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.
1999
Levine, Jonathan M.
Indirect facilitation: evidence and predictions from a riparian community Journal Article
In: Ecology, vol. 80, no. 5, pp. 1762-1769, 1999, ISSN: 0012-9658.
Abstract | Links | BibTeX | Tags: Carex, competition, facilitation, facilitation in plant communities, indirect effects, Mimulus, plant competition, riparian plant communities, species diversity
@article{Levine1999b,
title = {Indirect facilitation: evidence and predictions from a riparian community},
author = {Jonathan M. Levine},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Indirect-facilitation-evidence-and-predictions-from-a-riparian-community_Levine_1999.pdf},
doi = {10.1890/0012-9658(1999)080[1762:IFEAPF]2.0.CO;2},
issn = {0012-9658},
year = {1999},
date = {1999-07-00},
journal = {Ecology},
volume = {80},
number = {5},
pages = {1762-1769},
abstract = {Indirect facilitation occurs when the indirect positive effect of one species on another, via the suppression of a shared competitor, is stronger than the direct competitive effect. Although theory predicts that these interactions may be common in assemblages of three or more competitors, experimental studies of this process are rare. Here, I report a study of a northern California riparian community, where I tested the hypothesis that the sedge Carex nudata had direct competitive effects on other plant species, as well as indirect facilitative effects, by suppressing a second competitor, the common monkey-flower Mimulus guttatus. Results of a field experiment, in which I manipulated the presence of Cares and M. guttatus in a factorial design, uncovered three qualitatively different interactions between Carer and three target species. I found evidence of indirect facilitation for the liverwort Conocephalum conicum, such that Carex "facilitated" Conocephalum in the presence of M. guttatus, while Carer competed with Conocephalum in the absence of M. guttatus. Plant distribution patterns supported the widespread occurrence of this interaction. Carer also had an indirect positive effect on the scarlet monkey-flower M. cardinalis, though the magnitude of this effect was similar to direct Carex competition. Lastly, Carex had no influence on the moss Brachythecium frigidum. The mechanisms underlying the plant interactions in this study are discussed and incorporated into a general hypothesis that indirect facilitation among competitors is most important in assemblages of species that vary in competitive mechanism.},
keywords = {Carex, competition, facilitation, facilitation in plant communities, indirect effects, Mimulus, plant competition, riparian plant communities, species diversity},
pubstate = {published},
tppubtype = {article}
}
Indirect facilitation occurs when the indirect positive effect of one species on another, via the suppression of a shared competitor, is stronger than the direct competitive effect. Although theory predicts that these interactions may be common in assemblages of three or more competitors, experimental studies of this process are rare. Here, I report a study of a northern California riparian community, where I tested the hypothesis that the sedge Carex nudata had direct competitive effects on other plant species, as well as indirect facilitative effects, by suppressing a second competitor, the common monkey-flower Mimulus guttatus. Results of a field experiment, in which I manipulated the presence of Cares and M. guttatus in a factorial design, uncovered three qualitatively different interactions between Carer and three target species. I found evidence of indirect facilitation for the liverwort Conocephalum conicum, such that Carex “facilitated” Conocephalum in the presence of M. guttatus, while Carer competed with Conocephalum in the absence of M. guttatus. Plant distribution patterns supported the widespread occurrence of this interaction. Carer also had an indirect positive effect on the scarlet monkey-flower M. cardinalis, though the magnitude of this effect was similar to direct Carex competition. Lastly, Carex had no influence on the moss Brachythecium frigidum. The mechanisms underlying the plant interactions in this study are discussed and incorporated into a general hypothesis that indirect facilitation among competitors is most important in assemblages of species that vary in competitive mechanism.