Whole tree water use: Effects of tree morphology and environmental factors

• Published in: Ecological indicators Vol. 102; pp. 366 - 373
• Main Authors: Tfwala, C.M., Van Rensburg, L.D., Schall, R., Zietsman, P.C., Dlamini, P.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2019
• Subjects: Climatic factors; Transpiration measuring techniques; Tree height and stem diameter; Tree transpiration; Climatic factors; Tree transpiration; Tree height and stem diameter; Transpiration measuring techniques
• ISSN: 1470-160X; 1872-7034
• DOI: 10.1016/j.ecolind.2019.02.054

•Tree height and stem diameter are positively correlated to tree water use.•Environmental factors are secondary to morphological traits as determinants of whole tree water use.•Thermodynamic methods are most commonly used to quantify tree water use. Although tree transpiration (T) studies across multiple spatial scales have been conducted, the synthesis of the driving factors of tree water use, especially for a variety of species under different climatic conditions has not yet been made. This paper analyses T data from 94 published studies conducted in various sites between 1970 and 2016, representing 196 data points to seek relations between morphological traits; tree height (H), diameter at breast height (DBH) and environmental factors; mean annual precipitation (MAP), mean annual temperature (MAT) and altitude (Z) on whole tree water use for 130 species of trees. Techniques used in the studies for T measurement were also analysed. Log transformed T (ln T) varied between 0 and 7.1 L day−1. Univariate correlation and regression analysis revealed that ln T was positively and significantly correlated with H (Spearman correlation coefficient (rs) = 0.55) and DBH (rs = 0.62) at P < 0.1. A weak positive correlation was found between ln T and MAP (rs = 0.16) at P < 0.1. The results further showed that during the study period (1970–2016), 82% of the studies used thermodynamic methods to measure T, in particular thermal heat dissipation probes were used by 60% of the studies, while 21% reported use of heat pulse velocity. The results contribute to a better understanding of T in forest ecosystems, and the factors of control to inform global scale modelling and ecosystem management. Thermodynamic methods, especially thermal heat dissipation probes and heat pulse velocity are the most prevalent techniques used for whole tree T measurement.