Final presentation for my Special Research Project over the summer of 2013-14. This project investigated habitat fragmentation effects on pollination and reproductive success by comparing plant-pollinator interactions between Banksia robur populations in heathland at Noosa National Park and Fraser Island, Queensland, Australia.

1. Reduced bird visits lower seed set of
Banksia robur in fragmented
heathland
Rachele Wilson

2. 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/

3. 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

4. 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

5. 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

6. Methods: site selection
 Two coastal heath
sites (intact and
fragmented)
 Five replicate plots
(20 × 5 m) per site
 At least three
flowering plants per
plot
West of Dilli Village,
Fraser Island (Intact)
East Weyba Section,
Noosa N.P. (Fragmented)

7. 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

8. 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.

9. 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/

10. Visitation rate
0
2
4
6
8
10
12
14
16
18
20
Intact Fragmented
Meannumbervisits/20min
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

11. 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
Meandurationofvisit(sec)
Site

12. 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
Meanpercentvisitswithinter-flower
travel(%)

13. 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 Fragmented
Meanseedsetperfruit
Site

14. 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

15. Lower fertility
 22% reduction in
average seed set
 changes in
pollinator activity
 disruption to
pollination
services
 limited seed
production

16. 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

17. 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

18. 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

19. Questions?
 Special thanks to:
Prof Helen Wallace
Ilee Sannholm
Marvin Scheiffer
Laura Simmons
Dr David Walton
Image (right) courtesy of Laura Simmons