Go to OSU College of Forestry LWGate Home Page.From: "Dries Vansteenkiste" <Dries.Vansteenkiste@UGent.be>
Subject: Re: [IAWA Forum] More questions on Circulation within a tree.
Date: Fri, 2 Jun 2006 15:59:34 +0200
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This is a multi-part message in MIME format. ------=_NextPart_000_013D_01C6865D.8B0D4120 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I'm not familiar with Strasburger's experiment, but couldn't it be = possible that 1. sap conduits (mainly vessels in broadleaved trees) = remained intact after cutting off the (submerged?) roots, 2. that the = leaves simply continued transpiring (or evaporating) stored water from = within the "living" part (sapwood) of the tree body (much like cut = flowers in a bowl of water), hence still pulling up sap as a result of = the water potential gradient, and 3. that the ascent of the acid = progressively killed the cells lining or in contact with the vessels, = the sap and acid ultimately reaching the green parts of the tree making = them die subsequently from dessiccation and acidolysis? I could imagine a tree staying "alive" or at least transpiring this way = for three weeks... Furthermore, I don't see how 98% concentrated sap could flow back or = down from leaves to branches or to stems... Wouldn't this occur in phloem rather than in xylem, i.e. like in the = living tree? Dries Vansteenkiste Laboratory of Wood Technology Faculty of Bioscience Engineering (FBE) University of Ghent Coupure Links 653 9000 Gent Belgium ----- Original Message -----=20 From: Andrew K Fletcher=20 To: iawa@COF.ORST.EDU=20 Sent: Friday, June 02, 2006 2:15 PM Subject: [IAWA Forum] More questions on Circulation within a tree. A while ago, the question of density changes in residual leaf and = branch fluids as a direct result of the efficient transpiration from the = leaves of a tree was put to the group. Judging from the responses which = were also posted at the request of one of the groups members, it would = be fair to deduce that there is a general acceptance that density = changes would be an inevitable consequence of the evaporation of 98% of = the water from the leaves. several members also began to question what would happen to the sap = once the density had increased and indeed it was suggested that it would = be acted upon by gravity and that the sap would be moved as a result of = this interaction with gravity. This brings me to the next part of this important question for the = group. Explaining the results of Eduard Strasburger's experiment Andrew K Fletcher Evaporation from the leaves alters the density of the sap at the leaf, = and gravity pulls the denser sap down. This generates a positive = pressure in front of the falling sap, and a tension / negative pressure = behind the falling sap, which initiates a simple flow and return, much = the same as found in a simple flow and return domestic central heating = system, where the heat from the boiler alters the density of the water = causing the heated water to rise, where it is cooled inside the hot = water tank via a coiled copper tube, returning the cooled water back to = the boiler.=20 The German botanist Eduard Strasburger's famous experiment - where he = killed all of the cells in a tree by cutting off the roots, while = submerged in a bath of picric acid - demonstrated that transpiration and = circulation was maintained for three weeks, after the death of the tree. I put it to the group that either the picric acid or the copper = sulphate solution used by Strasburger, caused the minerals and sugars = held within the dying leaves and branches to be released over the 2 = weeks and that this was all that would be required for a simple flow and = return system to maintain the circulation and transpiration. = Furthermore, the experiment does suggest that no living process need be = involved in the bulk flow of a tree. This would result in a downward flow caused by the liberated solutes = and this would in turn generated suction at the base of the tree = sufficient to draw in more dilute solution from the bath, and that this = flow would continue until the liberated salts and sugars had either all = reached the picric acid / copper sulphate bath, or that the liberated = salts and sugars had changed the density of the fluid within the tub to = counterbalance any falling solutes. Andrew K Fletcher, UK=20 ------=_NextPart_000_013D_01C6865D.8B0D4120 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=3DContent-Type content=3D"text/html; = charset=3Diso-8859-1"> <META content=3D"MSHTML 6.00.2900.2873" name=3DGENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=3D#ffffff> <DIV><FONT face=3DArial size=3D2>I'm not familiar with Strasburger's = experiment, but=20 c</FONT><FONT face=3DArial size=3D2>ouldn't it be possible that 1. sap = conduits=20 (mainly vessels in broadleaved trees) remained intact after cutting off = the=20 (submerged?) roots, 2. that the leaves simply continued transpiring = (or=20 evaporating) stored water from within the "living" part (sapwood) of the = tree=20 body (much like cut flowers in a bowl of water), hence still = pulling up sap=20 as a result of the water potential gradient, and 3. that the ascent of = the acid=20 progressively killed the cells lining or in contact with the vessels, = the sap=20 and acid ultimately reaching the green parts of the tree making them die = subsequently from dessiccation and acidolysis?</FONT></DIV> <DIV><FONT face=3DArial size=3D2>I could imagine a tree staying "alive" = or at=20 least transpiring this way for three weeks...</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Furthermore, I don't see how 98% = concentrated sap=20 could flow back or down from leaves to branches or to = stems...</FONT></DIV> <DIV><FONT face=3DArial size=3D2>Wouldn't this occur in phloem rather = than in xylem,=20 i.e. like in the living tree?</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Dries Vansteenkiste<BR>Laboratory of = Wood=20 Technology<BR>Faculty of Bioscience Engineering (FBE)<BR>University of=20 Ghent<BR>Coupure Links 653<BR>9000 Gent<BR>Belgium</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV>----- Original Message ----- </DIV> <BLOCKQUOTE dir=3Dltr=20 style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; = BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> <DIV=20 style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: = black"><B>From:</B>=20 <A title=3DGravity@blueyonder.co.uk=20 href=3D"mailto:Gravity@blueyonder.co.uk">Andrew K Fletcher</A> </DIV> <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A = title=3Diawa@COF.ORST.EDU=20 href=3D"mailto:iawa@COF.ORST.EDU">iawa@COF.ORST.EDU</A> </DIV> <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Friday, June 02, 2006 = 2:15 PM</DIV> <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> [IAWA Forum] More = questions on=20 Circulation within a tree.</DIV> <DIV><BR></DIV> <DIV><FONT face=3DArial size=3D2><FONT size=3D3><FONT face=3D"Times = New Roman"><SPAN=20 class=3DsurveyDebateDate></SPAN></FONT></FONT></FONT><FONT = face=3DArial=20 size=3D2><FONT size=3D3><FONT face=3DArial size=3D2><SPAN=20 class=3DsurveyDebateDate></SPAN></FONT></FONT></FONT> </DIV> <DIV><FONT face=3DArial size=3D2><FONT size=3D3><FONT face=3D"Times = New Roman"><SPAN=20 class=3DsurveyDebateDate><FONT face=3DArial><FONT size=3D2>A while = ago, the question=20 of density changes in residual leaf and branch fluids as a direct = result of=20 the efficient transpiration from the leaves of a tree was put to the = group.=20 Judging from the responses which were also posted at the request of = one of the=20 groups members, it would be fair to deduce that there is a general = acceptance=20 that density changes would be an inevitable consequence of the = evaporation of=20 98% of the water from the=20 leaves.</FONT></FONT></SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=3DArial size=3D2><FONT size=3D3><FONT face=3DArial = size=3D2><SPAN=20 class=3DsurveyDebateDate></SPAN></FONT></FONT></FONT> </DIV> <DIV><FONT face=3DArial size=3D2><FONT size=3D3><FONT face=3DArial = size=3D2><SPAN=20 class=3DsurveyDebateDate>several members also began to question what = would=20 happen to the sap once the density had increased and indeed it was = suggested=20 that it would be acted upon by gravity and that the sap would be moved = as a=20 result of this interaction with = gravity.</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=3DArial size=3D2><FONT size=3D3><FONT face=3DArial = size=3D2><SPAN=20 class=3DsurveyDebateDate></SPAN></FONT></FONT></FONT> </DIV> <DIV><FONT face=3DArial size=3D2><FONT size=3D3><FONT face=3DArial = size=3D2><SPAN=20 class=3DsurveyDebateDate>This brings me to the next part of this = important=20 question for the group.</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=3DArial size=3D2><FONT size=3D3><FONT face=3D"Times = New Roman"><SPAN=20 class=3DsurveyDebateDate><FONT face=3DArial><FONT=20 size=3D2></FONT></FONT></SPAN></FONT></FONT></FONT> </DIV> <DIV><FONT face=3DArial size=3D2><FONT size=3D3><FONT face=3D"Times = New Roman"><SPAN=20 class=3DIndexAlphabeticalTitle><B>Explaining the results of Eduard = Strasburger's=20 experiment</B></SPAN><BR class=3DNetscapeDummy><SPAN=20 class=3DIndexAlphabeticalAuthor>Andrew K Fletcher</SPAN><BR=20 class=3DNetscapeDummy></FONT></FONT><SPAN class=3Dbodyp>Evaporation = from the=20 leaves alters the density of the sap at the leaf, and gravity pulls = the denser=20 sap down. This generates a positive pressure in front of the falling = sap, and=20 a tension / negative pressure behind the falling sap, = which initiates a=20 simple flow and return, much the same as found in a simple flow and = return=20 domestic central heating system, where the heat from the boiler = alters=20 the density of the water causing the heated water to rise, where it is = cooled=20 inside the hot water tank via a coiled copper tube, returning the = cooled water=20 back to the boiler. </SPAN></DIV> <P><SPAN class=3Dbodyp>The </SPAN><SPAN class=3Dbodyp>German = botanist Eduard=20 Strasburger's famous experiment - where he killed all of the cells in = a tree=20 by cutting off the roots, while submerged in a bath of picric acid -=20 demonstrated that transpiration and circulation was maintained for = three=20 weeks, after the death of the tree.</SPAN></P> <P><SPAN class=3Dbodyp>I put it to the group that either the picric = acid or the=20 copper sulphate solution used by Strasburger, caused the minerals and = sugars=20 held within the dying leaves and branches to be released over the 2 = weeks and=20 that this was all that would be required for a simple flow and = return=20 system to maintain the circulation and transpiration. Furthermore, the = experiment does suggest that no living process need be involved in the = bulk=20 flow of a tree.</SPAN></P> <P><SPAN class=3Dbodyp>This would result in a downward flow caused by = the=20 liberated solutes and this would in turn generated suction at the base = of the=20 tree sufficient to draw in more dilute solution from the bath, and = that this=20 flow would continue until the liberated salts and sugars had either = all=20 reached the picric acid / copper sulphate bath, or that the liberated = salts=20 and sugars had changed the density of the fluid within the tub to=20 counterbalance any falling solutes.</SPAN></P> <P><SPAN class=3Dbodyp><B xmlns:script=3D"urn:my-script-blocks">Andrew = K=20 Fletcher</B>, UK </SPAN></P></BLOCKQUOTE></FONT></BODY></HTML> ------=_NextPart_000_013D_01C6865D.8B0D4120-- ======== Welcome All Anatomists! ========== About this IAWA Discussion Group, subscribing, unsubscribing, and archives: http://www.cof.orst.edu/org/IAWA About the IAWA and/or the IAWA Journal: http://www.kuleuven.ac.be/bio/sys/iawa The International Association of Wood Anatomists
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