Dendrochronological evidence of shrub growth suppression by trees in a subarctic lichen woodland

Botany ◽  
2012 ◽  
Vol 90 (2) ◽  
pp. 151-156 ◽  
Author(s):  
Stéphane Boudreau ◽  
Marie-Pascale Villeneuve-Simard
Keyword(s):  
Black Spruce ◽  
Tree Cover ◽  
Shrub Species ◽  
Growth Variability ◽  
Dendrochronological Analysis ◽  
Lichen Cover ◽  
Tree Removal ◽  
Lichen Woodland ◽  
Few Data ◽  
Forested Ecosystems

Expansion of deciduous shrub species in open subarctic landscapes has been reported at several locations around the circumpolar region. However, few data are available to evaluate the response of shrub species in forested ecosystems. For this study, we conducted a dendrochronological analysis to compare the establishment and growth of Betula glandulosa Michx. individuals prior to and after an experimental removal of tree cover (1987) in a lichen woodland located at the boreal forest – tundra ecotone. Tree removal was followed by a B. glandulosa recruitment pulse. It is likely that the newly established seedlings benefited more from heavy trampling during tree removal, which destroyed the lichen cover, than from tree removal itself. A strong growth increase after tree removal suggests that the black spruce tree cover suppressed B. glandulosa growth prior to 1987. Moreover, while radial growth for the period prior to tree removal was not a function of the number of growing degree-days during the growing season, the same climatic variable explained 46% of the growth variability in the second period. These results suggest that the presence of a tree cover might limit the response of shrub species to climate change in forested ecosystems.

Studies on lichen-dominated systems. XIX. The postfire recovery sequence of black spruce – lichen woodland in the Abitau Lake Region, N.W.T.

1976 ◽  
Vol 54 (23) ◽  
pp. 2679-2687 ◽  
Author(s):  
E. Maikawa ◽  
K. A. Kershaw
Keyword(s):  
Northwest Territories ◽  
Black Spruce ◽  
Ground Cover ◽  
Final Phase ◽  
Recovery Sequence ◽  
Winter Range ◽  
Lake Region ◽  
Lichen Cover ◽  
Lichen Woodland ◽  
Associated Species

The postfire recovery sequence in spruce woodland growing on drumlins in the Abitau–Dunvegan Lakes area of the Northwest Territories is described. Four phases are recognized: year 1 to year 20, the Polytrichum phase dominated by P. piliferum, with Lecidea granulosa and L. uliginosa as associated species; year 21 to about year 60, the Cladonia phase dominated by Cladonia stellaris and C. uncialis; year 61 to about year 130, the spruce–Stereocaulon phase with Stereocaulon paschale forming an almost pure lichen ground cover; after year 130, the canopy closes and the lichen cover disappears and is replaced by a moss cover forming the final phase, spruce–moss woodland. These phases are confirmed by component analysis.The existence of spruce–Stereocaulon woodland in the area is thus dependent on cyclic burning. In the absence of fire the spruce canopy would close and the lichen cover would largely disappear. This event is rare in the area with a rebum cycle of about 100 years. Fire is thus an important vector in the maintenance of this extensive barren-ground caribou winter range.

Behaviour, habitat associations, and intrasexual differences of female Stone’s sheep

2006 ◽  
Vol 84 (8) ◽  
pp. 1187-1201 ◽  
Author(s):  
Andrew B.D. Walker ◽  
Katherine L. Parker ◽  
Michael P. Gillingham
Keyword(s):  
Habitat Use ◽  
Predation Risk ◽  
Growing Season ◽  
Early Summer ◽  
Habitat Associations ◽  
Phenological Stage ◽  
Shrub Species ◽  
Lichen Cover ◽  
Ovis Dalli ◽  
Maternal Status

Stone’s sheep ( Ovis dalli stonei Allen, 1897) in northern British Columbia segregate sexually during most of the year, and intrasexually between maternal and nonmaternal females during spring and early summer. Our objective was to quantify intrasexual habitat use of female Stone’s sheep relative to maternal status using measures of behaviour and habitat use. We reviewed three hypotheses of intersexual segregation (predation-risk, forage-selection, and activity-budget hypotheses) to determine if they also explained intrasexual segregation of female Stone’s sheep. Female Stone’s sheep spent the majority of their active time foraging. Nursery groups spent shorter durations of time active, more time active in solid rock escape features, and less time active in shrub habitat than nonmaternal groups. The best predictive model describing intrasexual differences incorporated distance to nearest escape feature and size of nearest escape feature. Regardless of maternal status, female Stone’s sheep used low-elevation plant communities early in the growing season that were characterized by more shrub species and increased cover. As the growing season progressed, they tracked a phenological stage, moving up in elevation and associating with communities that contained increasing amounts of moss and lichen cover. The patterns in behaviour, habitat use, and vegetation associations between intrasexual groups of Stone’s sheep were best characterized by the predation-risk hypothesis.

Dimension analysis of various components of black spruce in subarctic lichen woodland

1980 ◽  
Vol 10 (4) ◽  
pp. 491-497 ◽  
Author(s):  
Andrew N. Rencz ◽  
Allan N. Auclair
Keyword(s):  
Parabolic Equations ◽  
Individual Component ◽  
Black Spruce ◽  
Eastern Canada ◽  
Data Set ◽  
Dimension Analysis ◽  
Closed Forest ◽  
Lichen Woodland ◽  
Parabolic Form ◽  
Total Tree

Parabolic and logarithmic regressions were used to relate tree diameter to the biomass of root, root crown, bole, branch, needle, cone, and epiphytic lichens for a sample of 15 Piceamariana (Mill) trees occupying lichen woodland in the subarctic of eastern Canada. In 22 of 27 regressions both models yielded r2 values >0.82. Biomass estimates of total tree and individual component dry weights resulted in estimates with less than 6.5% difference between biomass estimates by logarithmic versus parabolic equations. For this data set the logarithmic model appeared more appropriate than the parabolic form. Validity of the regressions was judged on r2, analysis of variance, and examination of residuals. Equations generated in this study were considered to be inapplicable to P. mariana growing in closed forest. Problems in extrapolation were discussed.

Invertebrate predation of postdispersal seeds and juvenile seedlings of black spruce (Picea mariana) in the boreal forest of eastern Canada

2005 ◽  
Vol 35 (3) ◽  
pp. 674-681 ◽  
Author(s):  
Mathieu Côté ◽  
Jean Ferron ◽  
Réjean Gagnon
Keyword(s):  
Picea Mariana ◽  
Black Spruce ◽  
Pitfall Traps ◽  
Invertebrate Predation ◽  
Habitat Types ◽  
Eastern Canada ◽  
Exclosure Experiment ◽  
Seedling Predation ◽  
Lichen Woodland ◽  
Abundance And Diversity

We used an extensive vertebrate exclosure experiment to evaluate black spruce (Picea mariana (Mill.) B.S.P.) postdispersal seed and seedling predation by invertebrates in three boreal habitats of Eastern Canada: recent burn, spruce–moss, and lichen woodland. Between 9% and 19% of seeds were eaten by invertebrates. Seed predation was higher in recent burns than in spruce–moss and lichen woodlands. Abundance and diversity of potential invertebrate seed consumers sampled in pitfall traps also varied among habitat types. Among the invertebrate seed consumers sampled, Myrmica spp. (Hymenoptera: Formicidae) and Pterostichus adstrictus (Eschscholtz, 1823) (Coleoptera: Carabidae) were the most numerous; Formica spp. (Hymenoptera: Formicidae) and Pterostichus punctatissimus (Randall, 1838) (Coleoptera: Carabidae) were also present. Between 2% and 12% of juvenile black spruce seedlings were eaten by invertebrates. The most important seedling consumers were slugs (molluscs). Invertebrate predation of seeds and seedlings was highest (19% and 12%) in recent burns, indicating that invertebrate predation may significantly influence black spruce regeneration in these sites.

scholarly journals Regional Climate, Edaphic Conditions and Establishment Substrates Interact to Influence Initial Growth of Black Spruce and Jack Pine Planted in the Boreal Forest

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 139 ◽  
Author(s):  
Mohammed Henneb ◽  
Nelson Thiffault ◽  
Osvaldo Valeria
Keyword(s):  
Black Spruce ◽  
Wood Fiber ◽  
Regional Scale ◽  
Jack Pine ◽  
Growth Monitoring ◽  
Initial Growth ◽  
Eastern Canada ◽  
Growth Variability ◽  
Pinus Spp ◽  
Precipitation And Temperature

In eastern Canada, spruces (Picea spp.) and pines (Pinus spp.) are among the main commercial species being logged for their lumber or wood fiber. Annually, about 175 million seedlings are planted in areas totaling ~100,000 ha. Appropriate microsite selection is essential during reforestation operations, given that it can improve the chances of survival and initial growth of the seedlings. In fir (Abies spp.) and spruce forests of eastern Canada, the optimal characteristics of establishment microsites have yet to be identified; these would be determined by different physical and climatic variables operating at several scales. Our study determined the influence of climatic (regional-scale), edaphic (stand-scale), local (microsite-scale) and planting conditions on the establishment substrate and initial growth of black spruce (Picea mariana Britton, Sterns and Poggenb.) and jack pine (Pinus banksiana Lamb.). Substrate characterization and growth monitoring (three growing seasons) for the two species were conducted on 29 planted cutblocks that were distributed over an east–west climatic gradient (precipitation and temperature) in the balsam fir and black spruce–feather moss forests of Quebec (Canada). Linear mixed models and multivariate analyses (PCAs) determined the effects of climatic, edaphic and micro-environmental variables and their interactions on the establishment substrate and seedling initial growth. The predictive models explained, respectively, 61% and 75% of the growth variability of black spruce and jack pine. Successful establishment of black spruce and jack pine depended upon regional conditions of precipitations and temperature, as well as on their interactions with stand-scale edaphic variables (surface deposit, drainage and slope) and local variables (micro-environmental) at the microsite-scale (establishment substrate types and substrate temperature). Mineral, organo-mineral and organic establishment substrates exerted mixed effects on seedling growth according to regional precipitation and temperature conditions, as well as their interactions with edaphic and local variables at the stand and microsite-scales, respectively.

Songbird abundance in clear-cut and burned stands: a comparison of natural disturbance and forest management

2002 ◽  
Vol 32 (8) ◽  
pp. 1343-1350 ◽  
Author(s):  
N PP Simon ◽  
F E Schwab ◽  
R D Otto
Keyword(s):  
Forest Management ◽  
Picea Mariana ◽  
Black Spruce ◽  
Natural Disturbance ◽  
Tree Cover ◽  
Deciduous Tree ◽  
Clear Cut ◽  
Bird Density ◽  
Yellow Warblers ◽  
Successional Forests

To evaluate the efficacy of forest management to emulate natural disturbance, we compared bird abundances among burned and clear-cut, former black spruce (Picea mariana (Mill.) BSP) sites, after 5, 14, and 27 years of succession. Total bird density was lower in clear-cut sites resulting from fewer hermit thrushes, yellow warblers, Swainson's thrushes, and fox sparrows. Hermit thrushes were positively correlated with snag density while yellow warblers and Swainson's thrushes were positively associated with deciduous tree cover and negatively correlated with conifer cover. Only yellow-rumped warblers had higher densities on clear-cut sites, likely due to greater conifer cover. Bird densities and species richness peaked in the 14-year-old burns and exceeded that of mature forests reported for Labrador. This demonstrates the importance of natural early successional forests for birds. Although logged areas support several species found in natural young burns, logging does not precisely mimic fire. This suggests that forest managers should allow some forests to burn naturally.

Development of a simulation model of the forest–tundra transition zone of northeastern Canada

1994 ◽  
Vol 24 (4) ◽  
pp. 697-706 ◽  
Author(s):  
Luc Sirois ◽  
Gordon Blackwell Bonan ◽  
Herman Henry Shugart
Keyword(s):  
Forest Fires ◽  
Resource Constraints ◽  
Forest Succession ◽  
Black Spruce ◽  
Structural Characteristics ◽  
Fire Frequency ◽  
Lichen Woodland ◽  
Seed Regeneration ◽  
Gap Models ◽  
Subarctic Forest

A forest succession model has been adapted to simulate the dynamics of subarctic spruce–lichen woodland of northeastern Canada. Most adaptations concern the simulation of seed regeneration of subarctic forest communities growing on moderately to well drained sites. The yearly seed production in Piceamariana (Mill.) B.S.R stands is controlled by temperature and stand structural characteristics. In addition to the seed input, the model considers the influence of seedbed properties on the establishment of seedlings. Overall, this model simulates the entire regeneration dynamics in a more realistic way than in most other gap models where successional processes are driven by resource constraints on tree growth. The model produces realistic predictions about the pattern of early post-fire age structure, and the biomas and density dynamics of black spruce populations. Simulations under a climate-warming scenario suggest that physiognomic change in subarctic spruce–lichen woodland would be more pronounced in areas subjected to moderately frequent forest fires than in those where the fire frequency is very low.

Postfire seedling recruitment at the southern limit of lichen woodland

2009 ◽  
Vol 39 (12) ◽  
pp. 2299-2306 ◽  
Author(s):  
Melissa Moss ◽  
Luise Hermanutz
Keyword(s):  
Seedling Recruitment ◽  
Black Spruce ◽  
Burn Severity ◽  
Limited Data ◽  
Seedling Mortality ◽  
Southern Limit ◽  
Primary Mechanism ◽  
Variable Nature ◽  
Closed Canopy ◽  
Lichen Woodland

Although fire is the primary mechanism driving regeneration in open black spruce ( Picea mariana (Mill.) BSP) lichen woodland, there are limited data concerning the sources of seedling mortality across the range of burn severity. We monitored planted seedlings in areas of high and low burn severity in Terra Nova National Park (Newfoundland, Canada) to determine sources and patterns of mortality of black spruce seedlings among burn treatments following a recent burn (2002). The importance of herbivory by small mammals as a source of seedling mortality was evaluated using small cages that excluded voles and non-native snowshoe hare. Overall seedling mortality was high (79%) in all areas; mortality was similar in areas of low (73%) and high (76%) burn severity, and highest in edge areas adjacent to closed-canopy forest (90%). Drought, rather than herbivory, was the most common cause of mortality during the first two seasons following germination. Seedling mortality at the southern edge of the lichen woodland was comparable to that found in other studies, but sources differed, emphasizing the spatially variable nature of mortality. Based on the level of seedling recruitment, our results suggest lichen woodland will return at this site.

scholarly journals Fuel accumulation in a high-frequency boreal wildfire regime: from wetland to upland

2017 ◽  
Vol 47 (7) ◽  
pp. 957-964 ◽  
Author(s):  
D.K. Thompson ◽  
M.-A. Parisien ◽  
J. Morin ◽  
K. Millard ◽  
C.P.S. Larsen ◽  
...  
Keyword(s):  
High Frequency ◽  
Picea Glauca ◽  
Fire Regime ◽  
Black Spruce ◽  
Tree Cover ◽  
Regional Study ◽  
Fuel Loading ◽  
Canopy Fuels ◽  
Fuel Accumulation ◽  
Wood Buffalo National Park

Although it is increasingly accepted that young (e.g., ≤30 years) stands originating from wildfire are considerably less flammable than older stands in the boreal forest of North America, the role of fuel availability and structure in this phenomenon has not been thoroughly investigated. As a regional study in a high-frequency fire regime, detailed wildfire fuel loading and structure were measured in 66 sites including both wetlands and uplands in the Boreal Plains landscape of Wood Buffalo National Park in northwestern Canada. Overall, a significant increase in total flammable biomass occurred in upland sites over 97 years, but this increase was not consistently observed in wetlands, except where there was dense tree cover. Fuel accumulation was highly moderated by canopy fuels, as surface fuels were relatively constant across differing site types and time since fire, averaging 0.4 kg·m−2. Significant but gradual canopy fuel accumulation was observed in moist conifer upland forests dominated by mature black spruce (Picea mariana (Mill.) B.S.P.) or white spruce (Picea glauca (Moench) Voss) over 100 years since fire. Outside of these mature moist conifer uplands, there was no difference in total fuel loading between other upland forests and across the gradient of treed to open wetlands.

Quantification of Branch Dwelling Lichens for the Detection of Air Pollution Impact

1984 ◽  
Vol 16 (3) ◽  
pp. 297-304 ◽  
Author(s):  
P. A. Addison
Keyword(s):  
Oil Sands ◽  
Measurement Errors ◽  
Black Spruce ◽  
White Spruce ◽  
Pollution Source ◽  
Lichen Community ◽  
Naturally Occurring ◽  
Lichen Cover ◽  
Relative Errors

AbstractIn the Athabasca Oil Sands area of Alberta, a study was carried out to test a lichen community transplant technique and to determine the influence of oil sands extraction and processing emissions on lichen cover of transplanted communities. Measurement errors of a photographic technique for the determination of lichen cover were dependent upon lichen species but were not correlated to lichen cover. When lichen covers were small therefore, relative errors were very large. Changes in cover of naturally occurring lichen communities on black spruce branches were not significant over a four-year period. Lichen communities transplanted under jack pine and white spruce trees had cover changes with time not different from naturally occurring communities even over a period of years.Significant (P<0.001) cover reductions of some lichen groups occurred on transplanted branches under white spruce within 8–3 km of a pollution source. Evernia, Cetraria, and Bryoria groups were reduced whereas Hypogymnia showed no response over a 3 year measurement period. Reductions in lichen cover were greater than the demonstrated precision of the technique.

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