2000
Levine, Jonathan M.
Complex interactions in a streamside plant community Journal Article
In: Ecology, vol. 81, no. 12, pp. 3431-3444, 2000, ISSN: 0012-9658.
Abstract | Links | BibTeX | Tags: associational defense, Carex, competition, facilitation, Junonia, Mimulus, riparian community
@article{Levine2000,
title = {Complex interactions in a streamside plant community},
author = {Jonathan M. Levine},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Complex-interactions-in-a-streamside-plant-community_Levine_2000.pdf},
doi = {10.1890/0012-9658(2000)081[3431:CIIASP]2.0.CO;2},
issn = {0012-9658},
year = {2000},
date = {2000-12-00},
journal = {Ecology},
volume = {81},
number = {12},
pages = {3431-3444},
abstract = {Ecologists are increasingly finding that complex combinations of competitive and facilitative interactions influence the distribution and abundance of plants. I conducted a two-year field experiment to explore these processes in a streamside community lining the South Fork Eel River in northern California. Specifically, I tested the hypothesis that the sedge Carex nudata provides critical stable substrate for other plants during winter floods and protection from herbivores over the growing season. In addition to these facilitative effects, Carer is also hypothesized to compete with the associated species, and thus limit their size and reproduction.
To evaluate these hypotheses, I followed the performance of transplanted individuals of Mimulus guttatus, M. cardinalis, Juncus covillei, Conocephalum conicum, and Brachythecium frigidum and naturally occurring individuals of Epipactis gigantea on Carer tussocks with dense, thinned, pinned back, or completely clipped Carer stems. The five transplanted species were also planted directly onto the emergent streambed. Though streambed transplants grew as well as those on tussocks over the summer, they experienced significantly greater winter mortality, up to 100%, supporting the hypothesis that tussocks provide a critical stable substrate. In contrast, growing season competition by Carer reduced biomass by over 50% for five of the six species and reduced reproductive performance by over 60%. Also, over the growing season, Carex protected M. guttatus and Epipactis from insect larvae and deer, respectively, reducing herbivory by >75%. Additional results from a deer exclosure treatment showed that the positive effects of this "associational defense" were equal in magnitude to the negative effects of Carer competition on Epipactis biomass. The mechanisms underlying these associational defenses and the implications of my results for the relationship between disturbance and facilitation are discussed. I suggest that regarding plant interactions as combinations of facilitative and competitive components may enhance our understanding of natural communities.},
keywords = {associational defense, Carex, competition, facilitation, Junonia, Mimulus, riparian community},
pubstate = {published},
tppubtype = {article}
}
Ecologists are increasingly finding that complex combinations of competitive and facilitative interactions influence the distribution and abundance of plants. I conducted a two-year field experiment to explore these processes in a streamside community lining the South Fork Eel River in northern California. Specifically, I tested the hypothesis that the sedge Carex nudata provides critical stable substrate for other plants during winter floods and protection from herbivores over the growing season. In addition to these facilitative effects, Carer is also hypothesized to compete with the associated species, and thus limit their size and reproduction.
To evaluate these hypotheses, I followed the performance of transplanted individuals of Mimulus guttatus, M. cardinalis, Juncus covillei, Conocephalum conicum, and Brachythecium frigidum and naturally occurring individuals of Epipactis gigantea on Carer tussocks with dense, thinned, pinned back, or completely clipped Carer stems. The five transplanted species were also planted directly onto the emergent streambed. Though streambed transplants grew as well as those on tussocks over the summer, they experienced significantly greater winter mortality, up to 100%, supporting the hypothesis that tussocks provide a critical stable substrate. In contrast, growing season competition by Carer reduced biomass by over 50% for five of the six species and reduced reproductive performance by over 60%. Also, over the growing season, Carex protected M. guttatus and Epipactis from insect larvae and deer, respectively, reducing herbivory by >75%. Additional results from a deer exclosure treatment showed that the positive effects of this “associational defense” were equal in magnitude to the negative effects of Carer competition on Epipactis biomass. The mechanisms underlying these associational defenses and the implications of my results for the relationship between disturbance and facilitation are discussed. I suggest that regarding plant interactions as combinations of facilitative and competitive components may enhance our understanding of natural communities.
To evaluate these hypotheses, I followed the performance of transplanted individuals of Mimulus guttatus, M. cardinalis, Juncus covillei, Conocephalum conicum, and Brachythecium frigidum and naturally occurring individuals of Epipactis gigantea on Carer tussocks with dense, thinned, pinned back, or completely clipped Carer stems. The five transplanted species were also planted directly onto the emergent streambed. Though streambed transplants grew as well as those on tussocks over the summer, they experienced significantly greater winter mortality, up to 100%, supporting the hypothesis that tussocks provide a critical stable substrate. In contrast, growing season competition by Carer reduced biomass by over 50% for five of the six species and reduced reproductive performance by over 60%. Also, over the growing season, Carex protected M. guttatus and Epipactis from insect larvae and deer, respectively, reducing herbivory by >75%. Additional results from a deer exclosure treatment showed that the positive effects of this “associational defense” were equal in magnitude to the negative effects of Carer competition on Epipactis biomass. The mechanisms underlying these associational defenses and the implications of my results for the relationship between disturbance and facilitation are discussed. I suggest that regarding plant interactions as combinations of facilitative and competitive components may enhance our understanding of natural communities.
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.