Effects of variable canopy retention harvest on epixylic bryophytes in boreal black spruce – feathermoss forests1This article is one of a selection of papers from the International Symposium on Dynamics and Ecological Services of Deadwood in Forest Ecosystems.

2012 ◽  
Vol 42 (8) ◽  
pp. 1467-1476 ◽  
Author(s):  
Julie Arseneault ◽  
Nicole J. Fenton ◽  
Yves Bergeron
Keyword(s):  
Environmental Change ◽  
Black Spruce ◽  
Control Variable ◽  
Permanent Plots ◽  
Canopy Openness ◽  
Forest Harvest ◽  
Single Pass ◽  
Local Species ◽  
Harvest Impact ◽  
Decomposition Class

Modification of forest attributes and structural components like downed wood (DW) during forest harvest can lead to local species loss. Epixylic bryophytes have been proposed as good indicators of such changes. Unharvested control, variable canopy retention, and single pass harvest represent a gradient in forest harvest impact and can be used to test the response of epixylic bryophytes to different levels of environmental change. The objective of this study was to see if variable canopy retention attenuates environmental change associated with harvesting, consequently maintaining an epixylic community more similar to unharvested stands than single pass harvesting. Environmental conditions and DW characteristics were sampled on 225 DW pieces distributed in 45 permanent plots. Results showed that treatment affected epixylic richness through its impact on canopy openness and DW diameter and decomposition class. Fewer species were found in more open habitats and more species were found on bigger and more decomposed DW. Most epixylic species were more commonly found on the forest floor than on the DW. In conclusion, variable canopy retention harvest offered microclimatic conditions and DW availability and quality more suitable for epixylic species than single pass harvest, which was less suitable for epixylic species.

Dispersal of Goeppertia marantifolia clonal offspring increases with greater canopy openness and larger plant size

2017 ◽  
Vol 33 (2) ◽  
pp. 107-113 ◽  
Author(s):  
David P. Matlaga ◽  
Rachel K. Snyder ◽  
Carol C. Horvitz
Keyword(s):  
Leaf Area ◽  
Light Availability ◽  
Plant Size ◽  
Dispersal Distance ◽  
Permanent Plots ◽  
Canopy Openness ◽  
Parent Plant ◽  
Analysis Model ◽  
Corcovado National Park ◽  
Positive Effect

Abstract:Many plants within the neotropical understorey produce both seeds and clonal offspring. Plant attributes (i.e. size) and variability in light can influence seed dispersal but it is not known if these factors influence the dispersal of clonal offspring. Our goal was to determine if canopy openness and plant size influence clonal-offspring dispersal of the herb Goeppertia marantifolia, which produces clonal bulbils on above-ground shoots. We monitored plants in permanent plots with varying levels of canopy openness in Corcovado National Park, Costa Rica. We recorded canopy openness, leaf area and the distance clonal offspring travelled from their parent plant (N = 283). Our path analysis model demonstrated that canopy openness had a strong positive effect on dispersal distance, while the association between clonal-offspring dispersal distance and parent plant leaf area was only weakly positive. On average, plants experiencing high canopy openness dispersed their clonal offspring further than plants under low canopy openness (124 cm vs. 79 cm, respectively). Contrary to studies on species that utilize rhizomes and stolons for clonal reproduction, we found that in this bulbil-producing species light availability is positively associated with clonal dispersal distance. Therefore, the influence of resource availability on spatial population dynamics of clonal species may be influenced by the species’ growth-form.

Effects of Continents and Supercontinents on Organic Evolution

2004 ◽  
Author(s):  
John J. W. Rogers ◽  
M. Santosh
Keyword(s):  
Environmental Change ◽  
Environmental Stress ◽  
Tectonic Activity ◽  
Continental Margins ◽  
Organic Evolution ◽  
Ocean Ridges ◽  
Large Numbers ◽  
Local Species ◽  
Orogenic Belts ◽  
Shallow Seas

The earth’s organic life has changed continually for more than 3.5 billion years. This evolution may have resulted partly from environmental stress generated by tectonic activity within the earth and partly from processes independent of the earth’s interior. This chapter investigates these different effects in an attempt to determine the role that continents played in the evolution of organisms. Continents and tectonics associated with them may have influenced organic evolution in both active and passive ways. Active effects include several processes that partly controlled the earth’s surface environment. Climate change was caused partly by movements of continents and construction of orogenic belts. Continental rifting increased the area of shallow seas as new continental margins subsided. Changes in volume of ocean ridges and epeiric movements of continents caused marine transgressions and regressions. Temperatures of water in shallow seas increased or decreased as continents moved across latitudes. The major passive effects of continents and supercontinents result from their influence on diversity of organisms. When continents were broadly dispersed and occupied most latitudes, as on the present earth, this isolation resulted in shallow-water and subaerial families that contained numerous genera, genera with large numbers of species, and species divided among many different varieties. This diversity was clearly smaller at times when continents were aggregated into a few landmasses and particularly low when supercontinents permitted exchange of organisms throughout most of the world’s land and shallow seas. During times of major environmental stress, these differences would have restricted extinction of organisms to local species and genera during times of high diversity but might have permitted disappearance of whole orders and classes when diversity was low. Organic evolution was almost certainly affected by species diversity, but it may have occurred without any active control by tectonic processes. Although evolution probably occurs only when changing environments place stresses on organisms that enhance the competition among them, it is also possible that competition between organisms can cause evolution even without significant environmental change. Furthermore, some environmental change probably resulted from processes that are not related to the tectonics of the solid earth.

scholarly journals Mechanisms by Which Pre-Commercial Thinning Increases Black Spruce Growth in Different Climates and Soil Types

Forests ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 599
Author(s):  
Amy Wotherspoon ◽  
Robert L. Bradley ◽  
Daniel Houle ◽  
Stéphane Tremblay ◽  
Martin Barrette ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Black Spruce ◽  
Canopy Openness ◽  
Soil N ◽  
Site Type ◽  
Commercial Thinning ◽  
Soil Moisture Availability ◽  
N Fertility ◽  
Competition For Resources ◽  
Site Types

In the province of Québec (Canada), pre-commercial thinning (PCT) is a common silvicultural practice applied to young black spruce (Picea mariana (Mill.) BSP) stands. PCT removes some of the competing vegetation and smaller black spruce stems, in order to improve growth rates and reduce forest rotation intervals. It is uncertain whether this positive response in black spruce growth is primarily due to lower competition for resources or to other mechanisms, which may vary according to climate or edaphic conditions. We sampled soils and black spruce needles in PCT-treated and non-treated control plots occurring in two climate regimes, as well as on two contrasting soil parent materials within one of these two climate regimes (i.e., three “site types”). We performed our sampling approximately 20 years after treatment. Paired treatment plots (i.e., PCT vs. control) were replicated at four independent sites in each of the three site types, for a total of 24 plots. Over two consecutive years, we measured stand structural characteristics, indices of soil N fertility, soil microbial activity, indices of soil moisture availability, canopy openness, and foliar characteristics in each plot. In each site type, PCT decreased total basal area but increased radial growth of individual trees. Across all plots, soil N mineralization rates measured in 2016 were positively related to foliar N concentrations of one-year-old needles collected in 2017. Annual precipitation, drainage class, potential evapotranspiration, and climate moisture index all indicated that plots occurring in the drier climate and on glacial till deposits were more prone to summer moisture deficits. Accordingly, PCT increased forest floor moisture only in this site type, which may benefit tree growth. In the wetter climate and on poorly drained soils, however, we found evidence that PCT reduces soil N fertility, presumably by increasing the spread of ericaceous shrubs in the understory. In the dry fertile site type, the range in canopy openness was substantially higher (12–37%) and correlated negatively with tree diameter, suggesting that greater light availability did not improve tree growth. Taken collectively, our data suggest that PCT increases black spruce growth across a broad range of site conditions found in Québec, presumably by lowering intraspecific competition for resources. However, on drier sites, PCT may also benefit trees by increasing soil moisture availability, whereas wetter climates may mitigate the beneficial effect of PCT due to a loss of soil N fertility.

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.

Changes in understory light regime in a beech–maple forest after a severe ice storm

2007 ◽  
Vol 37 (9) ◽  
pp. 1770-1776 ◽  
Author(s):  
Ken Arii ◽  
Martin J. Lechowicz
Keyword(s):  
Soil Surface ◽  
Deciduous Forests ◽  
Permanent Plots ◽  
Canopy Openness ◽  
Ice Storm ◽  
Ice Storms ◽  
Hemispherical Photographs ◽  
Shade Tolerant Species ◽  
The Mean ◽  
Canopy Damage

We assessed canopy openness (%) in an old-growth beech–maple forest immediately before and in the 3 years following a severe ice storm. We estimated canopy openness using hemispherical photographs taken at a height of 0.6 m above the soil surface in 101 permanent plots. Mean canopy openness increased from a prestorm value of 7.7% to 16.6% in the summer immediately following the storm. However, the mean canopy openness returned to prestorm levels within 3 years. The changes in canopy openness immediately after the storm were significantly influenced by canopy openness prior to the storm and also by species composition; plots with lower canopy openness prior to the storm and plots that consisted of more shade-tolerant species had greater canopy damage. While canopy gaps are often considered to promote the establishment of shade-intolerant species in the deciduous forests of eastern North America, gaps created by ice storms at our study site may not persist long enough to promote the establishment of these species.

Sphagnum establishment and expansion in black spruce (Picea mariana) boreal forests

2007 ◽  
Vol 85 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Nicole J. Fenton ◽  
Catherine Béland ◽  
Sylvie De Blois ◽  
Yves Bergeron
Keyword(s):  
Picea Mariana ◽  
Coarse Woody Debris ◽  
Boreal Forests ◽  
Forest Floor ◽  
Partial Correlation ◽  
Black Spruce ◽  
Woody Debris ◽  
Community Change ◽  
Control Factor ◽  
Canopy Openness

Boreal forest bryophyte communities are made up of distinct colonies of feathermosses that cover the forest floor. In some black spruce ( Picea mariana (Mill.) BSP) boreal forests, Sphagnum spp. establish colonies on the forest floor 30–40 years after the feathermosses, and ultimately expand to dominate the community. The mechanisms that permit the Sphagnum spp. to establish and expand are unknown. The objectives of this study were to examine the establishment and expansion substrates of Sphagnum spp., and the conditions correlated with colony expansion. Forty colonies, in six stands, of Sphagnum capillifolium (Ehrh.) Hedw. were dissected to determine their substrates, and the environmental conditions in which all colonies present were growing were measured. Coarse woody debris was the dominant establishment and early expansion substrate for Sphagnum capillifolium colonies. With age as the control factor, large colonies showed a significant partial correlation with canopy openness, and there were fewer individuals per cm3 in large colonies than there were in small colonies. These results suggest that Sphagnum establishment in these communities is dependent on the presence of coarse woody debris, and expansion is linked to the stand break-up, which would allow an increase in light intensity, and rainfall to reach the colony. Consequently the community change represented by Sphagnum establishment and expansion is initially governed by a stochastic process and ultimately by habitat availability and species competition.

Seasonal trends and effects of temperature and rainfall on stem electrical capacitance of spruce and fir trees

1990 ◽  
Vol 20 (7) ◽  
pp. 970-977 ◽  
Author(s):  
Timothy M. Lekas ◽  
R. Glenn MacDougall ◽  
David A. MacLean ◽  
Robert G. Thompson
Keyword(s):  
Black Spruce ◽  
Red Spruce ◽  
Annual Rainfall ◽  
Permanent Plots ◽  
Dry Period ◽  
Seasonal Trends ◽  
Influence Of Water ◽  
Effects Of Temperature ◽  
Relationship Of ◽  
The Relationship

Seasonal trends of stem capacitance were generally similar among balsam fir (Abiesbalsamea (L.) Mill.), white spruce (Piceaglauca (Moench) Voss), red spruce (Picearubens Sarg.), and black spruce (Piceamariana (Mill.) B.S.P.) trees and among plots. In 1987, stem capacitance increased following bud break until early June and then slowly declined until September 8, corresponding to an extended dry period (less than 27% of the annual rainfall of the previous 7 years). Dramatic increases in stem capacitance were observed following 55 mm of rain on September 9, 1987. During autumn of both 1987 and 1988, stem capacitance steadily declined; mean capacitance of trees in seven plots in October and November 1987 was 55–89 and 35–74% of values in June and July 1987, respectively. Diameter at breast height increment of 34 red spruce trees and 190 spruce and fir trees in permanent plots was consistently significantly (p <0.001) related to mean monthly capacitance; the strongest relationships (55–83% of the variability explained) were with mean June or July capacitance. The relationship of stem capacitance with growth of fir and spruce trees was corroborated. In addition, a stronger influence of water relations on capacitance than previously thought was demonstrated.

Post-wildfire seedbeds and tree establishment in the southern mixedwood boreal forest

2002 ◽  
Vol 32 (9) ◽  
pp. 1607-1615 ◽  
Author(s):  
I Charron ◽  
D F Greene
Keyword(s):  
Boreal Forest ◽  
Picea Glauca ◽  
Pinus Banksiana ◽  
Black Spruce ◽  
Mineral Soil ◽  
Jack Pine ◽  
Permanent Plots ◽  
First Year ◽  
Second Year ◽  
Mixedwood Boreal Forest

We studied the post-wildfire establishment of jack pine (Pinus banksiana Lamb.), black spruce (Picea mariana (Mill.) BSP), and white spruce (Picea glauca (Moench) Voss) in the southern mixedwood boreal forest of Saskatchewan, Canada. The major objective of the study was to determine the influence of post-wildfire seedbed types on the juvenile survivorship of trees. Through a combination of permanent plots and sowing experiments, we demonstrated that mineral soil, thin Polytrichum Hedw. moss, and humus are much more favorable than the organic fermentation (Of) and litter seedbeds. We also show that differences among seedbeds are significantly more important than differences among species. In addition, the first year of a cohort has the highest rate of mortality, about 85% on mineral and humus seedbeds and 98% on Of seedbeds; differences in age-specific survivorship between seedbeds become muted by the end of the second year, and survivorship rates approach 1 by the end of the third summer. Finally, age structures showed that germination rates of black spruce and jack pine were very low the initial summer of the fire; that there was a peak in recruitment in the first post-fire summer; and that by the fourth year the recruitment declined to nearly zero.

Plant communities of Voyageurs National Park, Minnesota, U.S.A.

1986 ◽  
Vol 64 (3) ◽  
pp. 531-540 ◽  
Author(s):  
Vilis Kurmis ◽  
Sara L. Webb ◽  
Lawrence C. Merriam Jr.
Keyword(s):  
Plant Communities ◽  
National Park ◽  
Management Practices ◽  
Black Spruce ◽  
Permanent Plots ◽  
Community Classification ◽  
Voyageurs National Park ◽  
Plant Community Classification ◽  
Ecological Type ◽  
Ecological Types

The vegetation of Voyageurs National Park, Minnesota, U.S.A., was investigated, in part to establish a plant community classification system that would be useful to park managers and naturalists, and to evaluate short-term changes within plant communities. Samples from 120 stands were ordinated and classified on the basis of synecological coordinates, a system of ecological coordinates relating floristics to physical site conditions. Along indirect gradients of moisture and nutrient conditions, 12 ecological types were distinguished. Within each ecological type, it is expected that stands of diverse cover types will tend to converge, over a period of 150–200 years, on an edaphically constrained “climax” community characteristic of that ecological type, given present management practices and disturbance regimes. Permanent plots were established in 46 stands to permit future testing of these projections. Ecological types, named for expected dominants and for a typical undergrowth species or genus, include (1) jack pine – oak – Arctostaphylos; (2) red pine – white pine – Linnaea; (3) fir–spruce–birch–Lycopodium; (4) fir–birch–Mitella; (5) oak–maple–Uvularia; (6) ash–elm–Trillium; (7) black ash – Caltha; (8) white cedar – Coptis; (9) black spruce – Alnus; (10) black spruce – Kalmia; (11) leatherleaf (Chamaedaphne) bog; and (12) marsh.

Modelling moss-derived carbon in upland black spruce forests

2016 ◽  
Vol 46 (4) ◽  
pp. 520-534 ◽  
Author(s):  
Kelly Ann Bona ◽  
Cindy H. Shaw ◽  
James W. Fyles ◽  
Werner A. Kurz
Keyword(s):  
Large Scale ◽  
Fire Regime ◽  
Black Spruce ◽  
Ground Cover ◽  
Tree Canopy ◽  
Canopy Openness ◽  
Organic Layer ◽  
Feather Moss ◽  
C Cycle ◽  
Scale Variation

Mosses play a key role in the carbon (C) cycle of upland black spruce (Picea mariana (Mill.) BSP) forests; however, national reporting models such as the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) do not include mosses. This study examined whether widely available plot-level merchantable tree volume could predict, for black spruce ecosystems in Canada’s boreal forest, the relative proportions of sphagnum and feather moss ground cover and moss net primary productivity (NPP). A field study found that merchantable tree volume was significantly related to tree canopy openness (R2 = 0.61, P < 0.001), which could then be used to model the relative ground cover of feather moss (R2 = 0.5, P < 0.001) and sphagnum (R2 = 0.45, P < 0.001) and NPP of feather moss (R2 = 0.41, P < 0.001) and sphagnum (R2 = 0.28, P < 0.001). The resulting MOSS-C submodel increased the accuracy of the CBM-CFS3’s prediction of organic-horizon C five-fold and could explain large-scale variation in sites dominated by sphagnum with large organic-layer C pools but not fine-scale variation in dryer sites. To improve MOSS-C accuracy, future studies should focus on varying decomposition and fire regime parameters based on regional climate or plot-level vegetation parameters.

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