Recovery of 15N-labelled nitrate applied to a small upland boreal forest catchment

2000 ◽  
Vol 30 (7) ◽  
pp. 1165-1177 ◽  
Author(s):  
Sébastien Lamontagne ◽  
Sherry L Schiff ◽  
Richard J Elgood
Keyword(s):  
Boreal Forest ◽  
Pinus Banksiana ◽  
Mineral Soil ◽  
N Recovery ◽  
Short Term ◽  
Organic Horizons ◽  
Balance Analysis ◽  
Second Year ◽  
Forest Island ◽  
Forest Islands

Nitrate labelled with 15N was added for 2 years to a small Boreal Shield forested catchment to evaluate where new nitrogen (N) inputs are stored in this system in the short term. The landscape in the study catchment is a mosaic of Pinus banksiana Lamb. - Picea mariana (Mill.) BSP "forest islands" surrounded by "pillows" of lichens, mosses, and grasses on exposed bedrock surfaces. After the second year of N addition, 10% of the added 15N was found in aboveground biomass, 27% in organic horizons, 6% in forest island mineral soil, 3% in "soil" underneath pillows, and 16% was lost through runoff. Despite covering a smaller proportion of the catchment and having only slightly larger N stocks, forest islands stored more 15N (31%) than pillows (15%). Preferential routing of water towards forest islands and a greater potential for biotic and abiotic N immobilization are hypothesized to favor N retention in forest islands. Thirty-eight percent of the 15N could not be accounted for. The comparison of a mass-balance analysis with the 15N recovery suggests a missing sink for the 15N in forest islands, possibly woody detritus. In the short term (~2 years), organic horizons are the main sinks for elevated N inputs in the boreal forest.

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.

Seed banks in five boreal forest stands originating between 1810 and 1963

1982 ◽  
Vol 60 (9) ◽  
pp. 1815-1821 ◽  
Author(s):  
Anders Granström
Keyword(s):  
Boreal Forest ◽  
Plant Species ◽  
Mineral Soil ◽  
Coniferous Forest ◽  
Soil Samples ◽  
Distribution Data ◽  
Forest Stands ◽  
Humus Layer ◽  
Seed Content ◽  
Organic Horizons

The viable seed content of soil samples from five coniferous forest stands in northern Sweden, aged 16–169 years, was determined by means of germination trials. The soil samples were separated into five fractions: three organic horizons and two mineral soil horizons. Seedlings of 15 phanerogam species emerged, representing densities of 239–763 seeds/m2 in the soils from the different stands. The depth distributions of the seeds varied with both plant species and forest stand. Most seeds were found at various depths in the humus layer, but in one stand an appreciable seed density of Luzula pilosa was present in the mineral soil. Most of the seedlings belonged to plant species present in the vegetation or with good means of dispersal. The depth distribution data, however, suggest that Luzula pilosa in particular may have a persistent seed bank. The role of persistent seeds in the vegetational composition of the boreal forest is discussed.

Recruitment of Picea mariana, Pinus banksiana, and Populus tremuloides across a burn severity gradient following wildfire in the southern boreal forest of Quebec

2004 ◽  
Vol 34 (9) ◽  
pp. 1845-1857 ◽  
Author(s):  
D F Greene ◽  
J Noël ◽  
Y Bergeron ◽  
M Rousseau ◽  
S Gauthier
Keyword(s):  
Boreal Forest ◽  
Populus Tremuloides ◽  
Pinus Banksiana ◽  
Fire Severity ◽  
Mineral Soil ◽  
Basal Area ◽  
Published Data ◽  
Crown Fire ◽  
Conifer Species ◽  
Seed Supply

Most studies of postfire tree recruitment have occurred in severely burned portions, despite the fact that partial burning is common. In this study we examined regeneration following a 1997 fire in the boreal forest of Quebec. A model of postfire recruitment was elaborated using parameters such as the proportion of trees killed (severity), the proportions of postfire seedbed types and their associated juvenile survivorship, the available seed supply, the available bud supply (for Populus tremuloides Michx.), and the granivory rate. All three species had peak recruitment in the first or second summer, and the recruitment episode was essentially finished after the third year. Mineral soil and surviving Sphagnum were the best seedbeds for both conifer species. Seedbed frequency was essentially independent of crown fire severity except for surviving Sphagnum, which was concentrated primarily where severity was light. Conifer fecundity was much lower in the lightly burned stands, a result we attribute to a higher granivory rate. The fecundity (seedlings/basal area for the conifers or suckers/basal area for Populus) in the severe sites was typical of the few other North American studies of postfire recruitment, where the published data permit us to make the comparison.

Spatiotemporal evolution of paludification associated with autogenic and allogenic factors in the black spruce–moss boreal forest of Québec, Canada

2019 ◽  
Vol 91 (2) ◽  
pp. 650-664 ◽  
Author(s):  
Éloïse Le Stum-Boivin ◽  
Gabriel Magnan ◽  
Michelle Garneau ◽  
Nicole J. Fenton ◽  
Pierre Grondin ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Vegetation Dynamics ◽  
Pinus Banksiana ◽  
Fire History ◽  
Black Spruce ◽  
Mineral Soil ◽  
Abies Balsamea ◽  
Organic Layer ◽  
Coniferous Species ◽  
Topographic Depressions

AbstractPaludification is the most common process of peatland formation in boreal regions. In this study, we investigated the autogenic (e.g., topography) and allogenic (fire and climate) factors triggering paludification in different geomorphological contexts (glaciolacustrine silty-clayey and fluvioglacial deposits) within the Québec black spruce (Picea mariana)–moss boreal forest. Paleoecological analyses were conducted along three toposequences varying from a forest on mineral soil to forested and semi-open peatlands. Plant macrofossil and charcoal analyses were performed on basal peat sections (≤50 cm) and thick forest humus (<40 cm) to reconstruct local vegetation dynamics and fire history involved in the paludification process. Results show that primary paludification started in small topographic depressions after land emergence ca. 8000 cal yr BP within rich fens. Lateral peatland expansion and secondary paludification into adjacent forests occurred between ca. 5100 and 2300 cal yr BP and resulted from low-severity fires during a climatic deterioration. Fires that reduced or eliminated entirely the organic layer promoted the establishment ofSphagnumin microdepressions. Paludification resulted in the decline of some coniferous species such asAbies balsameaandPinus banksiana. The paleoecological approach along toposequences allowed us to understand the spatiotemporal dynamics of paludification and its impacts on the vegetation dynamics over the Holocene.

Short-term fate of atmospherically deposited nitrogen in temperate forest under warming

2020 ◽  
Author(s):  
Yihang Duan ◽  
Yunting Fang
Keyword(s):  
Global Warming ◽  
Nitrogen Deposition ◽  
Temperate Forest ◽  
Forest Ecosystems ◽  
Mineral Soil ◽  
Soil Layer ◽  
N Recovery ◽  
Short Term ◽  
N Retention ◽  
And Control

&lt;p&gt;Anthropogenic activities have notably disturbed the natural carbon and nitrogen cycle since the industry revolution. The consequential results include a warmer climate and enhanced nitrogen deposition on forest ecosystems. Covering one-third of the landmass, forests possess vital ecosystem functions such as N retention and the resulting C sequestration. However, the ongoing changes in climate and nitrogen deposition could potentially alter these important processes. Therefore, measures need to be taken to assess the distribution of deposited N in warming forest ecosystems. Here, we use &lt;sup&gt;15&lt;/sup&gt;N tracer method to investigate the short-term (2 weeks, 1 month and 3 months) fate of deposited N in a temperate forest, and by taking advantage of the in situ infrared heating, we also attempt to explore the effect of warming ( 2 &amp;#176;C ) on deposited N in forest ecosystems. The results showed that deposited N was largely retained by litter in all treatments (38%-57%) and mineral soil layers contained the least nitrogen. Total&amp;#160;&lt;sup&gt;15&lt;/sup&gt;N recovery of different ecosystem compartments between warmed and control treatments showed distinct pattern, recovery in warming treatment increased from 72% to 97% after 1 month while the respect recovery of control treatment gradually decreased with time. In the top mineral soil layer (0-10cm), control treatments had higher recovery than warming treatment, suggesting warming may hinder deposited N from forging downwards, however, higher &amp;#948;&lt;sup&gt;15&lt;/sup&gt;N value in top mineral soil layer suggesting enhanced microbial activities maybe in action. Little leaching loss of deposited N both in warm and control was observed. Difference in deposited N fate between warming and control could deepen our understanding of how global warming influence forest ecosystem processes, particularly the N cycle.&lt;/p&gt;&lt;p&gt;Key words: Soil warming; &lt;sup&gt;15&lt;/sup&gt;N tracer; N deposition; N retention and redistribution; Global warming; Temperate forest&lt;/p&gt;

Evaluation of Visuospatial Short-term and Working Memory from the First to Second Year of Life: A Novel Task

2021 ◽  
pp. 1-17
Author(s):  
C. Fernandez-Baizan ◽  
Miguel Angel Prieto ◽  
J. A. Martinez ◽  
J. L. Arias ◽  
M. Mendez
Keyword(s):  
Working Memory ◽  
Short Term ◽  
Second Year Of Life ◽  
Second Year

Silvicultural treatments, microclimatic conditions and seedling response in Southern Interior clearcuts

1998 ◽  
Vol 78 (1) ◽  
pp. 115-126 ◽  
Author(s):  
R. L. Fleming ◽  
T. A. Black ◽  
R. S. Adams ◽  
R. J. Stathers
Keyword(s):  
Soil Moisture ◽  
Seedling Establishment ◽  
Initial Period ◽  
Mineral Soil ◽  
Soil Disturbance ◽  
Near Surface ◽  
Lower Elevation ◽  
Organic Horizons ◽  
Soil Temperatures ◽  
Microclimatic Conditions

Post-harvest levels of soil disturbance and vegetation regrowth strongly influence microclimate conditions, and this has important implications for seedling establishment. We examined the effects of blading (scalping), soil loosening (ripping) and vegetation control (herbicide), as well as no soil disturbance, on growing season microclimates and 3-yr seedling response on two grass-dominated clearcuts at different elevations in the Southern Interior of British Columbia. Warmer soil temperatures were obtained by removing surface organic horizons. Ripping produced somewhat higher soil temperatures than scalping at the drier, lower-elevation site, but slightly reduced soil temperatures at the wetter, higher-elevation site. Near-surface air temperatures were more extreme (higher daily maximums and lower daily minimums) over the control than over exposed mineral soil. Root zone soil moisture deficits largely reflected transpiration by competing vegetation; vegetation removal was effective in improving soil moisture availability at the lower elevation site, but unnecessary from this perspective at the higher elevation site. The exposed mineral surfaces self-mulched and conserved soil moisture after an initial period of high evaporation. Ripping and scalping resulted in somewhat lower near-surface available soil water storage capacities. Seedling establishment on both clearcuts was better following treatments which removed vegetation and surface organic horizons and thus enhanced microclimatic conditions, despite reducing nutrient supply. Such treatments may, however, compromise subsequent stand development through negative impacts on site nutrition. Temporal changes in the relative importance of different physical (microclimate) and chemical (soil nutrition) properties to soil processes and plant growth need to be considered when evaluating site productivity. Key words: Microclimate, soil temperature, air temperature, soil moisture, clearcut, seedling establishment

Influence of sampling date and substrate on nitrogen mineralization: comparison of laboratory-incubation and buried-bag methods for two Massachusetts forest soils

1992 ◽  
Vol 22 (12) ◽  
pp. 1895-1900 ◽  
Author(s):  
Richard D. Boone
Keyword(s):  
Organic Matter ◽  
N Mineralization ◽  
Unit Area ◽  
Seasonal Pattern ◽  
Mineral Soil ◽  
Net N Mineralization ◽  
Laboratory Incubation ◽  
Mineralization Potential ◽  
Organic Horizons ◽  
N Mineralization Potential

Nitrogen (N) mineralization potential and net N mineralization insitu were measured monthly over 7 months for the forest floor horizons (Oi, Oe, Oa) and mineral soil (0–15 cm) of a pine stand and the mineral soil (0–15 cm) of a maple stand in Massachusetts, United States. In all cases, N mineralization potential per unit organic matter (anaerobic laboratory incubation) varied significantly by sampling month but was unrelated to the seasonal pattern for net N mineralization (buried-bag method). The organic horizons in the pine stand exhibited the most variable N mineralization potential, with the Oe horizon having more than a fourfold seasonal range. For the pine stand the Oe horizon also had the highest N mineralization potential (per unit organic matter) and the highest net N mineralization insitu (per unit area). In general, temporal and depth-wise variability should be considered when sites are assessed with respect to the pool of mineralizable N.

Responses of boreal conifers to climate fluctuations: indications from tree-ring widths and carbon isotope analyses

1998 ◽  
Vol 28 (4) ◽  
pp. 524-533 ◽  
Author(s):  
J Renée Brooks ◽  
Lawrence B Flanagan ◽  
James R Ehleringer
Keyword(s):  
Climate Change ◽  
Boreal Forest ◽  
Carbon Isotope ◽  
Tree Ring ◽  
Picea Mariana ◽  
Pinus Banksiana ◽  
Annual Growth ◽  
Climate Change Scenarios ◽  
Southern Boundary ◽  
The North

Spatial distribution and species composition of the boreal forest are expected to change under predicted climate change scenarios. Current research indicates that water limitations control the southern boundary of the central Canadian boreal forest and temperature limitations control the northern boundary. As part of Boreal Ecosystem - Atmosphere Study (BOREAS), we examined this idea by comparing annual variation in tree-ring widths and carbon isotope ratios ( delta 13C) of tree-ring cellulose with annual climatic parameters in the northern and southern boreal forest. Contrary to expectations, climate correlations with ring widths at the northern and southern sites were similar in black spruce (Picea mariana (Mill.) BSP). Annual growth was favored by cooler and wetter conditions. For jack pine (Pinus banksiana Lamb.), increased temperature and spring precipitation favored annual growth at both sites. In the north, annual growth was negatively correlated with winter precipitation. The delta 13C - climate correlations in Pinus banksiana followed current distribution theories. In the south, potential evapotranspiration explained significant annual delta 13C variation, whereas in the north, winter and growing season precipitation influenced annual delta 13C variations. Our data support the concept that moisture limits the southern range of Pinus banksiana and cold soil temperatures limit the northern extent. However, colder, wetter conditions favored growth of Picea mariana throughout its range. These observations strengthen the concept that species respond individually to climate change, not as a cohesive biome.

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