Energy Flow In Ecosystems Research Articles

暖温带森林生态系统林下灌木生物量相对生长模型

PDF HTML阅读 XML下载 导出引用 引用提醒 暖温带森林生态系统林下灌木生物量相对生长模型 DOI: 10.5846/stxb201311222789 作者: 作者单位: 中国科学院生态环境研究中心城市与区域生态国家重点实验室;,中国科学院生态环境研究中心城市与区域生态国家重点实验室,河北雾灵山国家级自然保护区管理局,河北雾灵山国家级自然保护区管理局,中国地质科学院水文地质环境地质研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 中国科学院战略性先导科技专项(XDA05050602,XDA05060102) Biomass allometric models for understory shrubs of warm temperate forest ecosystem Author: Affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences;2 College of Life Science, Hebei Normal University,State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:灌木层作为暖温带森林生态系统的重要组成部分,其生物量估算的精确性及便捷性,成为森林生态系统能量流动、物质循环研究的重要环节。目前可用于暖温带森林生态系统灌木层生物量估算的相对生长模型较少。以河北雾灵山国家级自然保护区暖温带森林生态系统为研究对象,建立了该区域15种常见灌木的相对生长模型。研究发现:15种灌木全株和单一器官的最优相对生长方程均以D2H为自变量,分别以幂函数W=a(D2H)b或二项式函数W=a+bD2H+c(D2H)2为最优化回归方程。统计分析结果显示:判断系数R2值介于0.7331-0.9992之间,显著性检验各参数P < 0.01,满足回归模型的适用性要求。对研究区域常见灌木全株生物量(WTU)的普适性研究发现:以D2H为自变量的二项式函数回归模型WTU=0.0362+297.03D2H-127.1(D2H)2,R2=0.9434,P < 0.01,普遍适用于除去六道木(Zabelia biflora)和照山白(Rhododendron micranthum)之外的13种灌木植物的生物量估算。此模型对以上2种植物不适用的原因有待进一步研究。 Abstract:The shrub layer is a very important component in the warm temperate forest ecosystem. Accurate and convenient estimation of shrub layer biomass is a key point in the studies of forest biomass, circulation of materials and energy flow of the whole forest ecosystem. Allometric model can serve as a good method to achieve this goal. Studies on this subject have been employed around the world, but few studies have been taken in warm temperate forest in China. Aiming at this point, an investigation on forest understory shrub allometric modeling was established during growing season in 2011 in the region of Hebei Wulingshan Natural Reserve, which has the most typical Warm Temperate forest ecosystem, in North China. Basing on research data of this investigation, biomass allometric models for 15 common shrub species are constructed. The 15 shrub species include: Deutzia grandiflora, Syringa reticulata var. mandshurica, Campylotropis macrocarpa, Rhododendron mucronulatum, Weigela florida, Corylus mandshurica, Zabelia biflora, Rhododendron micranthum, Spiraea trilobata, Hydrangea bretschneideri, Rhamnus bungeana, Philadelphus incanus, Berberis amurensis, Rosa davurica and Radix Acanthopanais. The models of W=a(D2H)b, W=a+bln(D2H) and W=a+bD2H+c(D2H)2 were employed for the selecting of the optimal allometric equation to the 15 shrub species. The research result shows that D2H (where D means basal diameter and H stands for plant height) is the optimal variable of all the biomass allometric models of single organ or total plant. Power function of W=a(D2H)b or quadratic function of W=a+bD2H+c (D2H)2 is selected as optimal allometric equation to the 15 shrub species separately. Statistic results show that R2 values are between 0.7331 and 0.9992 and P values are less than 0.01, which mean that the selected optimal equations are applicable to the biomass estimation of the shrub species in our study region. For more convenient application for the shrub biomass estimation in the warm temperate forest in North China, we classified and compared the allometric models of the total 15 shrub species to get a universal model for most of the normal shrubs in this region. The study of total plant biomass universal regression model shows that the quadratic function of WTU=0.0362+297.03D2H-127.1(D2H)2, (R2=0.9434 and P < 0.01) is applicable to 13 shrub species except for Zabelia biflora and Rhododendron micranthum among the 15 species. Further research is still required to explain why this model is not applicable to the rest 2 species. 参考文献 相似文献 引证文献

안정동위원소비 분석 기법의 이해: 시료의 전처리, 분석 및 자료의 해석과 적용

This review paper was written to provide background information as well as future application for aquatic ecologists interested in using stable isotope. table isotope techniques has proved to be an extremely useful to elucidate a ot of environmental and ecological problems. Stable isotopes have been used as possible tracers to identify sources, to quantify relative inputs in a system. When utilized carefully, stable isotope tools provides apparent advantages for the scientists to find out the processes of material cycles in various nvironments and energy flows in natural ecosystems.

Multi-scale biomass estimation of desert shrubs:a case study of Haloxylon ammodendron in the Gurbantunggut Desert,China

Shrubs are an important component of desert ecosystems.Their biomass allocation and biomass estimation are important indices to study the structure,function,mass,and energy flow of desert ecosystems. However,research on desert shrub biomasses is still limited.The current destructive biomass estimation is unsuitable for use in arid lands where the ecosystem is weak,so it is important to estimate the shrub biomass using models at multiple scales.In this study,the constructive shrub species Haloxylon ammodendron in the Junggar Desert was used as an example.A number of plant morphological parameters were chosen,and the aboveground(AGB)and belowground biomass(BGB)models were established at the individual plant,plot and regional scales using allometric(power function)equations.The biomass estimation was then performed using the same model.Based on the canopy volume(CH),the formula AGB=0.3628×CH0.9605 accurately reflected the AGB individual accumulation characteristics.The individual BGB was estimated using BGB=0.8737× AGB0.9394.The total canopy cover(TC)of H.ammodendron was an effective parameter to calculate the total AGB and BGB(TAGB=0.6757×TC1.1343,TBGB=0.6384×TC1.0959)in sampling plots with an area of 0.1 hm2.On a large,regional scale,the relative canopy cover(RC)had a positive effect on estimating the AGB and BGB densities(DAGB=0.0921×RC1.1343,DBGB=0.0796×RC1.0959),from which the total regional biomass storage of H.ammodendroncould be obtained.It showed that the issue of scaling was successfully resolved using the RC of the H.ammodendronbiomass density.There was no scale limit when RC was used.In future, the RC of H.ammodendron can also be obtained quickly through aerial photography,remote sensing,etc, thus the total AGB and BGB in relevant regions would be estimated accurately using the aforementioned biomass density models.

Assessing the impact of the urbanization process on net primary productivity in China in 1989–2000

Urban development affects the material circulation and energy flow of ecosystems, thereby affecting the Net Primary Productivity (NPP). The loss of NPP due to urban expansion was calculated integrating GLO-PEM with remote sensing and GIS techniques in China during the period of 1989–2000. Using urban expansion and the mean NPP for the different land use types in the fourteen regions, the total loss of NPP was calculated as 0.95 Tg C, which accounted for 0.03% of the national NPP of 1989. The total loss of NPP due to the transformation from cropland to urban land accounted for 91.93%, followed by forest (7.17%) and grassland (0.69%). However, the conversion from unused land, industrial and construction land, and water bodies to urban land resulted in an increase in the NPP. The regions locating in eastern China and middle China had large reductions in the total NPP due to urban expansion.

Structure and energy flow of Dianshan Lake ecosystem based on the Ecopath model

Dianshan Lake,the largest freshwater lake in Shanghai,covers an area of 62 km2 with mean depth of 2.0 m and provides drinking water for more than 10 million people.With the rapid development of industry and agri-culture in recent years,Dianshan Lake has become polluted by run-off and sewage,leading to blooms of blue-green algae in some parts of the lake.The self-cleaning ability of Dianshan Lake has been degraded,and city authorities have funded several research projects to explore the reasons for its ecological deterioration.Based on data from a bio-resources survey carried out between September 2008 and September 2009,a mass-balance model of trophic interactions was constructed using Ecopath with Ecosim(EwE,an ecological/ecosystem modeling software suite) to represent energy transfer through the trophic levels of the Dianshan Lake ecosystem.This is the first Ecopath model of Dianshan Lake and consisted of 21 functional groups,including birds,commercial fish species,phytoplankton,zooplankton,benthos,shrimp,mollusks,macrophytes and detritus.Each group repre-sented organisms with similar roles in the food web and covered the main trophic flow in Dianshan Lake.The re-sults show that total throughput was 4 098.50 tonne?km?2?a?1.The trophic levels of different groups ranged from 1 for detritus and phytoplankton to 3.92 for large predators,with water birds occupying the top level.Mixed trophic impact analysis indicated that both trawling and gillnet fishing were impacting components and the negative tro-phic impact of fishing on different groups was relatively high.Top-down or bottom-up control in several preda-tor–prey relationships demonstrated that some species can be used to control blue-green algal blooms can be con-trolled by some species in some areas.For example,Hypophthalmichthys molitrix had a negative trophic impact on algae due to their predatory relationship in the food web,while submerged and other macrophytes had little influ-ence on algae due to their competitive relationship in the food web and low biomass within the niche.The system network was mapped via network analysis into a linear food chain with five main trophic levels.Mean transfer efficiency was 11.3% from detritus and 12.3% from primary producers within the ecosystem,which was higher than nearby lakes.Transfer efficiency is only 7.0% from level I to level II and 3.3% from level V to VI,which indicated that the transfer efficiency of the Dianshan Lake ecosystem is imbalanced.The importance of discarded food and system re-cycling rate in the ecosystem was low;energy utilization rate could be increased.Most unused detritus was deposited on the bottom of lake and affected water transparency via wind and wave agitation.

Influence of plantation of an exotic mangrove species, Sonneratia caseolaris (L.) Engl., on macrobenthic infaunal community in Futian Mangrove National Nature Reserve, China

Sonneratia caseolaris, a superior mangrove species characterized by rapid growth and proliferation, has been introduced to Futian Mangrove National Nature Reserve, Shenzhen, China for mangrove restoration since 1993. However, the effect of Sonneratia plantation on the macrobenthic infaunal community, a vital component of energy flow and nutrient recycling in mangrove ecosystems, remains obscure. The present study aimed to answer this question by determining the macrobenthic infaunal community, habitat characteristics and physico-chemical properties of sediment in the vegetated sites, dominated by different mangrove species (Kandelia obovata, Avicennia marina and S. caseolaris), and un-vegetated mudflat at four sampling times from August 2008 to September 2009. Results showed that the presence of Sonneratia can enhance the biodiversity of macrobenthic infauna in terms of Shannon–Weaver index (H′), compared to the mudflat, since August 2008 onwards. Multivariate analyses (CLUSTER and SIMPER) showed that the macrobenthic infaunal community in the Sonneratia site was different from all the other sites due to higher abundance of deposit and filter feeders, including Limnodriloides sp., Capitella capitata, Potamilla acuminata, Tharyx sp. and Ampharete arctica. The presence of Sonneratia, however, could not significantly alter the sediment properties. Spearman correlation analysis revealed that H′ was negatively correlated with cadmium concentration whereas distance-based linear model (DistLM) suggested that cadmium was a significant predictor variable correlating with the macrobenthic infaunal community. The higher cadmium concentration in August 2008 explained why H′ was lower and different macrobenthic infaunal communities were observed compared to the other sampling times. However, cadmium was the only significant predictor variable explaining 14.9% total variation, suggesting that the macrobenthic infaunal community was generally not affected by the sediment properties. Therefore, we concluded that Sonneratia plantation in the open mudflat can enhance the biodiversity of macrobenthic infauna in view of higher habitat complexity (e.g. presence of pneumatophores, below-ground vegetation and litter) on condition that the cadmium concentration was below the harmful level.

White‐tailed deer (Odocoileus virginianus) positively affect the growth of mature northern red oak (Quercus rubra) trees

Understanding and predicting the effects of deer (Cervidae) on forest ecosystems present significant challenges in ecosystem ecology. Deer herbivory can cause large changes in the biomass and species composition of forest understory plant communities, including early life‐cycle trees (i.e., seedlings and saplings). Such changes can impact juvenile to adult transitions and the future age structure and species composition of mature forests. Changes to understory vegetation also impact flow of energy and nutrients in forest ecosystems. Studies examining the influence of deer on mature trees, however, are rare and rely on extrapolating effects from early life cycle stages of trees. We tested the hypothesis that the absence of deer would result in an increase in the growth rate of mature trees by examining the impact of white‐tailed deer (Odocoileus virginianus) on mature canopy trees. We examined incremental growth in individuals of Quercus rubra, an important component of temperate deciduous forests in North America, inside and outside 16‐year deer exclosures in eastern U.S. deciduous forests. We found that adult trees inside exclosures grew less than those directly exposed to deer. Our findings highlight the indirect effects of white‐tailed deer on the growth of adult individuals of Q. rubra in a way opposite of what would be expected from previous studies based on immature or understory tree populations. We suggest the increased growth of adult trees in the presence of deer may be explained by increased nutrient inputs through deer fecal and urine deposits and the alteration of the competitive environment belowground through the reduction of understory vegetation by browsing. Underscoring the ecological and demographic importance of adult trees in forest ecosystems, results from this study suggest the direct and indirect effects of deer on mature trees should not be overlooked.

Mixotrophy in microorganisms: Ecological and cytophysiological aspects

Mixotrophy is the ability to combine autotrophic and heterotrophic modes of nutrition. It is widely spread in various microorganisms, particularly in such important plankton groups as dinoflagellates and cyanobacteria. Mixotrophy has a significant impact on our comprehension of the matter and energy flows in marine ecosystems, and therefore, it is an object of much attention for several recent decades. Nevertheless, the precise data on the balance of auto- and heterotrophy during the mixotrophic growth have been absent so far, which is due, first of all, to insufficient understanding of physiological and molecular ground of this phenomenon. In this review we discuss some ecological and cytophysiological aspects of investigation of mixotrophy in microorganisms as well as possible reasons for relatively slow progress in this area.

Ethno-ecological Introspection into Bhagawatgeetaa: 2. Principles and Components of the Ecosystem

The discourse in the Geetaa reveals many aspects of Ecology which are amenable with modern science. The ancient Indian thoughts on Ecological factors; Flow of energy in Ecosystem; Nature's hydrological cycle; Ecological niche and Socio-ecological pyramids are discussed in this paper.

Life history, biomass and production of Coronatella rectangula (Branchiopoda, Anomopoda, Chydoridae) from Minas Gerais

Species of Chydoridae provide the main diversity of the Cladocera. These organisms have been the subject of many studies; some dealing with their role in energy flow in aquatic ecosystems, since they inhabit the littoral region of water bodies which undergo the first impacts from anthropic activities. The aim of this study is to increase knowledge about the life cycle of Coronatella rectangula (Sars, 1861), a species found in several water bodies in the state of Minas Gerais, Brazil. The life cycle was determined by the culture of parthenogenetic females under controlled conditions in the laboratory. Experimental cultures were maintained in growth chambers at a constant temperature of 23.6(±0.5)ºC, through a 12 h light/12 h dark photoperiod. The organisms were fed on a suspension of Pseudokirchneriella subcapitata (Chlorophyceae) (10(5) cells.mL-1), and 0.02 mL of a mixed suspension of yeast and fish ration added per organism in equal proportions (1:1). Fifty parthenogenetic females with eggs were isolated and maintained until they produced neonates. Thirty of these neonates that had less than 24 hours were put in polypropylene bottles of 50 mL and kept in a germination chamber. These organisms were observed daily to obtain the parameters of the life cycle. Biomass and secondary production were also calculated. The embryonic development time of the specimens of C. rectangula was 1.68(±0.13) days and the time to reach primipara, was 2.48(±0.45) days. The mean fecundity of C. rectangula was two eggs/female/brood and the total number of eggs produced by the female during its life cycle was 27.8 eggs. During the whole life cycle, specimens of C. rectangula had a maximum of 14 seedlings, with two instars in the juvenile stage. Total biomass for C. rectangula was 36.66 µgDW.m-3(9.83 for the juvenile stage and 26.82 µgDW.m-3 for adults), and secondary production was 12.10 µgDW.m-3.day-1(8.34 µgDW.m-3.day-1 for egg production and 3.76 µgDW.m-3.day-1 for the juvenile stage).

Estimation of biomass from body length and width for tropical rainforest canopy invertebrates

AbstractAccurate estimates of invertebrate biomass are essential for quantifying community structure, food web dynamics and energy flow in terrestrial ecosystems. In this paper, length‐mass and length × width‐mass regressions were carried out for 18 invertebrate taxonomic groups collected from the canopy of an Australian tropical rainforest. In an additional analysis, invertebrates were divided among seven body shape categories based on the ratio of body length to body width (from short and squat to long and thin) in an attempt to develop accurate equations for estimating biomass that can be applied to any taxonomic group in any locality. For most groups, the inclusion of body width to the predictor variable improved the model, confirming that body shape is an important factor in the accuracy of biomass estimations. The most accurate method for estimating invertebrate biomass was the use of taxon‐specific equations, followed by equations based on body shape. Single whole‐fauna equations were very inaccurate for estimating biomass, especially for insects that are either very squat or very long and thin. In accordance with previous studies, it was concluded that the most accurate method for estimating invertebrate biomass from proxy body measurements is the use of taxon‐specific regression equations, especially those that incorporate body width in the model. However, equations based on body shape categories may be useful for estimating the biomass of groups for which no length‐mass relationship has been determined, while single, whole‐fauna equations should be avoided.

Marine fungi may benefit from ocean acidification

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 69:59-67 (2013) - DOI: https://doi.org/10.3354/ame01622 Marine fungi may benefit from ocean acidification Evamaria Krause1,*, Antje Wichels1, Luis Giménez2, Gunnar Gerdts1 1Alfred Wegener Institute for Polar and Marine Research, Biologische Anstalt Helgoland, Kurpromenade 201, 27498 Helgoland, Germany 2School of Ocean Sciences, Bangor University UK, Askew Street, Menai Bridge, Anglesey LL59 5AB, UK *Email: evamaria.krause@awi.de ABSTRACT: Recent studies have discussed the consequences of ocean acidification for bacterial processes and diversity. However, the decomposition of complex substrates in marine environments, a key part of the flow of energy in ecosystems, is largely mediated by marine fungi. Although marine fungi have frequently been reported to prefer low pH levels, this group has been neglected in ocean acidification research. We present the first investigation of direct pH effects on marine fungal abundance and community structure. In microcosm experiments repeated in 2 consecutive years, we incubated natural North Sea water for 4 wk at in situ seawater pH (8.10 and 8.26), pH 7.82 and pH 7.67. Fungal abundance was determined by colony forming unit (cfu) counts, and fungal community structure was investigated by the culture-independent fingerprint method Fungal Automated Ribosomal Intergenic Spacer Analysis (F-ARISA). Furthermore, pH at the study site was determined over a yearly cycle. Fungal cfu were on average 9 times higher at pH 7.82 and 34 times higher at pH 7.67 compared to in situ seawater pH, and we observed fungal community shifts predominantly at pH 7.67. Currently, surface seawater pH at Helgoland Roads remains >8.0 throughout the year; thus we cannot exclude that fungal responses may differ in regions regularly experiencing lower pH values. However, our results suggest that under realistic levels of ocean acidification, marine fungi will reach greater importance in marine biogeochemical cycles. The rise of this group of organisms will affect a variety of biotic interactions in the sea. KEY WORDS: pH reduction · F-ARISA · Helgoland Roads · Microcosms Full text in pdf format PreviousNextCite this article as: Krause E, Wichels A, Giménez L, Gerdts G (2013) Marine fungi may benefit from ocean acidification. Aquat Microb Ecol 69:59-67. https://doi.org/10.3354/ame01622 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 69, No. 1. Online publication date: April 17, 2013 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2013 Inter-Research.

On Diagnostic Index and Method of Healthy Wetland Food Chain

Wetland food chain is the channel of the matter and energy transfer or flow in the wetland ecosystem. From wetland food chain scission mechanism, the structure and functional characteristics of the wetland food chain scission were analyzed, while building a healthy wetland food chain diagnostic index system. Depending on wetland ecosystem health research results, this study brought forward the wetland food chain structure stability and functions of wetland energy measures and their quantitative calculation formula and finally we gave the healthy wetland food chain diagnosis process in order to provide scientific basis for wetland food chain restoration.

庐山森林景观格局变化的长期动态模拟

Forest succession is a naturally occurring process of reorganization which occurs constantly in forest ecosystems; the term refers to the process of one plant community being replaced by another over time. The process of forest vegetation ecological succession is driven by underlying natural conditions and anthropogenic disturbance. We can infer dynamic changes of landscape patterns and corresponding ecological processes of forest succession using forest landscape dynamic analysis based on vegetation patterns. Research related to vegetational succession provides a foundation for the understanding of dynamic changes of forest landscape patterns. The changes of forest landscape pattern also influence nutrient cycling and energy flows in forest ecosystems while restricting a variety of ecological processes. As a result,the study on forest landscape patterns explains very important dynamic processes of forest succession.The natural laboratory of Mount Lushan provides a unique site for studying ecological succession as it relates to vegetation and restoration ecology. The study of forest succession is the foundation of recovery and restoration activities. This type of research depends on the study of ecological succession of vegetation which can provide a basis for understanding the dynamics of landscape change. Using the spatially explicit landscape simulation model( LANDIS),this paper analyzes forest vegetation on Mount Lushan,by stimulating the dynamics of the vegetation's ecological succession in the next 300 aunder undisturbed natural conditions,and determines the representative landscape pattern indices of each patch. This process includes measures of the proportion of the landscape covered by each type of patch area as well as determining the values for the aggregation,fractal dimension,diversity and evenness indices. This process allows the analysis of the spatial distribution pattern of dominant tree species,which helps reveal the factors regulating vegetation succession and helps predict the future trends in variation of the forest landscape. Finally,the theoretical basis for successfully realizing sustainable development of forest resources is discussed. The results indicate:( 1) Over the next 300 a,the extent of a stable populations of broad-leaved tree species will tend to increase; ecological succession in the entire Mount Lushan forest ecosystem is moving in the direction of the reformation of a complex zonal evergreen broad-leaved forest system.( 2) The aggregation index for broad-leaved tree species exhibits a pattern of slow growth in the next 150 a,and then stabilizes after 150 a. The aggregation index of fir remained steady for the entire 300 a while the degree of aggregation for moso bamboo declined steadily throughout the entire simulation until it stabilized during the end stage of the simulation.( 3) The fractal dimension of all dominant tree species is between 1 and 1. 1,illustrating that the edge of each patch is relatively inerratic and experiences small changes during natural forest vegetation succession.( 4) The diversity index of the research region initially tended to increase and later maintained a slow rate of decline. Also,the evenness index initially declined,then rose and went into a slow decline at the end of the simulation. The results of the simulation indicate that the Mount Lushan ecosystem is trending toward an optimal climax community based on the natural forces of ecological succession occurring in the forest community. During this natural ecological succession,various species predominate before the climate evergreen broad-leaved forest stage becomes dominant. In the next 300 years,the reforestation program implemented in the 1960s will not have an obvious influence on climax forest landscape patterns in Mount Lushan. Our research provides a scientific foundation for current and future forest landscape management practices on Mount Lushan. In the long run,we should continue to implement a strict policy of protecting hillside forest habitat to facilitate ongoing afforestation efforts.

Effect of water chemistry on the planktonic communities and relationships among food web components across a freshwater ecotone

Most ecological research on the food web has been focused more on the pelagic zone than on the transitional zone - ecotones between lentic and lotic habitats. The specific goals of this study were to determine whether the contact zone of waters differs in hydrochemical and biological terms from the waters of the canal and the open water zone, and to evaluate the influence of particular macro-habitats on the interactions between components of the planktonic food web. The distribution of samples in ordination space led us to conclude that the studied habitats are distributed along the rising gradient of total organic carbon and nutrients. Assemblages of all investigated groups showed a strong compositional gradient correlated with conductivity and total phosphorus, while a second strong gradient in species composition was explained by nitrate nitrogen and/or phosphate concentrations. The analysis of trophic relationships in the system bacteriaciliates- crustaceans reveals a clear differentiation and strength of mutual relations between the analyzed zones. The highest number of significant correlations was determined in the contact zone. It can also be a place of very efficient matter and energy flow in freshwater ecosystems.

5种温带森林生态系统细根的时间动态及其影响因子

细根(直径≤ 2 mm)的生长和死亡动态及其影响因子是森林生态系统能量流动和物质循环的重要研究内容,但因受到研究方法的限制而了解甚少。于2010年5-10月采用微根管技术对东北东部山区5种温带森林生态系统的细根生长量(FRP)和死亡量(FRM)进行了动态跟踪测定,并同步测定了土壤温度(<em>T</em>s)、土壤湿度(<em>M</em>s)、叶面积指数(LAI)等相关因子。结果表明: 不同林型和取样时间的FRP和FRM均差异显著(<em>P</em> < 0.001)。杨桦林、硬阔叶林、兴安落叶松林、红松林、蒙古栎林的FRP和FRM分别为:(13.34±0.90) μm·cm^-2·d^-1(平均值±标准误)和(5.02±0.36) μm·cm^-2·d^-1、(13.04±0.82) μm·cm^-2·d^-1 和(6.85±0.32) μm·cm^-2·d^-1、(8.74±1.44) μm·cm^-2·d^-1和(5.05±0.61) μm·cm^-2·d^-1、(8.02±2.27) μm·cm^-2·d^-1和(3.88±0.35) μm·cm^-2·d^-1、(7.59±0.82) μm·cm^-2·d^-1和(3.88±0.61) μm·cm^-2·d^-1。所有林型生长季期间FRP的时间变化均呈现明显的单峰型,但峰值出现的时间却因林型而异。FRM随生长季的进程而逐渐增加,杨桦林和硬阔叶林FRM在8月初出现峰值,而红松林、兴安落叶松林和蒙古栎林的FRM峰值均出现在生长季末期。<em>T</em>s、<em>M</em>s和LAI对FRP和FRM均存在显著的正效应(<em>P</em> < 0.05),3个因子的综合作用对各个林型FRP和FRM变异性的解释率分别达68%和53%以上,表明这些温带森林生态系统细根生长和死亡的时间动态主要受土壤温湿度和叶面积变化的联合影响。;Production and mortality of fine roots (diameter ≤ 2mm) and influencing factors are important to energy flow and nutrient cycling in forest ecosystems, but remain poorly understood mainly due to the limitation of methodology. In this study, we used a minirhizotron technique to investigate the temporal dynamics in fine root length production (FRP) and mortality (FRM) of five representative forest ecosystems in Northeast China during the period between May and October of 2010. Soil temperature (<em>T</em>s), soil moisture (<em>M</em>s), and leaf area index(LAI)were simultaneously measured for each stand. The stands were aspen-birch forest dominated by <em>Populus davidiana</em> and <em>Betula platyphylla</em>, hardwood forest dominated by <em>Fraxinus mandshurica</em> and <em>Juglans mandshurica</em>, Mongolian oak forest dominated by<em> Quercus mongolica</em>, Korean pine (<em>Pinus Koraiensis</em>) plantation, and Dahurian larch (<em>Larix gmelinii</em>) plantation. The experimental design included five forest types, three 20 m×30 m replicate plots in each forest type. The results showed that the FRP and FRM were significantly (<em>P</em> < 0.001) affected by forest types, sampling times and their interactions. The FRP was (13.34±0.90) μm·cm^-2·d^-1(mean±SE), (13.04±0.82) μm·cm^-2·d^-1, (8.74±1.14) μm·cm^-2·d^-1, (8.02±2.77) μm·cm^-2·d^-1, and (7.59±0.82) μm·cm^-2·d^-1 for the aspen-birch, hardwood, larch, pine, and oak stands, respectively; and the FRM was (5.02±0.36) μm·cm^-2·d^-1, (6.85±0.32) μm·cm^-2·d^-1, (5.05±0.61) μm·cm^-2·d^-1, (3.88±0.35) μm·cm^-2·d^-1, and (3.88±0.61) μm·cm^-2·d^-1, correspondingly. The FRP showed a unimodal seasonal pattern with peaks varying with forest types. The FRM increased gradually as the growing season proceeded, and reached its maximum at the end of the growing season for all the stands except for the aspen-birch and hardwood stands where it peaked in early August. <em>T</em>s, <em>M</em>s, and LAI all exerted significant positive effects on FRP and FRM (<em>P</em> < 0.05), which, together, explained more than 68% and 53% of variability in FRP and FRM, respectively. These results illustrated that the temporal dynamics of fine root production and mortality in these temperate forest ecosystems were jointly influenced by changes in soil temperature, moisture and leaf area index.

Temporal variation in carbon and nitrogen isotope ratios of aquatic biota in two contrasting boreal streams

Natural abundant isotopes of carbon and nitrogen are frequently used to elucidate food webs and trace energy flows in aquatic ecosystems. Seasonal events such as leaf fall and algal blooms can infl ...

Reconstructing the biogeochemical consequences of disturbances

Paleo Reconstructions of Biogeochemical Environments (PROBE) Workshop;Manhattan, Kansas; 19–21 April 2012 Disturbances—discrete events that reduce plant biomass—commonly regulate material and energy flow in terrestrial ecosystems. Recent studies document an increase in the size and/or severity of disturbances such as native bark beetle outbreaks and large fires compared to the recent past. However, scientists cannot evaluate the potential consequences of these events for ecosystem dynamics without decadal to multimillennial records of disturbances and ecosystem response. The Paleo Reconstructions of Biogeochemical Environments (PROBE) workshop brought together ecosystem ecologists and paleoecologists for a 3‐day workshop at the Konza Prairie Biological Station in Manhattan, Kansas. The focus of the meeting was the reconstruction of the biogeochemical consequences of disturbances (e.g., beetle outbreaks, wildfires, windstorms, and droughts) on different timescales, the assessment of the state of current knowledge, and identification of challenges and opportunities for future research.

Dwarfing of ostracodes during the Paleocene–Eocene Thermal Maximum at DSDP Site 401 (Bay of Biscay, North Atlantic) and its implication for changes in organic carbon cycle in deep-sea benthic ecosystem

The Paleocene–Eocene Thermal Maximum (PETM) has been held up as a past analog to future environmental change and presents the opportunity to study climate impacts on marine communities. During the PETM, deep-sea benthic foraminifers decreased their body-size and increased their productivity, metabolic rates, and food consumption in response to abruptly increasing temperature and changing surface water productivity. Here we find that three species of marine ostracodes – part of the multicellular benthos – also experienced a reduction in body-size in response to PETM warming in the Northeast Atlantic. Positive correlations between ostracode body-size and benthic foraminiferal oxygen isotope data indicate that reduced body-sizes were caused by high temperature during the PETM. Dwarfing of ostracodes during the PETM interval suggests that their food consumption rates, and lifetimes, were less than those of ostracodes in the pre-PETM interval. This interpretation is based upon previous studies that show that food consumption and ostracode lifetimes both decrease as ostracodes increase their growth rates under higher temperatures. Estimates of body volume, temperature, and individual abundance suggest a decline in lifetime metabolic rate in ostracode individuals during the core of the PETM. In addition there is also a decrease in biomass flux in the whole ostracode community at this time. The decline in biomass flux at the community level suggests major changes in the energy flow and carbon cycling in deep-sea benthic ecosystem and the reduction of organic carbon flux between the ostracode community and sediments during the PETM. The decline in ostracode carbon flux stands in contrast with previous interpretations that carbon cycling by benthic foraminifera increased during the PETM. Hence, our data suggest that the benthic community response to the PETM was not uniform between different taxonomic groups.

Ecological Stoichiometry and Multi-element Transfer in a Coastal Ecosystem

Energy (carbon) flows and element cycling are fundamental, interlinked principles explaining ecosystem processes. The element balance in components, interactions and processes in ecosystems (ecological stoichiometry; ES) has been used to study trophic dynamics and element cycling. This study extends ES beyond its usual limits of C, N, and P and examines the distribution and transfer of 48 elements in 16 components of a coastal ecosystem, using empirical and modeling approaches. Major differences in elemental composition were demonstrated between abiotic and biotic compartments and trophic levels due to differences in taxonomy and ecological function. Mass balance modeling for each element, based on carbon fluxes and element:C ratios, was satisfactory for 92.5% of all element–compartment combinations despite the complexity of the ecosystem model. Model imbalances could mostly be explained by ecological processes, such as increased element uptake during the spring algal bloom. Energy flows in ecosystems can thus realistically estimate element transfer in the environment, as modeled uptake is constrained by metabolic rates and elements available. The dataset also allowed us to examine one of the key concepts of ES, homeostasis, for more elements than is normally possible. The relative concentrations of elements in organisms compared to their resources did not provide support for the theory that autotrophs show weak homeostasis and showed that the strength of homeostasis by consumers depends on the type of element (for example, macroelement, trace element). Large-scale, multi-element ecosystem studies are essential to evaluate and advance the framework of ES and the importance of ecological processes.