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The need of designing a monitoring network in Sierra de Guerrero motivated this paper. The study of the effect of deforestation of the forest needs of monitoring in the diversity. A quantitative evaluation of diversity is measured by estimating an index. Commonly the monitoring of biodiversity is based on the periodical selection of samples for evaluating the diversity. We propose to use sample information for determining post strata. They must constitute homogeneous zones in the forest. A stochastic program is developed for determining the post strata to be used for sampling. The procedure seems to be a good alternative with respect to the use of a heuristic procedure. The results presented are based on the data obtained in a research developed at one of the most important forest diversity reservoirs of Mexico [ABSTRACT FROM AUTHOR]

Since 2007 many developing countries have laid groundwork for Reducing Emissions from Deforestation and forest Degradation and sustainable management and conservation of forests (REDD +) under the auspices of the United Nations Framework Convention on Climate Change (UNFCCC). REDD + is aimed at incentivizing forest conservation and management in developing countries through policy programmers and local projects, which should in theory enhance the participation of very diverse actors in forest policy and governance. Here we explore the early years of REDD + in Mexico focusing on the alleged "participatory" nature of the REDD + initiative. Based on interviews and field observations with those involved in drafting the REDD + national strategy and in the implementation of small-scale pilot project activities, we investigate the meaning of participation for REDD + actors, their aspirations in this regard, and how procedural justice issues are being considered in early policy implementation. We demonstrate that the process set in motion to draft the strategy did not sufficiently involve sub-national governance levels, thus reducing the legitimacy of REDD + efforts, particularly in rural communities. We suggest that rural local actors should be further involved in REDD + decision-making forums, be provided with more information for a good understanding of REDD + implementation (e.g., pilot projects), and most importantly, be given a real chance to implement REDD + activities grounded on their own institutions and land-use practices. [ABSTRACT FROM AUTHOR]

Background: Studies on the relationship between biodiversity and ecosystem productivity have suggested that species richness and functional diversity are the main drivers of ecosystem processes. Several patterns on this relationship have been found, including positive, unimodal, negative, and neutral trends, keeping the issue controversial. In this study, taxonomic diversity and functional diversity as drivers of above-ground biomass (AGB) were compared, and the mechanisms that influence biomass production were investigated by testing the complementarity and the mass-ratio hypotheses. Methods: Using data from 414 permanent sample plots, covering 23% of temperate forest in the Sierra Madre Oriental (México), we estimated the above-gound biomass (AGB), taxonomic and functional diversity indices, as well as community weighted mean values (CWM) for three functional traits (maximum height, leaf size and wood density) for trees ≥7.5 cm DBH, in managed and unmanaged stands. To compare taxonomic diversity differences between managed and unmanaged stands we carried out a rarefaction analysis. Furthermore, we evaluated the relationship between AGB and taxonomic and functional diversity metrics, as well as CWM traits throught spatial autoregressive models. Results: We found a hump-shaped relationship between AGB and species richness in managed and unmanaged forests. CMW of maximum height was the most important predictor of AGB in both stands, which suggested that the mechanism underlaying the AGB-diversity relationship is the dominance of some highly productive species, supporting the mass-ratio hypothesis. Above-ground biomass was significantly correlated with three of the five functional diversity metrics, CWM maximum height and species richness. Our results show the importance of taking into account spatial autocorrelation in the construction of predictive models to avoid spurious patterns in the AGB-diversity relationship. Conclusion: Species richness, maximum height, functional richness, functional dispersion and RaoQ indices relate with above-ground biomass production in temperate mixed-species and uneven-aged forests of northern Mexico. These forests show a hump-shaped AGB-species richness relationship. Functional diversity explains better AGB production than classical taxonomic diversity. Community weighted mean traits provide key information to explain stand biomass in these forests, where maximum tree height seems to be a more suitable trait for understanding the biomass accumulation process in these ecosystems. Although the impact of forest management on biodiversity is still debated, it has not changed the AGB-diversity relationships in the forests of the Sierra Madre Occidental, Mexico. [ABSTRACT FROM AUTHOR]

Ecosystem restoration is gaining momentum worldwide, but restoration projects frequently fall short of addressing the human dimension, notably through the involvement of local people. While social participation has been recognized to have a fundamental role in the success and sustainability of forest management projects, it is frequently not incorporated into restoration project planning. We gathered responses from a national assessment program regarding the status of terrestrial restoration projects in Mexico. We found that most of these projects were limited to the use of a local short-term work force in tree planting activities and were designed to alleviate short term local socioeconomic tensions, indicating that effective social participation is not well understood by managers. [ABSTRACT FROM AUTHOR]

Management of conservation conflicts is a challenge of growing relevance for the effectiveness of protected areas worldwide, particularly in the case of socially inclusive areas such as biosphere reserves. For a successful management of the protected area, is critical to consider the social use of natural resources carried out by local populations linked to reserves, especially in socio-ecological contexts facing potential conservation conflicts (i.e., conflicts that have not yet arisen). We addressed the importance of an early detection of potential conflicts through the study of artisanal charcoal production by Yucatec Mayan communities located in the zone of influence of a biosphere reserve in Northwest Yucatan Peninsula, Mexico. Through semi-structured interviews with charcoal producers and in-depth interviews with environmental authorities linked to the reserve, we discuss the advantages associated to early detection of potential conservation conflicts for biosphere reserves' management. [ABSTRACT FROM AUTHOR]

Many studies have considered community-based forestry enterprises to be the best option for development of rural Mexican communities with forests. While some of Mexico's rural communities with forests receive significant economic and social benefits from having a community forestry enterprise, the majority have not formed such enterprises. The purpose of this article is to identify and describe factors limiting the formation of community forestry enterprise in rural communities with temperate forests in the Southern Mixteca region of Oaxaca, Mexico. The study involved fieldwork, surveys applied to Community Board members, and maps developed from satellite images in order to calculate the forested surface area. It was found that the majority of Southern Mixteca communities lack the natural and social conditions necessary for developing community forestry enterprise; in this region, commercial forestry is limited due to insufficient precipitation, scarcity of land or timber species, community members' wariness of commercial timber extraction projects, ineffective local governance, lack of capital, and certain cultural beliefs. Only three of the 25 communities surveyed have a community forestry enterprise; however, several communities have developed other ways of profiting from their forests, including pine resin extraction, payment for environmental services (PES), sale of spring water, and ecotourism. We conclude that community forestry enterprise are not the only option for rural communities to generate income from their forests; in recent years a variety of forest-related economic opportunities have arisen which are less demanding of communities' physical and social resources. [ABSTRACT FROM AUTHOR]

Foliar nutrient resorption (FNR) is a key process in the dynamics of nutrients in a forest ecosystem. Along with other factors, FNR regulates the chemical composition of the forest floor and, consequently, the rates of organic matter decomposition and soil nutrient availability. The main objective of the present study was to examine the effect of FNR of two deciduous oak species ( Quercus castanea and Q. deserticola) in the litter and soil nutrient dynamics, in addition to analyze whether the interaction between two species was positive (synergistic) or negative (antagonistic) through the mixed litter from two species. For this purpose, the nutrient concentration of green leaves, litterfall, litter and soil was measured, as well as soil microbial activity. These measurements were taken in isolated stands with the presence of one of the oak species and stands with the two oak species mixed. Quercus deserticola, with lower FNR, produced litter with a higher N concentration, which apparently enhancing microbial activity in the forest floor litter and increased nutrient transformations and soil fertility. In contrast, Q. castanea has a higher FNR and produced litter with a lower nutrient concentration. The microbial soil community associated with Q. castanea must therefore invest more energy in metabolic processes at the expense of biomass growth. However, forest floor nutrient transformations were more intense and soil fertility increased in areas where both species intermix; in this case, the latter species received the rich-nutrient litterfall of Q. deserticola. These results suggest a strong footprint of species traits on microbial activities and soil nutrient transformations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Dwarf mistletoes are widely studied because of their significant impact on host populations; however, few studies have focused on sympatric species. The understanding of their coexistence is important because it can provide useful knowledge for future management plans. We investigated the incidence, severity, and aggregation patterns of Arceuthobium vaginatum and A. globosum coexisting in Central Mexico. We estimated the correlation between both species incidences ( N = 75 plots), the incidence-severity correlation ( N = 47 plots) for each species, and the effect of biotic (host and non-host species abundance) and abiotic (altitude and slope) factors on the mistletoe incidence. In addition, we compared the hierarchical aggregation among and within plots of the two mistletoe species with a χ test. There is a clear dominance of A. vaginatum in the area, and both species incidences are negatively correlated with each other ( r = − 0.54, P < 0.05) and host abundance ( r = − 0.26, P < 0.05). The remaining factors were non-significant. Both species have a linear relationship between incidence and severity, i.e., they show a uniform increase in severity with incidence, which could help diagnose the degree of tree infection from incidence measurements. The species are aggregated within plots, but only A. globosum shows an aggregation among plots ( χ = 82.25, P < 0.001); aggregation has not been shown previously for two sympatric dwarf mistletoe species. Our results can improve the scientific basis for forest management planning to control dwarf mistletoe and maintain biodiversity. [ABSTRACT FROM AUTHOR]

Dilemmas of natural resources governance have been a central concern for scholars, policy makers, and users. Major debates occur over the implications of property rights for common resources management. After the Mexican Revolution (1910-1917), land was distributed mainly as ejidos conceived as a hereditary but unalienable collective form of property. In 1992, a new Agrarian Law was decreed that allows individual ownership by removing various restrictions over the transfer of land. Scholars have examined the reform mainly focusing on land-tenure changes and environmental fragmentation. This study examines how the new ownership regime is affecting collective decision-making in ejidos located in a tropical dry forest (TDF) ecosystem. Information on decision-making processes before and after the 1992 reform was gathered through 52 interviews conducted in four ejidos selected along a gradient including agricultural, cattle-raising, and TDF use. The new individualized land property system reduced collective action in ejidos but did not trigger it. Collective action responses to the 1992 reform were buffered by self-organization each ejido already had. Heterogeneous users who shared a short history and showed little understanding of TDF and low dependence on its resources seemed to explain why ejidos have not been able to share a sense of community that would shape the construction of institutions for the collective management of forest resources. However, when a resource is scarce and highly valuable such as water the same users showed capacities for undertaking costly co-operative activities. [ABSTRACT FROM AUTHOR]

A common popular assertion is that trade liberalization encourages deforestation. But whether this is true depends on how trade policies affect the allocation of land among competing uses and how they influence illegal cutting of public forests. A model is presented that allows for forests to be either public or private, and public forests are divided into protected (or managed) and threatened categories. Effects of price changes are shown on each part of the forest. An empirical version of the model is applied to the case of Mexico with NAFTA. Most scenarios considered show that NAFTA will have positive long-runeffects on forest cover in Mexico but that this is net of losses on private lands. [ABSTRACT FROM AUTHOR]

Common property regimes may contribute to environmental conservation and offer a complementary institutional model to state-run protected areas. The potential conservation value of common property management is of particular significance in Mexico, where a large majority of forests are held communally. Systems of common property management often exist in a context of close institutional overlap with state institutions. This project assessed the function of a common property regime nested within Lagunas de Montebello National Park (PNLM) in Chiapas, Mexico. We documented forest status and analyzed common property forest management institutions following severe fires that threatened forest conservation. Forests managed by the common property regime are less intact than federal forests, yet still moderately conserved, and many attributes necessary for common property management are functional, despite the recent fire crisis. Yet external authorities contest common property management by local institutions, resulting in limited joint management by the national park and the community. Formalization and expansion of de facto cooperation between the federal and community institutions may enhance forest conservation within PNLM. [ABSTRACT FROM AUTHOR]