Forest governance can be described as the modus operandi
by which officials and institutions acquire and exercise authority in the management of forest resources. Good forest governance is characterized by predictable, open, and informed policymaking based on transparent processes; a bureaucracy imbued with a professional ethos; an executive arm of government that is accountable for its actions; and a strong civil society that participates in decisions related to the sector [1
In 2003, the Mexican federal government published the Law for Sustainable Forestry Development (LSFD) with the primary objective of regulating and promoting the management, restoration, and conservation of forest ecosystems in the whole country [3
]. This law authorizes timber harvesting in old-growth forest lands, and the establishment of commercial timber plantations in deforested lands. In 2005, the government published the regulation of this law [4
]. The regulation determines the harvest potential based on specific minimum biomass/structural reference values that reflect the maturity of forest stands.
The definition of acahual
(term used in Mexico for secondary forest) is only mentioned in the second point of the regulation and considers the native secondary vegetation that grows spontaneously in tropical forest lands that have previously been used for agriculture or cattle grazing. At this point, the regulation states that: (a) in evergreen or semi-evergreen forests, secondary vegetation is considered as those stands with less than 15 trees per hectare with a diameter at breast height (dbh) greater than 25 cm, or with a basal area less than 4 m2
/ha; and (b) in dry forests, secondary vegetation is considered as those stands with less than 15 trees per hectare with dbh greater than 10 cm, or with a basal area less than 2 m2
In Mexico, the dominant vegetation communities are temperate forests, mostly Pinus
]. Therefore, it is possible that the LSFD and its regulation were developed based on the characteristics of these ecosystems, which are also the target of most of the commercial forestry in the country (65.3%) [6
]. However, in the view of scientists and stakeholders from the Mexican tropical areas, this legislation is not sufficiently flexible to allow regional variations in best practice that would encourage innovation and experimentation. This is the case in the Yucatan Peninsula, an important source of tropical forest and non-forest products for the rest of the country. The authorities, ecologists, and landowners of this region have initiated a dialogue to review the implications of the LSFD for forest management, restoration, and conservation.
The Yucatan Peninsula encompasses the largest expanse of seasonal deciduous semi-evergreen tropical forest in Mexico, forming a complex and biodiversity-rich environmental gradient between the drier north of the peninsula and the humid Peten region in Guatemala [7
]. Forest surveys performed in the Yucatan Peninsula have demonstrated the importance of the traditional slash-and-burn agriculture for forest regeneration, the recovery of soil fertility and the supply of secondary forest products (e.g., wood, construction materials, textiles, food, medicines, and tanning) that are vital for its rural economy [8
]. In addition, tourism development in the Mexican Caribbean has increased the demand for palm leaves and round wood from secondary forests (<25 cm diameter at breast height, dbh), which are widely used for the construction of lodges and play a key role on the marketing of this tourism destination [10
The basis for traditional secondary forest use and management in the Yucatan peninsula is tropical swidden agriculture (variously called shifting cultivation, slash-and-burn agriculture, or, in Mesoamerica, the milpa). Like most other tropical swidden systems, that of the peninsular Mayans centers on felling primary or secondary forest, burning the dried cuttings, and planting selected species in the clearing. Mayans plant and harvest a milpa for two to five consecutive years, then plant the area in tree crops and extracts fruit, rubber, and cordage as the fallowed area regenerates into secondary forest. When regrowth reaches a height of four to seven meters (usually within five to seven years), they clear and burn the area for a second round of cultivation, or allow it to regenerate into secondary forest, a process which requires approximately twenty years of fallowing [8
In this study, we evaluated the accuracy of the biomass/structural reference values of the LSFD and its regulation for differentiating secondary from old-growth forests, and assessed whether they may be preventing the traditional use, management, and restoration of secondary forests and threatening the conservation of biodiversity in the Yucatan Peninsula. We also present our results in the light of an ongoing debate between the authorities, scientists, and practitioners of the Yucatan Peninsula to assess the implications of the current legislation on forest management, restoration, and conservation.
2. Materials and Methods
2.1. Study Area
The implications of the LSFD for forest management and conservation were assessed in the context of the Calakmul Biosphere Reserve (CBR), which is located in the state of Campeche, Yucatan Peninsula, Mexico (Figure 1
). The CBR covers an area of 723,185 ha and is the largest tropical reserve in the country. Its topography is flat and smooth and its altitude varies from 260 to 385 m above sea level [11
]. The climate is warm subtropical with a mean annual temperature of 24.6 °C and a mean annual rainfall of 1076 mm. Soils are shallow, calcareous, and highly permeable because of a high organic matter content and an underlying limestone bedrock [9
Semi-evergreen forests cover most of the surface of the reserve. These are forests with trees reaching 15–25 m in height, 25%–50% of which lose their leaves during the dry season. The flora of Calakmul includes ~390 genera and 1500 species, 10% of which are endemic. The representative tree species of this type of forests are guayacán (Guaiacum sanctum
), jobillo (Astronium graveolens
), chicle (Manilkara zapota
), ramón (Brosimum alicastrum
), chakah (Bursera simaruba
), and guarumo (Cecropia obtusifolia
Map of the study region in Southeastern Mexico, showing the location of the 50 forest plots sampled.
Map of the study region in Southeastern Mexico, showing the location of the 50 forest plots sampled.
Land tenure in the reserve is 49.6% communal, 48.4% property of the nation, and 2% privately owned [13
]. The people who live within the reserve came from the states of Tabasco, Veracruz, Chiapas, and Michoacan, and their main activities involve slash-and-burn agriculture, cattle grazing and the harvesting of secondary forests [7
]. These activities are complementary within the traditional (indigenous) system of shifting cultivation, in which managing forest fallows and second-growth forests is considered as a component of an integral agricultural system that relies on forest resilience [8
Between 2011 and 2013, representatives of the CBR funded and convened a total of 12 workshops to promote a multi-sectorial dialogue aimed at evaluating the potential implications of the LSFD and its regulation for traditional secondary forest management, as well as for the conservation of the region’s biodiversity.
The participants of the workshops included representatives of the three broad groups that have a stake in ensuring good governance in the forest sector: (a) government: sub-national and national representatives of forest agencies and other departments and ministries; (b) civil society: representatives of community groups and social and environmental non-governmental organizations; and (c) the academic sector, represented by research specialists in forest ecology and management.
Representatives of the CBR encouraged scientists from El Colegio de la Frontera Sur to evaluate the accuracy of the forest ecological criteria stated in the regulation of LSFD. For this purpose, we conducted: (1) a review of the forest successional studies performed in the study region and in other similar tropical forests; (2) a comprehensive field sampling on forest successional development in the study area; and (3) an evaluation of the potential risks for biodiversity conservation that could stem from the implementation of the LSFD and its regulation.
2.3. Field Sampling
To assess the reliability of the biomass/structural reference values established by the regulation of the LSFD for differentiating old-growth from secondary forests in the context of the semi-evergreen tropical forests of the Yucatan Peninsula, we performed vegetation assessments in the CBR using a chronosequence approach. Field data were recorded during plant surveys conducted during 2012. The surveys were based on a stratified random sampling design with a total of 50 sampling plots in five stages of forest succession (10 plots per age class), i.e., 3–6, 9–11, 14–16, 19–21, and more than 50 years with no evidence of recent clearing, burning, or extractive human activities. The local authorities and informants from local communities helped to identify the tree species present in the plots, their main uses, and the land-use history of the different sites sampled.
After the identification of forest stands at different fallow intervals, we sampled 10 plots of 500 m2
per age class. Using calipers, we measured all stems that were >2 cm dbh. The source of the species regeneration (seed or regrowth) was also recorded in a field notebook. Samples of the specimens were collected and deposited in the herbarium of El Colegio de la Frontera Sur, Chetumal headquarters. For species identification, we used dichotomous botanical keys, existing floristic lists for the study area [14
], and sample contrast with herbarium specimens.
2.4. Data Analysis
Differences in basal area and stem density as a function of age were tested, via one-way analysis of variance (ANOVA). Tukey’s multiple comparison procedure was applied if statistical differences were detected (p
< 0.05). To comply with normality assumptions prior to ANOVA, stem density was log10
]. Depending on species basal area across forest age classes, we classified species into successional groups, such as pioneer, persistent non-dominant, persistent dominant, and late-successional species [16
]. We performed all statistical analyses and plots using the IBM SPSS Statistics processor, version 21.0.
The current forest structural reference values established by the regulation of the Mexican LSFD are controversial and do not apply to the tropical forests of the Yucatan, as they do not serve to differentiate between young regenerating, secondary, and old-growth forests appropriately. Moreover, the LSFD and its regulation disregard the traditional harvesting of secondary forests for rural construction, thus forcing small landowners to comply with management plans as if they were major timber producers. Although the stump regrowth of persistent species is important for forest regeneration after agricultural land use in the Yucatan peninsula, the diversity and coexistence of species from different successional groups is maximized in intermediate successional stages (about 20 years after abandonment). Late-successional species are particularly vulnerable to increased deforestation and the systematic clear cutting of young secondary forests, because of the specific conditions that are required for their regeneration, which can only be achieved through long fallow periods (>20 years). The facilitation of participatory processes between the different stakeholders involved in local forestry allowed the review of the major problems of the LSFD and its regulation, as well as the implementation of a field sampling to evaluate the accuracy and implications of the forest ecological criteria of these legal instruments. To adjust the existing reference values, as well as to develop a consensual concept of secondary forests, both in the regulation and in the law itself, modifications should be accompanied by accessible and well-documented procedures, and by fiscal incentives to encourage voluntary investments in forest management and restoration.