-
their assumption that memory Yapacity is
mory
fixed throughout would be false
capacity could be a plastic varia
In conclusion, Brodin and Clark]” present a summary of how they currently believe energy is balanc.74 between fat reserves and hoards in a winter population
of parids. By presenting their ideas in the
form of a model, they are able to make
concrete, testable predictions of the type
of patterns one should be able to observe
in the wild. In the model, Increasing capacity and longevity of memory does not contribute much to the fitness of the individual at the end of winter. This is a direct
consequence of the fact that even fnrgotten seeds still contribute to the food supply, since they are hoar&d in the bird’s
own foraging niche. This in turn suggests
that it may be time to reconsider the function of spatial memory in food-hoarding in
the Paridae.
I-o
818
Dept of Psychology. Uris Hull.
Cornell Universiry. Ithaca. NY 145.53, USA
([email protected])
nterest in the canopies of trees has
increased dramatically in the past five
years’-“. Until recently, the study of this
important biological stratum has been
hindered by a Pack of safe and adequate
access5. One novel method, the canopy
crane, seems to have found utility and acceptance for a wide range of researchers.
By 1998there will be at least seven canopy
cranes in use at forest sites in Panama,
USA, Venezuela, Japan, Australia and
Malaysia.
The first international canopy crane
symposium was held in Panama in March
of this year to discuss how the research of
the increasing number of canopy crane
researchers can be integrated to best
effect. A canopy crane network was established and agreements made on site protocols and minimum datasets to ensure
that the resulting data will be compatible
and will allow global comparisons. The
symposium brought together scientists
involved in canopy research, conservationists, global change specialists and
those involved in the management of
forests. Representatives from the Secretariats of the Conventions on Biological
Diversity, Climate Change and the Ozone
_____~
.__.
-..
Hitchcock,
CL. and Sherry, D.F. (1990)
l,oorg-term
~a~~~
foor cache sites in lbe
ped chickadee, Anrm. BehaL:. 40,
701-712
Brodin, A. (1992)
Cache d~spe~~o~ affects
retrieval time in hoa
Scond
wanters.L A.
e/ Ui C1995) Fitness
conseqtlcnces of h~~~~g behaviour in tire
IEura~i,+nred squlme?, Proc. R. Sot iondon
SW. H 262,X77-281
Vander Wall, S.R. (19X2) Bn experimental
a&ySiS Qf ‘XCk
m&racker,
Anim.
Slaerry. D.F et ul
Incation of stored
recovery in CkUk’S
Behaa 30,84-94
(1981) Memos
Ior
f~oodl In MK&
Pits, Anrrii
Behcu 29, 1260-1266
Cowi;, ILL rf a/. (1981) Food storing by mu-&
tits, :;nim. Behou. 29, 1252-1259
Stevens. T.A.. and KreLs, J.R. (19%) Wetdeval
0% sUowd seeds by mar& lib ~QVUS
palusliris im the fieki, Ibis 1X$513-525
Haftorn. S. (1956) Con~bu~~o~
to tie focd
biology of tits especially about storing oi
§~rplUS hod. Pati 111:me willow tit (Pomr
~~~~co~i~~~s~, K Xorske Vidensk Wsk Skr.
1956, 1-79
Higuchi. H. (1977) Stored
nue
~~st~~~~s~s
c~s~~~~~~ as a food resource cafnestling
varied tits Paws oarius, Ton 16,9-l 2
Layer and other key international statutes
indicated how they saw the canopy
cranes being used to answer critical
global questions. The results of this symposium will be published by the United
Nations Environment Program (UNEP) in
a format suitable for policy-makers,
scientists
and environmental
change
managers.
Why do so many research groups see
cranes as being such a useful tool for
canopy research? Until now most studies
of the rainforest biota and ecosystem processes have been carried out 2t ground
level or from those few points in the canopy made accessible by towers and canopy walkways, and yet it is the canopy where the atmosphere meets the biosphere - where many of the critical
ecological processes take place. Cranes
provide rapid, easy and non-destructive
access to many parts of the canopy for
small teams of researchers. it takes just
seconds from stepping into the three-person gondola on the ground to be lifted up
to the top of any tree. The gondolas ran
carry live power or battery power and
other equipment so that direct measurements and readings can be taken. This
iilow T&G, Ornis
23, 7-12
caches ilnai haw Geen stored by ~at~~~~y
fmagiing wibw Gii, Anrm. Behav. 47.730-732
Brodin. A. and Ekman, J. (1994) Bern&s
food ~~a~~~ag, Nc&re 372,510
Brodin. A. and Clark. C.W. (1
~~a~~i~~ in the Patidae: a d
Behav. Ecol. 8, 178-M
Krehs, J.R. (1990) Food-storing birdsz
of
. .
Smulders,
T.V.
ct cd.(19%)
Seasoaai
iss bi
bird
J. Neurobiol. 27. 15-25
Sherry, D.F. et crl. (1982) ‘I’be spacing
vtiation
ot s&wed
Eood by maash ti&, 2 i”ierp.~.vchol. 58, 153-162
allows researchers to Rave both hands
free to manipulate leaves and branches.
Although pseudo-replication
is potentially a pyobiem for experimental science
using the canopy crane, in practice the
reach of the boom permits multiple individuals of many trees to be accessed and
manipulative experiments, such as shading of branches or raising CO, levels for
individual branches, are highly feasible.
For example, more than 29 tree species
with three or more individuals exist at the
Parque ~etropo~~ta~o site in Panama.
Some of the cranes are operated by fulitime drivers who are expert at returning
to a large number of site locations within
the canopy with pin-point accuracy. Using
smaller narrower one-person gondolas
aliows the researcher to drop below the
upper canopy level to look at sub-canopy
Ievels. Equip~xegt czn be left in the canopy
and monitored at regular intervals.
The first construction crane used for
tropical rainforest research was estab-
City6 (8”59’N, 79”32’W). This crane is situated within sight of the Pacific Ocean and
in forest which has an annual rainfall of
1740 mm with a disi’inct
remarkable success of th
judged by the breadth and novelty of the
science that it has faci!itated. in the six
years since this crane was erected, 75
Copyrighl %r1997. Elsevier Science Ltd. All rights reserved. 0169-5347/97/$17.00 PII: SOl69-5347(97)01205-6 TREE
co/
I.?, nu. I I November
1’997
investigators from 16 countries have carried out co~~aborati~~eresearch in a range
of scientific disciplines.
Research here has focusse
sonality, plant phenology and e
logical relations between plants and the
atmosphere4s’Ia. Recent ~~vest~gat~o~ of
the relationship between leaves and the
upper canopy enviranment indicates that
the opening and closing of stoma&s may
have minimal effect Qn t~~s~~ration in
species that maintain a humid boundary
layer, effectively buffering the leaf from
the dry canopy atmosphereg. The photosynthetic rate of Ieaves in the canopy of
Ficus insipidahas been found to be higher
than that oI Amywild sp
rded,
although researchers s
milar
high photosynthetic r
ound
repeatedly as leaves of other species are
per canopyI”. Perhaps
one of the most remarkable discoveries
is seasonal changes in the morphology of
new leaves prloduced in single tree crowns.
These strong seasQna4 changes adjust
allocation to photo
esis to seaof light and
changes in the availa
water in surprising waysll. Otber groundbreaking research has le
of strong species and seasQn-dependent
emissions 0: volati
tree canopies (M. L
ers. commun.). C_oll
ave worldwide implications that wiP1contribute to the parameterization of giobal
climate models”. None of these studies
would have been possible without the
access provided by the canopy crane.
Canopy craues also provide a means
:Jf more accurately identifying and understanding arthropod diversity in the canopy.
One critical study ofthe host-specificity of
to canopy trees has re
vealed that there is a distinct beetle fauna
lianas of the family Bi*or’
a. Through continuous 0
bivorous beetles feeding
the canopy, F. Odegaard
has found 49 undescribe
dine weevils adapted to hold on to the tendrils of the twelve
’
aceous lianas at the F
means of a groove
Panama Canal some seventy kilometres
ta the north (~‘~7’~,7~‘~~W~. Here the
rainfall exceeds
forest is evergreen
3450 mm a~~ua~~y
averages less than
~~~t~s~ Research has just started at this
site ad with so inany plant species shaped
between the two sites it will be interesting
nd their associated biota
to see how
fferent rainfall regimes.
respond to
ies ofthe bioiogjj 0’ these w~uscat
plbrits
and the organisms asssciated with them.
program, recognized the value of canopy
Littie is understood of the biology of
cranes as tools for scientists to help adthe giant d~pte~oca~~forests typical of lowdress many of the critical science questions
land rainfQrest in Borneo and elsewhere
by a number of the ~~te~~at~o~a~ in south-east Asia west of the W&ce
!ine.
conventions that UNEP ad
For example. untii recently di
example, tbe scientific and technological
were ihought to be pohated
committees
for each of the Conventions
Several recent studies in Tba~~and, Sri
On Biological Diversity, Climate Cnange
Lades, and Malaysialj-li ncswindicate that
and the Ozone Layer have ali set research
bees and many other insects are involved
~r~or~t~es~Many of these involve studies
T. lnoue and colleagues from Kyoto Uniof forests and in particuEar processes
versity, Japan., who previousfy have been
place in the canopy of trees or
studying the biology of some 506)species
between the biosphere (the canopy) and
of trees in dipterocarp forest in the Lambir
the atmosphere.
HilBsNatiornal Park in north Sarawak using
r canopy cranes are currently
an extensive canopy walkway system, will
in Venezuela and the USA. be instaihng a crane of similar size to the
%l
elan crane, located in lowland
Wind River crane in 1998.This multi-access
rainfores’: near La Esmeralda in Southern
canopy system will provide an unparalVenezuela (3~~5’N,64~4~‘W~,is different
leled QppOrtunity to sludy an area of forfrQm the others in that it is mounted on a est with over 1200 species of trees.
150 m length of rail to provide access to a
So little is known about the canopy that
larger area of
This facility, estabthere remain many unanswered questions
lished in 1996,
ts research in plant
from basic inventory as to what is there to
phenoiogy, an
~~tera~~t~o~s,forest
tbe processes that go on there. Erwin Qnce
energy balance, avian community structure
called the canopy ‘the last biotic frontier’,
and frog and o~bopter~ c~~rn~l~icat~o~.
suggesting that two-thirds of all insects are
The only established temperate rainfeund therelg. owever, recen: research
forest crane is the Wind Rive: crane located
on beetles at me intensively studied site in
in the Douglas fir forests c: Washington
Indonesia indicates that most species arc
State (45”49’N,121”57’W). B fh a height of more closely associated with the ground
than the canopylg. Vines remair? virtually
85 m and a jib ! ?ngth of 75 m it is the largest
so idr established for canopy rie unexploved in tropical forests in spite of
the’fact that they m E+ constitute 30% of
, providing access to 320 individual
the canopy. We currently do not have a
tree crowns over 2.3 hectares of forest.
complete understanding of water transAlthough the diversity here is considerport in tall vines which often have large
ably less than at the tropical forest sites,
se1 diameters making the generation of
studies cf other simila
hly negative potentials very difficult.
west America indicate t
of the more interesting phpioiogicai
rich a~~~o~o~ fauna
questions is whether or not water poteainvestigation12. This crane facility, estabtials at the tops of tall trees are sufficiently
already supported
ich have been com- negative to oppose the force of gratity20,”
and studies are now under way at the
pleted, are ongoing or are p!anned for the
Panama and Wind River sites to answer
future. In line with work conducted on the
this question. The new network of canopy
other canopy cranes much of this research
crane facihties will catalyse research pros to focus on canopy tree ecophysioigrams at these sites. A preliminary crosso_gy.Another crane is
lishment in temperate forests in 1998 at site experiment will explore top-down
control of ecosystem function, excluding
the Tomakomai Forest Station of
and other Barge animals from canUniversitjr, Japan.
nd understory sites to explore the
The tropical rainforests of Australia
nses of arthropods. levels of herbivpy less than 0.2% of this con;inent’s
ogr on leaves sod plant reproductive strucmass and yet have a very high proortion of its terrestrial biota; as noted in tures, aind ultimately plant production.
With the continued backing of UI\!EP. the
the successful a~~~~c~tio~for World
network wi91facilitate exchanges of ideas
and investigators and encourage research
in all disciplines.
The United Nations Environment
Pro-
gram, in supporting the STW canopy crane
Heritage forest. Many of the plants in this
area are gondwanan relicsI”, and the crane
wilil provide unparatie~ed access for stud-
Cooperative Reseurch Cenh-e fw
Tropical Rainforest Ecoloa ilnd @kmQg?ement.
James Cook lJniversi@ Cairns Cumpus.
PO Box 6811, Cairns. 4570
Queensland, Australia
Wright. S.J. (lY96) ~~e~ot~~ic~ responses to
seasonatity in tropicat forest &VW in
Tropirul Fwust Plmt Erophwolog~
(Mulkep. S.S.. Chazdon. R.L. and Smith. A.f’..
eds). pp. 440-4tiO. Chapman & Haff
of
s, in
f’arthenon
16 ~Mornose. I<., Nagamitsu. T. and frrour. T.
( 199(i) The regroductive w72ogy of an
emergent dipteroct!rp iraa lowland ~a~~~~~est
in Sarawak, Plonl : ‘1 Bwt 11.
Memzer. F.C. el (I/ (1993) Stomalel and
~m~~~menta~ control of t~~~~~~at~~~ in a
Powhd tropical forest tree, fYu’lunr
CPU
Eflr,ron
some Sk-fLankam diptem
Forest Piunts
Kqroductrue Ecologv of Trap
(Bawa. K.S. and tfadley. M.. eds). pp 10X-134.
1X9-198
16. 429-436
as
pioneer &ee.
F!cus ~n~i~i~~,
Flwu 190,265-272
Kitajima, K., Mulkey. S.S. and Wright, S.J.
Lowman, M.D. and Nadkami. NM eds (199%
Forest Cunopies, Academic Press
Moffett, M.W (1993) The &h FronGer:
Expkmg
the TIq~,pli‘al
Rarnrbrest f~nopv,
Erwin, T.L. (1983) Topical
forest can
e last biotic fronti.er, Bull. Enfomol.
o&ted traits, Oecolop
Hai vard
Stork, N.E.. Adis. J. and Didt am. R.K., eds
(1997) Cunop~Artlrrc~pnd.s, Ciupman & Hall
Allen, W.H. (1996) ~~.ave~n~u~~
across the
Ireetops, BmScluIrc~ 46. 7% - i9?
Winchester, N.N. (1997) Canopy ~~~~~~~~~
elf coastal Silika spruce trees 0~1V:iucouver
a c~~~~~s~~ ol caoaf9y and other ecoPo88e
assemblages in a B\t~;l%nd troopicaf forest in
-2,.!/rropud,s(Stork, N.E.. Adis. J. and Didham,
Salewesi. in Canopy .~rt/wopods (Stork, N.E..
Adis. J. and Didham, R.K.. eds). pp. 184-Z33.
R.K., ~‘(1s).pp. 151-168. Chapman&Hall
Webb. L.J (1990) The tropical rainforest, in
Austrulran Troprcul Rocnforests: Science-b’uturs.Ilr~tm:ng (%‘ebf~, L J, and Kikkawa, J.. eds).
Lowman, M.D. and Moffett. .ii W (1993)
The ecology of itp.CppfraJ
&P forestcampics,
TrmdsEcolEd 8, 104-I( ”
Parker, C.G.. Smith, A.P. ant, hogan. K.P.
(1992) Access ta the upper nrest canopy
pp. f-4. CSIRO
Appanah. S. and Ghan. fi T. (1981) TMps:
a large tower crane, H ~.Scienca12.
~~ysi~~~~~~~~
c~~togyof tropical
forest canopies, Trends Em! Euol. 1I, 408-412
Fororeshy,44.234-25:!
Dayanandan, S. rf (II. (1990) Phenology and
flora! ~~~~~f~~
in relation to ~ott~~a~i~~
a test of tRe ~~~~~c~~~~pressure Bechnique,
Scrence 2iO. 1193-I I!‘4
___treaty on bislogical divertchinson’ noted that ‘In any
tionary ecology, food
lations appear as one of ihe most
portanr aspects of the system of anim
nature. There is quite obviously more to
living communities than the raw dictum
“eat or be eaten” but En order to understand the higher intricacies of any ecological system, it is most easy to start from this
crudely simple point of view.’ Accordingly,
studies of food relations and the underlying dynamic flow of energy and nutrients
betwee -Jorg,utisms have been centrally
importcat for our ~nderst~~~d~ng of ecoI0,~ at .he i~~dividual, population, cor.b
munit) md er:osystem levels and for our
uraderst;mdin,! asfthe evoh tio.n of ecological systems.
Anal her in
what w(tdo nc
ever, that organisms do not assimilate
all the available resources in their food.
This inet’ficiency can result from apparent
phylogeqetic constraints (e.g. passerines
in the Stilrnidae-~nuscicapidatu taxon lacking the enzynl;- to digest sucrose2) or from
compounds in rhe food (e.g. fiber or toxins
::opyrl$~i
@ 1997.
-. --...__
--
in plants) that retard or ini ibit the breakdown and absc rption of ingested nutrienls.
In April, a group of comparative physiologists and anatomists from across the globe
gathered in Rauischhoizhausen, Germany,
to discuss recent advances in the study of
the vertebrate digestive system and their
ecological and evolutionary implications.
The workshop, organized and hosted by
P. banger and R. !%-I es (both of Justusiessen, Germany),
. Starck (Universitiit Tubingen,
equel to one held five
years earlier in Cambridge, UK, which focused on the theme of food, form and function in the digestive system of mammals~.
Mb workshops promoted interdisciplinary investigations into the patterns and
processes of the digestive system; however, the most recent workshop was expanded to include i~terd~sci~l~~ary resear-h on mammals, birds an
Three contemporary th
study of the vertebrate digestive system
were explored: comparative anatomy and
the evolution of the digestive system, form
and function of the digestive system in relation to dietary niche and nutrition, and
Elsevier Science Ltd. Nl rights
Chapman&f-fall
210
Cei/ Enown. 17, 116?‘1--1194
Hotbrook. NM.. Burlis. M.J. and Field, C.B.
( 1995) Plegative xylem pressures in f&an&
the
pollinators of some dipterocaqw, ;Mulqwrn
664-670
Mulkey, S.S., Kitajima. K. anti Wright, S.J.
(1996) Plant
29,14-19
Hammond, P.M.. Sturk. N.E. and BrendeX.
M.I.D. (19%‘) l‘ree-~?rr%n beetles in context:
109,49J-498
reserved.
0169~5347/97/617.00
PII: S~)1695347(97)01201-9
ecological and evolutionary implications
of phenotypic plasticity in the digestive
system.
The first step in Cc analysis JI any bioLogical system is often the description of
morphology and its apparem function,
and the workshop Included exciting presentations about the digestive system of
vertebrate groups for which very little is
known. N. Zhukova (Institute of Zoology,
Kiev. Ukraine) used characters of the digestive system to suggest a close phylogenetic relationship between the fnsectivoral (e.g. moles, s’hrews, hedgehogs),
fin and minke whales revealed remarkable I’unctional similarities to the rumen
of ruminants: slightty acidtc pH (5.3~6.8),
high concentrations of anaerobic bacteria
(some can digest the chitinous exoskeleton
of their invertebrate prey) and the presence of volatile fatty acids.
ementing the presentations on
ive system of less stu
tebrates
were two very informative
reviews of large-scale patterns in gut
form and function. 8. Snipes, f-f.Hornicke
and G. Bjornhag (Swedish University of
Agricultural Sciences, Qpsala, Sweden),
presented an exhaust&
review of t
TREE
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J.997