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Vulinec: Dung Beetles, Monkeys, and Conservation
229
DUNG BEETLES (COLEOPTERA: SCARABAEIDAE),
MONKEYS, AND CONSERVATION IN AMAZONIA
K
EVINA
V
ULINEC
1
Entomology and Nematology Department, University of Florida
Gainesville, FL 32611
1
Current Address: Department of Zoology, University of Florida
Gainesville, FL 32611
A
BSTRACT
Dung beetles are important in several ecological processes, including nutrient re-
cycling, soil aeration, the transport of other organisms, and the burial of vertebrate
dispersed and defecated seeds. Dung beetle species vary widely in their abilities as
seed dispersers. The biomass of beetle species that bury no seeds, bury small seeds
only, or bury small and large seeds, is significantly different among sites along the
Amazon River. The abundance of monkeys that act as high quality seed dispersers
also varies at different sites. Implications of these differences in seed dispersal dy-
namics are discussed. Recent clearing and disturbance of primary forest is having an
effect on the populations of primary and secondary seed dispersers, and suggestions
for conservation of these critical faunas are presented.
Key Words: dung beetles, Scarabaeidae, monkeys, primates, seed dispersal, Amazon,
Brazil
R
ESUMO
Os coleópteros coprófagos são importantes em vários processos ecológicos, in-
cluindo reciclagem de nutrientes, aeração do solo, transporte de outros organismos e
enterramento de sementes dispersadas e defecadas por vertebrados. As espécias de
besouros coprófagos variam imensamente quanto a sua habilidade em dispersar se-
mentes. A biomassa das espécies de besouros que não enterram sementes, a biomassa
daqueles que enterram somente sementes pequenas, e a biomassa daqueles que ente-
rram tanto sementes grandes como pequenas é significativamente diferente entre va-
rios locais ao longo do Rio Amazonas. A abundância de primatas que agem como bons
dispersores de sementes também varia grandemente entre diferentes locais. As impli-
cações dessas difereças na dinâmica de dispersãa de sementes são discutidas neste
trabalho. As recentes derrubadas de ávores e as perturbações de dispersores primário
e secundário, e sugestões para a conservação da fauna são apresentadas.
Dung beetles, an omnipresent component of tropical biotas, perform important eco-
system functions. Several characteristics make this group of beetles ecologically signif-
icant (Hanski & Cambefort 1991; Halffter & Matthews 1966). They are particularly
vulnerable to deforestation and other changes in habitat and fauna, and this sensitivity
makes them useful as indicators of ecosystem health (Halffter et al. 1992; Klein 1989).
As they are primarily associated with mammals, they are also indicators of mammalian
abundance and possibly diversity. Nevertheless, dung beetles’ functions in ecological
systems go far beyond the status of an indicator. They contribute services including, re-
cycling of nutrients, aerating the soil, serving as transport for predatory mites, and
230
Florida Entomologist
83(3) September, 2000
burying of seeds in dung (Hanski & Cambefort 1991; Halffter & Matthews 1966; Es-
trada et al. 1991). Because of these roles, the decline in dung beetle abundance and di-
versity may have cascading effects on the environment. In this paper, I discuss the
results of some of my studies of deforestation, rainforest disturbance, and dung beetle
abundance and diversity. I also present my research on the seed burying characteristics
of different species of dung beetles, and how these differences may effect seed dispersal
in tropical rainforests. Finally, I will discuss rainforest survival associated with seed
dispersal and some suggestions for accelerating recovery from disturbed habitat.
Dung beetles are generally grouped into dwellers, which live and nest within a
dung pat, burrowers, and rollers (Hanski & Cambefort 1991; Halffter & Edmonds
1982; Halffter & Matthews 1966). Dung beetles of the burrower guild dig nests under
dung pats, and those of the roller guild roll the dung away from the site of deposition
to be buried later. Members of both of these guilds pack these nests with dung, usually
formed into balls, and lay eggs in the balls. The larvae develop and pupate within the
brood balls, and emerge as adults (Halffter & Edmonds 1982; Halffter & Matthews
1966). Additionally, most species of rollers and burrowers also make feeding balls that
are buried, may be abandoned uneaten, or if eaten, contaminants (from the beetles
point of view), such as seeds, are often moved underground (Vulinec, 1999). These be-
haviors hasten the decomposition of waste, aid in nutrient recycling, and contribute
to aeration of the soil (Halffter & Matthews 1966). They also reduce pests in dung,
such as dung breeding flies (Bornemissza 1970; Fincher 1981).
Additionally, dung beetles have an important role in seed dispersal. Seeds swal-
lowed by frugivorous mammals are often defecated intact and viable (Garber 1986; de
Figueiredo 1993). Nevertheless, as much as 90% of seeds defecated onto the surface of
the soil may be destroyed by rodents or other seed predators unless buried; this burial
is accomplished almost entirely by dung beetles (Estrada & Coates-Estrada 1991).
However, dung beetles are especially susceptible to ecosystem change (Morón
1987; Klein 1989; Halffter et al. 1992; Estrada et al. 1998). Disturbance of tropical
rainforest may affect dung beetles directly by altering temperature, humidity, or soil
characteristics, or indirectly by reduction in mammal faunas. Disturbance may have
a number of different outcomes. Intensive land use in tropical areas, such as bulldoz-
ing, may result in degradation that will never be reversed (Buschbacher et al. 1992).
On the other hand, less disturbed areas may have the potential to reforest. This re-
bound may be very important in developing management practices for revolving agri-
culture in tropical forests (Fearnside 1993). Studies done in Brazil and Costa Rica
suggest that the most important factor in reforesting land is getting the seeds to the
sites (Young et al. 1987; Pannell 1989; Nepstead et al. 1991; Holl 1999). Primary seed
dispersers such as birds, bats, and monkeys are instrumental in this process (Chap-
man & Chapman 1995. As rodent density can be very high in secondary growth (Chap-
man & Chapman 1999), secondary dispersal and burial by dung beetles may also be
an essential element in reforestation. Habitat characteristics that encourage use by
these dispersers will improve an area’s chance of regenerating natural rainforest.
To determine the effect of land disturbance on populations of dung beetles in rainfor-
ests, I investigated beetle abundance and diversity in three habitats at three sites in the
states of Rondônia, Amazonas, and Pará, Brazil; more specifically, I censused beetle pop-
ulations at the three sites, and in three habitats, primary terra firma forest, secondary
growth, and clear-cuts. I also examined the most common beetles in these habitats for
seed burial capabilities. I asked: What beetles are best at seed burial? Are there limits
to the type of seeds that are buried by different species of beetles? What communities of
beetles occur at each site? Are there differences in the communities of monkeys? What
are the implications of community differences for forest regeneration? Finally, what ef-
fect will development of the Brazilian rainforest have on seed dispersal dynamics?
Vulinec: Dung Beetles, Monkeys, and Conservation
231
M
ATERIALS
AND
M
ETHODS
Sites
I examined dung beetle and monkey communities in three widely separated sites on
tributaries of the Amazon River in Brazil. The land near Caucalandia in the state of
Rondônia, Brazil, is mostly cattle ranches, secondary growth, and some patches of pri-
mary rainforest. Mean annual rainfall is 2300 mm, and mean annual temperature is
27
°
C (Landowner, pers. comm.). The state of Rondonia was undeveloped until the late
1960s, when the government brought in people from the overcrowded cities in the north-
east (Page 1995). This area currently has one of the highest rates of deforestation in the
world. With clearing, erosion has increased, and soil quality has decreased; laterization
of the soil is common. By 1991, over 37,000 km
2
were cleared, more than 16% of the total
state; a good quarter of the state is probably cleared by now (Stone et al. 1991).
My research site here was a small section, 250 ha of primary forest, bordered by
overgrown banana and cacau plantations, and some areas of capoiera, natural re-
growth. Hunting is discouraged on the private land; however, poachers were encoun-
tered in the primary forest area. Even so, peccaries, agoutis, jaguarundi, deer, and
sloths, were often seen. Additionally, monkeys were easily observed. The work at this
site was done between October 1996 and March 1997.
The city of Manaus is located in the state of Amazonas at the confluence of the Rio
Negro and Rio Solimões (Amazon). Rainfall in the area averages 2200 mm per year, and
average temperature is 27
°
C (Salati 1985). The biological station Reserva Adolfo Ducke
(10,000 ha) is 25 km northeast of the city, and is surrounded by land that is rapidly be-
ing developed. Poaching is common, and most of the large mammals have been extir-
pated. Agoutis, which are seed predators, and coati were common, but no tapir or
peccaries have been seen for possibly more than 15 years. Monkeys are the most com-
mon large mammal, but are also hunted regularly within the reserve by people in the
surrounding communities. As these communities often have a higher standard of living
than many parts of the Amazon, this hunting pressure is particularly unfortunate. Two
dead howlers that had been shot and escaped to die later were found during my time
at this site. I worked at Reserva Ducke between November 1997 and December 1998.
In Caxiuanã, Pará, is a recently created biological station (established 1990), the
Ferreira Penna Scientific Research Station. It is located off the Rio Pará at the south-
west side of the Ilha do Marajó. This station includes 33,000 ha, 80% of which is terra
firma forest, and 20% is blackwater floodplain forest (Lisboa 1997). Annual rainfall is
around 3000 mm (Lisboa 1997), however, October is the driest month, the month of
my collection, and the year of my work, 1998, El Niño increased dryness and fire po-
tential all over the Amazon. Surrounding communities of the reserve are sparsely
populated, and hunting pressure is low. Monkeys, especially howlers and the silvery
marmosets, have been habituated to humans by previous research. The upland area
at this site is surrounded by swampy seasonally flooded habitat.
Seed Burial Experiments
The number of dung beetle species was high at some sites (> 50); I tested the most
common species that are large enough to bury at least 5 cc of dung. Beetles not tested
in burial experiments were assigned the same categories as similar sized congeners.
To determine what proportion of seeds imbedded in dung particular species of
dung beetles bury, I used natural seeds or plastic beads that were small (<5 mm) or
large (>10 mm). I placed beetles in mesh-covered buckets (40 cm diameter
´
36 cm
depth) filled with 150 mm sandy soil, and placed 50 cc of fresh cow dung with embed-
232
Florida Entomologist
83(3) September, 2000
ded seeds in the center of each bucket. Buckets were left up for 72 hrs. The number of
individuals of each species varied depending on the size of the beetles, such that bio-
mass of beetles remained approximately equal (Vulinec 1999). Sample sizes varied de-
pending on the number of beetles captured alive.
For smaller species (e.g.,
Sybalocanthon
sp.), I placed beetles in 1-liter containers
with 100 mm sandy soil, and10 cc fresh cow dung containing only small seeds. After
72 hrs., I excavated the burrows, 10 mm at a time. I recorded seeds buried and depth
of burial.
Surveys
Beetles
Using baited pitfall traps set along the same route as the monkey transect, I cen-
sused beetle community composition and species abundance in three habitat types at
each site: primary rain forest, secondary growth (edges of primary forest, old planta-
tions, and previously cleared areas), and clear-cuts. Beetle traps were 1-liter plastic
cups buried to the rim in soil, and topped with a 3 cm aperture funnel. A 50 ml cup
baited with human dung was suspended by wire above the trap (Howden & Nealis
1975; Gill 1991). The volume of dung in the traps attracted even the largest beetles
(Peck & Howden 1984). I set a total of 27 traps each census, which were left up for 24
hrs, then collected. Three traps were set at 20 m intervals at 9 different trapping sta-
tions (3 sites in primary forest, 3 in secondary growth, and 3 in clear-cut). This trap-
ping regime yielded 1242 trap-days (sensu Klein 1989) for the three locations. Each
site was surveyed for nearly the same number of trap-days.
Beetle biomass was measured as dry weight; the beetles were dried at room tem-
perature for 1 week prior to weighing. Ten individuals of selected species, those most
common, were weighed on an Ohaus balance at the USDA-ARS laboratory in Gaines-
ville, Florida to determine mean biomass. For beetle species that were not weighed,
biomass was assumed to be similar to beetles of the same size. Extrapolation was nec-
essary only with small, less common beetles.
Beetle biomass at all sites was summed over time, and the differences between pri-
mary, secondary, and clear-cut habitats were tested with a one-way ANOVA. I used
Scheffés test for multiple comparisons, and Students t-test to compare primary and
secondary growth at Caxiuanã (beetle biomass in the clear-cut at this site totaled only
0.006 grams, and was excluded from the analysis).
Beetles were categorized as those that buried almost no seeds, those that buried at
least 20% of small seeds, and those that buried at least 20% of both large and small
seeds. These groups were then compared for their proportion of total dung beetle bio-
mass at each site using one-way ANOVA.
Monkeys
To categorize primate primary seed dispersers, I censused monkey populations at
the three sites: 36 times in Rondônia and Ducke, and 27 times in Caxiuanã. Monkey
transects were stratified by the proportion of secondary and primary growth at each
site. Transects were walked by 2 people, and transect pace was about 1 km/hr. Monkey
species and number of individuals were recorded.
I used methods described in Chapman et al. (2000) to calculate monkey density,
using a 50% cut-off rule to select the sighting distance. Observer to animal distance,
as opposed to perpendicular distance was used, as quantitative comparisons suggest
Vulinec: Dung Beetles, Monkeys, and Conservation
233
perpendicular distance underestimates transect width for forest primates (Chapman
et al. 1988). Densities of groups were then calculated as the number of groups sighted
within the truncated sighting distance divided by the area sampled, that is, the
length of the transect times the truncated distance (Chapman et al. 2000). Densities
were calculated for groups per square kilometer and number of individuals per square
kilometer.
The proportion of monkeys that are seed predators as opposed to seed dispersers
was evaluated using a Chi-square contingency table test for differences among the
three sites.
R
ESULTS
Seed Burial
Some beetles, for example all species of
Euysternus
, bury almost no seeds. The
quality of other species as seed buriers depends on several factors, including seed bur-
ier size. Larger beetles bury more seeds than smaller beetles simply because they
bury more dung. Additionally, large species are capable of burying larger seeds (Table
1). Burrower guild beetles bury small seeds fairly well, while rollers are less capable.
Seeds over 10 mm are only buried by the largest burrowers (Figs. 1 and 2).
Biomass of Seed-Burying Beetles In Different Sites
Beetle biomass differed among sites (ANOVA, F = 7.58, P < 0.03); Rondônia had
nearly four times higher biomass than Reserva Ducke. The mean biomass in primary
forest was significantly higher than secondary forest at Rondônia and Caxiuanã, but
not at Reserva Ducke (Table 2). Biomass at all sites was highly significant between
both primary and secondary forest and clear-cuts (only two beetles were collected in
the clear-cut at Caxiuanã).
Biomass was significantly different among the three seed burial categories at
Reserva Ducke (ANOVA, F = 4.97, P < 0.02), and Rondônia (ANOVA, F = 5.79, P <
0.005), but was not significant at Caxiuanã. Biomass of small seed buriers was low at
Reserva Ducke, while beetles that buried large and small seeds dominated the bio-
mass (Fig. 3). At Caxiuana, beetles of all size categories were somewhat equal in bio-
mass, and at Rondônia, beetles that buried large and small seeds comprised the
largest amount of biomass, but other categories were also abundant.
Proportion of Seed Predating Monkeys at Each Site
Monkey densities varied significantly among the three sites (ANOVA, F = 4.5, P <
0.01). Total densities for all species at each site were 38.55 individuals per square kilo-
meter for Caxiuanã, 8.94 for Reserva Ducke, and 28.42 for Rondônia. Differences in
the proportions of seed predators versus seed dispersers in monkey abundance were
significant among the sites (
c
2
: Caxiuanã vs. Ducke = 44.7, p < 0.001; Caxiuanã vs.
Rondônia = 10.4, P < 0.005; Ducke vs. Rondônia = 101.0, P < 0.001; Fig. 4).
D
ISCUSSION
In rainforests, seedlings have a higher survival rate when not directly under the
parent tree (Howe et al. 1985; DeSteven and Putz 1984; Augspurger 1983). This sur-
vival is thought to occur because the seedling escapes from predators and pathogens
234
Florida Entomologist
83(3) September, 2000
of the parent (Howe & Smallwood 1982; Connell 1971; Janzen 1970), and because dis-
persal reduces competition for resources (Stiles 1989).
Trees have evolved strategies to disperse their offspring to other locations. Fruit
and the seeds within generally travel away from their parent inside animal guts.
Monkeys are considered by many authors to be high quality seed dispersers (Castro
1991; Estrada et al. 1991; Rowell & Mitchell 1991; Chapman 1989; Howe 1989; Gar-
ber 1986). However, some monkeys are better seed dispersers than others, for exam-
ple, some eat leaves or nectar in addition to fruit, some travel more, some defecate
seeds out singly, or may defecate them in a mass (Veracini 1996; Zhang & Wang 1995;
Castro 1991; Chapman 1989; Garber 1986). Most importantly, some monkeys, prima-
rily the sakis, are generally seed predators (Norconk 1998; Peres 1993; Van Roose-
malen et al. 1988). The proportion of seed predators in monkey communities varies
greatly at each locality. These findings may reflect a very different potential in differ-
ent areas for forest regeneration.
Secondary seed dispersal and burial by dung beetles may also have an impact on
rainforest regeneration (Feer 1999; Andresen 1998; Estrada et al. 1991). The highly
significant difference between beetle biomass at Rondônia and the other two sites
might have a number of causes. It could reflect the shorter history of disturbance, the
abundance of mammals, climatic factors, or vicariance. Nevertheless, the overall bio-
T
ABLE
1. S
OME
OF
THE
BEETLE
SPECIES
TESTED
FOR
SEED
BURIAL
CATEGORY
,
THE
AB-
BREVIATIONS
USED
IN
THE
FIGURES
,
SOME
BEHAVIORAL
CHARACTERISTICS
,
AND
MEAN
BIOMASS
. A
BB
=
ABBREVIATION
;
GMS
=
GRAMS
.
Species Abb. Type of dung
manipulation Activity
period Mean biomass
gms (SE)
Canthon aequinoctialis
Har. Ca Roller Nocturnal 0.130 (0.045)
Canthon triangularis
(Drury) Ct Roller Diurnal 0.038 (0.010)
Coprophanaeus lancifer
(L.) Cl Burrower Crepuscular 3.260 (1.021)
Dichotomius
nr.
batesi
Dbat Burrower Diurnal 0.073 (0.007)
Dichotomius boreus
(Oliv.) Dbor Burrower Nocturnal 0.452 (0.161)
Dichotomius lucasi
(Har.) Dluc Burrower Nocturnal 0.099 (0.020)
Dichotomius podalirius
(Fels.) Dpod Burrower Nocturnal 0.452 (0.161)
Eurysternus caribaeus
Herbst Ec Neither Nocturnal 0.102 (0.028)
Oxysternon conspicilla-
tum
(Web.) Oc Burrower Diurnal 0.798 (0.244)
Phanaeus cambeforti
Arnaud Pcam Burrower Diurnal 0.136 (0.042)
Phanaeus chalcomelas
(Perty) Pch Burrower Diurnal 0.146 (0.042)
Scybalocanthon
nr
.
pygidialis
Sp Roller Diurnal 0.027 (0.005)
Vulinec: Dung Beetles, Monkeys, and Conservation
235
Fig. 1. The total proportion of small seeds (< 5 mm) left on the soil surface by some
beetle species. See Table 1 for species abbreviations and characteristics.
Fig. 2. The total proportion of large seeds (> 10 mm) left on the soil surface by some
beetle species. See Table 1 for species abbreviations and characteristics.
236
Florida Entomologist
83(3) September, 2000
mass of beetles and the proportion of those that bury seeds may be highly important
to the local ecology. Reserva Ducke is dominated by beetles that bury both large and
small seeds. The proportion of the biomass that buries only small seeds is very low.
Because beetles that bury large seeds are mostly nocturnal (Vulinec 1999), the parti-
tioning of beetle biomass may have an effect on seeds that are deposited during the
day. Seeds deposited by monkeys in transit may not be buried immediately, and could
be left on the ground until discovered by rodents, ants, or weevils. It would be ex-
pected that at this site, seeds may suffer higher mortality from seed predation, first
by saki monkeys, and then by seed predators on the forest floor.
In regeneration of secondary growth areas, dung beetles may prove even more im-
portant than in primary forest. Primary seed dispersers, such as birds and monkeys
will enter secondary growth, especially if there are trees such as bananas and
Cecro-
pia
spp. (Holl 1999). Therefore, seeds from primary forest can get to these areas (Dun-
can & Chapman 1999). However, rodents are often more prevelant in secondary
T
ABLE
2. M
EAN
BEETLE
BIOMASS
(
SE
)
IN
EACH
OF
THREE
HABITAT
TYPES
AT
EACH
SITE
.
MEANS
SHARING
LETTER
IN
EACH
ROW
ARE
NOT
SIGNIFICANTLY
DIFFERENT
.
C
AXIUANÃ
(S
TUDENT
’
S
T-TEST, P < 0.001), * = ONLY THREE BEETLES CAUGHT;
DUCKE (SCHEFFES’ MULTIPLE COMPARISONS, P £ 0.003) AND RONDÔNIA
(SCHEFFES’ MULTIPLE COMPARISONS, P £ 0.002).
Site Primary forest Secondary growth Clear-cut
Caxiuanã 5.07 (2.65)a2.49 (1.66)b*
Ducke 9.85 (1.71)a7.03 (1.15)a0.41 (0.11)b
Rondônia 36.55 (4.16)a19.78 (3.10)b0.58 (1.10)c
Fig. 3. Total beetle biomass at each site stratified by three categories of seed burial
behavior.
Vulinec: Dung Beetles, Monkeys, and Conservation 237
growth, so predation may also be greater (Asquith 1997). It would be advantageous to
a seed to be buried quickly in these areas. Dung beetles are far more abundant in sec-
ondary growth than clear-cuts (Vulinec 1999; Estrada et al. 1998). Additionally, sec-
ondary growth has more similar microclimates and soil characteristics to primary
forest than pastureland, where soil compaction and low humidity may keep many
dung beetles out. Secondary growth has the potential to reforest relatively quickly
given the primary and secondary dispersers that enter it. Clear-cuts have much less
chance of rapid reforestation, and in some cases, no chance.
Beetles that roll dung, rather than burying it directly under the dung pat, domi-
nate clear-cuts (Vulinec 1999; Halffter et al. 1992). Rollers, despite relocating seeds
from the source, often do not bury brood balls deeply enough to protect the seeds
within from rodent predation. Additionally, the generally smaller size of these beetles
would make them less effective as processors of larger seeds, or a quantity of seeds.
This factor suggests that savanna adapted species would probably not contribute sig-
nificantly to forest regeneration in secondary growth (Vulinec 1999).
Beetles that frequent secondary forest are, like those in primary forest, more likely
to be good seed “planters”, due to beetle size, depth of burrowing activity, and abun-
dance (Vulinec 1999). Nevertheless, in two of the three sites, beetle biomass was sig-
nificantly greater in primary growth than secondary growth. Many beetle species are
very sensitive to changes in habitat, while other species, such as Dichotomius, are
more flexible in habitat preferences (Vulinec 1999). The factors that encourage high-
quality seed buriers to enter secondary forest should be investigated. Manipulation of
these factors could increase regeneration of primary forest from secondary growth ar-
eas. For example, beetles may respond to humidity when foraging or mate seeking.
Planting broad leafed trees (such as Cercropia) in abandoned cut areas may increase
ground level humidity and recruit more large dung beetles (and monkeys) from pri-
mary forest to these areas, resulting in quicker primary forest regeneration.
Fig. 4. Density of monkeys at each site and proportion of seed predators versus
seed dispersers.
238 Florida Entomologist 83(3) September, 2000
Amazon rainforest is disappearing at a distressing rate; in the Brazilian Amazon
2,554,000 ha of forest are cleared yearly, a number that does not include clearing due
to selective logging or destruction by fires (FAO 1999). Deforestation in the Neotropics
has profound effects on carbon cycling, the hydrological cycle, and soil and water qual-
ity (Salati 1985). For example, 50-75% of precipitation in the Amazon is returned to
the atmosphere in the form of water vapor through evaporation of the water retained
by leaves, and through transpiration of the plants (Salati 1985). Cutting the forest
can radically change the water cycle.
The majority of the clear-cutting in the Amazon is for cattle ranching, and the
greatest clearing is by large agribusiness corporations. According to Fearnside (1993),
beef productivity on Amazon soils is low, and is unsustainable. Available phosphorous
limits grass yields on oxisols and ultisols. Inedible weeds that are more adapted to the
poor soils quickly invade pastureland. Massive government programs that subsidize
pasture have claimed that pasture improves the soil, and is indefinitely sustainable.
However, further studies have shown that maintained pasture productivity is not pos-
sible without the addition of phosphorous fertilizer. But adding fertilizer will still not
solve the problem of pasture degradation. Soils become compacted through the expo-
sure to sun and the trampling of cattle. My own measurements of soil density in forest
and clear-cuts showed a 2 to 4 fold increase in relative density in clear-cuts, even with-
out cattle (Vulinec, unpub.).
In a recent study, Holl (1999) suggests that although regeneration of forest in pas-
tures is limited by colonization, establishment, growth, and survival, the major lim-
iting factor in seedling establishment is lack of seed availability. She suggests pasture
restoration to forest by planting native tree seedlings to increase canopy architecture,
installing bird perching structures, and planting rapidly growing shrubs that quickly
produce fruit and attract seed dispersers. I also suggest that there must be a nearby
refuge of protected species to provide the necessary colonizers, including plants, pol-
linators, and dispersers, and secondary dispersers such as dung beetles.
Logging is another large-scale use of tropical forests. Currently, decisions about
logging in the Amazon have no central planning or coordination. Without this plan-
ning, logging industries could easily log all of the forest in the state of Pará (Veríssimo
et al. 1998). Veríssimo et al. (1998) conclude that logging could be a sustainable indus-
try that would preserve diversity and indigenous rights and suggest several ways to
do this. Logging would have to be highly monitored, however. Nepsted et al. (1998b)
maintain that even selective logging diminishes forest cover, allows the drying of un-
derstory vegetation, and sets the stage for devastating fires as were seen in 1998.
Even one fire in an area significantly increases the chances of future fires. The more
fires in an area, the more brushy secondary growth and open canopies invite more
fires in a positive feedback loop (Nepstad et al. 1998a).
Perhaps most importantly, loss of tropical rainforest leads to loss of biodiversity.
There may be as many as 5-30 million species of plants and animals still undescribed,
and unknown, the vast majority in tropical forests (Erwin 1982). We have yet to un-
derstand the interrelationships among the flora and fauna living in these critical ar-
eas. What we don’t understand may do more than just prevent us from finding a cure
for cancer. The loss of pollinators and dispersers will affect uncounted species of
plants, many of potential economic and ecological importance. My research shows
how even seemingly insignificant organisms may have important roles in ecosystem
function. If dung beetles were gone, the buildup of feces, the increase in dung breeding
pathogens, the loss of some soil turnover, would become rapidly apparent (Vulinec
1999; Klein 1989). Predatory mites that hitch rides on dung beetles would disappear.
Potential antifungal and antibacterial chemicals may never be discovered. And very
importantly, seeds deposited in dung would remain on the surface vulnerable to ro-
Vulinec: Dung Beetles, Monkeys, and Conservation 239
dents, fungi, and granivorous insects. Conversely, if vertebrate seed dispersers disap-
peared, the 60% of tree species, and almost 100% of understory plants that depend on
vertebrate seed dispersal would also decline. Dung beetles would vanish with them.
ACKNOWLEDGMENTS
I thank the following organizations for their support of my research: The Fulbright
Commission for International Studies, The Charles A. and Anne Morrow Lindbergh
Foundation, the Florida Center for Systematic Entomology, the Dickinson Award for
Tropical Agriculture at the University of Florida, The University of Florida’s Women
in Agriculture Club, and the J. D. Turner Foundation.
In Brazil, I am grateful to O Conselho Nacional de Desenvolvimento Científico e
Tecnológico (CNPq), Instituto National de Pesquisas da Amazônia (INPA), and Museu
Paraense Emílio Goeldi (MPEG). I am especially thankful to Claudio R. V. da Fonseca
of INPA and Pedro L. B. Lisboa of the Museu Paranese Emilio Goeldi.
Special thanks are due David Almquist and Freida Ansoanuur for sorting insects,
Bruce Gill, Dave Edmonds, and Fernando Vaz de Mello for help with identifications. I
am indebted to Colin Chapman and John Sivinski for comments on this manuscript.
I also thank Coleman and Corey Kane for their assistance in Brazil and the States,
and Dave Mellow for everything.
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