Leopoldo Galicia

The relationship between solar radiation interception and soil water content in a tropical deciduous forest in Mexico

Abstract Spatial and temporal patterns of potential solar radiation interception (SRI) were estimated in a tropical deciduous forest ecosystem in the West of Mexico using a Geographic Information System modeling approach. The study area was a small catchment (16 ha) divided into three altitudinal segments: top, middle and bottom. Both amount and pattern of SRI were strongly influenced by aspect. It increased with slope inclination. Catchment relief affected SRI distribution throughout the year: the highest values were on the gently sloping top segments and south-facing bottom locations, and the lowest values were in the steep north-facing bottom locations. With the onset of the rainy season soil water content (SWC) was affected by soil characteristics, but SRI was still more important than these during the rainy season. Consequently, north-facing bottom locations had less SRI but greater SWCs for longer periods. In contrast, the top and middle locations with high SRI had smaller SWCs. Vegetation structure was also affected by SWC: the north-facing bottom locations had greater tree density and, greater tree diameter at breast height and greater leaf area than the top and middle levels.

Pattern of Rainfall Distribution in the Central Pacific Coast of Mexico

ABSTRACTThe Central Pacific coast of Mexico can be classified into four zones, each showing different rainfall patterns. As a result of tropical cyclone influence in the Pacific coast, the level of rainfall probability differs between zones. Such influence is revealed in the total annual rainfall, in the seasonality and in the monthly rainfall pattern.

Evaluating drivers of land-use change and transition potential models in a complex landscape in Southern Mexico

Understanding and analysis of drivers of land-use and -cover change (LUCC) is a requisite to reduce and manage impacts and consequences of LUCC. The aim of the present study is to analyze drivers of LUCC in Southern Mexico and to see how these are used by different conceptual and methodological approaches for generating transition potential maps and how this influences the effectiveness to produce reliable LUCC models. Spatial factors were tested for their relation to main LUCC processes, and their importance as drivers for the periods 1993–2002 and 2002–2007 was evaluated by hierarchical partitioning analysis and logistic regression models. Tested variables included environmental and biophysical variables, location measures of infrastructure and of existing land use, fragmentation, and demographic and social variables. The most important factors show a marked persistence over time: deforestation is mainly driven by the distance of existing land uses; degradation and regeneration by the distance of existing disturbed forests. Nevertheless, the overall number of important factors decreases slightly for the second period. These drivers were used to produce transition potential maps calibrated with the 1993–2002 data by two different approaches: (1) weights of evidence (WoE) to represent the probabilities of dominant change processes, namely deforestation, forest degradation, and forest regeneration for temperate and tropical forests and (2) logistic RM that show the suitability regarding the different land-use and -cover (LUC) classes. Validation of the transition potential maps with the 2002–2007 data indicates a low precision with large differences between LUCC processes and methods. Areas of change evaluated by difference in potential showed that WoE produce transition potential maps that are more accurate for predicting LUCC than those produced with RM. Relative operating characteristic (ROC) statistics show that transition potential models based on RM do usually better predict areas of no change, but the difference is rather small. The poor performance of maps based on RM could be attributed to their too general representation of suitability for certain LUC classes when the goal is modeling complex LUCC and the LUC classes participate in several transitions. The application of a multimodel approach enables to better understand the relations of drivers to LUCC and the evaluation of model calibration based on spatial explanatory factors. This improved understanding of the capacity of LUCC models to produce accurate predictions is important for making better informed policy assessments and management recommendations to reduce deforestation.

Land Use and Land Cover Change in Highland Temperate Forests in the Izta-Popo National Park, Central Mexico

Abstract The long-term preservation of national park ecosystems requires scientific knowledge about land use/cover change (LUCC) that influences these ecosystems. LUCC in Mexican temperate mountain forests as depicted in satellite imagery was evaluated for 3 time intervals: 1970–1980, 1981–1990, and 1991–2000. Forest cover declined at an average rate of 0.35 ha per year due to timber extraction, cultivation, grazing (areas grazed by cattle), and urbanization processes. Historically, cultivation has resulted in such a high loss of plant communities in lowlands that regional diversity has been threatened. Currently, though, cultivation has been reduced due to a decline in the economic importance of corn and bean crops. By contrast, grazing has increased due to low labor costs and economic policies that provide incentives for cattle production in Mexico. The abandonment of cultivated land due to economic processes may have strong implications on the regeneration of plant communities in temperate forests. Highland temperate forest and subalpine grasslands remain relatively intact due to national park protection, which is essential to maintain species diversity at a regional scale.

Soil carbon dynamics in high-elevation temperate forests of Oaxaca (Mexico): thinning and rainfall effects

Resumen en: To explore the forest harvest effects on biologically active fractions of soil organic matter dynamics, we evaluated soil total carbon (C-total) and soil...

Multiple ecosystem services, possible trade-offs and synergies in a temperate forest ecosystem in Mexico: a review

Identification of the ecosystem services provided by Mexican temperate forests is a prerequisite in ensuring their conservation and sustainable management. This study aimed (1) to describe ecosystem services provided by Mexican temperate forests (provisioning, regulating and cultural services); and (2) to identify possible trade-offs and synergies based on the types of ecosystem services available in Mexican temperate forests. We synthesized relevant literature from scientific articles, government statistics and grey literature covering the years 1985–2012. Timber extraction is the main beneficial ecosystem service of temperate forests recognized by public policy as shown by the high income from this activity; but it has trade-offs of greater magnitude with other provisioning services (water, bioenergy and non-timber forest resources), and with other supporting, regulating and cultural ecosystem services. For example, it causes the loss of other forest resources, extinction of commercially important species and loss of the systems structural complexity. Water capture and extraction of non-timber forest resources have lesser effects on support and regulation services, and in the case of water capture, the magnitude of the effect depends on the type and reversibility of the modification of the ecosystem. The synergies between ecosystem services have mutual benefits; for example, a decision to enhance the scenic beauty in temperate forests potentially improves water cycling and provision of non-timber forest resources, and has a positive effect on cultural and regulation services. In Mexican temperate forests the recognition of ecosystem services is limited and is based largely on grey literature. More robust scientific information is needed on the role of these forests in maintaining biodiversity and provision of ecosystem services essential to the welfare of the population. Also, monitoring of ecosystem processes of highland temperate forests in tropical regions is very limited, so it is necessary to generate research to develop a paradigm shift from forest management based strictly on logging to one based on ecosystem management.

Climate change impacts and adaptation strategies in temperate forests in Central Mexico: a participatory approach

Worldwide temperate forests are vulnerable to climate change because climate anomalies may impact tree mortality and forest productivity, as well as the economic and social dynamics of the people that depend on forest services. Evaluation of their vulnerability is a key element for the impact scenarios under climate change and for the design of adaptation strategies. The objective of this study is to analyze the case of forests in central Mexico and the importance of land degradation as a factor that increases vulnerability to warmer than normal temperatures that may result in forest fires. By means of data analyses and participative workshops, current vulnerability factors of temperate forests ecosystem to a warmer climate have been identified and found to be related to local traditional practices, like slash and burn, illegal extraction, deforestation and land use change that have led to loss of biodiversity and ecosystem services. However, various stakeholders now admit that some of their practices on the use of forest resources lead to vulnerability to climate anomalies. If current trends in vulnerability continue, and climate change makes drier conditions more frequent, forest extension in the Central Mexico could be severely reduced mainly by wildfires, pests and loss of ecological services. In a number of workshops, stakeholders’ from the forests of Tlaxcala suggested three adaptation measures: i) forest conservation, ii) forest restoration and iii) sustainable forest management. Particular adaptation strategies are considered more appropriate for some communities that expect long term benefits (augmenting water resources, soil erosion mitigation and flood control). Therefore, it is concluded that perception and ancestral knowledge of stakeholders need to be incorporated in the vulnerability analysis in order to have them involved in the adaptation process and to empower them in the implementation of the adaptation strategies.

Scenarios and story lines: drivers of land use change in southern Mexico

The study presents three scenarios of land use and cover change (LUCC), the most important factor for environmental degradation in southern Mexico. We developed story lines and quantitative projections for regional scenarios based on historic LUCC processes, environmental policies, socioeconomic drivers, stakeholder consultations and official planning documents to gain a better understanding of drivers of LUCC, and quantitative scenarios were modeled with DINAMICA-EGO. Regionally specific interactions between social and natural systems are recognized, and detrimental policies and policy options for landscape conservation and management for sustainability are acknowledged in a base line, variant and alternative scenario. Incongruent policies and ineffective ground implementation of conservation actions were identified as the critical underlying drivers of deforestation and forest degradation that could lead to a severe reduction in natural forests, while the local socioeconomic situation stays precarious. The baseline scenario parts from an analysis of historic LUCC processes and shows the consequences of LUCC tendencies: 73% of temperate forests and 50% of tropical forests would get deforested until 2030. In the variant scenario, these tendencies are adjusted to planning goals extracted from official documents and recent changes in public policies. The alternative scenario further addresses policy options for fostering conservation and sustainable development, but because of the time lag of implementation, still 59% of temperate forests and 36% of tropical forest would get lost until 2030. Nevertheless, this represents a reduction of 13% of forest loss and 11% less pastureland due to the proposed measures of conservation, and sustainable management, including strategies for reforming agricultural systems, agricultural and forestry policies and trade, land tenure and livelihood risk management.

Litter Quality of Two Remnant Tree Species Affects Soil Microbial Activity in Tropical Seasonal Pastures in Western Mexico

In degraded soils of tropical seasonal pastures, native remnant tree species that differ in foliar morphology, litter quality, and quantity might be quite useful as an organic input for improving soil fertility. The objective of this study was to analyze litter quality effects on soil microbial activity from two native remnant trees: Caesalpinia eriostachys Benth. (Caesalnaceae) and Cordia elaeagnoides DC (Boraginaceae), located within a tropical seasonal pasture matrix dominated by Panicum maximum Jacq. (Poaceae). The substrate-induced respiration method was used to determine soil microbial activity in a laboratory incubation experiment. A 3 × 3 factorial laboratory experiment for litter type and soil origin was carried out by adding leaf litter to soil in a reciprocal fashion to evaluate the relative effect of litter quality on substrate-induced respiration. Potential C mineralization rate and net microbial C immobilization from soil under C. elaeagnoides and C. eriostachys were higher with endogenous litter (260 ± 24 µg C g−1 d−1 and 242 ± 11 µg C g−1 d−1 for C. elaeagnoides and C. eriostachys, respectively) than with exogenous litter. Potential carbon mineralization and net microbial C immobilization in soil under P. maximum increased with litter from C. eriostachys due to other leaf-litter quality parameters as lignin concentration and lignin:N ratio. Therefore, C. eriostachys litter addition on soil under grass species may help to stabilize soil organic matter, promoting soil microbial biomass and activity. The net immobilization of microbial N under two remnant tree species and grass species was negative, indicating an N mineralization from microbial biomass.

Metal distribution in coral reef complex Cayo Arcas in the Gulf of Mexico

This study evaluated the spatial and temporal distribution of metals in the coral reef system Cayos Arcas and Triangulos in the Campeche Bank region, off the Yucatan peninsula in Mexico. No information has been generated before for the incorporation of natural and non-natural occurring metals, some of which are possibly endowed by the oil marine station Cayo Arcas. The multivariate exploratory study of the metals on the coral skeletons, showed the formation of two distinct groups. The metals that have the highest influence on the differentiation of the groups are the metals that are natural constituents of the coral skeletons, in particular Sr can explain much of the differences between the groups, and to a much lesser extent are the metals that could be indicators of pollution. This differentiation suggests that, in our case, the environment around the corals has a higher impact than the non-naturally occurring metals (and possible indicators of pollution). The two groups formed corresponded to: the coral cores influenced by open sea variables and the coral cores in the inner part of the keys which is less exposed to open sea variables. A chronological study was made to two samples that had the longest coral section and were situated in two clearly distinctive zones: an exposed surface subjected to high wave forces and another that was less exposed. Ni and Zn show an accumulation trend in both coral samples, while Ba showed an increase in incorporation around 1980 when the Cayo Arcas oil marine station was constructed.