Estimation of Fuel Moisture Content (FMC), Equivalent water thickness (EWT), Dry Matter Content (DMC), and Specific Leaf Area (SLA) in eucalypt leaves.

doi:10.21203/rs.3.pex-2397/v1

Method Article

Estimation of Fuel Moisture Content (FMC), Equivalent water thickness (EWT), Dry Matter Content (DMC), and Specific Leaf Area (SLA) in eucalypt leaves.

https://doi.org/10.21203/rs.3.pex-2397/v1

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This protocol outlines the collection procedure of eucalypt leaves for analysis of various plant traits and the measurement of important water and physical traits. Fuel moisture content, dry matter content, equivalent water thickness, and specific leaf area provide insights into the flammability and biomass available for burning and the impact of moisture content on the fuel particles. Calculation of these parameters can all be achieved using the simple gravimetric methods. The key stages of this protocol include the collection of samples (1 day), the calculation of surface area and fresh weight (approximately 20 samples processed in two hours) and the measurement of dry weight (approximately 40 samples processed per hour).

Plant sciences

Environmental sciences

Eucalyptus

flammability

fire

drought

leaves

vegetation

leaf material

leaf traits.

Tree climbing equipment or Elevated Work Platform
Pole pruners
Large coolers (esky)
Scissors
Pruning scissors
Slingshot or throw-line launcher
Nylon line (3mm)
Line storage bag
Weight bags (different weights),
Precision balance (to four decimal places)
Plier hole punch
Photo scanner or camera
Large Ziploc plastic bags
Ice and/or Frozen water bottles and/or Blue ice blocks
Labels for bags
Plastic zip-lock bags
Permanent markers
Medical tape (for wrapping fingers)
Aluminium foil
Insect repellent
Sun cream (30+ SPF)
PPE (safety glasses, full body harness, gloves, hat)
Additional labels
Aluminium tins or cans to dry the samples

This protocol has been adapted from Spectranomics (2011), and Robles and De Santis (2005).

See also Wood et al. (2012), Youngentob et al. (2016) for details on branch collection method from tall trees.

1. Procedure to collect samples in the field

Before going to the field, ensure you’ve gone through section 2 (and other required) from Wood et al. (2012) - ‘Planning fieldwork’.
Important: Do not collect samples when they are wet from rain, dew, or fog as this could alter the FMC estimations. Only collect leaves 48 hours after the most recent rain event.
Before collecting the samples, label empty plastic zip-lock bags with the following headers (information will be added later):
Date [yyyy/mm/dd],
Time [hh:mm],
Species,
Plot No / Location,
Sample name or code,
Can also include other information such as specific weather events, issues with scale, etc.
Collect leaves from different heights of the tree (depending on the sampling strategy) using climbing, pole pruning, shooting techniques, or an elevated work platform (repeat for each tree, and for each species in the sampling strategy).
Several trees of the same species can be sampled using one plastic bag, depending on the sampling strategy.
Collect 10-20g of fresh leaves. Do not include twigs, stems, dead or diseased foliage, buds, cones, or berries in any stage of development.
Separate the leaves from the branch and store in the zip-lock bag. One zip-lock bag (10-20g) represents one sample. Collect as many samples as needed.
Store the labelled zip-lock bag with the sample in a cooler with ice (eski) to prevent dehydration of the leaves.

2. Laboratory procedure to measure FMC, EWT, and DMC.

Start the oven and set to 105⁰C (Matthews, 2010).
Avoid the use of paper bags to dry the leaves as they rapidly gain moisture after leaving the oven and can produce misleading results.
Select an aluminium can or tin and label it.
Place the scale on a flat surface, ensure it is levelled, and tare.
Weight the empty aluminium can and record the weight (e.g. field notebook, field/lab sheets, or lab notebook).
Tare the scale with the aluminium can on it.
Take the leaves out of a zip-lock bag (i.e. sample).
Scan the leaves, or take a photograph making sure there’s an appropriate scale within the field of view of the camera (e.g. ruler). Leaves should not touch or overlap.
Scan each sample at 600dpi (or higher resolution), saving each file as a black and white *.TIFF image (if possible) for leaf area estimation. Keep in mind that some samples may require more than one scan.
Clean scanner with a light duty tissue between each measurement to ensure there are no particles or smudges.
An alternative to scanning the leaves, is to use the “Easy Leaf Area” app for Android phones (https://github.com/heaslon/Easy-Leaf-Area) or other applications. Be aware that these phone applications have their own limitations.
Transfer the scanned leaves to the empty aluminium can. There should be as many aluminium cans as zip-log bags (i.e. samples).
Weight the aluminium can with the leaves inside and record the weight (e.g. field notebook, field/lab sheets, or lab notebook). This is the fresh weight.
Place all the cans (with leaves inside) in the oven, and leave for 24 hours at 105⁰C.
Record the date/time when samples went into the oven.
Do not put additional samples into the oven while drying one batch.
After 24h leaves should be dry and ready to be re-weighted.
Place an empty aluminium or plastic container on the scale (weighting boat), and tare
Take one can out of the oven and immediately transfer the sample weight it.
Weight each sample and fill Table 1. This is the dry weight.

Calculate FMC, EWT, DMC, and SLA

Use the following formula to calculate FMC:

FMC = (Fresh weight−Dry weight)/Dry weight × 100

Use the following formula to calculate EWT:

EWT = Fresh weight−Dry weight/Leaf Surface Area

Use the following formula to calculate DMC:

DMC = Dry weight/Leaf Surface Area

Use the following procedure to calculate SLA:
From each back and white image (i.e. scan), the leaf area is represented by the black portion of the image (i.e. the leaves) relative to the entire scan area. This returns the total leaf area.
This procedure can be done in a geographic information system (e.g. ArcMAP), ENVI, Image J, or in any programming language (e.g. python, R).
An alternative to scanning the leaves, is to use the “Easy Leaf Area” app for Android phones (https://github.com/heaslon/Easy-Leaf-Area).
Specific Leaf Area (SLA) and Leaf mass per area (LMA) are calculated as follows:

SLA = Total leaf area/Dry wight

LMA = Dry weight/Total leaf area

Fieldwork – 1 day

Collect sample from tree, place in labelled zip lock bag and keep in cooler box until wet weight is recorded, time taken for one sample is 2-3 minutes. The number of samples collected in a day is limited by the ability to store them adequately (in ice or -4°C) and process the samples the same day.

Processing surface area and wet weight

Scan or photograph leaves: 2-4 minutes per sample approximately.
Weigh tins and record the wet weight of individual samples: 10-20 samples per hour approximately.

Dry leaves – 24 hours

Record dry weight: 10-20 samples per hour approximately

The drying time of 24 hours is appropriate for the species measured in this experiment. If utilising the protocol on other species, it would be valuable to conduct a test on a handful of samples and record dry weight at 90-115°C every 24 hours until a consistent weight is obtained to ensure all moisture has been removed from leaves.

1. Spectranomics. Protocol for Leaf Spectroscopy. https://live-gao.ws.asu.edu/wp-content/uploads/2019/12/Spectranomics_protocol_Leaf_Spectroscopy-1.pdf (2011).

2. Robles, C. & De Santis, A. Protocolo de recogida de datos para el proyecto espectra. Version 2 (University of Alcalá, 2005).

3. Wood, S., Stephens, H., Foulkes, J., Ebsworth, E. & Bowman, D. AusPlots Forests Survey Protocols Manual. Version 1.6 (TERN - University of Tasmania, 2012).

4. Youngentob, K. N., Zdenek, C. & van Gorsel, E. A simple and effective method to collect leaves and seeds from tall trees. Methods in Ecology and Evolution 7, 1119-1123, doi:10.1111/2041-210x.12554 (2016).

5. Matthews, S. Effect of drying temperature on fuel moisture content measurements. International Journal of Wildland Fire 19, 800-802, doi:10.1071/WF08188 (2010).

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Estimation of Fuel Moisture Content (FMC), Equivalent water thickness (EWT), Dry Matter Content (DMC), and Specific Leaf Area (SLA) in eucalypt leaves.

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Estimation of Fuel Moisture Content (FMC), Equivalent water thickness (EWT), Dry Matter Content (DMC), and Specific Leaf Area (SLA) in eucalypt leaves.

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Version 1

Abstract

Figures

Equipment

Procedure

Time Taken

Anticipated Results

References

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Terms of Service

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