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Ecophysiology - Science topic

Explore the latest questions and answers in Ecophysiology, and find Ecophysiology experts.
Questions related to Ecophysiology
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Interested in membrane stability index, chlorophyll stability index, specific leaf area/weight.
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I saw in the paper from Nguyen-Queyrens et al. (2002) that osmotic potential = ( osmotic potential at full turgor × 100) / Relative Water Content, but it does not seem correct to just to calculate osmotic potential at full turgor, as (Osmotic Potential × relative water content ) /100. The resulting values are not reliable.
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I would highly appreciate it if my fellow ecologists (biologists) provide their opinion on the thoughts below [esp., shortly tell us which path may be more effective, if they know another way, if there is a recent breakthrough toward this goal].
To consider the effects of Acclimation and Directional Selection on populations' thermal sensitivity in the (mechanistic or phenomenological) modeling of ecological impacts of temperature variability (and climate change), we can follow two general paths:
(1) To produce enough empirical data to define simplistic indices of warm adaptation capacity (based on exposure temperature and duration) for at least some keystone species [a simple e.g., ARR; Morley et al., 2019]. Such indices can only be applied to models' outputs.
(2) To understand the GENERAL mechanisms (principal functional components) defining the heat sensitivity of various taxa [e.g., OCLTT, Pörtner, 2010], define how the component (quantitatively) relates to the capacity for rapid warm adaptation [no Ref.], and set (adaptive) feedback loops in existing models [a simple e.g., Kingsolver et al., 2016].
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Hello Jahangir; You will want to see this paper.
Riddell, et al. 2021. Exposure to climate change drives stability or collapse of desert mammal and bird communities. Science 371(6529); 553, 633-635.
It makes comparisons over a 100 year span of time in the Mojave Desert in California. Thermoregulation!
Best regards, Jim Des Lauriers
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Hi Every one!
I'm Phd student from Cadi Ayyad university/Morocco working on Conservation Biology and Ecophysiology. I need to work with XLSTAT for my research. I worked first wih trial version that finished after 1 months!!
Could someone help me?
Thank you!!
Best regards!!
Soumia,
PhD student/ Cadi Ayyad University
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Moez Kachroud Also I would like download link, please!
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I am trying to make a decision support tool to assess whether, one, two or three years after planting a tree (in my case, in an urban environment), we can consider whether it was successful or not. I am looking for criteria that can be easily used in the field. For the moment, most of the references that I have found relate to tools for rating the state of health of mature trees, generally in a forest environment.
In general, in an urban environment, what do you think are the most reliable criteria to assess the vitality of trees few years after their plantation ?
Do you know of any studies or tools aimed at meeting this need?
Thank you !
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I think the approaches you are looking for could be related to tree architecture studies. So you might be interested in Christophe Drénou's work on the health aspect of trees. The limitation of the method in your case is that it is mostly used in a forestry context on mature trees.
In english (study case on Quercus robur):
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I am working on the BIOME BGC model to simulate the NPP over foothills of Himalaya. How can I do the sensitivity analysis of ecophysiological parameters over my study area?
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Andrew Paul McKenzie Pegman Thanks for the reply. Is there any software to do so?
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The University of Piura is looking for young researchers, post-docs and experienced professors with a strong background in dryland ecosystems. Our goal is to put together a new team for our Research line in Ecology and productivity of dryland forest and present a joint proposal for research funds to the Peruvian government. The current call includes a two years contract to work in Peru with moving expenses included. All interested people can contact Ph.D. Pablo Salazar Zarzosa at pablo.salazar@udep.pe. The research line is described above
Research line: Ecology and productivity of dryland forest
To follow up the scientific projects and research papers carried out in the last three decades, The University of Piura has decided to create a new research line called “Ecology and productivity of dryland forest” focused in the flora and wildlife of the coastal North Peruvian dryland forest. Our goal is to provide an answer to the forestry division, corporations, and rural population in the context of climate change that we are living in. Our research line aims to study (1) the importance of biodiversity in the plant-plant relationships, the species spatial distribution, and forest regeneration. (2) The genetic variability and the biotechnological potential of forest ecotypes for screening processes against diseases and plagues. (3) The climatic variability associated with the El Niño phenomenon (FEN), a global climate event that creates long dry periods interrupted by extreme flood events in this region, and its change in frequency and intensity due to global warming. (4) The productive functions of the forest (wood and non-wood) as the main resource of rural life and industries.
The results of the research line seek to improve knowledge, increase productivity, and reduce vulnerability to climate change of the dryland forest, in order to improve the rural economy of 40 thousand families that rely on it. Our previous studies have focused on fruit production and processing for animal and human consumption. As well as, on forest biomass estimation, ecophysiology, and forest management for sustainable production of timber.
Currently, we are looking forward to studying the causes of Prosopis pallida pathology and the selection of genetic resistance individuals.
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Nice effort
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effect of drought stress on water use efficiency
effect of salinity stress on water use efficiency
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Ecophysiology of Plants is the study of plant processes under the influence of different and particular ecological factors: aridity, salinity, arctic, desertic etc.. However, in many situations, there is no clear delineation between these factors: salinity and aridity are connected in many situations, and - sometimes - flooding conditions may be added.
It is about functional adaptations in plants under different conditions of living.
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Trees don’t grow in deserts (e.g., Sahara). Why? – The answer to this question is based on a particular combination of evolutionary history, physiology and ecology.
Do you agree with this statement?
Could you explain your point of view?
[I’m a Brazilian biologist and writer. I write about science (mainly about population biology) and would like to know the opinion of colleagues from any field of scientific knowledge (and from other countries).]
See also Habitat, environment and ecological niche (https://www.researchgate.net/post/Habitat_environment_and_ecological_niche).
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The relative absence of vegetation in the Sahara is partly due to overgrazing by domestic animals. Have a look at the satellite view of Sidi Toui National Park, Tunisia:
This part of the Sahara is surrounded by a fence, and no domestic animals are let in (but the endemic ungulate Scimitar Oryx is living and grazing here). This part of the Sahara is an arid grassland, scattered with some trees:
Cheers,
Lajos
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I am looking for a fully functional R package for modeling Amax (maximum photosynthesis rate), VCmax (maximum rate of Rubisco carboxylation), Jmax (maximum rate of electron transport for RuBP regeneration) triose phosphate utilization (TPU) limitations and other parameters from gas exchange measurements. This can be an alternative for Photosyn Assistant (http://www.ddsci.com/photosyn.htm). Any supporting comment/answer is highly appreciated.  Thank You.
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Take a look at recent publication
and associated code using R package rjags
Pretty simple set of implementations in a hierarchal Bayesian scheme for fitting multiple curves at once.
Modifying these codes based on updates such as Moualeu-Ngangue et al 2016 would be reasonable.
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I am looking to identify meetings and sessions in the field of xylem/plant water transport. If you have ever organized or attended a conference session or meeting dedicated to any aspect of this area of research please share the name of the conference. Any information is greatly appreciated.
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The next Xylem International meeting will most likely be organized by the University of Padova in Italy i September/October 2019. We are finalizing the organisation right now and I will let you know when I know more.
And yes, Cavitation will be "la part du lion" in this meeting!
Hervé
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Dear Professor Martinez-Garza,
We have installed an experiment of enrichment planting on secondary forest in Central Amazonia near to Manaus, Amazonas. We planted 1,800 seedlings of six important economic species along of a light gradient (understory, intermediate and sunlight) created by thinning treatments. We are monitoring survival, growth and ecophysiological traits since the planting (1 years-old). We intend to monitor at least for more 1 year during the initial establishment. I'd like to ask if you have any interesting to collaborate with us on this study?
With Best Wishes,
Marciel Ferreira
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It will be wonderful to look at some exceptional traits like relative growth rate , flowering intensity with earliness, time of maturity in terms of earliness or lateness etc..
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I have data on african ungulates drinking at different artficial  waterpans at the peak dry time of the system (September-October). I also have data on the surface area and perimeter of these waterpans measured 4 times a year (Jan, April, July and October). My aim is not to go into much detail to describe the pressure but I need to develop a herbivore pressure  index that I will use for something else.
Any help or reference?
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And if you have any meteorological station near the place or in the region, averaged monthly evaporation/sq metre would be also useful to relate to your measured areas.
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There are plenty of estimates on salt marshes, mangroves and seagrass meadows. I am more interested in the contribution of algal forests, such as kelp or fucoides. 
I was able to find estimates by:
S. V. Smith,  1981 - Marine macrophytes as a global carbon sink.
Gattuso et al., 1998 - Carbon and Carbonate Metabolism in Coastal Aquatic Ecosystems
Is there anything more current? 
I also found a book chapter by Middelburg et al, 2005 that has respiration rates only.. 
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Thank you Arvind,
I was not familiar with Frankignoulle & Bouquegneau 1987
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I wanted to study the ecophysiology of J. curcas. So, I am looking for appropriate methodology of studying ecohysiology for example what sorts of climate and morphological data should be measured in the field etc.
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Thanks all for wonderful suggestions especially Dmitry Kutcherov. You are right. Research question is important.
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Hello! I'm conducting a study on the carbon uptake efficiency of the algal genus Kappaphycus. More specifically, how the different environmental factors such as light exposure and salinity affect the RubisCO large-subunit gene (rcbL) which is responsible for carbon fixation. My partner and I are planning to create controlled set-ups with varying levels of light exposure and salinity as independent variables. rcbL gene expression will be measured indirectly through the monitoring of amounts of dissolved inorganic carbon within the set up. Are there any suggestions, comments, or flaws in the setup? Thank you! 
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In the experiment you can try different behavior of radiation wavelengths in the visible spectrum, the near 760 nm, which absorbs the chlorophyll a.The various radiation can be close to 760 nm, for other types of chlorophyll, except chlorophyll a, like except chlorophyll b, c , and a  little farther to other pigments it contains algae (brown pigments, red, etc).
You can also make multi-variant combinations of several factors : different light intensity, different composition of light, different temperatures, different salinity of water.
You can imagine different matrices, keeping one or more constant and telling others.
Good luck in yous work.
Iuliana
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I am particularly interested in the samples processing (Frozen, not frozen, squeezed or intact). Thanks in advance.
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I think you could need a LP-27 Markhart leaf press to extract the liquid sample  directly to a filter paper disc and then  insert the disc into the Wescor C-52 Sample Chamber for the determination of the osmotic potential. That's a secure method that help avoiding some measurement errors. You can see the wescor page in the following link to get the LP.27. And you can see the paper attached as reference. I hope that my answer can be useful. 
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Leaf gas exchange 
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It need to study different formation of gas exchange - for exemple,
pore & papillate epidermal cells of Gingko blob and
after the stomatal diversity.
SEE :Robin Y. Smith a,⁎, David R. Greenwood b, James F. Basinger 
Estimating paleoatmospheric pCO2 during the Early Eocene Climatic Optimum from stomatal frequency of Ginkgo, Okanagan Highlands, British Columbia, Canada
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Dear All, I am looking for a classification  for different "shrub types".There are several terms and definition for shrub, shrublands worldwide.  Some references define shrubs for plants under 5 meter and have branches.  In other side we have half shrubs, cushions like Artemisia. It would be nice to have your advice in definition for shrubs, their possible functional types.
Warm regards, Zahra
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As some scientists have given the definition of shrub, you can check the branching pattern of the shrub and classify them according to the types given below. The shoot systems acquires its character as much if not more from the symmetry and direction of growth of the main axis as from the arrangement of the side branches and their subsidiary branches. If the main axis is vertical it is said to be orthotropous and the plant upright. In this case the radially symmetrical main axis produces its more or less dorsiventral and plagitropous side branches uniformly around the stem. The branching of these side branches either take place on the upper side (epitony) or on the lower side (hypotony) or laterally (amphitony). In shrubs the bud at the lower end or in the middle of the parent axis tend to develop rather than those elsewhere (basitony and mesotony) (Strasburger, English edition 1964)
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Abiotic stress tolerance.
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There are surely certain  nutrient transporters lying embedded in the plasmalemma of root  cells , the density of which decides the accumulation or exclusion behaviour of roots..
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Hello everybody,
In western Algerian Sahara has a forest population of the Argan tree in the north west of Tindouf, it is extremely natural in the wild, and extends over a surface area of more than 50000 hectares, this Saharan ecosystem inhabits a remarkable biodiversity Vegetation and more than 80 taxa and is a habitat for wildlife in a desert environment.
As a result, we will seek international cooperation to target our most vulnerable heritage in the list of protected biosphere areas.
To do this, will you be able to find axes of research to develop it in scientific projects not only ecological, by uncovering the compartment of this tree within these most southern limits.
All my best regards
Kechairi
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No exploitation of argan oil, only some researchers exploit the oil for phytochemical studies and physicochemical properties
in Morocco the argan tree is protected but Dr Reda Keichairi ask about argan tree of Algeria
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It would be my pleasure to have your advice for instruments and facilities in plant ecophysiology lab. We are working  mainly on wild species from rangelands and forests in aridlands.  Some photosynthsis, anzymes and leaf  chemical physiological traits would be favorate parameters. It would be nice if you intrdouce the model of instruments as well.
Warm regards, Negar
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If you want to develop full potential Ecophysiology lab you need following infrastucture
1. Water potential measurement system (Wescor is good)
2. Portable photosynthesis system (Li Cor 6400xt is good)
3. Fluorescence monitoring system (Walz machines are Good)
4. Conductivity bridge for assessing membrane damage etc.
5. If you want assess oxidative damage in plants you need a spectrophotometer
6. Portable leaf area meter etc.
7. LAI measurement systems
Good luck for having adequate funds  because all these equipments are bit costly.
Dr. Annamalainathan
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It is widely accepted that the major factor affecting the evolutionary optimization of animal life histories is energy balance, therefore studies focus on the energy costs and benefits of adaptations, the efficiency of energy acquisition and investment, and limits to energy budgets. However, at the very least in heterotrophs, equally important seems to be the problem of maintaining stoichiometric balance.
There are two approaches in eco-evo studies that consider the matter balance as complementary to the energy balance: ecological stoichiometry and nutritional geometry. However, in my opinion, such studies are limited and after 30 years after Tilman's and Reiners' works (below), still "energocentric" point of view dominates in ecology and evolution, that carelessly underrates the need to balance the diet also in terms of the matter (including the Law of Conservation of Mass).
This is only my point of view, possibly the wrong one. I would like to ask all of you: what is your opinion?
My question was introduced as briefly as possible, don't hesitate to dig deeper and extend it!
Below I present four important studies related to the topic, just to start with.
Kind regards,
Michał Filipiak
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Hi,
The question is how to integrate the stoichiometric concepts into the field data recalculations calculation ? Now field hydrobiologist can use coefficients of tempreture dependend functional indices like respiration or production, and amadements on oxygen concentrtation. But how to calculate disbalance or lack???
Andrey
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i did pcr amplification of lipase gene. but when i tried to repeat the experiment i did not get a band. i checked the dna concentration in nanodrop it is 1000ng/microlitre. i did the reaction in the same conditions of first.
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Thank you for your response
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I am interested to measure PAR under canopy of shrubs. There are some high quality devices (Waltz, adc..) but i would like to have handy field instrument (not very expensive!).
Do you have any advice or experience?
Warm regards,
Mehdi
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Dear Mehdi and Juan Antonio,
Yes, indeed a 1 m bar-type quantum sensor would be the best instrument for measuring PAR in a canopy. Using a small sensor is not impossible, but would require many replicate measurements (in the order of hundreds per location).
What is usually the difference between expensive and cheap quantum sensors?
1) Spectral response: Li-Cor is best with this, you can use Li-Cor sensors under different white light sources with the same calibration and relatively small systematic errors: say less than 10% or so. Cheaper sensors are not really true PAR sensors, they are calibrated as PAR sensors but tend to need recalibration for each different light source. Even some of Apogee's sensors suffer from this problem http://www.apogeeinstruments.co.uk/quantum/ and while Apogee is outspoken about it, other cheap sensors for which makers do not publish the spectral response may be even worse in this respect. For the Spectrum Technology's sensors you can find in their website a manual where the spectral response is plotted, if you compare this curve to that for the "original Apogee" sensor and the true PAR response one can see that the spectral response of this cheaper sensor is really not at all like PAR. However, if the spectral quality of the light is known and the calibration has been done for this same spectral quality, measurements can be almost as good, but you need to take into account that the calibration is strongly light-source dependent. In any case I would not buy any light sensor unless the manufacturer publishes the sensor's spectral response curve as part of the specifications.
2) Cosine correction. Usually only the most expensive sensors get close to the theoretical response as the angle of incidence of light changes. This is especially important, for a horizontal sensor, when solar angles are low, or in any other situation when light is received at a low angle, possibly under a bush in a discontinuous canopy. Again I would not buy any sensor unless the manufacturer specifies the cosine-correction errors.
Other considerations:
a) Buy a sensor that is attached to the meter with a long cable, otherwise you will be unable to avoid your own shade affecting the measurements. Even with a long (2-3 metres) cable make sure to be as low as possible (not standing) and blocking as little of the light as possible. Be also aware that if wearing white or light-coloured clothes you can also increase the readings by acting as a reflector if suitably positioned. The best way to work out what is safe is to rehearse and experiment.
b) For measurements to be reliable and comparable, the sensor needs to be levelled. Li-Cor, Apogee, and most other makers of sensors for field use sell levelling bases with a spirit level. These bases do also play another role: they are heavy enough to keep the sensor where you want while you move some distance away from it to take the readings without causing shading.
c) Temperature stability should be o.k. for most quantum sensors. Weather/water proofing will vary.
Additional thoughts:
1) With care, if you can borrow one of the expensive sensors or a good spectrometer you can calibrate a cheap or even a home-made sensor. This may make sense if you need many sensors.
2) Any sensor should be recalibrated regularly. Calibration of cheap sensors may drift more, requiring more frequent recalibration under continuous field use. Li-Cor sensors are very stable in my experience: recommendation is to recalibrate at least every two years. For Li-Cor sensors this really holds even for continuous measurements in harsh climates. I have no experience with other makes.
3) In addition be aware that the absolute values, and the ratio between above and below canopy irradiance will depend on solar elevation, as well as on how diffuse daylight is. This last point means that measurements on cloudy and sunny conditions, even if expressed as a ratio will not be comparable.
After writing all this, I need to add that in my experience the two most important sources of errors in this type of measurements are: using "subjective" sampling (not well designed protocol for deciding at which points under the canopy to take readings in an objective way), insufficient replication to account for the high spatial heterogeneity and shading (most frequently partial shading by the operator).
Pedro.
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Recent studies (below) showed that predators may need to optimize their diets concerning not only energy but also quality of matter eaten. However, according to common assumption, this is not intuitive (see papers below). What are your thoughts? Is it possible that predators are limited because of macro- or micro- nutrients concentrations in matter eaten? What about elements? Is it possible that for predators important are ratios other than traditional C:N:P, studied using the framework of ecological stoichiometry? What about K and Na? What about Zn:Fe ratio (these two elements compete for absorption sites)?
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Dear Uwe & Michal,
for my opinion you both are right, but important is scale and direct surroundings. Look, for ins. the famous Gause experiments. If you have to do with protists it can be very important what say Michal. Both compounds - I mean behavioral (meanwhile, experience) and physiological "compatibility" of prey present in some proportion for the every predator or semi-predator, but for cheetah experience orientate it when it has choice of victims, but if hungry will no possibility to select.
I saw ciliated infusoria from Dileptus (absolute predators!) genera that eat diatoms algae that should be absolutely inappropriate for it? So, may be as well important is the stage of attack on prey and physiological state of both?
If take into consideration hunting plants - like Nepenthes Rajah (e.g.) from Borneo, the pharmacy of an object is of dominated importance!
The very good explanation of how it works in compact manner gives Wolfgang Meyerhof & Sigrun Korsching in preface of perfect book
Chemosensory Systems in Mammals, Fishes, and Insects. © Springer-Verlag Berlin Heidelberg 2009.
And you can read their opinion of the main scientists in the field (12 person)..
Look attached file.
Andrey
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I am intending to use the  leaf porometer to measure the stomatal conductance for my greenhouse experiment. Can anyone suggest about the accuracy and precision of data obtained from them.
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I´m using a LICOR equipment for mesasuring conductance and assimilation  but exist a good porometer to get a good conductance measuring. Calibration is essential.
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why some plant like pine , snake tree and many more absorb more carbon di.oxide gas than the other.
why normal plant can not absorb high amount while they all are grew approximately in same condition like pines grew in murree where many native specie also grew but they not like wise
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CO2 Consumption and fixation depend upon assimilate sinks, in other words, growth rates, and the actual biomass..... if there is no source depletion the fixation is inhibited..... this in general, fixation of CO2 is also dependent on light, water, and temperatures, which affect Rubisco directly owing to cellular membrane fluidity...  
C4 plants adopted varying CO2 fixation methods, such methods enable C4 plants like sorghum corn, sugar cane and other grasses to fix CO2 concentration at mesophyll close 1 ppm... in other words it can sustain photosynthesis from 330 ppm to 1ppm which takes longer times than C3 which ceases it photosynthesis from 330 ppm dawn to 100 to 70 ppm depends upon varieties. this mean that C4 can continues photosynthesis when their stomata are closed till evening, not like C3 which approaches the compensation point  for a wile after closure ... at evening ..... Drought resistance mechanism.....
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As pointed by Greenfield (1999) and Roulston & Cane (2000), pollen is easily digestible: special adaptations are not needed since pollen grains may be simply destroyed mechanically or through osmotic shock. However there exist a belief that pollen is hardly digestible (mostly because of chemical protection by extracellular wall). Lots of invertebrates belonging to various groups are known to supplement their diets with pollen (even predators). So is pollen easily or hardly digestible? Do you know any papers related to this issue? 
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Dear all,
I would like to mention toxicity of pollen which plays a major role for oligolectic bees; see for example: Praz C.J., Müller A., Dorn S. (2008) Specialized bees fail to develop on non-host pollen: Do plants chemically protect their pollen? Ecology 89, 795–
804.
Klaus
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We research ecophysiology of some alpine plants. We just have soil temperature data at a depth of 10 cm, monitored by data loggers at the site. The air data loggers were taken away by birds or tourists.
We would like to estimate air temperature at 1-5 cm above ground. Is it even possible according to much bigger fluctuations in air temperature?
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Dear colleagues, thank you for your valuable answers.
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Hi everybody, I 'm currently undertaking a study on the ecophysiology of some plant species , in your opinion , what are the best biochemical and molecular parameters that I could aim especially on salt and water stress, thank you for your answers
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I thank you very much for your answers. What about the molecular analysis?
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Neeraj tripathi
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Polyethylene glycol molecules with a molecular weight
larger than 6,000 (PEG 6000) are inert, non-ionic and cell impermeable.
They are small enough to influence the osmotic
pressure, but large enough unabsorbed by plants. Therefore, they are frequently used
to simulate osmotic stress.
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Fish larvae (and mostly also juveniles) are too small to draw blood. Can anyone point me to literature how to assess stress levels in fish larvae not involving RNA/DNA ratios?
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Dear Andrey,
thank you for your reply. Can you please send me a copy of your paper ?
I will then talk to our statistics cracks in the institute.
Best wishes
Andreas
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Can some one send me a practical positive result(s) in ecological restoration that is (are) obtained from the application of AMF. i read some article regarding some good experience in Spain (Barea et al). are there more of such examples? is the role of AMF in ecological restoration a practical one or its just a myth? many thanks in advance.
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The most visible effect of AMF was observed in Coffee, even in areas where the soil is deficit in P and other key nutrients. Enjoy the attached review, though few years old.
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Thanks in advance for your replies.
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Gracias Miquel, esta base de datos se ve muy completa. Voy a ver si me informo del procedimiento para hacerme miembro de TRY.
Un saludo
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Dear colleagues,
I am doing a PhD project studying the ecophysiology of some primitive insects and I am curious in comparison native and invasive species. I would like to look closer at insects community on invasive evening primroses (Oenothera biennis) in Europe and compare them with plants (Oenothera biennis) in the United States. This work will certainly yield an excellent publication and any assistance would be considered an official collaboration with me and would result in an authorship on future manuscripts.
Thank you,
Mima
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Dear Warren, 
Thank you very much. I've already contacted Marc Johnson (it seems promising) but I will also contact Krissa Skogen.
Thanks again :)
Best wishes,
Mima
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We have plans for measuring a number crop ecophysiological properties using three different cameras mounted on a multi-rotor helicopter drone (UAV) - digital RGB, thermal, and multispectral cameras. In addition to a variety of vegetation indices, we would also like to add the capacity of estimating plant height using overlapping images and the on board GPS capabilities. I have done this sort of analysis some time ago with satellite data, but am not currently aware of the open-source options for this analysis.
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If you take multiple images of your area of interest you could use the Structure-from -Motion approach to model the veg in 3D (similar to the link Anupam posted). Just be aware that if you rely solely on the onboard GPS for georeferencing your error bars could be rather large. Two open source SfM softwares are:
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Thanks in advance for your replies.
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I want ot observe all components of behavior, but primary swimming and coactions with the parasites.
Thanks to everyone who answered on the question and happy New Year!
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People who study plant physiology have lots of experience with tree photosynthetical activity thanks to devices like Licor and Waltz.
Most of time, during the working with devices, we input some value (CO2=380, Rh=55%, PAR= 2000  etc.) to the device and we get to output value (A, E, Gs etc.).
So, in vivo and under the natural conditions and outside conditions without input of values, has anybody any experience in measuring photosynthesis parameters ( A, E, Gs, etc.) of forest trees in real-time? 
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It depends what do you know. I had made measurements of gas interchange (with a Li-6400) in mangrove and banana using environmental conditions with good results. However I also made measurements in epiphytic bromeliads in a cloud florest. Here, the problem with 6400 was the high humidy (above 80% all day) which made the stabilization of the equipment slow. But I think that is possible to do good measurements with a gas analyser if you have some patience...
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Not only vultures, ostriches and many other birds that live in hot habitats also have dark feathers. Considering their extremely hot habitat and there are not many objects with such a dark color, why do they have black feathers?
Black colors can absorb sunlight better than other colors so that it can increase body temperature (like in penguins). Besides that, it's hard to camouflage since black color is easily seen in their habitats, which mostly light-brown colored.
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This is actually a pretty old question in thermal biology. Another version of the problem is "why are beetles in the Namib desert black?" Most of the animal physiology textbooks should give substantial insight as a starting point. Withers (1992) "Comparative Animal Physiology" is my usual starting point.
Anyway, the crux of the thing is that black is a pretty good colour in both cold and hot environments, depending on the aim of the game. In the cold it's a very good colour for absorbing heat (hence basking in ectotherms is often facilitated by physiological darkening). The thing is, through, in hot conditions it's a very good colour to dump excess heat. Since black surfaces become so much warmer than the environment heat can easily transfer from the surface by convection or conduction. So the real question you're asking here is what's the evolutionary driver for the vultures in these hot environments? Are they aiming to absorb and retain heat, or are they aiming to dump it? And of course this depends on their altitude, because during high altitude soaring they probably want to retain heat, but at low altitude they probably want to dump it. Hence, for a vulture, black is probably the best colour they could be because they can play both ends off against the middle.
This is, of course, all my general speculation. If you read some general textbooks you should be able to see whether my broad understanding is correct. Also, if you read the paper attached by Dr Blount (and references therein) you'll get a more detailed understanding specific to birds, and of course the whole thing is flexible to the stressors of ecology and evolution, as suggested by Dr. Veroustraete. My caution here is that even a simple question like this often indicates complicated patterns, and that if you get trapped in to narrow a set of assumptions, such as "black is a good colour for cold environments" you can often miss powerful insights.
Anyway, I hope that helps. I've suddenly realised that this reads like a lecture, and I'm probably not qualified to give one. Cheers
Sean
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The standard way we run graduate courses is through a journal club format. I am looking for topic ideas in a field related to Comparative Physiology taking an evolutionary, ecological or conservation physiology approach. Part of my reasoning is to have the course appealing to non-physiologically trained ecologists but also to enhance the broader training of physiologically interested graduate students.
Please post suggestions of topics or research papers.
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Hi Glenn,
A new online journal entitled Conservation Physiology was launched,last year. I suggest to check it out for ideas. We published an invited review in the very first issue of the journal, in which we explore some ideas relevant to your question. It's available here on RG.
Regards,
Hans
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I suppose oxygen isotope enriched water at the upper canopy can diffuse back to lower less enriched leaf by the apoplastic transport, but I don't know whether it is right or wrong.
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Dear Haitao
you might refer in a first instance to the back diffusion of 18O enriched water from the sites of evaporation to the mesophyll itself, which is described by the Péclet effect (radial and longitudinal as described by Farquhar and Gan 2003). If I understand you correctly your point is that this back diffusion could or should also occur from one leaf to another. What we do know is that the water in the phloem sap is 18O enriched compared to the xylem (e.g. Gessler, A., Peuke, A. D., Keitel, C., & Farquhar, G. D. (2007). Oxygen isotope enrichment of organic matter in Ricinus communis during the diel course and as affected by assimilate transport. The New Phytologist, 174(3), 600–613. doi:10.1111/j.1469-8137.2007.02007.x - Fig 4 c; and also some papers of Lukas Cernusak). We also know that newly developing leaves (which do not transpire, yet) are supplied with C via the phloem and thus via the mass flow in the sieve tubes (slightly) enriched water might be transferred to such leaves. This would however be symplastic (phloem) transport and not apoplastic transport and only from transpiring to non-transpiring leaves. Apoplastic diffusion through the petiole and the twig would need to occur against the advective flow in acropetal direction over a real long distance (compared to the back diffusion in the leaf lamina). So I would guess that it is not very likely for mesophyll water of the upper canopy to have a measurable impact on leaves of the lower canopy. What do you think?
Cheers
Arthur
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There has been much recent interest in the role played by oxidative stress as a mediator of the life history trade-off between reproduction and survival. Field studies of birds and mammals have generally shown that oxidative stress is unchanged or increases during reproduction. However laboratory studies on mammals have tended to show completely the opposite: with damage being generally reduced (or unchanged). This has been interpreted as potentially because in the field food supplies are limited, while in the lab food is available in excess. Thus in the field the trade-off becomes exposed. However, a confounding factor is that for various reasons field studies have used blood samples to measure oxidative stress, while the lab, studies have focused on tissue samples.
We have just published 2 papers in two different species (Mongolian gerbils and Brandts voles) (Xu et al 2013; Yang et al 2013) which were both studied in captivity, but from which we sampled both blood and tissues. In both species, using protein carbonylation as the assay, we found the same effect: in blood we replicated the previous field results (greater oxidative damage in reproduction) and in the liver we replicated the previous lab results (lower oxidative damage in reproduction). Plus for several assays the damage was unchanged in both tissues.
I would be really interested in peoples thoughts about these contrasting effects, and what they mean for oxidative stress as a mediator of life history trade-offs. What is likely to be more important: damage in the liver or in the blood? And why? Is there any evidence base on which to make a decision? Should we really be looking at other tissues? And if so which? What about the best assay to use? Is protein damage important? Or is damage to lipids or DNA the thing we should really be paying attention to? And why? Is there any objective evidence on which to make a decision between different damage targets? Based on simultaneous measures of superoxide dismutase it looks like the animals in these 2 studies selectively allocated protection to different tissues: more in the liver and less in the blood? Are some tissues relatively unprotected because oxidative damage to them is less important? What do people speculate is the meaning of these different responses? Where does this leave the idea that oxidative stress is a mediator of life history trade-offs?
References
Xu, Y.C., Yang, D.B., Speakman, J.R. and Wang, D.H. (2013)
Oxidative stress in response to natural and experimentally elevated reproductive effort is
tissue dependent
Functional Ecology
DOI: 10.1111/1365-2435.12168 (online 2nd Oct 2013)
Yang, D.B., Xu, Y.C., Wang, D.H. and Speakman, J.R. (2013)
Effects of reproduction on immuno-suppression and oxidative damage, and hence support or
otherwise for their roles as mechanisms underpinning life history trade-offs, are tissue and assay dependent
Journal of Experimental Biology 216:4242-50.
doi: 10.1242/jeb.092049. (online 30th Aug 2013).
(full text download via JEB web site or via research gate)
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Thanks for posting this Neil. Interesting paper. I'd be interested to know your, and others, views on the severely non-normal distributions of the telomere lengths of different individuals. To me this looks like a small cluster of uncorrelated data, with various outliers dotted around that must completely drive the regressions and estimates of significance, particularly since they used Pearson rather than Spearman correlations. Given the distributions - rank correlations would seem much more appropriate. My guess is that if they had ditched the three outliers with very high RBC telomere lengths instead of just one, all the cross tissue correlations would disappear.
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Leaf structure can affect the leaf water relations such as leaf cell size and cell wall thickness. How do we explain this correlation?
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The ratio Ames/A (mesophyll deconvulted area/ projected leaf area) has been the subject of some issue about gas exchange efficiency. Both PS Nobel and D Parkhurst related this ratio to mesophyll resistance. As the measure of Ames is time consuming and includes stereology and approximations it is advisable to search adaptations within a species by specific leaf area variations. Your question takes a very simple character instead, like the relative lenght of two leaf compartments in trasverse section., but there are behind light density adaptations far more effective than water stress on this ratio. I would well check the mean leaf area in the case, if for example the more spongy ones have larger leaf areas. If cell wall is the thickess is the same the effects could be due to bulk elstic modulus as in Plant Cell Physiol. 2006 Jun;47(6):715-25. Epub 2006 Mar 29.
The bulk elastic modulus and the reversible properties of cell walls in developing Quercus leaves.
Saito T, et alii
but you should better define the relationship in terms of absolute potential and turgor potential after a Pessure Volume Curve and ...
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Vessel elements play a crucial role in the transport of water from roots to leaves.
Fibers are one of the components of sclerenchyma tissue, along with shorter, thick-walled sclereids and associated with the xylem and phloem tissue for support plant.
In the transverse section both are seems same. So what is accurate parameter to differentiation.
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Vessels and fibers in most cases easely be differentiated by cell wall thickness and by the ratio between cell wall and lumen. Also differentate stainig can be used for such search. Also the location of elemets is very important for differetiation of such tissues. It will depend on what plant you study. I think, that you can find more helpful information in 3rd edition of Esau's Anatomy or in similar literature.
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Soil carbon sequestration is perhaps one of the significant functional attributes of below-ground components in an ecosystem, but its quantitative estimation is quite problematic.
To my knowledge, fine roots are good conductors for nutrient foraging and nutrient enrichment in the soil. But in root traits, how much contribution is being made by coarse roots instead of fine roots? What kind of interrelationship takes place with soil carbon sequestration and how do we promote the rate of soil carbon sequestration?
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Dear Ruzhen Wang,
I worked in the Institute of Applied Ecology during 2004-5. I can tell you clear answer, about 10-35 percent carbon is released in the soil through Root exudate, but, nutrient foraging by fine roots for N and P not for carbon. Once a fine root played the role for nutrient foraging then that fine root will die. Therefore, dead fine roots are good source of nutrient as well as carbon for saprotrophs. It is matter of species specific, how much quantity of fine roots biomass producing with respect to life span of a plant. Ideally, photosynthetic output is significantly responsible for fine root production, but if a plant is living in a limited and stressful environment and in addition nutrients (N and P) are limited, in that condition, plant may produce more fine roots stead of structural component like coarse root and stem.
In brief, carbon sequestration in below ground system is not clearly understood, so far I can not say with evidence.
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I would be interested in providing tissues to a lab that has experience imaging or otherwise quantifying mitochondrial density in whole muscle, liver, heart, etc.
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Hi,
You don't actually need to use imaging techniques to measure mt density... One of the easiest way is to measure the citrate synthase with a spec. See this publication: http://onlinelibrary.wiley.com/doi/10.1113/jphysiol.2012.230185/full.
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Do we have enough knowledge of ccm in different clades of algae to predict responses of groups to OA in terms of growth and production of secondary metabolites?
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Hi Andrew, i currently trying to, in part answer, the same question, I writing a chapter for a book on climate change and aquaculture on coastal carbon stocks. So here is my take on the question. First in general, if you dont have it already, the book ocean acidification by Gattuso and Hansson, is a good andlatest general read on those aspects. More specifically your answer by my standpoint has 3 parts, physiological response to a range of independent variable, adaption and the type of adaption that evolutionary fitness criteria imparts. The latter im sure you are familiar with as this was addressed for coccoliths from work down at the MBA in Plymouth. The second, is about the genome variability and the time and possible adaption for selection that meets the ecosystems criteria for success, what ever that may be. The time for selection is mixed for chlamydomonas after 1000 s of generations in a lab experiment found nothing. However, to be fair it needs a population that has been subject to large variations in pH etc. for example upwelling regions. If you have info on this over the longterm, i would be grateful. The first, is the nature of the concentrating mechanism, whether it requires an external proton transferred into the cell producing calcium carbonate outside and extra pCO2 inside or the bicarbonate converted through the usual carbonic anhydrase. Either way, with lower pH comes higher pCO2 and if the light is sufficient, in which it may be lower from increased cloud cover, there is a excess of fixed carbon over nitrogen over its Redfield optimum. Or the lower supply of nitrogen from increased stratification will also produce or add to a highe carbon to nitrogen ratio. In other words autotrophs are plastic in their stochiometry but not consumers. Consequently, and in this way i m using stochiometric theory to predict that higher CN ratios will lead to more detrital proportions and lower consumer production. See Hessen et al reviews on this 2004, a series in Ecology 2004 on sequestration and stochiometry and Hessen and Andersen, 2008 in L&O.
This is what I have gathered for myself so far, if you have any info on upwelling acidification and changes over time on sequestration, i would be very grateful
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In our recent study, we found that the dark respiration of an acroporid coral could be very low in naturally experienced cold water extremes of the Persian Gulf at winter. In this regard, I want to discuss the issue with you.
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thanks a lot, I have not been aware of two of these suggested papers.
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I will only have access to birds stored on fishing boats that have been kept at -20°C. Obviously snap frozen in liquid nitrogen is ideal, but this is unlikely to happen and I will be unable to go to sea myself. So just wondering if anyone has had any experience with this and if so what biochemical data they were able to collect. Seems such a shame to not collect as much information from these birds once killed.
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After the death of birds occurring natural changes of normal parameters. You want to collect blood serum?
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I am conducting a water-relations study on mangrove trees and need a method/instrument to measure the salinity of the soil/pore waters continuously. We have instruments for measuring water relations instantaneously at 10min intervals and would really like to incorporate variation of soil salinity at the same intervals.
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Hi-How far is your water table? actually my response is like a comment than an answer. we have had Institu sensors Aquatrolls 100 measuring salinity in real time of groundwater. Soil salinity is hard to measure continuously. We made a slurry and measured soil salinity in the lab, the thing is there is little water in vadose zone and most sensors measure conductivity of a solution so one has to dilute soil solution and then revert it back to get the native salinity values. Do let me know if you are successful in this quest.
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I'm currently working on ecophysiology of tea ecosystem, in that we are trying to understand the correlation and the impact of climate in crop productivity changes using 20 years meteorological data of the study site using R statistics of VAR package. In order to assess the impact of climate to the 2050 or 2100 scenario I wanted to do Ricardian analysis. I have meteorological, yield and revenue data, kindly give your ideas/comments/ to do the analysis and ideas regarding spatial analysis.
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@ Ahmad
thanks for your commends, we trying to study the three tee growing regions this came under three grids and three different geographic locations. we tring to project the same in spatial models in the we should know the coefficient values that will be used in projection models. I understand the the risk of site specific models however statistical downscalling will help to creat a region specific model upto 24km.
If possible i wll try to get Mr. Kurukulasuriya, in this regards
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I've developed a process-based model for methane emissions from paddy fields, which models the interaction among hydraulic, bio-geochemistry, and plant-root affecting methane production, oxidation and emissions.
In the future, I would like to implement a model able to simulate the effect of methane emission mitigation techniques on plant eco-physiology (e.g. water, temperature, nutrient stresses).
To follow the similar approach of my current model, I would prefer a process-based model instead of classical agronomic ones; i.e. something similar to the soil-plant-atmosphere continuum (SPAC) models for transpiration and photosynthesis.
Unfortunately, a similar model is strongly related to physiology, a topic out of my knowledge to develop it alone.
So, does anyone know if anything similar exists or if it is only a crazy idea? I've made a little literature research without results.
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Hi Senadheera,
first of all, thank you very much for your interesting and your offer of help.
The idea of this topic was to understand if some models similar to what I have in mind alredy exist. In case of positive answer, I could try to persuade my tutors to open this parallel topic, contrarily I've no time in this period to start to build a new branch of the current model.
However,
thanks anyway
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Does anybody know how to convert wind speed measured over a grass surface to the wind speed above the canopy of different aerodynamic parameters (i.e. forest canopy), so that it can be used or calculation of potential evapotranspiration by Penman-Monteith equation?
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Hi Robert,
Thanks a lot. Baldocchi's notes helped.
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Running time of files is up to 24h but can be cut down to any length and file size is 40 Mb to 300 Mb...
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From the look of the signal, it should be easy to approach this problem in any of several different ways. You could load the file into any data analysis environment, detect spikes above a threshold value, time the interval between spikes, and write mean values to a separate data vector or text file. Automating this process is straightforward in almost any advanced data analysis environment. Or you could go the analog route. You can trigger a monostable multivibrator from the spikes, and then integrate the output of the multivibrator using a low pass filter to create an analog voltage proportional to the frequency of the spikes. You can then record that analog voltage with any data acquisition system.
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Has anybody used plant genetics or analysis of phytoliths in this context?
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Speaking particularly to herbivore diet from fecal samples -- phytolith analysis has much to offer. I have looked at far more human paleofeces than herbivore feces, but the principles are the same. For any paleofecal analysis we consider a suite of samples. Pollen, phytolith, and starch analyses comprise a set of microscopic analyses that have been very productive. Each contributes the potential to address different portions of the diet. Pollen and phytoliths are not destroyed in the mouth or anywhere else along the digestive tract. In fact, they are very well preserved in paleofeces. Starches should start their process of digestion in the mouth, so recovering starches can be more problematic. Parasite eggs can be found along with pollen using the appropriate extraction method. Macrofloral analysis also is quite valuable since seeds tend to be very well preserved after traveling through the digestive tract. Some plant cells are preserved, while others simply contribute to the background of unidentifiable remains. I examined paleofeces from Nubia for pollen, phytoliths, parasite eggs (none found in that study -- although I've recovered them in other samples), macrofloral remains, and faunal (animal bone) remains for my dissertation (Cummings, Linda Scott 1989 Coprolites from Medieval Christian Nubia: An Interpretation of Diet and Nutritional Stress. Ph.D. dissertation, Department of Anthropology, University of Colorado, Boulder, Colorado.)