Cuauhtémoc Sáenz-Romero 1
México has one of the largest biodiversities in the world, in particular of the genus Pinus. However, several Pine species and locally adapted pine populations are endangered by a high rate of deforestation. Although there is a large governmental reforestation programme of about 200000 ha/year, its success is very limited, because the seedling survivorship is poor: 35% for the first year. We discuss the causes of this poor survival rate: some sites are too eroded already to support tree seedlings, there is an inadequate selection of species and provenances, reforested sites in many cases are insufficiently protected, sometimes planting operations are too late in relation to the rainy season, and frequently seedlings are of poor quality. We suggest some actions that would improve the survival rate of seedlings (besides a substantial budget increase): exploration of new strategies for ecological restoration depending on the site's level of degradation, research on techniques for endemic species propagation (for example nitrogen-fixing trees and trees of genus Bursera) and for new methods of nursery production, establishment of species and provenance field tests, delimitation of seed zones as guidelines for deciding seed and seedling transfers, and establishment of gene resource management units, before current forest fragmentation by deforestation makes the losses of valuable forest genetic resources irreversible.
México is center of diversity of the genus Pinus, with the world highest diversity of Pinus species (Styles 1993, Farjon and Styles 1997) and large donor of forest tree germplasm for tree plantations worldwide (CAMCORE 2000). However, forest genetic resources at present are being decimated due to change of use of land to agriculture and grazing and by the effect of forest fires and illegal logging. Deforestation is estimated in 668,000 ha/year or 1.29% of forest cover per year (Masera et al. 1995, Masera et al. 1997). Deforestation endanger not only very rare and endemic Mexican pines species, such as Pinus culminicola, P. maximartinenzii, P. rzedowskii and P. pinceana, (Perry 1991, Styles 1993), it also endanger locally-adapted populations of species with widespread distribution and high economic value, such as P. montezumae, P. patula and P. pseudostrobus. Mexican federal and state government have in place a large reforestation program of approximately 210,000 ha/yr to counteract the effects of deforestation (CONAFOR 2002). However, seedlings planted under such program have a very low surviovorship rate: about 34 % for the first year after planting (Masera et al. 1997, SEMARNAT 2000). We will discuss causes of this low survivorship and suggest some actions to improve the seedling survivorship and growth rate.
Governmental reforestations in México traditionally have relatively low success, with an officially estimated seedling survivorship of 34 % for the first year (Sheinbaum and Masera 2000, SEMARNAT 2000). It is reasonable to expect a much lower survivorship by later ages. There are several causes of the low seedling survivorship in México:
Some sites are too eroded already to support tree seedlings. There is an inappropriate tendency to plant pine seedlings independently of the level of degradation of the site (personal observation). This happen in part because is lacking methods and techniques of alternative ecological restoration strategies tested for Mexican conditions for different levels of site degradation (Lindig-Cisneros and Sáenz-Romero 2003)
In several cases there is an inadequate selection of species and provenances for appropriately matching adaptability potential of seedlings to ecological characteristics of plantation sites (Nienstaedt 1994). Reforestation program typically are conducted with an over-representation of pine species. For example, pine seedlings represent 74 % of seedlings planted in the western state of Michoacán, where only 30 % of the forest land is covered by pine or oak-pine forest (COFOM 2001). This is in part because there is not enough knowledge about how to propagate a large number of endemic plant species. Also, there are not enough available results of species and provenance field tests that would help to decide the appropriate species and provenances for specific sites.
Reforested sites in many cases are insufficiently protected against grazing, forest fires and competition by natural vegetation and exotic vegetation -like introduced grasses. This is because there is insufficient planning for preparing and protecting in advance the sites that will be reforested and there is insufficient budget to establish fences and provide post-planting maintenance. For example, in Michoacán state only 3 % of the federal and state reforestation program is allocated to maintenance of reforested sites (COFOM 2002). Such budgeting assumes that forest land owners should provide the maintenance for the reforested lots. However, poverty in the Mexican countryside is such that the vast majority of Mexican forest land owners are reluctant or it is simply economically impossible for them to provide unpaid labor for maintenance of the reforestations.
Frequently planting operations continue even when the rainy season is too advanced and seedlings will not have enough time for establishing before the dry season (Nienstaedt 1994, Sáenz-Romero and Martínez-Palacios 2000). This happen because there is not enough personal and field vehicles of the governmental agencies involved in the reforestation program for planting all the seedlings in the beginning of the rainy season.
Seedlings frequently have poor quality (Nienstaedt 1994, Sáenz-Romero and Martínez-Palacios 2000). For example, seedlings have too large aerial biomass regarding root biomass. This is frequently because the number of seedlings set as production goal exceeds by far the operational budget of forest nurseries.
Seedlings survivorship and growth rate in reforested sites need to be significantly improved in order to actually counteract the negative effects of deforestation in México. Two main actions are needed:
First, it is needed a substantial increase of the budget allocated per reforested hectare to the federal and state government reforestation program called National Reforestation Program (PRONARE by its acronym in Spanish). The current PRONARE's budget of approximately 58 million USD (CONAFOR 2002), which we estimated it means 276 USD per ha and 0.25 USD per planted seedling (considering that 3 m x 3 m is the standard spacing used in reforestations), is barely enough to produce poor quality seedlings and to plant them. Thus, either (a) Mexican government needs to increase substantially the budget allocated to the reforestation programs, perhaps at least four times of what it is programmed at present, or (b) Mexican government needs to decrease substantially the number of hectares reforested, perhaps from nearly 200,000 ha/year to 50,000 ha/year, which keeping the current budget will increase the quality and maintenance of the reforestations.
There are few communities very well organized with integrated forest industry which includes from sustainable management of natural stands (with successful natural or artificial regeneration) up to sales of well made furniture, like the Purepecha ethnic community of Nuevo San Juan Parangaricutiro, in Michoacán state (Sanchez-Pego 1995, Jaffee 1997). A community like that has the natural and financial resources, the training and the organization for taking care of the reforestations by their self. Unfortunately, their case is rather an exception, and heavier subsidies are needed to achieve a more successful reforestation in most of the country side.
Second, it is needed a substantial increase in financial support for research and management on the following issues:
Test different strategies to achieve ecological restoration depending of the level of degradation of the sites (Hobbs and Norton 1996). For example, to establish native grasses, then nitrogen fixing shrubs and then trees.
Generate technology to obtain propagation (at operational level) of endemic species like nitrogen fixing shrubs (e.g. Lupinus), nitrogen fixing trees and keystone species of the tropical dry forest, like tree species of the genus Bursera.
Test new ways to produce seedlings in forest nurseries, alternatively to the current practices of using plastic bag containers and forest soil.
Establishing a large number of field tests of species and provenances and delimiting seed zones, as guidelines for deciding seed and seedling transfers, in order to have reliable information for appropriately matching growth and adaptability potential of species and provenances to ecological conditions of sites that will be reforested. Delimitation of seed zones should be provisionally done based on climatic information, topography, species distribution and administrative boundaries, while provenance tests and common garden tests are developed and seed zone delimitation is confirmed (Nienstaedt et al. 1990, Saenz-Romero and Clausen 1991).
Within each seed zone, it would be desirable to have designated seed stands and establishing seed production areas and seed orchards -which will require previously tree selection and progeny tests.
Within each seed zone is needed to establish gene resource management units (GRMU) (Millar and Libby 1994), at least one for each pine species designated as priority for conservation and economical reasons (Sáenz-Romero 1990). A GRMU is a representative natural stand with the management priority of maintaining the genetic diversity (Ledig 1988, Millar and Libby 1991, Ledig 1992). This can be achieved by regeneration within a GRMU obtained either by natural recruitment or by reforestation using the local seed source (Ledig 1988), and by protecting the population from incoming foreign genetically alien pollen with a designated or planted tree belt. The GRMU will help to ensure diversity of the genetic resources in the future, particularly given the present alarming deforestation rate and considering the large biodiversity richness of México.
Mexican Federal government, by the National Forestry Commission (CONAFOR by its acronym in Spanish) has taken the right direction, opening recently a modest 5.4 USD million budget call for research proposals addressing forestry issues.
The large biodiversity of México and in particular the diversity of the genus Pinus represented in México, in the context of an accelerate rate of deforestation, make urgent to improve the success of the reforestation program currently sponsored by the government. It is needed either to increase substantially the current budget allocated to reforestation program or to decrease the number of seedlings produced and hectares reforested and to increase the seedling quality and maintenance of the reforested lots. It is needed also a large investment in research to develop new methods and techniques of ecological restoration, plant propagation and seedling production in nurseries, as well as developing seed zones and guidelines for seed and seedling transfer and to establish seed stands, seed production areas and seed orchards. It is needed to establish genetic resource management units, in order to conserve a representative sample of the genetic variation within species, before current forest fragmentation by deforestation make irreversible the looses of valuable forest genetic resources.
Funding was provided by the Mexican Council of Science and Technology (CONACYT) subsystem "SIMORELOS" (project 20000306021) and by the Coordinación de la Investigación Científica, Universidad Michoacana de San Nicolás de Hidalgo. I thank the input on ecological restoration by Roberto Lindig-Cisneros and valuable comments from Tom Ledig and Jesús Vargas-Hernández.
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1 Instituto de Investigaciones sobre los Recursos Naturales, Universidad Michoacana de San Nicolás de Hidalgo (INIRENA-UMSNH). Apdo. Postal 12, Administración La Colina, Morelia Michoacán 58141, México. firstname.lastname@example.org