Mr. David GANZ, APO-FAO
Kasetsart University, BANKOK
As one of the most diverse biological regions in the seasonal tropics, Oaxaca's main management challenge is balancing sustainable forest harvesting with preserving biological diversity, especially challenging for a village community with limited resources - both economic and technical. Medicinal plants and other non-timber forest products are especially sensitive to exploitative harvesting regimes. This paper takes a closer look at the forest management activities of communities in two regions of Oaxaca, Mexico. The Chimalapas and the Sierra Del Norte are discussed as an example of the ways in which changing cultural values, traditions and economies, affect local strategies of resource use and management. Through an analysis of barefoot silviculture and traditional medicine in these two regions, this papers aims to shed light on the complex social, political and historical forces affecting land use management in Oaxaca today.
This paper also demonstrates the need for integrative silvicultural systems that are adaptive, giving communities the flexibility to respond to failures and ever-changing conditions. Community forestry in this part of the world has fostered a great sense of responsibility and better stewardship of the land through the manipulation of standard silvicultural procedures and their integration with traditional agricultural practices. These community-based management approaches better integrate indigenous knowledge and traditions in management decisions. Further, indigenous peoples' efforts to develop their own management plans and silvicultural techniques are important not only in promoting ecological and economic sustainability, but also cultural sustainability, which is essential for the survival of the indigenous medical knowledge, values and traditions.
Keywords: Oaxaca, silviculture, barefoot silviculture medicinal plants, community forestry, indigenous knowledge, Zoque, Zapotec, Chinantec, indigenous people.
Oaxaca is one of the most biologically diverse states in Mexico. The region, which covers an area of about 10,000 km2, is home to approximately 6,000 plant species. Further, new species of plants are regularly reported by scientific journals. Oaxaca's natural environment is highly varied in terms of both geography and culture. Dissimilar climates, resulting largely from the mountainous topography, have given rise to many vegetation types and endowed the area with a wealth of diverse flora and fauna. The area's diverse ecosystems have also helped foster the emergence of indigenous cultures with highly complex medical systems. Moreover, out of Oaxaca's distinctive natural environments and cultures have evolved an assortment of traditional uses for medicinal plants. Oaxaca's main management challenge is balancing sustainable forest harvesting with preserving biological diversity and indigenous knowledge, especially challenging for a village community with limited resources - both economic and technical. The Chimalapas and the Sierra Del Norte are discussed as an example of the ways in which changing cultural values, traditions and economies, affect local strategies of resource use and management.
For centuries, Oaxaca was one of Mexico's cultural and economic meccas. Oaxaca's present social and political status still reflect its former dominance. According to the literature there are more than 18 ethnic groups in Oaxaca including the Zoque, Zapotec, Chinantec, and Mixtec (Gonzales, 1942). However, in the Chimalapas region alone, an area 600,000 hectares in size, local people believe there are at least 30 ethnic groups (pers. comm. Issac Matus 1996). The Zoque are the most prominent indigenous group in the state of Oaxaca (Cervantes Servin et al., 1990), and have long inhabited the Chimalapas region. The Zoque purchased the area back from the Spanish Conquistadores with gourds of gold in the early 1700s. Some of these indigenous communities are now closely linked with nearby cities, while others remain relatively isolated. All of these communities are striving to maintain traditional cultural practices within the context of modernization, especially for natural resource management. The strugg le to maintain cultural integrity in the face of economic pressures is made more difficult by the complex history of conquest, revolution, and social injustice.
A closer look at this history exposes ways in which changing cultural values, traditions and economies, affect local strategies of resource use and management. These social, political and historical forces have a prominent affect on sound forest management. Forest management activities in Sierra Juarez shows exploitative practices by Fabricas de Papel Tuxtapec (FAPATUX), a national paper manufacture in 1956, FAPATUX acquired a 25 year concession to harvest the communal forests of Ixtlβn. Despite the success of the communities in working with FAPATUX and influencing the management of the communal lands, they wanted greater control over the lands and sought to prevent the continuation of the concessions. Since then, communal forest management has sought to achieve two primary goals: 1) to provide economic returns and employment, and 2) to steward the land responsibly and sustainably. Their management plans have evolved to include the manipulation of standard silvicultural procedures and their integration with traditional agricultural and non-timber forest product cultivation. Through an analysis of barefoot silviculture and traditional medicine, this papers aims to shed light on the complex social, political and historical forces affecting land use management in Oaxaca today.
The White Coat Effect
The state of Oaxaca is one of the regions in Mexico that has best retained traditional knowledge about medicinal plants. Cervantes Servin et al. (1990) registered 101 medicinal plants (66 wild and 35 cultivated) in the Ocotlβn District in Oaxaca. In Chimalapas, the traveling herbalist working with Maderas del Pueblo, a local Oaxacan NGO, knows at least 90 species of medicinal plants. There is still a vast knowledge base on medicinal plants. However, local people's use and knowledge of plants is threatened, particularly as a growing number of people turning to ‘modern’ medicine. In this paper we refer to this transition as the white coat effect.
The role of the travelling herbalist is a traditional and important one in village life in Oaxaca (Messer, 1978). Traditionally, curanderas/os were the most important healer in the communities of various indigenous groups in Mexico. However, today there are relatively few practicing curanderas/os. In Chalchijapa, there are no curanderas/os, a crucial missing link in maintaining faith in herbal remedies. The loss of authority figures, such as the curanderas/os and midwives, is accelerating reliance on Western medicine. Doctors trained in Western medicine and wearing clean white coats, pharmacies displaying shelves of shinny packages of pills, and newly built clinics, all act as symbols of authority and serve to legitimize western medicine. Chalchijapa, like many other villages in Chimalapas, is depending more and more on Western medicine. A private doctor, who occasionally visits from the nearby town of Matias Romero, dispenses shots, pills, and creams to villagers. For emergencies, the villagers must travel to Matias Romero - two to three hours away by car on dirt roads. However, this situation will soon change, as modernization efforts aimed at improving medical care have sponsored the building of a new Western style medical clinic.
In Chalchijapa, Chimalapas, villagers explained that in 1967, a major road was built connecting Santa Maria to the outside world. Since then, traditional medicinal systems have undergone tremendous changes. Campesinos now give their children Western medicine, an indicators of the substantial cultural change and “modernization.” The two Zoques said that Western medicine is referred to as “doctor's medicine.” This name appears to symbolize the authority that Zoques attach to Western medicine. In Santa Maria, Western medical clinics provide service to the whole community. Many residents of Santa Maria, however, criticize doctors in the state-run hospitals for only prescribing the medication that they happen to have on hand at the time. Consequently, people who can afford to go to private Western doctors usually do. Despite the increasing popularity of Western medicine, most women still treat their family members' common illnesses with herbs. However, without a permanent locally-based curandera/o in the larger town of Santa Maria to cure the people there are displaying a general trend toward reliance on Western medicine. Few people in the town still trust herbal remedies for anything more than the common cold. As a result, traditional medical practices are quickly disappearing.
Community Based Management and NGO Collaboration
Maderas del Pueblo is a Oaxacan non government organization (NGO) with approximately ten years of experience working with communities in the Chimalapas region. The NGO's programs extend over a range of issues, from silviculture to health and nutrition, to social organization. The people of Chimalapas and Maderas del Pueblo have adopted a position of ardent opposition to the Mexican government's proposal to create a Biosphere Reserve in Chimalapas. Isaac Matus (pers. comm. 1996), the coordinator for technical monitoring and evaluation for Maderas del Pueblo, believes that all official reserves in Mexico are failures because they are not designed with the needs of local people in mind and are administered from the top down. Maderas del Pueblo supports the creation of a Campesino Ecological Reserve in Chimalapas, instead of a nationally sponsored Biosphere Reserve, which would emphasize the participation of local people in the management of their natural resources in order to best promote the conservation of the region's environment. This is one of the most important projects the NGO has undertaken to secure the autonomy of the communities. Strengthening the autonomy of local people is viewed as a critical factor in reversing the decline of indigenous cultures (Halffer, 1994). In addition to devolution and decentralization of decision making for conservation objectives, there is a need for integrative silvicultural systems that are adaptive, giving communities the flexibility to respond to failures and ever-changing conditions. Community forestry in this part of the world has fostered a great sense of responsibility and better stewardship of the land through the manipulation of standard silvicultural procedures and their integration with traditional agricultural practices. These community-based management approaches with integrative or “barefoot” silvicultural systems better integrate indigenous knowledge and traditions in management decisions.
Barefoot Silviculture: Integrative and Adaptive Systems
Sound management has traditionally been evaluated by the development of a silvicultural prescription that combines a sequence of treatments into a coordinated plan aimed at meeting a particular management objective. The barefoot silviculture prescription similarly integrates a sequence of management treatments but also justifies the treatment choices based on specific ecological, managerial and social grounds. Usually sound forest management is described by an array of traditional silvicultural practices, most of which are implemented in order to cultivate pine in Ixtlβn and neighbouring communities of the Sierra Norte. This array of silvicultural practices are broken into two categories that yield even and uneven aged stands. Even-aged systems include clear cutting, seed tree and shelterwood systems while un-even aged describes single tree and group selection systems. However these terms are deceiving, alluding to age and trying to infer stand structures. Silvicultural choices should be thought of as determining what kind of stand development process or stage of natural succession is most desirable in a given situation. These choices are made among the stand structures and processes to start or to alter them after they have been initiated. The artificial dynamic equilibrium between an indigenous culture and its environment has been achieved through the use of prudent barefoot silvicultural systems, not defined by age but more by vertical structures. These systems may be less stable than nature's ecological equilibrium but ought to be more favorable from the standpoint of the integrated effect of all socioeconomic factors. A new set of structural definitions are thus needed to define the vertical stand structures necessary for many non-timber forest products essential to indigenous cultures and traditional medicinal systems. These structural definitions will make it easier to document barefoot silvicultural systems and the inherent ability that indigenous peoples have developed for distinguishing between stand develop patterns. These structural definitions are divided into single cohort and multicohort stands.
Single Cohort Stand Development
A given aggregation of trees of a single age class or cohort proceeds from birth to death through a sequence of development stages (Oliver and Larsen 1996). These must be recognized if understanding of stand dynamics is to be used to cultivate on-timber forest products essential to indigenous cultures and traditional medicinal systems. This understanding is critical to achieve management objectives by imitating, guiding, or altering natural processes in barefoot silvicultural treatments.
The first stage in stand development (see graphic 2.3) is called stand initiation, describing the unit of growing space and the cohort of trees that become established in it (or preexisting smaller ones that expand into it). The second stage of stand development is stem exclusion, where trees start to compete with one another and the more vigorous trees usurp the growing space of weaker ones that die from biotic and abiotic effects. Unless some disturbance breaks up this stand and starts a new initiation phase, growth will continue with time until an understory is developed. This stage is called the understory reinitiation. In this stage, many opportunities exist to cultivate an understory of shade tolerant non-timber forest products that take advantage of small vacancies in the growing space. Unless something happens to replace most of the stand, older trees gradually die and replace by younger stand classes turn this single cohort stand into a multicihort stand. This leads gradually into an old growth stage. This process of stand development is shown in Figure 2.3 below (Oliver and Larsen 1996).
The integration of non-timber forest products within single cohort stand development depends on the vertical structure necessary for the product in question.
In the diagram, two stand structures from single cohort origins demonstrate stand development with and without differentiation with completely different vertical structure. With single cohort systems that manage stratified mixtures, development processes must be studied carefully to determine the appropriate integration with cultural systems. The development processes of stratified mixtures of species takes place with differentiation of trees according to height is into different horizontal strata or stories, one above the other, with one species or a group of species in each stratum. The differentiation is not simply into crown classes within a single canopy stratum as in single cohort stands without differentiation and disturbances. With the inclusion of disturbances, stand development processes will follow a pattern discussed under multicohort.
Case of Single Cohort Stand Development: Seed tree system
The seed tree system has historically been an underused and under appreciated silvicultural system in Mexico. In 1983, 56,000 ha (less than 3% of Mexico's mixed conifer forests) were under even-aged management incorporating this regenerative method with intermediate thinnings (Snook and Negreros, 1986). Today, the numbers are likely significantly higher because communities have seen the greater profitability of this treatment and its success in naturally regenerating pine. Limiting the number of entries into a stand and concentrating management activity in a relatively small area on a year to year basis are two factors which make seed tree systems so profitable. In addition, Negreros and Snook (1984) found that pine annual volume increments were 2.5 times greater in even-aged sites than in selectively cut uneven-aged forests.
In Ixtlβn, a typical seed tree cut will leave from 10–30 large trees per hectare on the site after the harvest for seed dispersal. Post harvest site preparation is frequently carried out similarly to ecosystems in the United States (Graney and Kitchens, 1983, Roy, 1962, Mielke and Kimmey, 1942). Piling and burning is used heavily by some communities because it favors intolerant pines like Pinus patula, Pinus pseudostrobus, and Pinus douglasiana (all commercial species). Other fire adapted pines will also gain a competitive advantage over hardwoods: Pinus leiophylla and Pinus oocarpa which resprout from the root collar as saplings; Pinus patula and Pinus oocarpa which have serotinous cones; and Pinus montezuma which exhibits a grass stage early in life. Once sufficient regeneration has been achieved, ideally thousands of seedlings per hectare will become established in the opening created by the harvest, the seed trees can be removed. During a forty year growing period, intermediate thinnings were necessary to redistribute growing space for maximum diameter growth at 500–750 trees per acre, yielding trees 50 cm in diameter and of good commercial form. Those which were not suitable for commercial harvest were stacked and cultivated with mushrooms. This integration of an intermediate treatment with non-timber forest products makes pre-commercial thinnings more viable in otherwise difficult financial situation. This comes from an understanding of single cohort stand development and is thus considered a kind of barefoot silviculture.
The timing of the seed tree removal is a topic of debate in Ixtlβn. While the seed trees occupy only 10–15% of the total available crown area they will slightly reduce the amount of solar radiation reaching the forest floor. This has the potential of reducing the growth rate of the newly established seedlings. However, the residual trees are free of competition and growing at an increment rate of one cm/year. The relevant question is: when does the value added due to growth of the residuals fall below the value lost due to suppression of the seedlings? Typically, with thousands of seedlings on the forest floor, the loss should be negligible. In fact on poor sites of southern exposure, even the more intolerant species may benefit from the protection of a few trees during the first few years of establishment when seedlings are particularly vulnerable to desiccation. An additional concern is the amount of damage that will be caused to the regeneration by the removal of the residual trees. One community compromises by removing all but three of the seed trees per hectare at ten years to avoid competition with the younger seedlings. The three trees left per hectare act as insurance against failure of the existing natural regeneration.
Some communities are hesitant to rely too heavily on this system because as in all silvicultural systems reliant on natural regeneration, there is room for failure. The communities have dealt with this risk in a number of innovative ways.
Seed tree cuts are riskier than selection cutting or group selection because competing vegetation in the form of oaks can maintain control of the site as seen in other regions (Graney and Kitchens, 1983, Roy 1962). The short term costs of regeneration failure in a seed tree system are high because manual replanting is required. The other systems are not likely to incur any short term costs but over the long run many of these sites will convert to hardwood and conversion back to pine will be very costly. Many communities conduct enrichment plantings and control competing vegetation by hand if sufficient natural regeneration has not been achieved within three years of the harvest. In Ixtlβn a new initiative has started which will incorporate traditional agricultural practices within forestry operations. After three years the sites are evaluated for regeneration success. On sites where regeneration is absent the opportunity to utilize the area for agricultural production will be offered to the community. The farmer who accepts the land will have three years to cultivate it usually for maize production. During the site preparation all non-pine species are removed and significant amounts of bare mineral soil exposed providing a good opportunity for natural regeneration to become established over the next three years. If at the end of the period of cultivation sufficient natural regeneration still has not been established the area can easily be planted without concern about competing hardwood vegetation since it has been controlled during the previous three years (Cardenas, 1996). Another community used the regeneration period for planting potatoes so that farmers could actively tend to their seedlings while cultivating their crop. Such opportunistic use of existing growing space benefited the community through additional agricultural production and provided incentive to control hardwood competition (Cardenas, 1996). These systems are not original since they closely resemble taungia systems of plantation establishment, but they have been significantly modified to meet the needs of the community.
Case of Single Cohort Stand Development: Clearcut-plantation system
Plantation silviculture (a single cohort cycle of clear cutting and replanting a desired species) does not currently exist in Oaxacan communities. An analog of this system does however exist in some restoration zones. Large areas of abandoned agricultural land are being reforested by planting commercial species like Pinus patula on a 2 meter spacing, yielding a density of 3600 trees per hectare. Other commercial species like Pinus acahuite and Pinus pseudostobus are being mass produced in Sierra Norte nurseries for plantation purposes. Competing brush species are either outgrown by the fast growing pine or eliminated by manual intervention. Pruning and intermediate thinning regimes have been discussed to increase commercial yield of these plantations. With shifting agriculture continuing to be practiced in this region mature second growth forest will be clear-cut to establish agricultural fields. At abandonment these areas will likely be replanted as a plantation with locally produced nursery stock.
Forty years after planting, the foal crop of 200–300 high volume and high value trees is harvested. Logs are left lying horizontally (parallel with slope contours) so as to reduce soil erosion potential during extraction. It is anticipated that these areas will be regenerated according to the seed tree system at the start of the second rotation and clearcutting reserved for the establishment of agricultural fields.
Multi-Cohort Stand Development
When stands develop with a large number of small disturbances (including harvesting events), new cohorts may start to develop in the openings thus created. This creation and development of such stands makes management more complicated even if they are purely one species. In diverse ecosystems like those in Oaxaca, most multicohort stands are actually mixtures of species with different development rates. Since multicohort stands are defined by different age groups, it is important to be able to recognize the difference in development and resultant stand structures for its integration with cultural knowledge systems. Differences in age distribution are most easily recognizable in mixed stands composed of species with different rates of height growth so that each cohort has a recognizable pattern of dominant and suppressed species in each stratum of the crown canopy. However, single cohort stands of tree species usually segregate into different canopy strata and exist as stratified mixtures so it may be possible to confuse the two. In barefoot silviculture, indigenous cultures have the opportunity to see stand develop over time, thus distinguishing between stratified mixtures that originate from single cohort origins and those that develop into multi-cohort mixtures (through patterns of ecological disturbances). Primary to this understanding is a fundamental knowledge of which species of differing ecological status occupies each different strata in the crown canopy. In general, many indigenous groups have this understanding of these two development patterns and work within them to gain some sort of benefit. It is necessary to document the ways that local people distinguish between these two stand develop patterns (as they represent themselves on the landscape similarly). This type of indigenous knowledge is a fundamental principal of barefoot silviculture and the adaptation of standard silvicultural systems for integrating cultural knowledge on non-timber forest product cultivation.
Traditionally in silviculture, in order to identify cohort development patterns diameter was considered the most appropriate measure (with some inference of age from diameter growth). It is now apparent, that the most accurate assesment of age-class structure of a stand comes from the actual ring counts. Although this is possible with many of the conifers in Sierra Norte, this is not possible with many of the hardwoods in the Chimalapas area. In the following diagram, it is seldom reliable to depend on diameter criteria until direct age has been determined through representative counts typical of that locality and with consideration of the pattern discussed in single-cohort development.
Case of Multi-Cohort Stand Development: Selection cutting
In this region of Mexico, selection cutting as conducted by FAPATUX was applied exclusively to pines like Pinus patula. Typically reducing the basal area in a mixed species stand from 64% to 54% over a twenty year period (Negreros and Snook 1984). Under current management in Ixtlβn stands managed under the single tree selection method are entered every ten years to conduct density reductions. Maintaining a residual growing stock of around 49.4 MBF per hectare is achieved by removing 20–25% of the trees. The removal of trees alters the micro climate allowing for more regeneration to take place. The diffuse pattern of timber removal ensures that all ages of trees will be intermixed creating a multiple story. This pattern has some aesthetic and wildlife attributes that stands in protection zones will not achieve. The administrative advantage is there usually is no need for expensive site preparation or planting. Theoretically regeneration is reliable and more or less automatic as new trees are simply recruited from the reservoir of saplings in the forest understory. There are usually more than enough to choose from, although tolerant trees have an advantage. This type of regeneration also means that trees from all size classes must be removed during the harvest, so as to create the ideal distribution under a regulated system (14% in each size class for this stand).
This multi-cohort silvicultural system can achieve sustained yield from a single stand of trees. A number of potential problems exist for single tree selection harvesting. These issues must be addressed before single tree selection can be considered a viable management option. Besides the threat of high-grading, there exists a problem with pine regeneration when selection cutting is practiced. If gaps are not large enough to provide the micro climate for shade intolerant pines (accept for Pinus ayacuite which is shade tolerant), then oaks will come in to the stand. If this occurs it may be necessary to further open the canopy to promote pine regeneration. Many pines also require bare mineral soil for germination. If the logging operation does not disturb the duff and expose bare mineral soil, pine regeneration may not be successful. Foresters from the region claim however, that this is not a problem as soil scarification does occur. If no regeneration occurs, the plan is to return to the site in ten years for further cutting. Negreros and Snook (1984) studied pine regeneration in the Sierra de Juarez region and found that low-intensity selective cutting does not stimulate pine regeneration to provide for adequate replacement of harvested trees. Despite these concerns, selective cutting is seen as an appropriate silvicultural system because it maintains a forest canopy with vertical structure necessary for many wildlife species (Hunter 1990). This is also the vertical structure necessary for integration with non-timber trees that can provide fruits, nuts, medicines, condiments and other products. Single cohort silvicultural systems, especially those reliant on single tree selection are especially valuable for developing multi-storied tree gardens as demonstrated here.
Case of Multi-Cohort Stand Development: Group selection
Some communities within Sierra Norte use a group selection system on a 60 year rotation. This system is typically used in more diverse areas with the primary objective of maintaining a healthy mix of pine and oak. These diverse areas tend to be at lower elevations on more humid sites, usually at the upper boundary of the cloud forest. Group selection is used to maintain the appearance of a contiguous forest canopy while promoting the more valuable pine species. These communities are aware of the pine regeneration problem inherent with single tree selection and the difficulty of achieving a single species stand through natural regeneration. They therefore manage with the intent of maintaining an equilibrium between natural species diversity and promoting commercial valuable species. As with single tree selection, the cutting cycle is ten years, extracting 200m3/ha per entry. Many opportunities exist with cohort harvesting for non-timber forest product cultivation and harvesting including honey bee and butter fly collections.
By cutting small groups of trees instead of scattered individuals, the amount of direct sunlight can be increased to the point where regeneration of shade intolerant species (both woody tree and non-woody forest products) can occur. This group selection method mimics what happens naturally when a root disease center or a bark beetle infestation develops, creating small gaps in the forest. It is therefore probable that most shade intolerant species could successfully be managed by small patch cuts of one hectare or less. This management strategy is called mosaic cutting and falls between the traditional group selection cuts and clear cutting in terms of the size of the cut and the intensity of the disturbance. This method will improve growing conditions for many non-timber forest products that depend on full sunlight for their competitive advantage, while still retaining the more or less closed-canopy appearance of the forest as a whole. Because of its aesthetic appeal and high yield potential it seems likely to become a more popular practice in Oaxaca.
Further Opportunities for Integration
There are further opportunities to define the vertical stand structures necessary for many non-timber forest products essential to indigenous cultures and traditional medicinal systems. These structural definitions will make it easier to document barefoot silvicultural systems and the inherent ability that indigenous peoples have for distinguishing between stand develop patterns. The following table demonstrates such opportunities that should be studied and documented further:
The choice between growing trees in single cohort or multi-cohort stands will ordinarily depend on particular management goals and constraints. Single and multi-cohort stands are terms used to describe stand structures and the kinds of stand development processes (or stage of natural succession) most desirable in a given situation. These choices are made among the stand structures and processes to start or to alter them after they have been initiated. Many smaller communities might consider the tendency for selection cutting to favor shade-tolerant species a trivial concern, especially when measured against the numerous financial advantages of the selection system (including the presence of many herbaceous NTFP species that require continuous forest cover). However, in the Sierra Norte, the lack of commercial markets for oak wood may convince communities otherwise (Negreros and Snook 1984). For communities heavily tied to forest industries, conversion to tolerant species can be a serious problem. Non timber forest products and the stand structures that promote them need to be analyzed carefully to determine their role in alleviating the dependency on timber. Because the cost of conversion back to a commercial timber species is frequently very high and there is usually no commercial market for the invading species, non-timber forest products may be the only way to generate income during the conversion process. Barefoot silvicultural systems which integrate indigenous knowledge of non-timber forest product cultivation need to be better documented so that lesson learned may be applied to other communities facing the same shortages in commercial timber stocks.
Barefoot silviculture allows indigenous peoples to develop their own management plans and silvicultural techniques to suit their cultural needs. The artificial dynamic equilibrium between an indigenous culture and its environment has been achieved through the use of prudent barefoot silvicultural systems sometimes develop over thousands of years of trail and error. This equilibrium is less stable than nature's own ecological equilibrium but more favorable from the standpoint of the integrated effect of all socioeconomic factors. Barefoot silviculture is thus based on the premise that silvicultural systems can be built to not only promote ecological and economical sustainability, but also cultural sustainability. The success of the management plans and the current barefoot silvicultural systems has yet to be evaluated in Oaxaca (other than this endeavor). The array of silvicultural systems utilized in these communities demonstrate that the autecology of the species being managed and the edaphic differences between sites (as well as the land use history) are all being considered. In addition, the manipulation of standard silvicultural procedures and their integration with traditional agricultural practices indicate that the management of the timber resources in Oaxaca will continue to be a dynamic process. Having the flexibility to respond to failures and ever-changing conditions will ensure that Oaxaca will adapt its management and silvicultural systems over time to achieve its objectives while maintaining its cultural integrity.
Figure 5.2 Schematic stages of stand development following major disturbances. All trees forming the forest start soon after the disturbance, however, the dominant tree type changes as stem number decreases and vertical stratification of species progresses. The height attained and the time lapsed during each stage vary with species, disturbance, and site. (Oliver, 1981.) (See “source notes.”)
|S i n g l e C o h o r t||M u l t i p l e C o h o r t|
|C o n v e n t i o n a l N a m e s o f S y s t e m s||C l e a r c u t|
O v e r s t o r y r e m o v a l
S e e d t r e e
S h e l t e r w o o d
|S i n g l e t r e e s e l e c t i o n|
G r o u p s e l e c t i o n
F e m e l
M o s a i c
|P o t e n t i a l A d a p t a t i o n s w i t h t r a d i t i o n a l p r a c t i c e s||A g r i c u l t u r e|
Gr a z i n g
M u s h r o o m c u l t i v a t i o n
B a m b o o c u l t i v a t i o n ( i n A s i a )
E a r l y s u c c e s s i o n a l m e d i c i n a l s
B u t t e r f l y c u l t i v a t i o n
H o n e y
|S h a d e c o f f e e|
G r a z i n g
M u s h r o o m C u l t i v a t i o n
O r c h i d / B r o m i l i a d
S o m e l i a n a s
L a t e s u c c e s s i o n a l m e d i c i n a l s
|N T F P S h a d e R e q u i r e m e n t s||S h a d e I n t o l e r a n c e|
S u n - l o v i n g
|S h a d e T o l e r a n c e|
S u n - A v o i d a n c e
Figure 21.1 Structure of a multi-story tree garden as used throughout the tropics. Fruits, nuts, medicines, condiments, and other products are harvested from different strata.
Figure 2.2 Typical examples of five different kinds of stand structure show the appearance of stands in vertical cross section and corresponding graphs of diameter distribution in terms of numbers of trees per unit of area. The trees of the first three stands are all of the same species. The fourth stand consists of several species, but all of the same age, and the fifth stand has trees of two different age classes.
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Meinecke, E.P. 1914. Forest tree diseases common in California and Nevada - a manual for field use. USDA Forest Service, Washington D.C.. 67p.Messer, E. 1978. Prehistory and human ecology of the Valley of Oaxaca. Ann Arbor: University of Michigan Press), 44 p.
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Glossary of Terms used in this Paper:
Cohort: each aggregation of trees that start as a result of a single distrubance.
Cutting cycle: the treatment of stands periodically with each period being called a cutting cycle. The multi-cohort stand would have as many age classes as there were cutting cycles in the rotation.
Even-aged: narrow aggregation of the range of tree ages within a stand; or all trees are of the same age or at least of the same cohort.
Gap and patch dynamics: patterns of establishments and subsequent development of vegetation in all vacancies of any size in the growing space.
Growing space: sum of the factors necessary for growth; available space for plant growth above and below ground.
High-grading: process by which the best trees have been cut leaving the worst quality behind. Best species and largest stems are taken first leaving poor seed stock for future generations
Multistory tree gardens: small plots that are characterized by a large variety of tree species, shrubs and vines but with few or no herbaceous crops.
Shade intolerance: species with a very high compensation point, meaning that much light intensity is necessary for the leaves to sustain themselves.
Shade tolerance: the ability to survive in more shaded conditions than other plant species, since their leaves can photsynthesize enough at lower light intensities to stay alive.
Shade tree/crop combinations: two storied stands with one or more species of tall trees growing above an herbaceous, shrub, or small tree crop.
Understory: the lowermost strata of shrubs or herbaceous vegeation.
Uneven aged: contains at least three different age classes intermingled intimately on the same geographic area.
M. David GANZ
OAP-FAO, Kasetsart University, BANGKOK
Étant donné que la région de Oaxaca est l'une des régions biologiquement les plus diversifiées des tropiques, la principale difficulté consiste à réaliser l'équilibre entre l'exploitation durable de la forêt et la préservation de la diversité biologique, ce qui est tout particulièrement difficile pour des communautés villageoises ayant des ressources limitées, du point de vue économique comme du point de vue technique. Les plantes médicinales et les autres produits forestiers autres que le bois sont particulièrement vulnérables aux régimes de récolte excessifs. Le document étudie en détail les activités d'aménagement forestier des communautés de deux régions de l'État de Oaxaca au Mexique. Le cas des Chimalapas et de la Sierra Del Norte est étudié pour illustrer la façon dont les valeurs culturelles, les traditions et l'économie influent sur les stratégies locales d'exploitation et de gestion des ressources. Par une analyse de la sylviculture rurale traditionnelle et de la médecine traditionnelle pratiquées dans ces deux régions, le document vise à mettre en évidence le réseau complexe de forces sociales, politiques et historiques qui sous-tend l'aménagement du territoire à Oaxaca aujourd'hui.
Le document fait aussi ressortir la nécessité d'opter pour des systèmes de sylviculture intégrés et susceptibles d'adaptation, qui donnent aux communautés la souplesse voulue pour réagir en cas d'échec et face à des conditions toujours changeantes. La foresterie à l'échelon de la communauté dans cette région du monde a favorisé un sens aigu de la responsabilité et une gestion plus avisée des terres en adaptant des façons sylvicoles courantes et en les intégrant aux pratiques agricoles traditionnelles. Ce mode de gestion à partir de la communauté intègre mieux le savoir et les traditions autochtones dans les décisions concernant la gestion. De plus, la participation des autochtones à l'élaboration de leurs propres plans de gestion et de leurs techniques sylvicoles est importante non seulement pour promouvoir l'exploitation durable du point de vue écologique et économique, mais aussi la pérennité culturale, essentielle à la survie de la médecine des autochtones, de leurs valeurs et de leurs traditions.