The watering of tall trees - Embolization and recovery

We can propound a thermo-mechanical understanding of the ascent of sap to the top of tall trees thanks to a comparison between experiments associated with the cohesion-tension theory and the disjoining pressure concept for liquid thin-films. When a segment of xylem is tight-filled with crude sap, the liquid pressure can be negative although the pressure in embolized vessels remains positive. Examples are given that illustrate how embolized vessels can be refilled and why the ascent of sap is possible even in the tallest trees avoiding the problem due to cavitation. However, the maximum height of trees is limited by the stability domain of liquid thin-films.Comment: Extended introduction and additive comments removed from the Journal of Theoretical Biology.22 page

April

From tall trees, The cool moisture rushes To the ground..

The Story of Randa Bayama

With his golden flute pressed between his lips His fingers ready to start dancing on the holes Walked Randa Bayama the snake charmer Under the tall trees in search of the queen cobra..

Habitat Characteristics of the Honey Bee (Apis dorsata), Harvesting Methods of Forest Honey, and Characteristics of Sumbawa Forest Honey in Sumbawa Regency, Indonesia

Sumbawa forest honey is honey produced by Apis dorsata bees. The problem faced is that Apis dorsata bees cannot be cultivated in stup and can only live in tall trees in the forest. This study aimed to determine the characteristics of Apis dorsata bees and Sumbawa forest honey. This research was conducted using a survey method, conducting field observations, interviews with several parties, and documentation. The research was conducted in Sumbawa Regency. The results of the study found that the survival of the Apis dorsata bee was highly dependent on forest sustainability. The taste and color of Sumbawa forest honey depend on the type of food or nectar consumed by Apis dorsata bees. This study concludes that Apis dorsata honey bees cannot be cultivated in stups, because this type of bee can only survive and thrive on tall trees in the forest. Sustainable harvesting techniques are carried out to sustain forest life and Apis dorsata bees. The price of Sumbawa forest honey varies based on its packaging, purity, water content, and distance traveled to collect it

Liquid-solid interaction at nanoscale and its application in vegetal biology

The water ascent in tall trees is subject to controversy: the vegetal biologists debate on the validity of the cohesion-tension theory which considers strong negative pressures in microtubes of xylem carrying the crude sap. This article aims to point out that liquids are submitted at the walls to intermolecular forces inferring density gradients making heterogeneous liquid layers and therefore disqualifying the Navier-Stokes equations for nanofilms. The crude sap motion takes the disjoining pressure gradient into account and the sap flow dramatically increases such that the watering of nanolayers may be analogous to a microscopic flow. Application to microtubes of xylem avoids the problem of cavitation and enables us to understand why the ascent of sap is possible for very high trees.Comment: 16 pages 1 figure New modern concept of the sap ascent in high trees taking into account the disjoining pressure in nanofilms of liquids. The motion of the sap is related to thin films slippering on the xylem wall

Continuum mechanics at nanoscale. A tool to study trees' watering and recovery

The cohesion-tension theory expounds the crude sap ascent thanks to the negative pressure generated by evaporation of water from leaves. Nevertheless, trees pose multiple challenges and seem to live in unphysical conditions: the negative pressure increases cavitation; it is possible to obtain a water equilibrium between connected parts where one is at a positive pressure and the other one is at negative pressure; no theory is able to satisfactorily account for the refilling of vessels after embolism events. A theoretical form of our paper in the Journal of Theoretical Biology is proposed together with new results: a continuum mechanics model of the disjoining pressure concept refers to the Derjaguin School of physical chemistry. A comparison between liquid behaviour both in tight-filled microtubes and in liquid thin-films is offered when the pressure is negative in liquid bulks and is positive in liquid thin-films and vapour bulks. In embolized xylem microtubes, when the air-vapour pocket pressure is greater than the air-vapour bulk pressure, a refilling flow occurs between the air-vapour domains to empty the air-vapour pockets although the liquid-bulk pressure remains negative. The model has a limit of validity taking the maximal size of trees into account. These results drop inkling that the disjoining pressure is an efficient tool to study biological liquids in contact with substrates at a nanoscale range.Comment: The paper is a review and overlap of my different papers about the watering of trees as a mathematical development of my paper in The Journal of Theoretical Biology. These results are presented together with new researches: transfer of liquid water and vapour between xylem microtubes, an explanation of ultrasounds generated in the watering network considered as sound pipes, numerical calculations of flows in thin liquid films and of Poiseuille flows in xylem microtubes, an estimation of the velocity for the ascent of crude sap and of the recovery time of trees during the spring perio

Physiological responses of six temperate tree species to water limitation

Abstract Direct evidence for the link between stem diameter variations (SDV) and the daily canopy water status, i.e. daily water potentials (Ψ), is rare, particularly for tall trees. It thus remains unclear up to what degree SDV readings are useful to estimate daily canopy Ψ. We measured SDV with point dendrometers at the stem base of tall, mature individuals of six European forest tree species in a near-natural temperate forest and compared them to daily canopy Ψ during the growing seasons of 2014 (wet) and 2015 (dry). SDV were de-trended for growth with two different approaches leading to the socalled tree water deficit (TWD). We found that midday Ψ can be predicted from TWD, independent of the growth-de-trending procedure to obtain TWD from SDV. Further, daily TWD was a better indicator for daily midday Ψ, particularly under dry conditions, than maximum daily shrinkage (MDS), another common quantity derived from SDV. Based on data from six temperate tree species, we conclude that TWD measured at the stem base is a consistent proxy for daily canopy midday Ψ of tall trees over the entire range of measured conditions. Keywords: drought, mature trees, maximum daily shrinkage, stem diameter variations, tree water deficit, water potentia

Smokejumper Magazine, January 2001

This issue of the National Smokejumper Association (NSA) Smokejumper Magazine contains the following articles: Dale Longanecker Sets Jump Record, First Jump in the Sequoias (Bob Nolan), Redding-Tall Trees (Bill Yensen), Personal notes from producer of smokejumper documentary (Steve Smith), Analysis of ADFF Final Report (Jim Veitch), Interview with Greg Greenhoe/Chair of ADFF study group, (Jim Veitch). Smokejumper Magazine continues Static Line, which was the original title of the NSA quarterly magazine.https://dc.ewu.edu/smokejumper_mag/1029/thumbnail.jp