Ecological restoration of Wairio Wetland, New Zealand : Effect of flooding on woody vegetation, carbon sequestration and recommendations for future plantings
Fanal, Aurore
Promotor(s) :
Claessens, Hugues
;
Hartley, Stephen
Date of defense : 25-Aug-2017 • Permalink : http://hdl.handle.net/2268.2/3038
Details
Title : | Ecological restoration of Wairio Wetland, New Zealand : Effect of flooding on woody vegetation, carbon sequestration and recommendations for future plantings |
Translated title : | [fr] Restauration écologique du "Wairio Wetland", Nouvelle-Zélande: Impact d'une inondation sur la végétation ligneuse, séquestration carbone et recommandations pour les futures plantations. |
Author : | Fanal, Aurore ![]() |
Date of defense : | 25-Aug-2017 |
Advisor(s) : | Claessens, Hugues ![]() Hartley, Stephen |
Committee's member(s) : | Lejeune, Philippe ![]() Hebert, Jacques ![]() Mahy, Grégory ![]() |
Language : | English |
Number of pages : | 84 |
Keywords : | [fr] Wetland [fr] Restoration [fr] Planting treatments [fr] Planting methods [fr] Freshwater wetland [fr] Flooding [fr] Carbon sequestration [fr] restoration plantings [fr] revegetation [fr] planting treatments [fr] D. dacrydioides [fr] Kahikatea [fr] Totara [fr] Zone humide [fr] restauration [fr] séquestration carbone [fr] inondation [fr] immersion [fr] traitements [fr] plantation [fr] planting map [fr] plantation plan |
Discipline(s) : | Life sciences > Environmental sciences & ecology |
Commentary : | Thesis realized as part of the Wairarapa Moana Restoration Project. |
Funders : | Fonds d'aide à la mobilité de la Fédération Wallonie-Bruxelles (FAME), Université de Liège (Fonds de Mobilité). |
Research unit : | School of Biological Sciences, Victoria University of Wellington |
Name of the research project : | Wairio Wetlan Restoration Project |
Target public : | Researchers Professionals of domain Student |
Institution(s) : | Université de Liège, Liège, Belgique |
Degree: | Master en bioingénieur : gestion des forêts et des espaces naturels, à finalité spécialisée |
Faculty: | Master thesis of the Gembloux Agro-Bio Tech (GxABT) |
Abstract
[en] This thesis analyses the success of plantings in the Wairio Wetland, a 132-ha area of the Wairarapa Moana wetland complex, located in the lower North Island of New Zealand. In 2011, as part of a restoration project, 2,368 native trees of eight different species were planted in a fenced area using various planting methods. These include: the use of weedmats, topsoil removal, herbicide spraying, the planting of nurse trees, and altered spacing distances. The study aims to (1) analyse the effect of treatments on growth and survival after six years, as well as the effect of elevation (related to water level), (2) develop informed planting strategies for future plantings, and (3) estimate the amount of carbon sequestered by trees.
Six years after planting, results show that all species exhibited poor survival rates. An extreme flooding event in 2016 was responsible for a drop in the survival rates of almost all species. The tolerance to low elevations decreased at the same time. As such, elevation was an important predictor of survival. Topsoil scraping and wide spacing between trees positively influenced the survival of some species. However, most trees grew less in scraped soils. The presence of nurse trees and altered spacing distances did not influence the growth of most species. It is estimated that a total of 1.4 tonne of carbon has been sequestered by planted trees. Survival maps were created and used to inform planting plans in adjacent areas. If utilised, 15.7 tonnes of carbon could be sequestered after six years, or 233 tonnes over the entire Wairio restoration block.
This study highlights the need for an efficient weed control method and emphasises the importance of understanding local hydrology before planting. Also, revising the priority services to restore might be necessary to define the best planting zones. Some objectives might be antagonistic, such as the filtration of water run-off from pastoral lands and the restoration of a Dacrycarpus dacrydioides swamp forest providing shelter to native flora and fauna.
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