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The effects of managed ruminants grazing on the global carbon cycle and greenhouse gas forcing

Lagerstedt, Jakob (2006) In Lunds universitets Naturgeografiska institution - Seminarieuppsatser
Dept of Physical Geography and Ecosystem Science
Abstract (Swedish)
Populärvetenskaplig sammanfattning: Kolcykeln är enkelt uttryckt den globala balansräkningen av kolets (C) förflyttning genom olika sfärer såsom mellan atmosfären och biosfären, således är kolcykeln av stor betydelse för mänsklighetens existens. Exempelvis har atmosfäriska koncentrationer av koldioxid (CO2) och metan (CH4) ökat de senaste 200 hundra åren på grund av mänskliga aktiviteter (till stor del en förflyttning av kol från olika sfärer till atmosfären direkt eller indirekt via olika mekanismer såsom t.ex. förbränning av olja). Studiet av kols rörelser genom olika sfärer är intressant av många anledningar, men främst för att skapa bättre förståelse kring växthusgasernas (koldioxid och metan med flera) koncentrationer och dess... (More)
Populärvetenskaplig sammanfattning: Kolcykeln är enkelt uttryckt den globala balansräkningen av kolets (C) förflyttning genom olika sfärer såsom mellan atmosfären och biosfären, således är kolcykeln av stor betydelse för mänsklighetens existens. Exempelvis har atmosfäriska koncentrationer av koldioxid (CO2) och metan (CH4) ökat de senaste 200 hundra åren på grund av mänskliga aktiviteter (till stor del en förflyttning av kol från olika sfärer till atmosfären direkt eller indirekt via olika mekanismer såsom t.ex. förbränning av olja). Studiet av kols rörelser genom olika sfärer är intressant av många anledningar, men främst för att skapa bättre förståelse kring växthusgasernas (koldioxid och metan med flera) koncentrationer och dess framtida inverkan.

Boskap i form av tama idisslare (till exempel kor, får och getter) översteg 1996 två miljarder individer och hade då ökat sedan 70-talet med omkring 30 %. Då idisslare både tar up kol ur biosfären och avger metan till atmosfären genom deras konsumtion av gräs kan man med grund av deras stora antal anta att de har en betydande inverkan på den globala kolcykeln.

Det finns många modeller som syftar att skatta kolcykeln och dess interaktion med framtida klimatförändringar. LPJ-DVGM är en sådan modell som är väl dokumenterad och ackrediterad. Tyvärr räknar inte senaste versionen av LPJ-DVGM med tamboskapens eventuella inverkan. Därför ämnar detta examensarbete skapa en metod för hur tamboskapens inverkan på kolcykeln kan innefattas i LPJ-DVGM modellen. Samt ge svar på frågan om tamboskapens eventuella effekter är stora nog på den globala kolcykeln för att göra ansträngningen värd mödan.

Resultaten föreslår att den globala populationen av tamboskap har en betydande påverkan på kolcykeln. Global NPP visar en lägre produktivitet i ordningen kring ca 5 % när tamboskap tas med i beräkningen, detta resultat är i linje med andra studier. Vidare skattar modellen med god noggrannhet metan utsläppen från tamboskapen. Det senare resultatet används för att validera modellen och resultatet ger gott hopp att modellens metod är sund. (Less)
Abstract
Carbon is central to our existence. It plays a fundamental role in the carbon cycle.
Atmospheric concentrations of carbon dioxide (CO2) and methane (CH4) have been
increasing for about two centuries as a result of human activities. The need to understand
how carbon cycles through the Earth-system is important for a variety of reasons, but
mainly in order to assess the effects of these rising greenhouse gas concentrations and to
project future concentrations and effects.
The world population of larger domestic grazing animals (i.e. cattle, goats and sheep)
totaled around 2 billion in 1996, and has steadily increase since the 1970s by about 30%.
Due in part to their large numbers the worlds grazing animals are thought to have an
... (More)
Carbon is central to our existence. It plays a fundamental role in the carbon cycle.
Atmospheric concentrations of carbon dioxide (CO2) and methane (CH4) have been
increasing for about two centuries as a result of human activities. The need to understand
how carbon cycles through the Earth-system is important for a variety of reasons, but
mainly in order to assess the effects of these rising greenhouse gas concentrations and to
project future concentrations and effects.
The world population of larger domestic grazing animals (i.e. cattle, goats and sheep)
totaled around 2 billion in 1996, and has steadily increase since the 1970s by about 30%.
Due in part to their large numbers the worlds grazing animals are thought to have an
affect on the global carbon cycle.
Many models exist that produce estimates of the carbon cycle and its interaction with
future climate change. One well-documented and reviewed model is termed the LPJDGVM
ecosystem model. However it does not in its current state account for domestic
grazing animals.
Therefore the focus of this thesis will be an attempt to develop a method for
incorporating the effects of grazing animals into the LPJ-DGVM model. Further the
method will be used to test the thesis statement “grazing herbivores exhibit a measurable
impact on the carbon cycle and merits inclusion in carbon cycle models”.
Results suggest that, indeed, the worlds grazing animals can have an effect on the global
carbon cycle and merit inclusion in carbon cycle models. Results for global NPP fluxes
show lower productivity over the studied period of about 5%, which follows the same
trend as other studies. Results for global NEE fluxes are surprising and suggest the
biosphere is acting as a 50% stronger sink when grazing is taken into account. At present
no satisfactory explanation for the somewhat contradictory NEE results has been found.
Although a unverified theory suggests a conceptual flaw in the LPJ-DVGM models
treatment of grassland fires. Nonetheless contradictory results are common in this line of
research, especially in the early stages, and a conclusive search for the mistake can take
months before it yields a valid result. (Less)
Please use this url to cite or link to this publication:
author
Lagerstedt, Jakob
supervisor
organization
alternative title
En modellering av tamboskapens inverkan på den globala kolcykeln
year
type
M2 - Bachelor Degree
subject
keywords
ruminants, ecological modeling, carbon cycle, geography, physical geography, LPJ-DGVM, C++
publication/series
Lunds universitets Naturgeografiska institution - Seminarieuppsatser
report number
132
language
English
id
1955365
date added to LUP
2011-05-12 16:08:05
date last changed
2011-12-13 17:30:29
@misc{1955365,
  abstract     = {Carbon is central to our existence. It plays a fundamental role in the carbon cycle.
Atmospheric concentrations of carbon dioxide (CO2) and methane (CH4) have been
increasing for about two centuries as a result of human activities. The need to understand
how carbon cycles through the Earth-system is important for a variety of reasons, but
mainly in order to assess the effects of these rising greenhouse gas concentrations and to
project future concentrations and effects.
The world population of larger domestic grazing animals (i.e. cattle, goats and sheep)
totaled around 2 billion in 1996, and has steadily increase since the 1970s by about 30%.
Due in part to their large numbers the worlds grazing animals are thought to have an
affect on the global carbon cycle.
Many models exist that produce estimates of the carbon cycle and its interaction with
future climate change. One well-documented and reviewed model is termed the LPJDGVM
ecosystem model. However it does not in its current state account for domestic
grazing animals.
Therefore the focus of this thesis will be an attempt to develop a method for
incorporating the effects of grazing animals into the LPJ-DGVM model. Further the
method will be used to test the thesis statement “grazing herbivores exhibit a measurable
impact on the carbon cycle and merits inclusion in carbon cycle models”.
Results suggest that, indeed, the worlds grazing animals can have an effect on the global
carbon cycle and merit inclusion in carbon cycle models. Results for global NPP fluxes
show lower productivity over the studied period of about 5%, which follows the same
trend as other studies. Results for global NEE fluxes are surprising and suggest the
biosphere is acting as a 50% stronger sink when grazing is taken into account. At present
no satisfactory explanation for the somewhat contradictory NEE results has been found.
Although a unverified theory suggests a conceptual flaw in the LPJ-DVGM models
treatment of grassland fires. Nonetheless contradictory results are common in this line of
research, especially in the early stages, and a conclusive search for the mistake can take
months before it yields a valid result.},
  author       = {Lagerstedt, Jakob},
  keyword      = {ruminants,ecological modeling,carbon cycle,geography,physical geography,LPJ-DGVM,C++},
  language     = {eng},
  note         = {Student Paper},
  series       = {Lunds universitets Naturgeografiska institution - Seminarieuppsatser},
  title        = {The effects of managed ruminants grazing on the global carbon cycle and greenhouse gas forcing},
  year         = {2006},
}