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Dalby Söderskog : en studie av trädarternas sammansättning 1921 jämfört med 2005

Johansson, Hanna (2007) In Lunds universitets Naturgeografiska institution - Seminarieuppsatser
Dept of Physical Geography and Ecosystem Science
Abstract
The national park Dalby Söderskog is situated ten kilometres east of Lund and has
been a national park since 1918. The vegetation consists of a deciduous forest of Oak,
Beech, Elm, Ash and Alden. The forest is also famous thanks to its rich spring flora of
among others Anemóne nemorósa, Anemóne ranunculoídes and Corýdalis bulbosa. In
the summer of 1921 a map was drawn that shows the distribution of Dalby Söderskog
along with every tree in it (figure 1). This paper is based on that very map, but also on
other tree enumeration in the 20th century, such as one in 1935 when the young trees
in Dalby Söderskog were measured. During the years of 1928 to 1936 Lennart
Lindquist made a study concerning the hydro geographical conditions in... (More)
The national park Dalby Söderskog is situated ten kilometres east of Lund and has
been a national park since 1918. The vegetation consists of a deciduous forest of Oak,
Beech, Elm, Ash and Alden. The forest is also famous thanks to its rich spring flora of
among others Anemóne nemorósa, Anemóne ranunculoídes and Corýdalis bulbosa. In
the summer of 1921 a map was drawn that shows the distribution of Dalby Söderskog
along with every tree in it (figure 1). This paper is based on that very map, but also on
other tree enumeration in the 20th century, such as one in 1935 when the young trees
in Dalby Söderskog were measured. During the years of 1928 to 1936 Lennart
Lindquist made a study concerning the hydro geographical conditions in Dalby
Söderskog.
The aim of this study was first to digitise the 1921-map using ArcGIS9 then, using
field measurements, to check if there were any changes in the tree composition
comparing 1921 and present. It is also interesting to see if any particular tree species
are concentrated to a special area, and in that case why.
To make a digitalisation of and to place the coordinates in the tree map, some
fieldwork like collecting measuring points was needed. These points were used to fit
the map into the right coordinate system. The coordinates were taken at trees that
could be found both on the map and in reality. Within a ten metres radius every tree
was measured regarding its diameter. In order to digitise the map it was needed in a
digital format and was therefore scanned and saved as a TIF file to be used in
ArcGIS9. Every tree and measuring point was digitised and buffers with a ten metres
radius were created to be compared with the distribution of trees today.
The trees were divided into four groups according to its diameter size; group I (15-29
cm), group II (30-59 cm), group III (60-89 cm) and group IV (>90 cm). A study of the
forest’s rejuvenation was also made on every tree that had reached a height of 120 cm
and that had a diameter of <10 cm to be compared to the rejuvenation coefficients of
Lindquist from 1935. According to the diagrams (figure 26-29) beech was the
dominant tree in groups I, III and IV in 1921. Group II was dominated by elm. Today
groups I and II are dominated by elm, group III by beech and oak and group IV also
by beech. Looking at the total amount of trees at the measuring points, you can see
that elm has almost doubled while ash and beech have only increased with a few trees.
Oak and the remaining trees have decreased with a couple of specimens. If you look
at the rejuvenation of trees, that is the amount of young trees compared to the amount
of older trees, you will find that the ash had the better coefficient in 1921 while the
oak already then had the lowest rejuvenation rate. Today the elm has the fastest
rejuvenation rate but it and all the other tree species have shown a major decrease in
rejuvenation rate. The oak has apparently no rejuvenation today what so ever in the
measuring points.
The map showing the hydro geographical conditions was compared with the original
map to see if there was any connection between the water depth and the tree
distribution. A few connections were found, showing that the alder prefers to stand
with the roots in water while beech and elm grow better on a non-saturated ground. In
the end the oak has probably no chance of survival unless drastic measures are taken,
probably at the cost of other species. (Less)
Abstract (Swedish)
Dalby Söderskog är belägen tio kilometer öster om Lund och har varit nationalpark
sedan 1918. Växtligheten består av ädellövträd samt en rik vårflora av bland annat vitoch
gulsippor och skånsk nunneört. Sommaren 1921 utfördes en taxering av skogen
och en karta upprättades (figur 1). Kartan visar Söderskogens utbredning samt varje
träd i densamma. Arbetet grundar sig på just denna karta men tar även hänsyn till
andra taxeringar som gjorts under 1900-talet, speciellt den som utfördes 1935 då man
här också har mätt upp och räknat Söderskogens yngre träd. Åren 1928-1936 utförde
Lennart Lindquist även en hydrografisk undersökning rörande vattenförhållandena i
Söderskogen.
För att kunna göra en digitalisering och koordinatsättning av... (More)
Dalby Söderskog är belägen tio kilometer öster om Lund och har varit nationalpark
sedan 1918. Växtligheten består av ädellövträd samt en rik vårflora av bland annat vitoch
gulsippor och skånsk nunneört. Sommaren 1921 utfördes en taxering av skogen
och en karta upprättades (figur 1). Kartan visar Söderskogens utbredning samt varje
träd i densamma. Arbetet grundar sig på just denna karta men tar även hänsyn till
andra taxeringar som gjorts under 1900-talet, speciellt den som utfördes 1935 då man
här också har mätt upp och räknat Söderskogens yngre träd. Åren 1928-1936 utförde
Lennart Lindquist även en hydrografisk undersökning rörande vattenförhållandena i
Söderskogen.
För att kunna göra en digitalisering och koordinatsättning av kartan krävdes en del
fältarbete i form av att samla in punkter som kunde användas som passpunkter för
digitaliseringen av kartan. Koordinaterna togs vid träd som gick att identifiera både på
kartan och i verkligheten. Till detta användes en GPS inställd på koordinatsystemet
Rt-90 Rikets nät. Inom en zon med en radie av tio meter mättes varje träds diameter i
cm. För skärmdigitaliseringen behövdes kartan i digitalt format. Därför scannades den
in och sparades som en TIF-fil för att sedan kunna användas i ArcGIS9. Samtliga träd
och mätpunkter digitaliserades in och runt varje mätpunkt skapades en buffertzon, det
vill säga ett område med viss radie, här tio meter, kring en mätpunkt där denna är i
centrum. Alla träd inom buffertzonen räknades för att fördelningen av träden 1921
skulle kunna jämföras med fördelningen idag.
Träden delades upp i olika storleksklasser beroende på diameter; klass I (15-29 cm),
klass II (30-59 cm), klass III (60-89 cm) och klass IV (>90 cm). En studie av trädens
föryngring gjordes också, och då räknades alla träd som nått en höjd av 120 cm samt
hade en diameter <10 cm för att jämföras med Lindquists föryngringskoefficienter
från 1935. Fördelningen av träden 1921 i mätpunkterna (se figurerna 26-29) var sådan
att boken dominerade i storleksklasserna I, III och IV. Klass II dominerades av almen.
Idag domineras klass I och II av alm, klass III av bok och ek samt klass IV av bok.
När man ser till det totala antalet träd i mätpunkterna har almen nästan dubblats,
medan asken och boken endast ökat med något enstaka träd. Ek och övriga träd har
minskat med ett par stammar. Ser man till föryngringen av träd, det vill säga antal
unga träd jämfört med antal vuxna träd, ser man att asken föryngrade sig bäst 1921
medan eken redan då hade en väldigt dålig föryngringstakt. Idag är det almen som har
den största föryngringen men samtliga trädarter har minskat andelen unga träd
markant och eken har ingen föryngring alls i mätpunkterna.
Kartan över de hydrogeografiska förhållandena (figur 14) jämfördes med den
ursprungliga kartan över Dalby Söderskog för att se om det fanns något samband
mellan markvatten och trädartsfördelning. Man kan se att några trädarter föredrar
speciella vattenförhållanden. Till exempel trivs alen bäst med att ha rötterna i vatten
och växer inte alls på de torraste markerna, boken växer mest på de lite torrare
ställena medan eken och asken verkar föredra ett mellanting. Aspen verkar föredra
fuktigare mark medan almen trivs bättre på torrare mark. Troligtvis kommer eken att
försvinna från skogen sedan de gamla träden fallit. För att bevara eken krävs drastiska
åtgärder, förmodligen på bekostnad av andra arter. Söderskogen måste i så fall huggas
ur ordentligt med jämna mellanrum för att ekarna ska få ljus och plats och för att
föryngringen ska komma igång igen och fortsätta. (Less)
Please use this url to cite or link to this publication:
author
Johansson, Hanna
supervisor
organization
year
type
H1 - Master's Degree (One Year)
subject
keywords
trädarternas sammansättning, geografi, naturgeografi, ArcGIS9, Dalby Söderskog
publication/series
Lunds universitets Naturgeografiska institution - Seminarieuppsatser
report number
135
language
Swedish
id
1950740
date added to LUP
2011-05-10 11:55:52
date last changed
2011-12-14 10:06:39
@misc{1950740,
  abstract     = {The national park Dalby Söderskog is situated ten kilometres east of Lund and has
been a national park since 1918. The vegetation consists of a deciduous forest of Oak,
Beech, Elm, Ash and Alden. The forest is also famous thanks to its rich spring flora of
among others Anemóne nemorósa, Anemóne ranunculoídes and Corýdalis bulbosa. In
the summer of 1921 a map was drawn that shows the distribution of Dalby Söderskog
along with every tree in it (figure 1). This paper is based on that very map, but also on
other tree enumeration in the 20th century, such as one in 1935 when the young trees
in Dalby Söderskog were measured. During the years of 1928 to 1936 Lennart
Lindquist made a study concerning the hydro geographical conditions in Dalby
Söderskog.
The aim of this study was first to digitise the 1921-map using ArcGIS9 then, using
field measurements, to check if there were any changes in the tree composition
comparing 1921 and present. It is also interesting to see if any particular tree species
are concentrated to a special area, and in that case why.
To make a digitalisation of and to place the coordinates in the tree map, some
fieldwork like collecting measuring points was needed. These points were used to fit
the map into the right coordinate system. The coordinates were taken at trees that
could be found both on the map and in reality. Within a ten metres radius every tree
was measured regarding its diameter. In order to digitise the map it was needed in a
digital format and was therefore scanned and saved as a TIF file to be used in
ArcGIS9. Every tree and measuring point was digitised and buffers with a ten metres
radius were created to be compared with the distribution of trees today.
The trees were divided into four groups according to its diameter size; group I (15-29
cm), group II (30-59 cm), group III (60-89 cm) and group IV (>90 cm). A study of the
forest’s rejuvenation was also made on every tree that had reached a height of 120 cm
and that had a diameter of <10 cm to be compared to the rejuvenation coefficients of
Lindquist from 1935. According to the diagrams (figure 26-29) beech was the
dominant tree in groups I, III and IV in 1921. Group II was dominated by elm. Today
groups I and II are dominated by elm, group III by beech and oak and group IV also
by beech. Looking at the total amount of trees at the measuring points, you can see
that elm has almost doubled while ash and beech have only increased with a few trees.
Oak and the remaining trees have decreased with a couple of specimens. If you look
at the rejuvenation of trees, that is the amount of young trees compared to the amount
of older trees, you will find that the ash had the better coefficient in 1921 while the
oak already then had the lowest rejuvenation rate. Today the elm has the fastest
rejuvenation rate but it and all the other tree species have shown a major decrease in
rejuvenation rate. The oak has apparently no rejuvenation today what so ever in the
measuring points.
The map showing the hydro geographical conditions was compared with the original
map to see if there was any connection between the water depth and the tree
distribution. A few connections were found, showing that the alder prefers to stand
with the roots in water while beech and elm grow better on a non-saturated ground. In
the end the oak has probably no chance of survival unless drastic measures are taken,
probably at the cost of other species.},
  author       = {Johansson, Hanna},
  keyword      = {trädarternas sammansättning,geografi,naturgeografi,ArcGIS9,Dalby Söderskog},
  language     = {swe},
  note         = {Student Paper},
  series       = {Lunds universitets Naturgeografiska institution - Seminarieuppsatser},
  title        = {Dalby Söderskog : en studie av trädarternas sammansättning 1921 jämfört med 2005},
  year         = {2007},
}