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Spatial Variation in Near-Ground Radiation and Low Temperature - Interactions with Forest Vegetation

Blennow, Kristina LU (1997)
Abstract (Swedish)
Popular Abstract in Swedish

Låg temperatur begränsar i stor utsträckning överlevnad och expansion av vegetation. Under senare år har samverkan mellan låg temperatur och hög instrålning, som leder till försämrad fotosynteseffektivitet, rönt stor uppmärksamhet.



I denna avhandling tillämpas nya metoder för att relatera rumsliga variationer i temperatur och instrålning till fotosynteseffektivitet och tillväxt hos trädplantor samt för modellering av rumsliga temperaturvariationer i mikro- och lokal skala i heterogen terräng.



Metodologierna innefattar utveckling och användning av ett digitalt bildanalyssytem för ?fisheye?-fotografier, användning av Geografiska InformationsSystem (GIS) och... (More)
Popular Abstract in Swedish

Låg temperatur begränsar i stor utsträckning överlevnad och expansion av vegetation. Under senare år har samverkan mellan låg temperatur och hög instrålning, som leder till försämrad fotosynteseffektivitet, rönt stor uppmärksamhet.



I denna avhandling tillämpas nya metoder för att relatera rumsliga variationer i temperatur och instrålning till fotosynteseffektivitet och tillväxt hos trädplantor samt för modellering av rumsliga temperaturvariationer i mikro- och lokal skala i heterogen terräng.



Metodologierna innefattar utveckling och användning av ett digitalt bildanalyssytem för ?fisheye?-fotografier, användning av Geografiska InformationsSystem (GIS) och statistiska metoder, fältdatainsamling av meteorologiska element, vegetationsstruktur, tillväxt och fotosynteseffektivitet.



Temperatur och mängd mottagen direkt solstrålning relaterades till klorofyll a fluorescens och torrvikt hos trädplantor som vuxit under olika mikroklimatiska betingelser. För plantor som växte just innanför skogsbryn ledde kombinationen av ökande instrålning och sjunkande minimitemperatur med årstiden till kraftig försämring av fotosynteseffektiviteten med sannolik betydelse för etableringen av trädplantor vid skogsbryn och under skärmställningar.



I modellerna av rumslig temperaturvariation användes ?sky view factor? för att uppskatta avkylningen av markytan under nätter med risk för låg temperatur samtidigt som dränering, uppdämning och stagnation av kalluft liksom markens termala egenskaper beaktades.



Modellerna indikerar vilka skalor och processer som styr bildandet av rumsliga mönster i låg temperatur, vilket kan användas vid konstruktion av motsvarande mekanistiska modeller. Metodologin lämpar sig väl för kartering av potentiell och befintlig frostrisk efter avverkning av skog samt för att jämföra storlek av effekter på låg temperatur av skogsbruksåtgärder, såsom skärmställningar och markberedning. Resultaten kan också användas för att formulera tumregler för praktiskt skogsbruk. (Less)
Abstract
Low temperature has a large impact on the survival and distribution of plants. Interactive effects with high irradiance lead to cold-induced photoinhibition, which may impact on the establishment and growth of tree seedlings. In this thesis, novel approaches are applied for relating the spatial variability in low temperature and irradiance to photosynthetic performance and growth of tree seedlings, and for modelling the micro- and local-scale spatial variations in low temperature for heterogeneous terrain.



The methodologies include the development and use of a digital image analysis system for hemispherical photographs, the use of Geographic Information Systems (GIS) and statistical methods, field data acquisition of... (More)
Low temperature has a large impact on the survival and distribution of plants. Interactive effects with high irradiance lead to cold-induced photoinhibition, which may impact on the establishment and growth of tree seedlings. In this thesis, novel approaches are applied for relating the spatial variability in low temperature and irradiance to photosynthetic performance and growth of tree seedlings, and for modelling the micro- and local-scale spatial variations in low temperature for heterogeneous terrain.



The methodologies include the development and use of a digital image analysis system for hemispherical photographs, the use of Geographic Information Systems (GIS) and statistical methods, field data acquisition of meteorological elements, plant structure, growth and photosynthetic performance.



Temperature and amounts of intercepted direct radiant energy for seedlings on clear days (IDRE) were related to chlorophyll a fluorescence and the dry weight of seedlings. The combination of increased IDRE with reduced minimum temperatures resulted in persistent and strong photoinhibition as the season progressed, with likely implications for the establishment of tree seedlings at forest edges, and within shelterwood. For models of spatial distribution of low air temperature, the sky view factor was used to parameterise the radiative cooling, whilst drainage, ponding and stagnation of cold air, and thermal properties of the ground were all considered.



The models hint at which scales and processes govern the development of spatial variations in low temperature for the construction of corresponding mechanistic models. The methodology is well suited for detecting areas that will be frost prone after clearing of forest and for comparing the magnitudes of impacts on low air temperature of forest management practices, such as shelterwood and soil preparation. The results can be used to formulate ground rules for use in practical forestry. (Less)
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author
opponent
  • Professor Perttu, Kurth, Swedish University of Agricultural Sciences, Department of Short Rotation Forestry, Box 7016, SE-750 07 Uppsala, Sweden
organization
publishing date
type
Thesis
publication status
published
subject
keywords
light interception, hemispherical photograph, growth, forest fragmentation, fluorescence, cold-induced photoinhibition, GIS, view factor, radiative cooling, frost protection, agro-climatic mapping, forest clear-cut, local climate, Microclimate, Physical geography, geomorphology, pedology, cartography, climatology, Fysisk geografi, geomorfologi, marklära, kartografi, klimatologi
pages
106 pages
publisher
Lund University Press
defense location
Main Lecture Hall, Department of Physical Geography, Sölvegatan 13, Lund
defense date
1997-10-31 10:15
external identifiers
  • other:ISRN: LUNBDS/NBNG--96/1132--SE
  • scopus:0031421513
ISSN
0346-6787
ISBN
91-7966-443-1
language
English
LU publication?
yes
id
9f02131d-28fb-4641-8d86-11fe92da1e6f (old id 29613)
date added to LUP
2007-06-13 09:18:31
date last changed
2017-01-01 06:50:08
@phdthesis{9f02131d-28fb-4641-8d86-11fe92da1e6f,
  abstract     = {Low temperature has a large impact on the survival and distribution of plants. Interactive effects with high irradiance lead to cold-induced photoinhibition, which may impact on the establishment and growth of tree seedlings. In this thesis, novel approaches are applied for relating the spatial variability in low temperature and irradiance to photosynthetic performance and growth of tree seedlings, and for modelling the micro- and local-scale spatial variations in low temperature for heterogeneous terrain.<br/><br>
<br/><br>
The methodologies include the development and use of a digital image analysis system for hemispherical photographs, the use of Geographic Information Systems (GIS) and statistical methods, field data acquisition of meteorological elements, plant structure, growth and photosynthetic performance.<br/><br>
<br/><br>
Temperature and amounts of intercepted direct radiant energy for seedlings on clear days (IDRE) were related to chlorophyll a fluorescence and the dry weight of seedlings. The combination of increased IDRE with reduced minimum temperatures resulted in persistent and strong photoinhibition as the season progressed, with likely implications for the establishment of tree seedlings at forest edges, and within shelterwood. For models of spatial distribution of low air temperature, the sky view factor was used to parameterise the radiative cooling, whilst drainage, ponding and stagnation of cold air, and thermal properties of the ground were all considered.<br/><br>
<br/><br>
The models hint at which scales and processes govern the development of spatial variations in low temperature for the construction of corresponding mechanistic models. The methodology is well suited for detecting areas that will be frost prone after clearing of forest and for comparing the magnitudes of impacts on low air temperature of forest management practices, such as shelterwood and soil preparation. The results can be used to formulate ground rules for use in practical forestry.},
  author       = {Blennow, Kristina},
  isbn         = {91-7966-443-1},
  issn         = {0346-6787},
  keyword      = {light interception,hemispherical photograph,growth,forest fragmentation,fluorescence,cold-induced photoinhibition,GIS,view factor,radiative cooling,frost protection,agro-climatic mapping,forest clear-cut,local climate,Microclimate,Physical geography,geomorphology,pedology,cartography,climatology,Fysisk geografi,geomorfologi,marklära,kartografi,klimatologi},
  language     = {eng},
  pages        = {106},
  publisher    = {Lund University Press},
  school       = {Lund University},
  title        = {Spatial Variation in Near-Ground Radiation and Low Temperature - Interactions with Forest Vegetation},
  year         = {1997},
}