Changes in tree species diversity and dominance across a disturbance gradient in Nepalese Sal (Shorea robusta Gaertn. f.) forests

Disturbance is often touted as a management tool, as moderate disturbance is believed to enhance diversity; thus an understanding of frequent and fluctuating disturbance regimes in forests and their effects on stand structure, dominance and diversity is very crucial. Here, the effects of different disturbance regimes, along a gradient, on diversity and dominance of five Shorea robusta Gaertn. f.-dominated forests were investigated in 25 one-ha plots in Nepal. A total of 67 tree species were recorded; of which 41 species were encountered in least disturbed and 10 species in beavily disturbed forest. Significant variations among forests were observed for all measures of alpha diversity. Alpha diversity measures declined linearly along a disturbance gradient while dominance increased linearly. Relative basal area of S. robusta increased as the level of disturbance increased, which in turn produced more than two-fold higher important value index in heavily disturbed forest than the least disturbed forest. All alpha diversity measures declined in an order of three with increasing relative basal area of S. robusta. The similarity in species composition between each pair of disturbed forests was generally low （Jaccard＇s similarity index 〈 57%）, suggesting a higher Beta diversity, It can be concluded that diversity of Sal forests declines with increasing magnitude of disturbance, which in turn favors a higher domi- nance of S. robusta. Controlling the population of the dominant species, mainly S. robusta, is recommended to enhance diversity and to achieve multiple-use forest management objectives.

Isolation and species diversity of arbuscular mycorrhizal fungi in the rhizosphere of Puccinellia tenuiflora of Songnen saline-alkaline grassland,China

Salinization has led to the deterioration of the ecological environment,affected the growth of plants,and hindered the development of agriculture and forestry.Arbuscular mycorrhizal(AM)fungi,as important soil microorganisms,play significant physiological and ecological roles in promoting plant nutrient absorption and improving soil structure.Puccinellia tenuiflora(Turcz.)Scribn.et Merr.in Songnen saline-alkaline grassland was selected as the research object to observe AM fungal colonization of the roots and explore the species and diversity of AM fungi in symbiotic association with P.tenuiflora.This study showed that AM fungi colonized in P.tenuiflora roots and formed a typical Arum-type mycorrhizal structure.A significant correlation was observed between vesicular abundance and the colonization intensity of mycorrhiza.Isolation and identification revealed 40 species of AM fungi in the rhizosphere of P.tenuiflora,belonging to 14 genera,of which two species could not be identified.The richness of the genus Glomus was the highest,accounting for 30%of the total species.Funneliformis mosseae and Rhizophagus intraradices were isolated from all the samples and were the species with the widest distribution in the rhizosphere of P.tenuiflora.Correlation analysis showed that pH only had a significant impact on the distribution of a few species,such as Glomus pustulatum,Diversispora spurca,Glomus aggregatum,Rhizophagus clarum,and Acaulospora foveata.The present study provides a theoretical basis for further exploring the resources of AM fungi in saline-alkaline soil.

Diversity and structural composition of species in dipterocarp forests:a study from Fasiakhali Wildlife Sanctuary, Bangladesh

Fasiakhali Wildlife Sanctuary is a protected area composed of tropical remnant rainforest that harbor substantial number of large,old Garjan（Dipterocarpus spp.）trees.The present study assessed composition,structure and diversity of the species in this protected area.A total of 32 trees species were recorded with DBH ≥ 11 cm belonging to 24 genera and 19 families.The forest is low in plant diversity as represented by Shannon–Wiener diversity and Simpson Dominance indices.Dipterocarpus turbinatus was the most dominant species with maximum relative density,frequency,dominance,and importance value index.Syzygium firmum and Tectona grandis followed in terms of dominance.The structural composition indicated higher number of individuals in the medium growth classes（41 to 〈 511 cm DBH and 16–20 m height ranges）,whereas D.turbinatus was the only species that dominated most of the growth classes.Poor stem density in lower growth classes indicated meager recruitment of regeneration which may be due to lower annual precipitation,increased grazing and encroachments.This study will help to understand the patterns of tree species composition and diversity in the remnant dipterocarp forests of Bangladesh.It will also contribute to identifying threatened plants to undertake D.turbinatus based conservation and sustainable management of the Fasiakhali Wildlife Sanctuary.

Relationship between diversity of forest plant species and environmental gradient in eastern mountainous area of Heilongjiang Province, China

Twenty-three secondary forest communities with different structure were selected in Mao＇er Mountain National Park of Heilongjiang Province, China to study the relationship between diversity of forest plant species and environmental gradient. The forest plant species diversity was analyzed by the diversity index, and the environmental factors was quantified by the method of Whittaker＇s quantification of environmental gradient. Meanwhile, β-diversity indexes of communities were calculated with similar measurements. The results showed that the Shannon-wiener diversity index of forest plant species increased with the increase of the environmental gradient, and the β-diversity indexes of communities showed a liner increase along with the change of environmental gradient.

Quantifyingα-diversity as a continuous function of location——a case study of a temperate forest

α-diversity describes species diversity at local scales.The Simpson’s and Shannon-Wiener indices are widely used to characterizeα-diversity based on species abundances within a fixed study site(e.g.,a quadrat or plot).Although such indices provide overall diversity estimates that can be analyzed,their values are not spatially continuous nor applicable in theory to any point within the study region,and thus they cannot be treated as spatial covariates for analyses of other variables.Herein,we extended the Simpson’s and Shannon-Wiener indices to create point estimates ofα-diversity for any location based on spatially explicit species occurrences within different bandwidths(i.e.,radii,with the location of interest as the center).For an arbitrary point in the study region,species occurrences within the circle plotting the bandwidth were weighted according to their distance from the center using a tri-cube kernel function,with occurrences closer to the center having greater weight than more distant ones.These novel kernel-basedα-diversity indices were tested using a tree dataset from a 400 m×400 m study region comprising a 200 m×200 m core region surrounded by a 100-m width buffer zone.Our newly extendedα-diversity indices did not disagree qualitatively with the traditional indices,and the former were slightly lower than the latter by<2%at medium and large band widths.The present work demonstrates the feasibility of using kernel-basedα-diversity indices to estimate diversity at any location in the study region and allows them to be used as quantifiable spatial covariates or predictors for other dependent variables of interest in future ecological studies.Spatially continuousα-diversity indices are useful to compare and monitor species trends in space and time,which is valuable for conservation practitioners.

The Rich-Gini-Simpson quadratic index of biodiversity

The Gini-Simpson quadratic index is a classic measure of diversity, widely used by ecologists. As shown recently, however, this index is not suitable for the measurement of beta diversity when the number of species is very large. The objective of this paper is to introduce the Rich- Gini-Simpson quadratic index which preserves all the qualities of the classic Gini-Simpson index but behaves very well even when the number of species is very large. The additive partitioning of species diversity using the Rich-Gini- Simpson quadratic index and an application from island biogeography are analyzed.

基于Shannon-Wiener指数的中国森林物种多样性保育价值评估方法

针对森林物种多样性保育价值评估尚缺乏逻辑推理方法的现状,提出了更为客观合理的Shannon-Wiener指数评估法。此方法通过森林生态系统的Shannon-Wiener多样性指数和林分面积,计算其物种多样性保育价值。基于此方法,利用第六次全国森林资源连续清查数据和来自中国森林生态系统定位研究网络(CFERN)所属生态站的数万个观测数据,对中国森林物种多样性保育价值进行了计算。结果表明,黑龙江和云南两省生物物种保育总价值在全国名列前茅,海南省尽管单价最高,但森林面积较小,其总价值较低。广大西北以及华北地区森林平均单位面积价值和总价值普遍较低。将全国39种林分类型归为如下几类:单价高总量少型、单价高总量大型、单价低总量少型、单价低总量大型和中间类型,针对不同的类群采取不同的保护政策,有利于推动生物多样性保护工作。与目前流行的支付意愿法(WTP)相比,Shannon-Wiener指数评估法的优越性在于:以生态系统的自然属性为基础,每个指标都具有明确的意义,评价结果更接近理论认识,且结果之间可比性强。

Assessment of Tree Diversity and Abundance in Rashad Natural Reserved Forest, South Kordofan, Sudan

This study aims to estimate the tree diversity status of Rashad Forest Reserves in the Rashad locality of the South Kordofan State of Sudan. For data collection, eight sample plots (20 × 20 m) were taken randomly, and parameters were determined: trees species diversity, composition, relative density, dominance, important value index, and species richness in the Rashad forest reserve. The results show that a total of 237 and 56 tree species, including 22 families, have been identified in the study area. Fabaceae family and species numbers have the highest number of 13 species in 8 genera, followed by Combretaceae with 8 species belonging to 3 different genera, Malvaceae with 5 species belonging to 4 different genera, Apocynaceae with 3 species belonging to 3 different genera. The Arecaceae, Burseraceae, Capparaceae, Euphorbiaceae, Meliaceae, and Rubiaceae families each had two species, and all the other 11 families had one species each. Among the 56 different tree species found within the reserve. The results also indicated that Tamarindus indica L. and Ziziphus spina-christi (L.) Desf. had the highest relative density and dominance of 4.64% and 11% respectively. Adansonia digitata L., Grewia villosa Willd, Vepris nobilis (Delile) Mziray had density and dominance of 4.80% and 9%. Followed by Anogeissus leiocarpa (DC.) Guill. & Perr, Adansonia digitata L., Catunaregam nilotica (Stapf) Tirveng. (Syn: Xeromphis nilotica (Stapf) Keay, Vangueria madagascariensis J. F. Gmel. with 3.38% and 8%, respectively. Eleven species recorded the least relative dominance of 0.42%. Shannon-Weiner diversity index (H’) value stood at 3.82. And as diversity indices varied with location depending on the species available within an ecological zone, Rashad forest reserve is blessed with a moderate diversity index.

Effect of exclosure ages on woody plant structure,diversity and regeneration potential in the western Tigray region of Ethiopia

Exclosure is a method of rehabilitating degraded lands by protecting them from the interference of animals and from human encroachment, and is used to regenerate native vegetation as a way to reduce soil erosion, increase rain water infiltration and provide fodder and woody biomass in degraded grazing lands. Therefore, we studied woody plant structure, diversity and regeneration potentials in 5-and 10-year grazing exclosures in comparison with open grazed sites in a semi-arid environment. Data on species diversity, abundance, structure, basal area, frequency, density, and regeneration status were collected from 270 sample plots. Forty-one woody species representing 20 families were identified, with 18, 28 and 38 species found in open grazed areas, and in 5-and 10-year grazing exclosures, respectively. The 10-year grazing exclosures had a higher(P <0.05) species richness and plant densities compared to the 5-year grazing exclosures and the open grazed areas. The population structure and regeneration status of woody species in both grazing exclosures showed an inverted J-shape, indicating a healthy regeneration status, whereas hampered regeneration was observed in open grazed areas. The establishment of grazing exclosures had positive effects in restoring woody plant diversity and improving vegetation structure and regeneration potentials of degraded grazing lands.

Global comparisons of beta diversity among mammals,birds,reptiles,and amphibians across spatial scales and taxonomic ranks

Beta diversity is the change in species composition among areas in a geographic region. The proportion of species shared between two areas often decreases when the distance separating them increases, leading to an increase in beta diversity. This study compares beta diversity among four classes of terrestrial vertebrates （mammals, birds, reptiles, and amphibians） at both regional （biogeographic realm） and global extents, using the same sets of faunal sample units for all four groups in each comparison. Beta diversity is lower for the two endothermic taxa （birds and mammals） than for the two ectothermic taxa （reptiles and amphibians） in all six biogeographic realms examined. When the four taxa in the six biogeographic realms are combined, beta diversity at the species rank is higher than that of the genus rank by a factor of 1.24, and is higher than that of the family rank by a factor of 1.85. The ratio of beta diversity at the genus rank to that at the family rank is 1.50. Beta diversity is slightly higher for ecoregions of 5000-99,999 km^2 than for ecoregions of 100,000-5,000,000 km^2.

Evaluation of Broadleaf Tree Diversity at the Basin Scale—In Case of Artificial <i>Chamaecyparis obtusa</i>Forests

In recent years, the various functions required of forests, especially the conservation of biodiversity, have been attracting increasing attention in Japan and worldwide. In Japan, 67% of national land is covered by forest, 41% of which is artificial forest (i.e., plantations). Therefore, forest biodiversity conservation efforts should also target artificial forests. In this paper, we seek to promote sustainable forest management that considers biodiversity conservation by examining indices that can be used by forest managers to evaluate the diversity of broadleaf trees. The result was that evaluation of broadleaf tree diversity in artificial forests at a basin scale was possible by combining several types of indicators.

Can picnic influence floral diversity and vitality of trees in Bhawal National Park of Bangladesh?

We examined the impact of picnic activities on forest diversity, structure, regeneration and vitality of tree species in the Bhawal National Park of Bangladesh. The study area was classified as a non-used, occasionally used and frequently used area on the basis of the intensity of the picnic activities. A total of 43 plant species were enumerated in the whole study area. The highest plant species richness （41 species） was observed in the non-used area whereas the lowest species richness （11 species） in the frequently used area. The diversity index decreased with the increase of picnic intensity whereas the concentration of dominance increased. Density of all plant groups except mature trees, and the basal area of the mature trees showed a declining trend from the non-used to frequently used area. The frequently used area exhibited very poor regeneration. Tree vitality decreased with the increase of picnic intensity. The relevance of our study as a basis for further research to determine the impact of tourism on biodiversity in Bangladesh is discussed.

Bayesian Estimation of Shrubs Diversity in Rangelands under Two Management Systems in Northern Syria

The diversity of shrubs in rangelands of northern Syria is affected by the grazing management systems restricted by the increase in human and livestock populations. To describe and estimate diversity and compare the rangeland grazing management treatments, two popular indices for diversity, the Shannon index and the Simpson index, were studied for the four combinations of two sites, Hammam and Obeisan, and two grazing methods, Closed and Open, using frequentist and Bayesian approaches. We simulated the a priori and a-posteriori distributions of the Shannon and Simpson diversity indices, where from a range of values for a constant in the a priori distribution the best value normalizing the distribution of the diversity indices was chosen. The Bayesian diversity estimates were higher than their frequentist counterparts and had lower standard errors. The grazing methods at each site and sites under each grazing method delivered significant diversity of shrub species. The Bayesian estimates resulted in lower p-values than the frequentist approach for two cases reflecting in Bayesian method’s higher power. Bayesian approach is recommended as it has a wider framework for inference on diversity studies.

Characterization of sugar diversity in floral and extra-floral nectar from the Coastal Coral Tree(Erythrina caffra Thunb.)in Southern California

The Coastal Coral Tree (Erythrina caffra Thunb.) produces floral nectar (FN) that serves to attract pollinating insects, but also secretes nectar from extra-floral (EFN) glands that serves to attract predatory insects, such as ants. While studies on myrmecophytes (i.e. specialized plants that attract and interact with ants) have primarily focused on interspecific evaluations of EFN chemistry, the Coastal Coral tree offers an opportunity to contrast intraspecific nectar chemistry with differing evolutionary and ecological functions. We hypothesized that the richness of (molecular) sugar species, relative concentrations, and diversity of sugars in FN and foliar EFN would diverge due to differences in the ecological role of the two types of nectar. High performance liquid chromatography with refractive index detection was used to identify the richness of sugar species (based on retention time), measure the relative concentrations, and evaluate the diversity of sugars in FN and foliar EFN secretions. We detected sugar species unique to each gland type and reported significant differences in the relative concentration of one sugar species common to both gland types. While the mean diversity index of sugars was similar for both gland types, the diversity of foliar EFN sugars was significantly more variable than that of FN sugars. The composition of FN showed little variation, and was reflective of its fundamental role in plant reproduction. Foliar EFN, however, demonstrated the variability expected of a context-dependent myrmecophyte that interacts with a facultative ant species assemblage across a mosaic of abiotic and biotic conditions.

大别山南坡森林植物群落物种多样性及其与海拔因子的关系

大别山地区植物资源丰富,区系组成复杂且起源古老,为连接华东、华北和华中三大植物区系的纽带,也是我国重要的生物多样性保护和水源涵养生态功能区。采用样方法,在大别山南坡的多枝尖、庵基坪和麒麟沟3个地区,沿着不同海拔高度选取了具有代表性的森林植物群落进行研究,从不同植物群落类型和层次的物种多样性、均匀度和丰富度及其与海拔因子的关系等方面,对大别山南坡的森林植物群落物种多样性进行综合分析。结果表明:1.共记录有植物108科270属449种,划分为20个森林植物群落类型;2.森林植物群落各层次物种丰富度表现为草本>乔木>灌木;Shannon-Wiener多样性指数和Simpson多样性指数呈现出乔木>灌木>草本;Pielou均匀度指数变化较为复杂;3.森林植物群落各层次的物种丰富度随海拔升高而下降;Shannon-Wiener指数和Simpson指数也表现为随着海拔升高而下降,但草本层在1400m之后有上升的趋势。Pielou指数在乔木层中表现为随着海拔的升高而下降,在草本层中表现为先下降后出现上升,在灌木层中则随着海拔的升高而上升,但其波动更为剧烈。本研究对大别山南坡森林植被大范围的采样观测研究,能够全面的展现大别山南坡森林植物的种类分布、空间组成等整体概况及其与海拔因子的关系,能为以后大别山南坡生物多样性的保护提供较为全面真实的数据,从而为大别山地区生物多样性的保护和可持续利用提供理论依据和实践意义。

阿勒泰林区草地群落中不同植物种在物种多样性中作用大小的探究

为探明各植物种在群落整体物种多样性中的作用,以阿勒泰林区草地群落为研究对象,采用“二值出现次数”野外调查方法,获得样方中各个植物种的出现次数和个体数量,从而计算出群落整体的物种多样性指数,以及构成群落的各个植物种不存在时的物种多样性指数,并利用这2个多样性指数的差值,来探讨群落中各个植物种对物种多样性的影响。结果表明:1)4个草地样地中,对物种多样性作用最大的植物种并非是其群落中的第一优势种,而是优势地位处于第2~6位的植物种;2)组成这4个样地群落的所有植物种都对群落的多样性起到增大的作用;3)物种在群落多样性中的作用,从总体上来看,呈现一种单峰的变化趋势,也就是随着物种优势地位的降低,对数式增加达到最大值,然后指数或线性下降,最终趋近于0。综合显示,不同草地群落中,对群落物种多样性作用最大的不是处于第一的优势种,虽然其占据了绝对优势地位,却降低了该群落的物种多样性。

山西省亚高山草甸群落组成及其多样性研究

【目的】以山西省从南到北分布的6个亚高山草甸为研究对象,探讨亚高山草甸的群落物种多样性和空间分布格局。【方法】采用有限样方内生物多样性的测定方法,测定了从南到北分布的6个亚高山草甸的物种组成和多样性指数,并比较了各草甸之间的群落相似性。【结果】6个亚高山草甸上共有172种植物,菊科、禾本科、蔷薇科、豆科分布较为广泛。各草甸物种多样性指数存在显著差异(P<0.05),其中大同市灵丘县亚高山草甸的群落物种多样性和丰富度指数最高,太原市娄烦县亚高山草甸的均匀度最高。从物种组成的群落相似性结果来看,吕梁市离石区亚高山草甸与大同市灵丘县亚高山草甸的物种组成相似性最高,忻州市宁武县亚高山草甸和大同市广灵县亚高山草甸的物种组成相似度最低。【结论】随着海拔的升高,亚高山草甸的多样性指数呈现随之降低的趋势。

甘肃连城国家级自然保护区蝶类多样性及种-多度分布

为明确甘肃连城国家级自然保护区蝶类多样性及种-多度分布情况,采用样线法,共选定8条样线进行蝴蝶标本采集,并对保护区内不同生境蝴蝶的多样性及种-多度分布进行分析。结果显示:共采集标本998号,隶属7科60属102种。保护区内优势科主要为粉蝶科(Pieridae)与蛱蝶科(Nymphalidae);优势种主要集中在粉蝶科,包括箭纹绢粉蝶(Aporia procris)、绢粉蝶(Aporia crataegi)、秦岭绢粉蝶(Aporia tsinglingica)等。区系分析表明,保护区内古北种占34.31%,东洋种占19.61%,广布种占46.08%,其中广布种占主导地位。各样线的多样性指数表明,样线Ⅴ(森林-灌丛-草甸)的科级多样性指数、优势度指数、物种丰富度指数及个体数均为最高,样线Ⅲ(森林)的属级多样性指数最高,样线Ⅱ(森林-灌丛)均匀度指数、种级多样性指数最高。相似性结果表明:样线Ⅲ(森林)和样线Ⅷ(森林)的相似性系数最高(0.509 1),呈中等相似;样线Ⅱ(森林-灌丛)和样线Ⅳ(森林-灌丛),样线Ⅲ(森林)和样线Ⅳ(森林-灌丛)相似性系数分别为0.230 8、0.229 7,位于极不相似区间,其余样线之间皆处于中等不相似。种-多度分析显示,保护区蝶类总体呈对数级正态分布,而样线Ⅴ与样线Ⅲ与Preston对数正态模型的吻合度较高,且样线Ⅴ的拟合效果最佳。表明样线Ⅴ(森林-灌丛-草甸)的生境条件优于其他样线,蝶类对其具有较高适应性。总体来看,保护区内生境良好,结构稳定,有利于蝴蝶群落生存。但不同生境及人为干扰等因素是影响蝴蝶多样性的主要原因,应对保护区内生境加强保护,减少对环境的破坏,从而使得保护区内生物多样性保持稳定水平。

西洞庭湖洲滩植物物种与功能多样性空间分布特征及其相关性

洞庭湖是长江中下游重要的通江湖泊,具有调蓄洪水和维护周边湿地生态系统及生物多样性等生态功能。研究植物群落物种多样性与功能多样性在异质环境条件下的特征及其相关关系,对认识植物群落分布规律、保护修复生态系统结构和功能具有重要意义。以西洞庭湖沅江和澧水水流方向上的洲滩植物群落为研究对象,采集优势种并测定其根和叶的碳氮磷含量、叶面积和根长等8个功能性状来研究群落间物种多样性差异、水流方向上洲滩群落功能多样性差异、物种多样性和群落功能多样性的关系及多样性指数间的相关性。研究结果表明:(1)沿水流方向不同位置植物群落物种多样性有显著差异。其中,沅江和澧水的水流方向上入湖口物种丰富度均较低;在所有调查区域中,沅江中游洲滩植物群落物种丰富度、香农指数均较高,出湖口的物种多样性最低。(2)澧水上游洲滩植物群落的碳氮磷含量的群落加权平均值(community weighted-mean,CWM)和Rao二次熵指数较高;澧水中游植物群落所有性状的CWM值和Rao二次熵指数最低;沅江上游植物群落具有较高的叶性状值,优势种中一年生草本植物的快速生长策略可能贡献较高的叶性状值。(3)西洞庭湖洲滩植物群落物种多样性与CWM值具有显著相关性,根碳含量的CWM值与物种丰富度、香农指数呈负相关;水流方向上不同位置植物群落物种多样性与Rao二次熵指数没有相关性。研究结果说明,沅、澧两水及沿水流方向不同调查区域的水文地貌特征差异对洲滩湿地植物群落物种和功能多样性都有影响,但拥有更高物种多样性(优势种组成、丰富度等)的植物群落适应能力并不一定更强。此外,沿水流方向,湖泊洲滩植物群落的物种与功能多样性趋异。因此,在西洞庭湖洲滩植物群落的保护和修复工作中需要综合考虑更多因素(如土壤、地形等),以便更全面地了解其生态系统的复杂性和特殊性。

大庆市蝶类多样性及其影响因素

为明确大庆市蝶类多样性及其影响因素,2016-2019年利用样线法对大庆市不同生境类型中的蝴蝶开展了调查研究。共观测到蝴蝶5780只,隶属6科29属36种。灰蝶科的个体数最多,蛱蝶科的物种数最多,是当地的优势类群;凤蝶科仅1种,是当地的稀有类群。优势种7个,常见种5个,少见种4个,稀有种20个。不同的生境蝶类群落种类与数量存在一定的差异,人为干扰小、植物群落结构最为复杂的新华草原蝶类的属数和种数最多,而人为干扰较强、植物群落单一的大庆龙凤湿地自然保护区最少;新华草原的蝶类多样性指数最高,大庆龙凤湿地自然保护区最低;新华草原的丰富度指数最高,乘风湖岸边最低。蝶类物种数、个体数、多样性指数及丰富度指数月度变化基本一致,且与月均温显著正相关(P<0.05),而与月降水量无相关性。综上,蝶类多样性与植被类型、月均温有明显的相关性。而相同气象条件下,植被类型是影响蝶类分布的重要因素。为了保护与丰富蝶类资源,建议植被单一的区域,进行适度的植被异质化建设。