Blowdown and stand development in a Colorado subalpine forest

1989 ◽  
Vol 19 (10) ◽  
pp. 1218-1225 ◽  
Author(s):  
Thomas T. Veblen ◽  
Keith S. Hadley ◽  
Marion S. Reid ◽  
Alan J. Rebertus
Keyword(s):  
18Th Century ◽  
Lodgepole Pine ◽  
Growth Patterns ◽  
Colorado Front Range ◽  
Subalpine Forest ◽  
Stand Development ◽  
Front Range ◽  
Southern Rocky Mountains ◽  
Engelmann Spruce ◽  
Shade Tolerant Species

Stand development of a subalpine forest in the Colorado Front Range following a ca. 15-ha blowdown was examined by analyzing tree population age structures and radial growth patterns. The stand studied was initiated by a fire at the start of the 18th century and was dominated by a dense population of lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) at the time of blowdown in 1973. Before the blowdown, the subcanopy was characterized by abundant subalpine fir (Abieslasiocarpa (Hook.) Nutt.) and scarce Engelmann spruce (Piceaengelmannii (Parry) Engelm.). Comparison with an adjacent control stand, affected only slightly by the blowdown, indicates that new seedling establishment following the blowdown was slight. Instead, the response was dominated by the release of the subcanopy fir and spruce, resulting in acceleration of the successional replacement of lodgepole pine by these shade-tolerant species. Given the >300 years required for an old-growth fir and spruce stand to develop following catastrophic fire, the likelihood of a major canopy disturbance in the form of blowdown and (or) lethal insect attack is high and should be explicitly incorporated into general explanations of stand development of subalpine forests in the southern Rocky Mountains.

Segregation of allozyme loci in megagametophytes of Engelmann spruce and subalpine fir

Genome ◽  
1988 ◽  
Vol 30 (2) ◽  
pp. 103-107 ◽  
Author(s):  
Kathleen L. Shea
Keyword(s):  
Natural Populations ◽  
Segregation Ratio ◽  
Colorado Front Range ◽  
Abies Lasiocarpa ◽  
Front Range ◽  
Subalpine Fir ◽  
Polymorphic Loci ◽  
Engelmann Spruce ◽  
Low Levels ◽  
Allozyme Loci

Segregation ratios and linkage of 10 allozyme loci were examined in haploid megagametophytes obtained from natural populations of Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa) in the Colorado Front Range. For data pooled over trees, the 1:1 segregation ratio expected at Mendelian loci was obtained for five polymorphic loci in 32 Engelmann spruce trees and for seven polymorphic loci in 40 subalpine fir trees. The Gdh and Idh loci in spruce were very tightly linked: no recombinants were detected among 60 megagametophytes of trees heterozygous for both loci. In fir only the Aco and Pgm-1 loci were linked, with an estimated recombination rate of 0.317 ± 0.073. The low levels of among-tree heterogeneity and of segregation distortion found in these populations suggest that reliable estimates of both genetic variation and outcrossing rates can be obtained using allozyme data from these wind-pollinated species.Key words: segregation, linkage, allozymes, Engelmann spruce, subalpine fir.

Genetic variation between and within populations of Engelmann spruce and subalpine fir

Genome ◽  
1990 ◽  
Vol 33 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Kathleen L. Shea
Keyword(s):  
Genetic Variation ◽  
Genetic Structure ◽  
Genetic Differentiation ◽  
Colorado Front Range ◽  
Abies Lasiocarpa ◽  
Front Range ◽  
Dispersal Patterns ◽  
Subalpine Fir ◽  
Engelmann Spruce ◽  
Inbreeding Coefficients

The genetic structure of Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa) in two adjacent sites in the Colorado Front Range was examined using allozyme data from 21 loci in spruce and 18 loci in fir. The genetic diversity measures of alleles per locus, percent loci polymorphic, and mean heterozygosity did not differ significantly between or within species. However, the observed heterozygosity (0.126 spruce, 0.081 fir) values suggest that Engelmann spruce is more genetically variable than subalpine fir. Mean inbreeding coefficients were twice as high in fir as in spruce (FIS = 0.154 spruce, 0.341 fir). There were significant differences in allele frequencies in both species between and within sites, and among age-classes, with spatial differences greater than temporal differences. F-statistics showed greater genetic differentiation within (FST = 2.3–2.6% spruce, 2.0–2.8% fir) than between sites (FST = 1.7% spruce, 1.3% fir). Both species had higher FST and genetic distance values, yet lower FIS values, for spatial subdivisions within rather than between sites. This pattern suggests that the size of a spatial subdivision, where maximum gene flow is 54 m, approximates the size of the largest panmictic unit. In contrast with studies on other conifers, these results suggest that factors such as differential selection pressures, seed dispersal patterns, and clumped spatial distribution have resulted in genetic differentiation at the microhabitat level in Engelmann spruce and subalpine fir.Key words: genetic variation, genetic structure, allozymes, Engelmann spruce, subalpine fir, microgeographic differentiation.

Strength and persistence of fire-induced soil hydrophobicity under ponderosa and lodgepole pine, Colorado Front Range

2001 ◽  
Vol 15 (15) ◽  
pp. 2877-2892 ◽  
Author(s):  
Edward L. Huffman ◽  
Lee H. MacDonald ◽  
John D. Stednick
Keyword(s):  
Lodgepole Pine ◽  
Colorado Front Range ◽  
Front Range ◽  
Soil Hydrophobicity

Drought-driven disturbance history characterizes a southern Rocky Mountain subalpine forest

2012 ◽  
Vol 42 (9) ◽  
pp. 1649-1660 ◽  
Author(s):  
R. Justin DeRose ◽  
James N. Long
Keyword(s):  
Vegetation Dynamics ◽  
Rocky Mountain ◽  
Subalpine Forest ◽  
Dendroctonus Rufipennis ◽  
Southern Rocky Mountains ◽  
Engelmann Spruce ◽  
Spruce Beetle ◽  
Drought Conditions ◽  
Recent Outbreak ◽  
Species Specific

The view that subalpine forest vegetation dynamics in western North America are “driven” by a particular disturbance type (i.e., fire) has shaped our understanding of their disturbance regimes. In the wake of a recent (1990s) landscape-extent spruce beetle ( Dendroctonus rufipennis Kirby) outbreak in the southern Rocky Mountains, we re-examined the temporal continuity in disturbance types and interactions and the possible role of drought on their occurrence by reconstructing antecedent disturbances for 11 sites across the Markagunt Plateau, southern Utah, USA. Multiple consistent lines of evidence suggested that historic fires were the primary antecedent disturbance, while relatively minor, stand-specific spruce beetle activity occurred later in stand development but prior to the recent outbreak. Unlike the recent outbreak, antecedent fires were spatially and temporally asynchronous over the period examined (~1600–2000). Reconstructed fire events primarily occurred during periods of prolonged drought. Similarly, historic spruce beetle activity, indicated by species-specific tree-ring release, and timing of Engelmann spruce ( Picea engelmannii Parry ex Engelm.) death dates from the recent outbreak were related to drought conditions. Vegetation dynamics on this landscape were strongly driven by historic fires and the recent spruce beetle outbreak, and drought conditions likely influenced the occurrence of both disturbance types.

Tree spatial patterns and stand development along the pine-grassland ecotone in the Colorado Front Range

1999 ◽  
Vol 29 (5) ◽  
pp. 575-584 ◽  
Author(s):  
Joy Nystrom Mast ◽  
Thomas T Veblen
Keyword(s):  
Spatial Autocorrelation ◽  
Spatial Patterns ◽  
Tree Regeneration ◽  
Colorado Front Range ◽  
Tree Age ◽  
Stand Development ◽  
Front Range ◽  
Ripley’S K ◽  
Ripley's K ◽  
Tree Spatial Patterns

Patterns of stand development may be interpreted from spatial analyses, based on variables such as tree age and size, together with past records of climate and disturbance. In the present study, our objective is to examine spatial patterns of tree age and size to determine if they are consistent with the episodic pattern of tree regeneration proposed for ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) and expected changes in tree spatial patterns as cohort patches age. According to our hypothesis, internal patch structure should become less clumped as single cohort patches age due to self-thinning, with few trees attaining dominance in a small patch. In this study, tree spatial patterns in 16 stands of P. ponderosa in the Colorado Front Range are described and related to patterns of stand development. Analytical methods included Ripley's K(t) (a univariate statistic of tree spatial distribution), Ripley's K12(t) (a bivariate statistic of spatial association), and Moran's I (a measure of spatial autocorrelation). Spatial patterns imply establishment of patches of pines followed by self-thinning. Continued stand development results in strong size hierarchies as manifested by stronger spatial autocorrelation of tree age than tree size. Hence, pines exhibit a strong size class hierarchy developed within an even-aged patch.

Genetic and morphological relationships between blue spruce, Picea pungens, and Engelmann spruce, Picea engelmannii, in the Colorado Front Range

1981 ◽  
Vol 59 (11) ◽  
pp. 2088-2094 ◽  
Author(s):  
Jeffry B. Mitton ◽  
Rosemary Andalora
Keyword(s):  
Discriminant Analysis ◽  
Morphological Characters ◽  
Small Degree ◽  
Enzyme Polymorphism ◽  
Colorado Front Range ◽  
Morphological Data ◽  
Front Range ◽  
Sympatric Populations ◽  
Blue Spruce ◽  
Engelmann Spruce

Nine morphological characters and one enzyme polymorphism were used in a study of hybridization of blue and Engelmann spruce in the Front Range of Colorado. Eighty-eight trees were studied in one pure Engelmann spruce population, one pure blue spruce population, and three sympatric populations along an elevational transect. The morphological data were summarized with principal components analysis, but no clusters were evident in the projections. A protein polymorphism indicated a predominance of different alleles in the two species, and none of the most common expected (hybrid) heterozygotes were seen. The protein data allowed unambiguous assignment of individuals to separate groups, and subsequently discriminant analysis was performed. The species could be significantly resolved by discriminant analysis of the morphological traits, but a small degree of overlap between species remained.

Longevity of windthrown logs in a subalpine forest of central Colorado

1998 ◽  
Vol 28 (6) ◽  
pp. 932-936 ◽  
Author(s):  
Peter M Brown ◽  
Wayne D Shepperd ◽  
Stephen A Mata ◽  
Douglas L McClain
Keyword(s):  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Woody Debris ◽  
Subalpine Forest ◽  
Primary Study ◽  
Engelmann Spruce ◽  
Significant Difference ◽  
Central Rocky Mountains ◽  
Study Sites ◽  
Cross Dating

The number of years since tree death for wind-thrown logs of lodgepole pine (Pinus contorta var. latifolia Engelm.) and Engelmann spruce (Picea engelmannii Parry) was used to examine the longevity of this component of coarse woody debris in an old-growth subalpine forest in the central Rocky Mountains. Death dates of downed logs were determined by dendrochronological cross-dating methods. We were able to determine death dates for 73 logs from both species, the oldest being a lodgepole pine dead 139 years ago. Sound lodgepole pine and Engelmann spruce logs lying on the ground persisted for many decades with a majority of their volume intact. No difference was seen in decay classes of logs collected from two primary study sites on opposite (north and south) exposures. There was also no significant difference in decay classes between the two species, although lodgepole pine logs were in general older than Engelmann spruce logs within any decay class. There was little decrease in the specific gravity of wood remaining in logs with time, although there was a corresponding greater loss of wood volume.

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