THE ENVIRONMENTAL IMPACT OF ILLICIT NARCOTICS CULTIVATION IN SELECTED FOREST REGIONS OF LATIN AMERICA AND THE CARRIBEAN

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP98-00500R000200180003-8
• Release Decision: RIFPUB
• Original Classification: K
• Document Page Count: 16
• Document Creation Date: December 22, 2016
• Document Release Date: June 1, 2012
• Sequence Number: 3
• Publication Date: July 29, 1987
• Content Type: REPORT

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THE ENVIRONMENTAL IMPACT
OF ILLICIT NARCOTICS CULTIVATION
IN SELECTED FOREST REGIONS OF
LATIN AMERICA AND THE CARRIBEAN
JULY 29, 1987
EARTH SATELLITE CORPORATION (EarthSat)
7222 47th Street
Chevy Chase, Maryland 20815
[phone]
Telex: 248618 ESCO UR Telecopier: [phone]
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1.0 INTRODUCTION
It has been estimated that each year 11.3 million hectares of tropical
forest are cleared and converted for other land uses. Where land can
support sustainable agriculture, deforestation may be beneficial. But most
of the tropics' remaining forest land cannot sustain continuous farming or
grazing using current practices and is soon abandoned. This abandoned land
has lost much of its inherent productivity - a loss tropical nations and
the world can ill afford.
The loss of forest land has a range of consequences; degradation of
site productivity, decreases in water quality, increased erosion and
subsequent siltation, and a loss of biological diversity in both flora and
fauna. Most narcotic crop cultivation takes place in the tropical
latitudes. This illicit cultivation is now being recognized as a
particularly deleterious aspect of tropical deforestation. Narcotic crop
cultivators are usually new occupants to.a region and less knowledgeable
and concerned with local environments and suitable farming systems. Unlike
many native populations they cultivate the same plots until the soil is
exhausted.
The inherent nature of most illicit cultivation places it outside
national planned development and control. Often as the illicit cultivators
move from an exhausted site they select new areas removed from settlements
and legitimate agriculture. This process exacerbates the impacts to the
ecosystem, producing a series of degraded sites which have lost the ability
to maintain productivity. The effects of degraded productivity are
manifested throughout the surrounding area. Generally, tropical soils have
low native fertility and the ecosystem these soils support are delicately
balanced through the process of nutrient cycling. The disruption of this
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cycle can be studied and its effects measured, providing an understanding
of the nutrient cycling process and the impacts of tropical forest
clearfelling.
The following pages discuss the mechanisms controlling nutrient
cycling, nutrient retention following disturbance, and a methodology to
assess the impacts of clearfelling tropical forests for narcotic crop
cultivation on site nutrient dynamics. While there are many potentially
adverse impacts associated with clearfelling tropical forests for all
agricultural purposes, degradation of site productivity is clearly of most
concern. If site productivity is permanently degraded, all other adverse
impacts are also permanent, such as loss of species diversity and
degradation of water quality and soil properties.. More importantly,
permanent degradation of site productivity directly equates with loss of
agricultural and forest resource potential. Matson et al. (1987) citing
previous studies, estimated that 20-25x109 Kg of nitrogen are lost annually
from the 20-25x106 ha cleared for shifting cultivation. A demonstrated
loss of potential agricultural and forestry resources provides a. most
convincing argument for host governments. For these reasons nutrient
cycling and productivity aspects of ecosystem functioning are stressed here
rather than other ecosystem aspects.
The proposed methodology is designed to demonstrate loss of site
productivity through the monitoring of nutrient stocks along a temporal
sequence of disturbance history. Remotely sensed data are proposed as. the
tool necessary to identify the temporal sequence and, therefore, the
appropriate sampling sites. In addition, remotely sensed data
(specifically, Landsat TM) will be used to generate a spectrally classified
vegetation cover type data base. The classification will identify
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permanently degraded sites, which will also provide an indication of loss
of species, diversity.
2.0 BACKGROUND AND PROBLEM STATEMBNr
The first quantified, published findings concerning the environmental
impacts of deforestation were conducted in the White Mountains of New
Hampshire at Hubbard Brook (Likens et al. 1970). Selected sections of the
watershed were clearcut and the remaining cut vegetation was sprayed with
herbicide to prevent regrowth. Nutrient export from the cut site increased
eighty-fold in some cases as compared to the uncut (control) areas,
including increased export of potassium (K), calcium (Ca), sodium (Na) and
magnesium (Mg). In addition to nutrient export, which decreases site
productivity, increased soil erosion (partly responsible for nutrient loss)
and increased stream temperature were observed. Increased stream
temperatures have reduced dissolved oxygen content Sand result in unsuitable
habitat for some aquatic species. For example, stream temperatures above
68? F (20? C), are no longer suitable for trout habitat.
The Hubbard Brook findings stimulated many subsequent investigations
concerning nutrient cycling in environments throughout the United States
and other ecosystems of the world, with nitrogen (N) cycling being the
primary focus. Nitrogen is frequently a limiting nutrient, at least in
temperate ecosystems, and nitrogen losses have increased more than- any
other element in most reported studies (Vitousek and Melillo 1979).
Briefly, when an area is deforested, plant nitrogen uptake is eliminated
and nitrification (conversion of NH+ to NO. by microbial populations)
increases as a result of increased forest floor temperatures (from removal
of tree canopy). The excess microbial produced nitrate-N (NO3-N) is lost
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through leaching and soil erosion. Moreover, denitrification (NO
conversion to N2 and N20 through microbial respiration) is increased as a
result of increased microbial. populations (increased temperature) and
reduced competition with roots.
The numerous studies conducted in the United States subsequent to the
Hubbard Brook study all reported comparatively lower levels of nitrogen
loss on disturbed forest sites. Corbett et al. (1978) examining the
results of clearcutting investigations throughout the United States, found
that nutrient loss increased with increasing latitude, and also that stream
water temperature and sediment load decreased with increasing latitude. An
often cited criticism of the Hubbard Brook investigation was that soil
organic content (forest litter .layer) was comparatively high due to slow
decomposition in this temperature limited environment. Moreover, Hubbard
Brook receives considerable annual input from weathering of parent
material, which is not typical of all environments - especially deeply
weathered tropical laterites and infertile, well drained sandy soils.
Apparently, environmental differences among sites are important in
controlling the magnitude of nutrient loss following deforestation.
Vitousek and Melillo (1979) have suggested seven mechanisms of nitrogen
retention following clearfelling; several of these, such as anion
adsorption, immobilization, and denitrification, may be especially
important in the tropics.
Cycling of nutrient stocks is often cited as one of the primary
distinctions between temperate and perhumid (monthly precipitation values
of at least 200 mm each month, with no dry season) tropical forests, with
perhumid tropical forests characterized as being "tight" (Vitousek 1984).
In other words, nutrients lost from the biomass are not lost from the
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ecosystem, but quickly reabsorped after decomposition. The most common
evidence of this efficient nutrient cycling pattern is the lack of
anion/cation concentration within the stream water of such ecosystems
(Walter 1979). Conversely, temperate ecosystems are characterized as being
open, a considerable part of-the nutrient stock contained in the soil and
litter layer. Thick litter layers are common to forest floors of temperate
ecosystems. / `J r 1nS 21 !/Gi y /l ~G~ ~i'~~" /~~ u~hri~~~
The efficient nutrient cycling characteristic of perhumid tropical
forests appears to be a response to nutrient deficient soils (laterites)
common to this environment. Year-round high temperatures and abundant
rainfall afford rapid decomposition of litter and intensified leaching of
nutrients to lower soil profiles. Thus, while cold temperatures and/or
lack of precipitation in subtropical, temperate and alpine environments
limit productivity, perhumid tropical ecosystems are composed of species
that have adapted strategies to. increase productivity despite nutrient
limitations.
High root:shoot ratios and concentrations of fine roots at the soil
surface appear to be the primary mechanisms which enable quick reabsorption
of nutrients once they are introduced to the soil through litter fall.
In the upper Rio Negro region of the Amazon Basin thick mats of roots in
the upper soil surface layer (2 to 15 cm) were documented (Stark and Jordan
1978, Jordan 1985), which supports the assumption of an efficient
reabsorption strategy. Another mechanism, increased carbon fixation per
unit nutrient, has also been investigated, but.empirical evidence gathered
at one site does not support this theory (Vitousek 1984).
The general infertility of perhumid tropical forest soils stimulated
the initial concern over adverse environmental impacts resulting from
-{s 0 v
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deforestation, largely slash and burn agriculture. Removal of standing
vegetation and burning the resultant slash was thought to provide a flush
of nutrients which would not be able to be retained on site and, therefore,
would be permanently lost. This appeared to gain support from the
continual declining productivity and eventual abandonment of the site.
usually within three years.
Recent studies suggest other explanations to account for this quick
decline in crop productivity. It appears that agricultural crops cannot
make available the total nutrient stock. At a San Carlos, Venezuela site,
caS S~V~.
Manihot esculenta, the principal crop species, was found to have a
shoot : root ratio of 0.06. However, the average shoot : root ratio of
successional species was 0.23 (Jordan 1985). It appears that crop
productivity declines because of an inability to utilize potentially
available nutrients, while successional vegetation is able to incorporate
these nutrients and quickly restore the site's nutrient status to its
original state. Anion adsorption to clays deep in the soil profile
(previously mentioned) appears to be an important mechanism. of nitrogen
retention which the greater root mass of successional species is able to
.access.
The disturbed site, however,"must be allowed sufficient time to
recover if long-term site productivity is to be maintained. The nature of
the disturbance seems to be the critical factor which determines future
site productivity. Slash and burn agriculture has been classified as a
disturbance of moderate intensity and short duration (Jordan 1985) and does
not appear to permanently degrade site productivity. However, shortening
the duration of the fallow (successional) period eventually results in a
nutrient stock which is depleted beyond its ability to recover. According
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to Walter (1979). after a series of exposures to shifting cultivation the
soil can only support Pteridium spp. (tree ferns) or Gleichenia spp. and
continued burning allows the domination of alang-alang, Imperata
cylindrica. (Reference to Imperata cylindrica indicates observations were
made in Africa; Imperata brasiliensis is the tropical America
counterpart.)
In a study at Gran Pajonal, Peru (Scott 1978). replicating return to
agricultural through burning, it was estimated that greater than 1200 years
would be required for complete regeneration in the continually disturbed
site (Jordan 1985). The vegetation expressed at frequently burned sites is
commonly tropical grasses, which are-better competitors under fire stress.
This process of savannazation (conversion of forest to tropical grasslands)
is widespread in Africa's seasonal evergreen and semi-deciduous tropical
forests (Nye and Greenland 1964). Figure 1 provides an illustration of the
impact of a too frequent disturbance cycle on site productivity.
This degradation in tropical America has been less, presumably a
result of different land use practices, less population pressure and
probably subtle but important climatic differences. The demand for
narcotic crop products, though, can plausibly replicate the scenario
evidenced in Africa. It is EarthSat's hypothesis that narcotic crop
cultivation, as a result of its continually increasing demand and need to
be free from detection, will result in a disturbance cycle that threatens
long term site productivity.
As one progesses toward the margins of the tropics. away from perhumid
regions, adverse impacts of forest clearfelling may be enhanced by climatic
limitations on productivity. Productivity (rate of biomass accumulation)
decreases poleward from perhumid regions to seasonal, wet/dry (and montane)
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^VA
?1
0`
0 10 20 30 40 50 60 70 80 90 100110 120130
Figure 1: Fluctuation of humus carbon in the soil. Line A represents a
two year crop cycle with a twelve year fallow cycle. Line B represents a
two year crop cycle with a four year fallow cycle. Patterns of nitrogen
decrease should follow carbon patterns (Jordan 1985). Original graph
prepared from theoretical calculations by Nye and Greenland (1960), with
this figure reproduced from Jordan (1985, p. 121).
tropical forests, as a result of the introduction of one or more dry
periods and a general decline in annual precipiation. As productivity
decreases, nitrogen incorporation into the biomass per unit time decreases
and, therefore, the length of time required to return the nutrient stock to
pre-disturbance levels is greater. Also, as the length of the dry season
increases, the potential for fire is increased. Fire, which can be viewed
as a rapid mineralization of nutrients, favors domination of grasses at the
expense of woody vegetation. Grass cover prevents germination of woody
species and grasses are better adapted to regeneration following fire,
since their underground rhizomes are not destroyed (Jordan 1985). Assuming
this scenario to be correct, the potential for permanent site productivity
degradation in tropical wet/dry environments is greater than humid tropical
environments, since a longer recovery or successional period (in terms of
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nutrient stock) is necessary, and the threat of fire arresting succession
is increased.
Transecting an altitudinal gradient in the tropics also evidences
change in ecosystem functioning and nutrient dynamics. As altitude
increases, tree heights decline, temperatures decline and permanent cloud
forests eventually develop. Decreasing temperatures limit microbial
activity, likely causing nitrogen deficiencies. Alexandar and Pitchott
(1979), studying carbon:nitrogen ratios along an altitudinal gradient in
Colombia, found ratios to increase from less than 10 to greater than 15 as
altitude increased from 600m to 3700m; high C:N ratios inhibit plant
nitrogen uptake (Pritchett 1979). Tanner (1977) also found nutrients to be
limiting in four distinct Jamaican montane forests. Decomposition rates
were also less in the Jamaican montane forests than in lowland tropical
rain forests, a result, in part, of lower temperatures (Tanner 1981).
Tanner further suggested that'reabsorption of nutrients prior to leaf
abscission is important in the Jamaican montane forests studied.
Clearfelling and burning would destroy this nutrient conservation
mechanism.
In summary, investigations, to -date, indicate that forest ecosystems
in tropical environments are able to recover from clearfelling if
sufficient time is allowed for regeneration, which is necessary to restore
the nutrient stock. However, . continual return to the same site at short
intervals results in site nutrient loss which can take over one thousand
years to restore. Futhermore as one moves into tropical environments
experiencing a dry season or temperature limiting, high altitude tropical
environments, lower productivity and the increased threat of fire will
likely cause an increase in the length of the successional period necessary
-9-
51,7 t//h
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to restore the site to its original productive state.
3.0 I?THODOLOGY
The methodology proposed is designed around the collection of field
data that supports the calculations of Figure 1. using watersheds or a
complex of watersheds as the unit of investigation. The selection of
watersheds, therefore, should be implemented according to the watershed's
ability to replicate a chronic (shortened, quick return fallow period)
pv ti /
disturbance history reflected in line B of Figure 1. Z~,~'~~,
~/ ~i57v ~Or;~ q !!'
Remotely sensed data, in conjunction with client supplied information,
is proposed as the mechanism necessary for-identification of areas
appropriate for investigation. Landsat MSS and any available photographic
data sources will be used to identify areas with chronic disturbance ?1
V '",/t
cycles; Landsat MSS data provides a fifteen year chronosequence. The al
approach implemented by EarthSat for the Jamaica change detection study
will be used to identify watersheds exhibiting a chronic disturbance cycle.
Imagery should be acquired at a minimum o three year intervals for this
analysis. qh7' y?.4
Within the watersheds identified as appropriate for field sampling
(chronic disturbance cycle), sampling units (cultivated areas) will then be
identified according to the number of disturbances experienced during the
fifteen year period. Figure 1 suggests that a portion of these sample
units should have experienced three cultivation cycles within the fifteen
year temporal sequence to adequately reconstruct Figure 1 from empirical
data.
Field sampling will be composed of foliar nutrient content, soil
organic matter nutrient content and streamwater nutrient content analysis.
-10-
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Nutrient concentration analysis will be restricted to nitrogen (N) and
phosphorus (P), since these nutrients are most often limiting
(productivity), with phosphorus especially critical in tropical ecosystems
(Jordan 1985, Vitousek 1982). As illustrated in Figure 2, leaf production
is a feature distinguishing tropical forest ecosystems from other forest
environments (Jordan 1985). Coupling this feature with the "tight" or
efficient nutrient cycling common in tropical wet forest ecosystems,
provides one with the reasonable assumption that foliar nutrient content
(concentration) is an adequate estimate of total biomass nutrient content.
High atitude Temperate Subtropical Tropical
North South
odd
s.d.
leaves
Figure 2: Average and standard deviations of wood and leaf production from
mesic hardwood forest ecosystems of various latitudes. Data values are
originally published by Jordan (1983). Figure reproduced from Jordan
(1985, p. 9).
Combining foliar nutrient concentration estimates with soil organic
matter nutrient content will provide an index of the total nutrients (N,P)
available to an ecosystem.. In fact, Vitousek (1982) suggests that litter
dry mass/nutrient ratios (oven dried weight of total litter sample per
weight of nutrients in sample) provide a good index of nutrient economy
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within the unit sampled. Combinations of foliar and organic matter
nutrient concentrations will index total nutrient availability of the site
and provide insight into nutrient cycling within the site.
A third necessary estimate is stream nutrient concentration, to
provide an estimate of site nutrient export. The three estimates, in
total, will provide an adequate, time efficient estimate of nutrient
cycling and afford comparison of nutrient cycling mechanisms across an
environmental continuum. Furthermore, measurement of stream nutrient
concentration will provide a reasonable assessment of water quality..
Phosphoruseutrophication is a frequently evidenced problem affecting water
resources. The algal blooms of Lake Okeechobee (Florida) are 's most recent
and well publicized example. Schindler (1974) has experimentally
demonstrated phosphorus eutrophication in small Canadian lakes.
It is hoped that sampling of undisturbed situations can be eliminated
through compilation of related, previously published data. Vitousek (1984)
has published in tabular form productivity/nutrient cycling data from other
investigations conducted throughout the tropics. If this data can be
further supplemented, field sampling of undisturbed situations may be-able
to be eliminated.
Upon completion of the field sampling, -Earthsat will produce a
classifiaction of vegetation cover types for the areas field sampled using
1987 Landsat TM data. As indicated in Section 2.0, areas "permanently"
degraded can often be identified by the presence of particular species
associations -- tree ferns and grasses. Pteridium spp. and Imperata spp. vv~i( T/~l
respectively. A classification of vegetation cover types reflecting
disturbance patterns will provide a product identifying the spatial impact
of repeated forest clearfelling and provide a "map" identifying areas of-
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permanently degraded site productivity.
4.0 PROJECT PERSONNEL
The following resumes represent the type of interdisciplinary project
team EarthSat would expect to utilize in implementing the described
methodology. This type of environmental impact study requires expertise in
a range of both investigative and practical disciplines.
are:
Candidate members
'
Dr.
Dr.
Dr.
Charles Sheffield -
Carl Jordan -
Vernon Meetenmeyer -
James Durana -
Project Officer
Chief Scientist, Project Design
Project Advisor
Environmental Impacts/Assessments
Mr.
James Wickham -
Tropical Ecosystems
Mr.
Douglas Pool -
Tropical Agronomy
SI`'?)
Nancy Anderson -
Environmental Analysis
. Dennis Hlavka -
Agro-meteorology
Kim Freed -
Soils/Field Research
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Alexander, E.B. and`Pichott, J. 1979. Soil organic matter in relation to
altitude in equatorial Columbia. Turrialba 29: 183-188.
Corbett, E.S., Lynch, J.A. and Sopper. WE. 1978 Timber harvesting
practices and water quality in the eastern United States. Journal of
Forestry 76(8): 484-488..
Jordan, C.F. 1983. Productivity of tropical rain forest ecosystems and
the implications of their use as future wood and energy resources.
Pages 117-136, in Golley, F.B. (Ed..) Tropical Rain Forest Ecosystems:
Structure and Function, Vol 14A, Ecosystems of the World. Elsevier,
Amsterdam, The Netherlands.
Jordan, C.F. 1985. Nutrient Cycling in Tropical Forest Ecosystems:
Principles and Their Application in Management and Conservation.
John Wiley & Sons, Chichester, Great Britain. 190pp.
Likens, G.E., Bormann, F.H., Johnson, N.M, Fisher, D.W. and Pierce, R.S.
1970. Effects of forest cutting and herbicide treatment on nutrient
budgets in athe Hubbard Brook Experimental Forest, New Hampshire.
Ecological Monographs 40(1) 23-47.
Matson, P.A., V it ousek, P.M., Ewel, J.J., Marrazino, M.J. and Robertson.
P.G. 1987. Nitrogen transformations following tropical forest felling
and burning on a volcanic soil. Ecology 68(3): 491-502.
Nye, P.H. and Greenland, D.J. 1960. The soil under shifting cultivation.
Technical Communication No. 51 of the Commonwealth Bureau of Soils,
Harpenden, Commonwealth Agricultural Bureau, Farnham Royal. England.
Nye, P.H. and Greenland, D.J. 1964. Changes in the soil after clearing
tropical forest. Plant and Soil 21: 101-112.
Pritchett, W.L. 1979. Properties and Management of Forest Soils. John
Wiley & Sons, New York, 500pp.
Schindler, D.W. 1974. 'Eutrophication and recovery in experimental lakes:
implications for lake management. Science. 189: 897-899.
Scott, G.A.J. 1.978. Grassland development in the Gran Pajonal of eastern
Peru. Ph.D. dissertation, Department of Geography. University of
Hawaii.
Stark, N. M. and Jordan, C.F. 1978. Nutrient retention. by the root mat of
an Amazonian rain forest. Ecology 59: 434-437.
Tanner, E.V.J. 1977. Four montane rain forests of Jamaica: a
quantitative characterization of the floristics, the soils, and the
foliar mineral levels and a discussion of the interrelations. Journal
of Ecology. 65: 883-918.
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Tanner, E.V.J. 1981. The decomposition of leaf litter in Jamaican montane
rain forests. Journal of Ecology. 69:' 263-275.
Vitousek, P.M. 1982. Nutrient cycling and nutrient use efficiency.
American Naturalist. 119: 553-572.
Vitousek, P.M. 1984. Litterfall, nutrient cycling and nutrient limitation
in tropical forest. Ecology. 65: 285-298.
Vitousek, P.M. and Melillo, J.M. 1979. Nitrate losses from disturbed
forests: patterns and mechanisms. Forest Science. 25(4): 605-619.
Walter, H. 1979. Vegetation of the Earth and Ecological Systems of the
Geo-biosphere. 2nd. Ed. Springer-Verlag, New York, 274pp.
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