Main Experiment: Removal experiment – predictor variables

Usage Rights

This data is Free within projects.

BEF-China: SP11 internal

Dataset Abstract

SP 11 studied the interaction between tree layer diversity and herb layer diversity in highly diverse subtropical forests. Apart from species richness alone, a high functional diversity of resident communities influences ecosystem functioning. Effects of functional group losses in herb layer communities of the Main Experiment were studied by species removal. Removing species or functional groups allows studying within-community (biomass) compensation and effects on the tree individuals. We applied a functional group removal experiment in the Main experiment in which most dominant functional groups (herbs, grasses, ferns and woody weeds) were experimentally removed by selective weeding. By comparing the removal subplots with control plots containing the entire suite of species, we assess the role of functional groups for herb layer feedback effects on young trees and for evaluating community responses to such a loss at the same time.

Dataset Design

The removal experiment was established on Site A and B in June 2011 and was conducted within each 32 plots on Site A and on Site B, thus representing the full tree diversity gradient of the Main Experiment, including the tree diversity levels one (n = 16), two (n = 8), four (n = 4) eight (n = 2), 16 (n =1) and 24 (n = 1) at both sites. Within the northern four rows of each plot, five subplots (5 m × 5 m) containing each 16 trees, were established in June 2011 and randomly assigned to one of five removal treatments. Thus, the removal experiment was based on a total of 320 (2 × 32 × 5) subplots. Five levels of removal treatments were applied, i.e. woody species (W), fern species (F), grass species (G) and herbaceous species (H) were removed. One additional subplot served as a control without removal. The initial removal weeding was carried out in June 2011, where the aboveground biomass of each function group was entirely removed by selective cutting. Additional weeding took place in 2012, in June and September each, and in June 2013. The dry weight of the removed aboveground biomass was determined subsequent to the weeding campaigns. In August 2012, a vegetation monitoring was conducted for all 320 subplots. In September 2012, a subsample of each subplot was harvested for productivity assessment. In VIPs of 1- and 2-species mixtures, the total aboveground biomass was harvested within each of the removal subplots as a pooled sample of three 0.5 m × 0.5 m replicates and separated by functional group: fern, grass, woody species and herbs. In VIPs of 4-, 8- 16- and 24-species mixtures, five replicates were harvested and pooled by subplot. In September 2012 the relative light conditions and the soil moisture were measured in eaxh subplot.

Spatial Extent

Main experiment, Site A, Site B, no shrub VIPs

Temporal Extent

Initial weeding of removal treatments was performed in June 2011

Data Analysis

For each subplot, relative light conditions, soil moisture, altitude, slope and aspect is given; for details see data group description.

Data columns available in the raw data part of this dataset

PTAG
Research plots on the main experiment have a "p" in front of their IDs and then a 6 digit code: Plots in the main sites A and B are named according to their position in the original spreadsheet, in which they were designed. They consist of 6 digits: _1st digit_: Site (1:A, 2:B), _digit 2and3_: southwards row: as in spreadsheets the rows are named from the top to the bottom; _digit 4 and 5_: westward column: as in the original spreadsheet, but the letters are converted to numbers (A=01, B=02); _6th digit_: indicator, if the plot has been shifted a quarter mu. Example: "p205260": "p" means that this is a plot that is specified. "2" means, that we are at site B. Now the coordinates of the south - west corner: "0526". Since "e" is the fifth letter of the alphabet, this is Plot E26. The last digit "0" means that this plot was not moved by a quarter of a Mu, as some sites in Site A. The 6th digit can also indicate the subplot within the plot. "5", "6", "7", "8" indicate the northwest, northeast, southeast, and southwest quarter plot respectively.
Data group: BEF research plot name
Keywords: plot, Main Experiment
Values
p103320
p106210
p105310
p105340
p105330
Plot
Plotnumber; Datagroup description: Plotnumber on Site A and B; 32 VIP plots with no shrub treatment;
Data group: Helper
Keywords: VIP plots, plot
Values
E33
C32
E34
D29
E31
treatment
removal treatment: c= control, without removal; W= removal of woody species; F = removal of fern species; H= removal of herbaceous species; G= removal of grass species; Datagroup description: removal treatment: c= control, without removal; W= removal of woody species; F = removal of fern species; H= removal of herbaceous species; G= removal of grass species
Data group: Treatment
Keywords: experimental treatment, removal experiment
Values
w
f
h
c
g
tree_diversity
tree diversity of each plot
Data group: Taxonomic biodiversity
Keywords: diversity treatment, species diversity
Values
24
4
1
2
16
Site
Site on Main experiment; Datagroup description: Site A or B
Data group: Helper
Keywords: Site A, Site B
Values
B
A
light
light conditions; Datagroup description: relative light conditions for each subplot in 2012-09 at 1.2 m height, mean value for each subplot; three measuring points for subplots with tree diversity level one and two; five measuring points for subplots with tree diversity level 4-24
Unit: percent
Data group: Solar radiation
Keywords: solar radiation
Values
0.039877482
0.039985908
0.03119257
0.038301593
0
soil_moisture
soil moisture of each subplot in 2012-09, mean value for each subplot; three measuring points for subplots with tree diversity level one and two; five measuring points for subplots with tree diversity level 4-24; Instrumentation: Thetaprobe ML2x
Unit: VolumePercent
Data group: Soil moisture
Keywords: soil moisture
Values
19.26666667
18
18.98
20.2
17.34
ALTITUDE
ALTITUDE
Data group: Elevation
Keywords: elevation
Values
116.583125
116.363125
108.9375
116.099375
112.299375
ASPECT
ASPECT
Data group: Aspect
Keywords: aspect
Values
103.37375
104.500625
101.295
106.299375
103.783125
SLOPE
SLOPE
Data group: Inclination
Keywords: inclination
Values
12.04375
11.529375
11.40375
10.293125
12.530625