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Components of ecosystem evaporation in a temperate coniferous rainforest, with canopy transpiration scaled using sapwood density
Author(s) -
Barbour M. M.,
Hunt J. E.,
Walcroft A. S.,
Rogers G. N. D.,
McSeveny T. M.,
Whitehead D.
Publication year - 2005
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2004.01257.x
Subject(s) - transpiration , eddy covariance , canopy , environmental science , temperate rainforest , canopy conductance , understory , leaf area index , rainforest , ecosystem , atmospheric sciences , evapotranspiration , forest floor , tropical rainforest , hydrology (agriculture) , vapour pressure deficit , ecology , botany , soil science , biology , photosynthesis , soil water , geology , geotechnical engineering
Summary• Here we develop and test a method to scale sap velocity measurements from individual trees to canopy transpiration ( E c ) in a low‐productivity, old‐growth rainforest dominated by the conifer Dacrydium cupressinum . Further, E c as a component of the ecosystem water balance is quantified in relation to forest floor evaporation rates and measurements of ecosystem evaporation using eddy covariance ( E eco ) in conditions when the canopy was dry and partly wet. • Thermal dissipation probes were used to measure sap velocity of individual trees, and scaled to transpiration at the canopy level by dividing trees into classes based on sapwood density and canopy position (sheltered or exposed). • When compared with ecosystem eddy covariance measurements, E c accounted for 51% of E eco on dry days, and 22% of E eco on wet days. • Low transpiration rates, and significant contributions to E eco from wet canopy evaporation and understorey transpiration (35%) and forest floor evaporation (25%), were attributable to the unique characteristics of the forest: in particular, high rainfall, low leaf area index, low stomatal conductance and low productivity associated with severe nutrient limitation.