2001
Levine, Jonathan M.
Local interactions, dispersal, and native and exotic plant diversity along a California stream Journal Article
In: Oikos, vol. 95, no. 3, pp. 397-408, 2001, ISSN: 0030-1299.
Abstract | Links | BibTeX | Tags: biodiversity, community invasibility, ecosystem, invasion resistance, mimulus-guttatus, patterns, populations, regional processes, seed dispersal, species richness
@article{Levine2001,
title = {Local interactions, dispersal, and native and exotic plant diversity along a California stream},
author = {Jonathan M. Levine},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Local-Interactions-Dispersal-and-Native-and-Exotic-Plant-Diversity-along-a-California-Stream_Levine_2001.pdf},
doi = {10.1034/j.1600-0706.2001.950304.x},
issn = {0030-1299},
year = {2001},
date = {2001-12-00},
journal = {Oikos},
volume = {95},
number = {3},
pages = {397-408},
abstract = {Although the species pool, dispersal, and local interactions all influence species diversity, their relative importance is debated. I examined their importance in controlling the number of native and exotic plant species occupying tussocks formed by the sedge Carex nudata along a California stream. Of particular interest were the factors underlying a downstream increase in plant diversity and biological invasions. I conducted seed addition experiments and manipulated local diversity and cover to evaluate the degree to which tussocks saturate with species, and to examine the roles of local competitive processes, abiotic factors, and seed supply in controlling the system-wide patterns.
Seeds of three native and three exotic plants sown onto experimentally assembled tussock communities less successfully established on tussocks with a greater richness of resident plants. Nonetheless, even the most diverse tussocks were somewhat colonized, suggesting that tussocks are not completely saturated with species. Similarly, in an experiment where I sowed seeds onto natural tussocks along the river, colonization increased two- to three-fold when I removed the resident species. Even on intact tussocks, however, seed addition increased diversity, indicating that the tussock assemblages are seed limited. Colonization success on cleared and uncleared tussocks increased downstream from km 0 to km 3 of the study site, but showed no trends from km 3 to km 8. This suggests that while abiotic and biotic features of the tussocks may control the increase in diversity and invasions from km 0 to km 3, similar increases from km 3 to km 8 are more likely explained by potential downstream increases in seed supply. The effective water dispersal of seed mimics and prevailingly downstream winds indicated that dispersal most likely occurs in a downstream direction. These results suggest that resident species diversity, competitive interactions, and seed supply similarly influence the colonization of native and exotic species.},
keywords = {biodiversity, community invasibility, ecosystem, invasion resistance, mimulus-guttatus, patterns, populations, regional processes, seed dispersal, species richness},
pubstate = {published},
tppubtype = {article}
}
Although the species pool, dispersal, and local interactions all influence species diversity, their relative importance is debated. I examined their importance in controlling the number of native and exotic plant species occupying tussocks formed by the sedge Carex nudata along a California stream. Of particular interest were the factors underlying a downstream increase in plant diversity and biological invasions. I conducted seed addition experiments and manipulated local diversity and cover to evaluate the degree to which tussocks saturate with species, and to examine the roles of local competitive processes, abiotic factors, and seed supply in controlling the system-wide patterns.
Seeds of three native and three exotic plants sown onto experimentally assembled tussock communities less successfully established on tussocks with a greater richness of resident plants. Nonetheless, even the most diverse tussocks were somewhat colonized, suggesting that tussocks are not completely saturated with species. Similarly, in an experiment where I sowed seeds onto natural tussocks along the river, colonization increased two- to three-fold when I removed the resident species. Even on intact tussocks, however, seed addition increased diversity, indicating that the tussock assemblages are seed limited. Colonization success on cleared and uncleared tussocks increased downstream from km 0 to km 3 of the study site, but showed no trends from km 3 to km 8. This suggests that while abiotic and biotic features of the tussocks may control the increase in diversity and invasions from km 0 to km 3, similar increases from km 3 to km 8 are more likely explained by potential downstream increases in seed supply. The effective water dispersal of seed mimics and prevailingly downstream winds indicated that dispersal most likely occurs in a downstream direction. These results suggest that resident species diversity, competitive interactions, and seed supply similarly influence the colonization of native and exotic species.
Seeds of three native and three exotic plants sown onto experimentally assembled tussock communities less successfully established on tussocks with a greater richness of resident plants. Nonetheless, even the most diverse tussocks were somewhat colonized, suggesting that tussocks are not completely saturated with species. Similarly, in an experiment where I sowed seeds onto natural tussocks along the river, colonization increased two- to three-fold when I removed the resident species. Even on intact tussocks, however, seed addition increased diversity, indicating that the tussock assemblages are seed limited. Colonization success on cleared and uncleared tussocks increased downstream from km 0 to km 3 of the study site, but showed no trends from km 3 to km 8. This suggests that while abiotic and biotic features of the tussocks may control the increase in diversity and invasions from km 0 to km 3, similar increases from km 3 to km 8 are more likely explained by potential downstream increases in seed supply. The effective water dispersal of seed mimics and prevailingly downstream winds indicated that dispersal most likely occurs in a downstream direction. These results suggest that resident species diversity, competitive interactions, and seed supply similarly influence the colonization of native and exotic species.
Hunter, John C.; Barbour, Michael G.
Through-growth by Pseudotsuga menziesii: A mechanism for change in forest composition without canopy gaps Journal Article
In: Journal of Vegetation Science, vol. 12, no. 4, pp. 445-452, 2001, ISSN: 1100-9233.
Abstract | Links | BibTeX | Tags: acer-saccharum, competition, disturbance, light, morphology, northern California, patterns, recruitment, stands, trees
@article{Hunter2001,
title = {Through-growth by Pseudotsuga menziesii: A mechanism for change in forest composition without canopy gaps},
author = {John C. Hunter and Michael G. Barbour},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Through-Growth-by-Pseudotsuga-menziesii-A-Mechanism-for-Change-in-Forest-Composition-without-Canopy-Gaps_Hunter_Barbour_2001.pdf},
doi = {10.2307/3236996},
issn = {1100-9233},
year = {2001},
date = {2001-08-00},
journal = {Journal of Vegetation Science},
volume = {12},
number = {4},
pages = {445-452},
abstract = {exception. In California's Pseudotsuga-mixed hardwood forests, crowns of Pseudotsuga menziesii (Douglas fir) are within those of angiosperm trees (Arbutus menziesii and Quercus species). In the forests we examined, every Pseudotsuga was younger and all but one were growing more rapidly in girth than the Arbutus or Quercus whose crown it had penetrated. Furthermore, as saplings. the Pseudotsuga had grown at rates between those of suppressed saplings and canopy dominants, The recruitment of emergent Pseudotsuga substantially alters these canopies because of the large size Pseudotsuga attains. Given the density of Pseudotsuga growing in canopy crowns, such recruitment is likely. As a mechanism of recruitment, this through-growth differs from gap recruitment in that the turnover of canopy trees is determined by an understory species' growth rate rather than the overstory species' longevity, and community attributes may change rapidly by replacement of canopy dominants with a dissimilar species. Pseudotsuga could grow through the canopy because of its greater potential height (> 60m vs. 20-40m for the angio-perms). narrower crown and its branches suffering less mechanical damage than those of the angiosperms. In general, resource levels in the understory, canopy height, and interspecific differences in maximum height and crown architecture all influence the likelihood of through-growth. Therefore, for vegetation types whose dominants differ substantially in growth form, through-growth may be a mechanism for rapid ecosystem change.},
keywords = {acer-saccharum, competition, disturbance, light, morphology, northern California, patterns, recruitment, stands, trees},
pubstate = {published},
tppubtype = {article}
}
exception. In California’s Pseudotsuga-mixed hardwood forests, crowns of Pseudotsuga menziesii (Douglas fir) are within those of angiosperm trees (Arbutus menziesii and Quercus species). In the forests we examined, every Pseudotsuga was younger and all but one were growing more rapidly in girth than the Arbutus or Quercus whose crown it had penetrated. Furthermore, as saplings. the Pseudotsuga had grown at rates between those of suppressed saplings and canopy dominants, The recruitment of emergent Pseudotsuga substantially alters these canopies because of the large size Pseudotsuga attains. Given the density of Pseudotsuga growing in canopy crowns, such recruitment is likely. As a mechanism of recruitment, this through-growth differs from gap recruitment in that the turnover of canopy trees is determined by an understory species’ growth rate rather than the overstory species’ longevity, and community attributes may change rapidly by replacement of canopy dominants with a dissimilar species. Pseudotsuga could grow through the canopy because of its greater potential height (> 60m vs. 20-40m for the angio-perms). narrower crown and its branches suffering less mechanical damage than those of the angiosperms. In general, resource levels in the understory, canopy height, and interspecific differences in maximum height and crown architecture all influence the likelihood of through-growth. Therefore, for vegetation types whose dominants differ substantially in growth form, through-growth may be a mechanism for rapid ecosystem change.
1995
Power, Mary E.; Sun, Adrian; Parker, Gary; Dietrich, William E.; Wootton, J. Timothy
Hydraulic food chain models Journal Article
In: BioScience, vol. 45, no. 3, pp. 159-167, 1995, (See stable URL attached; file size exceeds maximum allowable for Angelo.).
Links | BibTeX | Tags: consequences, dynamics, ecosystems, food webs, hetergeneity, patterns, productivity, Southern Ontario, STREAM, top-down
@article{Power1995b,
title = {Hydraulic food chain models},
author = {Mary E. Power and Adrian Sun and Gary Parker and William E. Dietrich and J. Timothy Wootton},
url = {http://www.jstor.org/stable/1312555},
doi = {10.2307/1312555},
year = {1995},
date = {1995-03-00},
journal = {BioScience},
volume = {45},
number = {3},
pages = {159-167},
note = {See stable URL attached; file size exceeds maximum allowable for Angelo.},
keywords = {consequences, dynamics, ecosystems, food webs, hetergeneity, patterns, productivity, Southern Ontario, STREAM, top-down},
pubstate = {published},
tppubtype = {article}
}