Thursday, August 31, 2023

Some papers that discuss tree allometry to obtain biomass and sapwood cross sectional area

In order to accurately determine the water budget of trees (see also yesterday's post), it is crucial to establish a connection between the quantity of sapwood and the transpiration rate from the leaves. One essential factor in this process is obtaining accurate measurements of the sapwood cross-sectional areas (CSA). However, it is important to note that these CSA measurements can vary significantly from one plant to another. Acquiring this data can be challenging, and as a result, researchers have conducted studies aiming to establish allometric relationships as a means to estimate these measurements. To assist me in finding relevant literature on this topic, I reached out to my colleague involved in the WATERSTEM project. Below, you will find the literature they recommended.


Berry, Z. Carter, Nathaniel Looker, Friso Holwerda, León Rodrigo Gómez Aguilar, Perla Ortiz Colin, Teresa González Martínez, and Heidi Asbjornsen. 2018. “Why Size Matters: The Interactive Influences of Tree Diameter Distribution and Sap Flow Parameters on Upscaled Transpiration.” Tree Physiology 38 (2): 263–75.

Kubota, Mitsumasa, John Tenhunen, Reiner Zimmermann, Markus Schmidt, Samuel Adiku, and Yoshitaka Kakubari. n.d. “Influences of Environmental Factors on the Radial Profile of Sap Flux Density in Fagus Crenata Growing at Different Elevations in the Naeba.”

Lüttschwager, Dietmar, and Hubert Jochheim. 2020. “Drought Primarily Reduces Canopy Transpiration of Exposed Beech Trees and Decreases the Share of Water Uptake from Deeper Soil Layers.” Forests, Trees and Livelihoods 11 (5): 537.

Lüttschwager, Dietmar, and Rainer Remus. 2007. “Radial Distribution of Sap Flux Density in Trunks of a Mature Beech Stand.” Annals of Forest Science 64 (4): 431–38.

Niccoli, Francesco, Arturo Pacheco-Solana, Sylvain Delzon, Jerzy Piotr Kabala, Shahla Asgharinia, Simona Castaldi, Riccardo Valentini, and Giovanna Battipaglia. 2023. “Effects of Wildfire on Growth, Transpiration and Hydraulic Properties of Pinus Pinaster Aiton Forest.” Dendrochronologia 79 (126086): 126086.

Petrík, Peter, Ina Zavadilová, Ladislav Šigut, Natalia Kowalska, Anja Petek-Petrik, Justyna Szatniewska, Georg Jocher, and Marian Pavelka. 2022. “Impact of Environmental Conditions and Seasonality on Ecosystem Transpiration and Evapotranspiration Partitioning (T/ET Ratio) of Pure European Beech Forest.” WATER 14 (19): 3015.

Thurner, Martin, Christian Beer, Thomas Crowther, Daniel Falster, Stefano Manzoni, Anatoly Prokushkin, and Ernst-Detlef Schulze. 2019. “Sapwood Biomass Carbon in Northern Boreal and Temperate Forests.” Global Ecology and Biogeography: A Journal of Macroecology 28 (5): 640–60.

Wednesday, August 30, 2023

A Rosetta stone for connecting the various forms of the Darcy-Buckingham law use in Hydrology and Plants Physiology

The information presented here is derived from the study conducted by Carminati and Javaux in 2020, which aimed to provide insights into plant hydraulics. Carminati referred to the work of Kroeber et al. in 2014, who conducted extensive measurements on a variety of plants and reported their data. However, a discrepancy arises between hydrologists and plant physiologists in the units used to measure hydraulic conductivity. While hydrologists measure it in meters per second (m/s), plant physiologists measure it in kilograms per meter per Pascal second [Kg m/(Pa s)].

In their study, Kroeber et al. reported conductivity per unit area, denoted as Kk, measured in kilograms per meter per Pascal second [Kg/(m Pa s)]. This unit might seem unfamiliar or obscure. To bridge the gap between my background and the new papers, Carminati and Javaux provide a clue. They suggest that the relationship between Kk and the commonly used hydraulic conductivity, K_w, expressed in centimeters per day (cm/day), can be established using the enigmatic equation K_w = g * 100 * 10^(-6) * 3600 * 24 * Kk. Now, the question arises: Is 'g' referring to the acceleration due to gravity?

So I dedicated a couple of days of my life to build a Rosetta Stone to translate the units and check the coherence of what done. The result is a short paper by me and Concetta D'Amato that you  can find here

For obtaining this I had to walk through the valley of the water potentials expressed in different units, but also this can be interesting for the reader.  

Next step is understand which is the value of the cross section through which the water flow to obtain, at the end, real cubic meter per second or kg per second. 


Carminati, Andrea, and Mathieu Javaux. 2020. “Soil Rather Than Xylem Vulnerability Controls Stomatal Response to Drought.” Trends in Plant Science 25 (9): 868–80.

Kröber, Wenzel, Shouren Zhang, Merten Ehmig, and Helge Bruelheide. 2014. “Linking Xylem Hydraulic Conductivity and Vulnerability to the Leaf Economics Spectrum—A Cross-Species Study of 39 Evergreen and Deciduous Broadleaved Subtropical Tree Species.” PloS One 9 (11): e109211.