广西大石围天坑群不同植物群落的特征

大石围天坑群孕育了极为丰富的植物多样性资源。为进一步了解大石围天坑群植物群落特征, 该文在天坑不同位置(坑口、坑腰、坑底)以及坑外共布设25个样地, 采用样方法进行调查, 共鉴定出269种维管植物, 隶属于89科176属, 群落物种组成数量较多的科主要有樟科、蔷薇科、荨麻科等。群落成层现象明显, 各层优势种分布较为均匀, 其中乔木层优势种主要有香木莲(Manglietia aromatica)、南酸枣(Choerospondias axillaris)、掌叶木(Handeliodendron bodinieri)等, 灌木层优势种有异叶梁王茶(Metapanax davidii)、滇鼠刺(Itea yunnanensis)等, 草本层以楼梯草属(Elatostema)占优势。群落季相明显, 以常绿、落叶阔叶混交林为主, 底部有常绿阔叶林分布, 坑口边缘小面积分布有落叶阔叶林; 群落生活型谱: 高位芽植物为55.76%, 地上芽植物为29.74%, 地面芽植物为6.69%, 隐芽植物为5.21%, 一年生植物为2.60%。该文分析了天坑植物群落类型、组成、结构等特征。     

Plant community composition, not diversity, regulates soil respiration in grasslands

Soil respiration is responsible for recycling considerable quantities of carbon from terrestrial ecosystems to the atmosphere. There is a growing body of evidence that suggests that the richness of plants in a community can have significant impacts on ecosystem functioning, but the specific influences of plant species richness (SR), plant functional-type richness and plant community composition on soil respiration rates are unknown. Here we use 10-year-old model plant communities, comprising mature plants transplanted into natural non-sterile soil, to determine how the diversity and composition of plant communities influence soil respiration rates. Our analysis revealed that soil respiration was driven by plant community composition and that there was no significant effect of biodiversity at the three levels tested (SR, functional group and species per functional group). Above-ground plant biomass and root density were included in the analysis as covariates and found to have no effect on soil respiration. This finding is important, because it suggests that loss of particular species will have the greatest impact on soil respiration, rather than changes in biodiversity per se.     

漳江口红树植物群落周转对大型底栖动物群落结构的影响

在城市化的背景下,探明不同大型底栖动物群落对植物群落变化的响应,对红树林生态系统的健康评价和退化生态系统的修复具有重要意义。以福建漳江口国家级红树林自然保护区为研究对象,揭示红树植物群落周转对不同大型底栖动物群落结构（蟹类和软体动物）的影响,并分析其与环境参数的关联性。结果表明：在1.6 km的地理尺度上,漳江口红树林湿地的环境变化较大,表现出7.19个环境梯度。在此地理尺度的环境梯度上,红树植物群落由5种红树植物组成,其平均周转率为76%;软体动物群落由12种软体动物以模块化和非随机的方式聚集,其平均周转率为83%,并随红树植物群落周转出现显著非线性增加,盐度和老鼠簕（Acanthus ilicifolius）周转是其主要影响因素;蟹类群落则由20种蟹类以更高的模块化和非随机的方式分散,平均周转率为89%,并随红树植物群落周转而呈线性增加,主要受pH和白骨壤（Avicennia marina）周转的影响。研究揭示了大型底栖动物与植物群落和环境之间的关系,为城市化背景下红树林生态系统的保护和恢复提供基础资料。     

深圳杨梅坑山地植物群落演替动态

以深圳市杨梅坑山地两个植物群落为调查对象,分析其物种组成、物种多样性特征、重要值的变化,探讨不同阶段植物群落的演替动态规律。结果表明,两个植物群落经过7年演替后,植物群落的丰富度有所增加,且种类组成出现明显差异,两个植物群落在不同时期所呈现的自然景观不一样。群落科、属、种的数量差异明显。原鸭脚木-九节-铁线蕨群落2013年共有26科36属39种,2018年共有19科29属30种,2019年共有32科51属61种;原绒毛润楠-瓜馥木-团羽铁线蕨群落2013年共有25科30属33种,2018年共有24科33属33种,2019年共有42科67属83种。两个植物群落乔木层、灌木层、草本层三个层次的物种多样性指数和Pielou均匀度指数几乎都呈先下降再上升的趋势。演替系列中,乔木层、灌木层和草本层的物种组成均表现出耐荫种替代非耐荫种的趋势,且植物群落的层次由简单趋向复杂。     

植物群落和土壤理化性质对碧塔海湿地土壤细菌群落的影响

土壤微生物是湿地生态系统中土壤-植物系统生源要素迁移转化的引擎.探究湿地生态系统地上植物群落、土壤理化性质和空间结构与土壤细菌间的相互关系是维护湿地生态系统健康和稳定的关键.本研究运用双向指示种分析法(TWINSPAN)对碧塔海湿地采集的35个样方中的植物群落进行分类,并采用高通量测序技术对样方的表层土壤细菌进行测序,...     

Tree size frequency distributions, plant density, age and community disturbance

We show that explicit mathematical and biological relationships exist among the scaling exponents and the allometric constants (α and β, respectively) of log–log linear tree‐community size frequency distributions, plant density N_T, and minimum, maximum and average stem diameters (D_min, D_max, and , respectively). As individuals grow in size and D_max increases, N_T is predicted to decrease as reflected by a decrease in the numerical value of α and an increase in the value of β. Our derivations further show that N_T decreases as increases even if D_min or D_max remain unchanged. Because D_max and the age of the largest individuals in a community are correlated, albeit weakly, we argue that the interdependent relationships among the numerical values of α, β, N_T, and shed light on the extent to which communities have experienced recent global disturbance. These predicted relationships receive strong statistical support using two large datasets spanning a broad spectrum of tree‐dominated communities.     

西双版纳地区不同胶农(林)复合系统的植物水分利用效率比较

当前,西双版纳地区大面积橡胶单一种植林已引发了诸多的生态环境问题,为解决这些问题同时协调当地的经济发展,农林复合系统被生态学者们认为是最好的解决办法。然而目前关于不同间作模式下橡胶树水分利用效率研究还很少。因此,于2013－2014年的雨季中期(8月)和末期(11月)、雾凉季(1月)、干热季(3月),分别测定了中国科学院西双版纳热带植物园内四种不同胶农(林)复合系统(橡胶—叶茶、橡胶—咖啡、橡胶—大叶千斤拔、橡胶—可可复合系统)及单层橡胶林的土壤含水量、橡胶树及其林下间作植物的枝条凌晨水势和正午水势,以及它们植物叶片的δ13 C值,分析了各胶农(林)复合系统内橡胶树的水分利用效率,以期遴选出水分关系配置合理的复合橡胶林栽培模式,为环境友好型橡胶种植林的建设和推广提供相关的参考依据和理论支持。结果表明：除橡胶—可可复合系统以外,其余胶农(林)复合系统内的橡胶树水分利用效率值均高于单层橡胶林;橡胶—大叶千斤拔复合系统的土壤含水量显著高于其它复合系统;橡胶—叶茶复合系统的土壤含水量虽然低于橡胶—大叶千斤拔复合系统,但其最为稳定、季节变化小;橡胶—咖啡复合系统的水分利用效率最高最稳定,即使受到寒害也没有引起明显变化;而橡胶—可可复合系统的作用不明显,所有特征都与单层橡胶林相似。这表明除了橡胶—可可复合系统外,其他3种胶农(林)复合系统都显著地缓解了橡胶树在旱季所遭受的水分胁迫,同时也能有效地抵御突发性天气灾害。     

Plant presence and species combination, but not diversity, influence denitrifier activity and the composition of nirK-type denitrifier communities in grassland soil

To explore potential links between plant communities, soil denitrifiers and denitrifier function, the impact of presence, diversity (i.e. species richness) and plant combination on nirK -type denitrifier community composition and on denitrifier activity was studied in artificial grassland plant assemblages over two consecutive years. Mesocosms containing zero, four and eight species and different combinations of two species were set up. Differences in denitrifier community composition were analysed by canonical correspondence analyses following terminal restriction fragment length polymorphism analysis of PCR-amplified nirK gene fragments coding for the copper-containing nitrite reductase. As a measure of denitrifier function, denitrifier enzyme activity (DEA) was determined in the soil samples. The presence as well as the combination of plants and sampling time, but not plant diversity, affected the composition of the nirK -type denitrifier community and DEA. Denitrifier activity significantly increased in the presence of plants, especially when they were growing during summer and autumn. Overall, we found a strong and direct linkage of denitrifier community composition and functioning, but also that plants had additional effects on denitrifier function that could not be solely explained by their effects on nirK -type denitrifier community composition.     

河北省塞罕坝保护区天然植物群落数量分类

运用双向指示种(TWINSPAN)和除趋势典范对应分析(DCCA)等方法定量分析了河北省塞罕坝保护区天然植物群落分布与环境因子的关系.结果表明: 塞罕坝保护区天然植物群落可划分为8种类型,即地榆+异穗苔草+金莲花群落、地榆+老芒麦+毛蕊老鹳草群落、披针叶苔草+铁丝草群落、柔毛绣线菊-铁杆蒿群落、山杏+柔毛绣线菊-铁杆蒿+披针叶苔草群落、蒙古栎+硕桦-胡枝子+柔毛绣线菊-披针叶苔草群落、白桦+山杨-毛榛+山刺玫-糙苏+披针叶苔草+唐松草群落、云杉+白桦-山刺玫+河北柳-披针叶苔草+节节草群落;DCCA分析表明,坡位和土壤养分是影响塞罕坝保护区天然植物群落空间分布的主要因子.地形、空间和土壤因子解释了物种格局变异的34.02%,其中,土壤因子占15.67%,地形因子占10.05%,空间因子占6.00%.在各类因子间的交互作用(2.30%)中,土壤和地形因子的交互作用最大(0.93%),土壤、地形和空间因子三者的交互作用最小(0.16%).65.98%未能解释的部分,可能归因于未被选取的因子如种间的协同和竞争作用或者人为干扰.     

意大利苍耳入侵对本地植物群落物种多样性和稳定性的影响——以乌鲁木齐市为例

研究外来植物不同程度入侵对区域群落结构和植物群落物种多样性的影响对评价其对生态系统的危害具有重要意义。以入侵植物以意大利苍耳(Xanthium italicum)为主要研究对象,选择意大利苍耳危害较明显且分布面积较大的中国新疆乌鲁木齐市米东区为研究区域进行植物样方调查,以意大利苍耳和其共生的本地植物为切入点,以物种多样性指数、群落稳定性、群落可入侵性、影响程度指数、入侵植物的竞争优势和入侵强度来探究不同入侵程度下的本地植物群落物种多样性和群落稳定性的变化。结果表明:(1)与未入侵地相比,意大利苍耳轻度入侵显著增加了本地植物群落的物种多样性(P ＜ 0.05),而重度入侵显著降低了本地植物群落的物种多样性(P ＜ 0.05)。(2)在意大利苍耳入侵的群落中,群落稳定性由轻度入侵水平到重度入侵水平降低了25%,而群落可入侵性、意大利苍耳的竞争优势指数和入侵强度指数分别增加了77%、79%和83%。(3)在轻度入侵水平下,意大利苍耳对本植物群落物种多样性、群落稳定性和群落物种数的影响程度指数 ＜ 0,产生了积极影响;相反,在轻中度和重度入侵水平下意大利苍耳对本植物群落物种多样性、群落稳定性和群落物种数的影响程度指数 ＞ 0,产生了负面影响。(4)本地植物群落多样性与群落稳定性均呈正相关,但与群落可入侵性呈负相关(P ＜ 0.05)。(5)Shannon-Wiener指数对群落的稳定性的直接通经系数最大,为0.828;Simpson''s指数对群落可入侵性的直接通经系数最大,为0.932。由此可见,意大利苍耳在中度和重度入侵对植物群落结构产生巨大影响,而作为"一带一路"的核心和枢纽地带的新疆,将会对其脆弱的生态系统和土著物种的多样性造成不可估量的影响。应在入侵初期对其进行控制与铲除,防止意大利苍耳等有害外来入侵种的入侵和进一步扩散与蔓延。     

北京永定河-海河干流河岸带植物的区系分析

探讨了北京永定河-海河干流河岸带植物区系特征。结果表明,河岸带植被中共有维管束植物37科100属134种,其中包括种子植物36科100属133种,蕨类植物1科1种。北京永定河-海河干流河岸带植物种类比较丰富,其中,在科的组成结构上,植物种类主要集中于少数几个大科如为禾本科和菊科,而多数科只有少数种或单种。在属的组成结构上,主要以单种属和小属为主。对其中种子植物的植物区系分布类型在种级水平上进行了分析,结果表明:河岸带共有4大类区系性质成分和16个地理成分类型,总体呈温带特性,各类温带分布类型67种,占河岸带植物总种数的50%。各河段河岸带植物区系结构存在差异:永定河山峡段与海河干流段区系结构比较相近,各结构在植物种所占比例上的排序为温带类世界类热带类亚洲类;而大部分长期干涸的永定河平原段,则温带类热带类世界类亚洲类。     

Vegetation structure,species life span,and exotic status elucidate plant succession in a limestone quarry reclamation

An understanding of the processes involved in plant succession is pivotal in achieving an effective site restoration. In a former limestone quarry (northeastern Italy), we explored the effects of a technical reclamation on the plant community using changes in cover of vegetation layers and two sensitive plant traits (i.e. exotic status and life span), with a chronosequence approach. Four reclaimed areas of different ages (from 8 to 35 years old) and natural vegetation in the surroundings were investigated with seven permanent plots each, for a total of 35. Changes in vegetation layers and species richness of both exotic status and life span were analyzed by generalized linear (mixed) models. Relations with plant community assembly were also considered, using a multivariate approach. Both vegetation layers and plant traits were affected by the age of reclaimed areas, evidencing the main changes in plant succession. Annual and exotic species decreased toward the mature stages of reclamation and target vegetation, whereas overall plant diversity (species richness) was stable. Our findings show that both vegetation layer changes and plant traits can be used to assess the degree to which reclamation efforts produce results that approach the restoration of a natural vegetation reference. Implementation of management practices aimed at favoring native perennial species (e.g. appropriate seed mixtures, mowing, tree, and shrub planting) could limit weed‐control efforts, representing a reasonable trade‐off between biodiversity promotion and invasive plant control.     

The effects of water pollution on the phylogenetic community structure of aquatic plants in the East Tiaoxi River,China

1. Water pollution is one of the most serious aquatic environmental problems worldwide. In China, recent agricultural and industrial development has resulted in rapid changes in aquatic ecosystems. Here, we reveal the effects of water pollution on the phylogenetic community structure of aquatic macrophytes in the Tiaoxi River, China.
2. We placed a rectangular plot at 47 sites within the Tiaoxi River from the mouth of the river to 88.5 km upstream, in which we recorded species abundance and measured 22 physico-chemical variables. Bayesian phylogeny using the rbcL and matK gene sequences was employed to quantify phylogenetic α- and β-diversity, and test the phylogenetic signal in four growth forms: emergent, floating-leaved, free-floating, and submerged.
3. Within communities, water contamination and phytoplankton abundance decreased species richness and phylogenetic diversity, which resulted in phylogenetic clustering; species within communities were more closely related to each other than expected. Between communities, differences in geographical distance and phytoplankton abundance resulted in phylogenetic dissimilarity among plots. Aquatic macrophytes showed phylogenetic signals in which related species responded more similarly to disturbance.
4. Thus, the observed patterns could be explained by environmental filtering and suggested that water pollution by human activity has added more filters to the existing environmental filters that drive the species assembly of macrophyte communities.

     

COMMUNITY COMPOSITION AND NICHE CHANGE CHARACTERISTICS OF DOMINANT SPECIES IN THE WIND-BREAKING AND SAND-FIXING FOREST, XINJIANG, CHINA

 以塔里木河下游绿洲外围大型防风固沙林为研究对象, 采用基于Simpson多样性指数的生态位宽度公式和Pianka生态位重叠测度公式, 在群落梯度上按重要值大小筛选出优势种群进行生态位分析, 探讨这些群落在4~7年的发育过程中生态位变化特点。结果表明: 1)经过4年的发育, 植物种组成简单的人工防风固沙林由于乡土植物种的侵入, 演变成为人工-天然植物群落, 不同地段群落中的优势种群发生了较大的变化, 优势种群共7个。芦苇(Phragmites communis)、花花柴(Karelinia caspica)和盐生草(Halogeton glomeratus)这3个乡土植物种侵入后逐渐成为优势种群, 而原人工群落主要建群种宁夏枸杞(Lycium barbarum)种群逐渐消退; 7年后, 优势种群共6个。由于水分条件的变化, 多枝柽柳(Tamarix ramosissima)成为优势种群, 而芦苇降为亚优势种群, 盐生草种群发生消退; 2)人工-天然植物群落中优势种群以耐旱耐盐碱植物占主要优势向占绝对优势的方向发展, 其生态位宽度变化幅度为0.56~0.86, 生态位宽度排序为芦苇>花花柴>头状沙拐枣(Calligonum caput-medusae)>沙枣(Elaeagnus angustifolia)>胡杨(Populus euphratica)>多枝柽柳>梭梭(Haloxylon ammodendron)>盐生草; 3)生态位重叠最大值发生在头状沙拐枣和胡杨种群之间; 4)在乡土植物种向人工群落侵入的过程中, 生态位宽度较大(或较小)的种群, 它们所构成的种对间生态位重叠既有较大的, 也有较小的, 可见生态位宽度与生态位重叠程度无相关性; 表明在现阶段群落演变中, 植物对环境资源存在着激烈的竞争和高的空间异质性。     

碧塔海湿地不同水分梯度下土壤真菌群落结构及功能类群研究

【目的】通过对碧塔海湿地不同水分梯度下土壤真菌群落结构及功能类群的分析,以期为湿地资源管理和生态恢复提供参考。【方法】选择滇西北碧塔海湿地不同水分梯度下的土壤,包括常年淹水的沼泽湿地(swamp wetland,SW)、季节性淹水的沼泽化草甸(swamp meadow,SM)和无淹水的草甸(meadow,M),利用Illumina高通量测序和FUNGuild比较分析不同水分梯度下土壤真菌群落结构和功能类群,并探究环境因子对真菌群落的影响。【结果】碧塔海湿地土壤真菌α多样性在不同水分梯度上无显著差异。非度量多维尺度分析和相似性分析表明真菌β多样性在不同水分梯度上存在显著的差异(R=0.501,P=0.001)。碧塔海湿地中真菌优势门为子囊菌门、担子菌门、隐菌门和被孢霉门。在不同水分梯度上担子菌门、被孢霉门和隐真菌门丰度存在显著差异(P<0.05)。优势科为火丝菌科、被孢霉科、古生菌科和珊瑚菌科(P<0.05)。相关分析显示,土壤pH、总氮、硝态氮、铵态氮、铁、钾、蔗糖酶和植物PCoA1与真菌α多样性呈显著相关(P<0.05)。冗余分析和相关性热图分析结果表明,含水率、铵...     

围封和放牧对科尔沁沙地植物群落种间关联的影响

为明确围封和放牧对科尔沁沙地植物群落种间关联的影响,在对植物群落进行样方调查的基础上,采用方差比率法（VR）、χ²检验、Ochiai指数、Spearman秩相关分析对种间关联性及相关性进行研究,得出如下结论：（1）围封和放牧改变了群落物种组成,围封群落出现30个物种,主要物种16个;放牧群落出现物种21个,主要物种13个。（2）VR值显示围封和放牧群落总体均呈正关联性,χ²检验表明围封群落正联结显著率大于负联结显著率,主要物种间显著联结率为27.5%,放牧群落仅有显著正联结种对4个,占6.06%,OI值与χ²检验结果基本一致。（3） Spearman秩相关分析表明,围封群落显著正相关对数略高于显著负相关对数,放牧群落则相反,且围封群落显著相关水平种对占比（44.17%）高于放牧群落（12.82%）,故围封群落处于稳定发展阶段,而放牧群落处于退化阶段。     

Plant coexistence in coastal heaths: Between- and within-habitat effects of competition,disturbance and predation in the post-fire environment

Abstract Previous experiments on post-fire establishment of two obligate seeders and two resprouting species suggested that initial establishment processes differ between wet- and dry-heath habitats. Disturbance, interspecific competition between seedlings and between seedlings and adults, and access for potential predators were manipulated in the field after a fire to identify mechanisms to explain between- and witm'n-habitat species coexistence. When soil surfaces are disturbed or seeds are buried, dry-heath species can establish in the wet heath. Under natural conditions, however, wet heath is rarely disturbed by animal foragers and lack of safe sites may preclude establishment of dry-heath species. In contrast, dry heath is often disturbed by ground foragers such as bandicoots and safe sites are plentiful for establishment of all heath species. Nevertheless, while wet-heath species can establish in dry heath, their seedlings are apparently unable to survive there due to the drier conditions. No evidence for competition among species was detected in either type of habitat during the first 3 years of the experiment, even at elevated seedling densities. Lack of early competition and unsaturated seed-banks may promote coexistence of species. Seedling predation from vertebrates was low and did not appear to influence patterns of coexistence within or between habitats. In terms of community theory we suggest that several interacting mechanisms are responsible for community structure in heaths after a fire. Chance and microsite disturbance are important during dispersal, while resources are critical during establishment and early survival of seedling populations. In these heath systems where fires burn extensive areas, seed-banks may be more important in temporal storage of species than patch or spatial storage as a mechanism for maintaining coexistence and plant diversity.     

北京市延庆采砂迹地型湿地植被群落分类与演替分析

采用TWISPAN分析方法,对北京市延庆采矿迹地湿地40个样地51种植物进行了分类排序,将群落类型划分为7个类型,即茵陈蒿-狗尾草-黄花蒿群落、野艾蒿-茵陈蒿-尖叶胡枝子-狗尾草群落、野艾蒿-茵陈蒿-狗尾草-野大豆-苣荬菜群落、狗尾草-苍耳-黄香草木犀-虎尾草群落、狼拔草-野艾蒿-旋覆花-大籽蒿-芦苇群落、香蒲-芦苇-茭白-野大豆-鬼针草群落和竹节灯心草-褐穗莎草-稗群落;同时运用双变量主坐标分析(DPCoA)对51种植物进行了排序分析,研究结果显示研究区存在两种演替规律,即由喜湿旱生耐淹水植物演替为喜旱旱生植物和由湿地挺水植物向湿生植物演替两种类型.对于采砂基地型湿地植被恢复不仅恢复土壤营养条件,调控湿地水分条件也是十分关键的.研究结论将为采砂迹地型湿地恢复提供科学支持.