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La orientación general de este trabajo concierne la explotación óptima de recursos naturales renovables con un interés particular en las plantaciones forestales compuestas por múltiples especies.

Sustainable forest management (SFM) considers the social and ecological aspects of forestry apart from the productive ones. However, the relative importance of its principles changes in each type of forest. Criteria and indicators (C&I) extend the knowledge and understanding of SFM in each different situation. A set of C&I to be applied under Mediterranean conditions is proposed in this thesis. The scope was set for the forest management unit (FMU). The C&I proposed took into account the Spanish context and the Forestry Regional Plan for the region of Valencia (whose Spanish acronym is PATFOR) served as a reference. The thesis is made of three papers, two of them published and one accepted. The first identified the requirements of SFM under Mediterranean conditions and analysed the Spanish situation. For that purpose, a strengths-weaknesses-opportunities-threats (SWOT) analysis was carried out and strategies for improvement were determined. The results of the SWOT analysis together with the strategies and the requirements identified by means of literature review were verified in a questionnaire sent to experts. In the second paper, a group of criteria recommended to take into account for the success of a participatory process were established. A review of case studies which had developed decision support systems (DSSs) including elements of participation was completed. Conslusions were considered for the method applied in the third paper and they helped to identify indicators for the criterion “participatory processes”, which is one of the criteria proposed in this thesis. Besides, PATFOR recommends including participation in forestry decision-making. The third paper started adaptating various ecosystem services frameworks to Mediterranean conditions. PATFOR suggests that forestry is more sustainable if it stems from the provision of ecosystem services, even more in Mediterranean forests because they are not very productive in general. Management criteria which maintain and improve the provision of ecosystem services were identified. A participatory process took place in Ayora (a village in the region of Valencia); participants were asked to rank the criteria identified according their management preferences for La Hunde y La Palomera, a FMU near the village. A proposal of indicators was another output of this paper. The thesis includes another chapter which does not correspond to any published paper; it describes the elaboration of a questionnaire that was sent to experts. The questionnaire asked respondents to prioritise the indicators proposed in the third paper following the Analytic Hierarchy Process (AHP) methodology. The result is a proposal of 15 criteria and 90 indicators. Criteria were inspired by the requirements of the first paper and the ecosystem services. 7 out of 15 criteria are social, noticeably increasing the weight of the social pillar in comparison with other existing C&I sets. Nevertheless, participants ranked ecological implications of forestry as the most preferred ones. However, they did not reject any of the criteria and this suggests that considering ecosystem services in forest management is realistic and desirable. Although the AHP questionnaire sent to experts was different from the participatory process, both in appearance and content, some comparisons can be made. Experts search for feasibility in their answers. It may be recommended from these differences that forestry decision-making takes into account the views of affected people, but their preferences might pass an expert filter before carrying out actions. Regarding the indicators, some more work on them is still necessary, but they show a simple writing and they refer to a specific aspect of each criterion. / Valls Donderis, P. (2015). Sustainable and participatory forestry under Mediterranean conditions: criteria and indicators for monitoring in a forest management unit of Comunidad Valenciana (Spain) [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48540 / TESIS

This study was conducted in burned and harvested areas of Catalonia. It was evaluated the effect of the granivorous in predispersive fruit removal of Smilax aspera and Quercus coccifera and postdispersive seed removal. Nuts removal by rodents was nil in the burned area while for S. aspera only occurred in 2008. The minimum distance to any unburned margin and the distance to the fire perimeter explained patterns of seed removal for rodents and ants, respectively. Seed removal was also lower at unlogged sites vs. logged ones but it was only significative for ants. Rodents removed more seeds under piles of branches because logging while ants did so in areas of bare soil. It should consider the impact of granivorous in the management of burned habitats. / Este estudio fue desarrollado en áreas quemadas y taladas de Cataluña. Se evaluó el efecto de los granívoros en la remoción predispersiva de frutos de Smilax aspera y Quercus coccifera así como la remoción postdispersiva de semillas. La remoción de Quercus por parte de roedores fue nula en el área quemada mientras que para S. aspera solo ocurrió en el 2008. La distancia minima a cualquier margen no quemado y la distancia al perímetro del incendio explicaron los patrones de remoción de semillas para roedores y hormigas, respectivamente. La remoción de semillas también fue menor en las estaciones taladas vs. las no taladas, pero solo de forma significativa para hormigas. Los roedores removieron más semillas bajo amontonamientos de ramas producto de la gestión forestal mientras que las hormigas lo hicieron en áreas de suelo desnudo. Se debería contemplar el efecto de los granívoros en la gestión de los hábitats quemados.

Dynamic optimization methods have become increasingly important over the last years in economics. Within the dynamic optimization techniques employed, optimal control has emerged as the most powerful tool for the theoretical economic analysis. However, there is the need to advance further and take account that many dynamic economic processes are, in addition, dependent on some other parameter different than time. One can think of relaxing the assumption of a representative (homogeneous) agent in macro- and micro-economic applications allowing for heterogeneity among the agents. For instance, the optimal adaptation and diffusion of a new technology over time, may depend on the age of the person that adopted the new technology. Therefore, the economic models must take account of heterogeneity conditions within the dynamic framework.This thesis intends to accomplish two goals. The first goal is to analyze and revise existing environmental policies that focus on defining the optimal management of natural resources over time, by taking account of the heterogeneity of environmental conditions. Thus, the thesis makes a policy orientated contribution in the field of environmental policy by defining the necessary changes to transform an environmental policy based on the assumption of homogeneity into an environmental policy which takes account of heterogeneity. As a result the newly defined environmental policy will be more efficient and likely also politically more acceptable since it is tailored more specifically to the heterogeneous environmental conditions. Additionally to its policy orientated contribution, this thesis aims making a methodological contribution by applying a new optimization technique for solving problems where the control variables depend on two or more arguments --- the so-called two-stage solution approach ---, and by applying a numerical method --- the Escalator Boxcar Train Method --- for solving distributed optimal control problems, i.e., problems where the state variables, in addition to the control variables, depend on two or more arguments.Chapter 2 presents a theoretical framework to determine optimal resource allocation over time for the production of a good by heterogeneous producers, who generate a stock externalit and derives government policies to modify the behavior of competitive producers in order to achieve optimality. Chapter 3 illustrates the method in a more specific context, and integrates the aspects of quality and time, presenting a theoretical model that allows to determine the socially optimal outcome over time and space for the problem of waterlogging in irrigated agricultural production. Chapter 4 of this thesis concentrates on forestry resources and analyses the optimal selective-logging regime of a size-distributed forest.