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Influence of tree cover on diversity, carbon sequestration and productivity of cocoa systems in the Ecuadorian Amazon

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Influence of tree cover on diversity, carbon sequestration and productivity of cocoa systems in the Ecuadorian Amazon

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Cocoa production in the Ecuadorian Amazon is an important source of income for the local population. There is a wide variety of cocoa production systems, from enriched primary forests to traditional agroforestry systems and monoculture. This study assesses the relationship between tree diversity, carbon stocks, agricultural productivity and forest use potential under three land use systems in the Ecuadorian Amazon: cocoa-based agroforestry (Cocoa AFS), cocoa monoculture (Monoculture) and primary forest (PF). Understanding and quantifying the tradeoffs between different ecosystem services related to cocoa production systems can contribute to the conservation of primary forests and help to optimize income for local people. Species richness, beta-diversity, carbon stocks (above- and below-ground biomass, necromass and soil), and cocoa and timber production were determined for each system in 1,600 m2 study plots (n=28). The results show that beta diversity, species richness and carbon stocks were significantly higher in PF and Cocoa AFS, whereas cocoa production was 1.5 times higher in the Monoculture than in Cocoa AFS. In both cocoa systems, species richness, beta diversity and total C were negatively correlated with cocoa productivity. Although our results show that cocoa monoculture was more profitable than Cocoa AFS for the farmers, a monetary payment based on carbon credits for avoided deforestation could be a viable strategy to support the implementation of Cocoa AFS, which would help conservation efforts and climate change mitigation while sustaining commercial cocoa production in the area.
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Photo 1.
Cocoa agroforestry system “chakra” one of the most important traditional agricultural
systems in the Sumaco Biosphere Reserve (SBR).
Photograph O. Jadán, 2011.
Oswaldo Jadán1
Miguel Cifuentes2
Bolier Torres3, 4
Daniela selesi5
Dario Veintimilla6
Sven Günter2, 7
1 Universidad de Cuenca
Carrera de Ingeniería
Agronómica
Campus Yanuncay
Cuenca
Ecuador
2 CATIE
Sede Central
7170 Cartago
Turrialba 30501
Costa Rica
3 Universidad Estatal
Amazónica
Department of Life Sciences
Km 21/2 Vía Napo
Puyo-Pastaza
Ecuador
4 Institute of Forest
Management
Center of Life and Food
Sciences
Weihenstephan Technische
Universität München
Freising
Germany
5 Humboldt University of Berlín
Unter den Linden 6
10099 Berlin
Germany
6 Institute of Silviculture
Technical University of Munich
Arcisstraße 21
80333 München
Germany
7 Thünen-Institute
of International Forestry
and Forest Economics
Leuschnerstraße 91
21031 Hamburg-Bergedorf
Germany
Influence of tree cover
on diversity, carbon
sequestration and productivity
of cocoa systems
in the Ecuadorian Amazon
Bois et forêts des tropiques, 2015, n° 325 (3)
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35
Bois et forêts des tropiques, 2015, n° 325 (3)
diVersitY, CArBon stoCK And CoCoA sYsteMs produCtiVitY
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RÉSUMÉ
INFLUENCE DU COUVERT FORESTIER
SUR LA DIVERSITÉ, LES STOCKS
DE CARBONE ET LA PRODUCTIVITÉ
DES CACAOYÈRES DANS LA RÉGION
AMAZONIENNE DE L’ÉQUATEUR
La production de cacao dans la région ama-
zonienne de l’Équateur représente une
source de revenus importante pour la popu-
lation locale. Les systèmes de production de
cacao varient entre forêt primaire enrichie,
systèmes agroforestiers traditionnels et
monoculture. Cette étude vise à évaluer la
relation entre diversité spécifique, stocks de
carbone, productivité agricole et utilisations
potentielles des ressources forestières pour
trois modes d’utilisation des terres dans la
région amazonienne de l’Équateur : agrofo-
resterie à dominante cacaoyère (AF Cacao),
monoculture de cacao (Monoculture) et forêt
primaire (FP). La connaissance et la quanti-
fication des meilleurs compromis entre les
différents services écosystémiques liés à
la culture du cacao permettent de contri-
buer à la conservation des forêts primaires
et d’optimiser les revenus des populations
locales. La richesse spécifique, la diver-
sité bêta, les stocks de carbone (biomasse
aérienne et souterraine, nécromasse et sols)
et la production de cacao et de bois ont été
déterminés pour chaque système de culture
sur des parcelles de 1 600 m2 (n = 28). Nos
résultats montrent que la diversité bêta, la
richesse spécifique et les stocks de carbone
sont significativement plus élevés dans les
systèmes FP et AF Cacao, tandis que la pro-
duction du cacao est 1,5 fois plus élevée
en Monoculture que sur les parcelles en AF
Cacao. Pour ces deux systèmes, la richesse
spécifique, la diversité bêta et les stocks de
carbone totaux sont corrélés négativement
avec la productivité de cacao. Alors que nos
résultats montrent que la monoculture de
cacao est plus rentable pour les agriculteurs
que l’AF Cacao, un système de rémunération
monétaire de la déforestation évitée, basé
sur les crédits carbone, pourrait représenter
une stratégie viable pour encourager la mise
en œuvre de systèmes AF Cacao, lesquels
contribueraient aux efforts de conservation
et d’atténuation des effets du changement
climatique tout en permettant de maintenir
une production commerciale de cacao dans
la région.
Mots-clés : cacao, systèmes agroforestiers,
forêts primaires, Chakra, monoculture,
Sumaco, carbone.
ABSTRACT
INFLUENCE OF TREE COVER ON
DIVERSITY, CARBON SEQUESTRATION
AND PRODUCTIVITY OF COCOA
SYSTEMS IN THE ECUADORIAN
AMAZON
Cocoa production in the Ecuadorian Ama-
zon is an important source of income for the
local population. There is a wide variety of
cocoa production systems, from enriched
primary forests to traditional agroforestry
systems and monoculture. This study asses-
ses the relationship between tree diver-
sity, carbon stocks, agricultural productivity
and forest use potential under three land
use systems in the Ecuadorian Amazon:
cocoa-based agroforestry (Cocoa AFS),
cocoa monoculture (Monoculture) and pri-
mary forest (PF). Understanding and quan-
tifying the tradeoffs between different eco-
system services related to cocoa production
systems can contribute to the conservation
of primary forests and help to optimize
income for local people. Species richness,
beta-diversity, carbon stocks (above- and
below-ground biomass, necromass and soil),
and cocoa and timber production were
determined for each system in 1,600 m2
study plots (n=28). The results show that
beta diversity, species richness and carbon
stocks were significantly higher in PF and
Cocoa AFS, whereas cocoa production was
1.5 times higher in the Monoculture than in
Cocoa AFS. In both cocoa systems, species
richness, beta diversity and total C were
negatively correlated with cocoa produc-
tivity. Although our results show that co-
coa monoculture was more profitable than
Cocoa AFS for the farmers, a monetary pay-
ment based on carbon credits for avoided
deforestation could be a viable strategy to
support the implementation of Cocoa AFS,
which would help conservation efforts and
climate change mitigation while sustaining
commercial cocoa production in the area.
Keywords: cocoa, agroforestry systems, pri-
mary forests, Chakra, monoculture, Sumaco,
carbon.
RESUMEN
INFLUENCIA DE LA CUBIERTA FORESTAL
EN LA DIVERSIDAD, ALMACENAMIENTO
DE CARBONO Y PRODUCTIVIDAD
DE SISTEMAS DE CACAO
EN LA AMAZONÍA ECUATORIANA
La producción de cacao en la Amazonía
ecuatoriana constituye una importante
fuente de ingresos para la población local.
Los sistemas de producción de cacao son
variados y engloban bosques primarios
enriquecidos, sistemas agroforestales tra-
dicionales y monocultivos. El objetivo de
este estudio es evaluar la relación entre
diversidad específica, reservas de carbono,
productividad agrícola y usos potenciales
de los recursos forestales en tres sistemas
de uso de la tierra de la Amazonía ecuatoria-
na: agroforestería con predominio de cacao
(AF Cacao), monocultivo de cacao (Mono-
cultivo) y bosque primario (BP). La compren-
sión y cuantificación de las compensaciones
recíprocas entre los diferentes servicios
ecosistémicos relacionados con el cultivo de
cacao puede contribuir a la conservación de
los bosques primarios y optimizar los ingre-
sos de la población local. En cada sistema
de cultivo, en parcelas de 1 600 m2 (n=28),
se determinó la riqueza específica, diver-
sidad beta, reservas de carbono (biomasa
aérea y subterránea, necromasa y suelo) y
la producción de cacao y madera. Nuestros
resultados muestran que la diversidad beta,
la riqueza específica y las reservas de car-
bono son significativamente mayores en
los sistemas BP y AF Cacao, mientras que la
producción de cacao es 1.5 veces mayor en
Monocultivo que en las parcelas AF Cacao.
En estos dos sistemas, la riqueza específica,
la diversidad beta y las reservas de carbono
totales están negativamente correlaciona-
das con la productividad de cacao. Aunque
nuestros resultados muestran que el mono-
cultivo de cacao es más rentable para los
agricultores que la AF Cacao, se podría apli-
car una retribución monetaria por defores-
tación evitada basada en los bonos de car-
bono. Esto podría ser una estrategia viable
para favorecer la implantación de sistemas
AF Cacao, que contribuirían a los esfuerzos
de conservación y mitigación de los efectos
del cambio climático, permitiendo al mismo
tiempo mantener una producción comercial
de cacao en la región.
Palabras clave: cacao, sistemas agro-
forestales, bosques primarios, chacra,
monocultivo, Sumaco, carbono.
O. Jadán, M. Cifuentes, B. Torres,
D. Selesi, D. Veintimilla, S. Günter
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37
indigenous groups (Porro et al., 2012). Locally known as
“Chakra” (photo 1), they consist of small plots within the
rainforest that are used to plant subsistence crops
(photo 2); a traditional practice carried out over centuries
by the local Kichwa population (Whitten and Whitten, 2008).
Over time, the cultivation of staple food such as manioc,
Manihot sculenta, peach palm, Bactris gasipaes, and
banana, Musa paradisiaca, were integrated with other com-
mercially valuable species such as cocoa, Theobroma cacao
(Torres et al., 2014). Aside from its economic importance,
the “Chakra” also provides social and cultural goods to the
farmers (Selesi, 2013). Interestingly, the “Chakra” cacao
system is one of the most important land use systems in the
SBR, after native forests and livestock farming (Selesi,
2013), with about 12,000 farmers practicing this production
system (75% of whom are indigenous farmers) in over
14,000 hectares (Torres et al., 2014).
The presence of timber species within cocoa planta-
tions, such as in the “Chakra” system, provides an added
value to the production of cocoa and improves profitability in
Introduction
Deforestation to expand conventional farming systems
is the major cause for the continuing loss of tropical ecosys-
tems (Seufert et al., 2012). Over the last decade, such land
use changes have been responsible for around 10% of
global CO2 emissions (Le Quéré et al., 2013). In the Ecua-
dorian Amazon, loss of natural ecosystems is particularly
evident in areas of high biodiversity. For instance, in the
Sumaco Biosphere Reserve (SBR), between 2008 and 2013,
the deforestation rate was 3.34%, mainly due to anthro-
pogenic processes such land use changes for livestock
and agricultural production (Ministerio del Ambiente del
Ecuador and Deutsche Gesellschaft für Internationale
Zusammenarbeit, 2013).
In that region, conventional agricultural production sys-
tems are mostly based on monocultures with typically low
long-term productivity (Price and Norsworthy, 2013). In con-
trast, it is also possible to find traditional and originally
organic farming production systems, mainly practiced by
Photo 2.
Chakra subsistence contributes to food security for population in Biosphere Reserve Sumaco.
Photograph O. Jadán, 2011.
Bois et forêts des tropiques, 2015, n° 325 (3)
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Forest life zone (Holdridge, 1967), with mean annual tempera-
ture of 23°C, mean annual precipitation of 3,500 mm, and
distinct wet (April-May) and dry (October-December) seasons
(Inamhi, 2014).
Participating farms were selected among the members of
the Napo-Kallari cocoa growers association. The criteria for the
initial farm selection were: a) crop area ≥ 0.5 ha, b) tree crown
cover 10% in cocoa AFS and < 10% in cocoa Monoculture,
determined with a densiometer as in Guilherme (2000), c)
cultivation in cocoa AFS must be organic, and d) all study sites
had to be planted with the same, “national”, cocoa variety.
A total of 300 farms meeting these characteristics were identi-
fied (195 AFS and 105 Monoculture), from which 23 were
selected randomly (15 AFS and 8 Monoculture, 8% of initially
selected farms) and based on the willingness of the farmers to
participate in the study. In each farm, one 1,600 m circular plot
was installed. For comparison to the cocoa systems, five sim-
ilar study plots were installed in a primary forest located at the
Jatun Sacha Biological Station (JSBS), thus totaling 28 study
plots distributed among the three land use types.
Richness and floristic diversity
Within each study plot, diameter and commercial height
of all trees and palms with a diameter at breast height (dbh)
the long run (Ramirez et al., 2001). Thus, cocoa-based agrofor-
estry systems (cocoa AFS) maintain productivity, functionality
and economic efficiency of crops while showing a yet to be
determined climate change mitigation potential (Verchot et al.,
2007). To the best of our knowledge, this is the first study in
which a complete assessment of the potential of cocoa AFS for
climate change mitigation is reported. The objective of this pro-
ject was to determine the influence of tree cover on richness
and floristic diversity, carbon stocks, ecosystem services, agri-
cultural productivity and silvicultural utilization potential under
three land use systems (LUS) and to determine the relation of
these variables with the agricultural management under
organic and conventional practices in the Ecuadorian Amazon.
Cocoa Monoculture and cocoa AFS were compared with each
other and against Primary forest (PF) (photo 3).
Methods
Study sites
The study sites were located in the lower part of the SBR in
the cantons of Archidona and Tena, Napo Province, Ecuador
(figure 1). The SBR comprises 88,000 hectares at elevations
under 700 m. The climate is typical of Holdridge’s Tropical Wet
Photo 3.
Systems of land use evaluated: 1) primary forest, 2) cocoa AFS and 3) monoculture.
Photograph O. Jadán, 2011.
Bois et forêts des tropiques, 2015, n° 325 (3)
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10 cm were measured and their species identified.
EstimateS v.5.0.1 (Colwell, 2011) was used to calculate den-
sity of individuals per hectare, dominance, species richness
and beta diversity. Beta diversity was calculated using an
analysis of similarities (ANOSIM) and non-metric multidi-
mensional scaling (NMS) using Bray Curtis as dissimilarity
measure in species composition.
Carbon storage and accumulation rate
Biomass was divided into five storage components;
aboveground biomass, belowground biomass (roots), litter
(branches < 10 cm in diameter and leaves), necromass (> 10 cm
diameter) and soil. Aboveground biomass was classified
according to the physiognomy of its components: cocoa trees,
timber trees, fruit trees, Musaceae and palms. Above and
below ground biomass for these were estimated using allo-
metric equations (table I). Litter samples were taken from four
1 m2 subsamples per plot and dried to constant mass. Necro-
mass (> 10 cm diameter) was measured along two 23 m-long
transects, laid out perpendicularly to each other and bisecting
the study plot (Penman et al., 2003). Composite soil samples
from four randomly located points per plot were taken to esti-
mate soil C at two depths (0-10 cm and 10-30 cm).
Total soil C was determined by dry combustion (Mac-
dicken, 1997). Carbon (C) was estimated as 0.5 of the bio-
mass (Penman et al., 2003) and total carbon (TC) as the sum
of all storage components. Carbon equivalence (CO2e) was cal-
culated by multiplying C values by the molecular equivalence
factor 3.67. We used an annual C accumulation rate of
0.45 Mg/ha/yr- for PF (Lewis et al., 2009) and of 1.3 Mg/ha/yr-
Table I.
Allometric equations for biomass estimation, calculating C accumulation rate, productivity
and income for three land use systems evaluated in the Sumaco Biosphere Reserve, Ecuador.
Ecosystem or species Equation Range DBH
(cm) R2Author
Tropical forests Ln (Bt)= -1.864+2.608 × Ln (dap) + Ln (d) 5 - 150 0.99 (Chave et al., 2005)
Bactris gasipaes Bt = 0.74 × h2 0.95 (Szott et al., 1993)
Cocoa Bt = 1.0408 exp0.0736 × (d30) 0.97 (Torres et al., 2014)
Saplings Bt = 10(-1.27+2.2 × Log (dap)) 0.3 - 9.3 0.88 (Andrade et al., 2008)
Musaceae Bt = (185.1209 + 881.9471 × (Log(ht)/
ht2))/1000 (Villavicencio, 2009)
Palms Bt =7.7 × ht + 4.5 0.90 (Frangi and Lugo, 1985)
Roots Br = exp (-1.0587 + 0.8836 × Ln Bt) 0.84 (Penman et al., 2003)
Accumulation rate IAt = CBT / e (Equation 1)
Cocoa productivity Pc = Nfl × 0.136 kg × (Equation 2)
Net revenue cocoa IN = ITp – Cp (Equation 3)
Notes: R2: adjusted R2; Bt: total aboveground biomass (kg/tree); Br: belowground biomass; DBH: diameter at breast height (cm);
d: basic wood density; d30: diameter at 30 cm height ; ht: total height (m); exp: power base e ; Ln: natural logarithm (base e);
IAt: annual increment of each plant type (Mg C/ha/yr); CBT: carbon stored in the total biomass of each plant (Mg C/ha/yr),
e: estimated age of each plant; Pc: productivity cocoa (kg/ha); Nfl: total number of pods per plot; Sm: sampling surface; IN: net revenue;
ITp: total income per production cocoa; Cp: production costs cocoa.
Figure 1.
Study area in Sumaco Biosphere Reserve, Napo Province,
Ecuador.
Reserve Biosphere
Sumaco
Study arca Research sites
Archidona
Tena
0
78°0'0"W 77°50'0"W 77°40'0"W 77°20'0"W77°30'0"W
78°0'0"W
0°30'0"S
0°40'0"S
0°50'0"S
1°0'0"S
1°10'0"S
0°30'0"S
0°40'0"S
0°50'0"S
1°0'0"S
1°10'0"S
77°50'0"W 77°40'0"W 77°20'0"W77°30'0"W
5 10 20 Kilometers
Biosphere Reserve Sumaco
in Republic of Ecuador
Study arca and research sites
within the cantons Tena
and Archidona
Columbia
Ecuador
Perú
Bois et forêts des tropiques, 2015, n° 325 (3)
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cocoa growers association. This value was used to calculate
the total income from cocoa production (ITp). Net cocoa
revenue was calculated with Equation 3 (table I). The commer-
cial timber volume was based upon a net income of 8 USD/m3
for softwoods and 45 USD/m3 for hardwoods (Gatter and
Romero, 2005). The total monetary value of timber was divided
according to rotation periods defined in the national forest
regulations (Ministerio del Ambiente del Ecuador, 2010). Poten-
tial revenue from CO2e sales was estimated using a price of
5 USD for CO2/ha and financial scenarios between forest
C stocks and crops were compared within the REDD+ context
(Peters-Stanley and Gonzalez, 2014).
Statistical analysis
LUS variables and differences were analyzed using
ANOVA, Fisher LSD test and Pearson’s correlation coefficient
at a 95% confidence level.
Results
Richness and floristic diversity
We found more species per area and more sampled indi-
viduals in PF than in Cocoa AFS and in Monoculture
(p < 0.05; figure 2). According to these curves, a one-hec-
tare forest was estimated to have 225 species, compared to
35 species.ha-1 in Cocoa AFS and only 10 species/ha in the
Monoculture.
Species richness, density of individuals per hectare
(Ind/ha), basal area (m2/ha) and canopy cover (%) were
higher in PF than in both cocoa AFS and Monoculture
(p < 0.009). Cocoa AFS shared the greatest number
of species (19) with PF (table II).
Beta diversity showed significant differences in species
composition between the three land uses (R2 = 0.70,
p = 0.001). The results of the NMS and ANOSIM (figure 3)
for the species composition was significantly higher in PF
than in Cocoa AFS (p = 0.001) and in Monoculture
(p = 0.012). The species composition between cocoa
farming types was statistically different (p = 0.009).
Carbon storage and accumulation
Aboveground and belowground C and total C were 4 to
36 times greater in PF than in Cocoa AFS and Monoculture
systems (p < 0.009). There were no significant differences
(p = 0.6917) of C in necromas and soil (p = 0.6917) among
the LUS. The annual increment of total C was significantly
higher (p = 0.0001) in Cocoa AFS than in the Monoculture
and PF (table III).
Production and potential revenue
Cocoa production was 1.5 times higher (p = 0.0522) in
Monoculture than in Cocoa AFS. Consequently, net cash
income from cocoa productivity was similarly higher in the
monoculture than in cocoa AFS (p = 0.0587). Although
for soils across all LUS (Silver et al., 2000). To estimate the C
accumulation rate for trees and palms in LUS with cocoa culti-
vation, the DBH was used to estimate the age, assuming a
growth of 1 cm/yr (Korning and Balslev, 1994 ; Calero, 2008). In
farming systems the rate of accumulation was calculated using
Equation 1 (table I).
Agricultural and forest productivity
Cocoa productivity was calculated counting all fruits in
the study plots during the wet (April-May) and dry seasons
(October-November). All fruits were counted disregarding
phytosanitary status or maturity stage and avoiding double
counting. Wet pulp weight (the product typically sold by the
Kichwa population) was measured on 50 mature fruits at
each sampling time (photo 4). Potential cocoa productivity
was then calculated using Equation 2 (table I). Off-season
productivity was considered negligible, based on local inter-
views and direct observations. Timber production was cal-
culated with the commercial volume information obtained
from the floristic inventory.
Costs, revenue and valuation
Agricultural production costs
Production costs were calculated in each agricultural
system during one year. For cocoa, we considered fertiliza-
tion (conventional and organic), weed control (manual
weeding), phytosanitary control, shade regulation, pruning
and harvesting costs.
Total net revenue
The sale price of wet cocoa pulp was 1.21 USD/kg, which is
the local “fair market” price paid to the local Napo-Kallari
Photo 4.
Fruit harvesting for calculating productivity in the cocoa SAF.
Photograph O. Jadán, 2011.
Bois et forêts des tropiques, 2015, n° 325 (3)
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41
timber production potential was 1.6 times higher in PF than
in Cocoa AFS (p = 0.5075; table IV-a), higher revenue would
come from a possible sale of C (table IV- b).
Relationship between species richness,
diversity of tree species,
carbon and productivity indicators
In PF, production and the resulting income were nega-
tively correlated with species richness (r = -0.95 and
r = -0.98; table V-a). In the Cocoa AFS, productivity was
negatively correlated with tree species richness (r = -0.53).
Forest density was positively correlated (r = 0.63) and basal
area negatively correlated (r = -0.55) with species richness
(table V-b). In contrast, in the Cocoa AFS, tree density and
percentage of tree cover were positively correlated with
species richness. Cocoa productivity was negatively corre-
lated with the percentage of tree cover. In both cocoa
systems basal area was correlated with species richness
(r = 0.64 and r = 0.77).
Figure 2.
Species accumulation curves (± standard deviation) in relation to sample area (a) and individuals (b) of trees and palms with DBH ≥ 10 cm.
The secondary axis (right side) shows the values of the primary forest.
Figure 3.
Non-metrical multidimensional scaling analysis (Bray-Curtis) and ANOSIM.
Figure shows species richness, which was shown to be significantly different
among systems.
a) b)
70 250
200
150
100
50
0
250
200
150
100
50
0
Richness (number of species)
60
50
40
30
20
10
0
Cocoa AFS
Cocoa monoculture
Primary forest
Cocoa AFS
Cocoa monoculture
Primary forest
11
2 3 4 5 6 7 8
Number of plots (0.16 ha) Number of individuals
9 10 11 11 21 31 41 51 61 71 81 91 101 111 121
12 13 14 15
70
60
50
40
30
20
10
0
Primary forest
Primary forest Cocoa monoculture
spc: shared species
2 0.5 0.012
Cocoa AFS 19 0.9 0.001
System i System j spe R2p
Cocoa monocultureCocoa AFS 10 0.4 0.009
-1.54 -0.94 -0.33 0.27 0.88
1.40
0.83
0.26
-0.31
-0.88
Cocoa AFS
Primary forest
Cocoa monoculture
Axis 1
Axis 2
Table II.
Mean ± standard error of species richness, diversity and structure of three land use systems in the Sumaco Biosphere
Reserve, Ecuador.
Variable Primary forest Cocoa AFS Cocoa monoculture
Species (richness) 53 ± 4.5 a 9.3 ± 1.3 b 1.5 ± 0.8 c
Shared species with forest and Sorensen index - 19 - 0.158 2 - 0.02
Abundance (Ind/ha) 633.8 ± 65.4 a 169.6 ± 19.7 b 25 ± 10.5 c
Basal area (m2/ha) 37.7 ± 4.1 a 10.1 ± 1.2 b 1 ± 0.5 c
% Canopy cover 95.1 ± 16.9 a 40.9 ± 3 b 4.6 ± 1.9 c
ANDEVA Fisher p < 0.05; different letters indicate statistically different values.
Bois et forêts des tropiques, 2015, n° 325 (3)
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42
Kichwas from Ecuador (Whitten and Whitten, 2008). In the
latter systems, in addition to cocoa, other tree species are
included that increase the tree cover of the cocoa plantation
above levels observed under cocoa monoculture (Selesi,
2013). In the Sumaco region, cocoa monoculture has been
subject to intense efforts for improvement through domesti-
cation and design of better production practices (Ramírez,
2006 ).
In regard to ecosystem services, cocoa monoculture
maximizes provision services through cocoa production at
the expense of carbon sequestration, biodiversity conserva-
tion and cultural identity (Seufert et al., 2012). The latter are
discussed more in detail in the following subsections.
Discussion
Management aspects of cocoa systems
In the lower part of the SBR cocoa production is particu-
larly relevant given the high demand of the product and its
contribution to the economy of local families. Management
in cocoa AFS is closely related with typical organic practices,
whereas in monocultures, management is more related with
conventional practices. Both systems have a long history of
use within the region. While monoculture systems are aimed
at maximizing production, cocoa AFS represent an instance
of the traditional agroforestry systems practiced by the
Table III.
Mean ± standard error of stored C (Mg/ha) annual carbon accumulation rate (Mg C/ha/yr) of the three LUS evaluated in
the Sumaco Biosphere Reserve, Ecuador.
Variable Primary forest Cocoa AFS Cocoa
monoculture p
Carbon in aboveground biomass
(Mg C/ha) 206.2 ± 32.4 a 52.7 ± 7.8 b 5.7 ± 2.6 c 0.0001
Carbon in belowground biomass
(Mg C/ha) 58 ± 8 a 15.3 ± 2 b 1.8 ± 0.8 c 0.0001
Soil carbon (Mg C/ha) 65.9 ± 8.9 a 69.2 ± 5 a 74.9 ± 6.8 a 0.6917
Carbon in necromass (Mg C/ha) 4 ± 0.8 ab 4.1 ± 0.4 a 2.8 ± 0.6 ab 0.2540
Total Carbon (CT) (Mg C/ha) 334.2 ± 47.1 a 141.4 ± 11 b 85.2 ± 8.9 c 0.0001
Accumulation rate of * CT (Mg C/ha/yr) 0.45 ± 0.01 c 4.9 ± 0.5 a 1.9 ± 0.1 b 0.0001
T accumulation rate* of CO2e for CT
(Mg CO2e/ha/yr) 1.7 ± 0.02 c 17.9 ± 1.8 a 7.4 ± 0.4 b 0.0001
ANOVA Fisher p < 0.05; different letters indicate statistically different values. Transformation factor of carbon stock C to its equivalent
in CO2= C × 3.67. *Estimation average based on the assumption of an increment of 1 cm/ha according to data reported by Korning
and Balslev (1994) and Calero (2008).
Table IV.
Mean ± standard error of: a) agricultural and forestry productivity; b) income from agricultural activity, forestry
and potential carbon sale prices in three LUS in the lower Sumaco Biosphere Reserve, Ecuador.
Variable Primary forest Cocoa AFS Cocoa
monoculture p
a)
Productivity of cocoa-wet (kg/ha/yr) -
1,719.5 ± 227.3 a
( 573 kg/ha/yr,
cocoa-dry; relation 3:1)
2,515.1 ± 317.9 a 0.0522
Productivity of trees (m3/ha/yr) 34.2 ± 16 a 21.7 ± 9.2 a - 0.5075
b)
ITA CO2e (USD/ha/yr) 8.3 ± 0.15 c 89.7 ± 9.9 a 35.4± 0.2 b 0.0001
NI-wet cocoa (USD/ha/yr) - 1,687.1 ± 274.9 a 2,686.8 ± 417.7 a 0.0587
NI-harvestable timber (USD/ha/yr) 70 ± 51.2 a 83.8 ± 29.6 a - 0.8174
NI: net income; ITA: Income from accumulation rates.
Bois et forêts des tropiques, 2015, n° 325 (3)
diversité, stoCK de CArBone et produCtivité des CACAoYÈres
43
food and shelter for wildlife. In the Monoculture, intensifica-
tion results in few remnant trees in the plots, lowering biodi-
versity and reducing ecological functions and potential pro-
vision of ecosystem services when compared with Cocoa
AFS and PF (Ramirez et al., 2001; Torres et al., 2014) .
Our results confirm that species composition differs sig-
nificantly between primary forest and cocoa systems, which
coincides with findings from a study in Costa Rica (Deheu-
vels et al., 2014). Besides these expected findings, there are
also important differences between cacao systems. First,
agricultural management practices by farmers determine
these differences. In cocoa AFS, the tree component and its
species richness is traditionally part of the productive
system, which is closely related to the uses that people give
most plants (Selesi, 2013). For example, mean values of
species richness in the cocoa AFS (9 species) is more than
double than those reported by Suatunce et al. (2003) in
Costa Rica, in a system of cocoa trees and Musa spp., but
similar to those found in other indigenous multi-layered
cocoa system in that same study. The latter is due to the tra-
ditional type of management practiced by indigenous
farmers in the two sites; they tend to favor the presence of
Ecosystem services:
Tree diversity and carbon sequestration
and relation with agricultural management
Cocoa AFS had higher species richness than Monocul-
ture (photo 5) because of shared native tree species with
the PF (e.g. Oenocarpus bataua, Solanum sycophanta, Iri-
artea deltoidea and Wettinia maynensis) and a wide variety
of planted trees with commercial value (e.g. Cedrela odo-
rata, Cedrelinga cateniformis, Cordia alliodora, Terminalia
amazonia, and Myroxilum balsamun) and others able to pro-
vide food security to the local farmers (e.g. Bactris gasipaes,
Carica papaya, Caryodendron orinocense, Inga edulis, Inga
ilta, Persea americana, Pouoruma bicolor and Pouruma
cecropifolia). Some of these species, such as C. alliodora,
C. odorata, C. cateniformis, B. gasipaes and I. deltoidea, are
managed under traditional indigenous systems in different
tropical contexts, forming an essential part in the structure
and richness of Cocoa AFS (Suatunce et al., 2003). Cocoa
AFS also contain several tree species such as Clarisia race-
mosa, Acacia glomerosa and Vochysia braceliniae, that provide
Table V.
Pearson correlation coefficients (r) for relationships among a) productivity and monetary incomes and species richness;
b) between structural parameters abundance, basal area and canopy cover and C total, productivity and species richness
in the three LUS evaluated in the Sumaco Biosphere Reserve, Ecuador.
Variable A Variable B
Primary
forest
Cocoa AFS Cocoa monoculture
n r n r n r
a)
Cocoa productivity
(kg/ha/yr) Species richness 5 0 15 -0.53* 8 -0.45
Timber potential (m3/ha) Species richness 5 -0.95* 15 -0.01 8 0
NI-cocoa (USD/ha/yr) Species richness 5 0 15 -0.48 8 -0.48
NI-timber (USD/ha/yr) Species richness 5 -0.98*** 15 -0.05 8 0
b)
Density (Ind/ha) Total C (Mg/ha) 5 0.03 15 0.41 8 0.58
Density (Ind/ha) Cocoa productivity
(kg/ha/year) 5 0 15 -0.30 8 -0.05
Density (Ind/ha) Species richness 5 0.63*** 15 0.77*** 8 0.66
% Tree cover Total C (Mg/ha) 5 0.13 15 0.3 8 0.39
% Tree cover Cocoa productivity
(kg/ha/year) 5 0 15 -0.65* 8 -0.93***
% Tree cover Species richness 5 0.35 15 0.83*** 8 0.58
Basal area (m2/ha) C total (Mg/ha) 5 0.96 15 0.9*** 8 0.57
Basal area (m2/ha) Cocoa productivity
(kg/ha/year) 5 0 15 -0.17 8 -0.47
Basal area (m2/ha) Species richness 5 -0.55*** 15 0.64* 8 0.77*
* p < 0.05; ** p < 0.01; *** p < 0.001; C: Carbon; NI: Net income.
Bois et forêts des tropiques, 2015, n° 325 (3)
diVersitY, CArBon stoCK And CoCoA sYsteMs produCtiVitY
44
not exceed 25 years of age and are in a more dynamic
growth phase. The degree to which these estimates are
representative of individual trees (especially remnant ones)
is yet to be validated, as long-term repeated measurements
would be needed.
Potential payments
for carbon sequestration
Net income from cocoa productivity in cocoa Mono-
culture and AFS are, respectively, 76 and 18 times higher
than those yielded by the potential sale of C. Therefore, the
payment for this ecosystem service does not seem competi-
tive in comparison to cocoa production (Gilroy et al., 2014),
negatively affecting the promotion of tree cover on farms or
conventional crops. However, considering C offsets only
does not take into account additional environmental bene-
fits provided by cocoa AFS in terms of adaptation to climate
change, food security for local residents (Torres et al., 2014)
and the provision of other ecosystem services. A broader
economic valuation of the extra benefits of traditional and
conventional systems would be necessary to reach a conclusion
about the financial feasibility of promoting compensation
schemes for environmental services in these systems.
many different species from which they can obtain multiple
benefits. Second, the supply of domestic and international
markets for cocoa enhances the creation of conventional
production systems with low species richness, but accepted
and practiced by their management efficiency and profita-
bility (Ramirez et al., 2001).
Thus, we assume that the difference between manage-
ment practices is a result of cultural heritage and traditional
knowledge related to the “Chakra” concept on the one side,
while monocultures on the other side are more related to
optimization of crop productivity. Further studies are neces-
sary to show compatibility of cocoa productivity and long
term effects on cultural identity. It is also unclear whether
species composition in traditional cocoa AFS might provide
adequate synergies for enhanced productivity in cocoa culti-
vation (Somarriba et al., 2001), or if the relationship depends
heavily on shade management only, as discussed previously.
The total C stored in PF and cocoa AFS is higher than
under cocoa monoculture. C values recorded in PF are sim-
ilar to those reported by several authors for Latin America
Cifuentes-Jara (2008). Likewise, total C in cocoa AFS is sim-
ilar to that measured in similar systems in Central America
at elevations < 1,000 m (Somarriba et al., 2013). Average C
accumulation rates derived from literature are higher for
trees in cocoa systems than for PF because the former do
Photo 5.
Existence of trees, which determine greater richness of species in the cocoa SAF, opposite of monoculture.
Photograph O. Jadán, 2011.
Bois et forêts des tropiques, 2015, n° 325 (3)
diversité, stoCK de CArBone et produCtivité des CACAoYÈres
45
rationale for these choices is beyond the scope of our study,
but we can speculate that criteria used relate to any real and
perceived benefits any given species can provide in terms of
amount and quality of shade, timber and building materials,
food, traditional medicine, wildlife shelter or other cultural
values they provide. To the best of our knowledge, no studies
have systematically addressed the optimal levels of tree den-
sity and shade in these local cocoa production systems.
Cocoa productivity in Monoculture was similar to that
recorded in Guatemala (Ministerio de Agricultura, 2007). This
high productivity is associated with a high planting density
(1,111 trees/ha) and direct light incidence on the crop
(Zuidema et al., 2005). In our study, the average dry cacao
production is four times higher compared to that recorded in
Costa Rica by Deheuvels et al. (2011); (573 kg/ha/yr vs.
135 kg/ha/yr). This result may be due in part to differences in
how fruit harvesting was accounted for: in Costa Rica only
healthy and ripe fruits in fruiting peaks were counted, while
in SBR fruit were accounted for regardless of pod health and
maturity stage. However, the results obtained in our study
are within the average yields for Ecuador (500 kg/ha/yr)
(Ramírez, 2006 ). Within cocoa systems, AFS production was
25% higher than in Monoculture. However, this difference
may be compensated by higher resilience of cocoa AFS
systems, increased C stocks, timber potential, more food
security (fruit species) and benefits from other ecosystem
services, some of which are discussed below.
Conclusions
The cocoa systems analyzed have lower richness, tree
diversity and C storage than primary forest. There is also a
negative correlation between the presence of trees, cocoa
productivity and potential income from cacao production. In
fact, potential income in cocoa AFS was 1.5 times lower than
in cocoa monoculture systems. However, the tree compo-
nent of natural forest and cacao AFS is the key to the provi-
sion of ecosystem services such as C storage and species
conservation, which are not present in systems without
trees and have not been studied locally.
Higher revenues from cacao productivity in systems
without tree cover and the low amounts offered for conser-
vation or sale of C do not promote increasing tree cover to
significantly enhance C stocks. On the other hand, it is fea-
sible that the economic losses due to the establishment of
trees are largely offset by environmental benefits such as
increased C sequestration and storage, improved food secu-
rity, cultural identity compatibility and greater resilience of
production systems. In addition, the areas of greatest defor-
estation have a high potential for inclusion in REDD+ strate-
gies, even under scenarios of low market prices for C. For
these reasons, the maintenance of carbon by avoided defor-
estation, combined with the promotion of sustainable cocoa
production systems, would be a viable option to balance
conservation, diversity and climate change mitigation at the
landscape level in the Sumaco region of Ecuador. So far,
studies have focused on products and services for potential
or actual sale, but the intrinsic heritage value from these
To increase C stocks, tree richness could be increased by
introducing productive trees as has been done in other pro-
duction scenarios in Ecuador (Castro et al., 2013) and Cen-
tral America (Somarriba et al., 2013). However, according to
our results, these changes could decrease the productivity
of the cocoa Monoculture about 1.5 times, thus decreasing
revenue by 999 USD/ha/yr. Converting cocoa monoculture
to cocoa AFS would increase stocks by about 56 Mg C/ha
(table II) or 206 Mg CO2e/ha of C stored and 3 Mg C/ha/yr or
11 Mg CO2e/ha/yr of C fixed. Hence, to compensate for the
loss in cocoa revenue, each unit of stored CO2e would have
to be paid at 4.85 USD (999 USD/ha/yr i.e. 206 Mg CO2e/ha).
Because the price of C in international markets is currently
uncertain a final determination about whether or not to rec-
ommend changes to conventional production systems
cannot be made. However, we note this price for Mg CO2e
is not an overestimate by any means (Peters-Stanley and
Gonzalez, 2014), opening the possibility of at least breaking
even financially when potentially switching Monocultures
to AFS.
Furthermore, the prevailing deforestation pressure
makes remaining forests ideal candidates for avoided
deforestation schemes included in the REDD+ mechanism
(Bosetti and Frankel, 2011). To compensate the total reve-
nue loss in cocoa, landowners require a theoretical price of
2.98 USD/Mg/CO2e for avoided deforestation under mono-
culture, and 2.82 USD/Mg/CO2e for avoided degradation of
primary forests towards cocoa AFS. Both values are very
close to the current market price of C for REDD+ activities,
opening a favorable outlook to include Sumaco primary for-
ests in compensation payment regimes for avoided defor-
estation. The lower SBR, specifically in the watersheds of
the rivers Napo and Misahualli would be an excellent candi-
date for promoting avoided deforestation through this
mechanism, because between 2008 and 2013, its deforesta-
tion rate was 3.34% (Ministerio del Ambiente del Ecuador
and Deutsche Gesellschaft für Internationale Zusammenar-
beit, 2013). Thus, at the landscape scale, there are conside-
rable financially viable options to use the cocoa/forest pro-
duction land matrix to avoid deforestation and provide
some additional revenue to locals for conserving forests.
Productivity of cocoa systems
and relation with agricultural management
A diverse tree canopy is an essential component in tradi-
tional Cocoa AFS systems. However, an excess of trees and
their resulting shade limits yields compared to those
obtained under Monoculture. In fact, there was a negative
correlation between canopy cover and tree density on the
productivity of cocoa and, therefore, on income in Cocoa
AFS and Monoculture. Shade management is thus key in
balancing cocoa productivity and carbon sequestration
(Somarriba et al., 2013). However, not all tree species are
suitable for or chosen as shade components. In traditional
systems, for example, we found more species related to PF,
potentially remnants from former natural stands. This suggests
that local farmers are making conscious decisions regarding
which tree species are left standing in any given plot. The
Bois et forêts des tropiques, 2015, n° 325 (3)
diVersitY, CArBon stoCK And CoCoA sYsteMs produCtiVitY
46
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Acknowledgements
We thank to GIZ – Napo, and Kallari for economical and
logistical support in this research. We also thank Eduardo
Chica and Darwin Pucha for revising this document.
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... It can be explained by the forest aged more than 50 years while tree plantations ranged from 5 to 21-years-old during which organic matter decomposed and accumulated. Besides, the higher plant diversity in forest could enrich the soil with a diversity of organic carbon inputs that contribute to favor the SOC stock [98,99]. At a depth of 0-30 cm, the SOC stocks were similar in tree plantations and croplands, while palm groves had lower stocks. ...
... Shade trees in cocoa production systems can lead to increased yields and profitability (Waldron et al., 2015;Jezeer et al., 2017;Niether et al., 2020), improve soil fertility (Sauvadet et al., 2020), and reduce the incidence of pest species and cocoa tree disease (Bisseleua et al., 2013;Andres et al., 2018), thus buffering farmers from environmental uncertainty. They also sequester carbon (Jadan et al., 2015;Abou Rajab et al., 2016;Schroth et al., 2016) and provide a range of other ecosystem services (Vaast and Somarriba, 2014). Shade cocoa can therefore be effective in reducing the environmental impacts of forest fragmentation while offering growers the opportunity to charge a premium from the expanding market for environmentally sustainable and certified products (Asare et al., 2014;Tayleur et al., 2018). ...
Article
We undertook nearly 300 point counts of birds in cocoa plantations around Gola Rainforest National Park, eastern Sierra Leone, to assess how their vegetation structure, management and landscape context influence bird communities and the distribution of four globally threatened or forest-restricted species. Forest bird species richness, and the occurrence of Yellow-casqued Hornbill (Ceratogymna elata), were higher in abandoned than in actively managed cocoa farms. Yellow-casqued Hornbill presence was also associated with higher canopy volume and Brown-cheeked Hornbill (Bycanistes cylindricus) was associated with greater forest cover in the surrounding landscape. Overall forest bird species richness was associated with the interaction between canopy volume and proportion of forest in the surrounding landscape. Our results indicate that where forest cover is low in the landscape, low-intensity cocoa agroforestry can provide compensatory habitat for forest bird species, but when forest cover is high, cocoa that is more forest-like in structure may not lead to increased bird species richness, although it may benefit certain species. Most habitat structure variables, other than canopy volume and openness of understorey, were poor predictors of most of the variables analysed, suggesting that within the narrow range of observed production intensity, management has little impact on bird communities once productivity increases above zero by rehabilitating abandoned farms. However, over 60% of the species recorded and over half of all recorded detections were of biome-restricted species, suggesting that low-intensity cocoa plantations hold considerable conservation value. Changes in cocoa management may therefore impact those species.
... Mg ha -1 ) and Saj et al. (2013) in Cameroon (70 Mg ha -1 ). However, this last one is close to the 49 Mg ha -1 obtained by Somarriba et al. (2013) in Central America and the 52.7 Mg ha -1 obtained by Jadán et al. (2015) in the Ecuadorian Amazon. The . ...
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In the perspective of using cocoa as a response to climate change, a preliminary carbon stock assessment was conducted in cocoa agroforests of the Bengamisa-Yangambi forest landscape in the north-east of Democratic Republic of Congo (DRC). Data were collected in 25 plots of 2500 m2 each, spread over 16 villages. Above-ground carbon stock assessment on cocoa trees and their associated plants revealed that cocoa agroforests store on average 44.48 Mg ha−1 of above-ground carbon of which, cocoa-associated plants represent 83.68%. The diversity (species richness) of cocoa associated plants determine the level of above-ground carbon stored in cocoa agroforests. Trees less than 50 cm in diameter stored a larger amount of above-ground carbon. Cocoa agroforests with associated plants dominated by forest species (Model F) store 1.76 and 1.72 times more carbon, respectively, than those where associated plants are dominated by oil palm (Model P) and a mixture of plant types (forest species mixed with oil palm plants, or Model FP). Associated plants inside cocoa agroforests also play additional roles to support livelihoods such as health care, household consumption and timber. Therefore, beyond carbon storage, cocoa agroforest is an important reservoir of some local species and thus useful for biodiversity conservation and local livelihoods. As cocoa agroforests in DRC are recognized as one of the main responses to climate change, this study constitutes an early contribution to the process of reducing emissions from deforestation and forest degradation (REDD +) in forest landscapes in this country of the Congo Basin.
... In the Ecuadorian Amazon, the SOCstock varies at a depth of 30 cm as follows: 49.44 t ha −1 in agroforestry systems and 36.75 t ha −1 in Dali Grass without three [Bravo, 2017, Jadan et al., 2015. At a 10 cm depth in cacao cultivation areas, the agroforestry system can reach 69 t ha −1 . ...
Thesis
Soil is a global resource that has the capacity to contain large amounts of organic carbon. In fact, soils contain more carbon than plants and the atmosphere combined. However, in recent decades human activities such as land-use change, deforestation, biomass burning, and environmental pollution have accelerated the release of terrestrial carbon into the atmosphere, increasing the greenhouse effect. The study of soil organic carbon cycle was recognized in the last decades as a necessary step for controlling future increases in atmospheric CO2, as well as necessary to simultaneously ensure the sustainability agricultural activities. A better comprehension of the he dynamics of soil organic carbon (SOC) in different agricultural systems will allow an improvement of soil quality and soil organic carbon storage under different climate and soil conditions. However, despite of decade’s long research on this subject, there is still the need for a better appraisal of soil carbon dynamics in specific agricultural systems based on robust in field empirical studies. So, relevant contributions to a better understanding of the impact of land use on the global carbon cycle is of great importance. The present research, framed in the context of a Ph.D. specialization on soil carbon in agricultural areas, is aimed to generate new information on the effect of different factors (climate, land use, management, altitude, and soil type) that influence the sequestration and accumulation of organic carbon along the profile in the soil in different agricultural and forest systems across contrasting edaphoclimatic conditions. This research includes not only new quantitative information on soil organic carbon, but also innovative studies on its distribution among different soil carbon compartments and on the use of near infrared spectroscopy (NIR) on soil organic carbon determination. The first study (Chapter 2) is an analysis of the effect of different agricultural uses in a subtropical climate, in the area of the Carrizal River valley in the province of Manabí Ecuador, based on the analysis of 64 soil profiles. In each profile samples were taken in the soil profile horizons to obtain the concentration of organic carbon up to a maximum depth of 150 cm in different agricultural management (permanent, intensive rotation and abandoned crops), In this study twenty-one different agricultural uses were identified. As expected, the highest concentrations of soil organic carbon happened in the A horizon, which has an average thickness of 40 cm. A trend towards a higher carbon sequestration potential was observed in the grass, intercropping like cocoa with banana and corn area management with an average value of 1.7% C, much higher than the area under mechanized agriculture, which presented lower carbon concentration, with an average value of 0.26% C. Regarding the total soil organic carbon stock, the first horizon accumulated more carbon compared to the other (B and C) soil profiles, with an average value of 41.32±20.97 t C ha-1 and 15.06±15.61 t C ha-1, respectively. The second study (Chapter 3) evaluated the effect of forest management in a temperate climate. For this study, soil samples were taken in a managed environment of forest species (Alnus incana, Fagus sylvatica, Picea abies and Mixed: stands containing beech} and spruce) in an elevation range from <900 m a.s.l. to >1100 m a.s.l. from the Babia Góra National Park in southern Poland. Sampling points were taken up to a maximum depth of 100 cm. The results in this study revealed that the SOC reserves in the mountain soils of the Babi Góra National Park are characterized by their great variability (from 50.10 t ha-1 to 905.20 t ha-1). In the conditions of this study, the type of soil is the dominant factor determining soil organic carbon stock, which coupled with topographic factors influence soil and vegetation conditions. This explains such diversity in the accumulation of soil organic carbon in different mountain soils in the areas. The largest carbon stock was recorded in histosols (>550 t C ha-1), which are located in the lower part of the national park. The third block of the research focused on two field studies in one of the most important agroforestry systems across the Mediterranean, dehesa. The first study (Chapter 4) is located in a dehesa in Hinojosa del Duque in Córdoba, Spain: Dehesa is an agro-silvo-pastoral system which combines open land and low density trees (holm oaks). In this first study we investigated two adjacent dehesas on the same soil type but different characteristics. One was a pastureland with young holm oaks (planted in 1995 with a density of 70 trees ha-1 at 12 m x 12 m spacing. The area had been grazed by Merino sheep since 2000, at a grazing rate of 3 sheep per hectare. The second, adjacent area is a cultivated pasture with mature oaks with a minimum age of 90-100 years widely spaced (1.2 trees ha-1). Every three years, a mixture of peas and oats is grown for hay. Tillage is used for the preparation of this seeding except in the immediate vicinity (about 0.3-0.4 m) of the tree trunk. The first dehesa at higher tree density was part of this second dehesa, and so both had the same characteristics until year 1995. Both dehesas were sampled simultaneously in 2017. Sampling points were taken under and outside the canopy projection up to a maximum depth of 100 cm divided into 8 sections (0-2 cm, 2-5 cm, 5-10 cm, 10-20 cm, 20-40 cm, 40-60 cm, 60-80 cm, and 80- 100 cm). The results showed that a change in dehesa type from an old low density dehesa combining pasture with seeding every 3 years to a one only pastured with increased tree growth (70 trees ha), showed no significant differences in carbon concentration after 22 years’ since implanting the more dense dehesa. A clear stratification of carbon was observed in the soil profile, particularly in the top 10 cm of the soil, as well as an effect of the adult tree which resulted in a higher concentration under the tree canopy in the middle soil depth section (20-40 cm) in the mature dehesa. Significant difference in carbon stock was only observed in the top 0-2 cm (5.86±0.56 t ha-1 vs 3.24±0.37 t ha-1, been higher in the newly planted dehesa. To our knowledge this is the first study evaluating in dehesa the distribution of soil organic carbon into this four (unprotected and physically, chemically and biochemically protected) fractions. Our results showed how most of the carbon in the two dehesas was stored in the unprotected fraction, been its relative contribution higher in the top 0-2 cm o the pastured dehesa and in the below canopy area of the mature trees in the cropped dehesa. This indicates that much of the fraction contained in these soils is particularly vulnerable to hypothetical changes to less sustainable managements. The second study in dehesa (Chapter 5) was located in the municipality of Pozoblanco in the north of the province of Córdoba. In this area three areas of continuous extensive grazing for more than 50 years with cattle, sheep, and pigs were identified, and three areas with different intensity were studied. These areas were: I) Intensive grazing management. II) moderate grazing management and III) no grazing (area excluded for more than 20 years). Sampling points were taken at each of the three areas up to a maximum depth of 30 cm divided into 5 sections (0-2 cm, 2-5 cm, 5-10 cm, 10-20 cm, and 20-30 cm). Concentrations at different grazing intensities showed, as expected, higher carbon concentrations at the surface soil layer (0-2 cm) average of 1.59±0.44%, decreasing to 0.48±0.15% in the deeper section of the soil profile at 20-30 cm. Contradicting our initial hypothesis, no differences in soil organic carbon concentration were detected among the three areas with different grazing intensities, The total carbon stock was analyzed in the whole soil profile (0-30 cm), indicating non significant differences among the two grazed areas, average value of 27 t ha-1, or the area without grazing 26 t ha-1. As in the previous dehesa, the dominant fraction was the unprotected carbon. However, in this case the relative differences in the soil organic carbon concentration between the unprotected fraction and the physically and the chemically protected fractions was larger than in the first dehesa, particularly because the protected fractions tended to show a higher concentration than in the dehesa studied in Chapter 4. Using the empirical results from the study of the second dehesa, we developed a spectral library and predictive equations of concentration of soil organic carbon using Vis-NIR (Chapter 6) from this dataset. The accuracy of the SOC predictive models was very good, with R2 higher than 0.95 and residual predictive deviation (RPD) higher than 4.54, respectively. Refinement of VIS-NIR techniques, such as the one discussed in Chapter 6, could increase our ability to provide more affordable and robust technologies to measure large numbers of samples with the required accuracy, although it is less clear how to address other important sources of variability, such as soil depth, soil type, bulk density, and rock content. To reduce this uncertainty will be of great relevance to continue performing detailed experiments to better quantify on the effect of land use and cropping systems on soil organic carbon content, such as those described in chapters 3, 5 and 5. To date, these experiments are irreplaceable to test specific hypothesis relevant at local level (like the time to increase soil organic carbon stock after planting at higher density, Chapter 4), but also to create a corpus of available data which could improve, or lead to new ones, conceptual or numerical simulation models that can systematize our understanding of the soil organic carbon cycle and eventually reduce the need for large-scale sampling to verify the evolution of soil organic carbon in agricultural systems.
... We measured the diversity of cocoa agroforests in the Bengamisa-Yangambi forest landscape by evaluating base on the following: (i) species diversity (species richness, Shannon-Wiener index, Piélou's evenness index, Simpson's index, rarefaction curve); (ii) relative abundance; (iii) structure (density and basal area); and (iv) linkage between density and biodiversity. Each of these parameters is generally used in the characterization of cocoa agroforest in other countries [15,40,41,[43][44][45][46][47] and for the characterization of forest stands [29,48,49]. ...
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Cocoa agroforestry has evolved into an accepted natural resource conservation strategy in the tropics. It is regularly proposed as one of the main uses for REDD+ projects (Reducing Emissions from Deforestation and forest Degradation and the role of conservation, sustainable management of forests, and enhancement of forest carbon stocks in developing countries) in the Democratic Republic of the Congo. However, few studies have characterized the cocoa agroforestry systems in this country. Hence, this research proposes to determine the impact of distance from Kisangani (the unique city in the landscape) and land-use intensity on the floristic composition of cocoa agroforests in Bengamisa-Yangambi forest landscape in the Congo Basin. The results revealed that species diversity and density of plants associated with cocoa are influenced by the distance from Kisangani (the main city in the landscape and province). Farmers maintain/introduce trees that play one or more of several roles. They may host caterpillars, provide food, medicine, or timber, or deliver other functions such as providing shade to the cocoa tree. Farmers maintain plants with edible products (mainly oil palms) in their agroforests more than other plants. Thus, these agroforests play key roles in conserving the floristic diversity of degraded areas. As cocoa agroforestry has greater potential for production, biodiversity conservation, and environmental protection, it should be used to slow down or even stop deforestation and forest degradation.
... Regarding the impact of selective thinning on functional diversity, we highlight the work carried out by de Avila et al. [19], and on the structure of the forest, the work of Yguel et al. [20]; both works conclude on the importance of assessing thinning and the impact it has on the forest's richness. Existing forestry studies generally focus on documentation of timber species and their production [21], on the yield of agroforestry plantations [22], on reforestation methods with native or exotic species [23,24], as well as on payment schemes for forest ecosystem services [25][26][27][28]. Furthermore, information respective to the effects of tree removal in natural tropical forest stands, in terms of richness and diversity, is still scarce. ...
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Background: The impact of selective thinning on forest diversity has been extensively studied in temperate and boreal regions. However, in the tropics, knowledge is still poor regarding the impacts of this silvicultural treatment on functional diversity, especially in tropical mountain forests, which are considered to be highly biodiverse ecosystems and also endangered by human activities. By evaluating the changes on functional diversity by using different indicators, hypothesizing that selective thinning significantly affects (directly or indirectly) tropical mountain forests, this work promotes sustainable ecosystem use. Methods: A total of 52 permanent plots of 2500 m2 each were installed in a primary mountain forest in the San Francisco Biological Reserve to assess the impact of this silvicultural treatment. Selective thinning can be defined as a controlled process, in which trees that compete with ecologically and/or valuable timber species are progressively removed to stimulate the development of profitable ones, called potential crop trees (PCT). In doing so, the best specimens remain in the forest stand until their final harvest. After PCT selection, 30 plots were chosen for the intervention, while 22 plots served as control plots. The thinning intensity fluctuated between 4 and 56 trees ha−1 (average 18.8 ± 12.1 stems ha−1). Functional Diversity (FD) indices, including the community weighted mean (CWM), were determined based on six traits using the FD package implemented in R software. The difference between initial and final conditions of functional richness (FRic), functional divergence (FDiv), functional evenness (FEve), functional dispersion (FDis), and Rao quadratic entropy (RaoQ) was modeled using linear mixed models (LMM). As fixed factors, we used all the predictors inherent to structural and ecological forest conditions before and after the selective thinning and as a random variable, we used the membership to nested sampling units. Results: Functional Richness (FRic) showed significant changes after selective thinning, the other indexes (FEve, FDis, FDiv, RaoQ) were only influenced by predictors related to ecological conditions and characteristics of the community.
... especially in cases 1W and 2W and of similar dynamics in the Atmosphere theme. In case 1W of Tobeta Indigenous Community, its classification is limited in the subject of Biodiversity and can be considered by the number of species existing in the productive system compared to an agroforestry system of the Kichwa nationality where there is a lush number of species [58], [59], [60], but it is essential to mention that the 1W case has the area of greatest sustainability surface in relation to its peers evaluated ( Table 3). The issues of Animal Welfare and Investment in all three cases are considered as Limited, since culturally the raising of animals in the Waorani nationality is not within their ancestral cultural dynamics despite a possession of minor species and the investment is minimal due to the influence of additional income that promotes greater family or individual welfare as paid work. ...
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The Yasuni Biosphere Reserve (YBR) occupies a unique biogeographic position in the world, where the richness of the four taxa (amphibians, birds, mammals and vascular plants) reaches maximum diversity. However, threats to species conservation are latent: the opening of roads, illegal logging, the advance of the agricultural frontier, oil extraction and the trade of wild meat in the western sector of the reserve. This paper aims to evaluate the sustainability of natural resources in multicultural communities: 1) Waorani Indigenous and 2) Migrant settlers, settled in the Diversity and Life Strip (DLS) in the YBR. Three households were defined per community, selected from the snowball sampling method. Thus, three methodological processes were applied: 1) Sustainability of natural resources using the SAFA program (version 2.4.1), it has four dimensions Good Governance (GG), Environmental Integrity (EI), Economic Resilience (ER) and Social Welfare (SW); 2) Direct observation; and 3) Lacing algorithm with the GeoGebra program used for the calculation of areas of simple polygons. The results showed that the dimension of least sustainability was ER in indigenous households and in-migrant settler households it was ER and SW. The largest sustainability area of 25,12 u 2 in the migrant settler household1, while in Waorani indigenous the worst sustainability area had a value of 18,69 u 2. The programs allow to promote a better understanding of the dynamics of the sustainability of natural resources. The issues identified as limited in the communities are a priority to improve sustainability.
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Con base en la composición florística y en aspectos de la estructura (área basal y número de individuos), se caracterizó la vegetación en sistemas agroforestales (SAF) ubicados en 47 plantaciones con cacao (Theobroma cacao) en el departamento del Huila, Colombia. La vegetación en dichos sistemas estaba dominada por las especies Pseudosamanea guachapele, Musa paradisiaca, Erythrina poeppigiana, Gmelina arborea, Psidium guajava, Manguifera indica y Cordia alliodora. Las especies aracterísticas-dominantes a nivel regional fueron Gliricidia sepium, Cordia alliodora, Amyris pinnata y Persea americana. Los sistemas agroforestales con mayor riqueza fueron el de Pseudosamanea guachapele, con 36 especies y el de Musa paradisiaca, con 25. La altura de los individuos oscilaba entre 3 y 21 m, y el mayor valor se presentó en el sistema de P. guachapele; el área basal fue 64,30 m2, los mayores valores se registraron en los sistemas agroforestales de P. guachapele, con 16.41 m2 y en el de E. poeppigiana, con 18,03 m2. La participación de T. cacao a nivel regional en el área basal es de 56,63 m2 y el número total de individuos es de 4.808. En los sitios con exposición libre (cultivo limpio en 11.000 m2) la altura promedio de los individuos de cacao era de 3,5 m, el área basal, de 15,31 m2, con 1.101 individuos. Esta cantidad es casi igual a la que se encontraría en un área de igual extensión en el sistema agroforestal bajo sombra de P. guachapele (1.386 individuos) y cinco veces mayor que aquel con presencia de todas las especies asociadas pero sin T. cacao (217 individuos). Aparte de la cosecha de cacao, estos sistemas ofrecen madera, frutos y leña, y proveen servicios ecosistémicos relacionados con la protección del suelo y la conservación de la biodiversidad.
Article
Smallholder livelihoods and the restoration of tropical forests are intimately intertwined. To address the question of how reforestation affects livelihoods and how they in turn affect reforestation, a meta-synthesis was undertaken of 339 scientific publications identified from a systematic literature search. This study is focused on smallholders in the humid tropics, and uses the Sustainable Livelihoods Framework, which was developed by the UK Department for International Development as the framework for analysis. The links between reforestation and livelihoods are found to be diverse and highly interconnected. Reforestation is only one of a smallholder’s activities and typically forms part of a mosaic of land uses across a landscape. Therefore, reforestation should be designed, managed and evaluated under the perspective of a diverse livelihood portfolio, and not as a single activity isolated from other portfolio components, especially under current landscape approaches. It is important for reforestation to be a complementary rather than a competitive livelihood activity. Reforestation has great potential to address poverty, and to increase smallholder socio-ecological resilience and local social equity. However, reforestation outcomes are often suboptimal. Assessing smallholder capacity and the surrounding environment prior to reforestation, and addressing limiting local capacities and conditions in a timely manner, may enhance the likelihood of optimal benefits.
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Los distintos manejos de los suelos afectan las existencias de C del suelo. El análisis multivariado de la modelación de los stocks de C del suelo (SOC0-T), las tasas de pérdidas (-ΔC) y/o ganancias de C del suelo (ΔC), las emisiones de gases de efecto invernadero (GEI) y remociones (-GEI) de CO2 atmosférico asociadas con algunas propiedades fisicoquímicas de los suelos en sistemas productivos de la Altillanura y otros de Piedemonte de la Orinoquia conformaron tres grupos bien definidos. El clúster I agrupó a pasturas mejoradas de Granada (S1) y sistemas agroforestales (SAFs) de café asociados con plátano y leguminosas de Villavicencio (S9), donde las ganancias de C (ΔC) y absorciones de CO2 atmosférico (-GEI) fueron medias variando de ≈ 0.11 a 2.37 t C ha-1 año-1 y de -1.60 a -8.70 t CO2eq ha-1 año-1; siendo que monocultivos en rotación también formaron parte de este grupo; el clúster II reunió a monocultivos de arroz de Villavicencio (S10) y de piña de Puerto López (S14) que presentaron las más altas pérdidas de C (-ΔC) del suelo y emisiones de CO2 atmosférico (GEI) de ≈ -2.08 a -2.35 t C ha-1 año-1 y de ≈ 7.62 a 8.62 t CO2eq ha-1 año-1; el clúster III agrupo a sistemas agroforestales SAFs de caucho y leguminosas de cobertura (S13) y sistemas silvopastoriles (SSPs) de Acacia mangium y pasturas mejoradas (S12) de Puerto López con las más altas ganancias de C del suelo (ΔC) y absorciones de CO2 atmosférico (-GEI) de ≈ 0.373 a 2.64 t C ha-1 año-1 y de ≈ -1.36 a -9.67 t CO2eq ha-1 año-1. Los sistemas agroforestales son una buena alternativa para el secuestro de C del suelo en la Altillanura Plana de Colombia.
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The cocoa tree (Theobroma cacao L.) is cultivated typically in agroforestry systems in close association with a rich list of tree species and other useful plants on the same plot. Cocoa based agroforestry systems are credited for stocking significant amounts of carbon and hence have the potential to mitigate climate change. Since cocoa yields decrease non-linearly with increasing shade, a need is to design optimal cocoa agroforestry systems with high yields and high carbon stocks. We estimated the carbon stocked in a network of 229 permanent sample plots in cacao-based agroforestry systems and natural forests in five Central American countries. Carbon stocks were fractioned by both system compartments (aboveground, roots, soil, litter, dead wood – fine and coarse, and total) and tree use/form (cocoa, timber, fruit, bananas, shade and ornamentals, and palms). Cocoa plantations were assigned to a five-class typology and tested for independence with growing region using contingency analysis. Most Central American cocoa plantations had mixed or productive shade canopies. Only 4% of cocoa plantations were full sun or rustic (cocoa under thinned natural forest). Cocoa tree density was low (548 ± 192 trees ha−1). Total carbon (soil + biomass + dead biomass) was 117 ± 47 Mg ha−1, with 51 Mg ha−1 in the soil and 49 Mg ha−1 (42% of total carbon) in aboveground biomass (cocoa and canopy trees). Cocoa trees accumulated 9 Mg C ha−1 (18% of carbon in aboveground biomass). Timber and fruit trees stored 65% of aboveground carbon. The annual rate of accumulation of carbon in aboveground biomass ranged between 1.3 and 2.6 Mg C ha−1 y−1. Trade-offs between carbon levels and yields were explored qualitatively using functional relationships documented in the scientific and technical literature, and expert knowledge. We argue that it is possible to design cocoa-based AFS with good yields (cocoa and shade canopy) and high carbon stock levels. The botanical composition of the shade canopy provides a large set of morphological and functional traits that can be used to optimize shade canopy design. Our results offer Central American cocoa producers a rigorous estimate of carbon stocks in their cocoa plantations. This knowledge may help them to certify and sell their cocoa, timber, fruits and other goods to niche markets with good prices. Our results will also assist governments and the private sector in (i) designing better legal, institutional and policy frameworks, local and national, promoting an agriculture with trees and (ii) contributing to the development of the national monitoring, reporting and verification systems required by the international community to access funding and payment for ecosystem services.
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In the humid tropics, the rapid rate of deforestation has resulted in a race to protect remaining forest patches that are increasingly isolated within a rapidly expanding agricultural matrix. In these landscapes, a significant area consists of complex agro-forestry systems with high structural and functional plant diversity, providing critical resources for biodiversity conservation, such as food and habitat. Although not a substitute for natural forests, these anthropogenic habitats are gaining increasing conservation value as deforestation progresses. Shaded tree crops, such as cocoa, provide habitats for numerous forest dependent species of high conservation value and play a largely undocumented role in providing other ecological services. Following previous work on the botanical composition and structural complexity of cocoa agroforests in Talamanca (Costa Rica), we assessed if differences in the vegetation composition and structure of 36 cocoa agroforests could affect the wild diversity of small mammals, amphibians, reptiles, soil and litter macro-invertebrates and epiphytes found on cocoa trees and associated plants. Results show that Alpha-diversity is not affected by changes in vegetation structure and composition, except for amphibians and epiphytes found on cocoa trees. However, five taxa among eight showed distinct species composition patterns when compared among cocoa-based agroforestry clusters and with forest control. We showed that beta-diversity assessment enhances our understanding of the effect of management intensification on species composition and on habitat quality. The proper design of the shade component in these AFS will certainly play a key role in segregating wild species hosted in these systems and will open a new field of research for the intensification of both cocoa and associated productions in these highly diverse systems.
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This chapter presents the contribution of “chakra,” a traditional agroforestry system, to climate change adaptation and biodiversity conservation in Ecuador’s Amazonian communities. IPCC’s methodology was used for the estimation of carbon sequestration in soil, biomass, and cacao plantations. Carbon levels in multiple systems of land use were measured through temporary plots. Chakra is efficient to adapt to climate change due to higher levels of carbon sequestration and tree diversity in comparison to other forms of land use. Chakra allows for sustainable use of forests by combining cultivation of the Ecuadorian finest aromatic cacao, controlled timber extraction, production of staple food, and conservation of medicinal plants. Chakra enables Amazonian communities to contribute to both food security and well-being and conservation of the region’s high biodiversity. The chapter informs policy makers and communities about the importance of strengthening traditional agroforestry to achieve environmental and social sustainability. The Amazon region is a vulnerable ecosystem, where adaptation to climate change depends on the extent to which the options for land use are compatible with the conservation of biodiversity and the provision of the ecosystem services that sustain local communities’ livelihoods. The chapter provides solid evidence that this might be possible through traditional agroforestry.
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This chapter argues for a broader conceptual domain provided by agroforestry practices as a key pathway for the reorientation of agricultural systems in the Amazon toward modes of production that combine productivity and sustainability. A contextualization of the multiple expressions of current agroforestry development in the Amazon shows that, contrasting with homegardens and shifting cultivation, ubiquitous in the region, planned or organized agroforestry systems are still minor elements of the agricultural landscape, often arising from farmers’ experimentation or resulting from initiatives funded by international cooperation. A “multichain” approach focusing on both established markets as well as “secondary chains” is suggested as a pathway for agroforestry to go beyond subsistence toward income generation and to reduce the constraints faced by Amazon farmers to intensify land use. The costs and risks presented by practices leading to intensification, aggravated by problems in regional infrastructure, limited access to adequate technical and financial services, and insecure land tenure require equitable development policies and programs to support such initiatives. A stronger policy identity for agroforestry in the region should thus recognize the provision of both economic goods and ecosystem services, and this chapter argues that given the carbon stored in agroforestry systems, the framework of environmental international agreements is an opportunity to combine environmental and livelihood benefits through the design, promotion, and dissemination of agroforestry strategies. A review of policies that can influence adoption of sustainable land use systems in the Amazon region attests their operation in a fragmented manner. These policies must be set as a cohesive whole, being agroforestry the common thread to support and link initiatives to reduce poverty and hunger, curb deforestation and CO2 emissions, and to mitigate climate change. Agroforestry will be then an effective strategy to bridge gaps between policies, and particularly in linking environmental opportunities with economic realities, while enhancing the livelihoods of smallholders, traditional communities, and indigenous peoples in the Amazon.
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Climate change and biodiversity loss can be addressed simultaneously by well-planned conservation policies, but this requires information on the alignment of co-benefits under different management actions. One option is to allow forests to naturally regenerate on marginal agricultural land: a key question is whether this approach will deliver environmental co-benefits in an economically viable manner. Here we report on a survey of carbon stocks, biodiversity and economic values from one of the world’s most endemic-rich and threatened ecosystems: the western Andes of Colombia. We show that naturally regenerating secondary forests accumulate significant carbon stocks within 30 years, and support biodiverse communities including many species at risk of extinction. Cattle farming, the principal land use in the region, provides minimal economic returns to local communities, making forest regeneration a viable option despite weak global carbon markets. Efforts to promote natural forest regeneration in the tropical Andes could therefore provide globally significant carbon and biodiversity co-benefits at minimal cost.
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Este artículo propone una metodología para un Sistema de Pago por Servicios Ambientales en el Estado de México, fundamentado en principios de sustentabilidad ambiental, manejo novedoso de recursos naturales y políticas ambientales dirigidas a proteger los ecosistemas y contribuir al crecimiento económico local.
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The carbon, phosphorus, and water cycles of a subtropical floodplain forest, and related ecosystem characteristics, were studied. Located at 750 m elevation in Puerto Rico (latitude 18@?N) the forest had 27 tree species, 3059 stems/ha, a basal area of 42.4 m^2/ha, maximum height of 17 m, and a leaf area index of 3.3. Palm (Prestoea montana) dominated the forest, and, with two other species, accounted for 68% of the dominance. Throughfall, stemflow, interception, runoff, transpiration, and evapotranspiration accounted for 81.6, 9.8, 8.6, 77.7, 13.7, and 22.3% of annual rainfall (3725 mm) respectively. The stand carbon storage was 28.77 kg/m^2, distributed as follows: aboveground 35.4%, vegetation 44.2%, soil to 1 m depth 55%, palms 10.9%. Vegetation biomass was partitioned as follows: leaves 9.8% (75% are palm leaves), wood 68%, and roots 21.8%. Net aboveground primary carbon productivity (NPP) was 876 g@?m^-^2@?yr^-^1. Average litterfall was 2.4 g@?m^-^2@?d^-^1 (palm leaves 32%, other leaves 39%, and wood 10%). Half-lives of decaying material were 188, 306, 462, and 576 d, respectively, for palm leaves still attached to the parent tree, dicotyledonous leaves, palm leaves on the ground, and palm trunks. Total organic carbon concentrations in stream water increased with increasing stream discharge (from 2 g/m^3 to 30 g/m^3). Watershed export of carbon was 50 g@?m^-^2@?yr^-^1 (including 12 g@?m^-^2@?yr^-^1 in the form of leaf litter). Mean P concentration in palm leaves (1.18 mg/g) was twice that in dicotyledonous leaves (0.64 mg/g). Compared to a rainfall phosphorus input to the watershed of 63 mg@?m^-^2@?yr^-^1, leaching from the canopy was high (167 mg@?m^-^2@?yr^-^1), as was the loss of P from the watershed (611 mg@?m^-^2@?yr^-^1). Phosphorus-conserving mechanisms included a high rate of retranslocation in palms (504 mg@?m^-^2@?yr^-^1). In spite of these mechanisms, there was a net P loss from the watershed that ranged from 136 to 544 mg@?m^-^2@?yr^-^1. Periodic flooding, poor soil aeration, intensive year-round rainfall, and low atmospheric saturation vapor pressure deficits are believed to be the main driving forces of the floodplain forest, which exhibits many characteristics typical of lowland rain forests and floodplain wetlands. Rates of NPP, litterfall, and biomass turnover (residence time of 14-17 yr) are faster than expected for the climatic conditions, whereas rates of wood production and storage of organic matter in the vegetation and soil profile are lower than expected for the climate.