Schwendenmann, LuitgardYang, Siqi2022-09-052022-09-052022https://hdl.handle.net/2292/61024Kauri dieback is a disease caused by a oomycete called Phytophthora agathidicida. Phytophthora agathidicida is a soil-borne pathogen and infects kauri roots. Kauri dieback results in yellowing of leaves, thinning of the canopy, dieback and mortality. This study investigated (1) soil characteristics and decomposition rates in kauri dominated forests affected by Phytophthora agathidicida, (2) the difference in soil characteristics and decomposition between kauri and non kauri trees, (3) the relationships between soil characteristics and decomposition. The study was conducted in four plots in the Waitākere Ranges Regional Park. Based on visual health symptoms the plots were separated into asymptomatic and symptomatic plots. Decomposition (stabilization factor S and decomposition constant k) was quantified using the Tea Bag Index method using standard green tea and rooibos tea bags. Tea bags were placed in the field from May to November 2021. The S value of kauri in symptomatic plots (0.1321) was significantly lower than that of the asymptomatic (0.1518) plots. In contrast, the decomposition constant k did not differ. The S value of non kauri trees (0.1688) was significantly higher than kauri (0.1206), which may be due to the lower pH of kauri. Soil carbon and nitrogen concentration were the main factors influencing S. Further, S was driven by soil temperature and moisture. Understanding the effects of pathogens on kauri forest litter stability and decomposition rates is critical for forest ecosystem processes and future management and treatment options.Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated.https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htmhttp://creativecommons.org/licenses/by-nc-sa/3.0/nz/Thesis2022-07-26Copyright: the authorhttp://purl.org/eprint/accessRights/OpenAccess