Gustavo Perez-Verdin

Patterns of Tree Species Diversity in Relation to Climatic Factors on the Sierra Madre Occidental, Mexico

Biological diversity can be defined as variability among living organisms from all sources, including terrestrial organisms, marine and other aquatic ecosystems, and the ecological complexes which they are part of. This includes diversity within species, between species, and of ecosystems. Numerous diversity indices combine richness and evenness in a single expression, and several climate-based explanations have been proposed to explain broad-scale diversity patterns. However, climate-based water-energy dynamics appears to be an essential factor that determines patterns of diversity. The Mexican Sierra Madre Occidental occupies an area of about 29 million hectares and is located between the Neotropical and Holarctic ecozones. It shelters a high diversity of flora, including 24 different species of Pinus (ca. 22% on the whole), 54 species of Quercus (ca. 9–14%), 7 species of Arbutus (ca. 50%) and many other trees species. The objectives of this study were to model how tree species diversity is related to climatic and geographic factors and stand density and to test the Metabolic Theory, Productivity-Diversity Hypothesis, Physiological Tolerance Hypothesis, Mid-Domain Effect, and the Water-Energy Dynamic Theory on the Sierra Madre Occidental, Durango. The results supported the Productivity-Diversity Hypothesis, Physiological Tolerance Hypothesis and Water-Energy Dynamic Theory, but not the Mid-Domain Effect or Metabolic Theory. The annual aridity index was the variable most closely related to the diversity indices analyzed. Contemporary climate was found to have moderate to strong effects on the minimum, median and maximum tree species diversity. Because water-energy dynamics provided a satisfactory explanation for the patterns of minimum, median and maximum diversity, an understanding of this factor is critical to future biodiversity research. Quantile regression of the data showed that the three diversity parameters of tree species are generally higher in cold, humid temperate climates than in dry, hot climates.

Key features for more successful place-based sustainability research on social-ecological systems: A Programme on Ecosystem Change and Society (PECS) perspective

The emerging discipline of sustainability science is focused explicitly on the dynamic interactions between nature and society and is committed to research that spans multiple scales and can support transitions toward greater sustainability. Because a growing body of place-based social-ecological sustainability research (PBSESR) has emerged in recent decades, there is a growing need to understand better how to maximize the effectiveness of this work. The Programme on Ecosystem Change and Society (PECS) provides a unique opportunity for synthesizing insights gained from this research community on key features that may contribute to the relative success of PBSESR. We surveyed the leaders of PECS-affiliated projects using a combination of open, closed, and semistructured questions to identify which features of a research project are perceived to contribute to successful research design and implementation. We assessed six types of research features: problem orientation, research team, and contextual, conceptual, methodological, and evaluative features. We examined the desirable and undesirable aspects of each feature, the enabling factors and obstacles associated with project implementation, and asked respondents to assess the performance of their own projects in relation to these features. Responses were obtained from 25 projects working in 42 social-ecological study cases within 25 countries. Factors that contribute to the overall success of PBSESR included: explicitly addressing integrated social-ecological systems; a focus on solution- and transformation-oriented research; adaptation of studies to their local context; trusted, long-term, and frequent engagement with stakeholders and partners; and an early definition of the purpose and scope of research. Factors that hindered the success of PBSESR included: the complexities inherent to social-ecological systems, the imposition of particular epistemologies and methods on the wider research group, the need for long periods of time to initiate and conduct this kind of research, and power asymmetries both within the research team and among stakeholders. In the self-assessment exercise, performance relating to team and context-related features was ranked higher than performance relating to methodological, evaluation, and problem orientation features. We discuss how these insights are relevant for balancing place-based and global perspectives in sustainability science, fostering more rapid progress toward inter- and transdisciplinary integration, redefining and measuring the success of PBSESR, and facing the challenges of academic and research funding institutions. These results highlight the valuable opportunity that the PECS community provides in helping build a community of practice for PBSESR.

Outdoor Recreation in a Protected Area in Southern Durango, Mexico: Analysis of Local Residents' Perceptions

This research evaluated perceptions of local residents from three communities in southern Durango, Mexico, toward planning outdoor recreation in the Michilía Biosphere Reserve (MBR). We used personal interviews to gather information about the barriers that keep people from participating in recreation activities and concerns about potential impacts of increasing recreation in the MBR. Sixty-five percent of the survey participants had never visited the MBR. Lack of knowledge, lack of time, and lack of money were the main reasons residents gave for not visiting MBR. Results also found significant differences among residents of the three communities in their perceptions of some of the potential impacts of outdoor recreation including higher risk of wildfires, loss of traditional values, overcrowding, and an increase in labor supply. The implications of these findings are relevant for developing strategies to involve residents in public forums concerned with outdoor recreation planning for the MBR.

Diversity-Productivity Relationship in the Northeastern Tamaulipan Thornscrub Forest of Mexico

This research examines the diversity-productivity relationship in a semiarid scrubland, initially under late successional conditions and subsequently under early successional conditions created by experimental clearing, to explore the roles that productivity and stochastic mortality play in species exclusion in this environment. A total of fifteen plots were studied by measuring environmental conditions and biomass components of shrubs and seedlings. These stands were distributed along a productivity gradient across five different landforms. A hypothesis about the stochastic self-thinning mortality model along the gradient was evaluated with the diversity-productivity-environment data. The diversity-productivity relationship was linear and reversed between the early and late succession stages. The hypothesis of stochastic mortality of species exclusion was rejected in the early stages of succession and partially accepted in the mature stage of succession. Species exclusion was negatively related to productivity gradients, suggesting that strong interspecific competition occurs in high productivity plots and that a larger number of species can survive in higher abiotic stress landscapes. Further research is needed to understand the temporal and spatial variations of the ecological interactions that shape this plant community.

Physical and Economic Aspects to Assessing Woody Biomass Availability for Bioenergy Production and Related Supply Constraints

Questions related to energy supply, security, environmental sustainability, and possible alternative sources are of a growing concern due to population growth and increased energy demand. The main goal of this Chapter is to present different aspects related to the availability and recovery of woody biomass as a feedstock for bioenergy production in the southern United States. To facilitate growth of an emerging bioenergy industry it is important to identify feedstocks that are appropriate for bioenergy production. Common feedstocks include logging residues, small-diameter trees, mill waste, and urban wood waste. In addition, there are many factors affecting the estimation of woody biomass feedstock available for processing. They include the intensity and frequency of thinning operations, woody biomass accessibility and recovery, soil nutrient compensation as well as availability and type of existing forest inventory data. Other potential constraints that can affect utilization of woody biomass feedstocks for bioenergy include logging and transportation costs, landowner willingness to produce and sell woody biomass, feedstock storage issues, and mill processing capacity.

Molinillos Private Forest Estate, Durango, Mexico

Abstract Molinillos is a private estate that includes forests, and is located in the Sierra Madre Occidental mountain range within the state of Durango in Mexico. The estate is owned by five families in which the main business is forestry and ecotourism. The current owners acquired the land in 1994 from different sellers and decided to consolidate the properties to operate as one contiguous estate. The latest and currently active forest plan considers two types of management: one for irregular (uneven-aged) forest areas with a focus on selective harvesting, and the other for areas with even-aged forests. Attempts are made to maintain a forest condition that satisfies many objectives, including high biodiversity, improved wildlife habitat, low operational costs, and superior net economic benefits. The need for this new multi-objective approach arose quite naturally from the existing diversity of species composition, forest structure, soil quality, and topography. Some challenges remain to be met by the current owners. These include seeking forestry certification, which may help to ensure ownership commitment to high-quality forest management standards. In addition, the owners intend to be a local leader in ecotourism, which requires improvement of existing infrastructure, including access roads and electricity supply to the ownership. Finally, the owners want to ensure resource sustainability through compliance with local and federal legislation as well as diversifying forest management through hunting and ecotourism opportunities, the marketing of timber and non-timber products and services, and federal programs associated with payments for environmental services.

Spatial heterogeneity of factors influencing forest fires size in northern Mexico

In Mexico, forest fires are strongly influenced by environmental, topographic, and anthropogenic factors. A government-based database covering the period 2000–2011 was used to analyze the spatial heterogeneity of the factors influencing forest fire size in the state of Durango, Mexico. Ordinary least squares and geographically weighted regression models were fit to identify the main factors as well as their spatial influence on fire size. Results indicate that fire size is greatly affected by distance to roads, distance to towns, precipitation, temperature, and a population gravity index. The geographically weighted model was better than the ordinary least squares model. The improvement of the former is due to the influence of factors that were found to be non-stationary. These results suggest that geographic location determines the influence of a factor on fire size. While the models can be greatly improved with additional information, the study suggests the need to adopt fire management policies to more efficiently reduce the effect of anthropogenic factors. These policies may include more training for landowners who use fire for clearing, closure of roads, application of thinning, prescribed burning, and fire breaks in perimeters adjacent to roads.