The role of rustic coffee plantations in the conservation of wild tree diversity in the Chinantec region of Mexico

Abstract

Rustic coffee plantations are characterised by the use of numerous wild and cultivated tree species for providing shade to the coffee shrubs. This paper analyses the role of these plantations in wild tree conservation through the examination of their patterns of floristic variation in southern Mexico. The studied plantations included a total of 45 plant species, most of which were wild tree species, including both mature forest and pioneer taxa. An extrapolation of the species accumulation curve among stands indicated that the whole system, composed of more than 100 coffee plantations, may harbour as many as 34 species of wild trees. The floristic structure of rustic coffee plantations was highly variable. This variation is a result of a combination of factors such as human management, original stand cover and the asynchrony in development stage of different plantations. This promotes a large -diversity in the system. Thus, although a single plantation may have a limited potential to preserve wild tree species, it is the whole ensemble of floristically heterogeneous plantations which renders this agroforestry system valuable for plant diversity conservation, particularly in a region where native forest vegetation has almost disappeared.

Full text

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The role of rustic coffee plantations in the
conservation of wild tree diversity in the Chinantec
region of Mexico
FA
´BIO P. BANDEIRA
1,2
, CARLOS MARTORELL
3
,
JORGE A. MEAVE
3
and JAVIER CABALLERO
2,*
1
Depto. de Cie
ˆncias Biolo
´gicas, Universidade Estadual de Feira de Santana, Brazil;
2
Jardı´n Bota
´nico,
Instituto de Biologı´a, Universidad Nacional Auto
´noma de Me
´xico, Apartado Postal 70-614, Me
´xico
DF 04510, Mexico;
3
Facultad de Ciencias, UNAM, Mexico DF; *Author for correspondence (e-mail:
jcnieto@servidor.unam.mx; fax: +52-55-5622-9046)
Received 13 February 2003; accepted in revised form 12 January 2004
Key words: Alfa diversity, Beta diversity, Chinantec, Coffee cultivation, Ethnoecology, In situ
conservation, Mexico
Abstract. Rustic coffee plantations are characterised by the use of numerous wild and cultivated
tree species for providing shade to the coffee shrubs. This paper analyses the role of these plan-
tations in wild tree conservation through the examination of their patterns of floristic variation in
southern Mexico. The studied plantations included a total of 45 plant species, most of which were
wild tree species, including both mature forest and pioneer taxa. An extrapolation of the species
accumulation curve among stands indicated that the whole system, composed of more than 100
coffee plantations, may harbour as many as 34 species of wild trees. The floristic structure of rustic
coffee plantations was highly variable. This variation is a result of a combination of factors such as
human management, original stand cover and the asynchrony in development stage of different
plantations. This promotes a large b-diversity in the system. Thus, although a single plantation may
have a limited potential to preserve wild tree species, it is the whole ensemble of floristically
heterogeneous plantations which renders this agroforestry system valuable for plant diversity
conservation, particularly in a region where native forest vegetation has almost disappeared.
Introduction
Rustic coffee plantations of the indigenous areas of Mexico are an example of
complex, highly diverse and multipurpose agroforestry systems, as defined by
Nair (1989). In these systems, the understorey is occupied mainly by coffee,
while shade is provided by many useful wild and cultivated trees. The result is a
complex ‘coffee garden’ (Moguel and Toledo 1999), that provides cash income,
in addition to medicines, food, fuel and other plant products for the household
economy (Moguel and Toledo 1999; Soto-Pinto et al. 2001). According to
Moguel and Toledo (1999), by 1991 a total of 850,000 ha were devoted to
coffee cultivation in Mexico, and at least 70% of the producers worked
holdings less than 2 ha in size. During the 1970s and the 1980s, the originally
diversified shade-tree component was eliminated or substituted by a few species
of Inga (Mimosaceae) in one third of the total coffee producing area of Mexico
Biodiversity and Conservation 14: 1225–1240, 2005. Springer 2005
DOI 10.1007/s10531-004-7843-2

(Nestel 1995). Most of this area corresponds to large holdings whose owners
have incorporated the use of agrochemicals and of sun-grown varieties. In
contrast, diversified shade systems with limited or no use of agrochemicals have
persisted in the majority of the small-scale holdings of the indigenous regions
(Nestel 1995). This is the case for Oaxaca, one of the three most important
coffee-producing states of Mexico, the other two being Chiapas and Veracruz.
Coffee growing areas in Mexico are biologically important, as most of them
are located in the transitional zone between the Nearctic and the Neotropical
floristic realms (Moguel and Toledo 1999). Furthermore, the forests of these
areas are recognised by their large species richness (Rzedowski 1991). The
landscape in these regions is generally much degraded, thus rustic coffee
plantations play an important role in biodiversity conservation as they provide
suitable habitats for many species (Hansen et al. 1991; Perfecto et al. 1996; Rice
and Ward 1996), as has been documented for arthropods (Perfecto et al. 1996,
1997), birds (Aguilar-Ortiz 1982; Greenberg et al. 1997), small mammals
(Gallina et al. 1996), vertebrates in general (Rendo
´n-Rojas 1994), and orchids
and other cloud forest epiphytes (Nir 1988; Williams-Linera et al. 1995). In the
highlands of Chiapas, for example, Soto-Pinto et al. (2001) reported that 72 out
of 77 plant species growing in rustic coffee plantations are wild plants typical
both from the cloud forest and the tropical rain forest.
Despite its economic and biological importance, the floristic structure of
coffee agroforestry systems in indigenous regions, along with its spatial and
temporal variation, remains largely neglected, and except for one study (Soto-
Pinto et al. 2001), plant diversity in coffee plantations has not been system-
atically documented. This information is required to assess their potential for
plant diversity conservation. This would allow examination of questions such
as: how many and which wild plant species may grow in the rustic coffee
plantations? Are all of them equally important for biodiversity conservation?
Are coffee plantations floristically variable? If so, what is the implication of
such variability for plant diversity conservation in the coffee growing areas?
Based on the examination of the floristic composition of rustic coffee planta-
tions of a Chinantec indigenous village in Oaxaca State, this study addresses
the above questions.
Study area
This study was conducted in the village of Rancho Grande, San Juan Bautista
Valle Nacional Municipality (Oaxaca State, Mexico; Figure 1). This is a
mountainous region with a warm and humid climate. Elevation ranges from
660 to 1150 m a.s.l. The mean annual temperature is 22 C and mean annual
precipitation is about 4000 mm (Rzedowski and Palacios-Cha
´vez 1977). This is
a transitional area between the tropical lowland forest and premontane forest
in the system of Holdridge et al. (1971). Although the local landscape is highly
fragmented, this region is considered a priority conservation area by the
1226

National Commission for Biodiversity Conservation of Mexico (Arriaga et al.
2000).
Rancho Grande has 181 inhabitants, all Chinantec speakers, belonging to 38
households (INEGI 1991), most of which are involved in coffee production.
This activity is their major source of cash income. The total coffee growing area
is about 230 ha (Table 1), with each household maintaining on average three
plantations. Most coffee plantations are located near the village and readily
accessible by local roads and paths. Besides growing coffee, corn, beans and
squash are cultivated for subsistence through slash and burn procedures. Some
households cultivate vanilla (Vanilla spp.) intercropped with coffee shrubs, and
Figure 1. Location map of study area showing the Oaxaca State and Valle Nacional municipality.
Table 1. Land use and cover types at Rancho Grande, Oaxaca, Mexico.
Land use and land cover categories MP/p MS Total surface
(ha) (ha) (%)
Rustic coffee plantations 3 2.1 229.77 56.9
Corn fields (milpas) – 0.3 11.30 2.8
Early and late vegetation growth 0.8 2.3 102.54 25.4
Protected areas of mature forest* – – 60.00 14.8
MP/p – mean number of parcels per producer; MS – mean surface.
* In this category are included the communal reserve and other areas protected because of their
high risk.
1227

ixtle (Aechmea magdalenae) under the canopy of secondary growth. These two
crops are grown for commercial purposes. Another relevant activity is the
extraction of timber species such as Cedrela odorata and Cordia alliodora.
These species are managed in the rustic coffee systems. Cattle raising was an
important economic activity in the 1980s, but it has since been almost replaced
by coffee cultivation. The combination of these land use forms by the Chi-
nantec of Rancho Grande has produced a heterogeneous landscape composed
of small patches of corn fields, coffee plantations, home gardens, fallow fields,
secondary and mature forests.
Coffee plantations in Rancho Grande are dynamic systems with an effective
life of around 20–40 years. Three stages may be distinguished during a plan-
tation life cycle: establishment, development, and decline. Initially, the plan-
tation is established in a mature or secondary forest patch, although
occasionally, an abandoned former coffee plantation may be used to establish
the new one. Before introducing the coffee plants, most shrubs, small trees and
herbs are eliminated; in contrast, the majority of trees and useful plants, such
as C. alliodora,Inga latibracteata,andChamaedorea tepejilote, are spared.
During the development stage of the plantation, which lasts up to 20 years,
farmers continue to eliminate wild shade trees, and gradually replace them by
cultivated useful species. Although many incoming pioneer species are con-
stantly eliminated from the plantation, some are allowed to establish or are
even promoted. The two most notorious examples of wild trees managed in
coffee plantations are I. latibracteata and C. alliodora. The declining stage is
characterised by a significant decrease in coffee production, although coffee
may still be harvested for a few more years. Once harvesting is no longer
profitable and depending on market value for coffee, cultivators may either
abandon the plantation, renew the plantation by replacing old coffee shrubs
with new ones and eliminating some shade trees, or convert the plantation into
a corn field, grassland or fruit tree plantation.
Methods
Data collection
A census of all coffee plantations in use at Rancho Grande was carried out.
They were numbered for selecting 22 of them at random in order to assess
their species composition and the relative abundances of shrub and tree
species. The selected sample included a wide range of elevations, sizes and
ages of development (Table 2). Each coffee plantation was sampled by means
of parallel transects following the method used by Gentry (1982), as modified
by Romero-Romero et al. (2000) for the study of small patches of secondary
montane forests. A total of ten 25 ·4 m transects were established in each
coffee plantation, with a minimum distance of 5 m between them. In addition
to the 22 coffee plantations, one patch of natural vegetation, representing a
1228

100-year-old forest, was also sampled with a 0.1 ha plot (40 ·25 m) located
at its center.
All trees with a diameter at breast height ‡2.5 cm, along with useful shrubs
and herbs indicated by the plantation owner were recorded. Ferns, epiphytes
and cacti were excluded. Botanical specimens were collected for each species
encountered. They were taxonomically identified using local checklists (Martin
1996; Romero-Romero et al. 2000) and reference herbarium material deposited
at the National Herbarium of the Universidad Nacional Auto
´noma de Me
´xico
(MEXU); vouchers under Fa
´bio Bandeira’s collection number were also
deposited at MEXU.
The owners of the 22 sampled coffee plantations were interviewed in order to
obtain land use history and socio-economic information for each one, as well
as the use and management of the plant species found in the plantations.
Data analysis
The sampled coffee plantations were subjected to a correspondence analysis
(CA) (Reyment and Jo
¨reskoj 1996; Rohlf 1997) in order to assess their
floristic variability. Two ordinations were performed, one using binary
Table 2. Characteristics of the rustic coffee systems sampled at Rancho Grande.
Coffee
plantation
Elevation
(m a.s.l.)
Area
(ha)
Age
(years)
Previous
land cover
a
No. of individuals
per 0.1 ha
Number of species
per 0.1 ha
1 681 2 22 Early 61 15
2 660 1.75 16 Early 13 4
3 703 3 30 Late 55 9
4 706 2 25 Late 42 19
5 668 2 15 Early 15 4
6 724 1.5 17 Early 40 13
7 726 5 34 Late 50 6
8 740 3 9 Early 49 16
9 681 1.7 20 Early 24 4
10 766 5 7 Early 27 10
11 750 1.7 35 Late 36 10
12 843 1.25 20 Late 52 9
13 875 1 4 Early 52 9
14 900 2 19 Late 58 14
15 906 1 20 Late 23 6
16 901 1 8 Late 31 11
17 905 3 10 Early 24 5
18 917 1 20 Early 28 5
19 928 2 25 Late 57 11
20 922 2 25 Late 32 9
21 922 1.5 10 Early 31 11
22 943 1 18 Early 15 5
a
Early – early secondary growth; Late – late secondary growth.
1229

(presence–absence) data, and the other based on the relative abundances of
wild tree species present in at least two plantations. We then assessed the effects
of altitude, previous land cover, parcel age, householder’s characteristics, and
their interactions on the plantations’ species richness, and on their floristic
structure, the latter expressed as the plantations’ CA scores based on the rel-
ative abundances matrix. We used a log-linear regression to analyse the rela-
tionship between the above listed factors and species richness (McCullagh and
Nelder 1983; Crawley 1993), and an ANOVA for the analysis of floristic
structure (Sokal and Rohlf 1995). The GLIM 4.0 software was used for these
analyses, and the models were simplified following Crawley’s (1993) recom-
mendations. Normality was assessed by means of a Shapiro–Wilk test in SPSS
9.0. The proportions of wild and non-native cultivated species among coffee
plantations were compared with a Gheterogeneity test (Sokal and Rohlf 1995).
The contribution of within and between-plantation variation to total wild
tree and shrub diversity conserved in coffee plantations was evaluated by cal-
culating Whittaker’s aand bcoefficients (Magurran 1988; Colwell and
Coddington 1995). A high b-diversity means that individual coffee plantations
host different species, so that the larger the number of plantations, the more
species would be protected. To estimate the total number of wild species that
the whole system of 110 coffee plantations of Rancho Grande may protect, a
mean cumulative species-richness curve for different numbers of coffee plan-
tations was obtained by generating random combinations of the 22 sampled
plantations. A two-parameter hyperbole was adjusted to these data
by applying the maximum likelihood method to the Eadie–Hofstee
transformation (Colwell and Coddington 1995).
Results
Structure of coffee plantations
In general coffee plantations of Rancho Grande are structurally complex. In
addition to coffee, they include many other plant species that provide food,
medicines, timber, firewood and other products for the household economy
and for the local market (Table 3). They include both introduced, cultivated,
and wild species under different degrees of management. Cultivated species are
either native or introduced from the Old World and from other Neotropical
regions such as orange (Citrus sinensis), cassava (Manihot esculenta), banana
(Musa acuminata ·balbisiana) and avocado (Persea americana). Useful plants
may also be encouraged in order to maximise their availability. In general,
herbs are commonly eliminated from the system as they are thought to compete
with coffee. Only culturally important annuals, such as Thalia sp. and Calathea
lutea, are tolerated, or even promoted, in coffee plantations. Pioneer species
such as C. alliodora or Inga sp. are an important element of the wild flora of
coffee plantations.
1230

Table 3. Botanical, ethnobotanical and ecological information for the species occurring in rustic coffee plantations at Rancho Grande.
Family Species Growth
form
Cultural
status
Uses Destiny RF
Acanthaceae Unidentified t TP 1, 3 I 0.14
Actinidiaceae Saurauia scabrida Hemsl. t TM 4,7 I 0.09
Anacardiaceae Mosquitoxylum jamaicense Krug & Urb. t TP 1, 3 I 0.05
Arecaceae Chamaedorea tepejilote Liebm. ex Mart. p PM 4 III 0.41
Asteraceae Unidentified s TP 3 I 0.09
Boraginaceae Cordia alliodora (Ruiz & Pav.) Oken t TP 1, 5 III 0.77
Bromeliaceae Ananas comosus (L.) Merr. h CI 3, 4 I 0.05
Caricaceae Carica papaya L. t TP – I 0.05
Cecropiaceae Cecropia obtusifolia Bertol. t TP 1 I 0.14
Euphorbiaceae Croton draco Schltdl. t TP 1, 2 I 0.09
Euphorbiaceae Manihot esculenta Crantz. h CI 4 I 0.09
Fabaceae Erythrina folkersii Krukoff & Moldenke t CN 7 I 0.09
Fabaceae Lonchocarpus sp. t TM 1, 3, 6, 7 I 0.18
Lauraceae sp. 1 (Unidentified) t TM 1, 5, 6 III 0.14
Lauraceae sp. 2 (Unidentified) t TM 1, 5, 6 III 0.05
Lauraceae Licaria capitata (Schltdl. & Cham.) Kosterm. t TM 5, 1, 6 III 0.05
Lauraceae Persea americana Mill. t CN 1, 4 I 0.18
Lauraceae Persea schiedeana Nees t PM 1,4 III 0.23
Marantaceae Calathea lutea (Aubl.) Schult. h PP 7 I 0.05
Marantaceae Calathea sp. h PPM 4 I 0.45
Marantaceae Thalia sp. h PP 4, 7 I 0.36
Meliaceae Cedrela odorata L. t PP 1, 5 III 0.41
Meliaceae Swietenia sp. t CN 1, 5 II 0.14
Mimosaceae Inga jinicuil Schltdl. & Cham. ex G. Don t CN 1, 3, 4, I 0.09
Mimosaceae Inga latibracteata Harms t PP 1, 3 I 1
Mimosaceae Inga sp. t PP 1, 3 I 0.32
Mimosaceae Leucaena diversifolia (Schldl.) Benth. subs. stenocarpa (Urban) S. Za
´rate t TP 1, 3 I 0.27
Moraceae Ficus sp. t TM 1, 3 I 0.09
1231

Table 3. (Continued)
Family Species Growth
form
Cultural
status
Uses Destiny RF
Musaceae Musa acuminata ·balbisiana h CI 3, 7 III 0.09
Myrtaceae Psidium guajava L. t TP 1, 3 I 0.18
Poaceae Saccharum officinarum L. h CI 3, 4 I 0.09
Rutacaeae Citrus aurantifolia (Christm.) Swingle t CI 3, 4 I 0.09
Rutaceae Citrus reticulata Blanco t CI 3, 4 I 0.23
Rutaceae Citrus sinensis (L.) Osbeck t CI 3 I 0.45
Sapindaceae Cupania dentata DC. t TMP 1, 3 I 0.18
Sapotaceae Chrysophyllum mexicanum Brandegee ex Standl. t TMP 7, 3 I 0.09
Sapotaceae Pouteria sapota (Jacq.) H.E. Moore & Stearn t PM 1, 3, 4, 7 III 0.27
Solanaceae Cestrum dumetorum Schltdl. s TP 1, 4 I 0.23
Sterculiaceae Theobroma cacao L. t CN 3, 4 I 0.05
Tiliaceae Heliocarpus appendiculatus Turcz. t TP 1, 7 I 0.18
Tiliaceae Heliocarpus donnellsmithii Rose t TP 1, 7 I 0.27
Tiliaceae Trichospermum mexicanum (DC.) Baill. t TP 1, 3 I 0.05
Ulmaceae Trema micrantha (L.) Blume t TP 7 I 0.27
Verbenaceae Lippia myriocephala Schltdl. & Cham. t TP 1, 3 I 0.41
Unidentified t TM 5, 1, 3 I 0.14
Growth form: t = tree; p = palm; s = shrub; h = herb. Cultural status: TP = tolerated pioneer; TM = tolerated mature forest; PM = promoted mature
forest; CI = cultivated introduced; CN = cultivated native; PP = promoted pioneer. Uses: 1 = coffee shade; 2 = medicinal; 3 = firewood; 4 = food;
5 = timber; 6 = construction; 7 = others. Destiny: I = household consumption only; II = trade in local and regional markets; III = both. RF = relative
frequency.
1232

A total of 45 species were found in the sampled plantations. More than two
thirds of them were wild species, which account for 77% of all trees recorded in
the parcels. Several of them are endemic to Mexico and at least one species
(I. latibracteata) is endemic to the studied region. Mean plant density for all life
forms (trees, shrubs, palms and useful herbs) in the coffee systems was
370.5 stems/ha (range: 130–610 stems/ha). For trees alone, mean density was
275.9 stems/ha (range: 110–510 stems/ha).
Floristic structure heterogeneity
Excluding coffee, epiphytes and those herbs periodically removed by cultiva-
tors, plantations have an average of nine species (range: 4–19, Table 2) in the
sampled area of 0.1 ha. Only two species (4.4%) occurred in most plantations:
I. latibracteata (22 plantations), and C. alliodora (17 plantations). In contrast,
37 species (82.2%), mostly wild trees, were found in less than one third of the
plantations (Figure 2).
The CA based on the binary data matrix showed no clear pattern of
floristic variation, suggesting that the shade-tree component of coffee plan-
tations is highly heterogeneous. In contrast, the CA based on the relative
abundances matrix revealed a distinct pattern. Two groups of coffee systems
were distinguished along the first axis, each comprising 11 coffee plantations
(Figure 3). Plantations with low CA scores have a higher relative abundance
of C. alliodora while those having large scores have higher relative abundance
of I. latibracteata. The other 25 species present in the parcels had low
Figure 2. Relative frequency (%) of species occurring in 22 rustic coffee plantations.
1233

abundances and did not contribute significantly to the distinction between the
two groups.
The regression analyses showed that variation in species richness and floristic
structure (the latter defined as the relative abundance-based CA score for each
plantation) is neither related to elevation nor to technological and socio-eco-
nomic differences between coffee producers. The floristic structure of shade
trees was only significantly influenced by the interaction between plantation
age and the existing forest cover type before the establishment of the plantation
(F=6.224, p=0.022). CA scores for plantations established in late secondary-
growth decreased significantly with plantation age, whilst those of plantations
established in early secondary-growth showed no significant change. The mean
floristic structure of both kinds of plantations converges around the twentieth
year (Figure 4). Residuals were normal (Shapiro–Wilk=0.948, p=0.375).
The role of coffee plantations in biodiversity conservation
Rustic coffee plantations harbour a considerable number of wild tree species.
The plantations include significantly more wild (27) than cultivated (12) plant
species (G
Goodness of fit
=214.09, df=2, p< 0.0001), but there were no differ-
ences in the proportions of wild and cultivated species among plantations
(G
Heterogeneity
=40.12, df=42, p=0.553). Thirteen wild tree species grow
Figure 3. CA ordination of 22 coffee plantations (P) and species (S) based on a relative abundance
matrix for wild tree species.
1234

exclusively in mature forest; the remaining are pioneer plants frequent in
secondary vegetation, albeit they may also occur in mature stands.
Variability in pioneer species composition is lower, as their overall frequency
is higher throughout all plantations. Thus, a-diversity is higher for pioneer
species (3.5 species/plantation) and lower for mature forest trees (2.2 species).
The opposite was found for b-diversity (3.3 and 4.9, respectively). The number
of species predicted for the whole study area by the two-parameter hyperbole is
very similar for both groups (18 pioneers; 16 mature forest species). Pioneer
species richness grows more rapidly than that of mature forest species with
increasing number of plantations (Figure 5), implying that more area would be
required to maintain the same number of mature forest species. The potential
number of wild tree species (34) in all 110 coffee plantations of Rancho Grande
is virtually identical to the number recorded in the 0.1 ha plot of mature forest
sampled in this study (35 species; Table 4). However, this similarity contrasts
with the fact that the number of species shared by the two systems is very small,
as only six species occurred in both of them: Saurauia scabrida,Lonchocarpus
sp., Licaria capitata,Persea schiedeana,Chrysophyllum mexicanum and
Heliocarpus sp.
Discussion
A comparison of our results with those derived from a study conducted in a
coffee growing area in northern Chiapas, Mexico (Soto-Pinto et al. 2001) showed
that the general patterns of floristic structure observed at Rancho Grande may
be generalised, despite some notable differences. More than two thirds of the
plant species and most trees at Rancho Grande’s coffee plantations were wild
Figure 4. Effect of age on the floristic structure of plantations established on early (—r—) and
late (- - - u- - -) secondary growth. Y-axis values are the score for each coffee plantation in the first
CA axis based on the relative abundance matrix for wild species.
1235

plants, while in Chiapas 90% of the 77 recorded woody species were native. The
average tree density found in this study (275.9 trees/ha; range: 110–510) was
somewhat lower than in Chiapas (371.4 trees/ha; range 100–800). Contrastingly,
frequency distributions of species encountered at both locations were very
similar, with less than 10% of the species being common to most plantations, and
over 80% of the species occurring in only one or few plantations. This pattern is
confirmed by the large heterogeneity revealed by the CA.
The floristic structure of plantations appears to be affected by cultural fac-
tors. This is well illustrated by the two most common trees in plantations,
namely I. latibracteata and C. alliodora. The former has been an element of
utmost importance in Mesoamerican agroforestry systems since pre-Hispanic
times, when it served as a tutor tree in cocoa (Theobroma cacao) plantations
(Go
´mez-Pompa 1987). At present, most indigenous coffee growers recognise
Inga as a sort of archetypical shade tree, and promote its establishment by
means of seed. In turn, C. alliodora is a valuable timber tree, thus it is tolerated
in coffee plantations since it is viewed as a savings account that may be used to
cope with economic crises or emergencies such as sickness or debt. In addition
to management, ecological and historical factors determine the abundance of
these trees. Both are heliophytes that colonise plantations when other trees are
felled. They also invade disturbed areas such as the secondary growth where
coffee plantations are established, and remain in the system from then on.
Figure 5. Species accumulation curve in rustic coffee plantations at Rancho Grande.
1236

The conservation potential of coffee plantations
According to our calculations, the 34 tree species potentially harboured in the
whole coffee-growing area of Rancho Grande represent a richness similar to
that found in 0.1 ha of primary vegetation. Nonetheless, the fact that more
than half of the species in plantations are pioneers would lead to think that the
contribution of coffee plantations to the conservation of wild trees, mainly
those of the mature forest, is limited. However, such reasoning may overlook
other factors relevant in assessing their conservation role.
Table 4. Species list for the 0.1 ha plot of mature forest at Rancho Grande.
Family Species Relative abundance
Actinidiaceae Saurauia scabrida Hemsl. 0.03
Annonaceae Guatteria galeottiana Baill. 0.03
Arecaceae Chamaedorea pinnatifrons (Jacq.) Oerst. 0.01
Asteraceae Eupatorium araliaefolium Less. 0.01
Bignoniaceae Amphitecna macrophylla (Seem.) Miers ex Baill. 0.12
Clusiaceae Garcinia intermedia (Pittier) Hammel 0.02
Euphorbiaceae Cnidoscolus multilobus (Pax) I.M. Johnst. 0.01
Fabaceae Lonchocarpus sp. 0.04
Flacourtiaceae Casearia corymbosa Kunth 0.02
Flacourtiaceae Unidentified sp. 1 0.13
Flacourtiaceae Unidentified sp. 2 0.01
Lauraceae Beilschmiedia aff. mexicana (Mez) Kosterm. 0.01
Lauraceae Licaria capitata (Schltdl. & Cham.) Kosterm. 0.07
Lauraceae Nectandra longicaudata (Lundell) C.K. Allen 0.13
Lauraceae Persea schiedeana Ness 0.04
Malpighiaceae Bunchosia lanceolata Turcz. 0.01
Melastomataceae Miconia argentea (Sw.) DC. 0.02
Meliaceae Guarea glabra Vahl 0.03
Monimiaceae Mollinedia oaxacana Lorence 0.01
Moraceae Ficus sp. 0.01
Piperaceae Piper marginatum Jacq. 0.01
Rubiaceae Faramea schultesii Standl. 0.01
Rubiaceae Hamelia calycosa Donn. Sm. 0.01
Rubiaceae Hoffmania carlsoniae Standl. & L. Willians 0.01
Rubiaceae Hoffmania excelsa (Kunth) K. Schum 0.01
Rubiaceae Hoffmania nicotanaefolia (M. Martens & Galeotti)
L.O. Williams
0.02
Rubiaceae Psychotria costivenia Griseb. 0.01
Rubiaceae Psychotria panamensis Standl. 0.04
Rubiaceae Sommera sp. 0.10
Sapindaceae Cupania sp. 0.01
Sapotaceae Chrysophyllum mexicanum Brandegee ex Standl. 0.02
Tiliaceae Heliocarpus sp. 0.01
Turneraceae Erblichia odorata Seem. 0.01
Urticaceae Myriocarpa longipes Liebm. 0.01
Verbenaceae Callicarpa sp. 0.01
1237

The original stand cover affects floristic structure as a whole, especially in
recently established holdings; however, a tendency towards homogenisation in
composition with time was observed. Thus, after a period of around 20 years,
plantations originating from old secondary forests become similar to those
originally set on younger stands, whose mean floristic composition does not
undergo any changes (Figure 4). This convergence indicates that coffee growers
actually eliminate those species that are able to colonise stands with a more
advanced successional stage. Interviews with the cultivators pointed out that,
during the 20-year development stage of the plantation, shade trees are grad-
ually felled and replaced. This may explain why various mature-forest tree
species occurred only in young coffee plantations. An important conservation
implication of these results is that recently established plantations on old sec-
ondary growth stands have a larger potential to conserve native tree diversity.
At this point, it must be borne in mind that there is a complete lack of
synchrony in the development of coffee plantations. This is precisely why we
observed such a large spatial floristic heterogeneity among plantations, despite
the converging trend discussed above. Thus, it is necessary to take into account
the b-diversity of the whole system in order to adequately assess the contri-
bution of rustic coffee plantations to plant diversity conservation. In other
words, the number of tree species that could be maintained in all coffee
plantations of Rancho Grande depends mostly on the existing variation
between plantations. This variation is particularly important in the case of
mature forest trees, given that most of them occur in few plantations.
A further consideration in evaluating the conservation role of coffee plan-
tations in a given region is the extent and integrity of the surrounding forests.
In those regions where natural vegetation still covers large areas, rustic coffee
plantations may only play a minor role in biodiversity conservation. In con-
trast, in those areas where forest cover has been drastically reduced and
fragmented, as is the case of Rancho Grande, these plantations may stand out
as the only viable way of conserving native tree diversity.
Conclusions
Rustic coffee plantations of Rancho Grande are complex and floristically
highly heterogeneous. A single coffee plantation does not contribute signifi-
cantly to plant conservation. Rather, it is the sum of the heterogeneous patches
in the fragmented landscape which makes this agroforestry system valuable for
wild tree diversity conservation.
Acknowledgements
We thank the people of Rancho Grande for their valuable support and their
kindness while we stayed in the community. We also acknowledge their will-
1238

ingness to share their knowledge. This research was made possible by a
scholarship granted to the first author by the Universidade Estadual de Feira
de Santana, Brazil (1998–2000) through the program of Academic Improve-
ment of Technicians and Researchers. We are grateful to Sarah Dalle for the
English editing of the manuscript, as well as for their valuable suggestions and
comments. Juan Martı
´nez assisted during field work as well as in the botanical
identification of the voucher specimens collected. Jorge Saldı
´var and Laura
Corte
´s collaborated in the preparation of the figures.
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