The effect of soil disturbance on growth and ectomycorrhizae of Douglas-fir and western hemlock seedlings: a greenhouse bioassay

1982 ◽  
Vol 12 (2) ◽  
pp. 343-353 ◽  
Author(s):  
M. Meyer Schoenberger ◽  
D. A. Perry
Keyword(s):  
Soil Disturbance ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Root Tips ◽  
Old Growth ◽  
Clear Cut ◽  
Old Growth Forest ◽  
Litter Leachate ◽  
Oregon Cascades ◽  
Tip Formation

In a greenhouse bioassay of soils from the central Oregon Cascades, Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings had the most total and ectomycorrhizal root tips when grown in soil from an unburned clear-cut and the least when grown in soil from (i) a 20-year-old plantation that had been clear-cut and burned in the late 1950's and (ii) one old-growth forest. Tip formation was intermediate in soil from a second old-growth forest, a recently burned clear-cut, and a 40-year-old natural burn. Root weights followed the same trend, but top weights did not differ among the various soils. Ectomycorrhizal and total root tips of western hemlock (Tsugaheterophylla (Raf.) Sarg.) were lowest in soils from the plantation and recently burned clear-cut. Unlike Douglas-fir, western hemlock's tip production was not greater in the unburned clear-cut than in the old-growth forest soils. In this species, both top and root weights varied according to soil, with the largest seedlings produced in soil from the unburned clear-cut. With both species, there was a significant interaction between ectomycorrhizal type and soil type. Cenococcumgeophilum Fr. predominated on western hemlock and was reduced in soils from the burned clear-cut and plantation. In comparison with the mean for all soils, ectomycorrhizal types that predominated on Douglas-fir were enhanced in the unburned clear-cut soil and reduced in one old-growth soil, an effect apparently related to litter leachate.

Canopy disturbances over the five-century lifetime of an old-growth Douglas-fir stand in the Pacific Northwest

2002 ◽  
Vol 32 (6) ◽  
pp. 1057-1070 ◽  
Author(s):  
Linda E Winter ◽  
Linda B Brubaker ◽  
Jerry F Franklin ◽  
Eric A Miller ◽  
Donald Q DeWitt
Keyword(s):  
Pacific Northwest ◽  
Variable Density ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Old Growth ◽  
The Pacific ◽  
History Of ◽  
Horizontal Heterogeneity ◽  
Restoration Strategies

The history of canopy disturbances over the lifetime of an old-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stand in the western Cascade Range of southern Washington was reconstructed using tree-ring records of cross-dated samples from a 3.3-ha mapped plot. The reconstruction detected pulses in which many western hemlock (Tsuga heterophylla (Raf.) Sarg.) synchronously experienced abrupt and sustained increases in ringwidth, i.e., "growth-increases", and focused on medium-sized or larger ([Formula: see text]0.8 ha) events. The results show that the stand experienced at least three canopy disturbances that each thinned, but did not clear, the canopy over areas [Formula: see text]0.8 ha, occurring approximately in the late 1500s, the 1760s, and the 1930s. None of these promoted regeneration of the shade-intolerant Douglas-fir, all of which established 1500–1521. The disturbances may have promoted regeneration of western hemlock, but their strongest effect on tree dynamics was to elicit western hemlock growth-increases. Canopy disturbances are known to create patchiness, or horizontal heterogeneity, an important characteristic of old-growth forests. This reconstructed history provides one model for restoration strategies to create horizontal heterogeneity in young Douglas-fir stands, for example, by suggesting sizes of areas to thin in variable-density thinnings.

Impact of clearcutting and slash burning on ectomycorrhizal associations of Douglas-fir seedlings

1984 ◽  
Vol 14 (1) ◽  
pp. 94-100 ◽  
Author(s):  
David P. Pilz ◽  
David A. Perry
Keyword(s):  
Douglas Fir ◽  
Root Tip ◽  
Root Tips ◽  
Clear Cut ◽  
Clear Cutting ◽  
Ectomycorrhizal Types ◽  
Different Types ◽  
Undisturbed Forest ◽  
Soil Origin ◽  
Slash Burning

The effect of clear-cutting, with and without slash burning, on ectomycorrhizal formation of Douglas-fir seedlings (Pseudotsugamenziesii (Mirb.) Franco var. menziesii) was studied in field and greenhouse bioassays. Twelve ectomycorrhizal types were found in three western Cascade Mountain sites on seedlings planted in soils exchanged among burned and unburned portions of clear-cuts and undisturbed forest. Rhizopogon sp. and an unidentified brown type consistently formed at least two-thirds of the ectomycorrhizal root tips. Regardless of soil origin, more ectomycorrhizae formed in clear-cuts than in undisturbed forest (primarily due to more brown mycorrhizae). Soil origin did not affect total numbers of ectomycorrhizae; however, more different types formed in undisturbed forest soils than in clear-cut soils, irrespective of aboveground environment. More nonmycorrhizal tips occurred in clear-cut soils. Seedlings grown in the same soils formed the same proportions of Rhizopogon and brown types in field and greenhouse, but not the same proportions of less common ectomycorrhizal types. Soil pasteurization increased root-tip numbers. Inoculated soils (1 part nonpasteurized: 9 parts pasteurized) produced as many ectomycorrhizae as nonpasteurized field soils and generally fewer tips than pasteurized soils. Formation of major (but not minor) ectomycorrhizal types on all sites was influenced more by aboveground changes that accompany clear-cutting and site preparation than by alterations in soil chemistry or biology.

scholarly journals Vertical gradients in photosynthetic light response within an old-growth Douglas-fir and western hemlock canopy

2000 ◽  
Vol 20 (7) ◽  
pp. 447-456 ◽  
Author(s):  
J. D. Lewis ◽  
R. B. McKane ◽  
D. T. Tingey ◽  
P. A. Beedlow
Keyword(s):  
Light Response ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Old Growth ◽  
Vertical Gradients

Patterns of log decay in old-growth Douglas-fir forests

1987 ◽  
Vol 17 (12) ◽  
pp. 1585-1595 ◽  
Author(s):  
Phillip Sollins ◽  
Steven P. Cline ◽  
Thomas Verhoeven ◽  
Donald Sachs ◽  
Gody Spycher
Keyword(s):  
C:N Ratio ◽  
Dry Weight ◽  
Douglas Fir ◽  
Time Span ◽  
Western Hemlock ◽  
Tissue Type ◽  
Old Growth ◽  
Total N ◽  
Red Cedar ◽  
Western Red Cedar

Fallen boles (logs) of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), western hemlock (Tsugaheterophylla (Raf.) Sarg.), and western red cedar (Thujaplicata Donn) in old-growth stands of the Cascade Range of western Oregon and Washington were compared with regard to their physical structure, chemistry, and levels of microbial activity. Western hemlock and western red cedar logs disappeared faster than Douglas-fir logs, although decay rate constants based on density change alone were 0.010/year for Douglas-fir, 0.016/year for western hemlock, and 0.009/year for western red cedar. We were unable to locate hemlock or red cedar logs older than 100 years on the ground, but found Douglas-fir logs that had persisted up to nearly 200 years. Wood density decreased to about 0.15 g/cm3 after 60–80 years on the ground, depending on species, then remained nearly constant. Moisture content of logs increased during the first 80 years on the ground, then remained roughly constant at about 250% (dry-weight basis) in summer and at 350% in winter. After logs had lain on the ground for about 80 years, amounts of N, P, and Mg per unit volume exceeded the amount present initially. Amounts of Ca, K, and Na remained fairly constant throughout the 200-year time span that was studied (100-year time span for Na). N:P ratios converged toward 20, irrespective of tree species or wood tissue type. C:N ratios dropped to about 100 in the most decayed logs; net N was mineralized during anaerobic incubation of most samples with a C:N ratio below 250. The ratio of mineralized N to total N increased with advancing decay. Asymbiotic bacteria in fallen logs fixed about 1 kg N ha−1 year−1, a substantial amount relative to system N input from precipitation and dry deposition (2–3 kg ha−1 year−1).

scholarly journals Secondary disturbance following a deposit of volcanic tephra: A 30 year record from old-growth forest understory

2021 ◽  
Author(s):  
Donald B Zobel ◽  
Joseph A. Antos ◽  
Dylan Grey Fischer
Keyword(s):  
Vegetation Change ◽  
Forest Disturbance ◽  
Canopy Cover ◽  
Soil Disturbance ◽  
Tree Canopy ◽  
Forest Understory ◽  
Old Growth ◽  
Old Growth Forest ◽  
Volcanic Ejecta ◽  
Woody Litter

Forest disturbance is usually described by effects on trees, and small disturbances to forest understory are seldom studied. Nevertheless, effective analyses of succession need to consider both stand-replacing and subsequent “secondary” disturbances in both canopy and understory. We estimated characteristics of 13 types of secondary disturbance in old-growth forest understory, and of canopy cover, after the 1980 tephra (aerially transported volcanic ejecta) deposition from Mount St. Helens, Washington. We sampled 100 1-m2 plots at each of four sites for vegetation change and types of disturbance at ten times from 1980-2010; we sampled tree canopy above each plot in 1980 and 2016. The number of canopy gaps increased 23 % and mean gap dimension 68 % during 36 years, mostly from loss of Abies amabilis. Secondary disturbance in understory affected 1.4 % of stand area per year. The areas affected by soil disturbance and effects of woody litter were similar. Erosion, greater in deep than in shallow tephra, peaked in 1981, whereas most litter-caused disturbances increased after 2000. Less frequent litter-based disturbances covered greater area. Our results differ from conclusions about non-volcanic understory disturbances. Secondary disturbances are variable, need more study, and are likely to affect many other systems.

scholarly journals Bryophyte Conservation in Managed Boreal Landscapes: Fourteen-Year Impacts of Partial Cuts on Epixylic Bryophytes

2021 ◽  
Vol 4 ◽  
Author(s):  
Jeffrey Opoku-Nyame ◽  
Alain Leduc ◽  
Nicole J. Fenton
Keyword(s):  
Species Composition ◽  
Coarse Woody Debris ◽  
Black Spruce ◽  
Woody Debris ◽  
Permanent Plots ◽  
Old Growth ◽  
Clear Cut ◽  
Old Growth Forest ◽  
Old Growth Forests ◽  
Over Time

Clear cut harvest simplifies and eliminates old growth forest structure, negatively impacting biodiversity. Partial cut harvest has been hypothesized (1) to have less impact on biodiversity than clear cut harvest, and (2) to encourage old growth forest structures. Long-term studies are required to test this hypothesis as most studies are conducted soon after harvest. Using epixylic bryophytes as indicators, this study addresses this knowledge gap. Fourteen years after harvest, we examined changes in epixylic bryophyte community composition richness and traits, and their microhabitats (coarse woody debris characteristics and microclimate) along an unharvested, partial cuts and clear cuts harvest treatment in 30 permanent plots established in the boreal black spruce (Picea mariana) forests of northwestern Quebec, Canada. Our results were compared to those of an initial post-harvest study (year 5) and to a chronosequence of old growth forests to examine species changes over time and the similarity of bryophyte communities in partial cut and old growth forests. Coarse woody debris (CWD) volume by decay class varied among harvest treatments with partial cuts and clear cuts recording lower volumes of early decay CWD. The epixylic community was richer in partial cuts than in mature unharvested forests and clear cuts. In addition, species richness and overall abundance doubled in partial and clear cuts between years 5 and 14. Species composition also differed among treatments between years 5 and 14. Furthermore, conditions in partial cut stands supported small, drought sensitive, and old growth confined species that are threatened by conditions in clear cut stands. Lastly, over time, species composition in partial cuts became more similar to old growth forests. Partial cuts reduced harvest impacts by continuing to provide favorable microhabitat conditions that support epixylic bryophytes. Also, partial cut harvest has the potential to encourage old growth species assemblages, which has been a major concern for biodiversity conservation in managed forest landscapes. Our findings support the promotion of partial cut harvest as an effective strategy to achieve species and habitat conservation goals.

Water stress and survival of three species of conifer seedlings planted on a high elevation south-facing clear-cut

1987 ◽  
Vol 17 (9) ◽  
pp. 1115-1123 ◽  
Author(s):  
N. J. Livingston ◽  
T. A. Black
Keyword(s):  
Survival Rates ◽  
High Elevation ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Silver Fir ◽  
High Survival ◽  
High Survival Rate ◽  
Poor Survival ◽  
Tolerance Mechanisms ◽  
Clear Cut

Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), western hemlock (Tsugaheterophylla (Raf.) Sarg.), and Pacific silver fir (Abiesamabilis (Dougl.) Forbes) container-grown 1-0 seedlings were spring planted on a south-facing high elevation clear-cut located on Mount Arrowsmith, Vancouver Island, British Columbia. Treatments, which included inclining seedlings to the southwest, provision of shade cards, irrigation, and irrigation and shade cards combined, were applied to determine whether modification of seedling microclimate would increase survival. Highest survival rates, regardless of treatment, were shown by Douglas-fir. By April 1984, 72 and 82% of untreated Douglas-fir seedlings planted in 1981 and 1982, respectively, survived, whereas survival of treated seedlings ranged from 81 to 95%. The high survival rate in Douglas-fir appeared to be due to their high drought tolerance. The osmotic potential of unirrigated Douglas-fir seedlings declined by over 1.1 MPa during the course of the 1982 growing season in response to decreasing soil water potentials and consequently turgor was maintained in the foliage. Transpiration rates of these seedlings were never less than 50% of those that were irrigated. Western hemlock and Pacific silver fir seedlings exhibited very poor survival, possibly owing to the lack of stress avoidance and tolerance mechanisms. Survival rates of the two species were increased by shade cards and irrigation but never exceeded 64%.

Leaf area index of an old-growth Douglas-fir forest estimated from direct structural measurements in the canopy

2000 ◽  
Vol 30 (12) ◽  
pp. 1922-1930 ◽  
Author(s):  
Sean C Thomas ◽  
William E Winner
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Tsuga Heterophylla ◽  
Douglas Fir ◽  
Understory Vegetation ◽  
Western Hemlock ◽  
Old Growth ◽  
Area Index ◽  
Contact Frequency ◽  
Canopy Access

Leaf area index (LAI) in old-growth Douglas-fir (Pseudotsuga menziesii var menziesii (Mirb.) Franco) forests exceeds that of any other forest ecosystem by some estimates; however, LAI determinations in coniferous forests have generally been indirect, involving extrapolations of patterns observed in younger stands. Aided by a 75-m construction crane for canopy access, we used a vertical line-intercept method to estimate LAI for a [Formula: see text]450-year-old Douglas-fir - western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest in southwestern Washington state. LAI was calculated as the product of foliage contact frequency and an "extinction coefficient" accounting for foliage angular distribution, geometry, and the ratio of "interceptable" to total leaf area. LAI estimates were 9.3 ± 2.1 (estimate ± 95% confidence interval), 8.5 ± 2.2, and 8.2 ± 1.8 in 1997, 1998, and 1999, respectively, or 8.6 ± 1.1 pooled across years. Understory vegetation, including foliage of woody stems <5 cm diameter, represented 20% of this total. Sample points in which Douglas-fir was dominant had a higher total LAI than points dominated by western hemlock, including a higher LAI of understory vegetation. Our results do not support the contention that old-growth Douglas-fir - western hemlock forests maintain an appreciably higher LAI than do other forest ecosystems. Moreover, LAI in very old stands may decline as western hemlock replaces Douglas-fir through the course of succession.

Coarse woody debris and soil respiration in a clearcut on the Olympic Peninsula, Washington, U.S.A.

1996 ◽  
Vol 26 (8) ◽  
pp. 1337-1345 ◽  
Author(s):  
James L. Marra ◽  
Robert L. Edmonds
Keyword(s):  
Soil Respiration ◽  
Respiration Rate ◽  
Coarse Woody Debris ◽  
Woody Debris ◽  
Douglas Fir ◽  
Western Hemlock ◽  
Olympic Peninsula ◽  
Old Growth ◽  
Growth Site ◽  
Respiration Rates

Coarse woody debris (CWD) and soil respiration rates were measured using soda lime traps on a clearcut site in the Hoh River Valley on the west side of the Olympic Peninsula, Washington. The influence of species of CWD (western hemlock (Tsugaheterophylla (Raf.) Sarg.) and Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco)), decay class, and log diameter on respiration rates was determined. CWD and soil respiration were measured every 4 weeks from October 1991 to November 1992 along with CWD and soil temperature and moisture contents. Western hemlock logs respired at a significantly higher rate (4.05 g CO2•m−2•day−1) than Douglas-fir logs (2.94 g CO2•m−2•day−1). There were no significant differences between respiration rates for decay classes 1–2, 3, and 5 logs (4.47, 3.69, and 4.28 g CO2•m−2•day−1, respectively), and there was no strong relationship between CWD respiration rate and log diameter. The highest average respiration rate was from the soil in the clearcut (5.22 g CO2•m−2•day−1). Averaged for the year, log and soil respiration rates in the clearcut site were similar to those in an adjacent old-growth forested site. However, seasonal fluctuations were greater on the clearcut site. Higher summer respiration rates and lower winter rates observed on the clearcut relative to the old-growth site appeared to be driven more by temperature than by moisture. Clear-cutting also resulted in higher summer CWD and soil temperatures and lower winter temperatures compared with the old-growth site.

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