Relations between red alder composition and understory vegetation in young mixed forests of southeast Alaska

2006 ◽  
Vol 36 (3) ◽  
pp. 738-748 ◽  
Author(s):  
Thomas A Hanley ◽  
Robert L Deal ◽  
Ewa H Orlikowska
Keyword(s):  
Carrying Capacity ◽  
Basal Area ◽  
Picea Sitchensis ◽  
Understory Vegetation ◽  
Wildlife Habitat ◽  
Red Alder ◽  
Southeast Alaska ◽  
Net Production ◽  
Understory Biomass ◽  
Young Growth

Interest in mixed red alder (Alnus rubra Bong.) – conifer young-growth stands has grown in southeast Alaska, USA, because they appear to provide much more productive understory vegetation and wildlife habitat than do similar-aged pure conifer stands. We studied understory vegetation in nine even-aged young-growth stands (38–42 years old) comprising a gradient of red alder – conifer overstory composition, with red alder ranging from 0% to 86% of stand basal area. Conifers were Sitka spruce (Picea sitchensis (Bong.) Carr.), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and western redcedar (Thuja plicata Donn ex D. Don). We measured understory biomass and net production (current annual growth) in each stand by species and plant part and estimated carrying capacity for black-tailed deer (Odocoileus hemionus sitkensis Cowan) with a food-based habitat model. Highly significant positive relations (P < 0.002) were found between red alder basal area and all of the following: total understory biomass (r2 = 0.743), net production of shrubs (r2 = 0.758) and herbs (r2 = 0.855), and summer carrying capacity for deer (r2 = 0.846). The high correlation between red alder and herbaceous production is especially important, because herbs are least abundant and most difficult to maintain in young-growth conifer forests of this region. Red alder offers prospects for increasing understory vegetation biomass and its food value for deer and other wildlife when included as a hardwood overstory species in mixed hardwood–conifer young-growth forests.

Effects on understory biomass and forage 8–10 years after precommercial thinning of Sitka spruce – western hemlock stands in southeast Alaska

2020 ◽  
Vol 50 (2) ◽  
pp. 215-225
Author(s):  
Justin S. Crotteau ◽  
Annelise Z. Rue-Johns ◽  
Jeffrey C. Barnard
Keyword(s):  
Forest Type ◽  
Sitka Spruce ◽  
Picea Sitchensis ◽  
Wildlife Habitat ◽  
Western Hemlock ◽  
Stand Age ◽  
Southeast Alaska ◽  
Precommercial Thinning ◽  
Clear Cutting ◽  
Understory Biomass

In southeast Alaska, United States, multiple-use forest management objectives include both timber production and wildlife habitat. Following stand-replacing disturbances such as clear-cutting, Sitka spruce (Picea sitchensis (Bong.) Carrière) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) naturally regenerate and competitively dominate resources, excluding understory biomass and biodiversity. Thinning may mitigate the effects of canopy closure and permit understory development, but evidence of the effect on understories 8–10 years after thinning is lacking. We report results 4–5 and 8–10 years after thinning experiments on the Tongass National Forest to demonstrate the effects of precommercial thinning (thinned versus control), stand age (15–25, 25–35, and 35–50 years), and weather on understory dynamics and Sitka black-tailed deer (Odocoileus hemionus sitkensis Merriam, 1898) forage availability. Stand density negatively affected understory biomass, whereas temperature and precipitation positively interacted to increase biomass. Thinning had an enduring effect on understories, with biomass at least twice as great in thinned versus unthinned stands through year 10. We identified compositional differences from thinning as stand age class increased. Deer forage responded similarly to biomass, but thinning-induced differences faded with increased winter snowfall scenarios, especially in older stands. This study aids the understanding of stand overstory and understory development following silvicultural treatments in the coastal temperate rain forest of Alaska and suggests management implications and applications for balancing objectives throughout the forest type.

scholarly journals Porcupine Feeding Damage in Precommercially Thinned Conifer Stands of Central Southeast Alaska

1997 ◽  
Vol 12 (4) ◽  
pp. 115-121 ◽  
Author(s):  
Andris Eglitis ◽  
Paul E. Hennon
Keyword(s):  
Host Selection ◽  
Sitka Spruce ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Western Hemlock ◽  
Feeding Damage ◽  
Southeast Alaska ◽  
Erethizon Dorsatum ◽  
Young Growth

Abstract This study describes feeding damage by porcupines (Erethizon dorsatum) in precommercially thinned young growth stands of Sitka spruce (Picea sitchensis) and western hemlock (Tsuga heterophylla) on Mitkof Island in central southeast Alaska. We examined 641 trees from 54 sampling plots along transect lines in three 12 to 20 yr old stands. Porcupine feeding was monitored each spring and fall from 1985 to 1987. Four categories of feeding damage are described: complete girdling of the bole, partial girdling (bole scars), branch clipping, and "tasting wounds" (small basal bole scars). Sitka spruce, the primary crop tree in these thinned stands, sustained significantly higher damage (52% of trees affected) than western hemlock (26% of trees affected). Porcupine feeding was greater on taller than shorter Sitka spruce. Although only 8 of 59 trees initially girdled in 1985 were killed, many later sustained additional feeding damage. Following the 1987 season 3 yr after thinning, nearly 30% of the spruce and 14% of the western hemlock crop trees had been partially or completely girdled. Issues deserving future attention include the role of thinning in predisposing stands to porcupine damage, methods of population assessment, and mechanisms of host selection by porcupines. West. J. Appl. For. 12(4):115-121.

Dynamics of decline and mortality of Chamaecyparis nootkatensis in southeast Alaska

1990 ◽  
Vol 68 (3) ◽  
pp. 651-662 ◽  
Author(s):  
P. E. Hennon ◽  
E. M. Hansen ◽  
C. G. Shaw III
Keyword(s):  
Basal Area ◽  
Understory Vegetation ◽  
Aerial Photographs ◽  
Ecological Gradient ◽  
Southeast Alaska ◽  
Apparent Lack ◽  
Chamaecyparis Nootkatensis ◽  
Local Spread ◽  
Species Specific

Alaska-cedar, Chamaecyparis nootkatensis (D. Don) Spach, has been dying in undisturbed forests throughout southeast Alaska for the last 100 years. To determine if decline spreads, boundaries of mortality at seven sites with decline were mapped using aerial photographs taken in 1927, 1948, 1965, and 1976. Mortality was present at all seven sites in 1927. The boundaries of mortality have since expanded, but not by more than 100 m beyond the 1927 limit. In ground surveys, dead Alaska-cedar trees, classified according to their degree of deterioration, were recorded in 427 plots along 39 transects. Fifty-five taxa of understory vegetation were also recorded from 280 plots along these 21 transects; an ordination was produced from their distribution that represented a gradient from bogs to sites with better drainage. Most mortality was associated with bog and semibog sites. Alaska-cedar has a disproportionate level of mortality (65% of basal area dead) relative to other conifers. Local spread of cedar decline occurred along this gradient, as plots with more recently killed cedar trees had high average ordination scores (better drainage) and plots with cedars killed long ago had low average scores (boggy). Snags that probably date from the onset of extensive mortality were relatively common (at least 8% of all snags) on all 23 sites where intensive mortality was surveyed on the ground. As all sites with mortality that we investigated throughout southeast Alaska have these snags, decline does not appear to have spread to new sites since its onset. Although decline is relatively species specific and has patterns of local spread, the spread of mortality is along a specific, preexisting ecological gradient. These results, and the apparent lack of any site to site spread in the last 100 years, suggest that Alaska-cedar decline is not caused by some biotic agent.

Modeling the incidence and severity of hemlock dwarf mistletoe in 110-year-old wind-disturbed forests in Southeast Alaska

1998 ◽  
Vol 28 (10) ◽  
pp. 1501-1508 ◽  
Author(s):  
L M Trummer ◽  
P E Hennon ◽  
E M Hansen ◽  
P S Muir
Keyword(s):  
Basal Area ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Western Hemlock ◽  
Managed Forests ◽  
Coastal Forests ◽  
Dwarf Mistletoe ◽  
Infection Level ◽  
Southeast Alaska ◽  
Preliminary Validation

Amodel was developed to predict the severity of dwarf mistletoe (Arceuthobium tsugense (Rosendahl) G.N. Jones) in western hemlock trees (Tsuga heterophylla (Raf.) Sarg.) that developed within forests of Southeast Alaska that experienced near-catastrophic windthrow in the late 1800s. The model suggests that the degree of dwarf mistletoe severity on western hemlock trees was significantly and positively correlated with levels of dwarf mistletoe infection and basal area (m2/ha) in large and small residual trees that survived the wind disturbance. No significant relationships were found between severity level and any other factors, including site productivity, density of coexisting Sitka spruce (Picea sitchensis (Bong.) Carr.), or slope. The model demonstrates the overriding importance of infected residual trees to predict future severity of dwarf mistletoe; greater size and infection level of residual trees results in greater dwarf mistletoe levels on regenerating hemlock crop trees. The model, derived from 76 plots on Kuiu Island, was tested in 18 plots on Chichagof Island, providing a preliminary validation. Slower rates of dwarf mistletoe spread and intensification in forests of southeastern Alaska, as compared with similar coastal forests south of Alaska, provide an opportunity for managers to manipulate the parasite to desired levels in managed forests.

Managing for adaptive capacity: thinning improves food availability for wildlife and insect pollinators under climate change conditions

2013 ◽  
Vol 43 (5) ◽  
pp. 428-440 ◽  
Author(s):  
Andrew R. Neill ◽  
Klaus J. Puettmann
Keyword(s):  
Climate Change ◽  
Adaptive Capacity ◽  
Food Availability ◽  
Management Practices ◽  
Basal Area ◽  
Understory Vegetation ◽  
Wildlife Habitat ◽  
Ecosystem Functions ◽  
Fleshy Fruit ◽  
Species Groups

A trait-based approach was developed to assess impacts of management practices on the adaptive capacity of ecosystems using impacts of overstory density and thinning on understory vegetation components related to wildlife habitat. The relationship between overstory basal area and understory vegetation for species grouped by traits that reflect food availability for wildlife (i.e., the production of flowers, fleshy fruit, and palatable leaves) was characterized in thinned and unthinned stands at seven Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests in western Oregon 6 years following thinning. Lower overstory densities and thinnings were associated with a higher likelihood of selected ecosystem functions, specifically the provision of food for wildlife, as evident by higher cover of flowering, fleshy fruit and palatable leaf producing species. Within these functional groups, thinning increased cover of drought-, fire-, and heat-tolerant species, which suggests that these ecosystem functions are more likely to be maintained under climate change conditions. The responses of species groups appear to be driven by the sensitivity of species to resource availability and to physical disturbances associated with thinnings.

Stand dynamics of mixed red alder – conifer forests of southeast Alaska

2004 ◽  
Vol 34 (4) ◽  
pp. 969-980 ◽  
Author(s):  
Robert L Deal ◽  
Paul E Hennon ◽  
Ewa H Orlikowska ◽  
David V D'Amore
Keyword(s):  
Stand Structure ◽  
Large Diameter ◽  
Basal Area ◽  
Height Growth ◽  
Diameter Distribution ◽  
Height Distribution ◽  
Conifer Forests ◽  
Red Alder ◽  
Southeast Alaska ◽  
Dead Trees

Stand structure and dynamics were evaluated in mixed red alder (Alnus rubra Bong.) – conifer forests of southeast Alaska. We assessed stand development, tree density, total basal area, diameter distribution of live and dead trees, height distribution of live trees, and mean diameter of all and largest conifers in 40-year-old red alder – conifer stands that developed following logging. Forty-five plots were established in nine stands sampled across a com po si tional range of 0%–86% alder. Alder height growth was initially rapid then slowed considerably, whereas conifer height growth was initially slow then rapidly increased with conifers now being 4–9 m taller than associated alders. Most alder diameters were 20–30 cm and conifer diameters were more variable with numerous small (3–10 cm) and a few large (>25 cm) trees. Total stand basal area significantly decreased (p = 0.013) with increasing proportions of alder, but density of live and dead trees was not closely associated with alder composition. More than 60% of all dead trees died standing regardless of size or species. Overall, these mixed red alder – conifer stands provided more heterogeneous structures than pure conifer stands, with more even diameter distributions, multiple canopy layers, and similar numbers of large diameter conifers.

scholarly journals Effects of Pine and Hardwood Basal Areas After Uneven-Aged Silvicultural Treatments on Wildlife Habitat

1999 ◽  
Vol 23 (3) ◽  
pp. 151-157
Author(s):  
Darren A. Miller ◽  
Bruce D. Leopold ◽  
L. Mike Conner ◽  
Michael G. Shelton
Keyword(s):  
Habitat Structure ◽  
Southeastern United States ◽  
Basal Area ◽  
Wildlife Habitat ◽  
Total Biomass ◽  
Higher Plant ◽  
Wildlife Species ◽  
Silvicultural Treatments ◽  
Management Regime ◽  
Understory Biomass

Abstract Uneven-aged management (UEAM) is becoming increasingly popular in the southeastern United States. However, effects of UEAM on wildlife habitat have not been adequately documented. We examined response of habitat within stands of varying levels of pine and hardwood basal area under an uneven-aged management regime in southern Mississippi. Summer and winter trends in understory biomass were similar across treatments. Time since disturbance influenced plant productivity. Stands with lower basal areas tended to have higher browse production, denser and higher vertical habitat structure, more woody, vine, and fern biomass, greater total biomass, and higher plant species diversity and richness. Pine basal area had little influence on browse production relative to effects of hardwood basal area. Although stands with higher basal area had less biomass, a higher proportion of biomass was composed of preferred browse. We recommend that forest managers create stands of varying levels of pine and hardwood basal areas to provide for diverse needs of many wildlife species. South. J. Appl. For. 23(3):151-157.

Factors affecting distribution of wood, detritus, and sediment in headwater streams draining managed young-growth red alder – conifer forests in southeast Alaska

2006 ◽  
Vol 36 (3) ◽  
pp. 725-737 ◽  
Author(s):  
Takashi Gomi ◽  
Adelaide C Johnson ◽  
Robert L Deal ◽  
Paul E Hennon ◽  
Ewa H Orlikowska ◽  
...  
Keyword(s):  
Headwater Streams ◽  
Mass Movement ◽  
Timber Harvesting ◽  
Riparian Forests ◽  
Spatial And Temporal Variability ◽  
Large Wood ◽  
Short Channel ◽  
Red Alder ◽  
Southeast Alaska ◽  
Young Growth

Factors (riparian stand condition, management regimes, and channel properties) affecting distributions of wood, detritus (leaves and branches), and sediment were examined in headwater streams draining young-growth red alder (Alnus rubra Bong.) – conifer riparian forests (< 40 years old) in southeast Alaska. More riparian red alder were found along streams affected by both timber harvesting and mass movement than in streams affected by timber harvesting alone. Young-growth stands produced little large wood material (diameter ≥10 cm) and had little effect on altering the size distribution of functional large wood in channels, although more alder wood pieces were found in streams with greater numbers of riparian alder trees. Legacy wood pieces (>40 years old) remained in channels and provided sites for sediment and organic matter storage. Despite various alder–conifer mixtures and past harvesting effects, the abundance of large wood, fine wood, and detritus accumulations significantly decreased with increasing channel bank-full width ( 0.5–3.5 m) along relatively short channel distances (up to 700 m). Changes in wood, detritus, and sediment accumulations together with changes in riparian stand characteristics create spatial and temporal variability of in-channel conditions in headwater systems. A component of alder within young-growth riparian forests may benefit both wood production and biological recovery in disturbed headwater stream channels.

Modeling specific gravity and diameter inside bark of western hemlock and Sitka spruce growing in southeast Alaska

2021 ◽  
Author(s):  
Joseph Dahlen ◽  
David Auty ◽  
Eini C. Lowell
Keyword(s):  
Specific Gravity ◽  
Fixed Effects ◽  
Sitka Spruce ◽  
Western Hemlock ◽  
Fit Indices ◽  
Southeast Alaska ◽  
Important Species ◽  
Explanatory Variables ◽  
Cambial Age ◽  
Young Growth

Western hemlock and Sitka spruce are two commercially important species in Alaska with harvests beginning to focus on naturally regenerated young-growth. We developed within-tree models of ring specific gravity (SG) and diameter inside bark (DIB) for young-growth western hemlock and Sitka spruce. Eight even-aged stands (age < 75 years) in southeast Alaska were felled and disks collected from multiple height levels; 128 trees and 451 disks were collected for western hemlock, and 217 trees and 952 disks were collected for Sitka spruce. Radial strips were prepared and scanned using X-ray densitometry. We fitted non-linear mixed-effects models to the data, with cambial age, height within tree, and dominance class used as explanatory variables. The R2 values (fixed effects only) for the SG models were 0.48 and 0.42 for western hemlock and Sitka spruce, respectively. The corresponding fit indices for the DIB models were 0.86 and 0.85 percent for western hemlock and Sitka spruce, respectively. Tree maps depicting the within tree variation in SG showed more variability in Sitka spruce than in western hemlock. The wood and growth properties of young-growth trees in Alaska will continue to become more important as the U.S. Forest Service transitions away from harvesting old-growth trees.

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