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Geophysical Applications of Vegetation Modeling

Kaplan, Jed O LU (2001)
Abstract (Swedish)
Popular Abstract in Swedish

Avhandlingen beskriver utvecklingen och utvalda tillämpningar av en global vegetationsmodell, BIOME4. Modellen kan appliceras på frågeställningar kring vegetationsfördelning och klimat på höga latituder, produktion av spårgaser, och isotopers biogeokemi. Den demonstrerar hur en teoretisk modell, baserad på växtfysiologins och ekologins principer, kan tillämpas på interdisciplinära problem vilka inte kan angripas på ett adekvat sätt genom direkta observationer eller experiment. Arbetet är relevant för förståelsen av återkopplingsmekanismer mellan biosfären och klimatet samt för hur den terrestra biosfären potentiellt kan reagera på förändringar i klimatet.



BIOME4 simulerar... (More)
Popular Abstract in Swedish

Avhandlingen beskriver utvecklingen och utvalda tillämpningar av en global vegetationsmodell, BIOME4. Modellen kan appliceras på frågeställningar kring vegetationsfördelning och klimat på höga latituder, produktion av spårgaser, och isotopers biogeokemi. Den demonstrerar hur en teoretisk modell, baserad på växtfysiologins och ekologins principer, kan tillämpas på interdisciplinära problem vilka inte kan angripas på ett adekvat sätt genom direkta observationer eller experiment. Arbetet är relevant för förståelsen av återkopplingsmekanismer mellan biosfären och klimatet samt för hur den terrestra biosfären potentiellt kan reagera på förändringar i klimatet.



BIOME4 simulerar fördelningen av 15 biom på höga latituder, inklusive fem olika typer av tundravegetation. För nutiden används observerat klimat i simuleringarna och för den senaste istiden (LGM, Last Glacial Maximum, ca. 21 000 år före idag), mitten av Holocene (ca. 6000 år före idag) och ett "växthusscenario" för år 2100 används resultat från generella cirkulationsmodeller av klimatet (GCM, General Circulation Model). Simuleringarna av LGM visar en markant ökning av områden med graminoid och örtdominerad tundravegetation, vilket även är den dominerande tendensen i paleodata. Denna vegetationstyp har ingen utbredd modern motsvarighet; den gynnades av det kalla, torra klimatet och kunde underhålla stora populationer av mammutar. Simuleringar av en period i mitten av Holocene indikerar att den Arktiska trädgränsen försköts asymmetrisk något mot norr jämfört med dagens förhållanden, med störst utvidgning i de centrala delarna av Sibirien (upp till 300 km), och liten till ingen förändring på den Västra Hemisfären. Detta resultat stämmer väl överens med pollen- och megafossildata från samma tidsperiod. Skillnader i uppvärmning av kontinenterna, som ett resultat av ökad solinstrålning på höga latituder, antas vara orsaken till denna asymmetri. Vegetationsförändringarna i 2100-projektionen, vilken antar att koncentrationen av växthusgaser i atmosfären fortsätter att öka exponentiellt, är mer radikala än de simulerade förändringarna under Holocene. Den årliga globala uppvärmningspotentialen orsakad av GHGs leder till en ökning av både sommartemperaturerna och de årliga temperaturerna på höga latituder med upp till den dubbla avvikelsen för Holocene. Den potentiella förskjutningen av trädgränsen och biomförändringarna i vår simulering blir dock troligtvis inte realiserade inom 100 år, på grund av den tid som behövs för migration och etablering av nya vegetationstyper.



Den nutida potentiella arealen av naturliga våtmarker simulerades av BIOME4 till 11.0 x 10<sup>6</sup> km<sup>2</sup>. Detta värde är högre än andra uppskattningar, men det inkluderar även små (< 50 km<sup>2</sup>) och säsongsberoende våtmarker som inte har inkluderats i tidigare undersökningar. Våtmarkerna simulerades till att vara en källa till methan (CH<sub>4</sub>) motsvarande 140 Tg yr<sup>-1</sup>. Under LGM ökade den simulerade våtmarksarealen med 15%, men CH<sub>4</sub>-emissionen var 24% lägre än idag. Denna simulerade reduktion av CH<sub>4</sub>-källan beror på substratbegränsning orsakad av låg atmosfärskoncentration av CO<sub>2</sub> under LGM. Den i iskärnor uppmätta 100-procentiga ökningen av koncentrationen av CH<sub>4</sub> i atmosfären mellan LGM och det förindustriella Holocene är inte nödvändigtvis enbart ett resultat av förändringar i CH<sub>4</sub>-källans styrka, eftersom andra spårgaser påverkar den atmosfäriska CH<sub>4</sub>-sänkan.



Sammansättningen av stabila isotoper av kol i den terrestra biosfären simulerades av BIOME4 och jämfördes med mätningar på blad- ekosystem- och troposfärsnivå. Modellens simuleringar korrelerar inom en standardavvikelse mot uppmätta medelvärden på en skala av vegetationens funktionella grupper (PFT, Plant Functional Type) och på biomnivå, samt även för sex stycken stationer på Norra Hemisfären där koldioxid (CO<sub>2</sub>) moniterats. Global diskriminering av kolisotoper i den terrestra biosfären var i medeltal 18.6‰ för potentiellt naturlig vegetation och 18.1‰ då hänsyn togs till agrikulturell markanvändning. Dessa simulerade värden är något högre än tidigare uppskattningar, men de är förenliga med uppmätta värden. Denna information är viktig för tolkningen av nutida atmosfäriska observationer av kolkällor och kolsänkor på land och i oceanerna. (Less)
Abstract
This thesis describes the development and selected applications of a global vegetation model, BIOME4. The model is applied to problems in high-latitude vegetation distribution and climate, trace gas production, and isotope biogeochemistry. It demonstrates how a modeling approach, based on principles of plant physiology and ecology, can be applied to interdisciplinary problems that cannot be adequately addressed by direct observations or experiments. The work is relevant to understanding the potential effects of climate change on the terrestrial biosphere and the feedbacks between the biosphere and climate.



BIOME4 simulates the distribution of 15 high-latitude biomes, including five tundra vegetation types, for the... (More)
This thesis describes the development and selected applications of a global vegetation model, BIOME4. The model is applied to problems in high-latitude vegetation distribution and climate, trace gas production, and isotope biogeochemistry. It demonstrates how a modeling approach, based on principles of plant physiology and ecology, can be applied to interdisciplinary problems that cannot be adequately addressed by direct observations or experiments. The work is relevant to understanding the potential effects of climate change on the terrestrial biosphere and the feedbacks between the biosphere and climate.



BIOME4 simulates the distribution of 15 high-latitude biomes, including five tundra vegetation types, for the present day using observed climate, and the LGM, mid-Holocene, and a "greenhouse" scenario for 2100 using the output of GCMs. In the LGM simulations, the high-latitudes show a marked increase in the area of graminoid and forb tundra, which is also the predominant feature in the paleodata. This vegetation has no widespread modern analog; it was favored by the cold, dry climate, and supported large mammoth populations. Mid-Holocene simulations indicate a modest, asymmetrical northward advance of the Arctic treeline compared to present, with greatest extension in central Siberia (up to 300 km), and little to no change in the Western Hemisphere. This result is in good agreement with pollen and megafossil data from the same period. Differential warming of the continents in response to increased high-latitude solar radiation is hypothesized to account for the asymmetry. Vegetation changes in the 2100 projection, which assumes a continued exponential increase in atmospheric GHG concentrations, are more radical than those simulated for the mid-Holocene. The year-round forcing due to GHGs increases both summertime and annual temperatures in the high latitudes by up to double the mid-Holocene anomaly. However the potential treeline advances and biome shifts in our simulation are unlikely to be realized within 100 years, because of the time required for migration and establishment of new vegetation types.



Potential natural wetland area for the present day was simulated by BIOME4 as 11.0 x 10<sup>6</sup> km<sup>2</sup>. This value is higher than other estimates but includes small (< 50 km<sup>2</sup>) and seasonal wetlands which have not been included in previous surveys. The wetland CH<sub>4</sub> source was simulated as 140 Tg yr<sup>-1</sup>. At the LGM, simulated wetland area was increased by 15% but CH<sub>4</sub> emissions were 24% less than the present-day. The simulated reduction in the CH<sub>4</sub> source is due to substrate limitation induced by low atmospheric CO<sub>2</sub> concentrations at the LGM. The 100% increase in atmospheric CH<sub>4</sub> concentrations measured in ice cores between the LGM and the preindustrial Holocene may not be due to changes in CH<sub>4</sub> source strength alone, as other trace gases influence the atmospheric CH<sub>4</sub> sink.



The stable carbon isotope composition of the terrestrial biosphere was simulated by BIOME4 and compared to measurements at the leaf, ecosystem and troposphere scales. Model simulations are correlated within one standard deviation to measured means at the PFT and biome scales, and at six Northern Hemisphere CO<sub>2</sub> monitoring stations. Global carbon isotope discrimination in the terrestrial biosphere averaged 18.6‰ for potential natural vegetation and 18.1‰ when an agricultural land-use mask was applied. These simulated values are slightly higher than previous estimates, but consistent with measurements. This information is important for the interpretation of contemporary atmospheric observations in terms of carbon sources and sinks on land and in the ocean. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Prof Street-Perrott, F. Alayne, University of Wales Swansea
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Environmental chemistry, Växtbiokemi, Plant biochemistry, CH4, CO2, stable isotopes, carbon cycle, wetland, ice core, methane, Holocene, mammoths, tundra, ice age, LGM, biogeography, biome, biogeochemistry, Vegetation model, Miljökemi, Physical geography, geomorphology, pedology, cartography, climatology, Fysisk geografi, geomorfologi, marklära, kartografi, klimatologi
pages
128 pages
publisher
Max Planck Institute for Biogeochemistry Postfach 10 01 64D-07701 Jena Germany
defense location
Blå hallen, Ecology Building, Lund University
defense date
2001-03-09 10:00
external identifiers
  • Other:ISRN: SE-LUNBDS/NBBE-01/1062+128pp
ISBN
91-7874-089-4
language
Other
LU publication?
yes
id
3bfcb2f2-dec3-40a3-a6d3-8764f660ce56 (old id 41309)
alternative location
http://infoscience.epfl.ch/record/136645/files/Kaplan_2001.pdf?version=1
date added to LUP
2007-07-31 11:35:03
date last changed
2016-09-19 08:45:11
@misc{3bfcb2f2-dec3-40a3-a6d3-8764f660ce56,
  abstract     = {This thesis describes the development and selected applications of a global vegetation model, BIOME4. The model is applied to problems in high-latitude vegetation distribution and climate, trace gas production, and isotope biogeochemistry. It demonstrates how a modeling approach, based on principles of plant physiology and ecology, can be applied to interdisciplinary problems that cannot be adequately addressed by direct observations or experiments. The work is relevant to understanding the potential effects of climate change on the terrestrial biosphere and the feedbacks between the biosphere and climate.<br/><br>
<br/><br>
BIOME4 simulates the distribution of 15 high-latitude biomes, including five tundra vegetation types, for the present day using observed climate, and the LGM, mid-Holocene, and a "greenhouse" scenario for 2100 using the output of GCMs. In the LGM simulations, the high-latitudes show a marked increase in the area of graminoid and forb tundra, which is also the predominant feature in the paleodata. This vegetation has no widespread modern analog; it was favored by the cold, dry climate, and supported large mammoth populations. Mid-Holocene simulations indicate a modest, asymmetrical northward advance of the Arctic treeline compared to present, with greatest extension in central Siberia (up to 300 km), and little to no change in the Western Hemisphere. This result is in good agreement with pollen and megafossil data from the same period. Differential warming of the continents in response to increased high-latitude solar radiation is hypothesized to account for the asymmetry. Vegetation changes in the 2100 projection, which assumes a continued exponential increase in atmospheric GHG concentrations, are more radical than those simulated for the mid-Holocene. The year-round forcing due to GHGs increases both summertime and annual temperatures in the high latitudes by up to double the mid-Holocene anomaly. However the potential treeline advances and biome shifts in our simulation are unlikely to be realized within 100 years, because of the time required for migration and establishment of new vegetation types.<br/><br>
<br/><br>
Potential natural wetland area for the present day was simulated by BIOME4 as 11.0 x 10&lt;sup&gt;6&lt;/sup&gt; km&lt;sup&gt;2&lt;/sup&gt;. This value is higher than other estimates but includes small (&lt; 50 km&lt;sup&gt;2&lt;/sup&gt;) and seasonal wetlands which have not been included in previous surveys. The wetland CH&lt;sub&gt;4&lt;/sub&gt; source was simulated as 140 Tg yr&lt;sup&gt;-1&lt;/sup&gt;. At the LGM, simulated wetland area was increased by 15% but CH&lt;sub&gt;4&lt;/sub&gt; emissions were 24% less than the present-day. The simulated reduction in the CH&lt;sub&gt;4&lt;/sub&gt; source is due to substrate limitation induced by low atmospheric CO&lt;sub&gt;2&lt;/sub&gt; concentrations at the LGM. The 100% increase in atmospheric CH&lt;sub&gt;4&lt;/sub&gt; concentrations measured in ice cores between the LGM and the preindustrial Holocene may not be due to changes in CH&lt;sub&gt;4&lt;/sub&gt; source strength alone, as other trace gases influence the atmospheric CH&lt;sub&gt;4&lt;/sub&gt; sink.<br/><br>
<br/><br>
The stable carbon isotope composition of the terrestrial biosphere was simulated by BIOME4 and compared to measurements at the leaf, ecosystem and troposphere scales. Model simulations are correlated within one standard deviation to measured means at the PFT and biome scales, and at six Northern Hemisphere CO&lt;sub&gt;2&lt;/sub&gt; monitoring stations. Global carbon isotope discrimination in the terrestrial biosphere averaged 18.6‰ for potential natural vegetation and 18.1‰ when an agricultural land-use mask was applied. These simulated values are slightly higher than previous estimates, but consistent with measurements. This information is important for the interpretation of contemporary atmospheric observations in terms of carbon sources and sinks on land and in the ocean.},
  author       = {Kaplan, Jed O},
  isbn         = {91-7874-089-4},
  keyword      = {Environmental chemistry,Växtbiokemi,Plant biochemistry,CH4,CO2,stable isotopes,carbon cycle,wetland,ice core,methane,Holocene,mammoths,tundra,ice age,LGM,biogeography,biome,biogeochemistry,Vegetation model,Miljökemi,Physical geography,geomorphology,pedology,cartography,climatology,Fysisk geografi,geomorfologi,marklära,kartografi,klimatologi},
  language     = {mis},
  pages        = {128},
  publisher    = {ARRAY(0x870b140)},
  title        = {Geophysical Applications of Vegetation Modeling},
  year         = {2001},
}