Hydraulic failure and tree size linked with canopy die‐back in eucalypt forest during extreme drought

SummaryWe describe the operating principle of the detailed version of the soil-plant-atmosphere model SurEau that allows, among other things, to predict the risk of hydraulic failure under extreme drought. It is based on the formalization of key physiological processes of plant response to water stress. The hydraulic functioning of the plant is at the core of this model, which focuses on both water flows and water pools using variable hydraulic conductances. The model considers the elementary flow of water from the soil to the atmosphere through different plant organs (roots, trunk branches, leaves and buds) that are described by their symplasm and their apoplasm compartments. Within each organ the flow of water between the apoplasm and the symplasm is also represented; as well as the flow outside the system, from the symplasm of each organ to the atmosphere, through the cuticular conductance. For each organ, the symplasm is described by a pressure volume curves and the apoplasm by the vulnerability curve to cavitation of the xylem. The model can thus compute the loss of conductance caused by cavitation, a leading mechanisms of plant desiccation and drought-induced mortality. Some example simulations are shown to illustrate how the model works.

Download Full-text

Sudden forest canopy collapse corresponding with extreme drought and heat in a mediterranean-type eucalypt forest in southwestern Australia

European Journal of Forest Research ◽

10.1007/s10342-013-0690-5 ◽

2013 ◽

Vol 132 (3) ◽

pp. 497-510 ◽

Cited By ~ 121

Author(s):

George Matusick ◽

Katinka X. Ruthrof ◽

Niels C. Brouwers ◽

Bernard Dell ◽

Giles St. J. Hardy

Keyword(s):

Forest Canopy ◽

Extreme Drought ◽

Southwestern Australia ◽

Eucalypt Forest

Download Full-text

Drought-induced mortality: stem diameter variation reveals a point of no return in lavender species

10.1101/848879 ◽

2019 ◽

Author(s):

Lia Lamacque ◽

Guillaume Charrier ◽

Fernanda dos Santos Farnese ◽

Benjamin Lemaire ◽

Thierry Améglio ◽

...

Keyword(s):

Electrolyte Leakage ◽

Woody Species ◽

Stem Diameter ◽

Extreme Drought ◽

Hydraulic Failure ◽

Percentage Loss ◽

Point Of No Return ◽

Growing Conditions ◽

Two Parameters ◽

High Level

AbstractIn the context of climate changes, water availability is expected to severely decline. Consequently, there is a need to predict mortality of woody species, especially to find a physiological threshold to drought-induced mortality. Lavender species (Lavandula angustifolia and Lavandula x intermedia) which are important crops of the Mediterranean region are affected by a decline, notably caused by successive intense drought events. Lavender response to extreme drought events was monitored using continuous stem diameter measurements. Water potential, stomatal conductance, loss of xylem hydraulic conductivity and electrolyte leakage were also measured during desiccation, and recovery was evaluated after rewatering. Two parameters computed from stem diameter variations were related to stress intensity and resilience to stress: PLD (Percentage Loss of Diameter) and stem PLRC (Percentage Loss of Rehydration Capacity of the stem), respectively. We showed that plants did not recover when the PLD reached its maximal value (PLDmax) which was 21.27 ± 0.57% in both lavender species and whatever the growing conditions. This point of no return was associated with a high level of cell lysis evaluated by electrolyte leakage, and occurred far after the xylem hydraulic failure. We discussed the relevance of PLDmax as a threshold for drought-induced mortality and its physiological significance, in relation to the mortality mechanisms.One-sentence summaryUnder extreme drought, lavender death occurs when the water storage of the elastic compartment of the stem is exhausted.

Download Full-text

Faculty Opinions recommendation of Testing metabolic ecology theory for allometric scaling of tree size, growth and mortality in tropical forests.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1005071.373057 ◽

2006 ◽

Author(s):

Andrew Clarke

Keyword(s):

Tropical Forests ◽

Allometric Scaling ◽

Tree Size ◽

Metabolic Ecology ◽

Size Growth

Download Full-text

4Flowering Responses of Alpine Meadow Plant in the Qinghai-Tibetan Plateau to Extreme Drought Imposed in Different Periods

Chinese Journal of Appplied Environmental Biology ◽

10.3724/sp.j.1145.2013.00272 ◽

2013 ◽

Vol 19 (2) ◽

pp. 272-279 ◽

Cited By ~ 4

Author(s):

Chengxiang MOU ◽

Geng SUN ◽

Peng LUO ◽

Zhiyuan WANG ◽

Guangrong LUO

Keyword(s):

Tibetan Plateau ◽

Alpine Meadow ◽

Extreme Drought

Download Full-text

Spray Volume, Canopy Density, and Other Factors Involved in Thinner Efficacy

HortScience ◽

10.21273/hortsci.33.3.553d ◽

1998 ◽

Vol 33 (3) ◽

pp. 553d-553

Author(s):

C.R. Unrath

Keyword(s):

Tree Height ◽

Tree Canopy ◽

Tree Size ◽

Water Volume ◽

Canopy Density ◽

The North ◽

Run Off ◽

Tree Canopies ◽

Average Water ◽

Water Volumes

Historically, most airblast chemical applications to apple orchards used a single “average” water volume, resulting in variability of coverage with tree size and also the greatest variable in chemical thinning. This coverage variability can be eliminated by properly quantifying the tree canopy, as tree row volume (TRV), and relating that volume to airblast water rate for adequate coverge. Maximum typical tree height, cross-row limb spread, and between-row spacing are used to quantify the TRV. Further refinement is achieved by adjusting the water volume for tree canopy density. The North Carolina TRV model allows a density adjustment from 0.7 gal/1000 ft3 of TRV for young, very open tree canopies to 1.0 gal/1000 ft3 of TRV for large, thick tree canopies to deliver a full dilute application for maximum water application (to the point of run-off). Most dilute pesticide applications use 70% of full dilute to approach the point of drip (pesticide dilute) to not waste chemicals and reduce non-target environmental exposure. From the “chemical load” (i.e., lb/acre) calculated for the pesticide dilute application, the proper chemical load for lower (concentrate) water volumes can be accurately determined. Another significant source of variability is thinner application response is spray distribution to various areas of the tree. This variability is related to tree configuration, light, levels, fruit set, and natural thinning vs. the need for chemical thinning. Required water delivery patterns are a function of tree size, form, spacing, and density, as well as sprayer design (no. of nozzles and fan size). The TRV model, density adjustments, and nozzle patterns to effectively hit the target for uniform crop load will be addressed.

Download Full-text

A protocol for sampling vascular epiphyte richness and abundance

Journal of Tropical Ecology ◽

10.1017/s0266467408005786 ◽

2009 ◽

Vol 25 (2) ◽

pp. 107-121 ◽

Cited By ~ 24

Author(s):

Jan H. D. Wolf ◽

S. Robbert Gradstein ◽

Nalini M. Nadkarni

Keyword(s):

Tree Height ◽

Dry Weight ◽

Mantel Test ◽

Tree Size ◽

Tree Level ◽

Trunk Diameter ◽

Host Trees ◽

Epiphyte Communities ◽

Vascular Epiphyte

Abstract:The sampling of epiphytes is fraught with methodological difficulties. We present a protocol to sample and analyse vascular epiphyte richness and abundance in forests of different structure (SVERA). Epiphyte abundance is estimated as biomass by recording the number of plant components in a range of size cohorts. Epiphyte species biomass is estimated on 35 sample-trees, evenly distributed over six trunk diameter-size cohorts (10 trees with dbh > 30 cm). Tree height, dbh and number of forks (diameter > 5 cm) yield a dimensionless estimate of the size of the tree. Epiphyte dry weight and species richness between forests is compared with ANCOVA that controls for tree size. SChao1 is used as an estimate of the total number of species at the sites. The relative dependence of the distribution of the epiphyte communities on environmental and spatial variables may be assessed using multivariate analysis and Mantel test. In a case study, we compared epiphyte vegetation of six Mexican oak forests and one Colombian oak forest at similar elevation. We found a strongly significant positive correlation between tree size and epiphyte richness or biomass at all sites. In forests with a higher diversity of host trees, more trees must be sampled. Epiphyte biomass at the Colombian site was lower than in any of the Mexican sites; without correction for tree size no significant differences in terms of epiphyte biomass could be detected. The occurrence of spatial dependence, at both the landscape level and at the tree level, shows that the inclusion of spatial descriptors in SVERA is justified.

Download Full-text