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Introduction: scope and purpose
How relationship
between plant and
pollinator is affected by
habitat fragmentation
Focus on a coastal
heath species –
Banksia robur
(Swamp Banksia)
Image source: (above) http://www.texas-wildlife.org/program-areas/category/property-rights
(below) http://www.anhs.com.au/images/
Previous research
Visits decline faster in:
tropical > temperate
vertebrates (birds,
bats) > invertebrates
Seed/fruit set decline
greater in self-
incompatible plants
Focus on herbs and
trees, forest and
grassland
Few coastal studies,
despite urbanisation
Image source: (above) Ricketts et al. 2008; (below) Montero-Castaño and Vila 2012
Coastal heathland
Sandy, low nutrient
soils
Habitat for
threatened species
Historically cleared
sand mining,
agriculture,
development
(~2 million ha)
endangered south
of Noosa
Eastern Ground Parrot
(Pezoporus wallicus)
Wallum Sedge Frog
(Litoria olongburensis)
Image sources: (parrot) http://www.environment.nsw.gov.au/threatenedspeciesapp/profile.aspx?id=10608#
(sedge frog) http://www.wildlife.org.au/projects/researchgrants/wallumsedgefrog.html
Research question
“Do pollinator behaviour and
reproductive success of B. robur differ
between intact and fragmented coastal
heath?”
Plant-pollinator interactions
Banksia robur
Fragmented vs. intact habitat
Methods: site selection Two coastal heath
sites (intact and
fragmented)
Five replicate plots
(20 × 5 m) per site
At least three
flowering plants per
plotWest of Dilli Village,
Fraser Island (Intact)
East Weyba Section,
Noosa N.P. (Fragmented)
Observations
40 × 20 min
observations
morning and
afternoon
twice per plot
Bird species –
foraging behaviour
duration
movement
between B. robur
flower spikes
number of visits
Images: background – visiting P. nigra; inset – observers. Courtesy of Marvin Scheiffer
Sampling 216 samples
up to 25 fruits per plot
Seed set
calculated as = follicles
per fruit (one seed per
follicle)
(a) (b)
(c)
(a) B. robur fruit with closed follicles; (b)
with open follicles; and (c), left – winged
seed, centre – separator, and right –
seedless wing.
Species Intact Fragmented Total
(a) White-cheeked Honeyeater (Phylidonyris nigra) 349 26 375
(b) Lewin’s Honeyeater (Meliphaga lewinii) 0 6 6
(c) Noisy Friarbird (Philemon corniculatus) 0 2 2
(d) Red-browed Finch (Neochmia temporalis) 1 0 1
Total 350 34 384
(a) (b) (c) (d)
Results: bird species observed
Image credits (a,b,d): David & Diane Armbrust, http://www.anhs.com.au/images/ (c): David Cook,
http://www.flickr.com/photos/kookr/2877951061/
Visitation rate
0
2
4
6
8
10
12
14
16
18
20
Intact Fragmented
Me
an
nu
mb
er
vis
its
/ 20m
in
Site
Frequency of bird
visits to flower spikes
was significantly
lower in fragmented
coastal heath
Mann-Whitney U Test (U(39) =
106, Z = -2.923, p = 0.010).
10 × more visits in
intact habitat
Duration of visits
Mean duration of
bird visits was similar
between sites
Mann-Whitney U Test (U(383) =
6 174.5, Z = 0.363, p = 0.716).
0
10
20
30
40
50
60
Intact Fragmented
Me
an
du
ratio
n o
f v
isit (
sec
)Site
Movement between flowers
Visitor travel
between flower
spikes was similar
across sites
Independent Samples T-Test
(t(9.5) = 2.247, p = .050).
0
5
10
15
20
25
30
35
40
45
Intact Fragmented
Me
an
pe
rce
nt
vis
its
with
in
ter-
flo
we
r
tra
ve
l (%
)
Average seed set
Seed set was
significantly reduced
in fruits from
fragmented sites
Independent Samples T-Test
(t(213) = 3.249, p = 0.001).
0
10
20
30
40
50
60
70
Intact FragmentedM
ea
n s
ee
d s
et
pe
r fr
uit
Site
Discussion: reduced visits
Less visits in fragmented
population,
e.g. B. goodii, B. cuneata
perceived decline in
nesting or foraging
resources
competition with
aggressive edge species
Forage in nearby
woodland
P. nigra dual habitat
Image source: (above) http://upload.wikimedia.org/wikipedia/commons/1/13/Noisy-Miner-juvenile.jpg
(below) http://farm7.static.flickr.com/6068/6158449973_74676438f7.jpg
Lower fertility
22% reduction in
average seed set
changes in
pollinator activity
disruption to
pollination
services
limited seed
production
Lower fertility
Similar to that found in
other fragmented
ecosystems:
tropical forest 20%
grassland 16%
Risk to demographic
turnover:
Low seed set low %
survival seedlings
E.g. up to 80%
seedling mortality
from kwongan
fragments
Alternative explanations
Smaller plant population size and
low density in fragmented site
‘inbreeding’ poor pollen
quality fewer seeds
E.g. B. sphaerocarpa
Physiological stress on plants (e.g.
drier conditions)
less resources, less output
Conclusion
Pollen limitation due to
habitat fragmentation
reduced bird visits lower
seed set of B. robur in
fragmented heathland
Potential risk to long-term
viability of population
Larger studies needed to
assess risk