Origin of the lichen woodland at its southern range limit in eastern Canada: the catastrophic impact of insect defoliators and fire on the spruce-moss forest

2000 ◽  
Vol 30 (2) ◽  
pp. 288-305 ◽  
Author(s):  
Serge Payette ◽  
Najat Bhiry ◽  
Ann Delwaide ◽  
Martin Simard

The lichen woodland is one of the most important forest ecosystems in North America, dominating the central part of the boreal forest. The southernmost lichen woodland is paradoxically in the heart of the southern boreal forest. This distribution prompted this study aiming to identify the factors responsible for the inception and development of the lichen woodland at its southern range limit in eastern Canada. We tested the hypothesis that the southern lichen-spruce woodland is a regressive, post-fire type of the spruce-moss forest. We studied adjacent lichen-spruce and spruce-moss stands growing under similar soil conditions. We reconstructed the recent history of spruce-moss forest transformation to lichen woodland using tree size, tree ring patterns, and macrofossil analysis of organic soil. All the plant macrofossils buried in the unburned organic mat below the charcoal layer of the last fire corresponded to a feather-moss forest assemblage and included head capsules of the spruce budworm (Choristoneura fumiferana (Clem.)) or European spruce sawfly (Gilpinia hercyniae Hartig.). The impact of combined insect and fire disturbances translates into a dramatic decrease in post-fire tree regeneration of the forest inducing the shift to lichen woodland. The inception of the southern lichen woodland highlights the fragility of the spruce-moss forest even in the core area of the southern commercial boreal forest.

Ecosystems ◽  
2021 ◽  
Author(s):  
Theresa S. Ibáñez ◽  
David A. Wardle ◽  
Michael J. Gundale ◽  
Marie-Charlotte Nilsson

AbstractWildfire disturbance is important for tree regeneration in boreal ecosystems. A considerable amount of literature has been published on how wildfires affect boreal forest regeneration. However, we lack understanding about how soil-mediated effects of fire disturbance on seedlings occur via soil abiotic properties versus soil biota. We collected soil from stands with three different severities of burning (high, low and unburned) and conducted two greenhouse experiments to explore how seedlings of tree species (Betula pendula, Pinus sylvestris and Picea abies) performed in live soils and in sterilized soil inoculated by live soil from each of the three burning severities. Seedlings grown in live soil grew best in unburned soil. When sterilized soils were reinoculated with live soil, seedlings of P. abies and P. sylvestris grew better in soil from low burn severity stands than soil from either high severity or unburned stands, demonstrating that fire disturbance may favor post-fire regeneration of conifers in part due to the presence of soil biota that persists when fire severity is low or recovers quickly post-fire. Betula pendula did not respond to soil biota and was instead driven by changes in abiotic soil properties following fire. Our study provides strong evidence that high fire severity creates soil conditions that are adverse for seedling regeneration, but that low burn severity promotes soil biota that stimulates growth and potential regeneration of conifers. It also shows that species-specific responses to abiotic and biotic soil characteristics are altered by variation in fire severity. This has important implications for tree regeneration because it points to the role of plant–soil–microbial feedbacks in promoting successful establishment, and potentially successional trajectories and species dominance in boreal forests in the future as fire regimes become increasingly severe through climate change.


2013 ◽  
Vol 13 (13) ◽  
pp. 6239-6261 ◽  
Author(s):  
P. I. Palmer ◽  
M. Parrington ◽  
J. D. Lee ◽  
A. C. Lewis ◽  
A. R. Rickard ◽  
...  

Abstract. We describe the design and execution of the BORTAS (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites) experiment, which has the overarching objective of understanding the chemical aging of air masses that contain the emission products from seasonal boreal wildfires and how these air masses subsequently impact downwind atmospheric composition. The central focus of the experiment was a two-week deployment of the UK BAe-146-301 Atmospheric Research Aircraft (ARA) over eastern Canada, based out of Halifax, Nova Scotia. Atmospheric ground-based and sonde measurements over Canada and the Azores associated with the planned July 2010 deployment of the ARA, which was postponed by 12 months due to UK-based flights related to the dispersal of material emitted by the Eyjafjallajökull volcano, went ahead and constituted phase A of the experiment. Phase B of BORTAS in July 2011 involved the same atmospheric measurements, but included the ARA, special satellite observations and a more comprehensive ground-based measurement suite. The high-frequency aircraft data provided a comprehensive chemical snapshot of pyrogenic plumes from wildfires, corresponding to photochemical (and physical) ages ranging from < 1 day to ~


Author(s):  
Aleksey S. Ilintsev ◽  
◽  
Elena N. Nakvasina ◽  
Lars Högbom ◽  
◽  
...  

Public opinion has become increasingly critical of current logging methods and technologies, and there is a demand for standards to guide the operations of environmentally impactful industries. For many years, numerous researchers have studied the impact of logging on forest soils, revealing that there is a high risk of damaging forest soil during forest operations and terrain transport. Here we analyse and review a total of 105 publications in this area. This large body of work demonstrates the scientific interest that this field has attracted. Despite this, important areas of uncertainty concerning the impact of forest harvesting still remain. In particular, changes in soil conditions can affect soil properties in ways that are not well understood, with possible impacts on the physical, chemical, and biological properties of soils as well as the structure of the soil cover. While it is difficult to fully eliminate the negative impact of forest operations on forest soils, their adverse environmental consequences should be minimised because soil plays a vital role in tree regeneration and helps determine the productivity of future forest stands. Some of the most frequently cited measures and effective technological solutions to minimize damage to forest soils involve taking terrain and different technical solutions into account when organising logging operations. Potentially helpful technical solutions include selecting machines and mechanisms suitable for the site conditions, using larger and/or low-pressure tyres, using tyre pressure control, using anti-skid tracks, using track belts, meliorating wet areas, and using logging machinery incorporating global positioning systems and geographic information systems. Planning measures that can help minimize soil damage include choosing a suitable wood harvesting system and technology, accounting for seasonal factors when planning logging operations, planning networks of roads and trails in advance, leaving wood residues or mats on soil surface, training forest specialists, and reducing the number of machine passes over skid trails and strip roads. Despite active interest in applying sparing methods of wood harvesting, uptake of measures designed to reduce negative impacts on forest soils after logging has been limited. This may be due to a lack of scientific and technical information and the high cost of implementing best management practices. Moreover, economic factors and production plans may require wood harvesting throughout the year, irrespective of conditions. For citation: Ilintsev A.S., Nakvasina E.N., Högbom L. Methods of Protection Forest Soils during Logging Operations (Review). Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 5, pp. 92–116. DOI: 10.37482/0536-1036-2021-5-92-116


2013 ◽  
Vol 13 (2) ◽  
pp. 4127-4181 ◽  
Author(s):  
P. I. Palmer ◽  
M. Parrington ◽  
J. D. Lee ◽  
A. C. Lewis ◽  
A. R. Rickard ◽  
...  

Abstract. We describe the design and execution of the BORTAS (Quantifying the impact of BOReal forest fires on Tropospheric oxidants using Aircraft and Satellites) experiment, which has the overarching objective of understanding the chemical aging of airmasses that contain the emission products from seasonal boreal wildfires and how these airmasses subsequently impact downwind atmospheric composition. The central focus of the experiment was a two-week deployment of the UK BAe-146-301 Atmospheric Research Aircraft (ARA) over eastern Canada. The planned July 2010 deployment of the ARA was postponed by 12 months because of activities related to the dispersal of material emitted by the Eyjafjallajökull volcano. However, most other planned model and measurement activities, including ground-based measurements at the Dalhousie University Ground Station (DGS), enhanced ozonesonde launches, and measurements at the Pico Atmospheric Observatory in the Azores, went ahead and constituted phase A of the experiment. Phase B of BORTAS in July 2011 included the same measurements, but included the ARA, special satellite observations and a more comprehensive measurement suite at the DGS. The high-frequency aircraft data provided a comprehensive snapshot of the pyrogenic plumes from wildfires. The coordinated ground-based and sonde data provided detailed but spatially-limited information that put the aircraft data into context of the longer burning season. We coordinated aircraft vertical profiles and overpasses of the NASA Tropospheric Emission Spectrometer and the Canadian Atmospheric Chemistry Experiment. These space-borne data, while less precise than other data, helped to relate the two-week measurement campaign to larger geographical and longer temporal scales. We interpret these data using a range of chemistry models: from a near-explicit gas-phase chemical mechanism, which tests out understanding of the underlying chemical mechanism, to regional and global 3-D models of atmospheric transport and lumped chemistry, which helps to assess the performance of the simplified chemical mechanism and effectively act as intermediaries between different measurement types. We also present an overview of some of the new science that has originated from this project from the mission planning and execution to the analysis of the ground-based, aircraft, and space-borne data.


1982 ◽  
Vol 12 (4) ◽  
pp. 947-968 ◽  
Author(s):  
Allan N. D. Auclair ◽  
Andrew N. Rencz

The concentration and mass of nutrient elements (N, P, K, Ca, Mg, Cu, Fe, Mn, Na, Zn) were examined in 110-year-old lichen woodland in the subarctic of eastern Canada. Biomass plus soil organic matter contained two-fifths (41%) of the total nutrient mass in the system. Calcium (85%), P (76%), Mg (67%), and K (64%) were largely in live biomass. Nitrogen was equally in biomass plus organic soil (45%) and mineral soil (55%). Micronutrients were mainly in the soil inorganic fraction. Nitrogen was acutely deficient for rapid growth. Potential loss of Ca under logging and burning regimes consistently exceeded exchangeable soil reserves. A realistic evaluation of these impacts was dependent on more complete knowledge of net atmospheric and soil inputs and vegetation requirements. Dominant tree, shrub, and lichen genera all differed strongly in the concentration of tissue elements. Among vascular species, total element concentration related inversely to species abundance. Since evergreen perennial plants of low nutrient concentration prevailed at maturity, we postulated that nutrients increasingly limited the abundance of deciduous shrubs.


Author(s):  
Mihail Zver'kov

To the article the results of the theoretical and experimental researches are given on questions of estimates of the dynamic rate effect of raindrop impact on soil. The aim of this work was to analyze the current methods to determine the rate of artificial rain pressure on the soil for the assessment of splash erosion. There are the developed author’s method for calculation the pressure of artificial rain on the soil and the assessment of splash erosion. The study aims to the justification of evaluation methods and the obtaining of quantitative characteristics, prevention and elimination of accelerated (anthropogenic) erosion, the creation and the realization of the required erosion control measures. The paper considers the question of determining the pressure of artificial rain on the soil. At the moment of raindrops impact, there is the tension in the soil, which is called vertical effective pressure. It is noted that the impact of rain drops in the soil there are stresses called vertical effective pressure. The equation for calculation of vertical effective pressure is proposed in this study using the known spectrum of raindrops. Effective pressure was 1.4 Pa for the artificial rain by sprinkler machine «Fregat» and 5.9 Pa for long distance sprinkler DD-30. The article deals with a block diagram of the sequence for determining the effective pressure of rain drops on the soil. This diagram was created by the author’s method of calculation of the effective pressure of rain drops on the soil. The need for an integrated approach to the description of the artificial rain impact on the soil is noted. Various parameters characterizing drop erosion are considered. There are data about the mass of splashed soil in the irrigation of various irrigation machinery and installations. For example, the rate (mass) of splashed soil was 0.28…0.78 t/ha under irrigation sprinkler apparatus RACO 4260–55/701C in the conditions of the Ryazan region. The method allows examining the environmental impact of sprinkler techniques for analyzes of the pressure, caused by raindrops, on the soil. It can also be useful in determining the irrigation rate before the runoff for different types of sprinkler equipment and soil conditions.


2015 ◽  
Vol 42 (12) ◽  
pp. 1071-1089
Author(s):  
Alan Chan ◽  
Bruce G. Fawcett ◽  
Shu-Kam Lee

Purpose – Church giving and attendance are two important indicators of church health and performance. In the literature, they are usually understood to be simultaneously determined. The purpose of this paper is to estimate if there a sustainable church congregation size using Wintrobe’s (1998) dictatorship model. The authors want to examine the impact of youth and adult ministry as well. Design/methodology/approach – Using the data collected from among Canadian Baptist churches in Eastern Canada, this study investigates the factors affecting the level of the two indicators by the panel-instrumental variable technique. Applying Wintrobe’s (1998) political economy model on dictatorship, the equilibrium level of worship attendance and giving is predicted. Findings – Through various simulation exercises, the actual church congregation sizes is approximately 50 percent of the predicted value, implying inefficiency and misallocation of church resources. The paper concludes with insights on effective ways church leaders can allocate scarce resources to promote growth within churches. Originality/value – The authors are the only researchers getting the permission from the Atlantic Canada Baptist Convention to use their mega data set on church giving and congregation sizes as per the authors’ knowledge. The authors are also applying a theoretical model on dictatorship to religious/not for profits organizations.


2014 ◽  
Vol 44 (7) ◽  
pp. 777-783 ◽  
Author(s):  
Jillian Kaufmann ◽  
Edward W. Bork ◽  
Michael J. Alexander ◽  
Peter V. Blenis

The impact of summer cattle grazing on deciduous tree regeneration within uncut forests, clearcuts, partially harvested areas, and in-block haul road habitats was examined in four experimental pastures of central Alberta during 2008 and 2009. Sampling of 233 field plots, both inside and outside cattle exclosures, was used to document sapling densities, height, and type of damage. Tree densities (primarily aspen (Populus tremuloides Michx.)) differed among habitats but less so with exposure to cattle. Densities were greatest in clearcuts, followed by partially harvested areas and then uncut forest and haul roads. While exposure to cattle reduced total tree regeneration, sapling densities and sizes remained sufficient to meet postharvest standards for deciduous forest regeneration in Alberta, even with exposure to cattle. Cattle damage in harvested areas was primarily from browsing (≤3.2% of saplings), with proportionally more trees affected in uncut forests (8.6%). Browsing was particularly high on balsam poplar (Populus balsamifera L.) (25%) during 2008. Although sapling damage increased with high cattle stocking in 2008 (to 10.5%), total mortality was limited to 15.5% through 2009. These findings show that despite cattle impacts to some saplings, damage levels were insufficient to alter deciduous regeneration, highlighting the compatibility of cattle grazing and sustainable forest management on public lands in this region.


Oecologia ◽  
2021 ◽  
Author(s):  
Sophia G. Lavergne ◽  
Charles J. Krebs ◽  
Alice J. Kenney ◽  
Stan Boutin ◽  
Dennis Murray ◽  
...  

2008 ◽  
Vol 16 (NA) ◽  
pp. 157-179 ◽  
Author(s):  
David P. Kreutzweiser ◽  
Paul W. Hazlett ◽  
John M. Gunn

Logging disturbances in boreal forest watersheds can alter biogeochemical processes in soils by changing forest composition, plant uptake rates, soil conditions, moisture and temperature regimes, soil microbial activity, and water fluxes. In general, these changes have often led to short-term increases in soil nutrient availability followed by increased mobility and losses by leaching to receiving waters. Among the studies we reviewed, dissolved organic carbon (DOC) exports usually increased after logging, and nitrogen (N) mineralization and nitrification often increased with resulting increased N availability and exports to receiving waters. Similar processes and responses occurred for phosphorus (P), but to a lesser extent than for N. In most cases, base cations were released and exported to receiving waters after logging. Several studies demonstrated that stem-only or partial-harvest logging reduced the impacts on nutrient release and exports in comparison to whole-tree clear-cutting. Despite these logging-induced increases in soil nutrient availability and movement to receiving waters, most studies reported little or no change in soil chemical properties. However, responses to logging were highly variable and often site specific. The likelihood, extent and magnitude of logging impacts on soil nutrient cycling and exports in boreal forest watersheds will be dependent on soil types, stand and site conditions, hydrological connectivity, post-logging weather patterns, and type and timing of harvest activities. Additionally, logging impacts can interact with, and be confounded by, atmospheric pollutant deposition and climate change. Further watershed-level empirical studies and modeling efforts are required to elucidate these interactions, to improve predictive capabilities, and to advance forest management guidelines for sustaining forest soil productivity and limiting nutrient exports.


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