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Elevational patterns in predation,
herbivore performance and
herbivory in hostile and enemy
free space
Katerina Sam, Bonny Koane,
Peter A. Konga, Lucia Chmurova,
Vojtech Novotny
Biology Centre CAS, Institute of Entomology, Czech Republic,
The New Guinea Binatang Research Center, Papua New Guinea
[email protected]
HYPOTHESES
• Bats, birds and ants are important predators
• Predators can enhance plant growth by reducing
abundance of herbivores
• Strength of such trophic cascades are often variable both
within and between communities
STUDY SITES
Mt Wilhelm – Papua New Guinea
1200
200
700
2200
1700
3700
3200
2700
8 study sites separated by 500 m elevational distance, from 200 to 3700 m asl
STUDY SITES
Examples of the forest
type at each study site
METHOD
Treatments
Main experiment: 80 saplings (DBH = 10 ± 2.5 cm; ca. 3 – 4 m high) per elevational site
4 treatments – 20 saplings each
1) Control
2) Ant removal
30 cm
3) Ant + vertebrate removal
In separate experiment at 200, 700,
2200 and 2700 m a.s.l
5) Bat removal
6) Bird removal
(+ Control)
- cages pulled up and down daily
4) Vertebrate
removal
- permanently
placed cages
2x2x3m
METHOD
Saplings selected, treated and exposed for 176 ± 8 days
Two collections made within a year
2014
2014
2015
1. Collection – non-destructive; all arthropods + ca. 50-100
leaves collected + number of all leaves estimated
2. Collection – destructive; all arthropods + all leaves
removed (tree not cut-down)
METHOD – Arthropod sampling
METHOD – Insect sampling
• Insect identified into orders or families, feeding guilds, age + measured
METHOD – Leaf herbivory work
26,567 leaves analysed from 1. collection from 560
trees
28,389 leaves from 2. collection
Mean total leaf area per sapling = 8.2 ± 3.4 m2
 ca. 4,600 m2 of leaves involved in project
METHODS – Survey of predators
Ant work
Bat work
Bird work
OTHER RELATED WORK – Survey of predators
BIRD SURVEY – 33,639 individuals recorded – 241 species
• 1,354 individuals mist-netted – 105 species, food surveyed
Species richness
9
Abundance
1
BAT SURVEY – similar pattern, ca. 38 species – 496
individuals trapped and 283 “individuals” recorded
ANT SURVEY –
4 sampling methods,
232 species,
7,611 individuals
RESULTS – Insect Total
ALL
(mean±SE)
VER
RESULTS – Arthropods Guilds
(mean±SE)
/
RESULTS – Arthropods Body Sizes
Control
community
(mean±SE)
RESULTS – Herbivory
(mean±SE)
RESULTS – Insect Total
RESULTS – Herbivory
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CONCLUSIONS
• Exclusion of vertebrates has positive effect on
•
•
•
•
abundances of arthropods
- This effect decreases with increasing elevation
Exclusion of ants have little or no effect on abundances
of arthropods
- This effect appears only at lowest elevations
Mesopredators (i.e. spiders, wasps) seems to
compensate for removed predators at low elevations
only
Exclusion of predators changes size composition of
arthropod communities
Exclusion of predators leads to higher herbivorous
damage
THANK YOU FOR YOUR ATTENTION
Follow the project
Web page: http://tvardikova.weebly.com/
Email: [email protected]
Acknowledgements
Staff of The New Guinea
Binatang Research
Center
Numerous village
assistants from Kausi,
Numba, Bundi, Sinopass,
Bruno Sawmill and
Kegesugl for assistance
Czech Science
Foundation Grant 1432024P
Peter Amick
Bonny Koane