journal of the bromeliad society 1999 mar-apr

8/6/2019 Journal of the Bromeliad Society 1999 Mar-Apr

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JournalTheBromeliad Societ


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Temporal Variation in Herbivory of a PeruvianBromeliadMargaret Lowman1,Michael Brown2,Arthur Desrosiers2,and D.C. Randle2

H rbivory in bromeliads in forest canopies is reportedly rare (Benzing 1990)It is not know n, however, whether this is due to the toug hness of the foliagethe below-average nutritive qualities of the foliag e; their m utualistic relationshipswith protective insects such as ants (that may ward off herbivores); the relativepaucity of herbivores in tree crowns; or perhaps the logis t ic diff icult ies oaccess ing canopy bromel iads to measure them. Al l of these hypothes izedexplanations require extensive field data collection to reject or accept, and nonehave been studied to da te.

Over the past ten years, canopy access techniques have been developed thasolve the logistic challenges of canopy access (Lowman and Nadkarni 1995Lowman and Wittman 1996). One of these techniques is the construction ocanopy bridges and platforms so that researchers and visitors can walk throughthe treetops with ease (Low ma n and Bouricius 1995). One such structure wabuilt along the Amazon River in Peru by a consortium of institutions calledACEER (Amazon Center for Environmental Education and Research) . Thiwalkway extends over 400 meters in length and rises into the canopy at a heighof up to 30 meters.During 1995, the ACEER canopy walkway was used to m ake the f irsmeasurements of bromeliad herbivory in tropical forest canopies (LowmanWittman, and Murray 1996). The average leaf surface area loss to herbivores wa10.4%, which was significantly higher than the negligible amounts that had been

predicted in the literature. We wondered if this were the result of an unusuainsect outbreak event, or if such levels were incurred by the brome liads each yearIn order to test our hypothesis, we re-measured the same bromeliad populationtwo year s l a te r, in 1997 , to com pare the leve l s o f herb ivory to ou r f i r smeasurements and to see whether herbivory had returned to a negligible level.We re-sampled the same population of Aechmea na l l y i L.B. Smith, arelatively rare epiphyte found only in patches of rain forest within the northeascorner of Peru (Luther, personal com mu nication ). This plant grows as a rosette o


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Table 1.Herbivory (% leaf area mined or missing) of Aechmea nallyi 1997

PLANT

each of five plants w ithin c lose proximity to the walkway.Herbivory in 1997 averaged 9.0% (see Table 1) which was almost identicto the 10.4% leaf area losses measured in 1995. Herbivory ranged from 5.9%

12.9% for individual plants, which was similar to the range of 5.3% to 17.3recorded in 1995. It would appear that this bromeliad species suffers moderaamounts of foliage loss to insects each year, and the damage recorded in 199

GRAND 9.0

LEAF1234567

910MEAN

MEAN

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6.7

(2)20128

1520118

81215

12.9

(3)5645

I 3 l68

10 184

5.9

(4 )5

10128

15209--545

11.3

(5)46

1258

128

98

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ACKNOWLEDGMENTSW e a r e g r a t e fu l t o t h e A C E E R f o rproviding canopy access in Peru, and toI n t e r n a t i o n a l E x p e d i t i o n s f o rorganizing the logistics of our visit. Wealso thank Harry Luther for editiag ourmanuscript, and Ellen Baskerville fortechnical assistance.

LITERATURE CITEDB e n z i n g , D . H . 1 9 9 0 . V a s c u l a r

E p i p h y t e s . C a m b r i d g eU n i v e r s i t y P r e s s , C a m b r i d g eUK.

Lowman, M.D. and B. Bouricius. Theconst ruc t ion o f pla t forms andbridges for forest canopy access.SELBYANA 16(2): 179- 184.

Lowman, M.D. and M . Moffett. 1993.T h e e c o l o g y o f t ro p i c a l r a i nf o r e s t c a n o p i e s . T R E N D S INE C O L O G Y A N D E V O L U T I O N . 8 :104-8.

Lowman, M.D. and N. Nadkami. 1995.F o r e s t C a n o p i e s . S a n D i e g o :Academic Press. 624 pp.

L o w m a n , M . D . a n d P . K . W i t t m a n .1996. Forest canopies: methods,hypotheses and future directions.A N N U A L R E V I EW E C O L O G Y A N DSYSTEMATICS 2 7 5 5 - 8 1 .

Photograph by Meg LowrnanFigure 19.

The ACEER walkway in Peru providesaccess to the b romeliads for measurementof herbivory.Lowman, M.D., P.K. Wittman and D.Murray. 1996. Herbivory in a bromeljad o f the Peruvian rain forest canopy. J . BROMELIADSOC. 46: 52-55.

Marie Selby Botanical GardensSarasota, Florida

journal of the bromeliad society 1999 mar-apr

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