Chlorophyll fluorescence in Exploratory Region Germany

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Dataset Abstract

Productivity is great in forests with a capacity to intercept incoming radiation and harness its energy efficiently. Thus, understanding the relationships between forest diversity, tree canopy biomass and photosynthetic parameters is central to predicting how diversity will affect a key ecosystem function (i.e., productivity). Specific hypotheses to be tested: I) higher tree species diversity enables greater exploitation of light within forest canopies due to niche partitioning, increasing photosynthesis and primary production (NPP); II) photosynthetic acclimation (ecological resilience to changing environmental factors) on singular species may vary according to the varying ecological conditions, but is supposed to be maintained at plot level in mixed population (interaction of different species-specific behaviors). Photosynthetic acclimation was measured with chlorophyll fluorescence (ChlF), by applying fast and reliable techniques based on the fast kinetics of the chlorophyll fluorescence induction in dark adapted leaves. This method is called JIP-test and is based on the measure of the variable fluorescence at different steps of the fluorescence induction. The measurements were carried out in 38 plots of Germany Exploratory Region.

Dataset Design

Chlorophyll fluorescence measurements were replicated on 8 randomly chosen leaves per tree per two level of crown (top and bottom). The measurements were done on the twigs after the dark adaptation (at minumum four hours in black plastic bag, at ambient temperature). In evergreen conifers chlorophyll fluorescence measurements took in current year needles (i.e., needles sprouted in 2012, 1-year needles)

Spatial Extent

Hainich forest, Germany

Taxonomic Extent

5 tree species (total number sampled tree/specie): Fagus sylvatica (90), Acer pseudoplatanus (52), Fraxinus excelsior (70), Picea abies (33), Quercus sp. (42)

Data Analysis

Data are treated at tree level (for each tree the data are treated for crown level)

Data columns available in the raw data part of this dataset

ID plot
Germany plot number. Unique number ascribed to each plot
Data group: Exploratory plot id
Values
GER02
GER04
GER01
GER03
GER05
Mixture level
Mixture level
Data group: Plot descriptor
Values
1
3
4
2
Species combination
Name of specie combined in each mixture. Code used: FS - Fagus sylvatica; AP - Acer pseudoplatanus; FE - Fraxinus excelsior; PA - Picea abies; Q - Quercus sp.
Data group: Tree species mix code
Values
AP-FE
AP-FS-FE-PA
AP-FS
AP-FE-Q
AP-FS-FE
Species
Scientific name of the trees sampled for leaf sampling (isotopic analysis, nitrogen analysis, fluorescence measurements, pathogen and insects)
Data group: Tree species
Values
Fagus sylvatica
Picea abies
Fraxinus excelsior
Acer pseudoplatanus
Quercus sp
ID tree
Number of sampled trees for leaf sampling (isotopic analysis, nitrogen analysis, fluorescence measurements, pathogen and insects)
Data group: Tree species id
Values
100
11
1
108
10
Top/Bottom
Two levels of crown sampled. Top (T) are the sunny leaves;bottom (B) is the lower part of the crown, in the shade
Data group: Tree id
Values
T
B
M0
Approximated initial slope (in ms-1) of the fluorescence transient normalized on the maximal variable fluorescence; Datagroup description: Approximated initial slope of the fluorescence transient
Unit: ms-1
Data group: Fluorescence parameters
Keywords: fluorescence, photosynthetic performance
Values
0.0894875
0.1045875
0.100325
0.10388571428571429
0.0949625
VJ
Variable fluorescence intensity at time 2 millisecond after the onset of the fluorescence induction by saturating light impulse (with intensity > 3000 µmol m-2s-1). It is expressed in arbitrary unit.; Datagroup description: Variable fluorescence at 2 millisecond
Unit: a.u.
Data group: Fluorescence parameters
Keywords: fluorescence, photosynthetic performance
Values
0.185825
0.17415000000000003
0.1710125
0.18759999999999996
0.1882
VI
Variable fluorescence intensity at time 30 millisecond after the onset of the fluorescence induction by saturating light impulse (with intensity > 3000 µmol m-2s-1). It is expressed in arbitrary unit.; Datagroup description: Variable fluorescence at 30 millisecond
Unit: a.u.
Data group: Fluorescence parameters
Keywords: fluorescence, photosynthetic performance
Values
0.5143125
0.49881250000000005
0.4834375
0.5306833333333334
0.5405333333333333
FV/FM
Maximum quantum yield of primary photochemistry in dark-adapted state. Expresses the probability that an absorbed photon will be trapped by the PSII reaction centre; Datagroup description: Maximum quantum yield of primary photochemistry in dark-adapted state
Unit: a.u.
Data group: Fluorescence parameters
Keywords: fluorescence, photosynthetic performance
Values
0.68165
0.6569
0.6349333333333333
0.6782285714285714
0.6538571428571429
Sm
Normalized area above the fluorescence induction curve. It is expressed in arbitrary unit and calculated as SM = Area/ (FM-F0), where F0 is the basl fluorescence intensity, measured at 20 microsecond after the onset of the fluorescence induction by saturating light impulse (with intensity > 3000 µmol m-2s-1).; Datagroup description: Normalized area above the fluorescence induction curve
Unit: a.u.
Data group: Fluorescence parameters
Keywords: fluorescence, photosynthetic performance
Values
14.812000000000001
136.9265875
14.810625000000002
124.4725375
14.3657125
PIabs
Performance index (potential) for energy conservation from photons absorbed by PSII to the reduction of intersystem electron acceptors; Datagroup description: Performance Index (potential) from photons absorbed
Unit: a.u.
Data group: Fluorescence parameters
Keywords: fluorescence, photosynthetic performance
Values
100.48594285714285
100.40202500000001
100.2527875
100.79706250000001
100.18075
PItot
PItot is the performance index for energy conservation from photons absorbed by PSII to the reduction flux of PSI end acceptors. This parameter is calculated from other parameters of the fluorescence induction curve analysis. It is expressed in arbitrary unit.; Datagroup description: Performance Index total
Unit: a.u.
Data group: Fluorescence parameters
Keywords: fluorescence, photosynthetic performance
Values
100.07233631225786
103.76189216340832
100.69953584953836
100.63342985863935
101.6842631826025