Area Of Ecological Research Research Articles

Modelling density‐dependent fish shoal distributions in the laboratory and field

Density‐dependent variables have long been established as an important area of ecological research, but the effects of the local density of conspecifics on grouping behaviour are less well‐studied. We compared the influence of the density of conspecifics on the shoal size distribution of killifish, Fundulus diaphanus, in the laboratory and the field. In both environments we observed an increase in shoal size and shoal number with the density of individuals present. The increase in shoal size was markedly steeper in the field than in the laboratory, but direct comparison of the two was complicated by the fact that the absolute numbers of fish present at the field site were considerably higher than those used in the laboratory trials. We developed an individual‐based model that was first used as a null model of shoal formation (defined by proximity to others) in fish with no shoaling tendency over the same range of densities used in the laboratory. Group size increased much more rapidly with increasing density in the laboratory than predicted by the null model. When we incorporated shoaling behaviour into our model, the laboratory results could be reproduced with high accuracy. However, when extrapolated to match conditions in the field, the model predicted smaller, more numerous shoals than were actually observed. We suggest this is due to heterogeneity of the field environment because fish were found to be highly aggregated in certain areas of our field site. The predictive power of laboratory studies for the field is discussed with regards to using individual‐based modelling as a tool for deriving such predictions.

Vegetation change: a reunifying concept in plant ecology

Specialization can become detrimental to a discipline if it fosters intellectual isolation. A bibliographic analysis of several research areas in plant ecology (invasion biology, succession ecology, gap/patch dynamics, and global change effects on plants) revealed that plant ecologists do not regularly make use of the findings and insights of very similar studies being conducted in other research subdisciplines, nor do they try to make their findings and insights easily accessible to researchers in other areas. Invasion papers were least likely to be cross-linked (6%) with other fields, whereas gap/patch dynamics papers were most likely to be cross-linked (15%). This tendency toward intellectual isolation may be impeding efforts to achieve more powerful generalizations in ecology by reducing the number of potentially productive exchanges among researchers. In this paper, we illustrate this problem using the example of several speciality areas that study vegetation change. We argue that, rather than characterizing studies of vegetation change on the basis of what distinguishes them from one another, plant ecologists would benefit from concentrating on what such studies have in common. As an example, we propose that several speciality areas of plant ecology could be reunified under the term ecology of vegetation change. Individual researchers, journals, and ecological societies all can take specific steps to increase the useful exchange of ideas and information among research areas. Promoting rapid and more effective communication among diverse researchers may reduce the proliferation of narrow theories, concepts, and terminologies associated with particular research areas. In this way, we can expedite our understanding of the ecological mechanisms and consequences associated with plant communities.

Complexity in Ecology and Conservation: Mathematical, Statistical, and Computational Challenges

Creative approaches at the interface of ecology, statistics, mathematics, informatics, and computational science are essential for improving our understanding of complex ecological systems. For example, new information technologies, including powerful computers, spatially embedded sensor networks, and Semantic Web tools, are emerging as potentially revolutionary tools for studying ecological phenomena. These technologies can play an important role in developing and testing detailed models that describe real-world systems at multiple scales. Key challenges include choosing the appropriate level of model complexity necessary for understanding biological patterns across space and time, and applying this understanding to solve problems in conservation biology and resource management. Meeting these challenges requires novel statistical and mathematical techniques for distinguishing among alternative ecological theories and hypotheses. Examples from a wide array of research areas in population biology and community ecology highlight the importance of fostering synergistic ties across disciplines for current and future research and application.

Mistletoes increasing in ‘undisturbed’ forest: a symptom of forest decline caused by unnatural exclusion of fire?

Summary Increases in populations of mistletoes were observed in undisturbed eucalypt forest near Eden, New South Wales. Repeated counts in an ecological research area showed that there were large increases in mistletoes over 13 years. Populations of mistletoes quadrupled in areas that had few or no prescribed burns. Mistletoes doubled in areas that were patchily burnt by fires of generally low intensity six times in 13 years, but this increase was not statistically significant. Hypotheses advanced to explain the perceived proliferation of mistletoes in rural lands cannot account for the increases in undisturbed forests. However, the results of this study are consistent with a general hypothesis of tree decline in rural lands and forests caused by chronic abiotic stress. Unnatural exclusion of low intensity fire may impair the health of eucalypt forests and cause outbreaks of pests, pathogens and parasites. Populations of mistletoes or other parasites could readily be monitored as indicators of ecological imbalance.

New paradigms for modelling species distributions?

Summary The management of both desirable and undesirable species requires an understanding of the factors determining their distribution. Quantitative distribution models offer simple methods for formulating the species–habitat link and the means not only for predicting where species should occur, but also for understanding the factors involved. Generalized linear modelling, in particular, links the incidence of species to habitat variables, and has increasingly formed the backbone of the modelling approaches used. New ‘data technologies’, such as remote sensing and geographical information systems, have further broadened these modelling applications to almost any ecological system and any species for which there are distribution data. Many previous approaches have aimed to identify the most parsimonious model with the best suite of predictors, selected on the basis of null hypothesis testing. However, information‐theoretic approaches based on Akaike's information criterion allow the selection of a best approximating model or a subset of models from a set of candidates. Information‐theoretic approaches require a deeper understanding of the biology of the system modelled and may well become an improved paradigm for species distribution modelling. Synthesis and applications. This special profile of six papers demonstrates the development in methodology used in species distribution modelling. The papers show how information‐theoretic approaches can be coupled with emerging data technologies to address issues of conservation significance. With conservation biology and applied ecology at the forefront of many of the basic science developments so far, we expect these methods to pervade other areas of ecological research more fully in future.

Global synthesis of leaf area index observations: implications for ecological and remote sensing studies

ABSTRACTAim We present the first global synthesis of plant canopy leaf area index (LAI) measurements from more than 1000 published estimates representing ∼400 unique field sites. LAI is a key variable for regional and global models of biosphere‐atmosphere exchanges of energy, carbon dioxide, water vapour, and other materials.Location The location is global, geographically distributed.Results Biomes with LAI values well represented in the literature included croplands, forests and plantations. Biomes not well represented were deserts, shrublands, tundra and wetlands. Nearly 40% of the records in the database were published in the past 10 years (1991–2000), with a further 20% collected between 1981 and 1990. Mean (± SD) LAI, distributed between 15 biome classes, ranged from 1.3 ± 0.9 for deserts to 8.7 ± 4.3 for tree plantations, with temperate evergreen forests (needleleaf and broadleaf) displaying the highest average LAI (5.1–6.7) among the natural terrestrial vegetation classes. Following a statistical outlier analysis, the global mean (± SD) LAI decreased from 5.2 (4.1) to 4.5 (2.5), with a maximum LAI of 18. Biomes with the highest LAI values were plantations > temperate evergreen forests > wetlands. Those with the lowest LAI values were deserts < grasslands < tundra. Mean LAI values for all biomes did not differ statistically by the methodology employed. Direct and indirect measurement approaches produced similar LAI results. Mean LAI values for all biomes combined decreased significantly in the 1990s, a period of substantially more studies and improved methodologies.Main conclusions Applications of the LAI database span a wide range of ecological, biogeochemical, physical, and climate research areas. The data provide input to terrestrial ecosystem and land‐surface models, for evaluation of global remote sensing products, for comparisons to field studies, and other applications. Example uses of the database for global plant productivity, fractional energy absorption, and remote sensing studies are highlighted.

Niche division and abundance: an evolutionary perspective

AbstractIn recent years, biodiversity has become an issue of broad academic interest, and its assessment and maintenance are now recognized as an important area of ecological research. While the concept of biodiversity encompasses, first and foremost, the total number of species co‐occurring in a locality, it has increasingly been realized that information on the relative abundances of co‐occurring species is also required for a better understanding of the patterns and dynamics of biodiversity. In many areas of ecological research, “abundance” constitutes a key variable that characterizes populations and communities. The relative abundances of species in natural communities reflect evolutionary and contemporary processes occurring on different spatiotemporal scales. The idea of niche apportionment has been developed to provide an integrated conceptual framework for the study of species abundance patterns in communities. This article reviews a number of important issues surrounding the concept of niche apportionment, including some aspects that have received very little or no consideration in previous ecological literature. The main emphasis here is on possible evolutionary implications and backgrounds. Further, as a universal factor which affects species abundance in one way or another, body size is highlighted and its relationship with abundance (“density–body‐size relation”) is considered, referring in particular to a recent comprehensive analysis of freshwater benthic data. Consideration of this and other studies has led to the formulation of the biomass equivalence rule, that suggests the independence of the biomass measure of abundance from body size, which strengthens the logical basis of niche apportionment models. It is suggested that, compared with Hubbell's neutral theory of biodiversity, niche apportionment with the biomass equivalence rule represents a conceptually more sound and widely applicable approach to elucidating species abundance patterns.

Rapid identification of marine algae (Raphidophyceae) using three-primer PCR amplification of nuclear internal transcribed spacer (ITS) regions from fresh and archived material

The internal transcribed spacer region of the nuclear rRNA gene was used to discriminate among the marine raphidophyte species Chattonella antiqua, Chattonella subsalsa, Fibrocapsa japonica, Heterosigma akashiwo, and Olisthodiscus luteus. These microalgae can be difficult to identify from natural water samples, owing to their fragile nature and pleomorphic morphology. Several of these species have been associated with massive fin-fish kills throughout the world, and positive identification is therefore of great economic importance. Species-specific diagnostic polymerase chain reaction (PCR) fragment sizes resulting from three-primer amplification reactions can reproducibly detect as few as five cells per fixed sample and as few as one cell from fresh or frozen samples. Recently, an active area of ecological research has been retrospective studies from archival material to determine population dynamics and species diversity. The PCR primers were successfully used with archived material containing either formalin or Lugol's iodine, as well as with fresh cultures. Because of the existence of other techniques more conducive to monitoring for aquaculture, this assay was developed primarily as a research tool for identification of Raphidophyceae from both cultured and archived field samples where cell integrity has been compromised. It has proved to be a valuable technique for detection and discrimination among marine Raphidophyceae, especially when cells cannot be identified morphologically and fixation methods have destroyed cellular RNA content.

The introduced English wasp Vespula vulgaris (L.) (Hymenoptera: Vespidae) newly recorded invading native forests in Tasmania

AbstractThe social wasp Vespula vulgaris (L.), an introduced species that has caused extreme ecological damage in New Zealand, is reported from southern Tasmanian forests for the first time. In mainland Australia, this wasp has been present in the Melbourne area since 1958 and our retrospective analysis places it in Hobart since 1995. In the present paper, we document V. vulgaris in natural areas in southern Tasmania, well away from human habitation. Malaise trap samples collected since 1997 from nine sites at the Warra Long‐term Ecological Research area in southern Tasmania revealed the widespread presence of both V. vulgaris and V. germanica (F.), another introduced species of concern. Analysis of microsatellite DNA markers showed no evidence of hybridisation between the two species. The potential impact of this newest social insect threat to Australian native biota is discussed.

FORAMINIFERAL ASSEMBLAGES FROM A VIRGINIA SALT MARSH, PHILLIPS CREEK, VIRGINIA

Research Article| April 01, 2000 FORAMINIFERAL ASSEMBLAGES FROM A VIRGINIA SALT MARSH, PHILLIPS CREEK, VIRGINIA Randall S. Spencer Randall S. Spencer Department of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, Virginia 23529 Search for other works by this author on: GSW Google Scholar Author and Article Information Randall S. Spencer Department of Ocean, Earth and Atmospheric Sciences, Old Dominion University, Norfolk, Virginia 23529 Publisher: Cushman Foundation for Foraminiferal Research Received: 06 May 1998 Accepted: 23 Oct 1999 First Online: 03 Mar 2017 Online ISSN: 1943-264X Print ISSN: 0096-1191 © 2000 Journal of Foraminiferal Research Journal of Foraminiferal Research (2000) 30 (2): 143–155. https://doi.org/10.2113/0300143 Article history Received: 06 May 1998 Accepted: 23 Oct 1999 First Online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Randall S. Spencer; FORAMINIFERAL ASSEMBLAGES FROM A VIRGINIA SALT MARSH, PHILLIPS CREEK, VIRGINIA. Journal of Foraminiferal Research 2000;; 30 (2): 143–155. doi: https://doi.org/10.2113/0300143 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyJournal of Foraminiferal Research Search Advanced Search Abstract Phillips Creek is a salt marsh located on the seaward side of the southern Delmarva Peninsula of Virginia, is part of the World Biosphere Reserve designated by the United Nations, and is situated within the Virginia Coast Reserve/Long Term Ecological Research area (VCR/LTER). This marsh does not exhibit well-defined vegetational zones but rather tends to be a patchy mix of vegetation. Cluster analysis indicates that the area can be divided into low, middle or transitional and high marsh. The low marsh zone does not exhibit any unique assemblages of agglutinated foraminifera that would allow further subdivision of this area. The fact that no calcareous species were found may be due to the season (May) when sampling was done. The low marsh is dominated by M. fusca and T. inflata. The occurrence of a transitional or middle marsh zone appears to be dependent upon gradient. Traverse 1 with a gradient of 3 percent has a poorly defined middle marsh zone while Traverse 2 with a gradient of 0.6 percent has a broad, well defined transitional zone. Tiphotrocha comprimata and T. inflata are the dominant species in this zone. The high marsh can be subdivided into two subzones. The lower part of the high marsh is dominated by T. inflata, T. comprimata and J. macrescens while the upper part has a relief ranging between 5 and 8 cm, has a reduced population and contains J. macrescens and T. salsa almost to the exclusion of all other foraminiferal species. This subzone, marking the occurrence of highest high water, is topographically very narrow, requiring closely spaced sampling to detect its presence. The highest high water zone can be extended southward into Virginia. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Ecosystems and Sustainable Development

Review: Ecosystems and Sustainable Development Editors: J.L. Uso, C.A. Brebbia, H. Power Reviewed by Dan Tufford University of South Carolina Uso, J.L., Brebbia, C.A., and Power, H.(editors). Ecosystems and Sustainable Development. Southhampton, UK: Computational Mechanics Publications, 1998. 680 p. US $295 cloth ISBN: 1-85312-502-4. Sustainable development research is a metascience in perhaps the truest sense of the word. Defining, justifying, and implementing sustainable practices transcends not just the basic, social, and applied sciences, but technology as well. Ecosystems and Sustainable Development is a strong volume because it captures this essential nature. The book contains the papers presented at the First International Conference on the subject held in Spain in 1997. The aim of the conference was to encourage and facilitate interdisciplinary communication amongst scientists, engineers, economists and professionals working in the different areas of ecological research. Readers have the opportunity to view a broad sampling of sustainability studies and the issues confronting the global community. The book is organized into three sections. The first is development economics, followed by conservation, management and recovery of endangered and degraded areas, and finally modeling of natural and human ecosystems. In a book with such a broad spectrum of subject material, commenting on specific papers will most likely reflect my own expertise and bias more than it will provide a reasonable critique of the comparative value of specific contributions. With this in mind, it is hoped the more general comments herein will provide more useful guidance to potential readers. Most noticeable is that most of the contributions make little or no mention of sustainability except, perhaps, in the title or introduction. Ideas, research, and results are presented without inter-relating them to sustainability issues or policy recommendations. The reader could just as likely be studying environmental modeling, agricultural economics, or whatever the paper discusses. It is certainly reasonable that those working in the field do not need to explain the connections to their peers, but given the intended audience, contributors could have given more attention to maximizing the potential for interdisciplinary communication. Such is the way of many scientists, however, and for

Primary productivity of the Palmer Long Term Ecological Research Area and the Southern Ocean

A major objective of the Palmer Long Term Ecological Research (Palmer LTER) project is to obtain a comprehensive understanding of the various components of the Antarctic marine ecosystem. Phytoplankton production plays a key role in this so-called high nutrient, low chlorophyll environment, and factors that regulate production include those that control cell growth (light, temperature, and nutrients) and those that control cell accumulation rate and hence population growth (water column stability, grazing, and sinking). Sea ice mediates several of these factors and frequently conditions the water column for a spring bloom which is characterized by a pulse of production restricted in both time and space. This study models the spatial and temporal variability of primary production within the Palmer LTER area west of the Antarctic Peninsula and discusses this production in the context of historical data for the Southern Ocean. Primary production for the Southern Ocean and the Palmer LTER area have been computed using both light-pigment production models [Smith, R.C., Bidigare, R.R., Prézelin, B.B., Baker, K.S., Brooks, J.M., 1987. Optical characterization of primary productivity across a coastal front. Mar. Biol. (96), 575–591; Bidigare, R.R., Smith, R.C., Baker, K.S., Marra, J., 1987. Oceanic primary production estimates from measurements of spectral irradiance and pigment concentrations. Global Biogeochem. Cycles (1), 171–186; Morel, A., Berthon, J.F., 1989. Surface pigments, algal biomass profiles and potential production of the euphotic layer—relationships reinvestigated in view of remote-sensing applications. Limnol. Oceanogr. (34), 1545–1562] and an ice edge production model [Nelson, D.M., Smith, W.O., 1986. Phytoplankton bloom dynamics of the western Ross Sea ice edge: II. Mesoscale cycling of nitrogen and silicon. Deep-Sea Res. (33), 1389–1412; Wilson, D.L., Smith, W.O., Nelson, D.M., 1986. Phytoplankton bloom dynamics of the Western Ross Sea ice edge: I. primary productivity and species-specific production. Deep-Sea Res., 33, 1375–1387; Smith, W.O., Nelson, D.M., 1986. Importance of ice edge phytoplankton production in the Southern Ocean. BioScience (36), 251–257]. Chlorophyll concentrations, total photosynthetically available radiation (PAR) and sea ice concentrations were derived from satellite data. These same parameters, in addition to hydrodynamic conditions, have also been determined from shipboard and Palmer Station observations during the LTER program. Model results are compared, sensitivity studies evaluated, and productivity of the Palmer LTER region is discussed in terms of its space time distribution, seasonal and interannual variability, and overall contribution to the marine ecology of the Southern Ocean.

News: Canadian ecological research area faces major funding cuts

ADVERTISEMENT RETURN TO ISSUEPREVNewsNEXTNews: Canadian ecological research area faces major funding cuts Science Rebecca RennerCite this: Environ. Sci. Technol. 1996, 30, 7, 283APublication Date (Web):June 7, 2011Publication History Published online7 June 2011Published inissue 1 June 1996https://doi.org/10.1021/es962305cRIGHTS & PERMISSIONSArticle Views12Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (3 MB) Get e-Alerts Get e-Alerts

Stability analysis of a nonhomogeneous Markovian landscape model

Quantitative methods to analyze spatial patterns of landscapes are an important area of research in landscape ecology. Nonhomogeneous Markov models can be used to represent landscape dynamics; however, methods to analyze the stability of these models are needed. A method for determining the stability is developed in this paper, and its application to a model of vegetation dynamics in southern Texas savanna is also given. Using Lyapunov stability theory, the theorem that the family of these transition matrices will be stable if the symmetric matrices associated with the vertex matrices have matrix measures less than two has been proved. The results of the stability analysis accord well with current understanding of vegetation dynamics in the southern Texas landscape.

Imaging spectrometry

A basic aim of remote sensing is to identify and characterize objects on the Earth's surface by means of radiation that has interacted with that surface. In the optical region of the spectrum this could best be achieved using an imaging spectrometer that records a finely sampled and continuous spectrum of radiation over the entire 400 nm to 2400 nm wavelength range. This article outlines the airborne imaging spectrometers of today and the space-borne imaging spectrometers of tomorrow, the techniques for processing data from imaging spectrometers and the roles that imaging spectrometry is finding in those areas of geological, aquatic, ecological and atmospheric research which are of interest to physical geographers.

On Characterizing Foraging Versatility, Illustrated by Using Birds

Versatility in foraging behavior is a crucial component of several areas of behavioral and ecological research, including optimal foraging, ecomorphological studies, resource partitioning, and comparisons of guild structures. Unfortunately, the methods by which foraging versatility has been characterized in the past (e.g., Shannon-Wiener and inverse Simpson diversity indices) produce inconsistent results depending upon the degree to which workers split or lump categories of foraging manoeuvres. I refer to this problem as aliasing, by analogy to a similar difficulty that arises in signal processing in electrical engineering (...) A method is presented here to afford some protection against aliasing by using a new versatility index that explicitly accounts for dissimilarities between foraging classes

Effects of Root Plowing on White-Tailed Deer Condition, Population Status, and Diet

Determining the effects of plant community changes on animal populations is an important area of ecological research. We compared condition, population characteristics, and diet composition of white-tailed deer (Odocoileus virginianus) from 2 root-plowed (low brush diversity) and 2 untreated (high brush diversity) sites in the eastern Rio Grande Plains of Texas to test the hypothesis that root plowing, which decreases woody species diversity-, reduced deer habitat quality. We collected 8 adult female white-tailed deer from each site every 3 months for 6 sampling periods. We assessed condition from several physiological, reproductive, and digestive indices and determined food habits by microhistological analysis of rumen samples. We estimated population size from helicopter surveys

Mapping a Long-Term Ecological Research Area in Puerto Rico

Mapping a Long-Term Ecological Research Area in Puerto Rico

Methane consumption and emission by Taiga

Taiga or boreal forest environments are a poorly understood component of the global CH4 budget. Results from a 1‐year study of CH4 fluxes at a range of representative floodplain and upland taiga sites in the Bonanza Creek long term ecological research area show that soil consumption of atmospheric CH4 was the dominant process. Methane emission occurred only sporadically in the earliest successional stages in the floodplain system; all other floodplain and upland sites were net CH4 consumers. Our results suggest that upland and floodplain taiga soils are an atmospheric CH4 sink of up to 0.8 Tg yr−1. Point‐source bogs and fens are the only important CH4‐emitting sites in taiga.

Non-consumptive wildlife-oriented recreation: A conceptual framework

Recreational non-consumptive use of wildlife has been attracting increasing numbers of people and generating growing economic benefits from tourism activity. More importantly this type of wildlife interaction has potential benefits to conservation from the long-term effect of changing attitudes towards wild animals and natural habitats. It does not, however, fit well into the existing wildlife management paradigm due to the nature of the final product, a recreation experience. This paper aims to provide an integrated framework that illustrates the major components of non-consumptive wildlife recreation and links between research areas in ecology, animal behaviour, recreation, tourism and existing wildlife management institutions. The fundamental purpose of this paper is to cast wildlife conservation in a new light that recognizes the need to formulate management plans in both a social and biological context.