progress report march 19
TRANSCRIPT
DECOUPLING THE MECHANISTIC PATHWAYS OF
INTERACTIONS BETWEEN SHRUBS AND ANNUAL
PLANTS IN SEMI-ARID AND ARID ECOSYSTEMS.
Alessandro Filazzola
MSc Candidate
Progress Report – March 19th
Nurse-protégé Dominant-Subordinate
Sensu Grime 1998
Plant Interactions
Novelty
Novelty
More than one dominant mechanism may operate at a time
Smit et al. 2009
Novelty
Herbivore Protection
Abiotic stress reduction
Increased Herbivory
Abiotic stress reduction
Herbivore protection
Resource competition
Novelty
Positive plant interactions change with plant life-stage
0
5
10
15
20
25
1 2 3 4 5 6 7 8 9 10
Pla
nt
Tra
it
Distance from Dominant
Juvenile
0
5
10
15
20
25
1 2 3 4 5 6 7 8 9 10
Pla
nt
Tra
it
Distance from Dominant
Juvenile
Adult
Adapted from Miriti 2006
FarNear
Novel contributions to ecological theory
Decouple plant interactions by life-stage
Decouple mechanistic pathways
Biotic(5)
Seed Germinant Adult Flowering Reproduction
Abiotic(3,5)
Factors
Dominant
Subordinate
Seed Trapping*(4)
*
*
Chpt Title Progress
1 A systematic review and conceptual framework for
the mechanistic pathways of dominant plants
Re-submitted to GEB March 10
2 A meta-analysis of benefactor plant mechanisms
based on beneficiary life-stage.
Papers compiled – Data needs to be
extracted.
3 Ontogenetic shifts from positive to negative
interactions between desert plants change on an
environmental gradient.
January to April 2014
4 Shrubs directly and indirectly increase seed
densities under canopy in arid environments.
Preliminary census 2013 complete
5 Experimental manipulations of micro-
environmental conditions and herbivory of shrubs
in an arid system.
To be set up – April 2014
6 Experimentally testing the importance of the shrub
(E. californica) as a tool for restoration of semi-
arid grasslands
Need to meet with local land managers
Chapter 3
Purpose: To determine how desert shrubs mediate
annual plant productivity to changes in drought
stress and subordinate progression through plant life-
stages.
H: The sign of net interactions between shrubs and
annuals changes with annual plant life stage and
water availability.
Chapter 3
2013 Measure shrub characteristics
2014 Artificial water gradient
2014 Ambient water gradient
RII S
oil
Mois
ture
Chapter 4
Purpose: To determine if facilitation of annual seeds
by shrubs is a dominant pathway responsible for
annual plant distribution in desert environments.
H: Shrubs act to increase seedbank densities for
annual plants in desert systems either directly or
indirectly.
Chapter 4
Seed Adult Reproduction
1) Compare Microsites Shrub > Open
2) Compare controls C > S
3) Compare seeds removed A > O
4) Compare effect size of 2 & 3 2-e+ > 3-e+
1) Compare Microsites Shrub > Open
2) Compare controls C > S
**Both shrubs and annuals increase seed arrival**
0
100
200
300
400
500
600
700
800
900
1000
Plants & Seeds Seeds only
Nu
mb
er
of
Se
ed
s
Treatment
Shrub
Open
0
50
100
150
200
250
300
350
400
450
No seeds & artifical plant No seeds
Nu
mb
er
of
Se
ed
s
Treatment
Shrub
Open
3) Compare seeds removed A ≠ O
4) Compare effect size of 2 & 3 2-e+ > 3-e+
**Annuals increase seed arrival through increased reproduction**
Chapter 5
Purpose: To decouple shrub-mediated herbivory
effects on annuals from micro-environmental effects.
H: The relative difference in annual plants between
shrub and open microsites decreases with
reductions in consumer pressure and drought stress
Measure subordinate response
Biotic
Seed Germinant Adult Flowering Reproduction
AbioticFactors
Dominant
Subordinate
Chapter 5
Chapt Title Short term goals Long Term goals Dates
3 Ontogenetic shifts from
positive to negative
interactions between desert
plants change on an
environmental gradient.
Repeat census, collect biomass
and seeds, environmental data
Paper submitted for August
2014
Jan-April
census
2014
4 Shrubs directly and indirectly
increase seed densities under
canopy in arid environments.
Repeat census, add new seed
capturing devices and
measurements
Decouple the direct and
indirect mechanisms of seed
facilitation
Jan-April
census
2014-2016
5 Experimental manipulations
of micro-environmental
conditions and herbivory of
shrubs in an arid system.
Set up herbivory exclosures Water additions in 2015 and
measure annual success.
Jan-April
census
2015-2016
Upcoming field work
Thank you!