Ac a Sil . Lign. Hung., Vol. 7 (2011) 97–108
Diu nal and Seasonal Changes in
S em Radius Inc emen and Sap Flow Densi y Indica e
Di e en Responses o Two Co-exis ing Oak Species o
D ough S ess
Ilona M
ÉSZÁROS
a*
– Pé e K
ANALAS
a
– And ás F
ENYVESI
b
– Józse
K
IS
a
–
Balázs N
YITRAI
a
– E zsébe S
ZŐLLŐSI
a
– Vik o O
LÁH
a
–
Zi a D
EMETER
a
– Ágnes L
AKATOS
a
– Is án A
NDER
b
a Depa men o Bo any, Facul y o Science and Technology, Uni e si y o Deb ecen, Deb ecen, Hunga y
b Sec ion o Cyclo on Applica ions, Nuclea Resea ch Ins i u e Deb ecen, Hunga y
Abs ac – Using con inuous moni o ing o s em adius combined wi h sap low measu emen s we
assessed he e ec s o en i onmen al condi ions on ee adial g ow h and wa e s a us o wo co-
exis ing oak species (Que cus pe aea and Que cus ce is) a high esolu ion ime in g owing
seasons o 2008 and 2009. The o es (95–100 y ) is si ua ed in a xe ic si e in he ansi ion zone
be ween o es ed and o es -s eppe egions in no h-eas e n Hunga y, Bükk moun ains (47
o
90’N,
20
o
46’E, ele a ion 320–340 m a.s.l.). Wea he condi ions in he g owing season o 2008 ( o al
ain all 354 mm, mean daily empe a u e 17.0
o
C) was less ex eme han in 2009 ( o al ain all
299 mm, empe a u e 17.9
o
C). Rain all s ongly de e mined he cou se o adial g ow h inc emen
in ees. Radial g ow h o ees was limi ed in 2009 due o he d ough in sp ing. The maximum
adial inc emen o bo h species was achie ed h ee weeks ea lie (4
h
week o June) han in 2008
(4
h
week o July). We used dend ome e moni o ing da a o es ima ion o s em ( ee) wa e
de ici (∆W) by measu ing wa e - ela ed changes in s em adius (Zwei el e al. 2005). The
magni ude o ee wa e de ici a ia ion (∆W) was always smalle in Q. ce is han in Q. pe aea.
In con as , Que cus ce is always exhibi ed la ge day ime a e ages and maxima o sap low
densi y. In Augus o 2009 when d ough became se e e he e we e la ge inc eases in ee wa e
de ici (∆W) (50–55 %) in bo h species compa ed o July as i could be expec ed om he ex en
o dec eases in sap low densi y (24–28%). Ou da a sugges ed ha due o he low SWC he
anspi a ion was suppo ed mainly om he inne wa e s o age o ees du ing p olonged d ough
which esul ed in high s em wa e de ici (∆W).
d ough / o es /po en ial e apo anspi a ion / Que cus pe aea / Que cus ce is / s em ( ee)
wa e de ici
Ki ona – Ké zonális ölgy aj ö zsnö ekedésének és ned á amlásának napi és szezonális
dinamikája. A anulmányban össze oglal e edmények észé képezik a Bükk-hegységi Sík őkú
P ojec LTER ku a ási e üle (47
o
90’N, 20
o
46’E, sz . 320–340 m) cse es- ölgyes e dőállományban
olyó nö ény-öko iziológiai ku a ási p og amnak. Vizsgála aink so án olyama os dend ome iás és
ned á amlás mé éseke égez ünk a 2008 és 2009 é ek ege ációs időszakaiban annak megállapí ásá a,
hogy a kocsány alan ölgy (Que cus pe aea (Ma .) Liebl.) és a cse ölgy (Que cus ce is L.) adiális
* Co esponding au ho : imm[email p o ec ed]; H-4032 DEBRECEN, Egye em é 1.
Mészá os, I. e al.
Ac a Sil . Lign. Hung. 7, 2011
98
ö zsnö ekedésében és íz o galmában az időjá ási ex émi ások milyen mé ékű ál ozásoka
okoznak. A dend ome iás mé ési e edmények az jelzik, hogy a csapadék mennyisége és eloszlása
dön ően megha á ozza a ö zsek adiális nö ekedésé mindké ajnál. Minké aj ese ében kimu a uk,
hogy a 2009 é i a aszi aszály ha ásá a a ö zsek adiális nö ekedése há om hé el ko ábban
be ejeződö és alacsonyabb é éke é el a 2008 é i nö ekedéshez képes . A ö zs adiális
ál ozásának a inom idő elbon ású mé ése a nö ekedési ü emen kí ül lehe ősége nyúj o a a is,
hogy az ada ok alapján a ö zsek ( ák) ízde ici é ékei (∆W) is megbecsüljük, amelyhez Zwei el e
al. (2005) módsze é használ uk el. A ké a aj közül a ízde ici a Q. pe aea ö zsében mindig
szigni ikánsan nagyobb ampli údójú ál ozásoka mu a o , min a Q. ce is ese ében, ami alapján az
u óbbi ajnál nagyobb ö zsbeli ízkészle e kö e kez e ünk. Ugyanakko a ned á amlás nappali
középé éke és maximuma mindig a Que cus ce is ese ében ol magasabb. 2009 augusz usában,
e ősen aszályos időszakban mindké ajnál jó al nagyobb mé ékben (50–55%-kal) emelkede a
a ö zsbeli ízde ici a júliusi mé ési e edményekhez képes , min ami az ugyanezen időszakban mé
ned á amlás csökkenés mé éke alapján á nánk (24–28%). Ez az sugallja, hogy a ák a a ósan
aszályos pe iódusokban a belső, ö zsbeli íz ak á aka hasznosí ják a ízszállí ó pályák el öl ésé e és
a anszpi áció enn a ásá a.
aszály / ned á amlás / Que cus pe aea / Que cus ce is / adiális ö zsnö ekedés / ízde ici
1 INTRODUCTION
Owing o clima e change (IPCC, 2007) he u u e su i al and sus ainabili y o o es
ecosys ems has become o g ea conce n (Jump e al. 2009, Má yás 2010). Fo Ca pa hian
basin clima e p ojec ions p edic a educ ion in he o al a ea o clima e-zonal o es s and he
g adual shi „ o wa d” o ansi ion be ween o es and o es -s eppe zones (Má yás
–
Czimbe 2004). Se e e and ecu ing d ough has been iden i ied as majo con ibu ing ac o
o he ecen ly accele a ed ee decline and mo ali y in Eu ope (e.g. Jakucs e al. 1986,
Gibbs
–
G eig 1997, Siwecki
–
U nalski 1998, Thomas e al. 2002).
In Hunga y se ious ee decline has been epo ed o he mixed s ands o sessile oak
(Que cus pe aea (Ma .) Liebl) and Tu key oak (Que cus ce is L.) om he 80’s (Jakucs
e al. 1986). These o es s ep esen one o he mos impo an ege a ion ype in he
Ca pa hian basin he e o e ee decline has la ge economic and na u e conse a ion
consequences. Sessile oak su e ed mo e d as ic decline han Tu key oak in Hunga ian
o es s as well as in whole Eu ope. Mo ali y o sessile oak a ied wi h si e condi ions and
became e y se ious in xe ic ma gins o his o es ype sugges ing ha clima e change
will h ea en sessile oak e y s ongly. Simula ion o u u e dis ibu ion o sessile oak by
BIOMOD model (Thuille 2003) p ojec s ha he e will be a shi o i s bioclima ic
en elope as a esul o clima e change. On egional scale, analyses p o ided also a e y
pessimis ic scena io o Hunga y since he species may loose he majo i y o he
dis ibu ion a ea by 2080 (Czúcz e al. 2011).
The objec i e o his wo k was o analyse he e ec s o clima ic luc ua ions on g ow h
and wa e s a us o wo co-exis ing ee species (Que cus pe aea (Ma .) Liebl. and Que cus
ce is L.) in wo subsequen g owing seasons, 2008 and 2009. Mo e speci ically we in ended
1) o es ima e he in luence o en i onmen al condi ions on s em adius inc emen wi h high
ime esolu ion; 2) o assess d ough ela ed esponses o ee wa e de ici o he wo species;
3) o desc ibe seasonal and diu nal cou se o sap low densi y and i s co ela ion wi h
en i onmen al ac o s.
Diu nal and seasonal changes in s em adius inc emen and sap low densi y
Ac a Sil . Lign. Hung. 7, 2011
99
2 MATERIAL AND METHODS
2.1 S udy si e and expe imen al ees
The s udy was ca ied ou a Sík őkú P ojec LTER o es si e (47o90’N, 20o46’E, ele a ion
320–340 m a.s.l.), Bükk Moun ains, no h-eas e n Hunga y in summe o 2008 and 2009.
The si e is co e ed by a mixed o es s and (95–100 y ) domina ed by sessile oak
(Que cus pe aea) and Tu key oak (Que cus ce is) in he canopy laye . The soil o he si e is
a deep b own o es soil o med on miocenic pebble (Jakucs 1985). Acco ding o he cu en
clima ic condi ions he si e is close o he o es -s eppe limi . The a e age annual ain all o
he pas 30 yea s is 555 mm and he mean annual empe a u e is 10.3 oC a he si e (Table 1).
The g owing season usually las s om mid-Ap il o mid-Oc obe . In he no he n moun ain
egion o Hunga y he annual o al o global adia ion alls be ween 4300–4400 MJ m–2
(Jakucs 1985). Du ing he pas decade ex eme d ough and hea -wa es ha e appea ed a he
si e in summe o 2003, 2007 and 2009.
The ee species composi ion o he s and was: Que cus pe aea 46.9%, Que cus ce is
22.8%, Ca pinus be ulus 0.4%, Ace campes e 28.2%, Ace a a icum 0.9%, Ce asus a ium
0.8%. T ees o oak species belong o he dominan and co-dominan c own classes, while
o he ee species ep esen in e media e and co-dominan c own classes o o es canopy.
Fo ou s udy we selec ed one ma u e sessile oak and one Tu key oak (95–100 yea s old).
Bo h ees ep esen ed he dominan c own class g owing o uppe mos posi ion o he o es
canopy (heigh o expe imen al ees was 20–22 m, DBH o he sessile oak ee was 29 cm,
o Tu key oak 46 cm).
2.2 Measu emen s o en i onmen al pa ame e s
Wea he condi ions we e moni o ed au oma ically by Hobo P oSe ies RH&Temp senso
(Onse Compu e Co po a ion, Pocasse , USA), and Hobo Mic o S a ion (Onse Compu e
Co po a ion, Pocasse , USA) wi h ex e nal senso s (Rain gauge, PAR, a mosphe ic p essu e,
wind speed) du ing he s udy pe iod. Wea he da a we e eco ded a e e y 30 min. a he op
o a me eo ological owe (25m abo e g ound). Volume ic soil mois u e con en (SWC) was
measu ed using ECH2O senso s (Decagon De ices, Pullmann WA, USA) wi hin he uppe
30 cm wi h 15 min sampling in e al.
To assess he di e ences in he mic oclima ic condi ions be ween ege a ion seasons o
2008 and 2009 we calcula ed he cumula i e daily mean empe a u e and cumula i e ain all.
Cumula i e daily mean empe a u e and ain all da a and cou se o soil mois u e in 2008 and
2009 a e p esen ed in Figu e 1. Due o he lack o measu emen s o global adia ion, he
Ha g ea es-Samani empe a u e based me hod was used o es ima e he he mean daily
po en ial e apo anspi a ion (PET mm day–1) (Ha g ea es
–
Samani 1982).
2.3 Sap low measu emen s
Con inuous sap low measu emen s began a ou si e in g owing season o 2009. Sap low
densi y (ml cm–2 min–1) was measu ed wi h hea dissipa ion me hod de eloped by G anie
(1985). An SF-G senso (Ecoma ik, GmbH, Dachau, Ge many) was moun ed on he no he n
side o ee s ems o a oid di ec sola hea ing and shielded wi h aluminum oil o minimize
empe a u e luc ua ions in he sapwood. The SF-G senso consis s o wo iden ical needles wi h
coppe -cons an an he mocouples and a special hea ing wi e. The wo needles we e inse ed
2 cm in o he sapwood, one abo e he o he , 15 cm apa . The uppe needle was ins alled a a
heigh o 1.5 m. The op needle was hea ed wi h cons an ene gy supply (a 12V wi h 83 mA).
The empe a u e di e ence be ween he wo needles (∆T) was he ou pu signal o he senso
and used o calcula ion o sap low densi y acco ding o he o mula by G anie (1985):
Mészá os, I. e al.
Ac a Sil . Lign. Hung. 7, 2011
100
u = 0.714*[(∆Tmax–∆T)/∆T]1.231,
whe e
∆T is empe a u e di e ence be ween wo needles;
∆Tmax is he maximum alue o ∆T when sap low can be conside ed as 0 du ing nigh .
SF-G Senso s we e ins alled on Ma ch 26 2009 and moni o ing o ∆T was planned in
5 min in e al ill he end o Oc obe bu he e we e some sho pe iods du ing he g owing
season when unexpec ed e o s (due o hea y ain e en s, animal damages e c.) dis up ed he
con inuous measu emen .
2.4 Measu emen s o ee s em adius changes and es ima ion o ee wa e de ici
T ee s em adius changes (∆ ) we e moni o ed wi h au oma ed DR dend ome e s (Ecoma ik
Gmbh, Dachau, Ge many) wi h esolu ion up o 0.2 mic ons. The dend ome e s we e
moun ed a 1m abo e g ound on no h side o s em o one sessile oak and one Tu key oak
ee. Con inuous eco ding o s em adius changes began on June 6 2008. ∆ was eco ded in
10 min in e als.
A senso ixed in a ame was ins alled o he measu ing sec ion o he s em a e
emo al o he dead ba k. Senso s we e ins alled ca e ully o a oid damages o he li ing
issues below he dead ba k. The cou se o ∆ depends mainly on s em adial g ow h and
luc ua ion o wa e -s o age. O he ac o s e.g. empe a u e and xylem- ension- ela ed
luc ua ions may con ibu e only sligh ly (<10%) o ∆ (Zwei el e al. 2005). F om he
cou se o ∆ we es ima ed he changes in s em wa e -s o age by using he algo i hm
sugges ed by Zwei el e al. (2005). We hypo hesized ha a ain all e en abo e 10 mm
can induce s em hyd a ion and inc ease o o maximum. The di e ence be ween he
unk adius o maximum hyd a ed (no mally a e a ain all e en ) s a e and ac ual
hyd a ion s a us was used o quan i ying he deg ee o s em wa e de ici (∆W) du ing a
gi en pe iod. This is also conside ed as a measu e o wa e de ici in he whole ee and
de ined as ee wa e de ici (Hinckley
–
Lassoie 1981).
3 RESULTS
3.1 Wea he and soil mois u e condi ions
Compa ed o he a e age wea he condi ions o he las 30 yea s (1978–2007), annual mean
empe a u e was highe by 0.9–1 oC in 2008 and 2009 (Table 1).
The ege a ion pe iod o bo h s udy yea s was wa me and d ie han he a e age.
Summe o 2009 was ex ao dina ily ho and had one o he lowes o al amoun s o ain
du ing he las decade (Figu e 1). Howe e , in 2009 he o al annual ain all did no di e
om he 30 yea a e age while in 2008 i was 56 mm lowe (Table 1).
In 2009 he e was a ou -week pe iod wi hou ain all du ing budbu s in Ap il which led
o apid decline o soil mois u e con en (Figu e 1). The whole ege a ion pe iod o 2009 was
d ie and wa me han in 2008 wi h low olume ic wa e con en . In 2009 he end o
ege a ion pe iod was wi hou ain e en s ha caused la ge wa e de ici s in he soil in
Sep embe . Du ing he ege a ion pe iod o 2008 he soil was we in sp ing. Volume ic soil
wa e con en ansien ly dec eased in May, bu i inc eased in June and July due o equen
ains.
Diu nal and seasonal changes in s em adius inc emen and sap low densi y
Ac a Sil . Lign. Hung. 7, 2011
101
Table 1. Annual mean o ai empe a u e (T), mean daily ai empe a u e o ege a ion
pe iod (
T04–10)
, annual o al ain all (P) and o al ain all o ege a ion pe iod (
P04–10)
in
2008 and 2009. Long- e m mean alues o ai empe a u e and ain all we e
calcula ed o 1978–2007
T
oC T04–10
oC P
mm P04–10
mm
2008 11,3 17,0 499 354
2009 11,3 17,9 554 299
30-yea mean
(1978–2007) 10,4 16,5 555 393
Cumula i e ain all (mm)
0
50
100
150
200
250
300
350
Cumula i e daily mean empe a u e (oC)
0
1000
2000
3000
4000
5000
ain all 2008
ain all 2009
T oC 2009
T oC 2008
DOY
100 120 140 160 180 200 220 240 260 280 300
soil wa e con en (m
3
m
-3
)
0,06
0,08
0,10
0,12
0,14
0,16
0,18
0,20
0,22
0,24
2009
2008
Figu e 1. Cumula i e alues o daily mean ai empe a u e, cumula i e daily p ecipi a ion
(uppe igu e) and olume ic soil wa e con en (lowe igu e) du ing he g owing seasons o
2008 and 2009 in he Sík őkú s udy a ea
3.2 S em adius changes and a ia ion in ee wa e de ici
Dend ome e s we e ins alled on ee s ems on June 6 2008. We selec ed a h ee-mon h pe iod
be ween DOY158 and 248 in 2008 and 2009 o compa ison o s em adius changes (∆ ).
Al hough he cou se o ∆ was di e en in 2008 and 2009, he s em adial inc emen did no
change a e DOY 248 in bo h yea s (Figu e 2). DOY 158 is conside ed as e e ence day and
∆ alues show de ia ions om i .
The dend ome e da a was se as 0 on he i s day o his selec ed pe iod. Du ing he
h ee-mon h pe iod in 2009 he e was only 750–850 µm maximum inc emen o Que cus
pe aea 500–600 µm o Que cus ce is. S em adius s opped o inc ease by he i s week o
July 2009 and hen only sho - e m luc u a ions occu ed due o he daily anspi a ion and
ain all e en s.

Mészá os, I. e al.
Ac a Sil . Lign. Hung. 7, 2011
102
In 2008, howe e , bo h species showed h ee o ou imes la ge s em adius inc ease in
he co esponding pe iod han in 2009 (Figu e 2). In he co esponding pe iod o 2008 he
s em adius change was 2100–2300 µm o Que cus pe aea and 1800–2100 µm o Que cus
ce is in he h ee mon h pe iod. In 2008 he s em adius showed inc eases ill he end o July.
2008
s em adius change (µm)
0
500
1000
1500
2000
2500
3000
ain all (mm)
0
5
10
15
20
25
30
Q. ce is
Q. pe aea
ain all
2009
DOY
160 180 200 220 240
s em adius change (µm)
0
500
1000
1500
2000
2500
ain all (mm)
0
5
10
15
20
25
Figu e 2. Tempo al cou se o cumula i e s em adius change (
∆
) o
Que cus pe aea (black line) and o Que cus ce is (g ay line) and daily sums o ain all in
summe o 2008 and 2009. DOY 158 is conside ed as e e ence day and
∆
alues show
de ia ion om i
The h ee-mon h long dend ome e da a se ies we e also used o es ima e luc ua ions in
wa e s a us o ee s ems. Seasonal a ia ions in s em wa e de ici calcula ed by means o
me hod sugges ed by Zwei el (2005) a e p esen ed in Figu e 3.
The gene al seasonal cou se o ∆W was simila o he wo species in bo h yea s.
Seasonal ampli ude o s em wa e de ici di e ed in he wo species, i was smalle o
Que cus ce is han o Que cus pe aea.
Va ia ion o s em wa e de ici was, howe e , usually he mos signi ican du ing d y
pe iods and app oached ze o a e hea y ain e en s. E en one- wo week d y pe iods could
induce apid inc eases o ee wa e de ici depending on he soil wa e a ailabili y and VPD.
In 2008 la ge s em wa e de ici de eloped wi hin he pe iod om DOY 175 o DOY 190 (4 h
week o June and 1s week o July) up o 250 µm o Que cus ce is, and 500 µm o Que cus
pe aea and be ween DOY 223 and DOY 236 up o 230 µm and 420 µm o Que cus ce is
and Que cus pe aea, espec i ely. In 2009 a long-las ing s em wa e de ici pe iod appea ed
om DOY 200 o DOY 234 wi h 300 and 450 µm maximum alues o ∆W o o Que cus
ce is and Que cus pe aea, espec i ely. The e was only a sho (3 days) in e up ion o his
pe iod when ∆W o s em app oached 0 in bo h species. The diu nal luc ua ion o ∆W we e
also di e en in he wo species (Figu e 3).
Diu nal and seasonal changes in s em adius inc emen and sap low densi y
Ac a Sil . Lign. Hung. 7, 2011
103
2008
s em wa e de ici (µm)
0
250
500
Q. ce is
Q. pe aea
2009
DOY
160 170 180 190 200 210 220 230 240
s em wa e de ici (µm)
0
250
500
Figu e 3. Va ia ion in s em ( ee) wa e de ici (∆W,
µ
m) wi h ime o
Que cus pe aea (black line) and Que cus ce is (g ay line)
On mos sampling days in 2008 bo h species showed lowe diu nal ampli udes o ∆W
han in 2009. In 2008 diu nal ampli ude o ∆W eached 80–120 µm in Que cus pe aea and
40–80 µm in Que cus ce is. In 2009 he diu nal a ia ion o s em adius ex ended o
130–200 µm in Que cus pe aea and o 40–100 µm in Que cus ce is.
3.3 Va ia ion o main day ime sap low densi y and co ela ion wi h PET in
summe o 2009
In he second hal o he ege a ion pe iod o 2009 we expe ienced se e e d ough a he si e.
Du ing he expe imen al pe iod om DOY 209 o DOY 283 mean day ime sap low densi y
anged be ween 0.11 and 0.04 ml cm–2 min–1 in Que cus ce is, and 0.07 and 0.02 ml cm–2 min–1
in Que cus pe aea. Du ing he same pe iod he daily PET changed be ween 12 and 4 mm day–1.
DOY
209
211
215
221
222
223
224
225
226
227
228
229
230
231
232
233
234
238
239
240
244
245
246
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
mean day ime sap low densi y (ml cm
-2
min
-1
)
0,00
0,02
0,04
0,06
0,08
0,10
0,12
PET (mm day
-1
)
0
4
8
12
Q. ce is
Q. pe aea
PET
Figu e 4. Day ime mean sap low densi y o Que cus pe aea (black line) and Que cus ce is
(g ay line) and po en ial e apo anspi a ion es ima ed by Ha g ea es-Samani empe a u e
based me hod (Ha g ea es-Samani 1982) du ing he expe imen al pe iod om DOY 209 o
DOY 283. Rainy days a e excluded om he da a se
Mészá os, I. e al.
Ac a Sil . Lign. Hung. 7, 2011
104
A gene al dec easing end o mean day ime sap low densi y was obse ed o bo h
species as he d ough p oceeded in Augus and Sep embe (Figu e 4). Analysis o a da ase
om his pe iod (50 days a e exclusion o ainy days) showed ha he day ime sap low
densi y o bo h species changed in close posi i e co ela ion (P<0.01) wi h PET which also
showed declining end in he second pa o g owing season. The co ela ion was close o
Q. pe aea (R2=0.6248) han o Q. ce is (R2=0.7410).
3.4 Diu nal cou se o sap low densi y
F om he con inuous sap low measu emen s o 2009 we ha e selec ed days om wo
cha ac e is ic pe iods o assess he ela ionship be ween sap low densi y and en i onmen al
condi ions a daily scale.
i) DOY 209, DOY 211 and DOY 215 ep esen sunny days in a mode a ely ainy pe iod wi h
small ains on DOY 210 (1 mm), DOY 212 (7mm) and DOY 214 (3.4mm), dec easing SWC
( om 0.110 o 0.099 cm3 cm–3), high day ime VPD alues (VPDmax 3–4 KPa) and ligh
in ensi y (PPFDmax 1800–1900 µmol m–2 s–1). The e we e only wo small ains (<4 mm)
ain du ing he p e ious 10 days (Figu e 5).
ii) DOY 231, DOY 232 and DOY 233 in he d ies pe iod o summe wi h
SWC 0,080–0,083 cm3 cm–3, high daily VPD (VPDmax 2.9–3.6 kPa) and PAR (PPFD
1700–1800 µmol m–2 s–1). The e was no ain all e en in he p e ious 10 days (Figu e 6).
This pe iod ep esen ed ypical s age o he d ough s ess.
The magni ude o diu nal sap low ampli ude depended signi ican ly on he
en i onmen al condi ions on selec ed days and dec eased as he d ough s ess p oceeded on
sunny and ho days (DOY 209, 211 and 215) o a mode a ely ainy pe iod in July, he mean
SWC alue on he selec ed h ee days eached 0.10 cm3 cm–3. The low SWC sugges s ha in
July a signi ican deple ion o soil wa e ese es occu ed and small ains we e no enough
o soil e illing. Compa ing wi h o he pe iods o g owing season bo h ee species exhibi ed
ela i ely high s em wa e de ici on hese days (Figu e 3).
209
PPFD (µmol m
-2
s
-1
)
0
500
1000
1500
2000
211
VPD
PPFD
215
VPD (kPa)
0
1
2
3
4
209
sap low densi y
(ml cm
-2
min
-1
)
0,02
0,04
0,06
0,08
0,10
0,12
0,14
215
0,02
0,04
0,06
0,08
0,10
0,12
0,14
211
209
daily s em adial
changes (µm)
-150
-100
-50
0
50
100
150
200
215 -150
-100
-50
0
50
100
150
200
DOY
211
Q. pe aea
Q. ce is
Figu e 5. Diu nal cou se o VPD, ligh in ensi y (PPFD) and sap low densi y and
daily s em adial changes o Que cus pe aea and Que cus ce is on sunny days o a
mode a ely ainy pe iod in July 2009
Diu nal and seasonal changes in s em adius inc emen and sap low densi y
Ac a Sil . Lign. Hung. 7, 2011
105
On DOY 209–Doy 215 he mean daily s em wa e de ici (∆W) was 169 µm o Q. ce is
and 251 µm o Q. pe aea (Figu e 3). Be ween he wo selec ed pe iods sap low densi y o
bo h ee species was he highes on hese days. The day ime mean sap low was 0.10 ml cm2
min–1 in Q. ce is and 0.066 ml cm2 min–1 in Q. pe aea. The daily maximum o sap low was
ela i ely high and app oached 0.14 ml cm2 min–1 o Q.ce is and 0,09 ml cm2 min–1 o
Q. pe aea (Figu e 5). VPD was e y high on hese days and showed daily maximum
be ween 3.1 and 3.9 kPa. Sap low densi y was in close co ela ion wi h VPD bu showed a
maximum ea lie du ing he day. The s em adius eached maximum in he mo ning (be ween
6 and 8 a.m.) and minimum alues in he a e noon (be ween 4 and 6 p.m.). Tempo al
appea ance o minimum was closely ela ed o he maximum o VPD.
In 2009 a p og essi e d ough appea ed om he i s week o Augus which las ed
almos o he whole mon h and was in e up ed only by sho ain e en s (Figu e 1). SWC
eached i s minimal alue (0.0819 cm3 cm–3) in his mon h conside ing he whole summe
(Figu e 1). On he h ee selec ed ep esen a i e days o d ough pe iod (DOY 231–233) he
daily maximum o sap low was low in bo h ee species (0.101 ml cm2 min–1 and 0.064 ml
cm2 min–1 (Figu e 6). These sap low densi y alues we e 28 % (Q. ce is) and 24 %
(Q. pe aea) lowe han in July (Figu e 5).
Q. ce is exhibi ed e y simila diu nal cou se o sap low densi y as in July in
co ela ion wi h PPFD and pa ly wi h VPD oo. While Q. ce is showed maximum sap low
densi y a midday, Q. pe aea had a sho maximum o sap low densi y in he mo ning (a
VPD 2–2.5 kPa) ollowed wi h a g adual educ ion la e on he day. The ampli ude o diu nal
a ia ion in he s em adius was highe in Q. pe aea han in Q. ce is.
S em wa e de ici (∆W) was 55 % (Q. ce is) and 49 % (Q. pe aea) la ge we e deduced
han in July. Mean daily alue o ∆W was 263 µm o Q. ce is and 374 µm o Q. pe aea
(Figu e 3) sugges ing he educ ion o s em wa e s o age due o he d ough .
231
PPFD (µmol m-2 s-1)
0
500
1000
1500
2000
232
VPD
PPFD
233
VPD (kPa)
0
1
2
3
4
231
sap low densi y
(ml cm-2 min-1)
0,02
0,04
0,06
0,08
0,10
0,12
0,14
Q. ce is
Q. pe aea
233
0,02
0,04
0,06
0,08
0,10
0,12
0,14
232
231
daily s em adial
changes (µm)
-150
-100
-50
0
50
100
150
200
233 -150
-100
-50
0
50
100
150
200
DOY
232
Q. ce is
Q. pe aea
Figu e 6. Diu nal cou se o VPD, ligh in ensi y (PPFD) and sap low densi y and
daily s em adial changes o Que cus pe aea and Que cus ce is on sunny days
du ing he d ough in Augus 2009