Latent heat fluxes during two contrasting years from a juvenile plantation established over a waste disposal landscape

JOURNAL OF HYDROLOGY

卷:399

Article

Yunusa, Isa A. M.¹  Fuentes, Sigfredo¹  Palmer, Anthony R.¹  Macinnis-Ng, Catriona M. O.¹  Zeppel, Melanie J. B.¹  Eamus, Derek¹ 

[1] Univ Technol Sydney, Sch Environm Sci, Plant Funct Biol & Climate Change Cluster, Sydney, NSW 2007, Australia

关键词: Bowen ratio;    Drainage;    Juvenile plantation;    Sapflow;    Transpiration;    Land rehabilitation;   

DOI  :  10.1016/j.jhydrol.2010.12.033

来源: Elsevier

【 摘 要 】

Revegetation to restore hydrological function to highly disturbed landscapes used for waste disposal or mining is often constrained by the initial low rates of water-use during the early phases of the developing vegetation. This problem is especially pronounced for revegetation that relies on trees due to their prolonged lead-time to achieve canopy closure. Initial low rates of water-use can however be overcome if a groundcover of quick-growing herbaceous species is planted first. To demonstrate the significance of groundcover in the early phase of revegetation, we undertook an energy balance analysis using the Bowen ratio technique for a juvenile plantation growing over a heavy groundcover of herbaceous species on a waste disposal site in 2006/2007 and 2007/2008. Latent heat flux (lambda E) from the landscape (trees plus groundcover and soil) fluctuated widely between 0.5 and 22 MJ m(-2) d(-1) and accounted for between 60% and 90% of available energy at the site; this percentage exceeded 100% during periods with significant advection. The latent heat emanating from the tree canopy (lambda E-c), derived from sapflow measurements in the trees, accounted for only between 4% and 18% of daily lambda E with the balance arising from the groundcover that intercepted more than 90% of incident solar radiation. The lambda E-c was mostly smaller than the net radiation intercepted by the tree canopy (R-nc) with the excess energy expended by the canopy as sensible heat (H-c), which accounted for up to 18% of bulk sensible heat from the landscape. The lambda E expressed as ET was in excess (114%) of rainfall in the relatively dry first growing (September-May) season, when rainfall was only 87% of the long-term average. It was, however, smaller (80%) than rainfall during the second season, when the annual rainfall was close to the long-term average. We used these data to develop an empirical model for predicting lambda E from soil-water content and the prevailing evaporative demand. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.

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