scholarly journals Partial Retention of Legacy Trees Protect Mycorrhizal Inoculum Potential, Biodiversity, and Soil Resources While Promoting Natural Regeneration of Interior Douglas-Fir

2021 ◽  
Vol 3 ◽  
Author(s):  
Suzanne W. Simard ◽  
W. Jean Roach ◽  
Jacob Beauregard ◽  
Julia Burkart ◽  
Dominique Cook ◽  
...  
Keyword(s):  
Resource Availability ◽  
Forest Floor ◽  
Douglas Fir ◽  
Inoculum Potential ◽  
Soil Resources ◽  
Mycorrhizal Inoculum Potential ◽  
Tree Retention ◽  
Harvesting Intensity ◽  
Overstory Trees ◽  
Partial Retention

Clearcutting reduces proximity to seed sources and mycorrhizal inoculum potential for regenerating seedlings. Partial retention of legacy trees and protection of refuge plants, as well as preservation of the forest floor, can maintain mycorrhizal networks that colonize germinants and improve nutrient supply. However, little is known of overstory retention levels that best protect mycorrhizal inoculum while also providing sufficient light and soil resources for seedling establishment. To quantify the effect of tree retention on seedling regeneration, refuge plants, and resource availability, we compared five harvesting methods with increasing retention of overstory trees (clearcutting (0% retention), seed tree (10% retention), 30% patch retention, 60% patch retention, and 100% retention in uncut controls) in an interior Douglas-fir-dominated forest in British Columbia. Regeneration increased with proximity to legacy trees in partially cut forests, with increasing densities of interior Douglas-fir, western redcedar, grand fir, and western hemlock seedlings with overstory tree retention. Clearcutting reduced cover of ectomycorrhizal refuge plants (from 80 to 5%) while promoting arbuscular mycorrhizal plants the year after harvest. Richness of shrubs, herbs, and mosses declined with increasing harvesting intensity, but tree richness remained at control levels. The presence of legacy trees in all partially cut treatments mitigated these losses. Light availability declined with increasing overstory cover and proximity to leave trees, but it still exceeded 1,000 W m−2 in the clearcut, seed tree and 30% retention treatments. Increasing harvesting intensity reduced aboveground and belowground C stocks, particularly in live trees and the forest floor, although forest floor losses were also substantial where thinning took place in the 60% retention treatment. The loss of forest floor carbon, along with understory plant richness with intense harvesting was likely associated with a loss of ectomycorrhizal inoculum potential. This study suggests that dispersed retention of overstory trees where seed trees are spaced ~10–20 m apart, and aggregated retention where openings are <60 m (2 tree-lengths) in width, will result in an optimal balance of seed source proximity, inoculum potential, and resource availability where seedling regeneration, plant biodiversity, and carbon stocks are protected.

scholarly journals Profiles of C- and N-trace gas production in N-saturated forest soils

2005 ◽  
Vol 2 (4) ◽  
pp. 1127-1157 ◽  
Author(s):  
K. Butterbach-Bahl ◽  
U. Berger ◽  
N. Brüggemann ◽  
J. Duyzer
Keyword(s):  
Forest Soils ◽  
Forest Floor ◽  
Soil Depth ◽  
Douglas Fir ◽  
Anaerobic Incubation ◽  
N2o Production ◽  
Time Activity ◽  
Soil Layers ◽  
Clear Cut ◽  
First Time

Abstract. This study provides for the first time data on the stratification of NO and N2O production with soil depth under aerobic and anaerobic incubation conditions for different temperate forest sites in Germany (spruce, beech, clear-cut) and the Netherlands (Douglas fir). Results show that the NO and N2O production activity is highest in the forest floor and decreases exponentially with increasing soil depth. Under anaerobic incubation conditions NO and N2O production was in all soil layers up to 2-3 orders of magnitude higher then under aerobic incubation conditions. Furthermore, significant differences between sites could be demonstrated with respect to the magnitude or predominance of NO and N2O production. These were driven by stand properties (beech or spruce) or management (clear-cut versus control). With regard to CH4 the most striking result was the lack of CH4 uptake activity in soil samples taken from the Dutch Douglas fir site at Speulderbos, which is most likely a consequence of chronically high rates of atmospheric N deposition. In addition, we could also demonstrate that CH4 fluxes at the soil surface are obviously the result of simultaneously occurring uptake and production processes, since even under aerobic conditions a net production of CH4 in forest floor samples was found. The provided dataset will be very useful for the development and testing of process oriented models, since for the first time activity data stratified for several soil layers for N2O, NO, and CH4 production/oxidation activity for forest soils are provided.

scholarly journals Decoupling of a Douglas fir canopy: a look into the subcanopy with continuous vertical temperature profiles

2020 ◽  
Vol 17 (24) ◽  
pp. 6423-6439
Author(s):  
Bart Schilperoort ◽  
Miriam Coenders-Gerrits ◽  
César Jiménez Rodríguez ◽  
Christiaan van der Tol ◽  
Bas van de Wiel ◽  
...  
Keyword(s):  
Forest Floor ◽  
Thermal Stratification ◽  
Douglas Fir ◽  
Temperature Profiles ◽  
Distributed Temperature Sensing ◽  
Vertical Temperature ◽  
Vertical Exchange ◽  
Forest Sites ◽  
Flux Measurements ◽  
Atmosphere Interaction

Abstract. Complex ecosystems such as forests make accurately measuring atmospheric energy and matter fluxes difficult. One of the issues that can arise is that parts of the canopy and overlying atmosphere can be turbulently decoupled from each other, meaning that the vertical exchange of energy and matter is reduced or hampered. This complicates flux measurements performed above the canopy. Wind above the canopy will induce vertical exchange. However, stable thermal stratification, when lower parts of the canopy are colder, will hamper vertical exchange. To study the effect of thermal stratification on decoupling, we analyze high-resolution (0.3 m) vertical temperature profiles measured in a Douglas fir stand in the Netherlands using distributed temperature sensing (DTS). The forest has an open understory (0–20 m) and a dense overstory (20–34 m). The understory was often colder than the atmosphere above (80 % of the time during the night, >99 % during the day). Based on the aerodynamic Richardson number the canopy was regularly decoupled from the atmosphere (50 % of the time at night). In particular, decoupling could occur when both u*<0.4 m s−1 and the canopy was able to cool down through radiative cooling. With these conditions the understory could become strongly stably stratified at night. At higher values of the friction velocity the canopy was always well mixed. While the understory was nearly always stably stratified, convection just above the forest floor was common. However, this convection was limited in its vertical extent, not rising higher than 5 m at night and 15 m during the day. This points towards the understory layer acting as a kind of mechanical “blocking layer” between the forest floor and overstory. With the DTS temperature profiles we were able to study decoupling and stratification of the canopy in more detail and study processes which otherwise might be missed. These types of measurements can aid in describing the canopy–atmosphere interaction at forest sites and help detect and understand the general drivers of decoupling in forests.

scholarly journals Occurrence of arbuscular mycorrhizal fungi in soils of early stages of a secondary succession of Atlantic Forest in South Brazil

2006 ◽  
Vol 20 (3) ◽  
pp. 513-521 ◽  
Author(s):  
Sidney Luiz Stürmer ◽  
Osmar Klauberg Filho ◽  
Maike Hering de Queiroz ◽  
Margarida Matos de Mendonça
Keyword(s):  
Species Richness ◽  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Secondary Succession ◽  
Arbuscular Mycorrhizal ◽  
Plant Species Richness ◽  
Atlantic Rain Forest ◽  
Inoculum Potential ◽  
Mycorrhizal Inoculum Potential ◽  
Successional Stages

Arbuscular mycorrhizal fungi (AMF) species diversity and mycorrhizal inoculum potential were assessed in areas representative of stages of secondary succession in the Brazilian Atlantic Rain Forest. Within each stage - pioneer, 'capoeirinha' and 'capoeirão'- four transects were established and three soil samples were taken along each transect. The plant community was dominated by Pteridium aquilinium in the pioneer stage, while Dodonaea viscosa and P. aquilinium were co-dominants in the 'capoeirinha' stage. In capoeirão, Miconia cinnamomifolia was dominant followed by Euterpe edulis. Total spore number per 100 g soil was significantly larger in the 'capoeirinha' stage than in the other stages, although the number of viable spores was similar among stages. Acaulosporaceae and Glomeraceae were the predominant families accounting for 83% of the total spores recovered. Of the 18 spore morphotypes, 10 were allocated to known species, with Acaulospora sp. and Glomus sp. being the dominants recovered in all samples. Simpson's index of diversity and evenness for AMF species were not significantly different among the successional stages and AMF species richness was negatively correlated with plant species richness. Soil from 'Capoeirinha" showed the highest inoculum potential (37%). Dominance of the mycorrhizal community by few sporulators and the relationship between plant and fungal diversity are discussed.

Comparison of decomposition models using wood density of Douglas-fir logs

1985 ◽  
Vol 15 (6) ◽  
pp. 1092-1098 ◽  
Author(s):  
Joseph E. Means ◽  
Kermit Cromack Jr ◽  
Paul C. MacMillan
Keyword(s):  
Wood Density ◽  
Residence Time ◽  
Forest Floor ◽  
Exponential Model ◽  
Douglas Fir ◽  
Decay Class ◽  
Decomposition Models ◽  
Independent Variable ◽  
The Mean ◽  
Single Exponential

Logs of Pseudotsugamenziesii (Mirb.) Franco that had been on the ground for up to 313 years were grouped into five decay classes that ranged from 1, essentially undecayed, to 5, soft and incorporated into the forest floor but still identifiable. The mean residence times on the forest floor were 7, 17, 33, 82, and 219 years for decay classes 1 through 5, respectively. The single-exponential model of litter decomposition was fitted to the density of these logs. The summation-exponential model was constructed by summing single-exponential models fitted to lignin, cellulose, and the acid detergent soluble fraction. Both models gave virtually identical, statistically significant fits to the data. Wood density of these Douglas-fir logs decreased more slowly than that of most species other researchers have studied. The single-exponential model gave mineralization rates (k) of 0.0063 and 0.0070 year−1 when residence time and decay class age (mean residence time of the decay class), respectively, were used as the independent variable. Lignin decayed more slowly than cellulose or the fraction soluble in hot acid detergent, both of which decayed at rates that were not significantly different; thus, the summation-exponential model is recommended when these constituents are of interest.

scholarly journals Fate of Overstory Trees and Patterns of Regeneration 12 Years After Clearcutting with Reserve Trees in Southwest Washington

2002 ◽  
Vol 17 (2) ◽  
pp. 78-85 ◽  
Author(s):  
Karl R. Buermeyer ◽  
Constance A. Harrington
Keyword(s):  
Pacific Northwest ◽  
Douglas Fir ◽  
Seedling Density ◽  
Site Class ◽  
Seedling Size ◽  
Advance Regeneration ◽  
Dead Trees ◽  
The Status ◽  
Overstory Trees ◽  
Southwest Washington

Abstract Changes in management objectives for some forestlands in the Pacific Northwest have spurred interest in the creation of multistoried stands and the use of natural regeneration systems, but data on such systems are lacking. We assessed the status of the overstory trees and the regeneration 12 yr after a clearcut harvest with reserve trees in an even-aged, 145-yr-old Douglas-fir stand on a moderately productive site (site class 3) in southwest Washington. The 15 ha harvest unit was superimposed over two areas differentially thinned 15 and 34 yr before clearcutting. The clearcut harvest retained 18 trees/ha with a mean diameter of 63 cm. The reserved overstory trees had a 93% survival rate after 12 yr; most dead trees had been windthrown. Diameter growth for the reserved trees averaged 3.3 cm and was greatest during the most recent 3 yr period, which also had the highest growing-season precipitation. In a 1 ha mapped area, there were 5,854 seedlings/ha, and more than 99% of the regeneration was Douglas-fir. Most seedlings were less than 2 m tall. Seedling density was somewhat clumped (value of 2.1 for Pielou's index of nonrandomness), but 79% of randomly located 4.04 m2 (mil-acre) plots and 98% of 5 × 5 m grid cells had at least one conifer seedling. There was no obvious pattern of regeneration based on direction from the reserved trees, but both seedling density and seedling size within the drip lines of reserved tree crowns were less than in the rest of the area. The number of seedlings was similar on the two halves of the plot corresponding to the original thinning blocks, but seedling size and age differed. In the half of the study plot that had been twice lightly thinned, only 14% of the seedlings were >0.5 m tall; however, 41% of the seedlings were >0.5 m in the block that had been thinned more heavily. There was no difference between the thinning blocks in the ages of seedlings ≤0.5 m tall (mean age of 5 yr). This example of clearcutting with reserve trees resulted in reasonable survival of the overstory trees and adequate stocking but slow growth rates in the naturally regenerated Douglas-fir. Heavier thinning before harvest was associated with more advance regeneration, more shrub cover, and less windthrow of the reserved trees than in the more lightly thinned block. If an abundance of tree species other than Douglas-fir was desired on this site, interplanting would be required. West. J. Appl. For.17(2):78–85.

Vesicular–arbuscular mycorrhizal ecology of little bluestem across a prairie–forest gradient

1989 ◽  
Vol 67 (9) ◽  
pp. 2678-2685 ◽  
Author(s):  
Pamela K. Benjamin ◽  
Roger C. Anderson ◽  
Anthony E. Liberta
Keyword(s):  
Plant Cover ◽  
Fungal Species ◽  
Soil Samples ◽  
Forest Community ◽  
Inoculum Potential ◽  
Mycorrhizal Inoculum Potential ◽  
Little Bluestem ◽  
Vesicular Arbuscular ◽  
Closed Forest ◽  
Vam Colonization

Changes in little bluestem (Schizachyrium scoparium) plant cover and vesicular–arbuscular mycorrhizae (VAM) root colonization, VAM spore density, and mycorrhizal inoculum potential were examined across a gradient from open sand prairie to closed oak–hickory forest in central Illinois. Soil samples were collected randomly and from the rhizosphere of little bluestem. Significant negative rank correlations were found between tree basal area and percent aerial cover of little bluestem, VAM colonization of little bluestem roots, mycorrhizal inoculum potential, and VAM spore abundance. However, spore abundances for randomly collected and rhizosphere soil samples, VAM colonization, and mycorrhizal inoculum potential had significant positive rank correlations with little bluestem cover. Highest spore densities were associated with the open sand prairie dominated end of the gradient, with lower spore numbers being found within the closed forest. Rhizosphere and randomly collected soil samples had a decrease in VAM fungal species richness as the vegetation types approached that of a closed forest community; however, dominant VAM fungal species were present throughout the gradient. Observed relationships between colonization, mycorrhizal inoculum potential, spore abundances, and little bluestem cover suggest interdependencies between host plant and associated mycobionts and (or) similar responses to environmental factors.

Biomass and nutrient content of Douglas-fir logs and other detrital pools in an old-growth forest, Oregon, U.S.A.

1992 ◽  
Vol 22 (10) ◽  
pp. 1536-1546 ◽  
Author(s):  
Joseph E. Means ◽  
Paul C. MacMillan ◽  
Kermit Cromack Jr.
Keyword(s):  
Forest Floor ◽  
Soluble Fraction ◽  
Close Association ◽  
C:N Ratio ◽  
Mineral Soil ◽  
Nutrient Content ◽  
Douglas Fir ◽  
Area Index ◽  
Old Growth Forest ◽  
N Release

Logs, forest floor, and mineral soil were sampled and measured, and snags were measured, in a 450-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand on the H.J. Andrews Experimental Forest, Oregon. Logs, some still identifiable after 300 years on the forest floor, contained large amounts of organic matter (222 Mg/ha), C (100 Mg/ha), water (559–10 700 L/log), N (183 kg/ha), and Ca (141 kg/ha), and smaller amounts of P (5.5 kg/ha), K (22 kg/ha), Mg (14 kg/ha), and Na (3.7 kg/ha). Logs and snags covered about 17% of the forest floor and had an all-sided area index of 0.69 m2/m2. Through mineralization, C, N, and K were lost through time; Ca and Mg increased; and P and Na increased then decreased, showing no net change. Also through mineralization, cellulose and hot acid detergent soluble fraction decreased more rapidly than lignin. Lignin was apparently not lost until the later stages of decay, when N was also lost in significant amounts. This parallels the shift from initial dominance by white rots that degraded cellulose and lignin to later dominance by brown rots that preferentially degraded cellulose. Lignin and cellulose were eventually lost at more similar rates in later decay stages. This may have been due in part to a close association between the remaining cellulose and lignin in later decay stages. Lignin was a better predictor of the onset of N release than was the C:N ratio.

Effects of forest litter on mycorrhiza development and growth of Douglas-fir and western red cedar seedlings

1983 ◽  
Vol 13 (4) ◽  
pp. 666-671 ◽  
Author(s):  
Jennifer L. Parke ◽  
R. G. Llnderman ◽  
J. M. Trappe
Keyword(s):  
Organic Matter ◽  
Mycorrhizal Fungi ◽  
Mycorrhizal Fungus ◽  
Forest Litter ◽  
Douglas Fir ◽  
Growth Enhancement ◽  
Inoculum Potential ◽  
Red Cedar ◽  
Western Red Cedar ◽  
Slash Burning

Preparation of forest regeneration sites prior to conifer planting often includes slash burning or physical removal of soil organic matter. Experiments were conducted to determine if organic matter contributes to the mycorrhizal fungus inoculum potential in forest soils and to compare the growth of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and western red cedar (Thujaplicata J. Donn ex D. Donn) seedlings with and without litter. Litter and humus were found to include inoculum of both vesicular–arbuscular (VA) and ectomycorrhizal fungi. Litter amendment usually enhanced growth of host seedlings, but growth enhancement could not be fully attributed to addition of mycorrhizal inoculum or nutrients provided by litter. These findings suggested that other biological factors stimulated the growth of conifer seedlings and (or) activity of mycorrhizal fungi.

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