Wildlife-mitigated precommercial thinning maintains the abundance of fruit shrubs in a boreal forest

2013 ◽  
Vol 43 (3) ◽  
pp. 306-310 ◽  
Author(s):  
Mélanie Major ◽  
André Desrochers
Keyword(s):  
Species Composition ◽  
Boreal Forest ◽  
Boreal Forests ◽  
Late Summer ◽  
Diameter Growth ◽  
Precommercial Thinning ◽  
Wildlife Species ◽  
Abundance And Distribution ◽  
And Control ◽  
The Impact

In boreal forests, fruits are an abundant resource in late summer and benefit many wildlife species. Fruits are mainly found in early successional stands, which are often subject to precommercial thinning designed to increase diameter growth of residual trees and manage stand species composition. Concerns about the consequences of precommercial thinning on wildlife have led to various methods of precommercial thinning with mitigation for wildlife. In summers 2007 and 2008, we examined the impact of wildlife-mitigated thinning on fruit shrub abundance and distribution at the Forêt Montmorency, Quebec. The abundance of fruit shrubs of all species except Amelanchier was similar in thinned and control stands but was highly variable among individual stands. Amelanchier shrubs appeared to benefit from thinning, especially 10 to 20 years after clearcutting. Fruit shrubs were highly clustered within early successional stands, but less so after thinning. We conclude that wildlife-mitigated precommercial thinning does not reduce access to fruits for birds and other frugivores and may even facilitate it in eastern Canadian boreal forests.

scholarly journals The Dynamics of Transpiration to Evapotranspiration Ratio under Wet and Dry Canopy Conditions in a Humid Boreal Forest

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 237 ◽  
Author(s):  
Bram Hadiwijaya ◽  
Steeve Pepin ◽  
Pierre-Erik Isabelle ◽  
Daniel F. Nadeau
Keyword(s):  
Boreal Forest ◽  
Sap Flow ◽  
Boreal Forests ◽  
Cold Climate ◽  
Thermal Dissipation ◽  
Evaporative Demand ◽  
Sap Flux Density ◽  
Flow Measurements ◽  
Growing Seasons ◽  
The Impact

Humid boreal forests are unique environments characterized by a cold climate, abundant precipitation, and high evapotranspiration. Transpiration ( E T ), as a component of evapotranspiration (E), behaves differently under wet and dry canopy conditions, yet very few studies have focused on the dynamics of transpiration to evapotranspiration ratio ( E T / E ) under transient canopy wetness states. This study presents field measurements of E T / E at the Montmorency Forest, Québec, Canada: a balsam fir boreal forest that receives ∼ 1600 mm of precipitation annually (continental subarctic climate; Köppen classification subtype Dfc). Half-hourly observations of E and E T were obtained over two growing seasons using eddy-covariance and sap flow (Granier’s constant thermal dissipation) methods, respectively, under wet and dry canopy conditions. A series of calibration experiments were performed for sap flow, resulting in species-specific calibration coefficients that increased estimates of sap flux density by 34 % ± 8 % , compared to Granier’s original coefficients. The uncertainties associated with the scaling of sap flow measurements to stand E T , especially circumferential and spatial variations, were also quantified. From 30 wetting–drying events recorded during the measurement period in summer 2018, variations in E T / E were analyzed under different stages of canopy wetness. A combination of low evaporative demand and the presence of water on the canopy from the rainfall led to small E T / E . During two growing seasons, the average E T / E ranged from 35 % ± 2 % to 47 % ± 3 % . The change in total precipitation was not the main driver of seasonal E T / E variation, therefore it is important to analyze the impact of rainfall at half-hourly intervals.

Resilience of Alaska’s boreal forest to climatic changeThis article is one of a selection of papers from The Dynamics of Change in Alaska’s Boreal Forests: Resilience and Vulnerability in Response to Climate Warming.

2010 ◽  
Vol 40 (7) ◽  
pp. 1360-1370 ◽  
Author(s):  
F.S. Chapin ◽  
A.D. McGuire ◽  
R.W. Ruess ◽  
T.N. Hollingsworth ◽  
M.C. Mack ◽  
...  
Keyword(s):  
Rural Communities ◽  
Boreal Forest ◽  
Climate Warming ◽  
Boreal Forests ◽  
Structural Changes ◽  
Winter Season ◽  
Indigenous Communities ◽  
Structural Features ◽  
Temperature Sensitive ◽  
The Impact

This paper assesses the resilience of Alaska’s boreal forest system to rapid climatic change. Recent warming is associated with reduced growth of dominant tree species, plant disease and insect outbreaks, warming and thawing of permafrost, drying of lakes, increased wildfire extent, increased postfire recruitment of deciduous trees, and reduced safety of hunters traveling on river ice. These changes have modified key structural features, feedbacks, and interactions in the boreal forest, including reduced effects of upland permafrost on regional hydrology, expansion of boreal forest into tundra, and amplification of climate warming because of reduced albedo (shorter winter season) and carbon release from wildfires. Other temperature-sensitive processes for which no trends have been detected include composition of plant and microbial communities, long-term landscape-scale change in carbon stocks, stream discharge, mammalian population dynamics, and river access and subsistence opportunities for rural indigenous communities. Projections of continued warming suggest that Alaska’s boreal forest will undergo significant functional and structural changes within the next few decades that are unprecedented in the last 6000 years. The impact of these social–ecological changes will depend in part on the extent of landscape reorganization between uplands and lowlands and on policies regulating subsistence opportunities for rural communities.

scholarly journals Xylogenesis in black spruce subjected to rain exclusion in the field1This article is one of a selection of papers from the 7th International Conference on Disturbance Dynamics in Boreal Forests.

2012 ◽  
Vol 42 (7) ◽  
pp. 1306-1315 ◽  
Author(s):  
Evelyn Belien ◽  
Sergio Rossi ◽  
Hubert Morin ◽  
Annie Deslauriers
Keyword(s):  
Boreal Forest ◽  
Boreal Forests ◽  
Black Spruce ◽  
Water Status ◽  
Soil Horizon ◽  
Summer Drought ◽  
Normal Water ◽  
Short Time ◽  
And Control ◽  
Selection Of

The predicted climate warming and more frequent and longer droughts are expected to produce potentially severe water stresses in the boreal forest. The aim of this experiment was to study the effect of a summer drought on xylem phenology and anatomy of mature black spruce ( Picea mariana (Mill.) BSP) trees in their natural environment. The trees were excluded from rain during June–September 2010 by the installation of under-canopy roofs in four sites of the boreal forest of Quebec. Xylem phenology, stem radius variations, and physiological traits of treated and control trees were monitored at short time resolution. At the end of the growth season, cell characteristics were measured. The rain exclusion reduced the cell area of the xylem, but no significant change was observed in cell wall thickness, cell production, or phenology. Stem radius variations of the treated trees were lower but followed the same pattern as the control. After removal of the exclusion, trees and soil quickly recovered their normal water status. One summer of drought led to the formation of smaller tracheids but showed that black spruce is resistant to this rain exclusion treatment. This is likely due to the ability to collect water from sources other than the superficial soil horizon.

scholarly journals Methane emissions from boreal and tropical forest ecosystems derived from in-situ measurements

2007 ◽  
Vol 7 (5) ◽  
pp. 14011-14039 ◽  
Author(s):  
V. Sinha ◽  
J. Williams ◽  
P. J. Crutzen ◽  
J. Lelieveld
Keyword(s):  
Boreal Forest ◽  
Tropical Forest ◽  
Tropical Forests ◽  
Forest Ecosystem ◽  
Boreal Forests ◽  
Forest Ecosystems ◽  
Global Budget ◽  
Night Time ◽  
Mixing Ratios ◽  
The Impact

Abstract. Methane is a climatologically important greenhouse gas, which plays a key role in regulating water vapour in the stratosphere and hydroxyl radicals in the troposphere. Recent findings that vegetation emits methane have stimulated efforts to ascertain the impact of this source on the global budget. In this work, we present the results of high frequency (ca. 1 min−1) methane measurements conducted in the boreal forests of Finland and the tropical forests of Suriname, in April–May, 2005 and October 2005 respectively. The measurements were performed using a gas chromatograph – flame ionization detector (GC-FID). The average of the median mixing ratios during a typical diel cycle were 1.83 μmol mol−1 and 1.74 μmol mol−1 for the boreal forest ecosystem and tropical forest ecosystem respectively, with remarkable similarity in the time series of both the boreal and tropical diel profiles. Night time methane emission flux of the boreal forest ecosystem, calculated from the increase of methane during the night and measured nocturnal boundary layer heights yields a flux of (3.62±0.87)×1011 molecules cm−2 s−1(or 45.5±11 Tg CH4 yr−1 for global boreal forest area). This is a source contribution of circa 8% of the global methane budget. These results highlight the importance of the boreal and tropical forest ecosystems for the global budget of methane. The results are also discussed in the context of recent work reporting high methane mixing ratios over tropical forests using space borne near infra-red spectroscopy measurements.

scholarly journals Significant reduction in abundance of peridomestic mosquitoes (Culicidae) and Culicoides midges (Ceratopogonidae): an additional benefit of a novel attract-and-kill intervention applied against Leishmania infantum transmission, in São Paulo Brazil

2020 ◽  
Author(s):  
Mikel A. González ◽  
Erin Dilger ◽  
María M. Ronderos ◽  
Gustavo R. Spinelli ◽  
Orin Courtenay ◽  
...  
Keyword(s):  
Sao Paulo ◽  
Sand Fly ◽  
Randomised Control Trial ◽  
São Paulo ◽  
Mosquito Abundance ◽  
Household Level ◽  
Sleeping Sites ◽  
Abundance And Distribution ◽  
And Control ◽  
The Impact

Abstract Background Following the long-term (42-month) evaluation of residual insecticide (co-located with sand fly pheromone) and insecticide-impregnated dog-collars in a randomised control trial (RCT) against leishmaniasis, we assessed the impact of these interventions on the peridomestic abundance and distribution of mosquitoes (Culicidae) and midges (Ceratopogonidae) in Western São Paulo, Brazil. Both of these Dipteran groups are vectors of diseases of medical and veterinary relevance to humans and domestic animals in Brazil. Methods The interventions in the 3-arm RCT: pheromone + insecticide (PI) (chicken roosts sprayed with microencapsulated lambda-cyhalothrin), dog-collars (DC) (dogs fitted with deltamethrin-impregnated collars), and control (C) (unexposed to pyrethroids) were extended by 12 months. During that time adult mosquitoes and midges were sampled at three household locations (inside human dwellings, dog sleeping sites, chicken roosts). Results We collected 3,145 culicids (9 genera mostly Culex spp.) distributed relatively uniformly across all 3 arms; 43.5% inside houses, 36.2% at chicken roosts and 20.3% at dog sleeping sites. We collected 11,464 Culicoides (at least 15 species) found mostly at chicken roosting sites (84.7%) compared with dog sleeping sites (12.2%) or houses (3.1%). Mosquitoes and Culicoides were predominant during the hot and rainy reason. Increased daytime temperature was significantly associated with increased mosquito abundance (z = 1.97; P = 0.049) but marginally associated with Culicoides abundance (z = 1.71; P = 0.087). There was no significant association with average rainfall for either group. Household-level mosquito and midge numbers were both significantly reduced by the PI intervention 56% (Incidence Rate Ratio, IRR = 0.54 [95% C.I. 0.30, 0.97], P ≤ 0.05] and 53% (IRR = 0.47 [0.26, 0.85], P ≤ 0.05), respectively. The abundance of both Dipteran groups at dog sleeping sites was largely unaffected by the PI and DC interventions. The PI intervention significantly reduced abundance of mosquitoes inside houses (41%) and at chicken roosting sites (48%) and reduced midge abundance by 51% in chicken roosting sites. Conclusions Sprayed insecticide at chicken roosting sites reduced the abundance of mosquitoes and midges at the peridomestic level while dog collars had no effect on numbers for any group.

Snow removal reduces annual cellulose decomposition in a riparian boreal forest

2013 ◽  
Vol 93 (4) ◽  
pp. 427-433 ◽  
Author(s):  
Juergen Kreyling ◽  
Mahsa Haei ◽  
Hjalmar Laudon
Keyword(s):  
Boreal Forest ◽  
Snow Cover ◽  
Boreal Forests ◽  
Soil Depth ◽  
Decomposition Rates ◽  
Soil Frost ◽  
Snow Removal ◽  
Cellulose Decomposition ◽  
Significant Difference ◽  
The Impact

Kreyling, J., Haei, M. and Laudon, H. 2013. Snow removal reduces annual cellulose decomposition in a riparian boreal forest. Can. J. Soil Sci. 93: 427–433. Decomposition is a key process in carbon and nutrient cycling. However, little is known about its response to altered winter soil temperature regimes in boreal forests. Here, the impact of soil frost on cellulose decomposition over 1 yr and soil biotic activity (bait-lamina sticks) over winter, in spring, and in summer was investigated using a long-term (9-yr) snow-cover manipulation experiment in a boreal Picea abies forest. The experiment consisted of the treatments: snow removal, increased insulation, and ambient control. The snow removal treatment caused longer and deeper soil frost (minimum temperature −8.6°C versus −1.4°C) at 10 cm soil depth in comparison with control, while the increased insulation treatment resulted in nearly no soil frost during winter. Annual cellulose decomposition rates were reduced by 46% in the snow removal manipulation in comparison with control conditions. Increased insulation had no significant effect on decomposition. The decomposition was mainly driven by microorganisms, as no significant difference was observed for containers enclosed with a 44-µm and a 1-mm mesh. Soil biotic activity was slightly increased by both the snow removal and the increased insulation treatment in comparison with control conditions over winter. However, this effect disappeared over spring and summer. We conclude that soil frost can have strong effects on decomposition in boreal ecosystems. Further studies should investigate to which degree the observed reduction in decomposition due to reduced snow cover in winter slows or even offsets the expected increase in decomposition rates with global warming.

Effects of natural resource development on the terrestrial biodiversity of Canadian boreal forests

2014 ◽  
Vol 22 (4) ◽  
pp. 457-490 ◽  
Author(s):  
L.A. Venier ◽  
I.D. Thompson ◽  
R. Fleming ◽  
J. Malcolm ◽  
I. Aubin ◽  
...  
Keyword(s):  
Forest Management ◽  
Boreal Forest ◽  
Natural Resource ◽  
Boreal Forests ◽  
Large Scale ◽  
Resource Development ◽  
Natural Resource Development ◽  
Terrestrial Biodiversity ◽  
The Impact

Much of Canada’s terrestrial biodiversity is supported by boreal forests. Natural resource development in boreal forests poses risks to this biodiversity. This paper reviews the scientific literature to assess the effects of natural resource development on terrestrial biodiversity in Canadian boreal forests. We address four questions: (1) To what extent have Canadian boreal forests changed due to natural resource development? (2) How has biodiversity responded to these changes? (3) Will the biodiversity of second-growth forests converge with that of primary boreal forests? (4) Are we losing species from boreal forests? We focus on trees, understory plants, insects, fungi, selected mammals, and songbirds because these groups have been most studied. We review more than 600 studies and found that changes in community composition are prevalent in response to large-scale conversion of forest types, changes in stand structures and age distributions, and altered landscape structure resulting from forest management and habitat loss associated with other developments such as oil and gas, hydroelectric, and mining. The southern boreal forest has been more highly impacted than the north due to more extensive forest management and the cumulative effects of multiple forms of development. There is abundant evidence that most species are not in danger of being extirpated from the boreal forest due to these anthropogenic changes. A few species, including woodland caribou (Rangifer tarandus) and grizzly bear (Ursus arctos), have, however, undergone long-term range contractions. Significant gaps in our ability to assess the effects of natural resource development on biodiversity in the boreal zone are the lack of long-term spatial and population data to monitor the impact of forest changes on ecosystems and species.

Increasing nitrogen availability and soil temperature: effects on xylem phenology and anatomy of mature black spruce1This article is one of a selection of papers from the 7th International Conference on Disturbance Dynamics in Boreal Forests.

2012 ◽  
Vol 42 (7) ◽  
pp. 1277-1288 ◽  
Author(s):  
Carlo Lupi ◽  
Hubert Morin ◽  
Annie Deslauriers ◽  
Sergio Rossi ◽  
Daniel Houle
Keyword(s):  
Boreal Forest ◽  
Soil Temperature ◽  
Boreal Forests ◽  
Nitrogen Availability ◽  
Black Spruce ◽  
Anthropogenic Activities ◽  
N Availability ◽  
N Addition ◽  
Short Term Experiment ◽  
The Impact

Since plant growth in the boreal forest is often considered to be limited by low temperatures and low N availability and these variables are projected to increase due to climate warming and increased anthropogenic activities, it is important to understand whether and to what extent these disturbances may affect the growth of boreal trees. In this study, the hypotheses that wood phenology and anatomy were affected by increased soil temperatures and N depositions have been tested in two mature black spruce ( Picea mariana (Mill.) BSP) stands at different altitudes in Quebec, Canada. For 3 years, soil temperature was increased by 4 °C during the first part of the growing season and precipitations containing three times the current N concentration were added in the field by frequent canopy applications. Soil warming resulted in earlier onsets of xylogenesis and interacted with N addition producing longer durations of xylogenesis for the treated trees. The effect of warming was especially marked in the phenology of roots, while wood production, in terms of number of tracheids, was not affected by the treatment. Xylem anatomy and soil and needle chemistry showed no effect of the treatments, except for an increase of cell wall thickness in earlywood of treated trees. This short-term experiment with black spruce suggested that previous fertilization studies that used large and unrealistic rates of N addition may have overestimated the impact of N depositions on boreal forest productivity.

Suppressed, but Not Forgotten

2011 ◽  
Vol 70 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Beat Meier ◽  
Anja König ◽  
Samuel Parak ◽  
Katharina Henke
Keyword(s):  
Memory Trace ◽  
Thought Suppression ◽  
Test Phase ◽  
Indirect Test ◽  
Final Test ◽  
Test Experiment ◽  
And Control ◽  
Cue Words ◽  
The Impact

This study investigates the impact of thought suppression over a 1-week interval. In two experiments with 80 university students each, we used the think/no-think paradigm in which participants initially learn a list of word pairs (cue-target associations). Then they were presented with some of the cue words again and should either respond with the target word or avoid thinking about it. In the final test phase, their memory for the initially learned cue-target pairs was tested. In Experiment 1, type of memory test was manipulated (i.e., direct vs. indirect). In Experiment 2, type of no-think instructions was manipulated (i.e., suppress vs. substitute). Overall, our results showed poorer memory for no-think and control items compared to think items across all experiments and conditions. Critically, however, more no-think than control items were remembered after the 1-week interval in the direct, but not in the indirect test (Experiment 1) and with thought suppression, but not thought substitution instructions (Experiment 2). We suggest that during thought suppression a brief reactivation of the learned association may lead to reconsolidation of the memory trace and hence to better retrieval of suppressed than control items in the long term.

Research Participation Experiences of Informants of Suicide and Control Cases

Crisis ◽  
2010 ◽  
Vol 31 (5) ◽  
pp. 238-246 ◽  
Author(s):  
Paul W. C. Wong ◽  
Wincy S. C. Chan ◽  
Philip S. L. Beh ◽  
Fiona W. S. Yau ◽  
Paul S. F. Yip ◽  
...  
Keyword(s):  
Ethical Issues ◽  
Research Participation ◽  
Self Report ◽  
Initial Contact ◽  
Psychological Autopsy ◽  
Autopsy Study ◽  
The People ◽  
And Control ◽  
The Impact

Background: Ethical issues have been raised about using the psychological autopsy approach in the study of suicide. The impact on informants of control cases who participated in case-control psychological autopsy studies has not been investigated. Aims: (1) To investigate whether informants of suicide cases recruited by two approaches (coroners’ court and public mortuaries) respond differently to the initial contact by the research team. (2) To explore the reactions, reasons for participation, and comments of both the informants of suicide and control cases to psychological autopsy interviews. (3) To investigate the impact of the interviews on informants of suicide cases about a month after the interviews. Methods: A self-report questionnaire was used for the informants of both suicide and control cases. Telephone follow-up interviews were conducted with the informants of suicide cases. Results: The majority of the informants of suicide cases, regardless of the initial route of contact, as well as the control cases were positive about being approached to take part in the study. A minority of informants of suicide and control cases found the experience of talking about their family member to be more upsetting than expected. The telephone follow-up interviews showed that none of the informants of suicide cases reported being distressed by the psychological autopsy interviews. Limitations: The acceptance rate for our original psychological autopsy study was modest. Conclusions: The findings of this study are useful for future participants and researchers in measuring the potential benefits and risks of participating in similar sensitive research. Psychological autopsy interviews may be utilized as an active engagement approach to reach out to the people bereaved by suicide, especially in places where the postvention work is underdeveloped.

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