Point-counterpoints on the conservation of big-leaf mahogany

28 Pages·1999·2.7 MB·English

by  Lugo, Ariel E

document
Historic, archived
Do assume
not content reflects current
scientific knowledge, policies, or practices.
1
sow
c-J-
United States
on
Department of Point-Counterpoints
Agriculture
Forest
the Conservation of
Service
Gen. Tech.
Report WO-64 Mahogany
Big-Leaf
March 1999
Lugo
Ariel E.
CP
CP
Coverphoto: A leafless, fruiting adultmahogany tree emerges
above the forestcanopyin south Para, Brazil. (Photo byJimmy
Grogan)
on
Facts
Mahogany
Big-Leaf
The complexity oftropical forests has long challenged throughout Central America, this scenario foresees
foresters' efforts to manage their use sustainably. The little probability of significant genetic erosion result-
applicability of temperate zone silvicultural systems ing from logging. It finds no evidence to support sig-
is still unproven under most tropical conditions. Nev- nificant losses to the shoot borer. Moreover, the
ertheless, a large fund of knowledge and experience existence of 150,000 hectares (ha) of plantations of
about their management has been acquired over more mahogany suggests the possibility of an early offset,
than a century. Such experience has been summa- in terms of products, for timber removal from natural
rized by Dawkins and Philip (1998) and Wadsworth forests.
(1997). There are guides that show how both utiliza-
tion of and protection of forest resources can be Dr. Ariel E. Lugo, ofthe International Institute ofTropi-
sustained. cal Forestry in Puerto Rico, has contributed to the de-
velopment of a scientifically based mahogany
Sustaining big-leaf mahogany, an outstanding tree of management model in several ways. His most recent
tropical forests, is of particular interest. The timber of contribution, which accompanies this fact sheet, is
this tree is almost unsurpassed in value for furniture Point-Counterpoints on the Conservation of Big-Leaf
and cabinet work. In the forest, this species is eco- Mahogany. This publication aims to "draw attention
logically resilient. Seed production is copious, even to research relevant to the evaluation of the conser-
at early age, outcrossing is common, germination is vation status of big-leaf mahogany and to clarify mis-
abundant, seedlings respond to light and grow well conceptions concerning the species and its place in
under a wide range of conditions, nutrient use is effi- tropical forests." Dr. Lugo addresses the following is-
cient, growth is rapid, lifespan is long, and ultimate sues in his paper:
crown development dominates the forest canopy. The
species is well adapted to forests opened by catastro- • Big-leaf mahogany is adapted to several life zones,
phes or silvicultural treatment. mainly in lowland dry or moist seasonal climates.
Its natural range is large, some 200 million ha, from
A current proposal to list the species under Appendix Mexico to Bolivia.
of the Convention on the International Trade in En-
II
dangered Species (CITES), requiring certification of a • Big-leaf mahogany forests are vulnerable and need
sustainable source of traded mahogany, is derived protection and sound management. The species is
from a worst-case scenario. Present or potential en- in no danger of extinction, but the stock of large
dangerment is laid to tropical deforestation, inad- trees has been reduced by utilization.
equate natural regeneration, genetic erosion arising
from fel ng the best trees, and losses due to the shoot • Natural big-leaf mahogany forests show a favor-
Ii
borer. able stem-diameter distribution, with trees of all
sizes and with immatures ready to assume domi-
Another equally supported scenario questions the nance, given time.
present and potential endangerment of the species.
This scenario notes that deforestation is not entirely • Big-leaf mahogany in the natural forest and in plan-
concentrated in mahogany forests and is less con- tations is a relatively fast-growing species. Ma-
vinced of reported "inadequacies" of natural regen- hogany increment, overall, may even equal the
eration. On the lack of evidence of genetic variation volume of international trade, thus sustaining total
in growth rates and in shoot-borer susceptibility standing volume.
There is no evidence that logging causes signifi- exist. It has been used for forest restoration on aban-
cant genetic erosion of this species. Evidence so doned agricultural areas and underplanted beneath
far available suggests that there is a high gene flow secondary forests that invade clearings.
among mahogany populations, but further research
on this point is desirable. • The volume of mahogany sold internationally each
year is only 1 percent of the standing volume. This
The mahogany shoot-borer (Hypsipyla grandella) indicates that the endangered status of mahogany
has been shown by recent experience to be a man- is a myth. In addition, growing concern with
ageable insect. Obviously no deterrent to the size sustainability has led progressive producers of for-
or quality ofthe big-leaf mahogany being harvested est products concerned with market share to ob-
from natural forests, it no longer prevents success- tain certification of sustainability.
ful, large-scale plantations in areas where the in-
sect exists. • Ninety-six percent of the tropical timber cut does
not enter into international trade, making futile the
Regeneration success with big-leaf mahogany de- attempts to reduce tropical deforestation and en-
pends not only on abundant seed and sufficient dangerment of tropical timber species by impos-
light for seedling growth, but also on advanced re- ing requirements that affect only international trade.
generation already in place during the harvest of
mature ones. Inventories indicate that in old-growth • Guarantee of a sustainable source of exported tim-
forests immature trees are usually present. ber is unattainable for concessionaires removing
timber from forests they do not own. Strict adher-
The high potential of big-leaf mahogany for regen- ence to this requirement would depress the value
eration may be set back by careless logging, but of export timber that does not qualify as sustain-
low-impact logging can protect the seedlings and able and would add incentive to convert the land
immature trees. The latter, however, may not open to some other use without even extracting the
the canopy enough to promote their growth. Silvi- timber.
cultural liberation treatment is generally needed.
• The decision to list big-leaf mahogany under Ap-
Active forest management is the best alternative pendix II of CITES is a matter of policy and not
for big-leaf mahogany conservation. Enough is solely a technical decision. This determination nev-
known to provide guidance to tropical countries if ertheless should rest on the scientific information
they decide to manage it. This has the companion currently available, including that presented in
advantage of preserving much of the biodiversity Dr. Lugo's paper.
that dominates forests where mahogany is a
component. Literature Cited
Deforestation does not necessarily rule out the pro- Dawkins, H.C., and M.S. Philip. 1 998. Tropical moist
duction of big-leaf mahogany. Deforestation by the forest silviculture and management: a history of suc-
Mayan culture led to greater than normal mahogany cess and failure. CAB International, New York, New
populations. York. 359
p.
Big-leaf mahogany has characteristics that predis- Wadsworth, F.H. 1 997. Forest production for tropical
pose it to success in plantations. Its silviculture is America. Agriculture Handbook 710. USDA Forest
well understood, and many examples of success Service, Washington, D.C. 563 p.
Point-Counterpoints on the
Conservation of Big-Leaf Mahogany
by Ariel E. Lugo
International Institute of Tropical Forestry
USDA
Forest Service
Abstract Endangered Species (CITES), Participants in the debate counterpoint approach to
transcends the natural bound- about the conservation of draw attention to the polarity
The objective of this publica- aries of the species range. mahogany represent a broad of that debate and to clarify
tion is to draw attention to The outcome of the big-leaf spectrum of society, both in the issues.
research relevant to the mahogany debate will affect terms of geography and in
evaluation of the conserva- the internationa—l trade of all their professional interests.
tion status of big-leaf timber species whether they The debate is global in terms Tropical Forests
mahogany and to clarify are endangered or not, or of geography and in that the
misconceptions concerning whether their origin is tropi- professional interest of par- Point: All tropical forests are
the species and its place in cal, temperate, or boreal. ticipants spans from that of rain forests.
tropical forests. Many of these Moreover, in reference to the general public to highly
Counterpoint: Most tropical
misconceptions have clouded public opinion, the big-leaf specialized scientists. While
the debate regarding the mahogany issue is framed there have been several syn- forests are seasonal and dry.
possible listing of big-leaf within the debate concerning theses regarding the conser- Tropical forests constitute
mahogany in Appendix II of the overall condition of tropi- vation of big-leaf mahogany about half of the world's
the Convention for the Inter- cal forests, their biodiversity, (Lamb 1966, Hartshorn 1992, forests (dividing 1.76 billion
national Trade of Endangered and the allowable level of MacLellan 1996, Bauer and hectares of tropical forests
Species (CITES). Available human intervention in natural Francis 1998, and Mayhew [fig. 1] by 3.44 billion hect-
data are used to address 14 ecosystems. Given the impor- and Newton 1998), many of ares of world forests [FAO
point-counterpoint issues tance of the big-leaf ma- the points of disagreement 1995] = 51 percent). Tropical
surrounding the controversy hogany issue, it is imperative continue unresolved because forests are diverse not only in
about the ecology and man- to consider the best scientific there has been no attempt to species composition but also
agement of big-leaf ma- information available so that sort available facts from opin- in the number of species
hogany. In addition, four policy formulation is ions or hypotheses. As a associations. There are more
critical questions regarding informed. result, progress is slow. The forested lifezones (sensu
the issues of genetic erosion debate is hindered by the Holdridge 1967) in the trop-
and conservation of genetic persistence of unsubstantiated ics than in the temperate and
variation of big-leaf ma- positions or the presentation boreal latitudes combined
hogany throughout its range of "facts" that are either un- (table 1 ). Because the low-
are examined. Worst-case tested hypotheses or points of land tropics have a narrow
scenarios of the big-leaf ma- view whose truthfulness rest temperature range, lowland
hogany situation in tropical on hidden or unspecified tropical forests are more
America are examined and assumptions. The resulting adequately classified accord-
science-based conservation confusion has negative con- ing to annual rainfall: 500 to
strategies are outlined. sequences to the formulation 1,000 millimeters for dry
of policy because policy- forests, 1,000 to 2,000 milli-
makers find themselves un- meters for moist forests, 2,000
Introduction able to differentiate opinion to 4,000 millimeters for wet
from scientific understanding. forests, and more than 4,000
The status of big-leaf ma- The objective of this report millimeters for rain forests
hogany, one of the most valu- is to draw attention to re- (Holdridge 1967). Most ofthe
able and best known tropical search relevant to the evalua- tropical forest lands are clas-
timbers, has been the subject tion of the ecology and sified as dry forests, followed
of global attention over the management of big-leaf ma- in area by moist forests (table
past decade. The importance hogany and to clarify miscon- 1 ). Wet and rain forests cover
and scope of the debate, Leaflessyoung adult tree in ceptions that have clouded the least area.
centered on the possible south Para, Brazil, with fruit the debate about this species Big-leaf mahogany is
listing of the species in Ap- capsules. (Photo byJimmy and the tropical forests to mostly a lowland dry forest
pendix II of the Convention Grogan) which it belongs. The discus- species, although it also
on the International Trade of sion is framed with a point- grows in moist forests and at
1
Point-Counterpoints on the Conservation of Big-Leaf Mahogany
of agricultural products are the national and global. Such
high. Most tropical deforesta- a focus allows better under-
2000
tion occurs to compensate for standing of the proximate
Africa
Asia the degradation of agricul- causes of deforestation.
1750
r~l LatinAmerica tural lands (Dale et al. 1993).
Total Forestry activities account for Point: Deforestation is
1500
u a small proportion of the total irreversible.
0) deforestation in the tropics
JcZ 1250 (Kaimowitz and Angelsen Counterpoint: Tropical forests
o 1998), which means that can be restored in deforested
areas.
1000 even total cessation of inter-
national trade in forest prod- Tropical deforestation is
C0O) 750 ucts would solve at best only not irreversible. In the ab-
a small proportion of the sence of further human activ-
500 VA deforestation problem. The ity, secondary forests develop
indirect effects of roads is in most areas previously
250 discussed below in the log- deforested and used for pur-
ging section. poses other than forests
Because the causal forces (Brown and Lugo 1990). The
1920 1970 1980 1990 1995 underlying deforestation are reforestation of abandoned
complex, it is impossible to pastures, agricultural fields,
Year
extrapolate pantropical or and even cities, such as those
even country-level deforesta- of the Maya, is a natural
tion rates to the habitat of a process mediated by animal
Figure 1. Estimates ofthe area oftropical forests. Sources of —
d1a9t7a4;are1:98109'20s'—sF—AZOo/nUNaEnPd S19p8a2r;ha1w9k9019—2F3A;O1917909'3sa—;Pearnsdson pleaarftimcaulhaorgaspneyc.ieIsn sfuaccth, casoubni-g- smeaemdmadilssp,ersaenrds instehcatts.is,Mobisrtds,
1995—FAO 1997. tries with the largest fraction of the Central American range
of big-leaf mahogany habitats of big-leaf mahogany was
are those with some of the deforested for a millennium
lowest rates of deforestation by the Maya (Lamb 1 966).
elevations of up to 1,400 America, a rise followed by a among range countries Mature secondary forests with
meters above sea level (Lamb decline in Africa, and a simi- (table 2). But such facts do large big-leaf mahogany trees
1966). Its large natural distri- lar pattern for the whole not help explain land-use now are found in the region.
bution (some 200 million region. Apparently the esti- trends within the range of Similarly, secondary for-
hectares) and growth in plan- mated area of tropical forests big-leaf mahogany. Specific ests now occur in the State of
tations span several lifezones, in 1 995 was either the same studies at the proper spatial Para, Brazil, where the con-
from tropical and subtropical as or higher than that esti- scales are needed to support struction of the transama-
dry, to tropical and subtropi- mated in the 1920's. The any conclusions about the zonian highway in the 1970's
cal moist, to wet forest. Big- uncertainty in these estimates relationship between the resulted in a deforestation
leaf mahogany does not, is high given the large area, status of big-leaf mahogany event that appeared in satel-
however, grow well in more its inaccessibility, and the and the rates of deforestation lite images as a "fishbone
humid lifezones, such as poor state of knowledge in the tropics. For this reason, pattern" with the main road
subtropical lower montane about the tropics. Kaimowitz and Angelsen running through the center
wet forests, nor in tropical or The rate of deforestation in (1998) recommended that and perpendicular deforested
subtropical rain forest the tropics is influenced by future research on deforesta- strips on both sides of the
lifezones. climatic condition, topogra- tion focus on the household road. These satellite images
phy, and social factors. In and regional scales instead of were used to justify proposing
general, rain and wet tropical
Deforestation forests experience lower
deforestation rates than moist
Point: Forestry activities and dry ones; flat lands are
cause deforestation in the deforested before steep lands; Table 1. Number of lifezones in the major geographic
tropics. and agriculturally based regions and climatic zones of the world (Lugo and
economies are more likeiy to Brown 1992) and area of tropical lands classified
Counterpoint: Forestry cause deforestation than according to lifezones (Brown and Lugo 1982). Area of
activities account for a small those based on fossil fuels. the tropical lifezones in parentheses, in million
proportion of tropical
Kaimowitz and Angelsen hectares.
deforestation.
(1998) reviewed 150 models
The rate of tropical defor- of tropical deforestation and Lifezone Geographic Reg on
estation has been estimated concluded that deforestation Category Tropics Temperate Boreal Total
to be between 0.6 percent per tends to increase when forests
year from 1981 to 1985, and are readily accessible, agri- Dry 33 (1,887) 16 3 52
0.8 percent per year from cultural and timber prices are Moist 11 (1,582) 7 2 20
1981 to 1990 (FAO 1993a). high (with agricultural prices Wet/rain 22 (642) 14 4 40
Estimates of the area oftropi- being a stronger determinant Total 66 (4,111) 37 9 112
cal forests since the 1920's than timber prices), rural Forested 33 16 3 52
(fig. 1) show a fairly constant wages are low, and opportu-
area for Asia and Latin nities for long-distance trade
2
Point-Counterpoints on the Conservation of Big-Leaf Mahogany
average and lower than that economic incentives for bet-
Table 2. Rate of deforestation (1 980 to 1 990) in of the United States and other ter management and conser-
countries where big-leaf mahogany grows naturally developed countries (fig. 3). vation of tropical forests
(FAO 1993a). Tropical forests contain (Browder et al. 1996).
more tree species per unit
area than any other forest
Country Deforestation (percent per year)
type in the world, but that Trade Situation
Belize 0.2 diversity of species has not
Bolivia 1 .2 been commercialized. Very Point: International trade of
Brazil* 0.6 few tropical species enter big-leaf mahogany causes
Colombia 0.7 local markets and fewer still deforestation; by reducing
Costa Kica 2.9 enter international markets. trade, tropical deforestation is
Ecuador 1l .O8 Yeom (1984) found that in abated.
Guatemala 1 .7 Malaysia, the most prominent Counterpoint: Deforestation
Honduras 2.1 timber producing country in in the range of big-leaf
MNeicxaircaog*ua 11..39 t3h,e00t0ropciocsm,mtohneretraereesapebcoiuets, cmoamhpolgeaxnysoicsicoaeucsoendombiyc
Panama 1.9 of which 677 are thought to
factors rather than by
Peru* 0.4 have commercial value. Of
international trade of the
Venezuela 1.2 these, 408 are actually used
species; reduction of trade
commercially. In Asia and
*Countries that together comprise 90 percent of the South and Central America, through nonmarket restric-
forest area containing big-leaf mahogany. fewer than 15 species ac- tions may, in fact, exacerbate
deforestation by devaluing
count for most of the lumber
forests.
trade.
The volume of tropical The known trade of big-
woods that enters the domes- leaf mahogany between 1850
the listing of big-leaf ma- Counterpoint: Most tropical tic and international markets and 1996 oscillated between
hogany in CITES (Amendment countries are net wood is a small fraction of the 70,000 and 140,000 cubic
to Appendix II, Tenth Meeting importers, and most of their standing wood volume in the meters per year, with occa-
of the Conference of the wood production is for forest (fig. 4). Species with sional peaks and valleys
Parties, Harare, Zimbabwe, fuelwood and charcoal for market potential but which beyond this range (for ex-
1997), based on the argument local consumption; exports of are not recognized by mar- ample, a 320,500-cubic-
that such deforestation was wood products from the kets are designated as "lesser meter peak in 1987) (fig. 5).
somehow related to the inter- neotropics are not significant known species." Many argue Importation to the United
national trade of the species. and do not compete with U.S. that for tropical forestry con- States between the 191 0's
Today, the landscape has products. servation to be effective, and 1996 ranged from 30,000
fcihsahnbgoende,paanttdertnheisdecfoovreersetded Wood is of critical impor- tnheeesdetloesbseerckonmmoewrncisapleciizeesd tyoear3.20T,h5is00lecvuebliocfmtertaedresdopeers
tance to tropical countries,
by vigorous secondary forests (Yeom 1984, Lugo 1987, not show a significant in-
particularly fuelwood and
in those areas abandoned by Gullison and Hardner 1993). creasing trend. In fact, im-
charcoal used for heating and
humans (Tucker et al. 1 998, cooking in regions where The use of lesser known spe- ports in the early 1950's were
Moran and Brondizio 1998). cies could relieve pressure on similar to the average of the
fossil fuels are either unavail-
Moran et al. (1996) found able or too expensive. Wood the few commercial species 1 990's. Imports to the United
that the rate of establishment now recognized and provide Sates are mostly from South
of secondary forests along the energy accounts for 58, 1 7,
and 8 percent of the total
transamazonian highway was
energy consumption in the
twice as high as the current
African, Asian, and American
rate of deforestation. Big-leaf
tropics, respectively (Masson
mahogany benefits from the
regeneration and spread of 1 983). Because of this need,
the tropics as a whole are a
secondary forests because it net importer of timber and
thrives in open areas, in sec-
have a fuelwood deficit (Lyke
ondary forests, or at the inter-
and Brooks 1995). The trop-
face between abandoned
ics are responsible for a small
pastures and secondary for-
fraction of the world's indus-
ests (Gerhardt 1994, 1996).
trial roundwood production,
but they produce the largest
amount of fuelwood and
TropicalTimbers
charcoal in the world (fig. 2).
However, even when
Point: Tropical countries
fuelwood consumption per
produce mostly wood
products for local consump- capita is included in the total,
the annual consumption of
tion and for export markets, wood by developing coun-
where they compete with Recentlygerminatedseedling in closedforest with simple leaves.
U.S. timber production. tries is lower than the world (Photo byJimmy Grogan)
3
Point-Counterpoints on the Conservation of Big-Leaf Mahogany
1400
IFuelwood
Developedcountries
IIndustrialroundwood
Developingcountries
§ 600 J
World
I
400
200
0.0 0.5 1.0 1.5 2.5
Temperate Boreal Tropical
Consumptionpercapita(m3)
Figure 2. Annual worldproduction ofindustrial roundwood
and fuelwood by latitudinal region (Lyke and Brooks 1995). Figure 3. Wood consumption by region ofthe world (Lyke and
Brooks 1995).
America. Mahogany exports al. 1 995). The volume of big-
from Central America in the leaf mahogany wood in inter-
1 990's were about 10 percent national trade is less than 1
of the total mahogany imports percent of estimated big-leaf
to the United States (fig. 6). mahogany stocks (assume a VolumeGrowth Grossvolumeingrowingstock
Trade exports from Para, trade of 320,500 cubic meters 1 to 8 m3/yr 232
Brazil, show a recent decline [highest value in fig. 5] di- Volumeactuallycommercialized ProductionofSawlousandVeneer
associated with internal con- vided by stocks of about 35 =
50.9 0.06m3ha1 yf1
trol measures (fig. 7). million cubic meters [Figue-
The United States im- roa Colon 1994] = 0.92 per- TROPICAL AMERICA
ported 4 percent of all tropi- cent of stocks in trade). This
cal timber products traded in volume is so small that the VolumeGrowth^ Grossvolumeingrowingstock
1989 (Smith et al. 1995). The global demand could be
most important tropical tim- satisfied with 70,000 hectares 1 to8m3/yr 352
ber species used commer- of slow-growing plantations Volumeactuallycommercialized ProductionofSawlogsand Veneer
2 »
cially that year by the United (box 1). Moreover, the extrac- 72.8 0.10m3ha"1 yr"1
States was big-leaf mahogany tion of big-leaf mahogany
TROPICAL AFRICA
(Smith et al. 1995). Of the causes very little disturbance
importation of tropical timber to forests (see below).
products to the United States Big-leaf mahogany habitat VolumeGrowth^ Grossvolumeingrowingstock
in 1993, big-leaf mahogany has been reduced in large
accounted for 57 and 59 sectors of its range for reasons 1 to8m3/yr 308
percent by volume and value, other than forestry activities. Volumeactuallycommercialized ProductionofSawlog-sandVeneer
respectively. Big-leaf ma- Land-use change in the trop- 88.2 i 0.39m3ha1 yr1
hogany wood is imported to ics responds to economic,
TROPICAL ASIA
the United States in two grade political, cultural, and other
levels for various end-uses by factors that are weakly influ-
industries that include furni- enced by international trade VolumeGrowth^ Grossvolumeingrowingstock
tmuarneufmaacntuufraecrtsu,refrosu,ndlrevyelindus- oprartthiecuelfafrecstpsecoifeslo(ggKianigmoowfitz 1 to8m3/yr 269
tries, door manufacturers, and and Angelsen 1998). In the Volumeactuallycommercialized ProductionofSawlog£sand Veneer »
architectural manufacturers mahogany debate, it is often 63.5 0.14 m3ha"1 yr"1
(Smith et al. 1995). pointed out that the loss of ALL TROPICS
International trade is not a habitat for big-leaf mahogany
major factor in the deforesta- is analogous to the loss of
tion process in Central and habitat that occurred in the
South America because the Caribbean for small-leaf ma-
amount of wood involved is hogany (Amendment to Ap- Figure 4. Gross volume in growing stock and volume actually
so small that its effects at the pendix II, Tenth Meeting of commercialized (cubic meters per year), and rate ofvolume
local scale are not significant. the Conference of the Parties, growth andproduction ofsawlogs and veneer (cubic meters
The total global trade in tropi- Harare, Zimbabwe, 1997). per hectare per year) between 1976 and 1979, in productive
cal timber products represents However, the socioeconomic, closed tropical forests (FAO/UNEP 1982). Data are for overbark
only 4 percent ofthe volume ecological, and geographic volume oftrees greater than 10 centimeters in diameter at
oftropical forest cut (Smith et conditions that led to the breast height.
4