Population, Community, Ecosystem, Conservation, Resource Management.

• Christian Roschak

  Sampling method to investigate regeneration success of rare tree species

  I want to investigate regeneration success of light-demanding gymnosperm tree species in a mixed gymnosperm-angiosperm forest half a century after uncontrolled high-impact logging. All merchantableI want to investigate regeneration success of light-demanding gymnosperm tree species in a mixed gymnosperm-angiosperm forest half a century after uncontrolled high-impact logging. All merchantable gymnosperms were harvested at that time. Today, regenerated gymnosperms are very rare in this forest and are found mainly in small clusters. What sampling methods are appropriate to investigate why gymnosperms successfully regenerated on some sites while they did not on others? I’m mainly interested in factors that explain why those gymnosperms are present at certain locations. As I believe that the intensity of logging (disturbance, gap size, size and species of residual trees) has a major influence on today’s structure in that forest, I want to compare the forest structure at sites where gymnosperm regeneration was successful to sites where it wasn’t. From my first observations, the gymnosperms are today mainly found where the angiosperm trees (shade-tolerant) were clearfelled. Wherever angiosperm trees were left, gymnosperm regeneration was shaded out or overgrown by angiosperm regeneration in the past decades. The problem: When I use random sampling, I barely hit any clusters of gymnosperm trees and need an inappropriate large number of sampling plots. Even when I use transects, I don’t hit enough clusters and end up with many kilometres of transect lines. Therefore, I thought about subjectively searching for those clusters in the forest and then investigating the forest structure at those sites. Then I want to compare these recorded structures with the structures of randomly selected sites (regardless if the gymnosperms are present at those sites or not). With that I hope to be able to relate the intensity of disturbance to regeneration success of the gymnosperm tree species. Does this make sense and is it possible to analyse the data with statistical methods? Subjective searching for those gymnosperm clusters worries me most here … Thank you for your answers

  Recent replies ⋅ Show All (18)

  • 
    Manuel Weinkauf replied

    I think under the given circumstances it heavily depends on what exactly you want to investigate. Are you simply interested in a variety of abiotic factors that differ between sites were gymnospermsI think under the given circumstances it heavily depends on what exactly you want to investigate. Are you simply interested in a variety of abiotic factors that differ between sites were gymnosperms recovered and sites where they did not, such as nutrition level in the soil, lighting, and so on. Under those circumstances I would think that your satellite approach is 'random enough' to lead to reasonable results. Even better, it may be quite good to compare plots were there are no gymnosperms with closest satellite plots with gymnosperms. This would fall somehow in the range of the randomised block design of a mensurative experiment, and having lots of such two-plot-pairs ensures a large enough number of replicates to draw reasonable conclusions. If you also want to include biotic factors, such as competition, I am not absolutely sure whether or not samples would be sufficiently random. After all you could use some measurement as indicator for competition. If you have chosen a particular gymnosperm you could measure the distance to and species of the closest angiosperm, for instance. But for that you need lots of gymnosperms chosen in a statistical useful manner. It may work in the way you want to work, and I would at least give it a try, but possibly a systematical sampling approach would indeed be better in that case. You would have to assure, however, that logging did not occur in some kind of spatial pattern that still prevails in the forest pattern today, because then you could force a pre-existing pattern to corrupt your sampling data. As a side remark, since you seemingly have satellite images available, do you have access to not-VIS channels of those images. As far as I remember angiosperms and gymnosperms can be distinguished by their colour in composite images of certain IR-UV channels, as e.g. LANDSAT is providing them.

    58 minutes ago
• Ian Smith

  What are some good methods for determining indicator species and vegetation characteristics?

  I am researching the influence of shelterbelts (hedgerows/windbreaks) characteristics and resources on beneficial and pest arthropod species. I have measured about 60 variables about the features ofI am researching the influence of shelterbelts (hedgerows/windbreaks) characteristics and resources on beneficial and pest arthropod species. I have measured about 60 variables about the features of the shelterbelts and have just finished counting the first months worth of insect captures, sorting them into about 70 groups (not all of these are likely to be useful). It will take too long to finish counting all the insect collections as intensively as the first month's count so I'm trying to work out how I can whittle down the number of arthropod families to a few indicator species and determine which vegetation features are most notable. Anyone have any ideas or tips on how to achieve this?
• Robin Gras

  Follow the a weekly report of virtual evolving ecosystem’s very long run We study the evolutionary process and the emergence of species in a simulated ecosystem. We have conceived EcoSim, anFollow the a weekly report of virtual evolving ecosystem’s very long run We study the evolutionary process and the emergence of species in a simulated ecosystem. We have conceived EcoSim, an individual-based evolving predator-prey ecosystem simulation. The agents evaluate their environment (e.g., distance to predator/prey, distance to potential breeding partner, distance to food, energy level), its internal state (e.g., fear, hunger, curiosity) and chooses among several possible actions such as evasion, eating or breeding. The behavioral model of each individual is unique and is the outcome of the evolution process. This is the only simulation modeling the fact that individual behaviors affect evolution and speciation. We were able to predict species extinction using information about spatial distribution of the individuals, to correlated genetic diversity with the fitness of a species, to show that the overall behaviour of our simulation is deterministic chaotic with multifractal properties and to predict speciation events using some features describing the species properties. This approach will be also used to study the species abundance distribution, patterns and rates of speciation, the evolution of sexual and asexual populations, the interaction and diffusion of an invasive species or a disease in an existing ecosystem, etc. We propose a weekly presentation of a run of our simulation that will last for tenth of thousand of time steps at this site: http://sites.google.com/site/ecosimgroup/research/ecosystem-simulation/long-run. Every week we will add a page presenting a detailed summary of what happen in the system during the last 500 or 1000 time steps. We will show many graphs, videos and figures presenting the evolution of the system, including the number of individuals, the number of species, the amount of food available, the tree of life of the world, the distribution of age of the individuals, the evolved behavioral maps of some individuals, the variability of the gene alleles in the populations… This will allow following the ongoing evolutionary process and its effects on the whole world for thousand of generations.
• Deepu Sivadas

  What is ecological niche modelling?

  What are the differences between correlative and mechanistic models? What are the observations required for niche modelling and the programms except DIVA GIS used for this purpose?

  Recent replies ⋅ Show All (6)

  • 
    María Napal replied

    The distinction between correlative and mechanistic models: Buckley et al. Ecology Letters, (2010) 13: 1041–1054

    Apr 20, 2012
• Lucy Alice Hawkes

  Considering the 'Tragedy of the Reviewer Commons' would you forward reviews of a rejected paper with a submission to another journal? Who owns them?

  For more information about the challenges of using reviewer effort wisely, see: Hochberg et al. (2009) EcolLett: http://onlinelibrary.wiley.com/doi/10.1111/j.1461-0248.2008.01276.x/abstract and alsoFor more information about the challenges of using reviewer effort wisely, see: Hochberg et al. (2009) EcolLett: http://onlinelibrary.wiley.com/doi/10.1111/j.1461-0248.2008.01276.x/abstract and also Rohr & Martin (2012) TREE: http://www.cell.com/­trends/ecology-evolu­tion/fulltext/S0169-­5347%2812%2900031-6 Who owns the reviews submitted for your manuscript?

  http://www.cell.com/trends/ecology-evolution/fulltext/S0169-5347%2812%2900031-6
• Kani Mophin

  Do any of you know stream functioning and modelling well?

  I hope mathematical modelling may helps in understanding the functioning continuum of the river please help on this things

  Recent replies ⋅ Show All (3)

  • 
    Laura Puértolas replied

    There are many aspects of stream functioning that may be explained through a mathematical model. Of course if you want to understand the River continuum concept efectively you may look in theThere are many aspects of stream functioning that may be explained through a mathematical model. Of course if you want to understand the River continuum concept efectively you may look in the original Vannote's paper. If you want to get a broader idea of stream processess you may also start with a more general reference. There is a lot of bibliography but in my opinion "Stream Ecology: Structure and function of running waters" from Prof. J.D. Allan would be a nice starting point. There you may also find an updated explanation of the RCC. Best regards ;)

    Apr 16, 2012
• Anna Wilczek

  High trees needed

  I am looking for info about species of highest trees, mostly in emergent layer of tropical rain forest, but everything about this will be appreciated.

  Recent replies ⋅ Show All (3)

  • 
    Kristian Slavov replied

    "William F. Laurance, an ecologist at James Cook University in Cairns, Australia, provides evidence of decline among the world's "biggest and most magnificent" trees and details the range of threats"William F. Laurance, an ecologist at James Cook University in Cairns, Australia, provides evidence of decline among the world's "biggest and most magnificent" trees and details the range of threats they face. He says their demise will have substantial impacts on biodiversity and forest ecology, while worsening climate change. He added: "To persist, big trees need a safe place to live and long periods of stability," he told mongabay.com via email. "But time and stability are becoming very rare commodities in our modern world."

    http://news.mongabay.com/2012/0126-big_trees.html

    Jan 27, 2012
• Francisco Fajardo Gutiérrez

  Short course of ecological retoration, Nariño Colombia.

  203_Cartilla_RESTAURACION_ECOLOGICA_2009.pdf

  Recent replies ⋅ Show All (2)

  • 
    Francisco Fajardo Gutiérrez replied

    Hello, unfortunatly we dont have an english version, may be you can use an internet translater...

    Jan 23, 2012
• Francisco Fajardo Gutiérrez

  Recent works on plant-animal interactions, Mariquita Colombia.

  Compendio curso Interac. planta-animal 2.pdf

  Recent replies ⋅ Show All (1)

  • 

    Comment protected

    Join ResearchGate now to read this comment.