Litter decomposition and Ectomycorrhiza in Amazonian forests

18 Pages·2016·4.68 MB·English

by  Ricardo Marenco

Litter decomposition and Ectomycorrhiza in Amazonian forests
1. A comparison of litter decomposing and ectomycorrhizal Basidiomycetes in latosol
terra-firme rain forest and whité podzol campinarana
Rolf Singer (*)
lzonete de Jesus da Silva Araujo (*)
Abstract
lNTRODUCTION
Application of a mycosociological method
lt had been assumed that ectomycorrhiza
(adaptation of the Lange method) in Central
Amazonia produced the following results: In the in the neotropics ls restricted to 1) secondary
white-sand podzol campinarana type of forests the forest and partially destroyed or damaged
dominant trees are oblígatorily ectotrophically tropical and subtropical forests (cicatrizing
mycorrhizal; litter is accumulatea as raw humus mycorrhiza), 2) to the natural vegetation above
as a consequence of ectotroph dominance; fewer
a certain altitude in the Andes and pre-Andine
leaf inhabiting litter fungi occur in the dry as
tropical-montane zone, 3) plantations of intro
well as the wet seasons tha..'1 are counted in
duced ectomycorrhizal trees, inoculated with
the latosol terra-firme rain forest, and the fungi
of that category are most strongly represented eccomycorrh1za or carryng spores or mycelium
("F-dominance") by other species here than in the with seeds or seedlings, 4) possible scattered
terra-finne stands tested. The ectomycorrhizal trees occurrences restricted to certain genera of
and !ungi are enumerated. On the other hand, in Cormophyta [Salíx was suggested), not being
the terra-finne forest, ectotrophically mycorrhizal
dominant in the tropical rain forest (Singer,
!ungi did not occur in the test plots. The trees are
1963; Singer & Morello, 1960). This assumption,
almost all non-ectomycorrhizal in primary terra
firme forest; here, litter doE-s not appreciably if correct, would, mean that the neotropical
accumulate as a deep raw humus layer because the humid lowland cannot be expected to produce
considerably higher number o! leaf inhabiting litter anything in the way of a true ectotroph forest
!ungi (ratios o! 4:1 to 4.2:1 in favor cf terra-finne)
excepting secondary forests (capoeira), plan
and greater diversification (a larger number of
tations and possibly forests containing
species) is potentially capable o! reducing more
scattered non-dominant ectotrophic elements.
than the yearly leaf-fall. In this study, a group
of !ungi was · mainly considered which is not This would mean that there is a basic differ
represented in laboratory litter decomposition ence in the composition of the neotropical and
experiments. However, a comparison with un the paleotropical lowland rain forests.
published and published data shows that otir results
However, recent observations by Kreisel
satisfactorily match the experimental and phyto
( 1971) and Fiard (personal communication)
sociological data obtained both with other classes
o! microorganisms and wíth observations in other indicate that in the Gulf area certain types of
regions. The quantity o! litter decomposing !ungi forest contain ectotrophically mycorrhizal
in the folücolous group depends mainly on tne elements {Coccoloba in Cuba, Torrubía in
amount o! precipitation during the last few days
Martinique).
before counting. This does not hold for all
llgnicolous f ungi.. The reasons for this as well a.s Our own recent investigations in the Lower
the mechanisms by which the ectomycorrhizae may Rio Negro region of Central Amazonia show.
reduce litter decomposition rate:; and influence the thât certain vegetation types (campina, campi
nutrient cycling patterns are disc-ussed. The most
nar·ana, igapó) are rich in ectomycorrrhiza
important genera of Basidiom,ycetes involved in
forming fungi, e. g. Boletaceae (Singer, 1978a).
litter decomposition in the Lower Rio Negro forest
Thus, in both hemispheres, certain tropical
associations are enumerated. Possible economic
significance of introducing ectotrophs in the terra soils require for the formation of any kind of
firme forest is indicated. forest the presence of ectomycorrhiza. Canse-
( • ) - Instituto Nacional de Pesquisas da Amazônia, Mall'aus.
ACTA AMAZONICA 9(1) : 25-41. 1979 -25
quently, the anectotrophic "hyiaea" is inter domycetes, Zygomycetes, etc., as well as
mittent, with interspersed islands of ectotroph bacteria, Myxomycetes, and Actinomycetes.
forests where climatic or edaphic (in Amazo worms, Arthropods, higher animais) under
nia mainly the latter) conditions make it various conditions of tropical forests has, as
impossible for anectotrophic trees to obtain far as we are aware, never been made, and
sufficient mineral nutrition unless ectotrophs with the methods available, meets with some
dominate to such a degree as to change the difficulties.
microbiology of the soil completely and intro
Under these circumstances it was felt that
duce what has come to be cailed direct cycling
a method had to be found that at least provides
(Went & Stark, 1968) or "short-cycling" (Har quantitative data on the Basidiomycetes, their
iey, 1977) of mineral nutrients.
numbers, diversity, habitat requirements and
lhe proposal (Singer, 1964) to reclassify dependency on meteorological conditions, their
the forest types of the world in such a way capacity of forming ectomycorrhiza, their fru
that they are first and basically divided into iting periodicity, in fact ali data that could not
two main groups [1) - ectotroph and anec be obtained in laboratory studies. This method
totrophic forests - has been ignored by forest had already been introduced (Moser-method in
ecologists, first because of misunderstandings Europe, North, and South America; Lange
with regard to the term "ectotroph" on the method in Europe) and had now to be adapted
part o-f some mycorrhiza-speciaiists (Meyer, to the conditions of the lowland tropical rain
1973) and secondly because understandably forest. The method chosen - the Lange
the mycological literature is not adequately methoci - was expected to provide the desired
accessible to ali forest ecologists and phyto data and permit comparisons between the
sociologists (2) • latosol -terra firme rain forest and the podzol
The necessity to accept the importance ot white-sand campinarana.
basidiomycetous components of the eco
systems and the usefulness of terms de
MATERIALS AND METHODS
scribing unequivocally the fungus-cormophyte
symbiotic associations at the levei of the
The Lange method ( 1948) was introduced
individual (ectotroph) and the plant-fungus for the study of fungus sociology in Danish
community (ectrotroph forest) has, in the Sphagneta whereby, in contrast to the Moser
menntime, become ever more obvious and the method (1959), permanent 1x1 m squares
present study wi 11 show that, without them, an were marked and fructifications periodic3lly
undcrstanding of the phenomena observed is counted. In ou r case one 5x5 m square was
nearly imposs1ble. marked in the primary latosol terra firme forest
With regard to litter decomposition, the 30 km north of Manaus (immediately adjacent
role of the Basidiomycetes is generally under to a hectare of a fully studied (Prance et. al.,
stood but rarely presented in quantitative form, 1976) forest reserve at EMBRAPA) and regu
principally becauae earlicr investigators were larly observed (in 6-11 day intervals) 37 times
hampered by the intricacies of the taxonomy during a whole year. Furthermore two 5x1 m
involved. On the other hand the experimental rectnngular test lots, one in latosol terra firme
methods tend to minimize the part played by forest at km 45 of the Manaus-Caracaraí Road
Basidiomycetes since in litter samples their and another immediately adjacent in the Re
growth under laboratory conditions is sup serva Biológica de Campina INPA-SUFRAMA,
pressed. A convincing study, or even estimate with three countings (two, at different seasons
of the relative numbers and efficiency of litter of the year coordinated with countings, the
decomposing organisms (Basidiomycetes, same day, in the latosol terra firme forest) .
other Eu-Mycetes including Hypho-and En- The campinarana forest, the relatively most
( 1 ) - An ectotroph forest is one in which the dominant trees are obligatorily ectomycorrhizal. An anectotrophic
forest is one in which the dominant trees are not obligatorily ectomycorrhizal.
( 2) - • Despite this massive documentation plant scientists commonly seem to little heed the phenomenon [mycor
rhiza] and its implications unless they are studying mycorrhizae per se" J. M. Trappe & R. D. Fogel (1977).
26- Singer & Araujo
thoroughly studied one in the Lower Rio Negro clays with exceptional temperaturas or air
(Andcrson, 1978; Anderson et a/., 1975; Lis humidity measured were marked as such for
bôa, 1975; Prar.ce, 1975) is located between later reference. The precipitation data for the
the entrance to the Reserva and the transition test lot at EMBRAPA were obtained hom the
to the more open, true campina-vegetation meteorological station of EMBRAPA (\ess than
further east. In the following text we shall 1 km away) until October 1977, and from then
refer to this lot and the corresponding cam on from that of Ducke Forest (INPA), little
pinarana vegetation in other Rio Negro locali more than 3 km away. During this latter period
ties as CR and to the latosol terra firme rain very minor rainfall may have been local, but
forest as TF. any major rainfall and most minor ones were
The fungi were counted accordlng to the sufficiently widespread so that the figures
carpophores observed and were without diffl registered at Ducke Forest should be con
culty divrded into six main categories, viz. sidered valid for the test lot.
those inhabiting dead dicotyledonous leaves The presence and distribution of ectotro
(foliicolous), those inhabiting dead pieces of phically mycorrhizal fungi was determined by
dicotyledonous wood and fallen branches and the following method: lnside the test plots
sections of fallen tree trunks (lignicolous); intensive search was undertaken in order to
those inhabiting monocotyledonous trash; detect 1) short roots suspected of being
those growing on the basic mineral soil without ectomycorrhizal (these were preserved in
recognizable orgMic tissue (terricolous); alcohol and tested anatomically), 2) carpo
those growing in association with tree roots phores belonging to any of the genera known
(ectomycorrhizal); those growing in associ to be ectomycorrhizal (the surrounding rootlets
ation with algae (basidiolichens) . were then investigated as above) . This search
In order to obtain data on a homogeneous for ectomycorrhizal fungi was not restricted to
group of litter decomposing fungi, ali Dis the test lots but was extended to the whole
comycetes and carpophore-producing Basidio surrounding area so far as it belonged to the
mycetes were counted excepting the lignico same type of primary forest. The search
lous category and the fungi associated with outside the test plots was supplemented by
alg3e; in the lignicolous category Aphyllopho occasional observations and collections by A.
rales were excluded. and in the lichens ali but B. Anderson and T. V. St-John.
Basidiolichens were excluded. The fungi
counted are exactly those that are probably RESULTS
overlooked in traditional phytosociological
A. The lato sol terra firme forest (TF) - The
work as well as in laboratory experiments. They
Cormophyta individuais which contributed to
were identified, as far as possible to the
the litter of the TF test plot I (30 km N of
species, and in ali cases to the genus; speci
Manaus) and/or penetrated the lot which their
mens of each species were deposited at the
roots are the fottowing :
HerbMium of INPA, Manaus.
Araceae: Anthurium sp.
The meteorological data corresponding to Bignoniaceae species
a 1·, 2-, 3-, and 6-day period preceding the Bombacaceae: Probably Bombacopsis nervosa
actual count (in the morning between 8AM and (Vitt.) Robyns
11 . 30 PM) were restricted to precipitatlon : Scleronema micr8nthum Ducke
since in the ·interior of the foreot precise data Chrysobalanaceae: Licania sp.
on soil temperature and humidity of the air Duckeodendraceae: Duckeodendron cestroides
immediately above the soil were not available Kuhlm.
and did not appear to influence fungus growth Euphorbiaceae: Mabea sp.
equally in ali str~ta and substrata involved nor Lecythidaceae: Eschweilera sp.
did they vary appreciably except as a functlon " : Corythophora rimosa W. Rodr.
of precipitation. Wind velocity never reached Leguminosae (Caesalpinlaceae): Eperua sp.
sufficient force or duration inside the forest " (Mimosaceae) : Pithecol!obium
during the observation period. Nevertheless racemosum Ducke
Littcr decomposition ... -27
Melastomaceae: Miconia sp. Sterculiaceae: Theobroma sp.
Meliaceae: Trichilia sp. In the test plot at km 30 (test area I) in TF,
Moraceae: Brosimum sp. the year-round survey ot I itter decomposers
Myristicaceae: Viro/a ? e/ongata Warb. yielded the results given in table I.
Myrtaceae species In the test plot at km 45 (test area 11) in TF,
Palmae: Bactris sp. two surveys were made with the specific aim
" : Astrocaryum acaule Mart. and A. sp. of comparing, under equal conditions, the
Rubiaceae: ? Coussarea sp. survey of test area 111 on CR (see chapter B,
Sapotaceae: Eremo/uma sp. below). This result can be found in table 111.
" : Pouteria sp. B. The campinarana (CÃ) - The Cormophyta
The Cormophyta of the latosol TF test lot 11 whose roots crossed or entered test plot 111 in
(km 45 of the road Manaus-Caracaraí) with CR or contributed to its litter are the following:
roots reaching into and/or contributing to the Annonaceae: Annona nítida Mart.
litter on the surface are the following : Apocynaceae: Tabernaemontana rupico/a Benth.
Araceae: Phi/odendron sp. Guttiferae: Clusia sp.
Burseraceae: Protium sp. Leguminosae (Caesalpiniaceae): A/dina hete
Chrysobalanaceae: Licania /atifolia Benth. ex rophylla Spruce
Hook. ex Benth.
Parinari sp. : Swartzia do/ico-
Leguminosae (Papilionaceae): Derris flor/bun- poda Cowan
da Benth. Linaceae: Roucheria punctata Ducke
Linaceae: Roucheria punctata Ducke Myrsinaceae: Conomorpha sp.
Melastomaceae: Miconia sp. Myrtaceae: Myrcia servata McVaugh
Myristicaceae: Viro/a sp. : Eugenia sp.
Myrtaceae species Ochnaceae: Ouratea spruceana Eng/.
Musaceae: Heliconia psittacorum L. f. Sapindaceae: Matayba opaca Radlk.
Rubiaceae species (incl. Psychotria sp.) Simarubaceae: Simarouba amara Aubl.
Sapotaceae species The surveys of the litter decomposing fungi of
: Micropholis sp. test area 111 will be found in table 11. Table 111
TABLE 11- carpopllore count in plot UI. CR, carpophores per spccies (ca/sp.), and F-dominnnce -
compared with a carpophore count in a Patagonian ectotroph forcst (Singer, 1971).
1. 2. 3. Nothofagetum
Average
28 li 19'78 (maln 5 IV 1978 (mai n 10 VIII 1978 ( dry (N. pumilio>
CR
rai.ny season) rainy season) season) 1964 1)
l
Foliic. 33 25 8 22 20.9
Lignic. 11 11 8 10 5.1
Ectomyc. o 1 o 0.3 8.9
Total 44 37 16 32 39.2
Foliic. ca,tsp. 3.3 3.6 4
Lignic. ca;sp. 1.8 1.8 2
Folilc. F- .Myceoa osmundi- M.ycena osmundi- M.ycena microlcu.
dominance cola var. (14) cola var. (16) ca (15.2)
Lignic. F· llemimycena. Hem.imyccna. Crepidotus sphnc-
dominance spec. 04) spec. (5) rosporus (6.6)
1l Doto here odJustcd to 5 m2 surfoce os used in plot 111.
28- Singer & Araujo
shows the data obtained when test area 111 in nearly ali cases can be explained by some
(CR) was compared wíth test plot 11 (TF) in special factors entering in specific surveys
order to obtain, under equal meteorologicat such as exceptionally violent and abundant
conditions comparable figures for both CR rainfall (which is contraproductive to fruiting
and TF. especially during the "summer"; this does not
necessarily mean that the mycelial activity
C. Dependence of fungus growth on preclpl during such periods is diminished), possibly ·
tation - Our chart (fig. 1) clearly shows that also exceptionally high air humidity in the test
there is a strong dependence of fungus growth, area (which is favorable for fructification) .
as measured by carpophore production, on the There is also some influence of precipitation
amounts of precipitation. There is no pro on the number of carpophores produced by
portional rise of carpophore production but lignicolous and terricolous fungi but in this
mostly an increase with higher, a decrease case the dependence is not, as in the foli
with lower amounts of precipitation. The icolous fungi, primarily on the amount of
clearest dependence can be demonstrated by rainfall during the preceding day, but on that
the absolute number of carpophores and the of a longer period preceding the appearance of
number of carpophores per species in the the carpophores. The reason for this will be
foliicolous category (fig. 1) . There are even discussed in Critic. But dependence on
here occasional irregularities which, however, avaílable humidity in and on the substratum
TABLE UI - Comparation dat.a on carpophore and species counts in adjacent CR (plot 111) and TF (plot
11) test areas.
CR TF CR/TF ~ CR TF CRj TF CR TF CRj TF
:x
S IV 78 S IV 78 S IV 78 10 VIII 78 10 VIII 78 10 VIII 78 X X
-
To,t al carp. 36 163 1:4.5 16 40 1:2.5 52 203 1:3.9
, species 13 17 6 1~
carpJspecies 2.8 9.6 2.7 3.1
I
Foliicol. carp. 25 106 1:4.2 8 32 1:4.0 33 138 1:4.2
,
species 7 8 2 8
,
carp./sp. 3.6 13.3 4 4
,
% of Total 69.45 64.98 50 82.5
Folücol + Te,r ric. ca. 25 107 1:4.3 8 3~ 1:4.13 33 140 1:4.2
" sp. 7 9 2 9
, ,
ca/sp. 3.6 11.9 4 3.7
,
% of Total 69.45 65.03 50 82.5
Ligni..c ol. carp. 11 54 1:4.9 8 1 1:0.88 19 71 1:3.7
species 6 '1 4 4
,
.carpJsp. 1.83 7.71 2 1. 75
,
% of Total 30.56 33.1 50 17.5
Terricol. carp. o 1.0 0:1 o 1.0 0:1 o 2 0:2
Mycorrhizal carp. 1 o 1:0 o o 0:0 1 o 1:0
Dominant species % of
Total 44.4° 22.7+ 22.5+
( • ) Myccna osmundlcola
( +l M)·ccna polyadclpho
LiHer decomposition ... -29
190
0
180
170 • _. _ f CIS X lO
-0- Fo CA;2
160 · --PREC. PREV. OAY IN mm 0
ISO
·~
la() 0 0 0
_...,
'
120 ( I lj
I li
110 'I I 1\ II ,I, 0 0 .II I I '
100 ' I' II ' \ ' I li 11 ' '' 0
' 'I I " II I \ -e I I I1 ( /'
I
70 II lIi 'I
I I
I
'·
50
40
0 o
30
~/
20
lO
o I 2 3 • S 6 1 8 g 10 11 12 13 1t IS 16 17 11 I' 20 21 ll l3 H 25 26 l7 28 ~? 30 Cll 3Z 33 J<f 35 36 IH
Fig. 1 - COmpanson of prccipitation during the day previous to counting date :md fruiting (folücolou~
carpophorcs - Fo Ca, and foliicolous carpophores per species - Fc/s) in TF.
is quite obvious inasmuch as during the driest D. F - dominance (3 This h as been es
) -
periods of the year there is also a decrease in tablished at every single survey date for the
carpophore production in ali categories. On the two most important categories (foliicolous
other handl one of the interesting results of a and lignicolous) . Excepting those surveys that
year-round survey is the observation that in produced such a small number of carpophores
ali test areas there is even in relatively dry in either of the categories that the data could
perioas of the year, interrupted In 1977 (as in not be considered statistically significant,
many years) by a short secondary rainy season, there was a certain consistency in the F-domi·
never a complete stop of carpophore pro nance of Mycena polyade/pha in TF and M.
duction which means that the mycelial in ali osmundicola in CR, each species being most
categoriesl continue their activity without commonly encountered and most evenly dis
interruption, even though in summer to a lesser tributed in the respective test areas, and thcir
'degree and with the participation af species total numbers in ali surveys to·gether being
normally not fruiting in the main rainy season. higher than those of other species. Ou r data
( 3) - We use, to be precise, the term F (ruitíng)-domlnan ce for the dominance in numbers and density. determined
by the carpophores rather than by the extenslon o f the mycelia in a given tungus associatlon. F-dominance ls
not an ldentlcal but an analogous term compared to the term domlnance o f Cormophyta In pfiy"tosociology.
30- Singer & Araujo
show that F-dominance is not constant during which macromorphologically and anatomically
different periods of the year (different proved to be ectomycorrhizal belonged to a
• aspects "). in different forest communities gymnosperm liana (Gnetum sp.) which is
(TF and CR) cf. fig. 2 and table I. certainly not dominant, but on the contrary,
scattered to rather rare in TF. The other root
E. Presence and absence of ectotrophic
found to be ectomycorrhizal belonged to Neea
mycorrhizae - Our study shows that ectomy
sp. (4 These data lndicate that TF is, although
) •
corrhizae are present in the test area in CR,
scattered ectomycorrhizae occur, not an
absent in the test areas in TF. The negative
ectotroph forest but an anectotrophic forest.
result in the larger test area I (TF) suggests
that TF does not contain ectotroph elements The characteristic, bright yellow clamp
but a search through the entire I ha stand bearing, mycelium farming the ectonwcorrhiza
produced in two cases roots with ectomycorrhi in Gnetum .sp., first collected by T. V. St-John,
za and in two more cases carpophores of was subsequently also discovered in CR, and
genera believed to be generally ectomycorrhi tentéltively identified as belonging to Sclero
zal (Amanita craseoderma Bas and Russulv derma slnnamariense Mont.. Only physiological
puiggarii (Speg.) Sing.) . Onc of the roots studies can determine whether this is a
ISO
·-MY<:ENA POLVADE~LPHA
140 -----M. XANTHDPHYllA X S
130
120
110 1
I» •
90 J
90
;o
$0 •
:•
I I ti 'I
1 I I I ,I I
·- I I I I I
.lO 1 ·, , II II Í' I .
,,
\ I ' I I I '· I '
I I I \ ,\ I I \
I, ' I \ ·- f \
' I 'I ' I
O I 2 :1 4 5 6 1 11 ' 10 11 12 13 1+ 15 16 17 18 I 9 20 Zl 22 23 2'1' 25 26 27 28 29 30 :SI 32 33 3~ 35 36 31
F!g. 2 - Number of carpophores of two representativa species of foliicoious !ungi durlng 37 count.s in TF
(for correspondlng meteorological data compare fig. 1 and table I).
( 4) - Neea (Nyctagln-acae) forms clcatrlzlng mycorrhlza where root-damage occurs, especlally In secondary latosol
forests.
Litter decomposition ... - 31
mutualistic or a pseudomycorrhizal relation • Amanita xerocybe Bas
ship but the apparently constant association Bolete/lus ananas (Curt.) Murr. var. minar
Gnetum/ Basidiomycete sp. in primary forest ined. (type variety widespread)
suggests the former. On the other hand, in *Cantharellus guyanensis Mont. (widespread)
the CR and shaded campina, obligatory Cortínarius (subgenus Cortinarius) sp.
ectomycorrhizae are not an isolated occurrence Cortinarius (subgenus Telamonia), four
but are represented by numerous obligatorily species, collections B 11021, B 11026,
ectomycorrhizal mycelia and carpophores, B 11026a, B 11313.
connected with severa! tree species ali through Craterel/us orinocensis Pat. & Gaill.
the area and are particularly and specifically (widespread)
present on the dominant trees (Aidina hetero Fistuline/la campinaranae Sing.
phylla Spr. ex Benth. and probably also other *Hebelomina amazonensis Sing. ined
Leguminosae such as some Swartzia and lnocybe (subgenus lnocybe) sp.
·Ep erua spp. as well as Sapotaceae, specifi Lactarius amazoniensis Sing. ined.
cally Glycoxy/on inophyllum (Mart. ex Miq.) Lactarius annulifer Sing. ined.
Ducke) . The ectotrophic element is also repre· Lactarius brasi/iensis Sing. ined.
sented in test area 111 (CR) and is abundantly * Lactarius reticulatus (Berk.) Sing. lalso in
present in other campinarana forests along the igapó).
road to Caracaraí (km 114-5, km 125) which Lactarius venezuelanus Dennis (widespread)
belong to the same general type of ectotroph Phyllobolites miniatus (Rick) Sing.
forest although they may well be described as (widespread).
different subassociations or associations ot Phylloporus gymnocystis Sing. ined.
the campinarana type because they are flo Porphyrellus olivaceus Sing. ined.
ristically and in soil characteristics somewhat Russula ? orinocensis Pat. (widespread)
different from the area 111. A list of the fungus Russula puiggarii (Speg.) Sing. (widespread,
components of ectotrophs observed in ali. cam also in igapó and secondary forest - only
pinarana forests investigated is given below facultatively mycorrhizal)
(those with asterisk (*) demonstrably linked *Russula nanei/a Sing.
with Leguminosae or Sapotaceae; the rest *Russula pachycystis Sing.
expected to be ectomycorrhizal because of Strobi/omyces pauper Sing. ined.
taxonomic position and occurrence restricted *Tylopilus arenarius Sing. & I. Araujo
to campina, campinarana and black-water inun Tylopi/us potamogeton Sing. & I. Araujo (also
. dable forests subject to inundation (igapó) in campina and igapó).
and growing under Leguminosae and Sapota- • Xerocomus amazonicus Sing. & I. Araujo
ceae, or because they were demonstrably Xerocomus aff. brasí/iensis (Rick) Sing.
linked with gymnosperms or Psychotria roots}: * Xerocomus g/obulifer Sing. ined.
Xerocomus scrobiculatus Sing. ined.
GASTEROMYCETES: The seemingly small representation (little
over 1% of the carpophores counted and
Mycelium, ectomycorrhizal with Gnetum cf.
scarcely 3% of the species observed) of the
paniculatum Spr. (also in TF) . Scleroderma
36 species enumerated above within the test
sinnamariense Mont..
area 111 is obviously not due to the scarcity of
the total biomass since everywhere including
APHYLLOPHORALES:
test area 111 ectomycorrhizal shortroots were
numerous (although in obligatory as well as
Sarcodon atroviddis (Morg.) Banker
cicatrizing mycorrhizae we find the root system
(widespread).
of a·n individual ectotroph of Amazonian prima
·ry as well as secondary forest is not con-
AGARICALES:
sistently shortroot-like) . The reason for the
Amanita campinaranae Bas scathered fruiting may be attributed to three
f:
Amanita sulcatíssima Bas (widespread) factors: (1) ectomycorrhizal fungi produce,
Singer & Araujo
32-
especially in the tropical rain forest, much Dr. K. Dumont who (personal communication)
larger carpophores than most litter fungi; in finds a much stronger rep1·esentation of
the tcst area 111, one carpophore of Xerocomus Discomycetes in general in the tropical-mon
amazonicus equals, by dry weight as well as tane forests and in the lowland forests closer
by volume, the sum of ali other carpophores to the Andine chains as well as in the sub
collected and counted that day; (2) the corre tropical forests. Likewise Gasteromycetes and
sponding volume of substratum reached by the Aphyllophorales, although often encountered:
hyphae of the individual mycelíum of the represent a definite minority among the litter
carpophore of an ectomycorrhizal fungus decomposing foliicolous fungi.
carpophore is considerably larger than that of
Among the terrestrial fungi, the genera
the non-mycorrhizal species (since there is an
Lepicta, Rhodophyllus, Hygrocybe, Conocybe,
obvious proportional relation between the mass
Callistodermatium are prominent. lt is re
of the carpophores and the extension of the
markable that in Amazonia in general, hypo
mycelium); (3) the observations in campina
geous fungi and "secotiaceous" Basidiomyce
rana as well as in other ectotroph forests
tes are so poorly represented that until now
(Lange, 1948; Singer, 1971) show that ecto
not one specimen has come to our attention.
myccrrrizal fungi do not fruit - as many
Among the Basidiolichens, only one species,
saprophytes do - continuously or in a suc
Multic/avula sp. is common.
cession of "flushes" - but appear solitarily
We have not counted and incorporated in
or in small groups at longer intervals ali
our charts the insect-parasites (Ciavicipitales
through the rainy season, especially at the
and Deuteromycetes) and endotrophically
beginning and towards the end of the rainy
mycorrhizal Basidiomycetes (orchid mycorrhi
season, because the living root, their carbohy
zae) and Zygomycetes (VA-mycorrhiza). Ali
drate source, is continually available during
three categorias do, however, occur in ali test
the whole year and independent of the con
areas, in varlable numbers and different host
ditions modifying their capacity of producing
specialization (see Discussion) .
enzymatic cellulose breakdown.
In the lignicolous group, the genera most
F. ldentity of the fungi observed and their frequently founú are aside frcrm, again Mycena,
ecological specialization - A list of ali the Marasmius, Hemimycena, Marasmiellus, Hy
species occurring, the quantity observed in dropus the tollowing: Lactocollybia, Gerrone
each survey in test areas I, 11, and 111 has, with ma, Collybia, Polyporus, Pyrrhog/ossum, Stlg
the exception of the ectotroph-forming species, matolemma. While we did not take into con
thus far not been completed. These data as sideration any non-Agaricales in this category,
well as the data available on host specia it should be noted that the number ot aphyllo
lization are now being collected for the second phoraceous lignicolous species in TF was as
part ot this pape r. For the purpose of the a whole lower than that of the Agaricales, with
present part they are not essential. lt may the exception of such prominent species as
however be mentioned here that the genera Amauroderma sp. and Caripia montagnei
observed most commonly in the foliicolous (Berk.) O. K., the latter also very common in
~ategory are : TF and CR. This is in contrast to the promi
TF test areas: Myceng, Marasmlus, Hemimyce nence of lignicolous Aphyllophorales in freshly
na, Marasmiellus, 'Gioiocephala, Hydropus. cut or bumed primary as well as in secondary
CR test area: Mycena, Marasmius, Hemimyce forests, on construction wood, lumber piles,
na, Marasmlellus, Hygrotrama, Clavulinopsis. fences, etc.
Althouyh we have registered in the foli Specialization is generally high as far as
icolous category a wide spectrum of fungus habitat categorias (foliicolous, lignicolous,
famílias, it is remarkable that the Agaricales etc.) were concerned, and we found no diffi
are most strong\y represented. Helotiales culty in classifying the Basidiomycetes in
were poorly and Pezizales very poorly repre habitat-groups. This is not only interesting but
sented. This observation is corroborated by also fortunate insofar as it permits precise
IJtter decomposition ... -33
separate counting for each category and reasons. In the fungi this situation is ex
reveé:ls a specific pattern of behavior of each pressed by the fact that terricolous fungi are,
category with regard to mycelial deveiopment, if not abundantly or consistently, but un
carpophore production, dependence on precipi doubtedly present as a definite category in the
tation, etc. The relatively high percentage of TF while what may come closest to this habitat
lignicolous fungi in the tropics has been indi group in CR may be termed humicolous.
cated before (Watling, 1977). lt is also oovious Humicolous mycelia are found in the \ower
in our tables where the lignicolaus carpopho stratum where sand particles are mixed with
res comprise one quarter to one half of the alread deformed or small fragments of rotting
total in CR while more or less one eight af the leaves or pieces of wood, recognizable as such
carpophores are lignicolous in the corre but not further identifiable. We registered such
sponding (i. e. ectotroph) forests of the fungi as foliicolous respectively lignicolous.
temperate zone of South America (Singer, The lack of exposed earth in CR also explains
1971; Singer & Moser, 1965). Only very few the absence ·or scarcity of basidiolichens.
species are both lignicolous and foliicoious.
lt is also well established (Anderson, 1978)
Mycena po/yadelpha, occurring predominantly
that the number of species of phanerogams is
on Jeaves, grows also occasionally on small
smaller in the white sand stands than in the
pieces of dicotyledonous wood. Mycena os
terra firme forests which also finds its ex
mundJco/a (sensu lato) occurs frequently on
pression in the enumeration (see Results)
both Jeaves and wood, but may be a hetero
of host species in the test lots in TF
geneus taxon since populations vary in minar
anci in CR. In TF it is impossible to find any
anatomical and pigment characters, yet only
single species or even gemus that may qualify
one character combination is found in each,
as dominant and only a group of tree species
either foliicolous or lignicolous population. This
treated as a unit may be termed leading since
observation was also made by A. H. Smith
their combined individual representations are
( 1947) . In contrast to a statement by Watling
most numerous and produce the largest
(1977) we know of no example where a
biornass, root extension, and litter in a given
saprophytic speceis, terricolous in the temper
stand of primary forest. In CR, on the other
ate zones, would be lignicolous in the tropics.
hand, dominant species may be determined
An exception ta this rule may be seen in the
(Prance et. ai., 1976). The average height of
fact that ectotrophically mycorrhizal fungi
the trees is greater in TF than in CR, and partly
which are only exceptionally lignicolous in
as a consequence of this but also because of a
temperate zones very frequently ascend on
different pattern of leaf shedding, the number
standlng living or dead trunks in the neotropics.
of leaves shec! during one year is apparently
However, their established or assumed ecto
smaller in CR than in TF. Less leaf shedding
trophy suggests that the mycelium, at least in
per surface unit compnred with greater litter
its mycorrhizal state, penetrates the soil under
accumulation in CR thê.n in TF is remarkable
neath so that it is in contact with the roots.
and can only be attributed to a lesser degree
of activity of litter decomposing fungi in CR
COMPARISON BETWEEN TF AND CR than in TF.
A. Habitat - lt is well known (Prance et ai., Furthermore, the floristic composition of
1976; Singer, 1978) that the litter in the white campinarana-type forest and latosol terra firme
sand stands of forest accumulates to form a forests is different (Prance et a!., 1976), as is
deep, soft layer not exposing the mineral soil also shown in the enumerations of species
whereas in the clay soils of terra firme forests influencing the substartum in the three test
no such accumulations of litter and raw humus plots (see above) . While there is a small
occur and the mineral soil is exposed over number of species common to both commu
large areas or merely covered by freshly fallen nities. the majority of the species is specific
leaves; an accumulation of leaves and wood for one or the other community, and the
occurs only in some depressions or other number of genera common to both is relatively
restricted places for purely mechanical smat:.
Singer & Araujo
34-