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Northern Territory University (2002)

The distribution of coarse and fine root biomass in a semi-arid savanna of northern Australia

Allnutt, Michelle

Titre : The distribution of coarse and fine root biomass in a semi-arid savanna of northern Australia

Auteur : Allnutt, Michelle

Université de soutenance : Northern Territory University

Grade : Master of (Tropical) Environmental Management (MTEM) 2002

Résumé
Root distribution of a semi-arid savanna located near Katherine in the Northern Territory was determined. Trenches were excavated between 8 pairs of E. foelscheana (F. Muell.) and fine and coarse roots were sampled ve11ically and horizontally along the trenches. The majority of the total root biomass was located close to the tree stems and in the top 0.5 m of the soil. Coarse roots were distributed as a function of distance from the nearest tree and size of the nearest tree (DBH). Fine roots were found to be most abundant in the first 30 cm of the soil, but there was no correlation between fine roots and distance from nearest tree stem or size of nearest tree. Predicted total root biomass was 35.7 t DM ha-1 , which is a carbon stock of 17.5 t C ha-1. The vast majority (96%) of this was coarse roots, and the fine root biomass was 0.7 t C ha-1. The destructive sampling of this study enabled the development of allomet1ic relationships between the tree size (DBH) and root distribution . These relationships were used to predict carbon stocks at a regional scale. The area occupied by the same vegetation type as the study site (E. foelscheana and E tectijica dominated savanna) is 49,811 km2 . Using the below-ground biomass density (17.5 t C ha-1) and this area, a below-ground carbon storage of approximately 87 Mt C is calculated, a significant storage. This study contributes to research of national significance, because savannas may offer significant potential as a (tradable) carbon sink to offset greenhouse gas emissions (e.g. from fires) ; and managing carbon storage and cycling is an important aspect of maintaining healthy ecosystem function.

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