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Production and biodegradability of dissolved organic carbon from dIfferent litter sources

Arellano, Carlos LU (2015) In Student thesis series INES NGEM01 20151
Dept of Physical Geography and Ecosystem Science
Abstract
The movement of carbon on Earth is based on exchange between pools that represent carbon in different physical forms, differing in chemical composition, structure and function. Dissolved organic carbon plays an important role in ecosystems because of its mobility, which can be relatively high in saturated soils, and because it is the most available fraction of organic matter for microorganisms in soil, being particularly active in microbial degradation processes through soil profile. The ability of moving through soil, that DOC has, makes it an essential part of the organic loading to the streams, forming a bridge between the carbon of terrestrial and aquatic systems. However, relatively little is known about the production and fate of DOC... (More)
The movement of carbon on Earth is based on exchange between pools that represent carbon in different physical forms, differing in chemical composition, structure and function. Dissolved organic carbon plays an important role in ecosystems because of its mobility, which can be relatively high in saturated soils, and because it is the most available fraction of organic matter for microorganisms in soil, being particularly active in microbial degradation processes through soil profile. The ability of moving through soil, that DOC has, makes it an essential part of the organic loading to the streams, forming a bridge between the carbon of terrestrial and aquatic systems. However, relatively little is known about the production and fate of DOC from its main source, which is plant organic matter. The correlation between the type of litter and the characteristics of the DOC produced from it represent the knowledge gap that this study aims to fill. The litter from six plant species was used to extract DOC over different extraction periods from one up to forty eight hours. Also, a degradation study on the DOC extracts was performed and the resulting degradation curves were analyzed in relation to the extraction time, percentage of aromaticity and to the nitrogen composition of the litter. The results showed that only in some of the species surveyed the DOC leaching from the wood litter is lower than the one from the leaf litter. Moreover, the DOC aromaticity did not increase over extraction time as was expected, but instead it tended to decrease. The degradation experiment showed an increase in lability until the 16 hours extraction, which was different to the expected pattern of decreasing lability as extraction time increased. Significant differences in DOC leaching rate and lability were also found between evergreen plant litter and summer green plant litter. The differences in production and degradability of the DOC are thus related to a wide range of factors, other than the chemical composition of the litter. Other factors such as physiological variations among species and plant structures appear to play a significant role in the DOC production. The results show that assumptions made in models about DOC production depending only on chemical structure of litter can possibly be improved by including physiological differences among species and morphological structures. (Less)
Popular Abstract
The threat that climate change represents to mankind is now closer than ever. The carbon cycle, which is the circulation of carbon through earth, gives us the clue to identify how climate change is produced. It might be surprising to know that the falling leaves during autumn, that announce us the end of the sunny days of the summer, play an important role on climate change. The way in which local processes such as falling leaves and twigs, so called plant litter, can have a global effect is because of the chemical compounds that are released from them when they fall. These compounds contain high amounts of carbon, being a key feature in the carbon cycle. The topic gets more interesting once we take into account that the leached chemical... (More)
The threat that climate change represents to mankind is now closer than ever. The carbon cycle, which is the circulation of carbon through earth, gives us the clue to identify how climate change is produced. It might be surprising to know that the falling leaves during autumn, that announce us the end of the sunny days of the summer, play an important role on climate change. The way in which local processes such as falling leaves and twigs, so called plant litter, can have a global effect is because of the chemical compounds that are released from them when they fall. These compounds contain high amounts of carbon, being a key feature in the carbon cycle. The topic gets more interesting once we take into account that the leached chemical compounds differ depending on wide variety of factors, such as plant species and plant part where the litter comes from.
My thesis project was focused on investigate the amount of compounds leached from different plant litter, as well as its chemical characteristics. Patterns showed in the results suggest links between the type of compounds leached and the type of litter. Links such as having more compounds leached from leaves than from wood and more from summer green trees leaves than from evergreen trees leaves were highlighted. Also, the chemical characteristics of the leached compounds change over time depending on how long the litter has been exposed to the environment. In conclusion, knowing the characteristics and the behavior of the leached compounds from litter is an important tool in order to improve our understanding on the earth system. Understanding the earth processes is crucial in order to identify the causes, effects and possible solutions to climate change. (Less)
Please use this url to cite or link to this publication:
author
Arellano, Carlos LU
supervisor
organization
course
NGEM01 20151
year
type
H2 - Master's Degree (Two Years)
subject
keywords
biogeochemical cycles, physical geography and ecosystem analysis, dissolved organic carbon, carbon cycle, soil biogeochemistry
publication/series
Student thesis series INES
report number
363
language
English
id
8163240
date added to LUP
2015-11-04 14:06:19
date last changed
2015-11-04 14:06:19
@misc{8163240,
  abstract     = {The movement of carbon on Earth is based on exchange between pools that represent carbon in different physical forms, differing in chemical composition, structure and function. Dissolved organic carbon plays an important role in ecosystems because of its mobility, which can be relatively high in saturated soils, and because it is the most available fraction of organic matter for microorganisms in soil, being particularly active in microbial degradation processes through soil profile. The ability of moving through soil, that DOC has, makes it an essential part of the organic loading to the streams, forming a bridge between the carbon of terrestrial and aquatic systems. However, relatively little is known about the production and fate of DOC from its main source, which is plant organic matter. The correlation between the type of litter and the characteristics of the DOC produced from it represent the knowledge gap that this study aims to fill. The litter from six plant species was used to extract DOC over different extraction periods from one up to forty eight hours. Also, a degradation study on the DOC extracts was performed and the resulting degradation curves were analyzed in relation to the extraction time, percentage of aromaticity and to the nitrogen composition of the litter. The results showed that only in some of the species surveyed the DOC leaching from the wood litter is lower than the one from the leaf litter. Moreover, the DOC aromaticity did not increase over extraction time as was expected, but instead it tended to decrease. The degradation experiment showed an increase in lability until the 16 hours extraction, which was different to the expected pattern of decreasing lability as extraction time increased. Significant differences in DOC leaching rate and lability were also found between evergreen plant litter and summer green plant litter. The differences in production and degradability of the DOC are thus related to a wide range of factors, other than the chemical composition of the litter. Other factors such as physiological variations among species and plant structures appear to play a significant role in the DOC production. The results show that assumptions made in models about DOC production depending only on chemical structure of litter can possibly be improved by including physiological differences among species and morphological structures.},
  author       = {Arellano, Carlos},
  keyword      = {biogeochemical cycles,physical geography and ecosystem analysis,dissolved organic carbon,carbon cycle,soil biogeochemistry},
  language     = {eng},
  note         = {Student Paper},
  series       = {Student thesis series INES},
  title        = {Production and biodegradability of dissolved organic carbon from dIfferent litter sources},
  year         = {2015},
}