Groundwater decline and tree change in floodplain landscapes: identifying non-linear threshold responses in canopy condition

Kath, J. and Reardon-Smith, K. and Le Brocque, A. F. and Dyer, F. J. and Dafny, E. and Fritz, L. and Batterham, M. (2014) Groundwater decline and tree change in floodplain landscapes: identifying non-linear threshold responses in canopy condition. Global Ecology and Conservation, 2. pp. 148-160.

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Abstract

Groundwater decline is widespread, yet its implications for natural systems are poorly understood. Previous research has revealed links between groundwater depth and tree
condition; however, critical thresholds which might indicate ecological 'tipping points' associated with rapid and potentially irreversible change have been difficult to quantify. This study collated data for two dominant floodplain species, Eucalyptus camaldulensis (river
red gum) and E. populnea (poplar box) from 118 sites in eastern Australia where significant groundwater decline has occurred. Boosted regression trees, quantile regression and
Threshold Indicator Taxa Analysis were used to investigate the relationship between tree condition and groundwater depth. Distinct non-linear responses were found, with groundwater depth thresholds identified in the range from 12.1m to 22.6m for E. camaldulensis and 12.6m to 26.6m for E. populnea beyond which canopy condition declined abruptly.
Non-linear threshold responses in canopy condition in these species may be linked to rooting depth, with chronic groundwater decline decoupling trees from deep soil moisture
resources. The quantification of groundwater depth thresholds is likely to be critical for management aimed at conserving groundwater dependent biodiversity. Identifying
thresholds will be important in regions where water extraction and drying climates may contribute to further groundwater decline.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: © 2014 The Authors. This publication is copyright. It may be reproduced in whole or in part for the purposes of study, research, or review, but is subject to the inclusion of an acknowledgment of the source. Under a Creative Commons license.
Faculty / Department / School: No Faculty
Date Deposited: 24 Nov 2014 05:15
Last Modified: 18 Dec 2017 06:12
Uncontrolled Keywords: canopy condition; dieback; drought; tipping point; ecological threshold; groundwater dependent ecosystems
Fields of Research : 05 Environmental Sciences > 0501 Ecological Applications > 050104 Landscape Ecology
05 Environmental Sciences > 0502 Environmental Science and Management > 050206 Environmental Monitoring
05 Environmental Sciences > 0501 Ecological Applications > 050101 Ecological Impacts of Climate Change
Socio-Economic Objective: D Environment > 96 Environment > 9613 Remnant Vegetation and Protected Conservation Areas > 961305 Remnant Vegetation and Protected Conservation Areas in Farmland, Arable Cropland and Permanent Cropland Environments
Identification Number or DOI: 10.1016/j.gecco.2014.09.002
URI: http://eprints.usq.edu.au/id/eprint/26305

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