Pasture to wetland reconversion: Analysis of soil organic carbon profiles and stocks

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dc.contributor.advisor Mitchell, N en Ezeta Ramos, Gabriela en 2011-02-24T00:20:37Z en 2011 en
dc.identifier.uri en
dc.description Full text is available to authenticated members of The University of Auckland only. en
dc.description.abstract The main objective of this project was to measure organic carbon content in these wetland soils in order to contribute to a full carbon balance of the Estate. For this purpose, soils with a percentage of organic carbon over 10% were considered organic soils while soils with less that 5% organic matter were within the mineral soil category. The results show that the dune wetland, which has been in the process of restoration for more than 6 years, presented concentrations of organic carbon above 10% throughout the 105cm profile. The central wetland system soils had 5-10% organic carbon and were considered recovering wetland soils, while the estuary wetland only had above 5% organic carbon on the first 5cm of soil. Using this data carbon densities were estimated to be 230.6tC/ha for the dune wetland, 120.4tC/ha for the estuary wetland and 128tC/ha for the central wetland on the first 30 cm of soil. On the other hand, the national average of soil organic carbon density in natural wetland soils is of 104.6tC/ha for the same depth. This discrepancy might be explained by the lack of field data on wetland soils, highlighting the importance for further research on the topic. Moreover, the ongoing monitoring of these sites is recommended because the effect of restoration on changes in soil organic carbon concentrations could be quantified. The results also demonstrated that methods used for mineral soil sampling do not apply to wetlands. For example, sampling to a 30 cm depth underestimates organic carbon densities and stocks. For instance, the dune wetland had the highest concentrations of organic carbon on the 45-60cm and the central wetlands on the 75-90cm layer. Hence, this study aimed to develop a method for more accurate carbon stock estimations and compared two different methods. As opposed to the traditional method, the proposed method considers wetland shape (i.e. shallower on the border than in the middle) and uses the reducing surface areas for each layer derived from a model to calculate carbon stocks. The results show that the traditional way of calculating overestimates carbon stocks for wetlands. However, the method suggested in this study could be improved by adding more organic soil depth data to the model to avoid bias towards sampled sites. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof Masters Thesis - University of Auckland en
dc.relation.isreferencedby UoA99215505214002091 en
dc.rights Restricted Item. Available to authenticated members of The University of Auckland. en
dc.rights.uri en
dc.title Pasture to wetland reconversion: Analysis of soil organic carbon profiles and stocks en
dc.type Thesis en Environmental Science en The University of Auckland en Masters en
dc.rights.holder Copyright: the author en
pubs.elements-id 206472 en
pubs.record-created-at-source-date 2011-02-24 en

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