2003
Levine, Jonathan M.
A patch modeling approach to the community-level consequences of directional dispersal Journal Article
In: Ecology, vol. 84, no. 5, pp. 1215-1224, 2003.
Abstract | Links | BibTeX | Tags: coexistence, community, directional dispersal, disturbance, patch model, river, species diversity
@article{Levine2003b,
title = {A patch modeling approach to the community-level consequences of directional dispersal},
author = {Jonathan M. Levine},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/A-PATCH-MODELING-APPROACH-TO-THE-COMMUNITY-LEVEL-CONSEQUENCES-OF-DIRECTIONAL-DISPERSAL_Levine_2003.pdf},
doi = {http://dx.doi.org/10.1890/0012-9658(2003)084[1215:APMATT]2.0.CO;2},
year = {2003},
date = {2003-05-00},
journal = {Ecology},
volume = {84},
number = {5},
pages = {1215-1224},
abstract = {Although plants and other sessile organisms often disperse in a prevailing direction, the ecological consequences of this are poorly understood. To explore patterns of plant diversity similar to those found in a California river system, I modeled perennial plant populations and communities occurring in a linear series of neighborhoods connected by dispersal, where dispersal occurs in a prevailing downstream direction. Simulations demonstrated that population size and species diversity correlated with dispersal and increased downstream, but only if fecundity and death rates were such that neighborhoods within the system depended on external propagule input for their persistence. Highly effective downstream dispersal and some upstream dispersal were also required. If these demographic and dispersal criteria were met, communities with intense competition and inhibition still developed downstream increases in diversity. Additionally, in such systems, directional dispersal could favor species coexistence since upstream neighborhoods provided a refuge for inferior competitors. The demographic and dispersal criteria were relaxed for systems recovering from scattered source populations following disturbance. I conclude that directional dispersal may be a key determinant of species coexistence and patterns of diversity in severely propagule-limited systems.},
keywords = {coexistence, community, directional dispersal, disturbance, patch model, river, species diversity},
pubstate = {published},
tppubtype = {article}
}
Although plants and other sessile organisms often disperse in a prevailing direction, the ecological consequences of this are poorly understood. To explore patterns of plant diversity similar to those found in a California river system, I modeled perennial plant populations and communities occurring in a linear series of neighborhoods connected by dispersal, where dispersal occurs in a prevailing downstream direction. Simulations demonstrated that population size and species diversity correlated with dispersal and increased downstream, but only if fecundity and death rates were such that neighborhoods within the system depended on external propagule input for their persistence. Highly effective downstream dispersal and some upstream dispersal were also required. If these demographic and dispersal criteria were met, communities with intense competition and inhibition still developed downstream increases in diversity. Additionally, in such systems, directional dispersal could favor species coexistence since upstream neighborhoods provided a refuge for inferior competitors. The demographic and dispersal criteria were relaxed for systems recovering from scattered source populations following disturbance. I conclude that directional dispersal may be a key determinant of species coexistence and patterns of diversity in severely propagule-limited systems.
1996
Kupferberg, Sarah J.
Hydrologic and geomorphic factors affecting conservation of a river-breeding frog (Rana boylii) Journal Article
In: Ecological Applications, vol. 6, no. 4, pp. 1332-1344, 1996.
Abstract | Links | BibTeX | Tags: amphibians, Anura, frogs, geomorphology, hydrology, oviposition, physical habitat, Rana boylii, reproductive success, river, spatial scale
@article{Kupferberg1996,
title = {Hydrologic and geomorphic factors affecting conservation of a river-breeding frog (Rana boylii)},
author = {Sarah J. Kupferberg},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Kupferberg_EcolApp1996.pdf},
doi = {http://dx.doi.org/10.2307/2269611},
year = {1996},
date = {1996-11-00},
journal = {Ecological Applications},
volume = {6},
number = {4},
pages = {1332-1344},
abstract = {Organisms that live in highly variable environments, such as rivers, rely on adaptations to withstand and recover from disturbance. These adaptations include behavioral traits, such as habitat preference and plasticity of reproductive timing, that minimize the effects of discharge fluctuation. Studies linking hydrologic regime, habitat preference, and population processes, however, are predominantly limited to fish. Information on other sensitive taxa is necessary to facilitate conservation of multispecies assemblages and restoration of biodiversity in degraded river channels. I studied the functional relationship between physical habitat and reproduction of the foothills yellow-legged frog (Rana boylii), a California State Species of Special Concern. From 1992 to 1994, I mapped breeding sites along 5.3 km of the South Fork Eel River in northern California and monitored egg survival to hatching. Frogs selected sites over a range of spatial scales and timed their egg-laying to avoid fluctuations in river stage and current velocity associated with changes in discharge. The main sources of mortality were desiccation and subsequent predation of eggs in a dry year and scour from substrate in wet years, both caused by changes in stage and velocity. At the finest spatial scale, frogs attached eggs to cobbles and boulders at lower than ambient flow velocities. At larger scales, breeding sites were near confluences of tributary drainages and were located in wide, shallow reaches. Clutches laid in relatively narrower and deeper channels had poor survival in rainy as well as dry springs. Most breeding sites were used repeatedly, despite between- and within-year variation in spring stage of the river. This pattern of site selection suggests that conservation of Rana boylii may be enhanced by maintaining or restoring channels with shapes that provide stable habitat over a range of river stages.},
keywords = {amphibians, Anura, frogs, geomorphology, hydrology, oviposition, physical habitat, Rana boylii, reproductive success, river, spatial scale},
pubstate = {published},
tppubtype = {article}
}
Organisms that live in highly variable environments, such as rivers, rely on adaptations to withstand and recover from disturbance. These adaptations include behavioral traits, such as habitat preference and plasticity of reproductive timing, that minimize the effects of discharge fluctuation. Studies linking hydrologic regime, habitat preference, and population processes, however, are predominantly limited to fish. Information on other sensitive taxa is necessary to facilitate conservation of multispecies assemblages and restoration of biodiversity in degraded river channels. I studied the functional relationship between physical habitat and reproduction of the foothills yellow-legged frog (Rana boylii), a California State Species of Special Concern. From 1992 to 1994, I mapped breeding sites along 5.3 km of the South Fork Eel River in northern California and monitored egg survival to hatching. Frogs selected sites over a range of spatial scales and timed their egg-laying to avoid fluctuations in river stage and current velocity associated with changes in discharge. The main sources of mortality were desiccation and subsequent predation of eggs in a dry year and scour from substrate in wet years, both caused by changes in stage and velocity. At the finest spatial scale, frogs attached eggs to cobbles and boulders at lower than ambient flow velocities. At larger scales, breeding sites were near confluences of tributary drainages and were located in wide, shallow reaches. Clutches laid in relatively narrower and deeper channels had poor survival in rainy as well as dry springs. Most breeding sites were used repeatedly, despite between- and within-year variation in spring stage of the river. This pattern of site selection suggests that conservation of Rana boylii may be enhanced by maintaining or restoring channels with shapes that provide stable habitat over a range of river stages.