首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 93 毫秒
1.
分别采用物种丰富度、物种多样性指数和群落均匀度等指标对浙江省大雷山夏蜡梅群落植物物种多样性进行测定,并通过相关分析对各种指数与土壤因子的关系进行研究。据10个样地统计,共有维管植物74科、165属、193种。从种子植物属的地理成分来看,温带分布的类型居多。不同群落木本植物的物种丰富度和多样性指数以杉木+木荷林最高,群落均匀度以杉木林最高,毛竹林的各项指数最低。草本植物的物种丰富度以杉木+马尾松林最高,杉木林最低;多样性指数和群落均匀度以竹林最高,短柄枹+格药柃林最低。在不同群落的垂直结构中,乔木层的物种丰富度和多样性指数均小于灌木层,草本层的物种多样性在不同群落间变化较大。相关分析表明,夏蜡梅群落物种多样性与土壤有机质含量相关性较大,其中,木本植物物种多样性与有机质含量显著正相关,草本植物与有机质含量显著负相关。  相似文献   

2.
井冈山云锦杜鹃群落特征研究   总被引:1,自引:0,他引:1  
以井冈山云锦杜鹃群落10个样地调查资料为基础,对该群落的物种组成、区系成分、群落结构和物种多样性进行研究。结果表明:该群落有维管植物44科67属83种,其中蕨类植物有6科6属6种,裸子植物4科4属5种,被子植物34科57属72种;区系分析显示,该群落植物区系地理成分复杂,热带性成分和温带成分均占较大比例;群落为复层异龄结构,云锦杜鹃、交让木和猴头杜鹃是组成该群落的建群种;物种多样性分析显示,群落Simpson指数和Pielou指数较高,Shannon-Wiener指数和物种丰富度指数较低,物种多样性指数在样地间有一定差异,在群落不同层次未表现出一致的变化规律。  相似文献   

3.
【目的】鳞翅目刺蛾科(Lepidoptera:Limacodidae)昆虫是重要经济、行道林木的主要害虫,本试验旨在研究北京及周边地区刺蛾科昆虫的系统发育多样性,阐明其群落结构组成与环境因子之间的关系,为北京及周边地区林木害虫防治和生态系统环境保护提供科学依据。【方法】采用灯诱法于2010-2013年间进行样品采集,基于DNA条形码技术及形态特征对9个刺蛾科昆虫群落进行物种识别和鉴定,利用R软件包进行物种丰富度指数、多样性指数和系统发育多样性指数计算及相关性分析。【结果】9个群落间物种多样性和系统发育多样性之间存在差异,北部燕山地区具有较高的物种丰富度和系统发育多样性,可能与植物类型不同有关;通过多种方法分别计算系统发育多样性,结果表明系统发育多样性指数对于系统发育树构建方法和物种内遗传差异不敏感;系统发育多样性与环境因子相关性研究结果表明,该地区刺蛾科群落系统发育多样性与温度季节变化存在显著正相关性。【结论】北京及周边地区刺蛾科昆虫群落结构具有地理差异,温度季节变化可能会造成环境异质性的增加,从而增加了群落系统发育多样性的复杂度。  相似文献   

4.
为探讨喀斯特高原山区灌丛草地昆虫群落多样性.本研究于2018年9月-2019年8月使用"Z"字样方网捕法、陷阱法、黄盘诱集法三种相结合的方法对贵州省大方县星宿乡崔苏坝灌丛草地进行昆虫群落多样性的调查,采用单因素分析、线性回归分析、相关性分析探讨了灌丛草地昆虫群落多样性.本研究共获昆虫标本12481号,隶属8目77科,其中蚁科和蚊科为优势类群,分别占总个体数的35.045%和24.950%;从4个功能群昆虫个体数来看,其中杂食性功能群昆虫个体数量最大,占所有功能群昆虫总个体数的60.365%.研究区喀斯特灌丛草地昆虫群落多样性指数消长随着季节的更替而发生变化,其中昆虫物种数与丰富度的最高值和最低值分别出现在8月和1月;个体数最高值和最低值分别出现在5月和1月;均匀度最高值和最低值分别出现在11月和1月;多样性指数最高值与最低值分别出现在6月和1月;而优势度的最高值与最低值出现情况则与多样性指数相反;功能群昆虫中除植食性昆虫的最高值与最低值分别出现在5月和1月外,其余3个昆虫功能群的消长情况与昆虫群落多样性消长情况基本一致.相关性分析结果表明,喀斯特高原山区灌丛草地的环境因子与昆虫群落多样性均有一定的相关性,其中土壤温度、空气温度、植被物种数与之呈极显著正相关关系(P<0.01).  相似文献   

5.
浙江箬寮山百日青的群落生态学特征分析   总被引:4,自引:0,他引:4  
通过样方调查,应用物种辛富度,物种多样性指数和物种均匀度等数据对分布在浙江松阳箬寮山地百日青(Podocorpus neriifolius)分布区物种多样性进行了研究。结果表明,箬寮山地植物种类丰富,共有维管束植物52科95属148种。科属组成多样,区系成分复杂,热带分布有49属,占总属数的52.12%,多于温带性质的属。木本植物的物种丰富度和物种多样性指数明显大于草本植物,乔木层植物Simpson指数、Shannon—Wiener指数和Pielou均匀度指数分别为6.7751、3.1593和0.6418;灌木层的分别为11.6826、3.8044和0.6781;草本层的分别为4.5537、1.7418和0.5378。灌木层-乔木层-草本层的物种多样性依次递减。根据分布生境、群落结构和种类组成,可将该山地百日青分布的群落分为三个类型,即甜槠木荷林、木荷红楠林和猴头杜鹃林。  相似文献   

6.
桂西不同灌丛植物群落物种组成及其多样性   总被引:1,自引:0,他引:1  
该研究通过野外设定样方、每木检尺的方法,调查了桂西9个市县的10种不同灌丛类型群落,分析了灌丛群落优势种重要值、物种组成、生长指标和物种多样性指数等生物学特征。结果表明:桂西灌丛资源丰富、分布广泛、类型多样,在调查的10个群落类型中,共有灌木树种87种,隶属于47科78属,以大戟科、蔷薇科和马鞭草科的树种较多;草本56种,隶属于31科48属,以禾本科、菊科和蔷薇科为主。灌丛群落主要分为灌木层和草本层,灌木层盖度为30%~70%,灌木的平均高度介于0.75~3.25 m之间,一般不超过5 m;草本层盖度为3%~90%,草本的平均高度在0.4~1.3 m之间,一般在1 m以下。不同灌丛群落的优势种重要值、物种多样性均不同,单优势种群落的优势种重要值普遍较高;而多优势种群落的物种多样性指数较高,即多优势种群落的物种数量多、分布均匀、结构更加复杂和稳定。物种丰富度S、多样性指数H′、优势度指数D和均匀度指数E之间存在显著的正相关性。综合分析,群落9(白栎+马桑+火棘灌丛)和群落10(黄荆+灰毛浆果楝灌丛)的组成丰富、多样性水平较高。  相似文献   

7.
深圳南山区天然森林群落多样性及演替现状   总被引:33,自引:0,他引:33  
对南山区5个主要天然森林群落(铁榄群落、鼠刺 降真香群落、鸭脚木群落、假苹婆群落、水翁 假苹婆群落)的组成结构及物种多样性进行分析,并与相邻的香港地区地带性森林群落(黄桐群落)作比较。结果表明,依照亚热带及南亚热带森林群落演替规律,南山区天然林处于不同的演替发育阶段:铁榄群落处于演替第3阶段;鼠刺 降真香群落处于第4阶段;其它3个群落处于第5阶段,均未达到稳定的顶极群落阶段。随着铁榄群落、鼠刺 降真香群落、鸭脚木群落、假苹婆群落、水翁 假苹婆群落这个演替序列,物种丰富度的变化规律是:先逐渐上升,到达一个峰值,再缓慢下降。Shannon-Wiener指数和Pielous均匀度指数的变化规律与物种丰富度相同,Simpson指数变化曲线与这些指数相反。但这些指数反映的结果是一致的。综合多个指数分析,鸭脚木群落物种多样性最大,即当群落中阳生性树种与中生性树种优势度相差不大时。群落具有最大的物种多样性。多样性比较结果显示,南山森林群落物种多样性大大低于香港黄桐群落。5个群落的Shannon—Wiener指数在2.04~2.953之间,明显低于黄桐群落,其Shannon—Wiener指数为4.74;Simpson指数0.1~0.268,黄桐群落为0.05;Pielous均匀度指数64.2%~74%,黄桐群落为79%。南山森林群落物种多样性水平低下的状况与长期的人类干扰有关,必须尽快采取“封山育林”等相应措施来促进群落的保护和恢复。  相似文献   

8.
世界范围内,很多自然生态系统均在不同程度上受到了损害,喀斯特脆弱生态系统的退化是一个复合过程,喀斯特地区不同退化程度植被群落特征有何差异有待研究。该文采用样方法进行全面的调查,研究了桂西北喀斯特地区5个退化程度植被群落的物种组成、群落结构特征和物种多样性。结果表明:(1)不同退化程度群落物种组成和生活型组成有较大差异,潜在退化群落科属种丰富度最高,沿着退化程度递增的梯度,群落乔木树种逐渐减少至消失,灌木比例呈先增后减的趋势,草本比例逐渐增加。(2)调查到维管束植物218种,隶属于86科168属;以大戟科、楝科、蔷薇科、马鞭草科、禾本科和肾蕨科植物为主;退化过程中,优势种的重要值逐渐降低,其在群落内的支配地位逐渐减弱,伴生种重要值逐渐升高。(3)退化过程中,群落结构趋于简单化,群落木本植物密度、高度和盖度逐渐减少。(4)不同退化程度植被群落乔灌草层物种多样性存在显著性差异,随着退化程度的增加,群落总植被物种丰富度指数、Shannon-Wiener多样性指数、Simpson优势度指数整体呈下降趋势。  相似文献   

9.
中国沙拐枣属天然群落特征及其物种多样性研究   总被引:4,自引:1,他引:3  
根据野外调查资料,应用生物多样性的原理和方法计测了群落的物种丰富度指数(R0、R1)、物种多样性指数(H′、D)、均匀度指数(E)以及优势度指数(C)以分析中国沙拐枣属天然群落的群落学特征。结果表明(1)中国沙拐枣属天然群落组成成分简单,共出现种子植物91种,分属22科62属,科属组成较为分散;生活型组成中1年生植物种类多,数量大,占总数的35.16%;沙拐枣属天然群落的垂直结构明显;(2)多样性分析表明,中国沙拐枣属天然群落物种组成单一,结构简单,其中群落多样性最低分别为塔克拉玛干沙拐枣(Calligonum roborowskii)群落和沙拐枣(C.mongolicum)(若羌)群落。群落多样性最高分别为沙拐枣(C.mongolicum)(采南)群落、小沙拐枣(C.pumilum)群落和艾比湖沙拐枣(C.ebi-nuzicum)群落。不同沙拐枣属植物所形成的群落差异主要表现在物种组成以及物种多样性水平,这种差异表现主要是1年生和多年生草本植物的物种多样性。(3)丰富度指数和物种多样性指数表现出基本一致的变化趋势,而生态优势度指数则表现相反的趋势。物种的丰富度指数和多样性指数与群落的结构以及立地环境条件等有密切的关系,结构复杂的群落较其它群落的多样性指数高,但由于特殊生境所形成的单优群落物种多样性指数则较低。  相似文献   

10.
山西霍山落叶阔叶林边缘效应的研究   总被引:7,自引:1,他引:6  
通过对山西霍山暖温带森林植被片断化后不同地带不同群落边缘的边缘植被的调查,运用Shannon-Wiener物种多样性指数(D),Simpson生态优势度指数(C),边缘效应强度指数(Z)和各层次各物种的重要值(IV),对霍山暖温带落叶阔叶林的边缘效应进行了初步的研究。研究表明:(1)在群落的各种边缘区,边缘具有增大物种多样性的作用.(2)距林道边缘10m左右,物种多样性指数呈一峰值,10m以后指数逐渐降低并趋于平缓,在距自然空地5~10m处是物种多样性指数最高的地段,随后,随进入林内而逐渐减少并趋于平缓,在人工林的交错区内是物种多样性指数的高峰段,随后进入林内逐渐减少。距灌木丛交错区10m以后物种多样性指数出现高峰,随后逐渐减少并趋于平缓.(3)连翘、羊胡子草等植物是群落的优势种,且大多呈连续分布。  相似文献   

11.
Variation in cone size, seed number per cone, seed potential, seed efficiency, seed morphology and seed germination behavior of Pinus pinea and its relation to stand conditions was analyzed. Data were collected from P. pinea forest in Strofylia, southern Greece, a forest that belongs to the Natura 2000 European network and the RAMSAR convention and is characterized by the absence of regeneration for many decades. The pine stands found in the area were distinguished into five categories according to a previous study and our observations, regarding stand age, canopy cover and the degree of stress by human pressure. The categories are: (I) young artificial, (II) closed-mature, (III) open-mature, (IV) over-mature stands and (V) highly degraded stands. Cones were collected from all stand types and their morphological characteristics as well as their seed production were measured. Seeds were extracted from the collected cones, measured and their germination behavior was tested. The findings showed that the over-mature and the high degraded stands and to a lesser extent, the closed-mature stands, produced significantly smaller cones with a lower seed potential, a lower number of filled seeds per cone, a greater number of not fully developed seeds and reduced seed morphological characteristics than the young and open-mature stands. However, the seed germination behavior of fully developed seeds was only slightly affected by the stand type.  相似文献   

12.
An accepted criterion for measuring the success of ecosystem restoration is the return of biodiversity relative to intact reference ecosystems. The emerging global carbon economy has made landscape‐scale restoration of severely degraded Portulacaria afra (spekboom)‐dominated subtropical thicket, by planting multiple rows of spekboom truncheons, a viable land‐use option. Although large amounts of carbon are sequestered when planting a monoculture of spekboom, it is unknown whether this is associated with the return of other thicket biodiversity components. We used available carbon stock data from degraded, restored, and intact stands at one site, and sampled carbon stocks at restored stands at another site in the same plant community. We also sampled plant community composition at both sites. The total carbon stock of the oldest (50 years) post‐restoration stand (250.8 ± 14 t C ha?1) approximated that of intact stands (245 t C ha?1) and we observed a general increase in carbon content with restoration age (71.4 ± 24 t C ha?1 after 35 and 167.9 ± 20 t C ha?1 after 50 years). A multiple correspondence analysis separated degraded stands from stands under restoration based on ground cover, floristic composition, and total carbon stock. Older post‐restoration and intact stands were clustered according to woody canopy recruit abundance. Our results suggest that spekboom is an ecosystem engineer that promotes spontaneous return of canopy species and other components of thicket biodiversity. The spekboom canopy creates a cooler micro‐climate and a dense litter layer, both likely to favor the recruitment of other canopy species.  相似文献   

13.
Mangrove forests are active carbon sinks and important for nutrient cycling in coastal ecosystems. Restoration of degraded mangrove habitats enhances return of ecosystem goods and services, including carbon sequestration. Our objective was to assess the restoration of primary productivity of reforested mangrove stands in comparison with natural reference stands in Gazi Bay, Kenya. Litter fall data were collected in nine Rhizophora mucronata and Sonneratia alba monospecific stands by use of litter traps over 2 years. Litter was emptied monthly, dried, sorted, and weighed. The reforested and natural stands showed seasonality patterns only in the production of reproductive material. Leaves constituted the highest percentage to total litter fall. Litter productivity rates for the R. mucronata stands were not significantly different and ranged from 6.61–10.15 to 8.36–11.02 t ha?1 yr?1 for the restored and natural stands, respectively. The productivity of 5 years R. mucronata stands reached 5.22 t ha?1 yr?1 and was significantly different from other stands. Litter productivity rates for S. alba stands was 7.77–7.85 for the restored stands and 10.15 t ha?1 yr?1 for the natural stand but differences were not significant. Our results indicate that plantations of at least 11 years have attained litter productivity rates comparable to the natural forests. This suggests that productivity of replanted mangroves is likely to reach complete recovery by this age under the prevailing environmental conditions.  相似文献   

14.
Seed dispersal by Red fox (Vulpes vulpes), Stone marten (Martes foina), and Wild boar (Sus scrofa) was analyzed in an extensively degraded mosaic landscape in Sierra Nevada (SE Spain). The main objective was to determine whether seed dispersal by mammals was related to habitat degradation within a mosaic of adjacent degraded patches mixed with native forest and thereby to determine the potential role of mammals as seed dispersers in degraded landscape units. For three consecutive years, mammal feces were collected in the fruit production period, extracting all seeds of woody species found therein and analyzing their viability. Feces were collected in three different plots for each of five different landscape units: shrubland, native forest, and dense, cleared, and fenced reforestation stands. Seeds from 16 woody species (which represent more than a half of the total fleshy‐fruited woody species available) were recorded, although some agrarian species are also introduced in a low percentage of the scats. Seeds showed a high viability rate for all dispersed species, irrespective of the mammal disperser. No differences in species composition appeared in the overall landscape units or in the seed density between degraded habitats. Due to the small patch size, the high viability of dispersed seeds, and the large home range of the large mammals, these three animal species act as efficient seed dispersers for a diverse assemblage of woody plant species regardless of the habitat type within this degradation framework. This fact has important consequences for the biodiversity recuperation in these degraded habitats, principally in pine plantations.  相似文献   

15.
Questions: Does stand age influence the direction and rate of post‐fire successional dynamics in coastal Calluna heaths and can old degraded heath vegetation be restored through reintroduction of fire? Location: Coastal heaths in the Tarva archipelago, central Norway. Methods: We investigated revegetation dynamics after experimental fires set in young (8 years since last fire) and old (>50 years since last fire) grazed heath stands. A repeated measures design was used, with floristic data recorded in permanent plots in the post‐fire successions (n=12) over a 7‐year period. The data were analysed using multivariate ordination techniques (PCA, RDA and PRC) and mixed effects models. Results: The age of Calluna stands strongly influenced post‐fire succession, different trends due to age explained 10.4% of variation in floristic data. Young heath showed faster succession towards pre‐fire community composition than old heath, and this could partially be explained by succession‐related factors: young heath had lower cover of mosses and lichens in the pre‐burned vegetation, and lower cover of litter early in succession. Young heath had a less pronounced overall community response to fire than old heath. Vegetative regeneration of C. vulgaris was absent in both old and young heath, but Calluna still re‐established as the dominant species within 5–7 years in both young and old stands. Regeneration dynamics were also affected by habitat conditions, different trends due to habitat explained 6% of variation. Conclusions: Our study demonstrates that old stands do develop characteristic heathland vegetation and structure after fire, and while potential invasives into the system such as trees and rhizomatous species are present, they do not impair Calluna regeneration or vegetation development towards the target heathland community composition and structure. Further, as our young stands are only in their second fire rotation after restoration, we suggest that characteristic dynamics of managed heathlands can re‐establish relatively rapidly, even in severely degenerated sites (>50 years since last fire). Site‐specific factors also need to be considered. We conclude that there is restoration potential in old heaths, despite slow dynamics in the first rotation.  相似文献   

16.
We propose that nonharvest plantations could provide important opportunities for restoration of indigenous forest cover and related ecosystem services. We assessed the relative performance of three Podocarpaceae (podocarps) species planted into a degraded Ponderosa Pine (Pinus ponderosa) plantation, central North Island, New Zealand. We hypothesised that the degraded pine plantation overstorey could provide suitable conditions for the development of a podocarp‐dominated forest structure within ca. 50 years of underplanting and that podocarp growth would differ depending on the species suitability to the site. Rimu (Dacrydium cupressinum) significantly outperformed both Totara (Podocarpus totara) and Kahikatea (Dacrycarpus dacrydioides) in height and diameter growth. Rimu was now the structurally dominant tree where it occurred rather than pine. Per annum scaled carbon storage within Rimu stands was significantly greater than the Totara, Kahikatea or Pine stands. All podocarp species had attained a greater stand density compared to the pine overstorey. Possible reasons for the differing podocarp growth performance include different light requirements, response to soil nutrients, elevational distributions and frost susceptibility. There were significant differences in understorey species richness among the different stands of podocarp species. Underplanting accelerated successional development by incorporating late‐successional indigenous canopy dominants within the forest succession and overcame limitations imposed on forest succession at the site from its isolation from indigenous forest tree seed sources.  相似文献   

17.
Abstract. Vegetation and soil seed banks of a threatened Atlantic fen meadow community were studied using recent phytosociological records and seedling emergence from soil samples. Similarly managed but differently degraded stands that suffered different levels of species impoverishment were compared. The actual vegetation was related to a set of phytosociological references representing the subassociations of the community. DCA positions of reference relevés from the different subassociations were overlapping, suggesting that in all references many common species occur. Recent records were positioned in‐between the seed bank samples and the references. The soil seed banks of all stands were dominated by ordinary species. Most character species had at most sparse seed banks and no seedlings of locally extinct character species, mentioned in historic floristic records, were detected. In contrast species of pioneer and small‐sedge communities as well as those of heathlands were abundant in the seed banks. Based on the vertical distribution of seeds in the soil layers most fen meadow species were classified into transient or short‐term persistent seed bank types. We concluded that complete restoration of the Cirsio dissecti‐Molinietum without reintroduc‐tion is only likely in stands that were degraded only a few years ago. On the other hand, the presence of viable seeds of Nanocyperion and Parvocaricetea species is promising for the restoration of these communities even after decades. Recreation of pioneer habitats by sod cutting will preserve these species.  相似文献   

18.
Growth, biomass, carbon storage and nutrient (N, P and K) variations in 1 to 6-year-old chronosequence plantations of Gmelina arborea were studied in three degraded red lateritic sites in central India. Growth parameters (dbh, total height and number of branches) varied significantly due to difference in age and site quality, but tree density showed non-significant variation. Stand biomass ranged from 3.94 (1-year-old) to 53.67 Mgha(-1) (6-year-old) and stand carbon in 6-year-old plantations ranged from 24.12 to 31.12 Mgha(-1) at different sites. Among the tree components, the stem wood accounted for maximum C (56.25% at site 1) followed by branches (19.8% at site 3), roots (18.51% at site 2) and foliage (7.01% at site 3). Mean annual C accretion at 6 years age of plantation was highest in site 3 and it was 0.35, 2.66, 0.965 and 0.87 Mgha(-1) for leaf, stem, branches and roots, respectively. Quantity of nutrients increased with age. Total nitrogen accumulation in 6-year-old stands at the three sites ranged from 212.9 to 279.5 kgha(-1) with a mean annual storage of 238.43 kgha(-1) and total K ranged from 170.8 to 220.5 kgha(-1) with a mean annual storage of 189.93 kgha(-1). Phosphorous accumulation was lowest with a mean storage of 16.75 kgha(-1). The organic carbon and nutrients in the soils improved significantly after 6 years of G. arborea planting. Soil organic carbon increased from 8.46 to 14.02 Mgha(-1) within 6 years. At soil depths 0-20 cm, 21-40 cm and 41-60 cm, available N enhanced by 14.85%, 11.98% and 11.25%, K by 10%, 9.13% and 10.63%, whereas phosphorous declined by 26%, 23% and 20%, respectively. At 6 years, G. arborea stands sequestered 31.37 Mgha(-1) carbon. The nutrient management strategies in relation to carbon accretion in G. arborea stands on degraded lateritic sites are discussed.  相似文献   

19.
Evidence has been accumulating at the oligomer level that free radical-initiated DNA damage includes lesions in which two adjacent bases are both modified. Prominent examples are lesions in which a pyrimidine base is degraded to a formamido remnant and an adjacent guanine base is oxidized. An assay has been devised to detect double-base lesions based on the fact that the phosphoester bond 3' to a nuclesoside bearing the formamido lesion is resistant to hydrolysis by nuclease P1. The residual modified dinucleoside monophosphates obtained from a nuclease P1 (plus acid phosphatase) digest of DNA can be (32)P-postlabeled using T4 polynucleotide kinase. Using this assay the formamido single lesion and the formamido-8-oxoguanine double lesion were detected in calf thymus DNA after X-irradiation in oxygenated aqueous solution. The lesions were measured in the forms d(P(F)pG) and d(P(F)pG(H)), where P(F) stands for a pyrimidine nucleoside having the base degraded to a formamido remnant and G(H) stands for 8-oxo-deoxyguanosine. The yields in calf thymus DNA irradiated 60 Gy were 8.6 and 3.2 pmol/microgram DNA, respectively.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号