10.5061/DRYAD.JF2N3
Holmgren, Milena
Wageningen University & Research
Lin, Ching-Yen
Wageningen University & Research
Murillo, Julian E.
Wageningen University & Research
Nieuwenhuis, Annelies
Wageningen University & Research
Penninkhof, Joyce
Wageningen University & Research
Sanders, Natasja
Wageningen University & Research
Van Bart, Thomas
Wageningen University & Research
Van Veen, Huib
Wageningen University & Research
Vasander, Harri
University of Helsinki
Vollebregt, Marlies E.
Wageningen University & Research
Limpens, Juul
Wageningen University & Research
Data from: Positive shrub-tree interactions facilitate woody encroachment
in boreal peatlands
Dryad
dataset
2015
peatbog
Pinus sylvestris L.
ecosystem shift
decades
critical transition
positive interactions
2015-09-29T00:00:00Z
2015-09-29T00:00:00Z
en
https://doi.org/10.1111/1365-2745.12331
1361515 bytes
1
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Boreal ecosystems are warming roughly twice as fast as the global average,
resulting in woody expansion that could further speed up the climate
warming. Boreal peatbogs are waterlogged systems that store more than 30%
of the global soil carbon. Facilitative effects of shrubs and trees on the
establishment of new individuals could increase tree cover with profound
consequences for the structure and functioning of boreal peatbogs, carbon
sequestration and climate. We conducted two field experiments in boreal
peatbogs to assess the mechanisms that explain tree seedling recruitment
and to estimate the strength of positive feedbacks between shrubs and
trees. We planted seeds and seedlings of Pinus sylvestris in microsites
with contrasting water-tables and woody cover and manipulated both shrub
canopy and root competition. We monitored seedling emergence, growth and
survival for up to four growing seasons and assessed how seedling
responses related to abiotic and biotic conditions. We found that tree
recruitment is more successful in drier topographical microsites with
deeper water-tables. On these hummocks, shrubs have both positive and
negative effects on tree seedling establishment. Shrub cover improved tree
seedling condition, growth and survival during the warmest growing season.
In turn, higher tree basal area correlates positively with soil nutrient
availability, shrub biomass and abundance of tree juveniles. Synthesis.
Our results suggest that shrubs facilitate tree colonization of peatbogs
which further increases shrub growth. These facilitative effects seem to
be stronger under warmer conditions suggesting that a higher frequency of
warmer and dry summers may lead to stronger positive interactions between
shrubs and trees that could eventually facilitate a shift from moss to
tree-dominated systems.
Figure 1data_Exp 2Figure 1 data: Condition of experimental seedlings in
hummocks with contrasting shrub density and tree canopy in Experiment 2:
No Trees - Low Shrub biomass (NTLS), No Trees - High Shrub biomass (NTHS),
Present Trees - Low Shrub biomass (PTLS) and Present Trees - High shrub
biomass (PTHS) during the warmest growing season (2011) and at the end of
the experiment (2013). Seedling condition was defined as: healthy
(< 50% of the needles turned yellow or brown) or unhealthy
(> 50% of the needles turned yellow or brown). Seedlings were 1
month old at plantation time in the July 2010.Table 1_environmental
conditions_Exp 1Table 1 data: Environmental conditions and vegetation
characteristics in hummocks (circular and bands) and lawns for Experiment
1. Water table depth below surface is an average for the four growing
seasons (2010-2013)Table 2_ photosynthesis data_Exp 1Table 2
photosynthesis data: Photosynthesis rates for experimental pine seedlings
in hummocks (circular and bands) versus adjacent lawns for Experiment
1.Table 2_seedling responses_Exp 1Table 2 data: Responses of experimental
pine seedlings in hummocks (circular and bands) versus adjacent lawns for
Experiment 1 after 4 growing seasons. ST: Seeds inserted on top of moss;
SB: Seeds inserted below moss; Small seedling (1 month old at plantation
time); Large seedling (2 months old at plantation time). Emergence = % of
planted seeds emerged after 1 year. Condition = % healthy seedlings. Stem
growth corresponds to vertical stem growth for germinating (ST and SB)
seedlings and new stem growth for older (small and large) seedlings.Table
3_regression seedling-environment_Exp 1Table 3 data for generalized linear
models assessing the responses of experimental pine seedlings in hummocks
(circular and bands) and adjacent lawns for Experiment 1 during the whole
experimental period (2010-2013). ST: Seedlings from seeds inserted on top
of moss; SB: Seedlings from seeds inserted below moss; Small seedling (1
month old at plantation time); Large seedling (2 months old at plantation
time). Condition = % healthy seedlings. Growth = stem growth.Table
4_Environmental data_Exp 2Table 4: Environmental conditions in hummocks
with contrasting shrub density and tree canopy in Experiment 2: No Trees -
Low Shrub biomass (NTLS), No Trees - High Shrub biomass (NTHS), Present
Trees - Low Shrub biomass (PTLS) and Present Trees - High shrub biomass
(PTHS).Table 4 and Table S5a_seedling performance_Exp 2Table 4: Seedling
performance in hummocks with contrasting shrub density and tree canopy in
Experiment 2: No Trees - Low Shrub biomass (NTLS), No Trees - High Shrub
biomass (NTHS), Present Trees - Low Shrub biomass (PTLS) and Present Trees
- High shrub biomass (PTHS). Seedling emergence, condition and survival
from seeds inserted below the moss (SB), and from small planted
seedlings.Table S3_cox regression (survival analysis)_Exp 1Table S3: Data
for Cox survival analysis for experimental pine seedlings in hummocks
(circular and bands) versus adjacent lawns during 2010-2013. ST: Seedlings
from seeds inserted on top of moss; SB: Seedlings from seeds inserted
below moss; Small seedling (1 month old, 10 cm tall at plantation time);
Large seedling (2 months old, 30 cm tall at plantation time).Table S4_
regression seedling-environment 2011_Exp 1Table S4: Data for generalized
linear models assessing the responses of experimental pine seedlings in
hummocks (circular and bands) and adjacent lawns for Experiment 1 in 2011.
Small seedling (1 month old, 10 cm tall at plantation time); Large
seedling (2 months old, 30 cm tall at plantation time). Condition = %
healthy seedlings. Growth = stem growth.
Finland