Main Experiment: Seedling addition experiment - growth and biomass data

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This data is Private.

Dataset Abstract

While coexistence in plant communities is frequently explained by effects of resource niche partitioning, the Janzen-Connell (J-C) hypothesis is an alternative approach that has been assumed as a major ecological mechanism explaining high species richness levels, in particular, in tropical forest ecosystems. Central components of the J-C hypothesis are non-competitive effects of density- and distance-dependence, thereby two drivers that contribute independently to species coexistence, but that are ultimately linked in the field. Here, we make use of the forest Biodiversity-Ecosystem Functioning project in subtropical China (BEF-China) to estimate density and distance dependence effects by means of a reciprocal tree seedling transplant experiment. Using monocultures of ten and seven tree species, respectively planted at two different sites, juveniles of all species were grown in their own (home) and in all other monocultures (away), thereby testing for distance effect, just as in three different levels of planting density, testing for density effects.

In addition, we repeated a similar set-up in a nearby common garden experiment, where we added a 'shadow' treatment to simulate different light conditions induced by the canopy layer. The general aim of the common garden experiment is to test for additional density dependent intraspecific competition for light in the absence of host-specific agents necessary for J-C effects. Density dependent patterns that are prevalent in the main experiment, while not being prevalent in the common garden experiment can be considered true J-C effects (see "Common Garden Experiment: Seedling addition experiment - growth and biomass data" for further details)

Dataset Design

We implemented a reciprocal transplant experiment with juvenile plants using monocultures of 11 different tree species and following a home-away design, i.e. planting transplants in their own monoculture (home) and in a different one (away). The species represent a subset of the Main Experiment’s species pool and had been selected according to their representation at the two sites and finally included 6 evergreen and 5 deciduous species. From the species pool, 10 species were implemented at site A and 7 species at site B, thus 6 species were used on both sites. For each species, 3 monoculture plots were selected at each site and used for subplot implementation according to the project-specific experimental setup. The general design of BEF-China provides two ‘true’ replicates of each species’ monocultures at the plot level (i.e. where all 20 * 20 planted individuals belong to the same species). As a third replicate, we used 2-species mixtures including the respective target species and therein, all subplots were established in between four individuals of the target species.

All site-specific target species were planted in suplots either established in their own monoculture (home: 3 replicates each) or in monocultures of the other species within site (away: 9 species * 3 replicates, i.e. 27 plots site A and 18 for site B, respectively). Three monocultures in total, (1 in site A and 2 in site B) could not be realised. This approach was used to test for distance dependence.

In order to test for effects of density-dependence, each subplot, was then subdivided in split-plots where tree seedlings were planted in conspecific communities at different density levels of 4, 9 and 25 individuals each. Accordingly, in target plots at site A, each five subplots (hosting each two species) were implemented, whereas at site B, the number of subplots per plot was lower because of the lower number of species tested. Thus, in each 29 and 19 plots (for site A and B, respectively), 5 and 4 subplots (for site A and B, respectively) were randomly allocated with each subplot 1.5 m x 1.0 m in size. Each splitplots occupied an area of 0.5 x 0.5 m in size. Species × density combinations were randomly allocated within subplot.

Spatial Extent

Plots of the main experiment on Site A and B

Data columns available in the raw data part of this dataset

Samplenr
An individual number for each taken sample
Data group: Helper
Values
B38.1.1.1.4.A
B38.1.1.1.3.A
B38.1.1.1.2.A
B38.1.1.1.0.A
B38.1.1.1.1.A
Seedlingnr
An individual number for each seedling
Data group: Helper
Values
B38.1.1.3
B38.1.1.5
B38.1.1.4
B38.1.1.2
B38.1.1.1
Plot
Plot
Data group: Helper
Values
C37
B38/C38
F21
E24
E33
Subplot
An individual number for each subplot
Data group: Helper
Values
1
3
2
4
5
Splitplot
An individual number for each splitplot
Data group: Helper
Values
5
1
4
2
3
Indnr_Splitplot
An individual number for each seedling within each splitplot
Data group: Helper
Values
13
10
1
12
11
Record
number for the records
Data group: Helper
Values
1
0
3
2
4
Site
Site
Data group: Experimental Site
Values
B
A
PTAG
PTAG
Data group: BEF research plot name
Values
p105240
p106210
p102381
p105330
p103370
Date
Month and year of record
Data group: Date time information
Values
June_2015
August_2015
July_2015
May_2015
March_2016
Planted_Species
Species planted. The scientific species fullnames are based on the "Flora of China". Scientific species names consist of epithet and genus.
Data group: Scientific plant species name
Values
C.camphora
C.glauca
C.fargesii
C.sclerophylla
D.glaucifolia
Density
Density of planted species within each splitplot
Data group: Seedling Density
Values
9
4
25
Distance
indicator for species either planted in their own monoculture (home) or in a different one (away)
Data group: Distance
Values
Home
Away
Home_Species
Species of the monoculture. The scientific species fullnames are based on the "Flora of China". Scientific species names consist of epithet and genus.
Data group: Scientific plant species name
Values
C.sclerophylla
D.glaucifolia
L.formosana
C.glauca
C.camphora
Dead
indicator for species dead (1) or alive (0)
Data group: Living status
Values
1
0
Height_P
Height of the seedling up to the last photosynthetically active tissue
Unit: cm
Data group: Plant height
Values
10
0
100
102
101
Height_G
Height of the seedling up to the last still living tissue
Unit: cm
Data group: Plant height
Values
0.6
0.8
0.9
0.5
0.4
Leaves_Liv
Number of living leaves
Data group: Plant leaf number
Values
0
102
1
100
10
Leaves_Dam
Number of damaged leaves
Data group: Plant leaf number
Values
1
102
100
10
0
Leaves_Dead
Number of dead leaves on seedling
Data group: Plant leaf number
Values
10
1
12
0
11
Damage_pro
estimated leave damage in percent
Unit: in percent
Data group: Herbivore damage
Values
0.2
0.3
0.1
0
0.5
Biomass_Above
aboveground dry matter biomass in Sep. 2016
Unit: g
Data group: Above and below ground biomass measurement
Values
0.02
0.01
0.04
0.03
0.05
Biomass_Below
belowground dry matter biomass in Sep. 2016
Data group: Above and below ground biomass measurement
Values
0.01
0.05
0.02
0.03
0.04
LAI
Leaf area index measured above the planted seedlings (1m height) in each subplot
Data group: Leaf Area Index (LAI)
Values
0.002361707
0.008523142
0.008545297
0.011953125
0.001953125
Slope
inclination of each subplot
Data group: Inclination
Values
12
1
13
0
10
Northness
Northness of the subplot
Data group: Aspect
Values
-0.0751360908983532
-0.0220966192786839
-0.0574724308476655
-0.0397907599311577
0.0663068583517113
Comments
if problems occurred, e.g. after the survival measurement (record = 0) nearly all dead seedlings have been replaced. Those not replaced have been marked
Data group: Comments
Values
Dead_in_October_2015;not_replanted
Animale_passed;not_replanted
Animale_passed
landslide
Dead_in_October_2015