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Results for “Canadian Journal of Botany”

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9 recordsLinked to original sources
USGS2001

Genetic and morphologic variation in Phyllodoce empetriformis and Phyllodoce glanduliflora (Ericaceae) in Mount Rainier National Park, Washington

Genetic and morphological diversity of Phyllodoce empetriformis (Sw.) D. Don and Phyllodoce glanduliflora (hook.) Cov. were surveyed in Mount Rainier National Park in the Cascade Mountains of Washington State. Paired populations at high and low elevations were sampled at three study areas between 1720- and 2451-m elevation. Allozyme analysis of four polymorphic loci indicates high levels of genetic diversity within populations ( P. empetriformis = 94.2% and P. glanduliflora = 93.4% of total diversity) and significant differences in allele frequencies among populations and study areas. Individual populations are composed of multiple clones with high ratios of local to widespread genotypes. The proportion of distinguishable clones ranges from 32 to 83% within individual populations. Within individual populations, 18-67% of genotypes were restricted to one population. Patterns of morphologic variation, estimated through measurements of leaf width, leaf length, stem extension, and plant height paralleled those displayed by allozyme analysis. Significant differences were found in leaf width and stem length for P. empetriformis and among greenhouse populations for leaf width ( P. empetriformis ) and leaf length ( P. glanduliflora ). Species conservation strategies for Phyllodoce should concentrate on the maintenance of within-population levels of diversity, protection of adjacent populations, and protection of safe sites for recruitment of new populations.

Washington↗
USGS2001

Ramet spacing of Elymus lanceolatus (thickspike wheatgrass) in response to neighbour density

Many plants exploit patchy resources through clonal foraging. Plants established in field plots were used to determine if Elymus lanceolatus ssp. lanceolatus (Scribner et J.G. Smith) Gould (thickspike wheatgrass) showed a clonal foraging response to neighbour densities, as it had previously shown to patchy soil nutrients. Neighbours consisted of the rhizomatous E. lanceolatus ssp. lanceolatus and the bunchgrass Elymus lanceolatus ssp. wawawaiensis (Scribner et Gould) J.R. Carlson et D.R. Dewey (proposed name), which are both native to the semiarid western U.S.A., and their ratios as well as total densities varied. Rather than an increase in spacing of exploratory ramets at high densities, as expected with clonal foraging, there was a decrease in spacing in both years of the experiment. Fewer target plants produced exploratory ramets at higher densities only in the second year. These reductions in exploratory clonal growth at higher neighbour densities, which were opposite to E . lanceolatus ssp. lanceolatus ' response to low-resource patches, occurred perhaps because soil resource levels were too low overall to support rhizome production, and this condition was more pronounced in the second year. Physical resistance from neighbour roots perhaps also reduced rhizome production. However, rhizome growth may not be beneficial in such cases, and plants may be adapted to produce exploratory rhizomes only when some high-resource patches are encountered by the clone.

Canadian Journal of Botany↗
USGS1985

Growth of submersed macrophyte communities in the St. Clair - Detroit River system between Lake Huron and Lake Erie

Growth of submersed aquatic macrophytes was determined from observation and on the basis of biomass of samples collected from April to November 1978 at seven study sites in a major river system of the Great Lakes, the St. Clair – Detroit river system between Lake Huron and Lake Erie. Growth usually began between April and June, peaked between July and October, and decreased by late November. Maximum biomass at six of the seven sites (118–427 g dry weight m −2 ) was similar or greater than that reported in other rivers at similar latitudes. Seasonal growth of the abundant taxa followed one of three seasonal patterns at each study site: one dominant taxon grew alone; codominant taxa grew sympatrically without species succession; and codominant taxa grew sympatrically with species succession. Differences in growth and seasonal succession of some taxa were apparently caused by the presence or absence of overwintering plant material, competition, and life-cycle differences.

Canadian Journal of Botany↗
USGS1988

Seasonal growth of the exotic submersed macrophyte Nitellopsis obtusa in the Detroit River of the Great Lakes

Seasonal growth and occurrence of an exotic submersed aquatic macrophyte, Nitellopsis obtusa , was monitored at the head of the Detroit River of the Great Lakes from June 1984 to April 1985. Nitellopsis obtusa first appeared in early July, increased in biomass from July to September, remained at relatively high biomass from September to late January, and decreased substantially as ice breakup began in mid-February. By March it had become senescent, lacking chlorophyll and disintegrating easily. Nitellopsis obtusa was therefore available as a source of food and shelter for benthic and juvenile fish populations in late fall and winter, when other macrophytes were absent.

Canadian Journal of Botany↗
USGS1989

Replacement of native oak and hickory tree species by the introduced American chestnut (Castanea dentata) in southwestern Wisconsin

American chestnut was introduced at West Salem, Wisconsin, about 1880 and had begun to replace native tree species in adjacent oak-hickory woodland before 1930. Chestnut is now an important canopy species over about 20 ha of forested ridge extending north and south of the original plantation. A smaller area of less than 5 ha is dominated by chestnut in both the canopy and understory. Chestnut seedlings and small saplings are more numerous along woodland edges and in recently disturbed soil, they are rare in the interior of ungrazed pasture and entirely absent from intensively grazed areas adjacent to chestnut-dominated woodland. Random sampling of recently established seedlings indicates that from 1 to 5 seedlings/(year ∙ ha) became established in undisturbed woodland between 1986 and 1988. The general pattern of chestnut distribution indicates the importance of woodland edges in chestnut propagation and the effects of livestock grazing in excluding chestnut. Replacement of native species by chestnut appears to have occurred in two steps: isolated groups of trees became established at favorable locations, after which many additional chestnut stems became established in the understory. The recent discovery and treatment of blight indicates that the West Salem site may not be available for study of blight-free chestnut in the future.

Wisconsin↗
USGS1991

Genotypic and phenotypic variability of Zostera marina on the west coast of North America

The relation between environmental factors and leaf morphology of Zostera marina L. have long been unclear, primarily because the species is intrinsically variable. The common-garden method was used to determine the genetic, environmental, and interaction components of leaf size variation. Zostera marina consists of several ecotypes with a wide range of phenotypic plasticity. Variation in the morphology of Z . marina was of three types: genetic, accounting for 14% across the localities studied; environmental (phenotypic plasticity along temporal and spatial gradients), accounting for 32%; and interaction between genotype and environmental, acounting for 35%. Five ecotypes were described for the North American Pacific coast: Z . marina L. var. izembekensis Backman, Z . marina L. var. typica Setchell, Z . marina L. var. phillipsii Backman, Z . marina L. var. latifolia Morong, Z . marina L. var. atàm Backman. Temporal variation was due to seasonal phenotypic changes in ecotypes. Zostera marina var. izembekensis showed little seasonal morphological changes; Z . marina var. typica demonstrated minor increase in leaf size in spring and summer. Zostera marina var. phillipsii and Z . marina var. latifolia behaved similarly in that leaf size of both increased markedly in spring through early summer. Zostera marina var. phillipsii is adapted to Hood Canal and Puget Sound while Z . marina var. latifolia occupies the outer coast. Zostera marina var. atàm exhibits sexual reproduction exclusively and is specifically adapted to the Gulf of California.

Canadian Journal of Botany↗
USGS1994

Classification of vegetation communities in which geese rear broods on the Yukon-Kuskokwim Delta, Alaska

Plant communities are described from an area on the Yukon – Kuskokwim (Y-K) delta of Alaska that is used extensively for brood rearing by three species of geese. Earlier studies identified plant species important as food for young geese, but few studies describe or quantify plant communities. We classified species presence or absence information from over 700 quadrats using a two-way indicator species analysis ( TWINSPAN ) and then tested for agreement of signatures on colour infrared air photos with the identified communities. Sedges were found to dominate all but the wettest and driest communities. Most of the brood-rearing area was covered by Carex ramenskii and Carex rariflora meadows, ponds, Carex mackenziei -dominated pond margins, and C . ramenskii and grass levee meadows. Our interpretation of airphotos accurately predicted vegetation community classes, which will facilitate future studies of habitat selection by geese during the time they are rearing young. The TWINSPAN classification was comparable to classifications of studies conducted elsewhere on the Y-K delta. The interpretation of air photos will enable the identification and evaluation of wetland vegetation complexes and potential goose brood-rearing areas away from our study site.

Alaska↗
USGS1997

Perception of neighboring plants by rhizomes and roots: Morphological manifestations of a clonal plant

A previous study showed that clonal morphology of the rhizomatous grass Elymus lanceolatus ssp. lanceolatus (Scibner & J.G. Smith Gould) was influenced more by neighbouring root systems than by the local distribution of nutrients. In this study we determine whether individual rhizomes or roots of E . lanceolatus perceive neighbouring root systems and how this is manifested in morphological responses of E . lanceolatus clones. Elymus lanceolatus was grown in the same bin with Pseudoroegneria spicata (Pursh) A. Love or Agropyron desertorum (Fisch. ex Link) Schult. plants. Elymus lanceolatus was separated from its neighbours by different barriers. The barriers allowed either only E . lanceolatus roots; only a single E . lanceolatus primary rhizome; or both roots and rhizomes to contact the neighbour root system. When only a single E . lanceolatus primary rhizome with potentially developing branching rhizomes made contact with the neighbour, the clonal structure of E . lanceolatus was modified more with P . spicata as the neighbour than with A . desertorum . With root contact of E . lanceolatus alone there was a similar effect with the neighbouring plants, but there was a more marked inhibitory effect on E . lanceolatus clonal growth with P . spicata than with A . desertorum , compared with the treatment with only a single rhizome in contact with the neighbour. Root resource competition in the unconstrained treatment (roots and rhizomes) between neighbouring plant and E . lanceolatus was more apparent with A . desertorum than with P . spicata . This study is one of the first to document that rhizome and root contact of a clonal plant with its neighbours may induce different clonal responses depending on the species of neighbour. Key words : Agropyron desertorum , clonal morphology, Elymus lanceolatus ssp. lanceolatus , plant interference, plant contact, Pseudoroegneria spicata , rhizome structure, root systems.

Canadian Journal of Botany↗
USGS2000

Species richness and abundance of ectomycorrhizal basidiomycete sporocarps on a moisture gradient in the Tsuga heterophylla zone

Sporocarps of epigeous ectomycorrhizal fungi and vegetation data were collected from eight Tsuga heterophylla (Raf.) Sarg. - Pseudotsuga menziesii (Mirb.) Franco stands along a wet to dry gradient in Olympic National Park, Washington, U.S.A. One hundred and fifty species of ectomycorrhizal fungi were collected from a total sample area of 2.08 ha. Over 2 years, fungal species richness ranged from 19 to 67 taxa per stand. Sporocarp standing crop ranged from 0 to 3.8 kg/ha, averaging 0.58 kg/ha, 0.06 kg/ha in spring and 0.97 kg/ha in fall. Sporocarp standing crop and fungal species richness were correlated with precipitation. These results demonstrated that ectomycorrhizal fungal sporocarp abundance and species richness can be partly explained in terms of an environmental gradient.

Canadian Journal of Botany↗