Phosphorus Biogeochemistry and the Impact of Phosphorus Enrichment: Why Is the Everglades so Unique?

The Florida Everglades is extremely oligotrophic and sensitive to small increases in phosphorus (P) concentrations. P enrichment is one of the dominant anthropogenic impacts on the ecosystem and is therefore a main focus of restoration efforts. In this review, we synthesize research on P biogeochemistry and the impact of P enrichment on ecosystem structure and function in the Florida Everglades. There are clear patterns of increased P concentrations and altered structure and processes along nutrient-enrichment gradients in the water, periphyton, soils, macrophytes, and consumers. Periphyton, an assemblage of algae, bacteria, and associated microfauna, is abundant and has a large influence on phosphorus cycling in the Everglades. The oligotrophic Everglades is P-starved, has lower P concentrations and higher nitrogen–phosphorus (N:P) ratios, and has oxidized to only slightly reduced soil profiles compared to other freshwater wetland ecosystems. Possible general causes and indications of P limitation in the Everglades and other wetlands include geology, hydrology, and dominance of oxidative microbial nutrient cycling. The Everglades may be unique with respect to P biogeochemistry because of the multiple causes of P limitation and the resulting high degree of limitation.

The multiple dimensions of political trust in democratic Argentina

Why do Argentines continue to support democracy despite distrusting political institutions and politicians? Support for democracy is high even though performance of the regime is poor. One would suspect that poor economic and political performance would open the door for military intervention given the history of Argentina. What changed? What explains variance across the multiple dimensions of political trust, such as trust in the regime, trust in political institutions, and trust in politicians? This dissertation is a case study of political culture through public opinion exploring the multiple dimensions of political trust in Argentina during the 1990s. ^ Variance across the different dimensions of political trust may be an indicator of the rise of a new type of citizens called "critical citizens." Critical citizens are citizens who criticize the regime to obtain democratic reforms but support the ideals of democracy. In established democracies, the rise of critical citizens is explained by a shift in individuals' value priorities towards postmaterialism. Postmaterialism is a cultural change in the direction of values that emphasize self-realization and individual well-being. Postmaterialism influences various social and political attitudes. ^ Because Argentina is experiencing a cultural change and a rise of critical citizens similar to more advanced societies, the theory of postmaterialism generated the main hypothesis to explain the multiple dimensions of political trust. This dissertation also tested an alternative explanation: the multiple dimensions of political trust responded instead to citizens' evaluations of performance. Ultimately, postmaterialism explained trust in the political regime and trust in the political institutions. Contrary to expectations, postmaterialism did not explain trust in the political elites or politicians. Trust in politicians was better explained by the alternative hypothesis, performance. ^ The main method of research was the statistical method supplemented with the comparative method when data were available. Two main databases were used: the World Values Surveys and the Latinobarometer. ^