Tradeoffs Between Global Environmental Benefits,
Agricultural Sustainability and Adoption Criteria
“Best bet” Land-use Systems
Country reports
Alternatives to Slash-and-Burn in Cameroon
Unique id: IDAOKEXB
Source file: D:\Projects\ASB\ASB Country and Thematic
reports\Cameroom Final Report\Final Report&Synthesis of
PhaseII-Cameroon.xml
Authors: J. Kotto-Same, A. Moukam, R. Njomgang, T.
Tiki-Manga, J. Tonye, C. Diaw, J. Gockowski, S. Hauser, S. Weise, D. Nwaga, L.
Zapfack, C. Palm, P. Woomer, , Andy Gillison, D. Bignell, J. Tondoh
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Tradeoffs Within Land Use Systems
In order to compare tradeoffs across the various columns of
the matrix, it was first necessary to come up with summary indicators for
greenhouse gas emissions, above- and below-ground biodiversity, soil structure,
nutrient balance, crop protection, institutional requirements, food security,
and labor requirements. For each of
these, several indicators were developed and are summarized in “submatrices” of
the “meta-matrix” (tradeoff matrix Table 21).
Only for carbon stocks and profitability were single valued measures
available for comparing the socio-economic and environmental properties of
these land-use systems over time (i.e. time-averaged carbon stocks per hectare
and discounted net present value).
Although a single value indicator of biodiversity is presented in the
tradeoff matrix, it only represents the maximum biodiversity attained over the
course of the land use (i.e., in the long fallow intercrop, the measure was
taken in a 15-year-old bush fallow, which differed considerably from the
measure during the cropping phase).
The overall net impact on Global Environmental Benefits
(GEBs) is a function of the land conversion process--each system assumes some
type of change in land use patterns at start up. For the intercrop-fallow rotational systems
(#1 and #2), this involves an increase in the number of fallow-crop cycles
(from n to n+1) and, if population pressure is
increasing, a decrease in the fallow period over time (i.e. an increase in the
“Ruthenberg index” of cropping intensity).
For intensive cocoa and oil palm systems planted in short fallows, land
use is assumed to shift from a Chromolaena
odorata short fallow intercrop to a perennial tree crop system. Extensive cocoa and oil palm systems planted
in forested fallow involve conversion of either long fallow or forest land to a
perennial tree crop system. The starting
point of a particular land conversion process has enormous importance for
whether there will be gains or losses in terms of GEBs. The rehabilitation of degraded short
fallow-crop rotation systems with perennial systems is a clear objective of the
ASB program.
The same starting point argument holds for the soil
structure component of agricultural sustainability. The shift from a short fallow/annual crop
cycle to a perennial tree crop system such as shaded cocoa can result in an
improvement in soil structure. However,
nutrient export levels may be increased, resulting in lowered soil fertility.
For the intercrop food field in a short fallow rotation, the
major concerns are relatively low profitability, agricultural sustainability
and the low levels of biodiversity and carbon stocks. There are potential concerns surrounding soil
structure, nutrient export and pests and disease with this field system,
especially as the number of crop-fallow cycles increases and as the soil
restoration period, i.e., fallow, shortens.
The nutrient export of this system was intermediate; however, soil
exposure was higher than for any other system, indicating possible erosion
potential. Given the central role of
this cropping system in the social fabric of village life and the
underdeveloped rural food markets of the Congo
basin, efforts to replace this slash-and-burn system are likely to fail in the
near and mid-term. Efforts to improve
the productivity of this system should focus on the introduction of improved varieties
of groundnuts, cassava and maize, in combination with integrated soil fertility
management. Fertility management should
combine the improvement of the soil restorative component of the fallow period
with the strategic use of fertilizers (particularly in areas with developed
input markets and good rural roads).
The major tradeoffs surrounding the intercrop food field in
a long fallow rotation are the low profitability of the system and the decrease
in carbon stocks and biodiversity. This
system, the principal components of which are Cucumeropsis mannii, plantain banana and cocoyams (Xanthosoma sagitiifolium), assumes a
relatively land-abundant household, which limits its extent in areas where
population pressures are high. However,
in areas where land is still abundant and populations are low, market
infrastructure and institutional development can also be limiting factors. The starting point for land-use change in
this system is the forest; thus, there are also concerns over a decline in
global environmental benefits if this extensive system increases in area. Low profitability (returns to labor = $1.70
per person day) and the negative environmental effects associated with this
extensive system would be ameliorated by an increase in agricultural research
targeting the three principal crops—Cucumeropsis
manni, cocoyam (Xanthosoma
sagitiifolium) and plantain—which have been largely neglected by
agricultural research to date. The
relatively fertile, high biomass and subsequent high input of ash fertilization
following the burn of a long fallow warrants the development of nutrient
efficient varieties and crop management interventions to exploit the relatively
fertile environment. Developing nutrient
efficient varieties, along with their multiplication and distribution to
farmers, presents a major institutional challenge for research and development
in the Congo
basin. There is the “Pandora’s box”
issue of whether or not an increase in land and labor productivity would lead
to an expansion in this land use type and further deforestation. This valid concern would be assuaged by
broad-based productivity increases in land-use systems. To achieve this difficult task will require a
balanced agenda involving multi-institutional collaboration on the research and
development of the major components of the Congo
basin farming systems. The Pandora’s box
issue will also be a function of the size of output markets and the elasticity
of demand. If, as is likely, they are
small, then an increase in productivity of these systems would most likely
deflect pressure to further clear new forest.
Both of the crop-fallow rotational systems are likely to remain
important across the Congo
basin and should be the focus of land-saving and labor-neutral or labor-saving
interventions. Abating the environmental loss associated with extensive
slash-and-burn systems will require both alternative perennial systems capable
of sustaining rural livelihoods and more productive slash-and-burn systems. The latter would permit farmers to convert
land currently in these crop-fallow systems to what are arguably more
agronomically sustainable perennial tree crop systems.
The intensive cocoa system with fruit trees planted to short
fallow is among the most profitable of the systems examined (returns to labor =
$2.36 per person-day). Both biodiversity
and carbon sequestration (time-averaged, above-ground carbon stock values
increase from 4.5 to 61 tons ha-1 yr-1) would increase
following a shift from a short crop/fallow land use to a perennial tree crop
system. However, there are concerns
about the agronomic sustainability associated with the high incidence of pest
attack (capsid insects, Phytoptera
palmivora and Phytoptera megakarya),
which can result in losses of up to 80 percent.
Both intensive cocoa systems receive cautionary scores on soil
structure, as the higher level of management and human traffic may lead to the
higher bulk density noted in cocoa plantations relative to other land covers.
The elevated productivityof this system is a function of an increase in labor
and pesticide input. Institutional
constraints in many areas of the Congo
basin, such as the unavailability of inputs and scarce labor availability, are
likely to limit the extent of this particular land-use system. The fruit tree component contributes
significantly to the profitability of this system, but because of the
relatively low value to weight ratio of fruit, it results in increasing
transportation costs with distance to market.
The underdeveloped road infrastructure of the Congo
basin will also be a constraint to the development of this multi-strata complex
agroforestry system. The most extensive
extrapolation domains for this particular system are likely to lie in the more
densely populated, humid forest areas of West Africa (Ghana,
Cote d’Ivoire, Nigeria,
and Togo),
where cocoa production is already a significant cash crop activity and market
institutions are more robust. The
intensive cocoa system without fruit trees planted to short fallow is subject
to the same set of tradeoffs as above, with the exception of the need for urban
market access. Pesticide and labor
constraints correspond exactly.
Extensive cocoa systems with fruit trees planted in forest
land are moderately profitable (returns to labor = $2.03 per person-day) but
entail a significant decline in global environmental benefits (declines in
carbon stocks from 210 to 65 tons ha-1 yr-1 ). If instead of forest land, these systems are
targeted to be planted in long fallow-crop rotations, there would be negligible
environmental change. The issue of agronomic
sustainability for extensive cocoa is mainly a question of pest
management. In these extensive systems
the lack of capsid control, which can destroy the productive potential of the
tree stock, is a great concern.
Institutional and labor constraints attached to cocoa production are
less than the intensive cocoa systems.
Urban market access will, however, limit the extent of this system. The extensive cocoa system without fruit
trees is the least profitable of any system considered (returns to labor =
$1.63 per person-day). The agronomic
sustainability of this system is also subject to the problems associated with
capsid control. The nutrient cycling and
relatively low yields in these shade canopy systems result in a favorable
nutrient balance score.
The oil palm system planted on forest land is the most
profitable of all land use systems considered, with an estimated return to
labor of $2.44 per person-day.
Profitability is increased substantially by food intercropping during
the first two years, in particular by the possibility of producing 10 tons of
plantains in the second year. Global
environmental tradeoffs are the most pressing.
Time-averaged carbon stocks decline from 211 to 61 ha-1 yr-1 and, although biodiversity
measures were not taken, there is little doubt about the lack of plant and
faunal diversity in these monoculture systems.
When planted in short fallow fields, yields at maturity are 6% lower
than the same system planted on forest land, due to differences in soil
fertility, and the returns from plantain production during the establishment
intercrop are much lower. As a result, profitability declines to $ 1.81 per
person-day. Institutional and
organizational constraints are significant for these oil palm systems. Post-harvest processing must normally occur
within 48 hours of harvest. There are
also likely to be scale economies in both time and space, which will warrant
some type of collective action in the processing phase. There is also the
organizational issue surrounding the multiplication and distribution of
improved “Tenera” hybrid material.
Currently there are only two suppliers--the national research institute
and a parastatal industrial oil palm plantation charging 200 to 250 FCFA per
germinated seed and wielding significant market power. The ready supply and distribution of these
highly productive hybrids is likely to be a major constraint to the development
of small scale oil palm production systems throughout the Congo
basin and, to a lesser degree, West Africa.
Communal management of forest lands for commercial timber
production and other purposes received positive scores on all environmental and
sustainability accounts, although the sustainable commercial harvest of
tropical timbers has proven to be an elusive goal for many timber
companies. The financial incentives
attached to the commercial harvest of timber could be a deterrent to the
practice of slash-and-burn agriculture.
However, there are numerous institutional and regulatory issues that a
community has to resolve before it can obtain legal community tenure to
timber. As currently written, the
state-imposed regulatory framework requires more than 20 procedures in order to
obtain community tenure. There are also
many collective action problems associated with distribution of benefits,
sanctions, and free-ridership.
Overcoming these obstacles is a necessary condition if slash-and-burn
farming communities are to limit their agricultural activities to areas outside
the community forest.
Tradeoffs Across Land Use Systems
Comparing biodiversity and social profitability across
systems, the two intensive cocoa and the extensive cocoa system with fruit
trees offer both relatively high profitability while maintaining a satisfactory
level of biodiversity (Figure 8). In
contrast, the crop/fallow rotational systems and the short fallow/oil palm
system perform rather inadequately on both accounts. For both these systems and the monocrop oil
palm system planted in forest land, biodiversity will be sacrificed for
increased profitability, as the possibility
of augmenting the biodiversity in these systems is low (unlike the potential
for increasing their productivity and profitability). Although information was not collected on
social profitability on a per hectare basis for the community forest, its value
is probably low (although the returns to labor may be high). For illustrative
purposes we have included it, assuming a value of $25 per ha for the collection
of non-timber forest products (higher than that measured in Indonesia). The successful implementation of the
institutional reform on community tenure of timber rights would increase the
social profitability of this land use system and serve as a deterrent to
deforestation by slash-and-burn agricultural communities at the forest margin. The impact on biodiversity of sustainable
logging practices remains a question.
The ecological relationships among biodiversity, management
practices and productivity are an area for future research, especially in the
relatively species-rich cocoa agroforests.
Specifically, interactions between entomopathogenic fungi, plant
functional attributes, ant and termite mosaics, applications of copper
fungicides and the population dynamics of Phytoptera
spp. are important for strategic research.
In terms of tradeoffs between carbon stocks and
biodiversity, there is, in general (with the exception of the oil palm
monoculture systems), a direct and positive correlation between the
time-averaged carbon stock in a system and plant biodiversity.
Both carbon stocks and social profitability are high for the
intensive cocoa, extensive cocoa with fruit and the hybrid oil palm in forest
land systems (Figure 9). The tradeoff
between profitability and carbon stocks is less significant for oil palm
systems than that of biodiversity. The
short fallow-intercrop rotation performs the worst in the carbon profitability
tradeoff. The long-fallow intercrop
rotation is comparable to the perennial tree crop systems in terms of
time-averaged carbon; however, the social profitability of this land-use system
is low. Long fallow systems, though
relatively sustainable in the long run, are found only under conditions of low
population density. This is, however, a
widespread domain in the Congo
basin.
Unlike biodiversity, the carbon stocks in these systems are
amenable to change and system performance can be improved. For instance, typical existing short fallow-intercrop
rotations were estimated to have a time-averaged value of carbon equal to 4.53
tons and a carbon accumulation rate of 2.90 tons ha-1 during the
fallow period. However, on-station work
with improved fallow interventions has shown an average accumulation of up to
10 tons of carbon using leguminous tree species such as Calliandra spp. A short fallow-intercrop rotation with
Calliandra, accumulating carbon at 5 tons ha-1 would increase the time-averaged
carbon stock value of this system to 6 tons ha-1 (an increase of 25
%). All of the cocoa systems modeled
incorporate a shade canopy, which is a major source of carbon in these
systems. Increasing the density of the
shade canopy will result in a higher level of carbon stock. Shade management has important implications
for pest populations, yields and agronomic sustainability. The maintenance of these systems in some
cases for over 60 years
with virtually no fertilizer applications is a testimony to the tight nutrient
cycles of these systems.
The relationship between social profitability and the
farmer’s return to his or her labor is shown in
Figure 9. The relatively linear
relationship between these two sets of indicators implies that there are not
large distortions between social prices and farmer (i.e. financial) prices. In
other words, the most socially profitable land use systems also tend to be the
most profitable for farmers.
At current prices, the oil palm planted in forested land and
the intensive cocoa system with fruit are roughly equivalent in terms of both
social profitability and the financial returns to labor. In terms of effective rates of protection,
the intensive cocoa system with fruit trees had a slightly lower ratio
(0.90) than did the oil palm system
(0.92), indicating a relatively higher rate of taxation in the cocoa sector.[1] Taxation in the cocoa sector (mainly
consisting of import tariffs on pesticides and a 10 % excise tax on production)
is significantly lower today than when the national marketing board was
operating and official producer prices were set by presidential decree. While cocoa farmers are now under a less
taxing price regime, there is also more price uncertainty.
Figure 10 also illustrates the impact that an overvalued
FCFA can have on farmer returns. We
assumed for the case of intensive cocoa with fruit that the FCFA was overvalued
by 50%. Under this scenario the producer’s
return to labor ($1.36) would be lower for than the slash –and-burn
systems. Farmers facing this type of
incentive structure would be expected to shift
labor out of cocoa and into the production of annual food
crops, despite the much higher social profitability of producing cocoa. Prior to the devaluation in 1994, the
overvalued FCFA was a source of heavy implicit taxation for producers of
tradeable commodities such as
oil palm and cocoa, and there was a noticeable impact felt
in the Yaounde food market. In contrast to export crops, an overvalued
exchange rate has little impact on farmer incentives for commercial food
production because of the nontradeable nature of the most important food crops
in the humid forest zone (i.e. plantains, cocoyams and cassava). Overall, the effect of the overvalued FCFA
was to favor food production systems over export crops such as coffee, cocoa
and oil palm.
Å = improvement/maintenance of
status quo in GEB or AS Å = favorable to adoption
() indicates tentative finding
with further verification required
- indicates no data collected