Julia Carabias

Environmental deterioration in rural Mexico: an examination of the concept

Mexico, like many other countries worldwide, faces an environmental crisis of enormous proportions. While in its urban dimension environmental problems are more similar to those of developed countries, in rural areas they are analogous to those prevailing in developing countries. In rural areas, which are largely devoted to food production based on traditional methods, environmental concerns are mainly related to phenomena such as deforestation and soil erosion, and not to chemical pollution or ozone-layer depletion, which are the primary concerns of the broad public. The future food production in these regions and the possibility of improving the life quality of their inhabitants depend on our understanding of these kinds of problems, and our capacity to confront them. An overview of the theoretical framework on environmental deterioration reveals a lack of definition of the concepts and terms related to this issue. Several terms, such as “desertification” and “fragmentation,” among others, are widely used by ecologists but are clearly not synonymous with environmental deterioration. A consequence of this vagueness is the lack of clear criteria to differentiate areas that are only moderately modified from those in which true deterioration has occurred. Also, unified methods to efficiently evaluate environmental deterioration in rural areas are lacking. We briefly present a case study in which environmental deterioration was evaluated in La Montana, an extremely poor and climatically and topographically heterogeneous rural region inhabited by indigenous people in southern Mexico. Three deterioration categories are recognized based on degree of human influence, proportion of vegetation cover, and soil erosion severity. Use of air photogrammetry supplemented with field surveys revealed that 13% of La Montana is already damaged (i.e., lacking native vegetation and affected, perhaps irreversibly, by severe erosion), while 36% is altered (i.e., where native vegetation is substantially modified, but productive activities are still possible). In turn, almost three quarters of the land in the latter category is at high risk of becoming damaged. An analysis of the patterns of land-use changes around selected villages for the period 1979–1992 showed local annual deforestation rates ranging between 1 and 17%, depending upon climatic conditions. Based on the conceptual review and the analysis of the case study, we suggest that environmental deterioration comprises at least three clearly distinct dimensions: the abiotic setting, the biological attributes, and the social characteristics of the process. Finally, we define environmental deterioration as any modification of the environment that implies a reduction or loss of its physical and biological qualities, caused by natural phenomena or human activities, ultimately representing a decrease in the availability of ecosystem goods and services to human populations. The methods used to evaluate environmental deterioration at La Montana allowed us to separate modifications that cause deterioration from those that do not. This investigation, carried out in a relatively short time and with a minimum financial investment, yielded a satisfactory assessment of the state of the environment at the regional and community scales, recognizing early indicators of deterioration. This approach may be particularly useful in rural regions that share many characteristics with La Montana, such as critical environmental problems, extreme poverty, and insufficient background information about these issues.

Growth analysis of nine multipurpose woody legumes native from southern Mexico

The growth of nine multipurpose woody legumes was evaluated in nursery conditions. These species, belonging to the genera Acacia, Leucaena, Lysiloma, Prosopis and Pithecellobium, inhabit both primary and secondary tropical deciduous and thorn forests. The total length of the experiments was 165 days. At a variable frequency, the following four variables were measured: (1) relative growth rate (RGR), (2) root/shoot ratio (R/S), (3) root length/root dry weight ratio (RL/RDW), and (4) stem length (SL). The temporal behavior of these variables differed greatly among species. A direct relationship between seed weight and initial biomass production was initially found; however, the effect of seed size on biomass production was lost as plants aged. At the initial harvest, RGR values did not differ significantly among species, but they did at the end of the experiment; Pithecellobium dulce had the lowest final RGR. The three Acacia species had the highest biomass productions and highest R/S ratios but the lowest RL/RDW ratios; A. farnesiana and Lysiloma divaricata had the largest mean SL, whereas the smallest mean SL corresponded to the two Leucaena species and to Lysiloma acapulcensis. Several recommendations concerning the management of plants in the nursery and the optimal timing for transplanting the seedlings to reforestation sites are provided.

Seed germination of woody legumes from deciduous tropical forest of southern Mexico

Abstract Seed germination experiments were conducted on six woody leguminous species which are widely used by rural inhabitants of a mountainous tropical subhumid region in southern Mexico. Conditions for optimum germination were sought in nursery conditions by applying various hot water treatments (1 min, 3 min, 5 min and 10 min in boiling water) and scarification to seeds of differing storage durations. Lysiloma divaricata germinated promptly without any treatment. Leucaena esculenta and L. macrophylla seeds germinated more readily after boiling (1 min), regardless of storage duration. Acacia species (A. cochliacantha, A. farnesiana and A. pennatula) had optimum germination with scarification treatments for all storage durations, while short-time boiling (1 min, 3 min) of their seeds increased germination only moderately. Seeds of species typical of primary vegetation lost viability sooner than those of species more frequent in disturbed areas. From these results, seed handling routines and germination pre-treatments practices can be derived for these species, all of which can potentially be used in reforestation on degraded soils.

Social Perceptions of Rainforest and Climatic Change from Rural Communities in Southern Mexico

Understanding social perceptions of rural communities is essential to construct public policy and management alternatives, not only to maintain natural ecosystems but also to deal with a changing environment due to climatic change. Because climate variability in Mexico has important socio-economic and environmental impacts, it is necessary to build capacities for adaptation. We describe social perceptions of three main local stakeholders (that is, farmers, elders, and local authorities), regarding their relationships with rainforest and local adaptation to climate change in eleven rural communities in Marqués de Comillas municipality, Chiapas, Southern Mexico. We based in a qualitative approach and used participant observation and semi-structured interviews. Even certain subtly variation among stakeholders, we recognized some underlying ideas behind perceptions. Rainforest is considered crucial to maintain human livelihoods and to mitigate climatic changes. They perceived changes in climate occurring in the region, such as raising temperature, unpredictable rainfall, and streams becoming dry. Local organization and government involved in managing rainforest or dealing with climatic changes are practically absent. This emphasizes the needs bring proper and reliable information to make decisions regarding rainforest use and management, but also to adapt to a changing climate. The loss of the collective character of the communities and, certain conflicts in public policies that mirrored in the coexistence of initiatives with contrasting objectives are proposed as particularly important for understanding the emergence of these perceptions. We proposed some recommendations to bolster regional capacities addressing climate change. Involving stakeholders such as governmental and non-governmental institutions is also imperative.