Patterns of clonal occurrence in a mature cottonwood grove along the Oldman River, Alberta

The conservation of the remaining riparian woodlands of western North America will benefit from a better understanding of cottonwood (poplar) regeneration. Following our discrimination of the 67 cottonwood clones present in an island population of 391 trunks, the present investigation characterized the grove's clonal architecture in terms of species, sex, spatial patterns, and beaver impacts. Large clones containing up to 53 trunks occurred near the river channel in areas prone to flooding, scouring, deposition, and beaver damage. Populus section Tacamahaca Spach. species Populus angustifolia James and Populus balsamifera L. produced larger (mean diameter = 9.2 m) clones with more ramets (mean = 6.7) than the section Aigeiros Duby species Populus deltoides Bartr. (7.3 m diameter, 2.7 ramets). The increased clonal nature of the Tacamahaca species is probably adaptive along steeper gradient streams in foothill regions where increased physical disturbance encourages clonal sprouting. Conversely, P. deltoides occurs along more gradually sloped reaches with finer substrates and smoother stage patterns that would favor seedling recruitment. The grove's clonal structure accounted for the female-biased sex ratio among trunks (204 females : 116 males) since the sex ratio was even among genets (49 females : 51 males). Clonality has contributed substantially to regeneration and grove composition, favoring certain genotypes and influencing woodland structural diversity and spatial distributions. Clonal characteristics differ across Alberta's cottonwood species and would influence the distribution of these native trees.Key words: asexual reproduction, beavers, clonality, cottonwoods, Populus, sex.

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Fire induces clonal sprouting of riparian cottonwoods

Canadian Journal of Botany ◽

10.1139/b99-135 ◽

2000 ◽

Vol 77 (11) ◽

pp. 1604-1616 ◽

Cited By ~ 1

Author(s):

Lori A Gom ◽

Stewart B Rood

Keyword(s):

Populus Deltoides ◽

Seedling Recruitment ◽

Adventitious Shoots ◽

Fire Disturbance ◽

Average Height ◽

Populus Balsamifera ◽

Black Cottonwood ◽

Populus Angustifolia ◽

Southern Alberta ◽

Oldman River

The principal native trees in the semiarid regions of southern Alberta are riparian cottonwoods. These include narrowleaf cottonwood, Populus angustifolia James, balsam poplar, Populus balsamifera ssp. balsamifera L., black cottonwood, Populus balsamifera ssp.trichocarpa Torr. & Gray, and prairie cottonwood, Populus deltoides Bartr., and interspecific hybrids. These phreatophytic poplars occur on the moist floodplains along streams and require flood disturbance for seedling recruitment. The present study investigated the responses of cottonwoods to another physical disturbance, fire. Two fires occurred in April 1992, in adjacent groves along the Oldman River at Lethbridge, Alberta. The fires occurred prior to bud flushing and the cottonwoods responded by vigorous sprouting, particularly in the first summer. By September of 1992 about 75% of the burned trees had produced coppice sprouts, new shoots from the remnant stumps. Root suckers, adventitious shoots from the roots of the burned trees, were also common, averaging 1 sucker/3 m2 in the burned zone. Five years after the burns, the number of clonal sprouts was reduced by about half and those had reached an average height of 3 m. Because of the difficulties of species identification for juvenile cottonwoods, sprouts were designated as Populus section Aigeiros (P. deltoides) or section Tacamahaca (the other species). After 5 months, 90% of the sprouting trunks and 80% of the suckers belonged to section Tacamahaca. After 5 years, this ratio had increased to 97% of the sprouting trunks and 98% of the suckers. This indicates that Tacamahaca cottonwoods produced more numerous sprouts with better survival than P. deltoides. This pattern across Populus sections was also observed at seven other cottonwood burn sites in western North America, from northern British Columbia to southern Utah. The Aigeiros cottonwoods, P. deltoides and P. fremontii S. Wats., produced few clonal shoots following fire, whereas Tacamahaca trees sprouted profusely. This study demonstrates that fire disturbance can stimulate clonal regeneration of riparian cottonwoods, particularly of section Tacamahaca.

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Big old cottonwoods

Canadian Journal of Botany ◽

10.1139/b03-065 ◽

2003 ◽

Vol 81 (7) ◽

pp. 764-767 ◽

Cited By ~ 12

Author(s):

Stewart B Rood ◽

Mary Louise Polzin

Keyword(s):

Habitat Structure ◽

Populus Deltoides ◽

Populus Trichocarpa ◽

Thuja Plicata ◽

Populus Balsamifera ◽

Populus Angustifolia ◽

Red Cedar ◽

Riparian Trees ◽

Riparian Woodlands ◽

Thuja Plicata Donn

In studying riparian woodlands along streams across western North America, we observed a grove of exceptionally large and old black cottonwoods, Populus trichocarpa Torr. & A. Gray, along the Elk River in southeastern British Columbia. Situated in a floodplain forest dominated by western red cedar, Thuja plicata Donn ex D. Don, the cottonwoods were up to 2.2 m in diameter, and although heart rot prevented precise aging, increment cores indicated ages of up to 400 years. This demonstrated the potential for substantial longevity of section Tacamahaca cottonwoods (including Populus angustifolia James and Populus balsamifera L.) compared with section Aigeiros species (Populus deltoides Bartr. and Populus fremontii Wats.), which are shorter lived (about 150 year maximum). Very old cottonwoods make distinctive contributions to habitat structure of riparian woodlands and reveal stable floodplain locations that have not been eroded by the river channel for the duration of the trees' lives.Key words: aging, poplars, riparian, trees.

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The discrimination of cottonwood clones in a mature grove along the Oldman River in southern Alberta

Canadian Journal of Botany ◽

10.1139/b99-123 ◽

1999 ◽

Vol 77 (8) ◽

pp. 1084-1094 ◽

Cited By ~ 1

Author(s):

Lori A Gom ◽

Stewart B Rood

Keyword(s):

Interspecific Hybrids ◽

Clonal Propagation ◽

Populus Deltoides ◽

Leaf Shape ◽

Populus Balsamifera ◽

Balsam Poplar ◽

Populus Angustifolia ◽

Southern Alberta ◽

Gall Mite ◽

Oldman River

In southwestern Alberta, the prairie cottonwood (Populus deltoides Bartr.), balsam poplar (Populus balsamifera L.), narrowleaf cottonwood (Populus angustifolia James), and interspecific hybrids provide the foundation of the biologically rich riparian forests. In addition to seedling-based reproduction, these cottonwoods are capable of clonal propagation, the extent of which is poorly understood. To investigate clonality in mature cottonwoods, a method for clone recognition was investigated. Between 1995 and 1997, the morphology and phenology of each tree in a mature cottonwood grove along the Oldman River were characterized. In decreasing order of utility, the characteristics most effective in revealing clones were sex, leaf shape, floral (inflorescence) phenology, and leaf phenology: flushing, senescence, and abscission. Independent traits of poplar bud gall mite (Aceria parapopuli Keifer) susceptibility and trunk architecture were less useful in clone delineation but validated the clonal determinations. Based on the analysis, the grove's 391 trunks (>10 cm diameter) included 115 genotypes, 48 single-trunked individuals, and 67 multiple-trunked clones. The clones (genets) contained from 2 to 53 trunks (ramets). It was found that 88% of trunks belonged to clonal groups, a proportion that was higher than anticipated. The extensive capacity for clonal recruitment should thus be considered in analyses of cottonwood reproductive ecology and cottonwood conservation and restoration programs.Key words: asexual reproduction, clone delineation, cottonwoods, morphology, phenology, Populus.

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Instream flows and the decline of riparian cottonwoods along the St. Mary River, Alberta

Canadian Journal of Botany ◽

10.1139/b95-136 ◽

1995 ◽

Vol 73 (8) ◽

pp. 1250-1260 ◽

Cited By ~ 109

Author(s):

Stewart B. Rood ◽

John M. Mahoney ◽

David E. Reid ◽

Leslie Zilm

Keyword(s):

Water Table ◽

Riparian Vegetation ◽

River Flow ◽

Populus Deltoides ◽

General Pattern ◽

Populus Balsamifera ◽

Stream Flows ◽

Populus Angustifolia ◽

Instream Flows ◽

Narrow Bands

Completed in 1951, the St. Mary Dam enables water storage and diversion for irrigation; river flows downstream are consequently dramatically reduced during summer months. To assess historical changes in the abundance of riparian cottonwoods (Populus balsamifera, Populus angustifolia, and a few Populus deltoides), airphoto analyses were conducted for 40-km river reaches upstream and downstream from the dam and along adjacent dammed and undammed rivers. Cottonwoods along the lower St. Mary River are confined by steep-walled canyons to narrow bands and consequently analyses of the lineal river distance associated with cottonwoods were conducted. These revealed a 68% decline from 1951 to 1985. The decline was progressive, with 28.9, 27.6, 15.1, and 7.6% of the reach associated with cottonwoods in 1951, 1961, 1981, and 1985, respectively. Ground surveys from 1985 to 1994 indicated further decline after 1985 and an absence of cottonwood seedlings and saplings. Cottonwood stands upstream from the St. Mary Dam and along adjacent rivers are more extensive and analyses of the areal extent of stands were consequently appropriate. These indicated minor change along the upper St. Mary (−0.5%), the upper (+1.9%) and lower Waterton (+3.5%), and the upper Belly (−9.1%) rivers, and an increase in forest abundance along the lower Belly River (+52.2%), between 1951 and 1985. Thus, the decline of cottonwoods along the lower St. Mary River was not symptomatic of a general pattern of decline in the region. Analyses of historical stream flows indicated that the cottonwood mortality was drought induced as a result of insufficient flows during the hot, dry summer periods and abrupt flow reductions following the high-flow period in the late spring. The riparian water table was determined to be closely coordinated with river stage, as changes in river elevation were followed by quantitatively similar changes in water table depth. Along the St. Mary River, reduced sedimentation downstream from the dam was not considered to be responsible for the cottonwood decline. The historically sparse cottonwood abundance along the lower St. Mary River may have reflected environmental conditions that were naturally only marginally suitable, and those groves may have been particularly vulnerable to the impacts of river flow regulation. Key words: Populus, cottonwoods, instream flows, mortality, riparian vegetation.

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Clonal reproduction of riparian cottonwoods in southern Alberta

Canadian Journal of Botany ◽

10.1139/b94-217 ◽

1994 ◽

Vol 72 (12) ◽

pp. 1766-1774 ◽

Cited By ~ 53

Author(s):

Stewart B. Rood ◽

Craig Hillman ◽

Trevor Sanche ◽

John M. Mahoney

Keyword(s):

Populus Deltoides ◽

Hybrid Poplar ◽

Adventitious Shoots ◽

Clonal Reproduction ◽

Populus Balsamifera ◽

Populus Angustifolia ◽

Southern Alberta ◽

A Site ◽

Oldman River ◽

Root Suckers

From 1990 to 1993, 690 small cottonwood saplings were excavated along four rivers in the Oldman River Basin to determine their method of origin. Overall, 52% began as seedlings while 48% originated through clonal mechanisms, of which 30% (of the total) were root suckers, i.e., adventitious shoots from preexisting roots, and 18% were shoot suckers, i.e., new shoots originating from buried shoots. The shoot suckers arose primarily through (i) flood training, i.e., new shoot emergence from young shoots that had been toppled and buried during flood events, and (ii) shoot regrowth following decapitation by ice scouring or animal browsing. Only two saplings originated through cladoptosis, propagation from excised shoot fragments. The proportion of seedlings versus clonally established shoots varied somewhat across years and sites. Within a site, saplings near the river's edge were more commonly seedlings, whereas saplings further from the river were more commonly root suckers. Three cottonwood species occurred in the forests studied and their reproductive strategies varied somewhat. Unlike the balsam poplar (Populus balsamifera), narrowleaf cottonwood (Populus angustifolia), and interspecific hybrids, the prairie cottonwood (Populus deltoides) did not propagate through root suckers; all species produced seedlings and shoot suckers. This study demonstrates that clonal reproduction has the potential to contribute to the regeneration of riparian cottonwood forests in southern Alberta. The contribution through clonal propagation complicates the forest population structure and should be considered in programs to conserve the remaining riparian cottonwood forests in southern Alberta and elsewhere in North America. Key words: Populus, cottonwoods, hybrid poplar, reproduction, clones, suckering, seedlings.

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A lack of heterosis in natural poplar hybrids from southern Alberta

Canadian Journal of Botany ◽

10.1139/b93-005 ◽

1993 ◽

Vol 71 (1) ◽

pp. 37-42 ◽

Cited By ~ 12

Author(s):

John S. Campbell ◽

John M. Mahoney ◽

Stewart B. Rood

Keyword(s):

Shoot Growth ◽

Populus Deltoides ◽

Populus Balsamifera ◽

Hybrid Swarm ◽

Basal Diameter ◽

Populus Angustifolia ◽

Southern Alberta ◽

Order Of Magnitude ◽

Wet Weight ◽

Shoot Growth Rate

Shoot cuttings were collected from 56 native poplars along 11 rivers and creeks in southwestern Alberta, a region where Populus angustifolia, Populus balsamifera (sspp. balsamifera and trichocarpa), and Populus deltoïdes form a disectional, trispecific hybrid swarm. Cuttings were rooted and established in an irrigated nursery plot. After 3 years, stem diameters and heights were measured from 381 trees and whole shoots were harvested from 74 trees to establish a regression equation relating basal diameter and shoot wet weight. Shoot wet weight varied by more than an order of magnitude across the clones, and P. angustifolia clones tended to grow more slowly than clones of the other two species. There was no significant correlation between shoot growth rate and the degree of hybridization, as determined by a prior multivariate analysis of leaf form that has been substantiated by chemotaxonomic data. Thus, the interspecific hybrids were not generally more vigorous than clones with leaf forms typical of the parental species P. deltoides or P. balsamifera. Conversely, in the same environment, artificial hybrids of P. deltoides from Illinois and P. balsamifera (ssp. trichocarpa) from Washington expressed heterosis. It is theorized that introgressive genetic exchange accompanying the natural interbreeding of these three poplar species in southern Alberta minimizes their genetic distance, preventing heterosis. Key words: heterosis, hybridization, poplars, Populus, biomass.

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No room for males in caves: Female‐biased sex ratio in subterranean amphipods of the genus Niphargus

Journal of Evolutionary Biology ◽

10.1111/jeb.13917 ◽

2021 ◽

Author(s):

Ester Premate ◽

Špela Borko ◽

Simona Kralj‐Fišer ◽

Michael Jennions ◽

Žiga Fišer ◽

...

Keyword(s):

Sex Ratio ◽

Biased Sex Ratio

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Male-biased sex ratio in Argulus canadensis Wilson, 1916 (Crustacea: Branchiura) ectoparasitic on sticklebacks

Canadian Journal of Zoology ◽

10.1139/z89-296 ◽

1989 ◽

Vol 67 (8) ◽

pp. 2078-2080 ◽

Cited By ~ 3

Author(s):

Robert Poulin ◽

Gerard J. FitzGerald

Keyword(s):

Salt Marsh ◽

Sex Ratio ◽

Laboratory Experiments ◽

Fish Predation ◽

Reproductive Behaviour ◽

Egg Deposition ◽

Alternative Hypotheses ◽

Biased Sex Ratio ◽

The Difference ◽

Fish Hosts

Females of the ectoparasitic crustacean Argulus canadensis must leave their fish hosts at least temporarily to deposit their eggs on the substrate. To test the hypothesis that this difference in reproductive behaviour between the two sexes could result in male-biased sex ratios on their stickleback hosts, we sampled sticklebacks in tide pools of a Quebec salt marsh from early July to early September 1986. During this period, fish harboured significantly more male than female A. canadensis. Laboratory experiments were done to test two alternative hypotheses offered to explain this biased sex ratio. The first hypothesis was that male A. canadensis were more successful than females in attacking their stickleback hosts; however, we found no differences in attack success on their hosts between the two parasite sexes. The second hypothesis was that sticklebacks ate more female than male A. canadensis. Although males were less vulnerable to fish predation than females, the difference was not significant. We conclude that sexual differences in reproductive behaviour, i.e., egg deposition behaviour of females, can account for the male-biased sex ratio of A. canadensis on sticklebacks.

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