Boundaries and Corridors as a Continuum of Ecological Flow Control: Lessons from Rivers and Streams

Abstract

Landscape boundaries and corridors are areas of small spatial extent relative to their large effects on ecological flows. The trend in ecological literature is to treat corridors and boundaries as separate phenomena on the landscape. This approach, however, misses a fundamental aspect they have in common: their strong influence on ecological flows. Corridors and boundaries exist at opposite ends of a permeability gradient, differing in their effects on rates and direction of flow. The position of landscape structures along this permeability gradient depends on attributes of both the flow and of the structure itself. We discuss boundaries and corridors in terms of mover specificity, scale, and effects on different levels of ecological organization, using rivers and streams to illustrate our points. We predict which structures will act as boundaries or corridors and at what spatial and temporal scales they are likely to be relevant. Considering the function of landscape structures across the boundary-corridor continuum will provide researchers and managers with a more complete, holistic viewpoint and will allow better strategies to attain conservation goals. Linderos y Corredores Como un Control de Flujo Ecológico Continuo: Lecciones de Ríos y ArroyosResumen: Los linderos y corredores de paisajes son áreas de extensión espacial pequeña con relación a la gran magnitud de sus efectos en los flujos ecológicos. En la literatura ecológica existe la tendencia de tratar a los corredores y a los linderos como un fenómeno separado en el paisaje. Sin embargo, esta estrategia pierde la característica común fundamental entre estos dos elementos: una fuerte influencia en los flujos ecológicos. Los corredores y los linderos existen a en extremos opuestos de un gradiente de permeabilidad, difieren en sus efectos en cuanto a las tasas y la dirección del flujo. La posición de estructuras del paisaje a lo largo de este gradiente de permeabilidad depende de los atributos tanto del flujo, como de la estructura en sí misma. Nosotros discutimos los linderos y los corredores en términos de especificidad del transportador, la escala y sus efectos en diferentes niveles de organización ecológica y utilizamos ríos y arroyos para ilustrar nuestros puntos. Predecimos cuales estructuras actuarían como linderos o corredores y a que escala espacial y temporal podrían ser relevantes. Considerando que la función de las estructuras del paisaje a lo largo de un continuo lindero-corredor proporcionará a los investigadores y manejadores un punto de vista mas completo e integral y dará cabida a mejores estrategias para alcanzar las metas de conservación.

Diversity of Odonata (Insecta) in lotic systems from Serra da Bodoquena, Mato Grosso do Sul State, Brazil

“…The pattern of species richness found in our study is probably due to the physical characteristics of the studied rivers and the degree of surrounding landscape heterogeneity. Within some of the factors cited as influencing Odonata species richness (see Vannote et al 1980;Minshall 1984;Townsend 1989;Ward 1992;Clenaghan et al 1998;Jonsen & Taylor 2000;Puth & Wilson 2001;Cortes et al 2002;Wiens 2002), certainly the amount and diversity of microhabitat within a given stretch of the river seem to be important. The immature stages of many species of Odonata inhabit various types of aquatic environments, but in most cases, exhibit preferences for specific types of habitats and substrates (Carvalho 1999), moreover, most adults exhibit territorial behavior, while remaining near the streams from which they emerged.…”

Fish ladder of Lajeado Dam: migrations on one-way routes?

“…In aquatic environments, dam construction limits the flow of nutrients, organisms, matter, energy and genetic information (Puth & Wilson, 2001), because of changes in the dynamics of the water and the effects of barriers. Among the biotic vectors capable of promoting these flows, migratory fishes are of great importance.…”

Mammals of Cabo Blanco: History, diversity, and conservation after 45 years of regrowth of a Costa Rican dry forest

“…There have been some warnings from conservation biologists about the potential negative effects of corridors, such as the spread of infectious diseases, invasive alien species, and an increase in predators along corridor pathways (Simberloff et al, 1992;Hilty and Merenlender, 2004;Weldon, 2006), but the balance of opinion currently favors the creation of corridors as a conservation and management tool. Furthermore, connectivity is increasingly a component of decisions about establishing reserves or developing an area for economic use (Puth and Wilson, 2001;Dzialak et al, 2005).…”