Re: [ECOLOG-L] Ecohydrology Ratio of water to biomass Re: [ECOLOG-L] Postdoc: Ecohydrology/Plant Water Use, Duke University

[Amartya Saha]

hello Wayne, this is a very interesting question - if i understand you  
correctly, you are enquiring into how much water an individual of a  
species has taken up in its lifetime (to date) and connecting this  
with the total biomass produced to date (including shedded leaves,  
sloughed off roots, fruits, etc).

Now this total biomass over lifetime estimate would be available only  
in a greenhouse setting.  So alternatively you seek to get an estimate  
of total water uptaken and relate that to dry biomass at an instant of  
time.

I imagine there would be a huge amount of intraspecific variation  
caused by the specific conditions of water and nutrients an individual  
may have encountered in its lifetime to date.

In addition, there would also be interspecific variation ( as you  
allude to while comparing cactus and corn), especially when comparing  
species in arid and moist environments, with a larger water to biomass  
ratio expected for aridland vegetation as compared to vegetation  
growing in humid climes.

this could be tied in with species level Water Use Efficiency, I guess.

cheers
amartya







Quoting Wayne Tyson <landr...@cox.net>:

Ecolog:

It depends upon how one defines "water use efficiency," I suppose, but
not in the "production" sense as commonly conceived in the in the case
of agriculture and horticulture, but I wouldn't want to rule those out
either. To put it in contrast, agriculture/horticulture tends to be
more concerned with the amount of production or keeping a plant in a
state of luxury consumption most of the time, whereas "wild"
self-sufficient vegetation is more "concerned" with survival and
reproduction.

To cite a couple of practical phenomena, consider "cattails" (Typha
sp.) growing at the edge of a body of water, and draw a graph, say, at
the top of the plants to indicate one rough measure of biomass; as
water intake declines, biomass declines (setting aside other
effects--O2, pH, nutrients etc.) for the moment). In a cultivated
field, one can observe similar variations due to water intake.

I hope this helps; I apologize for not being clearer--please continue
to ask for further clarification as necessary.

WT


----- Original Message ----- From: "Samuel Pierce (spierce1)"
<spier...@memphis.edu>
To: "Ecological Society of America: grants, jobs, news"
<ECOLOG-L@LISTSERV.UMD.EDU>; "Wayne Tyson" <landr...@cox.net>
Sent: Thursday, August 20, 2009 5:39 AM
Subject: RE: [ECOLOG-L] Ecohydrology Ratio of water to biomass Re:
[ECOLOG-L] Postdoc: Ecohydrology/Plant Water Use, Duke University


Just to clarify, you are asking about water use efficiency?

________________________________________
From: Ecological Society of America: grants, jobs, news
[ecolo...@listserv.umd.edu] On Behalf Of Wayne Tyson [landr...@cox.net]
Sent: Wednesday, August 19, 2009 11:01 PM
To: ECOLOG-L@LISTSERV.UMD.EDU
Subject: Re: [ECOLOG-L] Ecohydrology Ratio of water to biomass Re:
[ECOLOG-L] Postdoc: Ecohydrology/Plant Water Use, Duke University

Ecolog:

Thanks to Adrian for the reference; however, for clarification, I am looking
for the RATIO of biomass to total water intake, not just water content at
any given moment. That is, the total water intake over the entire lifespan
of the plant compared to the dry biomass. For example, a cactus of a given
age would have a high ratio of total water CONTENT to dry biomass, but its
ratio of the total amount of water required to produce a given unit of dry
biomass might or might not be similar to that of, for example, a corn plant
or a redwood tree. My question is aimed at unearthing research of that
kind--or confirming whether or not such research has been done. I don't know
of any--that's why I'm asking.

WT


----- Original Message -----
From: "Adrian Harpold" <aa...@cornell.edu>
To: <ECOLOG-L@LISTSERV.UMD.EDU>
Sent: Wednesday, August 19, 2009 5:31 PM
Subject: Re: [ECOLOG-L] Ecohydrology Ratio of water to biomass Re:
[ECOLOG-L] Postdoc: Ecohydrology/Plant Water Use, Duke University


Wayne,

Check the World's water by Gleick et al.  It has a nice table with
various water contents.

Adrian

On Wed, Aug 19, 2009 at 6:19 PM, Wayne Tyson<landr...@cox.net> wrote:
Ecolog:

I have not kept up to date in this area, but I hope someone will be kind
enough to help me facilitate the necessary work to rectify that, beginning
with answers to the following question:

1. Has anyone studied the ratio of total water intake to biomass exclusive
of water content? (For example, a cactus and a "corn" plant? I would be
most
interested to see graphic comparisons of a diverse and large number of
species. I am curious about the range of differences and the research
methodology.)

WT

PS: I have left the message below attached for reference; it stimulated
the
question, but there is no direct relationship.

----- Original Message ----- From: "Will Cook" <cwc...@duke.edu>
To: <ECOLOG-L@LISTSERV.UMD.EDU>
Sent: Wednesday, August 19, 2009 10:09 AM
Subject: [ECOLOG-L] Postdoc: Ecohydrology/Plant Water Use, Duke University


[For more opportunities, please see the ESA Ecophys section website
http://www.biology.duke.edu/jackson/ecophys/postdoc.htm ]

Postdoctoral Position in Ecohydrology – Plant Water Use

The Biology Department and Nicholas School of the Environment at Duke
University seek a biological or earth system scientist in ecohydrology
and plant water transport. The three-year project, funded by the
National Science Foundation, compares the functioning of deep (5-20
meters underground) and shallow roots and stems for trees growing in the
southern United States. It uses a novel cave system developed by the PIs
in central Texas to study tree roots in situ and is based on previous
molecular-based fingerprinting to match the roots to their respective
shallow counterparts and tree trunks. The research questions include, 1)
How much water that trees use comes from deep underground? 2) What are
the unique physical characteristics of deep roots that promote water
transport? and 3) To what extent do specialized water channels in plants
contribute to their ability to take up and transport water? Primary
responsibilities may include installation and maintenance of sapflow and
microclimate monitoring equipment, periodic collection of plant
physiological and structural data, lab physiological and hydraulic
measurements, and/or modeling of water uptake and transport.

Send a CV, statement of interests, and names of three references to:
jack...@duke.edu or Rob Jackson, Professor, Biology Department and
Nicholas School, Box 90338, French Sciences Building 3311, Duke Univ.,
Durham, NC 27708-0338. Duke is an equal opportunity employer; minority
applicants are strongly encouraged to apply. Applications will be
reviewed as they are received; please apply by September 15, 2009 for
full consideration. Lab web page: http://www.biology.duke.edu/jackson

--
Charles W. (Will) Cook w 919-660-5144
http://www.duke.edu/~cwcook cwc...@duke.edu
Box 90338, Biology Dept., Duke Univ., Durham, NC 27708


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Department of Biology, University of Miami
www.bio.miami.edu/asaha