Reconstruction of mixed hemlock–spruce stands in coastal southeast Alaska

1991 ◽  
Vol 21 (5) ◽  
pp. 643-654 ◽  
Author(s):  
Robert L. Deal ◽  
Chadwick Dearing Oliver ◽  
Bernard T. Bormann
Keyword(s):  
Survival Rates ◽  
Growth Patterns ◽  
Organic Substrates ◽  
Southeast Alaska ◽  
Dominant Position ◽  
Development Patterns ◽  
Multiple Generation ◽  
Spruce Stands ◽  
Wind Throw ◽  
Sheer Number

Stands of western hemlock (Tsugaheterophylla (Raf.) Sarg.) and Sitka spruce (Piceasitchensis (Bong.) Carr.) on low-elevation, upland sites in coastal southeast Alaska develop as single-generation stands after stand-replacing disturbances and as multiple-generation stands after minor disturbances. Both stand types were studied. Spruce grew rapidly after major and minor windthrow events and reached the mid to upper canopy of the stand. Hemlock showed variable growth patterns and occupied both upper and lower canopy positions. Unlike forested regions containing more tree species, the species compositions and stand structures were similar among both the single- and multiple-generation stands. Hemlock and spruce occupied unique yet similar canopy and stand structural positions in both single- and multiple-generation stands because they had distinctly different regeneration and development patterns. Regardless of the frequency or intensity of the disturbance, spruce usually regenerated on mineral or mixed-soil microsites created by wind-throw events, and hemlock usually regenerated on organic substrates. Hemlock regeneration was prolific and tended to dominate sites by sheer number. Mortality rates were extremely high, but the large number of hemlock seedlings guaranteed many surviving stems. Spruce regeneration was much lower, but this species had higher survival rates and generally more rapid height growth. An important stand component was the advance hemlock regeneration that existed prior to the new stand; they formed a significant and dominant position in the future stand.

Croissance en hauteur à long terme de la régénération préétablie dans des pessières noires boréales régénérées par marcottage, au Québec

1992 ◽  
Vol 22 (4) ◽  
pp. 613-621 ◽  
Author(s):  
Raynald Paquin ◽  
René Doucet
Keyword(s):  
Growth Rate ◽  
Black Spruce ◽  
Height Growth ◽  
Growth Patterns ◽  
Dominant Position ◽  
Clear Cutting ◽  
Effective Age ◽  
Second Growth ◽  
Spruce Stands ◽  
To Come

Height-growth patterns of black spruce (Piceamariana (Mill.) B.S.P.) in the boreal forest were studied in layer-origin stands released by clear-cutting in the first half of this century. Most stems responded to release brought about by clear-cutting of the main stand. Initially, small stems responded more rapidly and more strongly, but their height-growth rate culminated between 20 and 30 years following release, the same period when height-growth rate culminated for the taller, older stems. After the culmination period, growth rates were independent of height at the time of release. Consequently, the taller stems at time of release were able to maintain their dominant position. Height growth over the recent years indicates that this position could be maintained in the years to come, and even indefinitely. It seems that second-growth black spruce stands behave like even-aged stands despite their uneven-aged structure. Consequently, years since release and stem height are more accurate measures of stem effective age than total age. Moreover, the taller stems in the understory, which are usually considerably older, should be considered to be as valuable as smaller regeneration when a stand is cut.

scholarly journals Maximum Stand-Density Index of 40 Western Hemlock–Sitka Spruce Stands in Southeast Alaska

2007 ◽  
Vol 22 (2) ◽  
pp. 99-104 ◽  
Author(s):  
Nathan J. Poage ◽  
David D. Marshall ◽  
Michael H. McClellan
Keyword(s):  
Basal Area ◽  
Stand Density ◽  
Site Factors ◽  
Southeast Alaska ◽  
Spruce Stands ◽  
The Mean ◽  
Stand Density Index ◽  
Over Time ◽  
Stand Basal Area ◽  
Species Proportion

Abstract Reineke's (1933) maximum stand-density index (SDImax) was determined for 40 unthinned, fully stocked, even-aged, hemlock-spruce stands in southeast Alaska. A nonlinear model was used to identify objectively the linear portions of the stands' self-thinning trajectories for analysis. The objectives of the present study were (1) to use the modeled slopes and intercepts to determine the mean SDImax of the stands and (2) to identify stand and site factors associated with the variability observed in SDImax. The mean SDImax of the 40 hemlock-spruce stands in southeast Alaska was 619. Individually, none of the stand or site factors examined accounted for >30% of the variability observed in SDImax when all 40 stands were analyzed together. Although the spruce proportion of total stand basal area of most stands increased over time and the hemlock proportion of total stand basal area of most stands decreased over time, SDImax was not related to species proportion or changes in species proportion over time.

Early establishment and vegetative growth of understory species in the western hemlock – Sitka spruce forests of southeast Alaska

1989 ◽  
Vol 67 (2) ◽  
pp. 318-326 ◽  
Author(s):  
John C. Tappeiner II ◽  
Paul B. Alaback
Keyword(s):  
Solar Radiation ◽  
Seedling Establishment ◽  
Seedling Survival ◽  
Survival Rates ◽  
Field Tests ◽  
Southeast Alaska ◽  
Young Stand ◽  
Cornus Canadensis ◽  
Clonal Development ◽  
Actual Field

To determine how Vaccinium alaskaense, Cornus canadensis, Coptis asplenifolia, Tiarella trifoliata, and Rubus pedatus invade and maintain themselves in conifer forests, we conducted experiments on seed germination and seedling survival and examined clonal development in old-growth, young-growth, and 4- to 6-year-old stands. Seed of all species germinated well in laboratory and field tests (average 23 – 90%), but low germination rates of C. canadensis and T. trifoliata under actual field conditions may retard their invasion of young stands. Survival of all species at 3 and 4 years was lower in the young stand (40 years) than in the old stand (250 + years) and may be related to incident solar radiation. Regressions of the percentage of survival on percentage of transmitted solar radiation were significant (P ≤ 0.05) for all species except C. canadensis. Seed predation and type of seedbed (moss, logs, duff) had little effect on germination and survival rates. Average annual rhizome or stolon growth was slower in the young stand (1 – 3 cm) than in the old stand (1 – 34 cm). In the clearcut, clones had dense foliage because of shorter internodes and more leaves per node and annual rhizome and stolon growth averaged 77 – 160 cm. Both seedling establishment among clones and continual clonal expansion maintain species in old stands, while invasion in young stands is primarily by seedling establishment.

Melanocytic Nevi In Sentinel Lymph Nodes - Association With Cutaneous Nevi And Clinical Relevance In Patients With Cutaneous Melanomas

2021 ◽  
Author(s):  
Lutz Kretschmer ◽  
Viktor Schnabel ◽  
Christian Kromer ◽  
Christoph Bauer-Büntzel ◽  
Annika Richter ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Lymph Nodes ◽  
Regression Models ◽  
Survival Rates ◽  
Growth Patterns ◽  
Multivariate Logistic Regression ◽  
Exact Test ◽  
Melanocytic Nevi ◽  
Logistic Regression Models ◽  
Melanoma Patients

Abstract Purpose: Melanocytic nevi in lymph nodes (NNs) are an important histological differential diagnosis of initial sentinel lymph node (SN) metastasis in melanoma. Our aim was to associate NN in SNs with clinicopathologic features and survival rates in 1 250 patients with SN biopsy for melanoma. Methods: To compare patients with present and absent NN, we used Fisher's exact test, Mann-Whitney U test, and multivariate logistic regression models in this retrospective observational study based on a prospectively maintained institutional database.Results: NN prevalence in axillary, cervical, and groin SNs was 16.5%, 19.4%, and 9.8%, respectively. NN were observed in combination with all growth patterns of melanoma, but more frequently when the primary was histologically associated with a cutaneous nevus. We observed a decreasing NN prevalence with increasing SN metastasis diameter. Multiple logistic regression determined a significantly increased NN probability for SNs of the neck or axilla, for individuals with ≥50 cutaneous nevi, midline primary melanomas, and for individuals who reported non-cutaneous malignancies in their parents. Cancer in parents was also significantly more frequently reported by melanoma patients who had more than 50 cutaneous nevi. In SN-negative patients, NN indicated a tendency for slightly lower melanoma-specific survival.Conclusions: We found a highly significant association between NN diagnosis and multiple cutaneous nevi and provided circumstantial evidence that cutaneous nevi in the drainage area of lymph nodes are particularly important. The trend toward lower melanoma-specific survival in SN-negative patients with NN suggests that careful differentiation of SN metastases is important.

Demography of Peromyscus maniculatus populations in seral stages of coastal coniferous forest in southeast Alaska

1981 ◽  
Vol 59 (6) ◽  
pp. 1045-1061 ◽  
Author(s):  
Beatrice Van Horne
Keyword(s):  
Peromyscus Maniculatus ◽  
Adult Population ◽  
Survival Rates ◽  
Coniferous Forest ◽  
Habitat Type ◽  
High Density ◽  
Adult Males ◽  
Southeast Alaska ◽  
High Density Population ◽  
Density Population

Population dynamics of Peromyscus maniculatus hylaeus in seral stages of spruce–hemlock forest in southeast Alaska were investigated during three consecutive reproductive seasons. Two types of high density population were observed. Breeding activity in both types ended early in the season. The first type consisted of a largely adult population with high year to year constancy in overall density and associated breeding and survival parameters. Adult female survival was high. Adult breeding males were heavy. Survival of pretrappable animals was low, although growth and survival rates of juveniles were similar to or higher than those in the other populations.The second type of high density population occurred on two grids in late summer of 1979, and consisted largely of nonbreeding juvenile young of the year. It resulted from unusually early breeding by a small population of overwintered adults. Despite large differences in habitat type and population density, home range size was similar between years and grids. Adult males had larger home ranges than did adult females or juveniles.

NEW FIRM GROWTH AND DEVELOPMENT: A REPLICATION AND EXTENSION OF REYNOLDS’ RESEARCH

1996 ◽  
Vol 04 (01) ◽  
pp. 19-36 ◽  
Author(s):  
J.B. ARBAUGH ◽  
DONALD L. SEXTON
Keyword(s):  
Growth Model ◽  
Growth And Development ◽  
Firm Growth ◽  
New Ventures ◽  
Growth Patterns ◽  
Development Patterns ◽  
New Model ◽  
Significant Growth ◽  
New Firm

A study of 323 new ventures in Ohio supports Reynolds’ findings of an earlier study in Pennsylvania, namely: firms tend to follow one of four different growth patterns, only one of which includes significant growth; most firms do not experience growth beyond their first year’s sales; and there are no significant correlations between age of the firm and annual sales. The results support a new model of firm growth which empirically invalidates the metamorphic growth model. The study concludes by identifying significant differences in operational and strategic emphases between the development patterns.

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