks in general), and thus mangrove restoration encourages the return of such species, in some cases to levels equivalent to those in comparable natural stands. The paper finally recommends various mangrove restoration pathways in a functional framework dependent on site conditions and emphasizes community involvement and ecosystem level monitoring as integral components of restoration projects.     

Temporal patterns in a fish assemblage of a semiarid mangrove zone in Madagascar

Gillnet sampling was conducted for a year in a tropical mangrove creek (SW Madagascar), characterized by a limited freshwater influence, a high turbidity and a tidal range up to 3 m. Sixty species of juvenile fishes were caught, 44 species being of commercial interest. Catches were dominated by Gerreidae (27% of total abundance), Teraponidae (16%), Carangidae (13%) and Sparidae (12%). The temporary resident fishes in the mangrove zone represented 50% of the species and 97% of the total abundance, the other species being rare (less than five individuals). The species richness, abundance and biomass per netting were low in the middle of the cool season (July-August). Monthly changes in the fish assemblage were particularly complex, with three species groups displaying a clear seasonal pattern, some species succeeding one another in a rather unstructured way, and three species abundant throughout the year. There was no clear structuring effect of temperature, salinity and turbidity on the fish assemblage. However, tidal, lunar and diel effects on the composition of the fish assemblage were evident. The species overlap between the Sarodrano mangrove fauna and the adjacent coral reef fauna is particularly weak with six species in common and shows that the mangrove plays only a very limited nursery role for coral reef species.     

Environmental and anthropogenic factors associated with coastal wetland differentiation in La Mancha,Veracruz, Mexico

At least 10% of the wetlands in Mexico are situated in the State of Veracruz on the central Gulf coast. The region has been intensively used for agriculture by humans for the last thousand years and today pastureland for cattle ranching is the dominant element of the landscape. We present a study of the wetland vegetation in a series of representative and internationally significant freshwater wetlands near the coastal lagoon La Mancha in Veracruz State. We obtained eleven wetland types formed by three wetland communities dominated by trees (mangrove or swamps), eight dominated by herbaceous species which we classified as marsh, five of which were native emergent marsh, one was a non-native emergent marsh and two were floating-leaved marsh. The highest diversity values were found in the Annona swamp, followed by the Sagittaria marsh and the Rhizophora–Laguncularia–Avicennia mangrove. CCA ordination showed that water level, disturbance and species number were the major factors explaining variation along axis 1, and on axis 2 conductivity, salinity, and bulk density. Wetland size was a major factor in both axes. We examined the interplay of intrinsic and extrinsic factors that give rise to the nature and diversity of wetland types that characterize the important wetland landscapes in this part of Mexico, being disturbance by human activities an important factor that favors the appearance of diverse species combinations.     

Trophic analysis and trophodynamic functioning of mangrove fish fauna of New Caledonia]

Fish communities from geomorphologically different mangrove forests showed distinct trophic structures. A mangrove area located near fringing reefs (Bouraké) was dominated by large invertebrate (> 2 mm) feeders (40.7% of total wet weight of the fish fauna) and herbivores (26.7%) whilst an estuarine mangrove (Ouenghi) was characterized by detritus feeders (28.2%), piscivorous (18.2%) and large invertebrate feeders (17.9%). In spite of these differences in trophic structure, similar food webs occurred in both areas, whereas the intensity of fluxes between trophic compartments was different. Resident species were usually at the base of the trophic structure. This component of the fish fauna used available sources of energy, such as microalgae in Bouraké or detritus and phytoplankton in Ouenghi. In contrast, transient species were high level predators, mainly piscivorous and large invertebrate feeders. These species actively contributed to net exports of energy from mangrove areas to nearby coastal habitats. Food webs and energy fluxes associated with trophic migration of fishes were particularly important in non-estuarine mangrove forests because of hydrologic conditions (salinity and turbidity) which were more suitable to the invasion of numerous marine foraging species (carangids, lutjanids, sphyraenids).     

Global biodiversity and biogeography of mangrove crabs: Temperature,the key driver of latitudinal gradients of species richness

Mangroves are ideal habitat for a variety of marine species especially brachyuran crabs as the dominant macrofauna. However, the global distribution, endemicity, and latitudinal gradients of species richness in mangrove crabs remains poorly understood. Here, we assessed whether species richness of mangrove crabs decreases towards the higher latitudes and tested the importance of environmental factors such as Sea Surface Temperature (SST) in creating the latitudinal gradients in species richness of mangrove crabs. A total of 8262 distribution records of 481 species belonging to six families of mangrove crabs including Camptandriidae, Dotillidae, Macrophthalmidae, Ocypodidae, Sesarmidae, and Oziidae were extracted from open-access databases or collected by the authors, quality controlled, cleaned, and analyzed. Species richness was plotted against 5° latitudinal bands in relation to environmental factors. The R software and ArcGIS 10.6.1 were used to analyze the species latitudinal range and richness as well as to map the distribution of mangrove forest, endemic species, species geographical distribution records, and biogeographic regions. The Indo-West Pacific showed the highest species richness of mangrove crabs where more than 65% of species were found in the Indian Ocean and along the western Pacific Ocean. Our results showed that there are 11 significantly different biogeographic regions of mangrove crabs. The highest endemicity rate was observed in the NW Pacific Ocean (29%). Latitudinal patterns of species richness in Macrophthalmidae, Ocypodidae, and Sesarmidae showed an increasing trend from the poles toward the intermediate latitudes including one dip near the equator. However, latitudinal gradients in Camptandriidae, Dotillidae, and Oziidae were unimodal increasing from the higher latitudes towards the equator. Species richness per 5° latitudinal bands significantly increased following mean SST mean (°C), calcite, euphotic depth (m), and mangrove area (km²) across all latitudes, and tide average within each hemisphere. Species richness significantly decreased with dissolved O₂ (ml l⁻¹) and nitrate (μmol l⁻¹) over all latitudes and in the southern hemisphere. The climax of global latitudinal species richness for some mangrove was observed along latitudes 20° N and 15°–25° S, not at the equator. This can suggest that temperature is probably the key driver of latitudinal gradients of mangrove crabs’ species richness. Species richness and mangrove area were also highly correlated.     

Occurrence and Diversity of Yeasts in the Mangrove Ecosystems in Fujian, Guangdong and Hainan Provinces of China

Mangrove wetland is a unique ecosystem and has rich bioresources. In this article, the roots, stems, branches, leaves, barks, fruits, and flowers from 12 species of the mangrove plants and six species of the accompanying mangrove plants, seawater and sediments in mangrove ecosystems in China were used as sources for isolation of yeasts. A total of 269 yeasts strains were obtained from the samples. The results of routine identification and phylogenetic analysis showed that they belonged to 22 genera and 45 species. Of all the 269 strains, Candida spp. was predominant with the proportion of 44.61%, followed by Kluyveromyces spp. (8.55%), Pichia spp. (7.44%), Kodamaea ohmeri (5.58%), Issatchenkia spp. (4.83%) and Debaryomyces hansenii (4.46%). We also found that strains N02-2.3 and ST3-1Y3 belonged to the undescribed species of Pichia sp. and Trichosporon sp. respectively while strain HN-12 was not related to any known yeast strains. This means that different yeast strains of Candida spp. especially C. tropicalis were widely distributed in the mangrove ecosystems and may have an important role in the mangrove ecosystems. The results also showed that some of them may have potential applications.     

Physiological adaptability of three mangrove species to salt stress

The impact of salinity on three arboreal mangrove plants, Sonneratia apetala (Sa), S. caseolaris (Sc) and Rhizophora stylosa (Rs), was studied. The three mangrove species were treated with different salinity levels over a three-month period. The response and adaptation of these three mangrove species to salinity were shown to be different. Net photosynthesis rate, stomata conductance and transpiration rate of leaves decreased and soluble sugar content in leaves increased, with salt concentration in all three mangrove species. The malondial dehyde (MDA) content in stems and leaves of Sa and Sc somewhat decreased when the salinity was lower than 10, but rapidly increased with increasing salt concentration. The MDA content in stems and leaves of Rs increased only when salinity was greater than 40. No changes were observed in the MDA content of roots in the three mangrove species. The adaptabilities of Sa and Sc to salt tolerance were limited. The more salt tolerant the mangrove Rs, the more likely the free oxygen radicals were eliminated through the increase in activity of superoxide dismutase (SOD). Results of this experiment identified salinity levels best suited for the growth and metabolism of the species, which provides information necessary for maintaining mangrove forestation along the South China coast.     

Physiological adaptability of three mangrove species to salt stress

The impact of salinity on three arboreal mangrove plants, Sonneratia apetala (Sa), S. caseolaris (Sc) and Rhizophora stylosa (Rs), was studied. The three mangrove species were treated with different salinity levels over a three-month period. The response and adaptation of these three mangrove species to salinity were shown to be different. Net photosynthesis rate, stomata conductance and transpiration rate of leaves decreased and soluble sugar content in leaves increased, with salt concentration in all three mangrove species. The malondial dehyde (MDA) content in stems and leaves of Sa and Sc somewhat decreased when the salinity was lower than 10, but rapidly increased with increasing salt concentration. The MDA content in stems and leaves of Rs increased only when salinity was greater than 40. No changes were observed in the MDA content of roots in the three mangrove species. The adaptabilities of Sa and Sc to salt tolerance were limited. The more salt tolerant the mangrove Rs, the more likely the free oxygen radicals were eliminated through the increase in activity of superoxide dismutase (SOD). Results of this experiment identified salinity levels best suited for the growth and metabolism of the species, which provides information necessary for maintaining mangrove forestation along the South China coast.     

三种红树植物对盐胁迫的生理适应

无瓣海桑（Sa）、海桑（Sc）、红海榄（Rs）都属于乔木红树植物。这3种红树植物对盐度的敏感程度存在着差异,因此对不同标准的盐度的适应性也大不相同。通过对这3种红树植物用不同的盐度的水3个月的处理,发现Sa和Sc叶片的净光合作用速率、气孔导度、蒸腾速率都随着盐度的增加而降低。Sa,Sc,Rs叶片中的可溶性总糖含量随着盐度的升高整体上有上升趋势。Sa和Sc茎、叶中丙二醛（MDA）含量在低盐度时（〈10）略有降低,随着盐度升高,MDA含量急速升高,而Rs茎、叶中MDA只是在盐度超过40时才会有明显增长,3种红树植物根部的MDA含量变化都不明显。Rs可以依靠超氧化物歧化酶（SOD）来消除活性氧自由基,而红树植物Sa和Sc的耐盐性稍差,SOD对膜的保护能力不强。根据实验结果,可以得出对3种红树植物对盐度的适应范围,这将为指导中国南海海岸线上的红树造林计划提供依据。     

红树林区软体动物生态位的三种分析方法

利用广东湛江红树林保护区定量取样获取的软体动物密度数据,根据Shannon-Wiener和Pj．anka公式,分别选用潮带和季节（方法1）、红树植物群落和季节（方法2）、红树植物群落和潮带（方法3）3种不同环境因子组合确定环境资源位点数,从而计算研究区软体动物生态位宽度和物种间重叠值。结果表明,3种分析方法计算结果有差别,采用方法1、方法2和方法3计算的物种生态位宽度分别为0～1．96、0～2．16、0～1．64;生态位重叠指数为0～0．1的种对,方法1、方法2和方法3分别占25．1％、32．8％和21．6％,生态位重叠指数为0．1～0．5的种对,分别占31．6％、36．2％和22．3％,生态位重叠指数〉0．5的种对分别占43．396、3196和56．1％。可见,方法3计算出的生态位重叠指数比其它2种方法的大。物种聚类和排序也验证了3种分析方法的计算结果有差别。将计算结果与实际定量取样比较,表明以红树植物群落和季节为准确定环境资源位点数的分析方法与实际相符,适合红树林区软体动物的生态位研究。