1. A longstanding goal of ecology and conservation biology is to understand the environmental and biological controls of forest succession. However, the patterns and mechanisms that guide successional trajectories, especially within tropical forests, remain unclear. 2. We collected leaf functional trait and abiotic data across a 110-year chronosequence within a tropical dry forest in Costa Rica. Focusing on six key leaf functional traits related to resource acquisition and competition, along with measures of forest stand structure, we propose a mechanistic framework to link species composition, community trait distributions and forest structure. We quantified the community-weighted trait distributions for specific leaf area, leaf dry matter concentration, leaf phosphorus concentration, leaf carbon to nitrogen ratio and leaf stable isotopic carbon and nitrogen. We assessed several prominent hypotheses for how these functional measures shift in response to changing environmental variables (soil water content, bulk density and pH) across the chronosequence. 3. Increasingly, older forests differed significantly from younger forests in species composition, above-ground biomass and shifted trait distributions. Early stages of succession were uniformly characterized by lower values of community-weighted mean specific leaf area, leaf stable nitrogen isotope and leaf phosphorus concentration. Leaf dry matter concentration and leaf carbon to nitrogen ratio were lower during earlier stages of succession, and each trait reached an optimum during intermediate stages of succession. The leaf carbon isotope ratio was the only trait to decrease linearly with increasing stand age indicating reduced water use efficiency in older forests. However, in contrast with expectations, community-weighted trait variances did not generally change through succession, and when compared to null expectations were lower than expected. 4. The observed directional shift in community-weighted mean trait values is consistent with the 'productivity filtering' hypothesis where a directional shift in water and light availability shifts physiological strategies from 'slow' to 'fast'. In contrast with expectations arising from niche based ecology, none of the community trait distributions were over-dispersed. Instead, patterns of trait dispersion are consistent with the abiotic filtering and/or competitive hierarchy hypotheses.

The goal of this dissertation is to advance the theory of common-pool resources in three different but interrelated ways: (1) Common-pool resources theory has identified a number of factors that play an important role on human groups' ability to engage in successful institutional change. However it is still not clear which are their causal relationships on specific contexts. This study looks at the relationship between two of the aforementioned factors: local leadership and local autonomy. It does so in the context of the decentralization of the governance of protected areas for biodiversity conservation in Costa Rica. (2) Historically, common-pool resources theory has paid limited attention to the interactions between local institutions and higher levels of governance. This study incorporates the analysis of cross-scale institutional linkages into the assessment of decentralization reforms in Costa Rica. (3) To do so it incorporates an analytical approach that allows for systematic and rigorous comparisons of small-to-moderate-sized Ns and is apt at handling multiple-causality outcomes. Looking at these issues in the context of the decentralization of biodiversity governance in Costa Rica is relevant because it is the most biodiverse country per unit of area in the world, and during the last twenty years has experimented with decentralization policies to create locally-based institutions for biodiversity conservation. Among my most relevant findings are: (1) that the presence of local leadership is positively related to institutions ability to gain local autonomy from the central government. (2) However, in the context of a class-based society with a strong urban-rural divide, the emergence of local leadership for conservation in rural settings is likely not able to take place by itself without support from within the bureaucratic structure. (3) More diverse are better than less diverse sets of cross-scale linkages in local institutions' ability to gain and maintain local autonomy overtime. (4) Local autonomy can help local institutions increase their potential for biodiversity conservation as long as there are well-defined institutional arrangements in place. Otherwise, local institutions might find themselves pursuing other agendas that might have an unclear relation with biodiversity conservation.