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Trends in evapotranspiration and streamflow following wildfire in resprouting eucalypt forests

Citation

Nolan, RH and Lane, PNJ and Benyon, RG and Bradstock, RA and Mitchell, PJ, Trends in evapotranspiration and streamflow following wildfire in resprouting eucalypt forests, Journal of Hydrology, 524 pp. 614-624. ISSN 0022-1694 (2017) [Refereed Article]

Copyright Statement

Copyright 2015 Elsevier B.V.

DOI: doi:10.1016/j.jhydrol.2015.02.045

Abstract

The objective of this study was to estimate the recovery trajectory of evapotranspiration (Et) and streamflow (Q) in resprouting forested catchments following wildfire. Recovery dynamics were assessed in mixed species eucalypt forests in south-eastern Australia which recover from disturbance largely via vegetative resprouting, and to a lesser degree, via seedling recruitment. Changes in Et were evaluated in two ways. Firstly, we developed semi-empirical models of post-fire Et following moderate and high severity wildfire. These models were based on datasets of plot-scale Et, measured within five years post-fire, and published literature on post-fire changes in vegetation structure. Secondly, we analysed long-term Q records (25years) from a mixed species catchment, including a 1-5year period following a predominately moderate severity wildfire. We found that the overall length of recovery time for Et and Q following wildfire was 8-12years, which is much less than for eucalypt forests recovering via seedlings only. This emphasises the importance of functional responses to fire in forest ecosystems as a key driver of the hydrologic resilience of catchments, with resprouting forest types conferring relatively rapid recovery following disturbance. We also found that the recovery trajectory of post-fire Et was dependent on fire severity. Increased Et and consequent declines in Q occurred following moderate severity fire. In contrast, there was no evidence of increased Et following high severity fire. Based on patterns of long-term Q and rainfall observed in a small mixed species catchment, declines in Q due to increased Et following moderate severity wildfire were of similar magnitude to Q declines driven by a drought that coincided with the fire. We conclude that the coincidence of wildfire with drought exacerbates reductions in Q under moderate severity fire, resulting in greater Q declines. This is due to the enhanced rates of Et, primarily driven by regenerating seedlings and higher rates of transpiration from surviving trees.

Item Details

Item Type:Refereed Article
Keywords:water balance, streamflow elasticity, resilience, disturbance, fire severity
Research Division:Biological Sciences
Research Group:Plant Biology
Research Field:Plant Physiology
Objective Division:Environment
Objective Group:Flora, Fauna and Biodiversity
Objective Field:Forest and Woodlands Flora, Fauna and Biodiversity
Author:Mitchell, PJ (Dr Patrick Mitchell)
ID Code:120058
Year Published:2017
Web of Science® Times Cited:9
Deposited By:Plant Science
Deposited On:2017-08-09
Last Modified:2017-09-20
Downloads:0

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