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R E S E A R C H Open Access
Vulnerability and risk management of Agave
species in the Tehuacán Valley, México
América Delgado-Lemus, Ignacio Torres, José Blancas and Alejandro Casas
*
Abstract
Background: Our study analysed the vulnerability of the useful Agave species of the Tehuacán Valley, Mexico,
considering ecological, cultural and economic aspects, and management types. We hypothesized that management
intensity is proportional to the degree of risk of a species in order to decrease its vulnerability.
Methods: Distribution of Agave species was monitored in 36 types of plant associations. Ethnobotanical studies
were conducted in 13 villages and six markets. The vulnerability of each species was calculated by assigning risk
values to the variables analysed. The vulnerability and management intensity indexes were estimated through the
scores of the first principal component of PCA. Variation of management data explained by ecological, cultural and
economic information were analysed through canonical correspondence analyses (CCA). A linear regression analysis
identified the relation between vulnerability and management intensity.
Results: We recorded presence of agave species in 20 of 36 vegetation types. Out of 34 Agave species, 28 were
recorded to have one to 16 use types; 16 species are used as food, 13 for live fences, 13 for producing ‘pulque’,11
for fibre and ornamental, 9 for construction. Seven species are used for preparing mescal, activity representing the
highest risk. Seven Agave species are exclusively extracted from the wild and the others receive some management
type. Incipient cultivation was identified in A. potatorum whose seedlings are grown in nurseries. Intensive
cultivation through vegetative propagation occurs with domesticated species of wide distribution in Mexico. The
highest management intensity values were recorded in widely distributed, cultivated and domesticated species, but
the regionally native species more intensively managed were those with higher demand and economic value,
protected by collective regulations because of their scarcity. The regression analysis indicated significant relation
(R
2
=0.677, P<0.001) between vulnerability and management indexes. CCA explained 61.0% of variation of
management intensity, mainly by socio-cultural factors (30.32%), whereas ecological data explained 7.6% and the
intersection of all factors 21.36%.
Conclusions: The highest vulnerability was identified in wild species restrictedly distributed and/or highly extracted.
Social pressures may increase the natural vulnerability of some species and these species are particularly those
native species receiving some management form.
Keywords: Agave, Ecological ethnobiology, Non-timber forest products, Risk management, Sustainability, Tehuacán
Valley, Vulnerability
* Correspondence: acasas@cieco.unam.mx
Laboratorio de Ecología y Evolución de Recursos Vegetales, Centro de
Investigaciones en Ecosistemas, (CIECO), Universidad Nacional Autónoma
de México, Apartado Postal 27-3, Santa María Guido, C.P. 58090 Morelia,
Michoacán, Mexico
JOURNAL OF ETHNOBIOLOGY
AND ETHNOMEDICINE
© 2014 Delgado-Lemus et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the
Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public
Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this
article, unless otherwise stated.
Delgado-Lemus et al. Journal of Ethnobiology and Ethnomedicine 2014, 10:53
http://www.ethnobiomed.com/content/10/1/53
Background
The subfamily Agavoideae of the plant family Asparagaceae
includes species native to the Americas, naturally
distributed from southern USA to Bolivia and the
Caribbean Antilles [1]. The most diverse genus of the
subfamily is Agave, which includes 204 species [2]. A total
of 163 agave species occur in Mexico, 123 of them being
endemic to the territory of this country, a reason why
theareaisconsideredamaincentreoforiginand
diversification of the genus [2-6]. The Agave species
have great ecological importance in Mexico since they
are main components of arid and semiarid ecosystems
predominating in most of the Mexican territory. Also,
agaves are of high cultural and economic importance
in Mexico since they have been used by Mesoamerican
peoples from prehistoric times [7,8], and currently are
valuable non-timber forest products that increasingly
provide direct goods and monetary incomes to thousands
of rural families. Agaves are crucial plant resources for
most Mexican native cultures.
Our study focused on the Agave species of the Tehuacán-
Cuicatlán Biosphere Reserve (ahead shortly referred to as
the Tehuacán Valley), a region located in the south-eastern
portionofthestateofPueblaand the north-western part
of the state of Oaxaca, in central Mexico. This region
harbours the highest richness of Agave species in
México [2], and is therefore particularly important to
study both ecological and human cultural aspects of
this plant group. We analysed the diversity of uses of
all the species identified, their cultural and economic
importance, and ecological information in order to
examine the vulnerability of species and populations
associated to use intensity of their products. In addition,
we systematized the local experience of managing agaves
in the region. We analysed the relation between risk and
management responses to decrease vulnerability of par-
ticular species, and the viable perspectives of sustainable
management to decrease risk of the species studied based
on traditional ecological knowledge and technology.
A total of 34 Agave species has been recorded in the
Tehuacán Valley, 25 species and four infra-specific taxa
being native to the region, while seven of them are
endemic to the area [2,9]. Our previous ethnobotanical
studies carried out in the region have documented that
more than 20 of all agave species of the region are used
by local peoples in at least one of several use types [10].
The history of interactions between people of the Tehuacán
Valley and agaves is nearly 12,000 years old [8], and such a
long history allows supposing the existence of a deep
traditional ecological knowledge (TEK) accumulated
by the local cultures until present. The TEK of agaves by
local peoples includes topics such as use properties of
their parts that make them suitable for different purposes,
information about distribution and abundance, particular
habitats, interactions with other organisms (flower
visitors, herbivores, nurse plants, parasites and pests),
reproduction types, phenology, as well as management
techniques that were and are continually developed
and transmitted among human generations [10,11].
Uses reported for agaves in the region include live fences,
food, fibre, fuel, material for construction, medicine, fodder,
and alcoholic beverages such as ‘pulque’(a sap fermented
kind of wine) and ‘mescal’(a distilled spirit) [2,10,12-17].
Some studies have documented that agave products
represent a significant contribution to sustenance of rural
households of the Tehuacán Valley [10,12,16,18,19].
However, the extraction of their products is frequently
practiced without mechanisms directed to ensure their
maintenance for future availability. The over-exploitation
of some agave species has increased relatively recently
apparently in direct relation with the demand of their
products in the markets, which also increases the risk of
their extinction [20,21]. Sustainable forms of use of these
resources are currently indispensable, and because risk is
determined by complex interactions of socio-cultural,
institutional, biological, climatic and geographic factors
and processes, the sustainable management have to take
into account those factors and processes. This study
analyses some of the main factors affecting risk and
sustainability of Agave species of the Tehuacán Valley,
an information that may be useful for designing both
sustainable use and conservation policies.
The production of alcoholic beverages is particularly
important in some villages of the region, but agave
extraction involved in this activity determines high risk
of maintenance of wild populations of the Agave species
used and the biotic communities they form part. It is
common that extraction of agaves from wild populations
occurs without planning and with limited actions
directed to recover and conserve the populations
affected. These are for instance the cases of A. potatorum
and A. marmorata, which are the wild species mostly used
for producing mescal from whose populations’individual
plants are extracted before producing their inflorescences,
thus interrupting their sexual reproduction. Another
extreme of inadequate management may also be illustrated
in cultivated species such as A. angustifolia,whichin
Tehuacán is managed similarly to the industrial production
model of the tequila agave (A. tequilana var. azul)inother
areas of Mexico [22-24]. Plantations of A. angustifolia
progressively substitute forest areas through vegetative
propagules of relatively few clones, thus determining
impoverishment of vegetation composition and genetic
diversity of the cultivated populations of agave.
Ethnobotanical studies have documented a high diversity
of strategies of plant management in the Tehuacán Valley,
including several forms of gathering, silvicultural sys-
tems that involve the management of individual plants,
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populations and biotic communities, as well as agricul-
tural systems [11,12,25-28]. Silvicultural management
techniques involve the management of wild populations,
commonly in forest and agroforestry systems [12,27,29].
These practices are exceptionally important since they can
be implemented in biodiversity conservation programs at
either local or regional scales, as well as programs for
wellbeing of the regional human population.
Populations of several agave species are under different
management regimes in the region, the management
types being influenced by ecological, socio-cultural and
technological factors. Management includes human
interventions in order to achieve a balance between the
amount of products required to satisfy human needs and
the availability of plant or animal resources. Commonly,
the interaction between people and plants determines an
impact that depends on the intensity of extraction of
products and the technique implemented to obtain the
products. The form of this interaction may represent
risks to the viability of the plant resources associated to
its use. For instance, practices of extraction may involve
different plant parts (leaves, flowers, inflorescences or entire
individuals), different amounts (for direct consumption by
households or for commercialization), affecting differently
the capacity of a species to tolerate the harvest of its
products [30] and their recovering. Socio-cultural factors
may influence fluctuations in the demand of products or
their importance in satisfying a cultural requirement,
which may also be according to the substitutability of a
product for other. These aspects may influence the
intensity of the forest products extraction and may be
variable throughout time according to cultural, social
and economic changes.
Some rural communities have constructed agreements
and rules for regulating the access to products of some
agave species. These regulations may contribute to mitigate
negative impacts of forest extraction and influence the level
of organization of the communities for planning the use of
plant resources. Ecological aspects like distribution and
abundance of the species used may also influence the
magnitude of risk. An abundant and widely distributed
species has lower risk than other scarcer with a more
restricted distribution. Similarly, biological aspects such as
life cycle length, low capacity and slow regeneration of
parts extracted may determine higher risk in longer lived
plants with slow growth than in others with faster growth
and shorter life cycle. The type of reproductive biology is
also important, since agaves with vegetative propagation
are more easily recovered than those without this
propagation type; those species with self-compatible
breeding systems or with generalist pollinators may more
surely achieve sexual reproduction than self-incompatible
and/or with specialist pollinators. All these aspects
influence the degree of vulnerability of the utilized species.
In this study we report ethnobiological and ecological
information collected through our studies in relation to
distribution, abundance, use and management strategies of
the agave species in the Tehuacán Valley. We examined the
hypothesis that management strategies are proportional to
the degree of risk determined by ecological and social
factors and that the purpose of such management
strategies is to decrease vulnerability. To test this
hypothesis we constructed an index of vulnerability
integrating information for biological, ecological and
social indicators collected for the different species of
Agave of the region. We looked for identifying the most
vulnerable species and the most relevant factors influencing
such vulnerability. Accordingly, our study aimed at: 1)
integrating ecological and ethnobotanical information
of useful agave species in the Tehuacán Valley, in
ordertoanalysetheircurrentstateofvulnerability
and its relation to management types, and 2) discussing
conservation and sustainable management policies of agave
species at regional scale based on local TEK.
Materials and methods
Study area
The Tehuacán Valley is the southernmost semiarid area
of Mexico [31], located in the south-eastern portion of
the state of Puebla and the north-west of Oaxaca. The
total area is 10,000 km
2
, with the Biosphere Reserve
Tehuacán-Cuicatlán covering 4,300 km
2
(Figure 1). It is
delimited by the mountains of the Sierra de Zongolica
which determines the rain shade influencing the dryness of
the area [32]. Climates may be warm with annual precipita-
tion of 700 to 800 mm in the southeast, semi-warm with
annual average precipitation of 400 to 500 mm in the
central and western zones, and temperate with higher
annual precipitation in the highlands [33,34]. This region is
one of the main reservoirs of biological diversity of the arid
zones of México, including more than 3,000 species of
phanerogamic plants [32]. Ethnobotanical studies [10,16],
have reported more than 1,600 plant species utilized by
local peoples of eight indigenous ethnic groups inhabiting
the region [10].
The Tehuacán Valley comprises a wide variety of envi-
ronments determined by climates, soils, geomorphology
and elevation, which is reflected in nearly 36 types of plant
associations as described by Valiente-Banuet et al. [35,36].
Distribution of Agave species
In order to analyse distribution of agave species within
theterritoryoftheTehuacánValleywerecorded
their presence in all vegetation types described by
Valiente-Banuet et al. [35,36]. We have recorded data
of abundance (density and biomass) in some of those
areas through vegetation sampling. But since information
is incomplete for all vegetation types and all agave species
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Figure 1 The Tehuacán-Cuicatlán Biosphere Reserve in central Mexico. Location of the studied communities and regional markets.
Delgado-Lemus et al. Journal of Ethnobiology and Ethnomedicine 2014, 10:53 Page 4 of 15
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we did not include this information in the current
analysis.
Ethnobotanical and vulnerability studies
Ehnobotanical information about use types and plant parts
utilized (Figure 2), management, cultural and economic
values was collected in a total of 13 rural communities and
six regional markets (Figure 1). In the communities studied,
a total of 176 persons provided information about agaves in
a period of eight years. These were general ethnobotanical
studies in relation to useful flora of the communities
and the information is comparable. These studies were
conducted through ethnobotanical collecting and semi-
structured interviews which allowed contextualizing use of
agaves in the different aspects of life by local people, in the
general context of the role of plants as provider of
food, medicines, live fences, fuel, fibres, among other
uses. In each study, we selected at random 20 households
per village but not always was recorded information about
agaves.
Ethnobotanical studies were particularly directed to
obtain deeper information about Agave potatorum,A.
marmorata and A. salmiana, three species identified to
be in particular high risk, as well as in relation to all
agave species. The specialized studies on agaves included
focal groups with nearly 80 persons in two villages
(San Luis Atolotitlán and Santa María Ixcatlán), and
samples of 36 informants that participate in different
aspects of production of mescal. The deeper studies
on agave allows a more precise relative hierarchical
information about the perception of the importance
of agaves by local peoples. The specific interviews
were directed to deeper information about use and
forms of preparation and particularly about management
techniques and relative comparisons of the cultural and
economic importance of the products provided by agaves.
Finally, interviews in the markets were directed to identify
amounts, frequency, prices, demand of products of
agave species in the regional markets. Studied of
commercialization of agave products in the six main
markets of the region of the Tehuacán-Cuicatlán Valley in
a period of two years, to 40 persons that sell mescal,
flower buds and other useful products of agaves in the
markets. The information is complementary and allows a
general view of the importance of agaves in the regional
context.
A data base was constructed in order to systematize
the ethnobotanical and ecological information about
distribution and biological information about the repro-
ductive system, the length of life cycle, among the most
meaningful features. The vulnerability of agave species
was determined in a relative scale based on the impact of
parts collected and intensity of extraction according to the
criteria explained in Table 1.
Data analyses
In order to identify the different conditions of vulnerability
based on variables related with social and ecological risk, a
principal component analysis (PCA) was performed. The
vulnerability index was determined as the score of the
first principal component, which is an integration of
information of the most meaningful variables analysed.
Similarly, different indicators of plant management were
analysed through PCA and the score of the first principal
component was used as index of management intensity.
The relation between vulnerability and management inten-
sity was analysed through a regression analysis. Amounts
of variation of management data explained by ecological,
cultural and economic information, as well as their vulner-
ability level were analysed through canonical correspond-
ence analyses (CCA) CCA were performed to measure the
amount of variation of management data explained
from ecological and sociocultural information. The
analyses were conducted using the R software following
Blancas et al. [28]. We used three matrices partitioning
the variation: Matrix Y containing the response variables
Figure 2 Parts of the agave plants analysed in this study.
Common names recognized by local people in the Tehuacan Valley
and the botanical names of plant parts are included.
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(management intensity data matrix), matrix X with the set
of explanatory ecological variables; and matrix W with the
set of explanatory sociocultural variables. The main
purpose of this analysis is to cope with the confounding
effectsthatmayoccurifaCCAofYismadeusingWorX
as the only explanatory matrix. That is, some variables of
W may influence variables of X and vice versa. Through
this method we conducted several CCA combining sets of
explanatory variables: 1) Correspondence Analysis (CA)
only for matrix Y, 2) CCA for matrix Y vs. matrix W, 3)
CCA for matrix Y vs. matrix X, 4) CCA for matrix Y vs.
matrices W+X. The total constrained eigenvalue of
each analysis was tallied to identify how much of the
management intensity matrix is explained by ecologic
and sociocultural data. This method allowed dividing
CCA variation into four parts: a) Ecological data, which is
the fraction of management intensity variation that can be
explained by ecological data independently of sociocultural
data, b) Sociocultural + ecological data, c) Sociocultural
data which is the fraction of management intensity
variation that can be explained by sociocultural data
independently of ecologic data, and, d) Undetermined data
or fraction of management intensity variation explained
neither by ecological nor by sociocultural data. For each of
these analyses, the sum of all canonical eigenvalues divided
by the sum of all canonical eigenvalues, allowed calculating
the corresponding fraction of variation explained by the
analysis. Significance of the models for each CCA was
estimated by permutation tests for: a) the whole model, b)
management intensity explained by ecological variables
Table 1 Criteria used to define the values of vulnerability of Agave species according to socio-cultural, economic,
ecological, and biological indicators
Variable Criterion Value
Useful part Use of dead plant parts 0
Use of vegetative parts (leaves, fiber, spines) 1
Use of sap and reproductive parts (flower buds, inflorescences 2
Use of the entire plant 3
Management Cultivated, domesticated, and introduced species (no wild populations occurring in the region) 0
Wild native species cultivated ex-situ by seeds 1
Wild native species cultivated ex situ through vegetative propagules 2
Wild native species tolerated and protected in situ in modified originally natural areas 3
Wild native species under simple gathering of vegetative parts (leaves) and vegetative sprouts. 4
Wild native species under simple gathering of reproductive parts (flowers and inflorescences) and entire
individual plants before sexual reproduction
5
Demand in markets Not interchanged in markets 0
Commercialized or bartered in markets 1
Ecological status Cultivated introduced species 1
Wild and cultivated species 2
Only wild populations 3
Propagation Seeds, caespitose and rhizomatous suckers and/or bulbils 1
Seeds and multiannual rhizomatous suckers 2
Seeds and low production of early rhizomatous suckers 3
Seeds and axilar suckers 4
Exclusively seeds 5
Distribution in regional
vegetation types
Occurring in five or more vegetation types 1
Occurring in four regional vegetation types 2
Occurring in three regional vegetation types 3
Occurring in two regional vegetation types 4
Occurring in one single regional vegetation type 5
Distribution in other regions
of Mexico
Cultivated broadly distributed species 0
Occurring in more than six states of Mexico 1
Occurring in two to five states of Mexico 2
Endemic to the region 3
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and 3) management intensity explained by sociocultural
variables.
Results
Uses
Agave species are strongly rooted in cultures of local
peoples of the Tehuacán Valley. From a total of 34 species
recorded 28 have at least one use. Table 2 summarizes
information on the variables used for analysing the
ecological, social and cultural aspects for each species
studied. Agave marmorata is the species with the
highest number of uses (14), followed by A. potatorum
with 12. Nearly 25% of the species analysed have one
single use (Figure 3). The main uses of agave documented
in this study are:
i. Food, particularly appreciated are flower buds
(‘cacayas’) and escapes (‘quiotes’) which are prepared
boiled and cooked in various stews. Also important
are the stems of mature plants which are cooked in
underground ovens producing a sweet fibrous meal
(the product is called ‘mezcalli’). A total of 16
species were mentioned to provide edible parts
(Table 1).
ii. Live fences which are mainly destined to limiting
plots, protecting them to the access of livestock and
to conform barriers or lines to retain soil and water;
live fences with agaves are particularly important in
agroforestry systems out of the villages, as well as in
homegardens. A total of 13 species were mentioned
to be commonly used for this purpose (Table 1).
iii. Alcoholic beverages, which are prepared as ‘wine’
or ‘beer’by fermenting the sap, this beverage is
called ‘pulque’, and it is mainly prepared with A.
americana var. americana,A. salmiana subsp.
tehuacanensis,A. atrovirens,A. marmorata and a
total of 13 species. The distilled beverage is called
mescal. It is distilled after fermenting the cooked
stems, and the most important species used in the
region are Agave potatorum, A. americana var.
oaxacensis,A. macroacantha, and A. marmorata,
and other species, seven in total.
iv. Fibre, which is used as raw matter to manufacture
cords or ‘yute’and ‘ixtle’; these materials in the
pre-Columbian times were as important as cotton
for netting and clothing. A total of 11 species are
currently used for obtaining fibre.
v. Ornamental. In total, 11 agave species are used as
ornamental plants, the most appreciated are A.
triangularis,A. macroacantha,A. stricta,A.
americana,A. marmorta, and A. potatorum.
vi. Biofuel, the remains of dead adult agaves (called in
Náhuatl ‘mezote’) are much appreciated as fuel.
Particularly important are those large size species.
vii. Nine agave species provide material for
construction, particularly the escapes of several
species which are valued as wooden material for
supporting roofs, walls and fences in traditional
constructions. In some villages the escapes are used
as pipes conducting water, whereas in other villages
the leaves are also used for thatching houses and
fibre is used to make cords for tiding structures of
the houses. Particularly important for construction
are the escapes of A. scaposa and A. salmiana var.
tehuacanensis. For corral fences and platforms for
storing stubble are preferred the smaller escapes of
A. potatorum and A. kerchovei.
viii.Tools, large escapes are used for manufacturing
ladders, whereas the thinner and longer escapes are
used as pole vault or ‘chicoles’used for collecting
fruits from trees and columnar cacti.
ix. Fodder, the young plants and escapes in early stages
of formation are consumed by livestock, mainly
cattle and goats. Eight species are fodder, A.
angustiarum;A. angustifolia var. angustifolia,A.
atrovirens var. mirabilis,A. kerchovei,A.
macroacantha,A. marmorata,A. potatorum and A.
scaposa.
x. Medicine, six agave species are medicinal. Their
roosted leaves are anti-inflammatory and analgesic
used to relieve luxation pain; leaves infusions are
used for bronchitis and as anti-inflammatory of
internal organs, as well as anticoagulant. The cooked
stem called “mezcalli”is used for bronchus
affections. The alcoholic beverage called mescal is
used as other spirituous beverages, for relieving
stomach ache, tonic for whetting appetite, and
drinking it with honey and lemon is used for relieving
cold; it is also used rubbing feet and the back together
with branches of the tree ‘pirul’(Schinus molle)for
relieving fever and ‘heating cold feet’.Mescalisalso
used to prepare tinctures with medicinal plants and
poultices for treating rheumatic and traumatic pains.
xi. The leaf cuticle, called ‘mixiote’is used to envelope
food, mainly meat that is cooked underground; it is
a material of high demand and price in markets.
Two species were mentioned to be used for
extracting mixiote.
xii. Ritual and religious, mainly for preparing altars in
religious celebrations (two species).
xiii. Soap, A. triangularis was referred to be used as
soap for washing clothes because of its high
content of saponins.
Useful parts
In the case of Agave marmorata we found the use of six
plant parts, A. potatorum, A. seemaniana and A. kerchovei
provide five useful parts. In total, 17 species provide two
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Table 2 Information about ecological, socio-cultural and management aspects of the useful Agave species recorded in the Tehuacán Valley
Species Ecological
status
Vegetation types
occurrence
Distribution Life
cycle
Reproduction
forms
Management
types
Sites
proximity
Collective
regulations
Artificial
selection
Use
types
Used
parts
Harvest
type
Commercial
value
Medicinal
use
A. americana var.
americana
10 0 12 2 01 22221 0
A. a. var. marginata 10 0 12 2 11 21021 0
A. a. var. oaxacensis 10 1 12 2 11 22321 0
A. angustiarum 33 1 11 5 01 13210 0
A. angustifolia 10 1 12 3 11 22111 0
A. angustifolia var.
angustifolia
14 0 12 2 11 21221 0
A. applanata 23 1 12 4 01 11110 0
A. atrovirens 32 2 11 3 21 21220 0
A. atrovirens var.
atrovirens
35 2 11 2 11 22221 0
A. atrovirens var.
mirabilis
25 2 11 2 11 22220 0
A. chiapensis 30 2 22 4 01 11210 0
A. convallis 35 2 12 4 01 11110 0
A. ghiesbreghtii 35 2 22 3 01 12110 0
A. karwinskii 24 2 12 2 21 12121 1
A. kerchovei 34 2 12 4 21 22211 0
A. macroacantha 24 2 12 5 21 23221 0
A. mapisaga 14 0 12 2 11 22221 0
A. marmorata 34 2 12 4 21 24321 3
A. nussaviorum subsp.
nussaviorum
35 3 11 5 01 12310 3
A. peacockii 35 2 12 4 01 23220 0
A. potatorum 33 2 11 1 22 24321 3
A. salmiana subsp.
salmiana
22 2 12 2 11 22221 0
A. salmiana subsp.
tehuacanensis
23 2 12 3 21 23320 0
A. scaposa 31 2 11 3 02 23020 2
A. seemanniana 10 2 11 5 21 23321 1
A. stricta 32 2 22 4 01 22211 0
A. titanota 30 2 12 5 01 22320 0
A. triangularis 34 2 22 5 01 13210 0
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to four useful parts and eight species provide one single
useful plant part. Figure 2 shows the agave plant parts
considered in the analysis, indicating their regional names
and their equivalent botanical names. The entire living
plants of 16 species are transplanted in situ or ex situ as
living fences and borders or terraces, A. marmorata
and A. americana var. americana are the most common.
Flower buds and inflorescences of nearly half of the
species analysed are used.
Economic value
In total, 11 species were reported to have commercial
value and 17 were not (Table 2). This information
could be underestimated since some agave products
are occasionally interchanged or bartered at local level in
the villages and were not easily recorded. For instance,
mescal producers interchange mescal for maize and other
products in the local stores, or even for other products
used for producing mescal (agave plants, fuel wood, or
labour hand). The commercial value is an indicator of the
amount of demand of an agave species or its product, but
the risk is not necessarily a factor determining risk, it
depends of other aspects as well. For instance, a
household that collect flower buds for commercialization
in the regional markets does not determine an impact
similar to that determined by a mescal producer
household, which may extract 200 individual plants for
one single production event. Even lower impact can be
identified in practices for collecting dry escapes for
construction and manufacturing tools. In these cases the
agaves have died and released their seeds and, therefore,
impact being null. However, escapes of A. marmorata are
massively cut for ornamental purposes in the village of
Zapotitlán during the blooming period, and those of
A. salmiana ssp. tehuacanensis are harvested in San
Luis Atolotitlán, Puebla, inhibiting the development
of flowers, fruits, and seeds, decreasing the possible
contribution of sexual reproduction.
Management
The following forms of interaction between local peoples
and agave were identified:
(1) Out of the 28 species of Agave reported with some
use in the Tehuacán Valley, seven are extracted
exclusively from wild populations (simple gathering)
whereas the remaining species receive at least one
management type.
(2) The most common management type is extraction
of entire individual plants while transplanting
seedlings or young plants to anthropogenic areas
(ex situ transplanting). This are the cases of A.
atrovirens var. atrovirens,A. karwinskii,A.
macroacantha and A. titanota.
(3) The practice referred to above is followed in
frequency by the extraction of plants exclusively
Figure 3 Number of Agave species (ordinate axis) of the Tehuacán Valley identified in this study with different use types.
Delgado-Lemus et al. Journal of Ethnobiology and Ethnomedicine 2014, 10:53 Page 9 of 15
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from wild populations but at the same time people
may practice in situ propagation of propagules, as in
the cases of A. angustiarum, A. kerchovei,A.
peacockii,A. stricta and A. scaposa.
(4) Then, it can be mentioned the importance of the
vegetative propagation of domesticated, introduced,
and widely distributed species such as A. americana
var. americana,A. americana var. marginata,A.
angustifolia var. angustifolia and A. mapisaga.
(5) There is in addition the incipient cultivation of Agave
potatorum in green houses, particularly in San Luis
Atolotitlán and Caltepec, Puebla, where local people
have had the initiative to produce plants for recovering
wild populations. Plants produced are therefore
reintroduced to the original wild areas, but they started
to test their success in small plots of agroforestry
systems and in abandoned agricultural areas.
(6) Finally, we recorded the intensive cultivation of
plantations of A. angustifolia and more recently also
A. tequilana var. azul which are intensively produced
as monocultures in plots using agrochemicals.
(7) However we identified another management form.
Extraction of agave sap for preparing ‘pulque’is one
of the most ancient uses of agaves. Plants used for
this purpose are propagated through vegetative
propagules, mainly to areas close to the houses in
the village, as well as to areas surrounding the
agricultural plots and homegardens and even along
roadsides. It is an example of small scale cultivation.
These are the cases of A. americana var. americana
and A. atrovirens var. atrovirens.
(8) Other species like A. stricta,A. macroacatha and A.
potatorum are cultivated in nurseries of local Units
of Environmental Management (UMAs for their
abbreviation in Spanish), where local people
propagate seeds collected in wild populations and
sell young plants as ornamental. This is part of a
strategy directed to decrease the illegal extraction of
plants from the biotic communities by international
illegal trade industries.
Vulnerability index, species in risk and management
intensity
The principal components analysis classifies the agave
species recognizing two main groups, one of them is
composed by the cultivated agaves, domesticated or in
process of domestication or recently introduced to
cultivation because of their commercial value. The
other group is composed by wild agaves with low or null
commercial value (Figure 4). This analysis identifies the
important weight of the commercial value of products in
their classification (Table 3).
The regression analysis in Figure 5 indicates the highly
significant linear relation between risk and management
intensity indexes (R
2
= 0.677, P < 0.001). Partitioning CCA
explains 61.0% of the management variation as shown in
Figure 6. This variation can be explained mainly by
sociocultural factors (30.32%) while ecological data explain
7.6%. Intersection of ecological and sociocultural factors
explains 21.36% and is statistically significant. Unexplained
variation was 39.0%. Four variables of the intersection of
ecological and sociocultural indicators were particularly
important: ecological status, life cycle, type of harvest and
interchange or not of the agave products (Table 4).
Figure 5 shows that the most vulnerable agave species
are Agave nussaviorum subsp. nussaviorum,A. peacockii,
A. convalis, Agave potatorum and A. triangularis, most
of them with restricted distribution or intensively
extracted. Those with intermediate vulnerability are Agave
marmorata,A. titanota,A. atrovirens var. atrovirens,A.
scaposa,A. salmiana subs. tehuacanensis,A. salmiana
subsp. salmiana. The least vulnerable species are Agave
mapisaga,A.angustifolia var. angustifolia, A. americana
var. americana and Americana var. marginata which are
domesticated, introduced and widely distributed.
Discussion and conclusions
Use and management
In the Tehuacán Valley, the species of agave are among
the more used and appreciated plant resources and also
those more intensively managed by people of the region.
Most of them are resources located in communal land
and therefore of free access to local people. Different
parts of the plants are used which are available mainly
during the dry season when most of the wild plant
resources are not available. The high cultural and
economic importance of their products and their intensive
extraction determine that some species, particularly those
that require using the entire plant, have also high risk
of disappearing. It is possible to identify a delay in
constructing agreements and institutions regulating
the access to agave products; this is probably a fact
related to the relatively recent and rapid pressure developed
on agave resources. According to local people, local agave
populations that are now extinct were abundant until
recently (nearly 40 years ago). This pattern is particularly
clear in those species with high commercial value like
Agave potatorum, a species appreciated for preparing
mescal with increasing demand in the regional and
national market. The pattern contrasts also with that
of other species mainly used to satisfy needs of direct
consumption by households, and even more with
those species whose use is being lost, as it is the case
of the ‘pulque’agaves like Agave salmiana, since pulque
has been progressively substituted by more prestigious
beverages like beer [28]. A similar situation can be
observed in some species that in the past were used
for extracting their fibres like Agave angustiarum,
Delgado-Lemus et al. Journal of Ethnobiology and Ethnomedicine 2014, 10:53 Page 10 of 15
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Agave peacockii and Agave angustifolia.Theirfibre
has been substituted by plastic cords and these species
are now mainly used for producing mescal, which is a
more profitable activity.
Regulations of access and extraction of common wild
populations were recorded for some species, particu-
larly those that have several uses. In those cases people
have developed strategies that include regulated extrac-
tion in different seasons of the year. This is for instance
the case of the extraction of the escapes of Agave
salmiana subsp.tehuacanensisused for construction of
houses which in San Luis Atolotitlán, Puebla are ex-
tracted in two or three specific days, according to the
community extraction agreements.
From the analysis of vulnerability, it is clear that
while more forms of management are practiced the vul-
nerability decreases. Management of agaves may occur
in the wild (in situ including tolerance), as well as in
anthropogenic environments (ex situ, including trans-
planting of young plants and seeds sowing). Particularly
important are the agroforestry systems in the field,
located out of the villages [29,37,38], where people
practice a mixture of in situ and ex situ management
techniques. But also important are homegardens,
where people cultivate ex situ several species of Agave
either wild or domesticated. The agroforestry systems
in the field and homegardens are viable options for
propagating agaves, not only with lower environmen-
tal impact than the intensive agave plantation for
commercial tequila and mescal, but also for planning con-
servation of rare species and genotypes.
Vulnerability index
The cluster (Figure 4) and principal component (Figure 5)
analyses performed consistently show the importance of
the commercial value for explaining the vulnerability of
the agave species studied, the higher the economic
value the higher the risk. But this is also a function
of the distribution (the higher the distribution the
lower the risk), abundance (the scarcer the resources
the higher the risk) and the status of management as
discussed ahead. Those exclusively wild species have
higher risk than those wild regulated or in situ managed
species; have even more risk than those that are wild and
cultivated and even more than those that are exclusively
cultivated. Figure 5 shows the place of each of the 28
species of Agave studied in a Euclidean space which in
turn reflects a management gradient.
The vulnerability index (Figure 6) indicates that
the most vulnerable species are five native species
with relatively intermediate distribution, except Agave
nussaviorum subsp. nussaviorum, which has restricted
distribution and is the most vulnerable species of all the
species analysed. The five most vulnerable species are
extracted exclusively from the wild, although for Agave
potatorum some practices of incipient management
have started to be carried out such as the protection
of populations through communitarian regulations or
cultivation for being reintroduced in their natural
habitats. But these practices are recent, carried out by
some persons without interchanging experiences to each
other. Among the species with intermediate vulnerability
we identified both wild and cultivated agaves of relatively
Figure 4 Spatial arrangement of Agave species of the Tehuacán Valley according to the Principal Component Analysis performed with
socio-ecological variables. Sp1 = Agave americana var. americana, Sp2 = A. americana var. marginata, Sp3 = A. americana var. oaxacensis,
Sp4 = A. angustiarum, Sp5 = A. angustifolia, Sp6 = A. angustifolia var. angustifolia, Sp7 = A. applanata, Sp8 = A. atrovirens, Sp9 = A. atrovirens var.
atrovirens, Sp10 = A. atrovirens var. mirabilis, Sp11 = A. chiapensis, Sp12 = A. convallis, Sp13 = A. ghiesbreghtii, Sp14 = A. karwinskii, Sp15 = A. kerchovei,
Sp16 = A. macroacantha, Sp17 = A. mapisaga, Sp18 = A. marmorata, Sp19 = A. nussaviorum subsp. nussaviorum, Sp20 = A. peacockii, Sp21 = A.
potatorum, Sp22 = A. salmiana subsp. salmiana, Sp23 = A. salmiana subsp. tehuacanensis, Sp24 = A. scaposa, Sp25 = A. seemanniana, Sp26 = A.
stricta, Sp27 = A. titanota, Sp28 = A. triangularis.
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broad distribution. Almost all of these species, with the
only exception of A. scaposa, provide reproductive parts
or the entire plant as useful product, determining high risk
[37] which in part is counterbalanced through the
strategies of asexual reproduction in addition to propaga-
tion through seeds. A. scaposa reproduces exclusively by
seeds but its useful product (dry escapes) are used
after reproduction. Among the least vulnerable species
we identified those domesticated, introduced and broadly
distributed.
The vulnerability index of Figure 6 provides useful
information for guiding actions and regulations in order
to protect endangered agave species, as well as factors
that should be taken into account for designing and
implementing policies. For instance, it has been discussed
some aspects to be considered when using Agave species
with different degrees of vulnerability. From our current
analysis it is clear the importance of documenting
socio-cultural factors together with ecological infor-
mation, particularly their distribution, abundance and
type of reproduction. This information provides the
basic data for designing strategies for their sustainable use.
It is also crucial that any strategy implemented
could be periodically monitored in order to consider
uncertainty and surprises associated to the complex
socio-natural systems involved in agave management, but
also in order to progressively improving the management
based on previous experiences. Most agave species are
exclusively wild and in situ management of populations is
particularly important; but several regional experiences
have demonstrated that a combination of germinating
seeds in controlled conditions and nursing of young plants
may be effective to increase the amount of plants in
relation to the amount of available seeds. However, the
local experience also reveals that reintroduction of plants
into natural habitats requires ecological information about
the interaction with other natural nurse plants that pro-
vide micro-environments that are crucial for successful es-
tablishing of young plants. For some species, plantations
in degraded soils are not only possible but also one way to
recover ecosystem functions while providing useful
products and monetary incomes to local people.
Below, we provide some general recommendations in
order to promote more sustainable forms of management
of agaves in the Tehuacán Valley.
Extraction planning
Monitoring species and their populations available within a
territory provides the basis for planning actions. This
panorama makes possible identifying areas for carrying out
the use of products during different production seasons
and years. Some experiences in Chilapa, Guerrero, Mexico
have documented the organization of communitarian
committees with the charge of planning and monitoring
extraction of useful products as well as actions for
recovering the affected populations [39]. In some cases the
proportion and relation of wild and cultivated areas should
be considered in the monitoring activities since for some
species wild and cultivated populations are sympatric.
Wild populations
Counting of reproductive individual plants and identifying
and labelling the number of escapes that have to be
respected when extracting wild products is necessary in
order to ensure a minimum of seeds that are required for
both natural and artificial propagation of agave plants.
A method similar to that mentioned here has been
practiced by the communities of Guerrero, Mexico in
areas producing mescal (the Asociación de Magueyeros y
Table 3 Vulnerability and management intensity indexes
estimated for the different agave species utilized in the
Tehuacán Valley
Species Vulnerability Management
intensity
A. nussaviorum subsp. nussaviorum 1.83122 1.708526199
A. peacockii 1.1645 0.594045546
A. convallis 1.04956 1.126756957
A. potatorum 0.91661 −0.502843702
A. triangularis 0.89015 1.801632007
A. titanota 0.82558 0.380721625
A. atrovirens 0.73993 −0.136474466
A. kerchovei 0.5566 0.12302843
A. angustiarum 0.45358 0.923424365
A. scaposa 0.43271 0.098578612
A. marmorata 0.41184 0.12302843
A. stricta 0.40192 0.925191476
A. ghiesbreghtii 0.3376 1.512068797
A atrovirens var. mirabilis 0.30958 −0.229081914
A. chiapensis 0.25838 1.298744876
A. atrovirens var. atrovirens 0.24885 0.113410498
A. salmiana subsp. tehuacanensis 0.20267 −0.483614095
A. macroacantha 0.01962 −0.034892874
A. seemanniana 0.00464 −0.611475086
A. applanata −0.06403 0.312134623
A. salmiana subsp. salmiana −0.58286 −0.552045154
A. karwinskii −0.67297 −0.055894786
A americana var. oaxacensis −1.3218 −1.366667488
A. mapisaga −1.4866 −1.361323377
A. angustifolia −1.48899 −1.182096381
A. angustifolia var angustifolia −1.61646 −1.361323377
A. americana var. americana −1.79597 −1.483920345
A. americana var. marginata −2.02585 −1.6796394
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Mezcaleros del Chilapan) [39] and their experience may
be replicated in other areas for managing mescal agaves.
Additional suggestions for more effective recovering of
populations are:
Collecting seeds from several sites in order to ensure
diversity of sources of genetic material. This practice
may favour the availability of plant material from
several areas as well as options for adapting the
propagated material to establish in different
environments. Production of plants in nurseries may
optimize the production of plants from relatively few
seeds, but this practice should be complemented with
dispersion of seeds under the canopy of natural nurse
plants. Where survival of young plants may be more
successful than those transplanted from nurseries.
Transplanting of young plants of agave under the
canopies of specific nurse plants recognized by
previous ecological research available in the literature.
In addition it is recommendable to conduct
experiments to test the successful establishing of
seedlings and young plants under artificial shade.
Recovering populations of agaves in areas identified
as areas of extinction of local populations, as well as
in areas where populations are being impacted by
human activities, and finally as plantations in areas
that were cleared for agriculture in the past. These
areas may be benefited from soil recovering
associated to presence of agaves. Mescal production
could be centred in these areas rather than form
populations from natural forests.
Nurseries
Rustic local materials can be used for preparing nurseries.
In Sola de Vega, Oaxaca, the mescal producers of the
Sociedad de Producción Rural el Solteco produce A.
potatorum,A. angustifolia and other species in rustic
wooden beds in areas thatched with shrubs and palm
leaves.
Cultivated species
Young plants may be produced from seeds collected in
the region or, in some species, from vegetative propagules.
Interchange of seeds and vegetative propagules from
different zones is recommendable in order to increase
options for different purposes and environments where
the plant material will be propagated. It is highly
recommendable experimenting transplantation of young
plants in agroforestry systems either in the field out of the
villages [29,37,38] or in homegardens. These systems are
recognized to harbour high proportions of natural
vegetation and, therefore, this practice may reinforce
the role of biodiversity conservation of these systems.
Plantations should be directed to recover plant cover
of deforested and eroded areas. However, this task is
still particularly difficult and more techniques are still
needed to be developed.
Protection of pollinators
Bats are the most important pollinators of most agave
species of the Tehuacán Valley. Unfortunately, in the
past some governmental agencies promoted campaigns
for eradicating them with the erroneous idea that bats
Figure 5 Regression analysis of the management intensity index as a function of the vulnerability index calculated as the scores of the
first principal componente of the PCA of ecological, socio-cultural and management factors studied (R
2
= 0.677, P < 0.000).
Delgado-Lemus et al. Journal of Ethnobiology and Ethnomedicine 2014, 10:53 Page 13 of 15
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promoted illnesses. It is therefore necessary to promote
campaigns for protecting bats which are crucial for
pollination of agaves and numerous other groups of
plants. Reproductive success of species that entirely
depend on sexual reproduction for their viability (A.
convallis,A. nuusaviorum,A. peacockii,A. potatorum,
A. scaposa and A. seemanniana)willinturndependon
the success of protection of bats and other pollinators.
Survival and permanence of agave populations depend
mainly on actions of those that use them. However,
authorities of the Biosphere Reserve may provide
support in numerous campaigns of information and
favouring fair commerce of products. Regional policies
for sustainable use of local resources are possible and
necessary and local authorities have a clear responsibility
to achieve this task. The academic sector that carry out
research in the region should be more active in directing
their studies to understand key aspects that are necessary
for designing sustainable forms of management of
non-timber forest products without forgetting the
thousands of years of experience of local people. Scientific
research may be extraordinarily valuable tool when
complementing initiatives by local peoples.
Competing interests
The authors declare that they have no competing interests.
Authors’contributions
AD-L main author, involved in the study design, conducted interviews, field
work, literature review and general data collection and systematization,
wrote the first draft and concluded the final version of this manuscript. IT
and JB contributed to designing and following progress of the research and
field work and data analyses. AC main coordinator-supervisor of the research
project; contributed with original data and the designing of all the researches
providing the information for the current analysis; participated in fieldwork,
systematization and analysis of data and reviewed several drafts of the
manuscript. All authors read and approved the final manuscript.
Authors’information
AD, IT, JB postgraduate students at the Centro de Investigaciones en
Ecosistemas (CIEco), UNAM. AC full time researcher at CIEco, UNAM.
Acknowledgements
The authors thank the Posgrado en Ciencias Biológicas, UNAM and the
Consejo Nacional de Ciencia y Tecnología CONACYT for supporting PhD
studies of AD, IT and JB. The Programa de Apoyo a Proyectos de
Investigación e Innovación Tecnológica (PAPIIT projects IN205111-3 and
IN209214) and CONACYT (CB-2008-01- 103551) for financial support of the
research. We specially thank EdgarPérez Negrón for fieldwork assistance and
people of the Tehuacán Valley for their hospitality and participation in
interviews and sharing their knowledge.
Received: 13 May 2014 Accepted: 21 June 2014
Published: 3 July 2014
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doi:10.1186/1746-4269-10-53
Cite this article as: Delgado-Lemus et al.:Vulnerability and risk
management of Agave species in the Tehuacán Valley, México. Journal
of Ethnobiology and Ethnomedicine 2014 10:53.
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