Tree and shrub species functional traits across a light-availability gradient in Dujiangyan

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Dataset Abstract

Here we present the result from a two-year field experiment in which we transplanted seedlings of 14 woody species representing three contrasting functional types(broad-leaved evergreen, deciduous and coniferous species) along a light gradient into the understory of a subtropical forest in southwestern China. We assessed mortality and measured the growth rate of all transplanted individuals at intervals. To further understand the mechanisms leading to seedling mortality and growth, we examined three functional traits of transplanted individuals (SLA, leaf mass ratio, wood density).

Dataset Design

Fifteen shade houses were arranged in a 3 × 5 grid with a 2 m distance between shade houses. These shade houses represented three light levels with five houses as replicates for each level. The light levels were created by covering shade houses with layers of neutral shade netting with different density. The shade houses had a height of 2.2 m and an area of 4 × 5 m. Instantaneous PAR (Photosynthetically Active Radiation) readings were made both outside and inside each shade house using an SKP 215 PAR Quantum sensor. These measurements indicated that the plants were receiving 43.7±2.1%, 17.1±0.73%, 2.74±0.1% of full daylight in the high-, medium-, and low-light shade houses. The light condition gives a good simulation to the natural light gradient in the forest as 50% is usually encountered in open areas and 3% in understory of subtropical forests in the region (observations by the author). To avoid environmental heterogeneity affecting experiment results, we applied a random-block design, i.e. each of the three light levels occurred once in each block of three houses and was positioned in a random sequence. The fourth light level (full daylight) was performed outside of the shade houses. We marked 5 quadrates next to each other besides the area of the shade houses, with at least a distance of 1 m between quadrates.Air temperature and soil temperatures were measured with a Hobo U12-015 temperature data logger. We hung one thermometer in the air inside one of the shade houses and buried another thermometer 10 cm below the top soil in the same shade house. Measurements were taken every hour from day 58 until the end of the experiment, and mean daily temperatures were calculated. Seeds were collected from under parent trees in subtropical forests in the Dujiangyan region in spring 2007. All seeds were processed on the day of collection.Seeds were then germinated under a shade cloth in a nursery. In August 2007, the seedlings were individually transplanted into plastic plots (30 cm height, 30 cm diameter) filled with farmland top soil. Two seedlings from each of the 14 species were placed into each shade house and in each full-light quadrate, yielding a total of 560 pots with a single test plant each. The pots were arranged in a hexagonal pattern with a distance of 0.5 m between neighboring pots (0.8 m between the centers of neighboring pots) to avoid shading. Two weeks after moving pots to shade houses, we replaced dead seedlings with ones of the same species sown at the same time. Plants were watered every 3–4 days or when the soil was dry.The traits included the three growth components net assimilation

rate (NAR), specific leaf area (SLA) and leaf mass ratio (LMR) as well as other

gas-exchange traits

Spatial Extent

The experiment was carried out from August 2007 to July 2009 in an experimental garden near Dujiangyan, southwest China (31°04’ N, 103°43’ E). The climate in the region is characterized by a mean annual temperature of 15.2°C and an average July temperature of 25°C. The mean annual precipitation at Dujiangyan is 1341 mm with a dry season in winter (November–April) and with warm and rainy summers (May–October). The annual average relative humidity is above 80%. The vegetation in the region can be classified as a secondary conifer and broad-leaved mixed subtropical forest.

Temporal Extent

August 2007 to July 2009

Taxonomic Extent

The 14 species used in this study are all woody species commonly found in the study region. These species were selected according to their leaf habit, successional status and seedling availability. There were seven broadleaved-evergreen and seven broadleaved-deciduous species. The deciduous species are either early-successional (Alangium chinense, Castanea henryi and Rhus punjabensis) or intermediate. In evergreen species, Pyracantha fortuneana and Lindera communis are early-successional, Phoebe zhennan is late-successional and the rest are intermediate.

Data columns available in the raw data part of this dataset

species
species short name; this is a number which refers to the species given in the column "spcode"
Data group: Helper
Values
1
11
10
13
12
spcode
Scientific name of the respective species; according to the "Flora of China"
Data group: Scientific plant species name
Keywords: species
Values
Aralia chinensis
Camellia oleifera
Alangium chinense
Choerospondias axillaris
Castanea henryi
ed
e-evergreen; d-decidous; Datagroup description: Plant functional group or life form
Data group: Plant functional group or life form
Keywords: functional trait
Values
e
d
edcon
ey-evergreen conifer; e-evergreen broad-leaved; d-deciduous broad-leaved; Datagroup description: Plant functional group or life form
Data group: Plant functional group or life form
Keywords: functional trait
Values
d
ey
e
block
block; Datagroup description: Block
Data group: Dujiangyan experimental blocks
Keywords: location
Values
1
2
4
3
5
house
house; Datagroup description: Block
Data group: Dujiangyan experimental blocks: houses
Keywords: location
Values
10
12
11
13
1
indiv
individuals; Datagroup description: Individual Identifier
Data group: Dujiangyan Individual Identifier
Keywords: tree, object, seedling
Values
2
1
4
3
ID
identical number for each seedling; Datagroup description: Individual Identifier
Data group: Dujiangyan Individual Identifier
Keywords: tree, object, seedling
Values
10011
10012
10013
10014
10021
date
number of days after initiation of the experiment
Unit: day
Data group: Date time information
Keywords: date
Values
677
203
351
harvest
times of the harvests
Data group: Time series
Keywords: date
Values
2
3
1
height
seedling height
Unit: cm
Data group: Plant height
Keywords: response variable, height, size
Values
100.3
100.5
100.6
10
100.7
change
change of light level (c-changed,uc- unchanged)
Data group: Helper
Keywords: design variable
Values
c
uc
girth_1
girth in one direction;
Unit: mm
Data group: Stem girth
Keywords: response variable, growth
Values
0.12
0.09
0.1
0.08
0.11
girth_2
girth in one direction;
Unit: mm
Data group: Stem girth
Keywords: response variable, growth
Values
0.1
0.12
0.09
0.14
0.13
light
light level (L-low, M-medium, H-high, O-open air); Datagroup description: Soil attributes
Data group: Solar radiation
Keywords: design variable
Values
H
O
M
L
light.perc
percentage of light; Datagroup description: Soil attributes
Unit: %
Data group: Solar radiation
Keywords: design variable
Values
3
100
17
44
light_a
light level after changing; Datagroup description: Soil attributes
Data group: Solar radiation
Keywords: design variable
Values
O
L
M
H
light_a.perc
percentage of light after changing
Unit: %
Data group: Solar radiation
Keywords: design variable
Values
100
17
3
44
Carbon
carbon concentration in the leaves
Unit: %
Data group: Carbon
Keywords: functional trait
Values
41.49
37.28
38.35
31.66
32.44
Hydrogen
hydrogen concentration in the leaves
Unit: %
Data group: Chemical elements
Keywords: functional trait
Values
4.982
4.355
4.421
4.723
5.167
Nitrogen
nitrogen concentration in the leaves
Unit: %
Data group: Nitrogen
Keywords: functional trait
Values
1.132
1.286
1.141
1.125
1.122
Amax
maximum assimilation rate on area basis
Unit: umol CO2 m-2 s-1
Data group: Photosynthesis
Keywords: functional trait
Values
10.56666667
10.46666667
10.31666667
10.14666667
0.284966667
BiomassR
root biomass
Unit: g
Data group: Above and below ground biomass measurement
Keywords: root, belowground biomass
Values
0.05
0.06
0.04
0.07
0.03
BiomassS
stem biomass
Unit: g
Data group: Above and below ground biomass measurement
Keywords: stem, aboveground biomass
Values
0.02
0.03
0.07
0.05
0.06
BiomassL
leaf biomass
Unit: g
Data group: Above and below ground biomass measurement
Keywords: leaf, aboveground biomass
Values
0.05
0.01
0.08
0.03
0.06
BiomassA
total biomass
Unit: g
Data group: Above and below ground biomass measurement
Keywords: aboveground biomass
Values
0.2
0.23
0.17
0.21
0.16
thickness
leaf thickness
Unit: mm
Data group: Leaf thickness
Keywords: functional trait
Values
17
14
15
16
13
Larea
leaf area
Unit: cm2
Data group: Leaf area
Values
10045.24899
1006.69
10047.51172
0.63
0.859570313
sla
Specific leaf area
Unit: cm2 g-1
Data group: Specific leaf area
Values
0.0865030674837419
0.163777777777778
0.139721254406915
0.127343750074074
0.1178
Amass
maximum assimilation rate on mass basis
Unit: nmol g-1 s-1
Data group: Photosynthesis
Values
0.597835
1006.84967441295
1084.42871920066
1107.98481186985
0.365264323086688
Lcp
light compensation point
Unit: %
Data group: Light compensation point
Values
10.8492638500757
10.7602387794836
11.3981477401514
106.158549444772
100.809266385376