Soil seed banks along elevational gradients in tropical, subtropical and subalpine forests in Yunnan Province, southwest China

Soil seed banks are a vital part of ecosystems and influence community dynamics and regeneration.Although soil seed banks in different habitats have been reported, how soil seed banks vary with elevational gradients in different climatic zones is still unknown. This paper investigates seed density,species composition and nonconstituent species of forest soil seed banks in Yunnan Province, southwest China. Similarity between the soil seed bank and standing vegetation was also examined. We collected soil samples from sites spanning 12 elevations in tropical rain forests, subtropical evergreen broadleaved forests and subalpine coniferous forests, and transported them to a glasshouse for germination trials for species identification. The soil seed banks of tropical and subtropical forests had much higher seed densities and species richness than those of subalpine forests. Seeds of woody species dominated the soil seed banks of tropical and subtropical forests, while herbs dominated those of subalpine forests.The nonconstituent species in the soil seed banks were all herbs and were most abundant in tropical forests, followed by subtropical forests but were completely absent from subalpine forests.

Different environmental factors drive tree species diversity along elevation gradients in three climatic zones in Yunnan,southern China

Elevational patterns of tree diversity are well studied worldwide.However,few studies have examined how seedlings respond to elevational gradients and whether their responses vary across climatic zones.In this study,we established three elevational transects in tropical,subtropical and subalpine mountain forests in Yunnan Province,southern China,to examine the responses of tree species and their seedlings to elevational gradients.Within each transect,we calculated species diversity indices and composition of both adult trees and seedlings at different elevations.For both adult trees and seedlings,we found that species diversity decreased with increasing elevation in both tropical and subalpine transects.Species composition showed significant elevational separation within all three transects.Many species had specific elevational preferences,but abundant tree species that occurred at specific elevations tended to have very limited recruitment in the understory.Our results highlight that the major factors that determine elevational distributions of tree species vary across climatic zones.Specifically,we found that the contribution of air temperature to tree species composition increased from tropical to subalpine transects,whereas the contribution of soil moisture decreased across these transects.

Advantage of Introducing Quantitative Light-Induced Fluorescence in School Dental Checkups

Background: Caries detection in school oral examinations insufficient accuracy. Objective: To evaluate advantages of introducing quantitative light-induced fluorescence-digital (QLF-D) in school oral examinations. Methods: Experiment No. 1. Early demineralized lesions in the upper and lower incisors and canines were visually inspected by three dentists and by QLF-D. The numbers of tooth planes with early demineralized lesions were compared between the methods. Experiment No. 2. Approximal demineralized lesions in molars were assessed by visual inspection, x-ray imaging, and QLF-D. The numbers of tooth planes with demineralized lesions were compared among the methods. Experiment No. 3. Plaque distribution was evaluated by QLF-D and a traditional staining method. The ratio of the diameter of plaque to tooth crown in the tooth axis direction in each method was calculated. The results were evaluated by Pearson’s correlation coefficient analysis and Bland-Altman plot. Results: Experiment No. 1. The three dentists found 0.67 tooth planes on average. QLF-D found 22 tooth planes with early demineralized lesions in the same samples. Experiment No. 2. Fourteen approximal tooth planes of molars were found to have demineralized lesions by x-ray imaging. QLF-D detected 71.4% of the tooth planes out of the 14, whereas visual inspection found 7.1%. Experiment No. 3. The Pearson’s correlation coefficient for the evaluations of plaque distribution between the QLF-D and traditional staining methods was 0.77 (P Conclusion: The results support introduction of QLF-D for use in school dental examinations.

基于塔吊的林冠科学研究进展及展望

林冠是生物圈中物种最为丰富的生境之一。长期以来,由于森林三维空间复杂性和林冠访问技术的限制,人们对林冠生物多样性、林冠的结构、功能和生态过程知之甚少。塔吊的应用突破了技术瓶颈,给林冠科学研究带来了深刻的变革。20世纪80年代以来,基于全球的林冠塔吊,国际上先后发起了林冠与土壤节肢动物多样性调查计划、林冠生物学计划、林冠CO_(2)富集和增温实验等一系列科学研究计划,回答了林冠“有什么、在哪里、怎样变”等基本问题,极大地推动了林冠科学的发展。本综述首先介绍了林冠访问技术及发展历程。随后,较为系统地梳理了基于塔吊平台发起的林冠研究计划,并从林冠生物多样性格局、林冠生态过程和林冠对全球变化的响应与适应3方面总结了相关研究进展。最后,从林冠访问技术所驱动的重大发现、林冠科学的主要研究框架、林冠科学的地域性与局限性等方面阐述了林冠科学研究计划带来的重要启示,并提出今后的林冠研究应更多关注“林冠-地面-土壤”3个层次相互关联形成的整体结构和功能系统,通过多元异构数据融合和人工智能技术,从多尺度、全方位解析全球变化背景下,整体森林的生物多样性格局、生态过程及其服务功能的响应与维持机制。

中国西南热带季风区石灰岩和非灰岩森林蕨类植物叶片性状的种间和种内适应性

在热带地区,石灰山森林(LFs)和非石灰山森林(NLFs)之间的植物通常表现出不同的分类学和功能型特征。蕨类植物是热带雨林的主要组成成分之一。然而,我们对LFs中分布的蕨类植物的形态和生理特征了解甚少。在本项研究中,我们评估了中国西南热带地区LFs和NLFs中的蕨类植物物种在7个叶片功能性状上的差异。我们测量了25种蕨类植物的叶片水分含量、形态特征(包括叶片大小、叶片厚度、气孔长度和气孔密度),以及生理特征(包括气孔导度和光合速率)。研究结果表明,与NLFs相比,LFs中蕨类植物的叶片更厚、更小,气孔密度和气孔导度更低,这可能反映了它们的水分利用策略。然而,当考虑系统发育关系时,这些差异变得不显著了,这表明系统发育保守性影响了LFs和NLFs的性状差异并最终影响了物种组成。在LFs和NLFs中共同出现的一些物种具有一定的种内性状变异,在LFs中气孔密度更低。这些发现表明,只有少数蕨类植物的水分利用策略能够同时适应LFs和NLFs,因此蕨类植物不太可能发生适应性辐射。

昆虫多样性三十年研究进展

当前,全球昆虫数量和多样性均处于下降趋势,而导致这一趋势的原因主要包括人为干扰及气候变化。本文基于森林、草地、农业、水生和土壤生态系统,以植食性、访花、捕食性、寄生性、食果以及食腐昆虫为重点功能昆虫群,综述了近三十年来国内外昆虫多样性研究领域的主要进展,并分析了发展趋势。近年来,昆虫多样性的研究维度不断拓展,形态多样性研究不断深入,系统发生多样性、功能多样性和遗传多样性等研究也显著加强。此外,昆虫多样性研究的空间尺度也逐步扩大,大尺度区域性研究甚至全球范围的调查持续增长。昆虫进化历史也被引入多样性格局研究中,并随着系统发生信息学方法的普及而被整合到生态系统建成和生物多样性形成机制研究中。未来需要加强关键昆虫类群整合分类学研究、功能性状多样性、林冠昆虫多样性、互作网络结构等方向的研究。

哀牢山4个海拔梯度树干节肢动物群落比较

作者在2013年4月(干季),运用树干喷雾法调查了哀牢山中山湿性常绿阔叶林2 000,2 200,2 400,2 600 m海拔的树干节肢动物群落.结果显示,所调查树干节肢动物群落隶属于7纲30个类群(目),主要由弹尾目、蜱螨目、蜘蛛目、双翅目、膜翅目、鞘翅目、啮虫目、半翅目同翅亚目、缨翅目等组成.不同海拔间树干节肢动物群落组成显著不同(基于Bray-Curtis相似性),其个体数量(密度)总体呈现出沿海拔升高而上升的趋势,但不同类群的个体密度随海拔梯度表现出不同的分布差异.树种和树皮粗糙度对树干节肢动物群落总体的影响不显著,但对少数节肢动物类群的密度呈现显著影响.表明海拔差异(温度和湿度)对树干节肢动物的影响显著高于微环境差异(树种和树皮粗糙度).

Environmental and spatial contributions to seedling and adult tree assembly across tropical,subtropical and subalpine elevational gradients

Aims Quantifying the relative importance of the mechanisms that drive community assembly in forests is a crucial issue in community ecol-ogy.The present study aims to understand the ways in which niche-based and spatially based processes influence community assembly in areas in different climatic conditions and how these processes change during the transition from seedling to adult.Methods In this study,we investigated how taxonomic and phylogenetic beta diversity in seedling and adult stages of forest trees change across three elevational transects in tropical,subtropical and subalpine for-ests in Southwest China,and the relationships of these changes to the environment and inter-site distances.We quantified the relative contribution of environmental conditions and spatial distribution to taxonomic and phylogenetic beta diversity of both seedling and adult life stages along each elevational transect.We also quantified the taxonomic and phylogenetic similarity between seedlings and adult trees along elevations.Important Findings Taxonomic and phylogenetic beta diversity of both seedlings and adult trees increased with an increase in both environmental distance and spatial distance in all three transects.On both taxonomic and phylo-genetic levels,the effects of environmental filtering and spatial dispos-ition varied between life stages and among forest types.Phylogenetic similarity between seedlings and adult trees increased with elevation,although the taxonomic similarity did not show clear elevational pat-terns.Our results suggest that the relative contribution of niche-based and space-based processes to taxonomic and phylogenetic assem-blages varies across major plant life stages and among forest types.Our findings also highlight the importance of ontogenetic stages for fully understanding community assembly of long-lived tree species.

Assessing temporal dynamics of predation and effectiveness of caterpillar visual defense using sawfly larval color and resting posture as a model

Caterpillars(Lepidoptera and Symphyta larvae)employ diverse visual defensive tactics,and effectiveness of such tactics may be highly dynamic across time due to seasonal changes in the predator assemblages and their preferences.However,this has rarely been studied especially in tropical regions.Here we assessed temporal changes in the defensive value of caterpillar color and shape,using six types of plasticine dummy caterpillars:three colors(green,black,and white)x two shapes(curled and straight).These dummy caterpillars were deployed five times over different seasons in tropical forests of Xishuangbanna(China)and,as a comparison,twice in a temperate forest of Hirosaki(Japan).The colors and shapes of dummy caterpillars simulate visual traits of black sawfly larvae which take the curled resting posture in tropical rainforests of Xishuangbanna,apparently masquerading excrements commonly found on plants,while in Hirosaki there is no black-curled sawfly larvae and few excrements on plants.Wc found no significant effects of caterpillar colors or shapes on predation in Hirosaki.In contrast,black and curled caterpillars received significantly lower predation by birds in Xishuangbanna constantly across time.However,we were unable to provide evidence that the black-curled sawfly larvae are masquerading as excrements.Shapes of the dummy caterpillars also affected the predation by ants and parasitoid wasps at certain times.This is the first report on ecological function of the curled posture of sawfly larvae,and we demonstrated the importance to assess the temporal dynamics of predation and effectiveness of defensive tactics in tropical forests.

日本山区铁路公司将3000系列电力动车组投入运营

日本山区铁路公司已将两列新型3000系列电力动车组(EMU)投入运营。介绍了该型动车组的结构特点。