Substrates mediate responses of forest bryophytes to a gradient in overstory retention

2014 ◽  
Vol 44 (8) ◽  
pp. 855-866 ◽  
Author(s):  
Charles B. Halpern ◽  
Martin Dovčiak ◽  
Lauren S. Urgenson ◽  
Shelley A. Evans
Keyword(s):  
Forest Management ◽  
Forest Floor ◽  
Environmental Changes ◽  
Basal Area ◽  
Species Evenness ◽  
Substrate Quality ◽  
Area 7 ◽  
Dispersed Retention ◽  
Canopy Removal

Forest bryophytes are sensitive to the disturbances and environmental changes associated with forest management. We asked whether the substrates on which bryophytes grow mediate responses to exposure following canopy removal. We measured bryophyte cover and richness in 0.1 m2 quadrats on the forest floor, decayed logs, and tree bases along a gradient of dispersed overstory retention (100%, 40%, and 15% of initial basal area) 7 to 8 years after harvest of mature Pseudotsuga forests. Cover, local richness, and, to a lesser degree, species evenness declined steeply across the retention gradient on decayed logs and tree bases but not on the forest floor. Liverworts were more sensitive than mosses, particularly on decayed logs and on the southwestern aspects of trees (>97% declines in cover under 15% retention). Richness and evenness at the treatment scale also declined sharply on decayed logs and on the southwestern aspects of trees but changed little or increased under 40% retention on the forest floor. Our results indicate that even moderate levels of dispersed retention cannot sustain the abundance and overall diversity of wood-associated bryophytes in these forests. During regeneration harvests, conservation of these species may require retention of intact forest aggregates in which substrate quality and microclimatic stability can be maintained.

scholarly journals Quantifying the missing link between forest albedo and productivity in the boreal zone

2016 ◽  
Vol 13 (21) ◽  
pp. 6015-6030 ◽  
Author(s):  
Aarne Hovi ◽  
Jingjing Liang ◽  
Lauri Korhonen ◽  
Hideki Kobayashi ◽  
Miina Rautiainen
Keyword(s):  
Forest Management ◽  
Forest Floor ◽  
Basal Area ◽  
Shortwave Radiation ◽  
Coniferous Forests ◽  
Radiative Transfer Model ◽  
Radiation Balance ◽  
Transfer Model ◽  
Intensively Managed ◽  
The Relationship

Abstract. Albedo and fraction of absorbed photosynthetically active radiation (FAPAR) determine the shortwave radiation balance and productivity of forests. Currently, the physical link between forest albedo and productivity is poorly understood, yet it is crucial for designing optimal forest management strategies for mitigating climate change. We investigated the relationships between boreal forest structure, albedo and FAPAR using a radiative transfer model called Forest Reflectance and Transmittance model FRT and extensive forest inventory data sets ranging from southern boreal forests to the northern tree line in Finland and Alaska (N  =  1086 plots). The forests in the study areas vary widely in structure, species composition, and human interference, from intensively managed in Finland to natural growth in Alaska. We show that FAPAR of tree canopies (FAPARCAN) and albedo are tightly linked in boreal coniferous forests, but the relationship is weaker if the forest has broadleaved admixture, or if canopies have low leaf area and the composition of forest floor varies. Furthermore, the functional shape of the relationship between albedo and FAPARCAN depends on the angular distribution of incoming solar irradiance. We also show that forest floor can contribute to over 50 % of albedo or total ecosystem FAPAR. Based on our simulations, forest albedos can vary notably across the biome. Because of larger proportions of broadleaved trees, the studied plots in Alaska had higher albedo (0.141–0.184) than those in Finland (0.136–0.171) even though the albedo of pure coniferous forests was lower in Alaska. Our results reveal that variation in solar angle will need to be accounted for when evaluating climate effects of forest management in different latitudes. Furthermore, increasing the proportion of broadleaved trees in coniferous forests is the most important means of maximizing albedo without compromising productivity: based on our findings the potential of controlling forest density (i.e., basal area) to increase albedo may be limited compared to the effect of favoring broadleaved species.

Persistence of ground-layer bryophytes in a structural retention experiment: initial effects of level and pattern of overstory retention

2006 ◽  
Vol 36 (11) ◽  
pp. 3039-3052 ◽  
Author(s):  
Martin Dovčiak ◽  
Charles B Halpern ◽  
James F Saracco ◽  
Shelley A Evans ◽  
Denise A Liguori
Keyword(s):  
Spatial Patterns ◽  
Edge Effects ◽  
Forest Floor ◽  
Basal Area ◽  
First Year ◽  
Clear Cut ◽  
Dispersed Retention ◽  
Western Washington ◽  
Structural Retention ◽  
Species Frequencies

We examined first-year responses of forest-floor bryophytes to structural retention harvests at four locations in western Washington. Treatments represented a range of retention levels (100%, 75%, 40%, and 15% of original basal area) and spatial patterns (dispersed vs. aggregated in 1 ha patches). Declines in bryophyte cover and species' frequencies were comparably large at 40% and 15% retention. Retention pattern had little effect on the magnitude of decline, although declines in richness tended to be greater in aggregated treatments. Changes in cover were small within forest aggregates (comparable to controls). However, richness declined relative to controls within aggregates at 15% retention; rarer taxa in these exposed patches may be susceptible to edge effects. Declines in species' frequencies and richness were consistently greater in "clear-cut" areas of aggregated treatments than in dispersed retention; liverworts were particularly sensitive to harvest. In cut areas, bryophytes responded positively to cover of understory vegetation and negatively to logging slash. The positive correlation of richness (but not cover) to tree basal area may reflect the contribution of tree boles to persistence of rarer corticolous species. Our results suggest that conservation of bryophytes in forests managed with structural retention will require large retention patches and dispersed trees at levels considerably higher than current retention standards.

Functional association between apogeotropic aerial roots, mycorrhizas and paper-barked stems in a lowland tropical rainforest in North Queensland

1996 ◽  
Vol 12 (6) ◽  
pp. 763-777 ◽  
Author(s):  
Paul Reddell ◽  
Michael S. Hopkins ◽  
Andrew W. Graham
Keyword(s):  
Mycorrhizal Fungi ◽  
Forest Floor ◽  
Tropical Rainforest ◽  
Strong Association ◽  
Basal Area ◽  
Arbuscular Mycorrhizal ◽  
Coastal Site ◽  
Aerial Roots ◽  
Consistent Feature ◽  
Eleven Species

ABSTRACTThe root and trunk characteristics of species in a complex, lowland, evergreen, tropical rainforest at a seasonally inundated, coastal site on siliceous sands were examined. Roots in the soil were predominantly colonized by arbuscular mycorrhizal fungi although ectomycorrhizas were found on four species which contributed almost 25% of total basal area. Surface root mats were not a characteristic of the study site. In contrast, the ability to produce apogeotropic (upwardly growing) aerial roots which grew on and within the bark on trunks and branches was a consistent feature of the dominant species of trees in this forest. Eleven species representing eight families and constituting more than 85% of the basal area at the site produced these roots. Most trunks with DBH greater than 20 cm supported apogeotropic aerial roots produced by a range of species including themselves. Apogeotropic roots were most frequently found on the basal 0.5 m of trunks; however, they did occur up to 5 m above the forest floor. Apogeotropic aerial roots originated both from epicormic buds under the bark and from soil, and they were frequently colonized by arbuscular mycorrhizal and ectomycorrhizal fungi. There was a strong association between the ability to support these upwardly growing roots and the occurrence of laminated papery and flaky bark. We postulate that production of apogeotropic roots may provide a mechanism for nutrient uptake and root respiration during periods of inundation, for intercepting nutrients in stemflow and/or for extracting nutrients from bark.

scholarly journals Multiple environmental changes drive forest floor vegetation in a temperate mountain forest

2017 ◽  
Vol 7 (7) ◽  
pp. 2155-2168 ◽  
Author(s):  
Norbert Helm ◽  
Franz Essl ◽  
Michael Mirtl ◽  
Thomas Dirnböck
Keyword(s):  
Forest Floor ◽  
Environmental Changes ◽  
Mountain Forest ◽  
Forest Floor Vegetation

Twelve-year responses of planted and naturally regenerating conifers to variable-retention harvest in the Pacific Northwest, USA

2013 ◽  
Vol 43 (1) ◽  
pp. 46-55 ◽  
Author(s):  
Lauren S. Urgenson ◽  
Charles B. Halpern ◽  
Paul D. Anderson
Keyword(s):  
Pacific Northwest ◽  
Natural Regeneration ◽  
Regional Scale ◽  
Basal Area ◽  
Pinus Monticola ◽  
Variable Retention ◽  
The Pacific ◽  
Dispersed Retention ◽  
Variable Retention Harvest ◽  
Scale Experiment

We studied patterns of conifer regeneration over 12 years as part of a regional-scale experiment in variable-retention harvest in the Pacific Northwest, the DEMO Study. We compared survival and height growth of planted conifers and density and seral composition of natural regeneration among treatments with differing retention levels (15% versus 40%) and patterns (dispersed versus aggregated) replicated across a range of latitudes and forest zones. We also assessed plot-scale relationships of natural regeneration with overstory density and basal area, competing vegetation, and slash accumulations. Early (1- to 2-year) survival of planted seedlings was greater in dispersed treatments (Pinus monticola Douglas ex D. Don, Abies spp.) or unaffected by retention level or pattern (Pseudotsuga menziesii (Mirb.) Franco). Later (5- to 12-year) survival did not differ (all species), but growth was distinctly reduced in dispersed treatments and (or) at higher levels of retention. Density of natural regeneration was 1.5–2.5 times greater in dispersed treatments than in the cleared areas of aggregated treatments. Low-level dispersed retention promoted Pseudotsuga, the early-seral dominant, presumably by enhancing seed rain within a relatively high-light environment. Dispersed retention favored late-seral conifers. The ability to manipulate retention pattern and level to influence regeneration density and composition provides managers with flexibility in developing structurally complex and compositionally diverse forests.

scholarly journals Species Mixing Regulation with Respect to Forest Ecosystem Service Provision

Forests ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 632 ◽  
Author(s):  
Fabian Schwaiger ◽  
Werner Poschenrieder ◽  
Peter Biber ◽  
Hans Pretzsch
Keyword(s):  
Forest Management ◽  
Groundwater Recharge ◽  
Ecosystem Service ◽  
Service Provision ◽  
Quantitative Methods ◽  
Basal Area ◽  
Stand Density ◽  
European Beech ◽  
Stand Age ◽  
Mixed Stands

The control and maintenance of species composition of mixed stands is a highly relevant objective of forest management in order to provide multifunctionality and climatic resilience. In contrast to this requirement there is, however, an evident lack of quantitative methods for mixture regulation. In this context, we propose an approach for the regulation of mixture proportions that has been implemented in a forest management model. The approach considers species-specific growth characteristics and takes into account the mixing effect on stand density. We present five exemplary simulations that apply the regulation. Each simulation maintains one of five desired species compositions. In these simulations, we consider the species European beech and Norway spruce under good site conditions, thus representing the most prominent mixed stands in Central Europe. Based on this model experiment, we analyze the potential benefit of controlled mixing regulation for achieving desired levels and combinations of ecosystem service provision, in particular productivity, diversity, and groundwater recharge. We found that a constant 50% basal area share of beech (equivalent growing space share of 80% to 70% depending on stand age) provided the most balanced supply of ecosystem services. Prominently, groundwater recharge considerably decreased when beech basal area shares were held below 50%. We discuss the ecological and practical implications of the regulation approach and different mixing shares.

scholarly journals A meta-analysis on the impacts of partial cutting on forest structure and carbon storage

2013 ◽  
Vol 10 (6) ◽  
pp. 3691-3703 ◽  
Author(s):  
D. Zhou ◽  
S. Q. Zhao ◽  
S. Liu ◽  
J. Oeding
Keyword(s):  
Forest Structure ◽  
Forest Floor ◽  
Recovery Time ◽  
Mineral Soil ◽  
Basal Area ◽  
Partial Cutting ◽  
C Storage ◽  
Cutting Intensity ◽  
Stand Basal Area ◽  
Area And Volume

Abstract. Partial cutting, which removes some individual trees from a forest, is one of the major and widespread forest management practices that can significantly alter both forest structure and carbon (C) storage. Using 748 observations from 81 studies published between 1973 and 2011, we synthesized the impacts of partial cutting on three variables associated with forest structure (mean annual growth of diameter at breast height (DBH), stand basal area, and volume) and four variables related to various C stock components (aboveground biomass C (AGBC), understory C, forest floor C, and mineral soil C). Results show that the growth of DBH increased by 111.9% after partial cutting, compared to the uncut control, with a 95% bootstrapped confidence interval ranging from 92.2 to 135.9%, while stand basal area and volume decreased immediately by 34.2% ([−37.4%, −31.2%]) and 28.4% ([−32.0%, −25.1%]), respectively. On average, partial cutting reduced AGBC by 43.4% ([−47.7%, −39.3%]), increased understory C storage by 391.5% ([220.0%, 603.8%]), but did not show significant effects on C stocks on forest floor and in mineral soil. All the effects, if significant (i.e., on DBH growth, stand basal area, volume, and AGBC), intensified linearly with cutting intensity and decreased linearly over time. Overall, cutting intensity had more strong impacts than the length of recovery time on the responses of those variables to partial cutting. Besides the significant influence of cutting intensity and recovery time, other factors such as climate zone and forest type also affected forest responses to partial cutting. For example, a large fraction of the changes in DBH growth remains unexplained, suggesting the factors not included in the analysis may play a major role. The data assembled in this synthesis were not sufficient to determine how long it would take for a complete recovery after cutting because long-term experiments were scarce. Future efforts should be tailored to increase the duration of the experiments and balance geographic locations of field studies.

Red pine growth and chemical composition of foliage and forest floors across a precipitation-chemistry gradient in Wisconsin

1989 ◽  
Vol 19 (12) ◽  
pp. 1543-1549 ◽  
Author(s):  
J. G. Bockheim ◽  
J. E. Leide ◽  
L. E. Frelich
Keyword(s):  
Chemical Composition ◽  
Forest Floor ◽  
Growth Parameters ◽  
Basal Area ◽  
Site Index ◽  
Precipitation Chemistry ◽  
Red Pine ◽  
Radial Increment ◽  
Site Variation ◽  
Mass Concentrations

Three red pine (Pinusresinosa Ait.) plantations were located at each of five sites across the precipitation-chemistry gradient in Wisconsin (loadings of H ion, SO42−, and NO3− generally decrease from southeast to northwest). The plantations were selected to be as similar as possible in stand characteristics, including age, initial stocking, number of thinnings, site index, and basal area, and in soils (mixed frigid Typic Udipsamments or Entic Haplorthods). Despite the care exercised in selecting the plantations, analysis of variance incorporating a nested design showed that for the growth parameters, within-site variation generally was greater than among-site variation. The large within-site variation may have masked any differences attributable to variations in precipitation chemistry across the gradient. Site-related differences in radial increment (1982–1986 period) were attributed to time since thinning. There were significant site-related differences in mass, concentrations, and contents (mg/50 fascicles) of N, P, Ca, and S in current needles and in mass, concentrations, and contents (kg•ha−1) of N, P, and S in the forest floor. Differences in mass and chemical composition of needles among sites may be due to slight differences in soils. We attribute the differences in mass and chemical composition of the forest floor among sites to differences in preplanting site conditions and stand treatment.

Different nitrogen sources for fertilizing western hemlock in western Washington

1984 ◽  
Vol 14 (2) ◽  
pp. 155-162 ◽  
Author(s):  
M. A. Radwan ◽  
D. S. DeBell ◽  
S. R. Webster ◽  
S. P. Gessel
Keyword(s):  
Forest Floor ◽  
Mineral Soil ◽  
Volume Growth ◽  
Basal Area ◽  
N Fertilization ◽  
Height Growth ◽  
Growth Responses ◽  
Total N ◽  
Area Growth ◽  
Western Washington

Effects of different sources of fertilizer N on selected chemical characteristics of soils and foliage, and on growth of western hemlock (Tsugaheterophylla (Raf.) Sarg.) were compared at three different sites in western Washington. Treatments were the following: untreated control (O), ammonium nitrate (AN), ammonium sulfate (AS), calcium nitrate (CN), urea (U), and urea – ammonium sulfate (US). Fertilizers were applied in the spring (April–May) at 224 kg N/ha. Forest floor and mineral soil, to a depth of 5 cm, and foliage were sampled periodically for 2 years. Height and diameter of selected trees were measured periodically for 4 years. Results are reported mostly for two sites, one in the Cascade Range and one in the coastal zone in western Washington. The pH of forest floor and mineral soil varied by treatment, and the two urea fertilizers caused substantial initial rise. Effects on soil and foliar nutrients varied by fertilizer, sampling date, and location. In general, all fertilizers increased NH4 N, N03 N, and total N in the forest floor and mineral soil, and total N in the foliage. Also, with some exceptions, especially with foliar P in the Cascade site, fertilization reduced foliar content of important nutrients. At the Cascade site, 4-year growth responses in height, basal area, and volume averaged over all fertilizers were 30, 34, and 32%, respectively. AN, AS, CN, and urea resulted in height growth significantly (P < 0.20) higher than that of the control. Significant basal area growth and volume-growth responses were produced by AN, CN, and US. No significant height-growth response to any fertilizer occurred in the coastal stand; basal area growth and volume-growth responses averaged 27 and 21%, respectively, and best response occurred with urea. These results suggest that the low and inconsistent response of hemlock to N fertilization cannot be improved by applying some N fertilizer other than urea. Factors limiting response to N fertilization may be associated with availability of native N and other nutrients or other characteristics of hemlock sites and stands.

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