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.

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.

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.

Spatial patterns of soil and vegetation in a 40-year-old slash pine (Pinus elliottii) forest in the Coastal Plain of South Carolina, U.S.A.

2000 ◽  
Vol 30 (1) ◽  
pp. 145-155 ◽  
Author(s):  
Andrew J Lister ◽  
Paul P Mou ◽  
Robert H Jones ◽  
Robert J Mitchell
Keyword(s):  
South Carolina ◽  
Spatial Patterns ◽  
Forest Floor ◽  
Basal Area ◽  
Woody Species ◽  
Pinus Elliottii ◽  
Structural Heterogeneity ◽  
Slash Pine ◽  
Ecological Processes ◽  
Soil Variables

A study was conducted at the Savannah River Site in a 40-year-old slash pine (Pinus elliottii Engelm.) plantation in South Carolina to characterize the spatial patterns of soil, forest floor, and plant community variables and to investigate correlations among the variables. Spatial soil and litter samples were collected on five 0.25-ha plots. The spatial patterns of the variables were characterized by global variance, autocorrelation range, and patchiness. The cross-variable relationships were explored using Pearson's correlation tests to examine functional heterogeneity (i.e., to determine if structural heterogeneity reflected ecological processes). Variances of the variables calculated without regard to spatial position (i.e., global variance) were generally low. Average range of spatial autocorrelation was about 58 m for the forest floor variables, 11 m for soil variables, 11 m for basal area of large pines (>30 cm diameter at breast height), and less than 11 m for basal area of smaller pines or other woody species. Few strong spatial correlations among the forest floor and soil variables were observed. Spatial patterns of pines and hardwoods were weakly correlated with litter quality patterns and soil nitrogen. We conclude that the sample plots were generally homogeneous and that differences in soil resource levels were probably too small to influence spatial pattern of vegetation in this 40-year-old plantation.

scholarly journals Short Term Impacts of Harvesting 0perations on Soil Chemical Properties in a Mediterranean Oak Ecosystem

2021 ◽  
Vol 42 (3) ◽  
Author(s):  
Harisios P. Ganatsios ◽  
Petros A. Tsioras ◽  
Athanassios G. Papaioannou ◽  
Charles R. Blinn
Keyword(s):  
Forest Floor ◽  
Soil Depth ◽  
Chemical Properties ◽  
Basal Area ◽  
Small Scale ◽  
Multiple Use ◽  
Northern Greece ◽  
Protective Function ◽  
Clear Cut ◽  
Oak Ecosystem

Soil physical and chemical properties can be seriously affected by forest operations. There is a knowledge gap on this topic for oak ecosystems, which can play a significant role in the context of multiple-use forestry. The main objective of this study was to analyse forest floor and topsoil changes (0–10 cm) two years after the application of small-scale thinning (50% reduction of basal area) and clear-cut operations using mules to carry harvested material in a Northern Greece oak (Quercus frainetto Ten)ecosystem. The total amount of forest floor (O1+O2 horizons) was reduced by 37.8% in the thinned and 30.8% in the clear-cut plots compared to control plots. These large reductions are mainly due to reduction in the O2 horizon in the treated plots. Decomposition was reduced in the treated plots, possibly due to the new drier conditions. Treatments increased the soil pH but not to a significant extent. No evidence of erosion was found in the experimental plots due to the protective function of the forest floor and the use of designated mule trails. The areal extent of soil compaction was limited to only 3% of the total area mainly due to the careful planning and implementation of animal skidding. Small differences in C (%) and Ν (%) were found among control, thinned and clear-cut plots. The limiting growth factors in Mediterranean oak ecosystems are soil depth and the seasonal change of soil moisture, especially during the summer dry period. More research on the definition of the optimum thinning degree and extraction systems in similar ecosystems will be important to satisfy the need to improve soil characteristics.

Effects of chronic nitrogen additions on nitrogen cycling in a high-elevation spruce–fir stand

1993 ◽  
Vol 23 (7) ◽  
pp. 1252-1263 ◽  
Author(s):  
S.G. McNulty ◽  
J.D. Aber
Keyword(s):  
N Mineralization ◽  
Forest Floor ◽  
Basal Area ◽  
Ion Exchange Resin ◽  
High Elevation ◽  
N Fertilization ◽  
First Year ◽  
Net N Mineralization ◽  
Living Dead ◽  
A Site

A 3-year low-level (15–31 kg N•ha−1•year−1) fertilization treatment was conducted in a high-elevation spruce–fir stand, on Mount Ascutney, Vermont. Shortly after fertilization, large concentrations (≤ 900 ppm) of both NH4-N and NO3-N were recovered in ion-exchange resin bags buried at the base of the forest floor. Despite an initial loss of added N, we found significant correlations between the amount of fertilizer applied and measured ecosystem parameters. Bulk deposition for the plots equalled 5.1 kg N•ha−1•year−1, of which 50% fell as NO3-N in snow. No correlations were found between the amount of N applied to a site and throughfall N concentration of the site. Increased Basal Area (BA) growth was recorded using two separate techniques, with the greatest increases in living BA occurring on the 25.6 kg N•ha−1year−1 treatment. As N fertilization increased, foliar %N, net forest floor net N mineralization, dead BA, total (living + dead) BA, first year net N mineralization, and coniferous and deciduous litter %N also increased. On plots receiving high rates of fertilization, net N mineralization rates remained constant or decreased during the third year while low N addition plots experienced increased net N mineralization rates, suggesting a possible C limitation. These results indicate that these slow growing, nutrient conserving ecosystems are responsive to even small increases in N inputs.

Geostatistically modeling stem size and increment in an old-growth forest

1994 ◽  
Vol 24 (7) ◽  
pp. 1354-1368 ◽  
Author(s):  
Franco Biondi ◽  
Donald E. Myers ◽  
Charles C. Avery
Keyword(s):  
Spatial Patterns ◽  
Growth Rates ◽  
Spatial Dependence ◽  
Basal Area ◽  
Tree Density ◽  
Individual Growth ◽  
Old Growth ◽  
Model Estimate ◽  
Stem Size ◽  
Old Growth Forest

Geostatistics provides tools to model, estimate, map, and eventually predict spatial patterns of tree size and growth. Variogram models and kriged maps were used to study spatial dependence of stem diameter (DBH), basal area (BA), and 10-year periodic basal area increment (BAI) in an old-growth forest stand. Temporal variation of spatial patterns was evaluated by fitting spatial stochastic models at 10-year intervals, from 1920 to 1990. The study area was a naturally seeded stand of southwestern ponderosa pine (Pinusponderosa Dougl. ex Laws. var. scopulorum) where total BA and tree density have steadily increased over the last decades. Our objective was to determine if increased stand density simply reduced individual growth rates or if it also altered spatial interactions among trees. Despite increased crowding, stem size maintained the same type of spatial dependence from 1920 to 1990. An isotropic Gaussian variogram was the model of choice to represent spatial dependence at all times. Stem size was spatially autocorrelated over distances no greater than 30 m, a measure of average patch diameter in this forest ecosystem. Because patch diameter remained constant through time, tree density increased by increasing the number of pine groups, not their horizontal dimension. Spatial dependence of stem size (DBH and BA) was always much greater and decreased less through time than that of stem increment (BAI). Spatial dependence of BAI was close to zero in the most recent decade, indicating that growth rates in 1980–1990 varied regardless of mutual tree position. Increased tree crowding corresponded not only to lower average and variance of individual growth rates, but also to reduced spatial dependence of BAI. Because growth variation was less affected by intertree distance with greater local crowding, prediction of individual growth rates benefits from information on horizontal stand structure only if tree density does not exceed threshold values. Simulation models and area estimates of tree performance in old-growth forests may be improved by including geostatistical components to summarize ecological spatial dependence.

Short-term effects of timber harvest and forest edges on ground-layer mosses and liverworts

2005 ◽  
Vol 83 (6) ◽  
pp. 610-620 ◽  
Author(s):  
Cara R Nelson ◽  
Charles B Halpern
Keyword(s):  
Forest Management ◽  
Edge Effects ◽  
Management Practices ◽  
Timber Harvest ◽  
Ground Layer ◽  
Limited Information ◽  
Short Term ◽  
Before And After ◽  
Logging Effects ◽  
Structural Retention

Limited information exists on the effects of forest management practices on bryophytes, despite their importance to forest ecosystems. We examined short-term responses of ground-layer bryophytes to logging disturbance and creation of edges in mature Pseudotsuga forests of western Washington (USA). The abundance and richness of species were measured in four 1-ha forest aggregates (patches of intact forest) and in surrounding logged areas before and after structural retention harvests. One year after treatment, species richness, total cover, and frequency of most moss and liverwort taxa declined within harvest areas. Within forest aggregates, mosses did not show significant edge effects; however, richness and abundance of liverworts declined with proximity to the aggregate edge. Our results suggest that, over short time frames, 1-ha-sized aggregates are sufficient to maintain most common mosses through structural retention harvests but are not large enough to prevent declines or losses of liverworts. Thus, current standards for structural retention, which allow for aggregates as small as 0.2 ha, may be inadequate to retain the diversity and abundance of species found in mature, undisturbed forests.Key words: bryophyte, edge effects, forest borders, forest management, logging effects, structural retention harvest.

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 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.

The effect of spatially variable overstory on the understory light environment of an open-canopied longleaf pine forest

2002 ◽  
Vol 32 (11) ◽  
pp. 1984-1991 ◽  
Author(s):  
Michael A Battaglia ◽  
Pu Mou ◽  
Brian Palik ◽  
Robert J Mitchell
Keyword(s):  
Spatial Variation ◽  
Spatial Patterns ◽  
Longleaf Pine ◽  
Light Availability ◽  
Canopy Structure ◽  
Basal Area ◽  
Pinus Palustris ◽  
Pine Forest ◽  
Large Group ◽  
The Relationship

Spatial aggregation of forest structure strongly regulates understory light and its spatial variation in longleaf pine (Pinus palustris Mill.) forest ecosystems. Previous studies have demonstrated that light availability strongly influences longleaf pine seedling growth. In this study, the relationship between spatial structure of a longleaf pine forest and spatial pattern of understory light availability were investigated by comparing three retention harvest treatments: single-tree, small-group, large-group, and an uncut control. The harvests retained similar residual basal area but the spatial patterns of the residual trees differed. Hemispherical photographs were taken at 300 stations to calculate gap light index (GLI), an estimate of understory light availability. Stand-level mean, variation, and spatial distribution of GLI were determined for each treatment. By aggregating residual trees, stand mean GLI increased by 20%, as well as its spatial variation. Spatial autocorrelation of GLI increased as the size of the canopy gaps increased and the gaps were better defined; thus, the predictability of GLI was enhanced. The ranges of detrended semivariograms were increased from the control to the large-group harvest indicating the spatial patterns of understory GLI became coarser textured. Our results demonstrated that aggregated canopy structure of longleaf pine forest will facilitate longleaf pine seedling regeneration.

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