examining the mechanistic pathways of interactions between shrubs and annual plants in semi-arid and...
TRANSCRIPT
EXAMINING THE MECHANISTIC PATHWAYS OF
INTERACTIONS BETWEEN SHRUBS AND ANNUAL
PLANTS IN SEMI-ARID AND ARID ECOSYSTEMS.
Alessandro Filazzola
PhD Candidate
Progress Report – March 6th
Positive plant-interactions
Multiple mechanisms
Filazzola & Lortie 2014
Multiple mechanisms
More than one dominant mechanism may operate at a time
Smit et al. 2009
No herbivores
With herbivores
Climate determines plant-interactions
Callaway et al. 2002
Dominant-mediated distribution
Survival of experimentally planted seedlings of Taraxacum
officinale within and outside Azorella monantha cushions at
3200 m a.s.l.
Cavieres et al. 2007
Purpose
To examine or decouple the different
mechanistic pathways and drivers of
plant-plant interactions in arid systems
Chpt Title Progress
1 A systematic review and conceptual framework for
the mechanistic pathways of nurse plants
Published in GEB, Summer 2014
2 Contrasting effects of drought-stress and consumer
pressure on plant-plant interactions in an arid
shrub-understory system
Submit to Ecology
3 The effect of a dominant shrub on annuals plants in
a desert system changes along a gradient of
continentality.
Active – repeat census in March 2015
4 Shrubs directly and indirectly increase seed
densities under canopy in arid environments
Data collection complete
5 Shrubs expand the species distributions of annual
plants in arid environments
Begin survey – April 2015
Chapter 3
Purpose: To determine how desert shrubs influence
annual plant productivity along a regional gradient of
climate.
H: The magnitude and frequency of positive
interactions between shrubs and annuals will be
greatest at intermediate levels of stress along a
regional gradient of continentality.
C3
C3
C3Ephedra californica
Shrub
Amsinckia tessellata
Annual
C3
x 20
0
100
200
300
400
10
12
14
16
18
20
22
0 1 2 3 4 5
Pre
cip
itati
on
(m
m)
Tem
pera
ture
(C
)
Gradient point
C3
Worldclim data: mean 1950-2000
0
100
200
300
400
14
15
16
17
18
19
0 1 2 3 4 5
Pre
cip
itati
on
(m
m)
Tem
pera
ture
(C
)
Gradient Point
ClimateWNA – 2007-2012
C3
0
5
10
15
20
25
0 1 2 3 4 5
Ari
dit
y I
nd
ex
Gradient Point
ClimateWNA – 2007-2012
Chapter 5
Purpose: To examine the role of shrubs in expanding
the range of annual plants.
H: Shrubs may be able to expand the realized niche
of an annual species beyond their distribution by
reducing the abiotic stresses that would otherwise limit
their establishment.
C5
Kelbaker road gradient
C5Elevation Elevation
Kelbaker road gradient
C5
C5Relative Humidity (%)
Temperature (C◦)
C5Relative Humidity (%)
Temperature (C◦)
C5
x 20x 20x 20x 20x 20
Relative Humidity (%)
Temperature (C◦)
?
?
C5
USDM - March 2015
C5
Future work
Chpt Title Goals
3 The effect of a dominant shrub on annuals
plants in a desert system changes along a
gradient of continentality.
Conclude census in March-April 2015
Data inputted June 2015
4 Shrubs directly and indirectly increase seed
densities under canopy in arid environments
Conduct statistical analysis & write-up
Fall 2015
5 Shrubs expand the species distributions of
annual plants in arid environments
Begin survey – April 2015
Field manipulations – Jan 2016
Thank you!