7.13.1 Introduction
Foliar analyses are an effective means of recognizing pollutant-related stress in forest trees. Foliar analyses provide the means for assessing changes in the content of nutrients and contaminants in needles and leaves. Analyses of both live material (foliage chemistry) and dead material (shed foliage = litter chemistry) are important for assessing nutrient fluxes and nutritional status of forest trees.
Elements to be determined: Ca, K, Mg, Na, N, P, S, Cu, Fe, Mn, Zn and TOC
Optional: Al, As, B,Cd, Cl, Cr, F, Mo, Ni and Pb
7.13.2. Field methods
Undertake litterfall sampling systematically or randomly, not just under the dominant tree species. Litterfall collectors should be placed in connection with throughfall collectors, with the purpose of assessing litterfall for the catchment as a whole. Connection with permanent soil plots is less important. Six to 12 collecting sacks are used.
Litterfall is collected with litter sacks. Litter sacks should be made of inert material and be 0.5 m deep to prevent litter from blowing away. Attach the sack to a wooden frame of known area (0.25 - 0.5 m2). The frame should be horizontal and applied to poles, one in every corner, driven into the ground. The sack should not touch the ground as moisture entering the sack will accelerate the decomposition process.
All shed brown needles/leaves should be sorted out from the rest of the fine litter and analysed for chemistry. Comparisons with foliage concentrations provide information about translocation and nutrient status.
Sampling should be undertaken at least monthly, but samples can be pooled to periodic samples. Transfer the litter to large paper/plastic bags using gloves and transport them to the laboratory.
Make pooled samples of litterfall for chemical analysis. Avoid all contamination from smoke or laboratory tables. Handle the samples on clean laboratory paper, glass shields or clean polyethene.
Dry the samples at 40ºC to a constant weight. Alternatively, samples can be cooled lower than 5ºC until drying can be performed.
7.13.3 Chemical analyses
For chemical analyses see chapter FC Foliage chemistry.
7.13.4 Data reporting
Values are reported on oven dry basis (105ºC). Parameters and units are the same as in Foliage chemistry.
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Mandatory parameters
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list
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unit
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LDEP
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IM
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litterfall amount (oven dry weight)
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g/m2
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STOT
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DB
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total sulphur
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mg/g
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NTOT
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DB
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total nitrogen
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mg/g
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PTOT
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DB
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total phosphorus
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mg/g
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CA
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DB
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calcium
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mg/g
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MG
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DB
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magnesium
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mg/g
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K
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DB
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potassium
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mg/g
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NA
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DB
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sodium
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µg/g
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MN
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DB
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manganese
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µg/g
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FE
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DB
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iron
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µg/g
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CU
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DB
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copper
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µg/g
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ZN
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DB
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zinc
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µg/g
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TOC
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DB
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total organic carbon
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mg/g
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Optional parameters:
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list
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AL
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DB
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aluminium
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µg/g
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AS
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DB
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arsenic
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µg/g
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B
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DB
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boron
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µg/g
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CD
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DB
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cadmium
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µg/g
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CL
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DB
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chloride
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µg/g
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CR
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DB
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chromium
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µg/g
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F
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DB
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fluoride
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µg/g
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MO
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DB
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molybdenum
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µg/g
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NI
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DB
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nickel
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µg/g
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PB
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DB
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lead
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µg/g
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Example files
LF example Excel file
LF example ASCII file
- File identifier SUBPROG states the subprogramme.
- MEDIUM refers to the dominant tree species of the stand where litterfall is collected (NCC code list B4, see Annex 6 and TF chapter for a list of common tree species).
- LEVEL is given as sampling height from the ground (cm), optional here.
- Spatial pool SPOOL refers to the number of individual samples taken for pooled analysis.
- Litterfall amount is given as a sum for the period, status flag is S. General information on flags is given in Chapter 4.
- Sampling year and month are given as YYYYMM, in the example as 201100 when the pooled sampling is assumed to have covered a period of several months. Day field is left blank.