scholarly journals A Comparison of some Upland and Valley Soils in the Ungava-Labrador Peninsula

2007 ◽  
Vol 38 (3) ◽  
pp. 243-256 ◽  
Author(s):  
William H. Hendershot

ABSTRACT Thirteen soil profiles from northern Québec and Labrador, Canada, near the northern tree-line, were sampled and analysed. Five of these, located on poorly to imperfectly drained sites, are strongly cryoturbated soils with permafrost at a shallow depth. Below the surface horizon they have very uniform profile distributions of pH, carbon and extractable iron and aluminum due to the active mixing of the horizons. The eight soils from well-drained sites have profiles similar to those of soils in similar settings in more temperate climatic regions. One of these, developed in one of the most northerly valleys having a black spruce-larch forest vegetation, has the characteristics of a podzol (spodosol) except that the podzolic B (spodic) horizon is too thin. The other seven profiles all have color B horizons, although the coarse texture prevents their classification as cambic horizons; these soils all have carbon-rich A horizons varying in thickness from 1.5 to 20 cm. Soil temperature at 50 cm depth closely follows the elevational and latitudinal distribution of the soils; a range of 0 to 10° C was observed. Soil development, measured as depth of solum, organic carbon accumulation or degree of B horizon development, is closely related to soil temperature and site position. The presence of permanently frozen ice layers at shallow depth has a marked influence on soil genesis and the properties of the resultant soils.

2021 ◽  
Vol 19 (1) ◽  
pp. e1102
Author(s):  
Maroua Dachraoui ◽  
Aurora Sombrero

Aim of study: To evaluate the effects of conventional tillage (CT) and no tillage (NT) systems on the soil organic carbon (SOC) changes, CO2 emissions and their relation with soil temperature and grain yield in a monoculture of irrigated maize during six years.Area of study: In Zamadueñas experimental field in the Spanish province of Valladolid, from 2011 to 2017.Material and methods: The SOC content was determined by collecting soil samples up to 30 cm in November at two years interval. Short-term CO2 emissions were measured simultaneously with soil temperature using a respiration chamber and a hand-held probe immediately before, after every tillage operation and during the maize cycle.Main results: The SOC stock of the top 30 cm soil layers was 13% greater under NT than CT. Short-term CO2 emissions were significantly higher under CT ranging from 0.8 to 3.4 g CO2 m-2 h-1 immediately after tillage while under NT system, soil CO2 fluxes were low and stable during this study period. During the first 48 h following tillage, cumulative CO2 emissions ranged from 0.6 to 2.4 Mg CO2 ha-1 and from 0.2 to 0.3 Mg CO2 ha-1 under CT and NT systems, respectively. Soil temperature did not show significant correlation with CO2 emissions; however, it depended mostly on the time of measurement.Research highlights: No tillage increased the SOC accumulation in the topsoil layer, reduced CO2 emissions without decreasing maize grain yield and minimized the impact on climate change compared to CT system.


1996 ◽  
Vol 74 (5) ◽  
pp. 686-693 ◽  
Author(s):  
Simon M. Landhäusser ◽  
Ross W. Wein ◽  
Petra Lange

Low soil temperatures and water availability are thought to be major factors determining the distribution of tree species at the arctic tree line. A comparative study examined the response of Betula papyrifera, Populus balsamifera, and Picea mariana seedlings to different soil temperatures and drought regimes in a growth chamber experiment. Morphological and ecophysiological responses (net assimilation rate, stomatal conductance to water vapour, and residual conductance) of these tree line tree species were measured and compared. Mean biomass accumulation of the deciduous species was greater than that of Picea mariana with increasing soil temperatures. Root biomass showed an increase of 30% in the three species between the soil temperatures of 3 and 15 °C. Response of ecophysiological variables to increased soil temperature was greater in B. papyrifera and Populus balsamifera than in Picea mariana. In a second experiment, drought-preconditioned B. papyrifera and Populus balsamifera seedlings were subjected to a 6-day water-withholding treatment. Drought decreased shoot mass and increased the root to shoot ratio equally in B. papyrifera and Populus balsamifera. Drought-preconditioned B. papyrifera and Populus balsamifera seedlings responded differently to the 6-day water-withholding treatment. Betula papyrifera used a water-conserving strategy and maintained low net assimilation rates and low water use after drought preconditioning, whereas in Populus balsamifera greater net assimilation rates were associated with drought preconditioning. These results are consistent with the distribution of these three tree species at the arctic tree line. Keywords: Picea mariana, Populus balsamifera, Betula papyrifera, drought preconditioning, soil temperature, arctic tree line.


2020 ◽  
Vol 10 (3) ◽  
pp. 1058
Author(s):  
Keunbo Park ◽  
Yongwon Kim ◽  
Kichoel Lee ◽  
Dongwook Kim

A model for predicting shallow depth soil temperatures is important and effective to assess the changes in soil conditions related to global climate change and local disturbances. Shallow-depth soil temperature estimation model in cold region in Alaska is developed based on thermal response using air temperature and shallow-depth soil water content during active layer development period of 160 days from May to October. Among the seven soil temperature measurement sites, data from four sites were used for model development, and the remaining three sites were used for model validation. Near the middle of the seven measurement sites, air temperature is monitored at one location. The proposed model implemented concepts of thermal response and cumulative temperature. Temperatures and soil water contents were measured using automated remote sensing technology. Consequently, it was confirmed that the developed model enables fast and accurate assessment of shallow-depth soil temperature during active soil layer development period.


2005 ◽  
Vol 35 (9) ◽  
pp. 2073-2081 ◽  
Author(s):  
Andrea H Lloyd ◽  
Alexis E Wilson ◽  
Christopher L Fastie ◽  
R Matthew Landis

Black spruce (Picea mariana (Mill.) BSP) is the dominant species in interior Alaska but it is largely absent from the arctic tree line. To evaluate the importance of climate and fire as controls over the species distribution, we reconstructed stand history at three sites near its northern limit in Alaska, where it grows with white spruce (Picea glauca (Moench) Voss). We developed a matrix model to explore black spruce population dynamics and response to varying fire intervals. All sites burned in the early 1900s. High recruitment of black spruce occurred for <30 years following the fire, but most current black spruce recruitment is clonal and seed viability is low. White spruce recruitment has been consistently high since the fire, and the majority of seedlings in the stands are white spruce. Despite low recruitment, the matrix model suggests that black spruce populations are nearly stable, largely because of low adult mortality rates. Although black spruce recruitment is stimulated by fire, the model indicates that fire intervals <350 years would destabilize the population, primarily because of slow growth and low seed production. Population dynamics of black spruce at its northern limit in Alaska thus appear to reflect an interaction between fire, which determines the temporal pattern of tree recruitment, and climate, which limits tree growth and, presumably, viable seed production.


2011 ◽  
Vol 32 (1) ◽  
pp. 74-82 ◽  
Author(s):  
C. Lupi ◽  
H. Morin ◽  
A. Deslauriers ◽  
S. Rossi

1983 ◽  
Vol 99 (1) ◽  
pp. 44-47 ◽  
Author(s):  
F. H. W. Green
Keyword(s):  

1983 ◽  
Vol 13 (5) ◽  
pp. 747-766 ◽  
Author(s):  
Keith Van Cleve ◽  
Lola Oliver ◽  
Robert Schlentner ◽  
Leslie A. Viereck ◽  
C. T. Dyrness

This paper considers the productivity and nutrient cycling in examples of the major forest types in interior Alaska. These ecosystem properties are examined from the standpoint of the control exerted over them by soil temperature and forest-floor chemistry. We conclude that black spruce Piceamariana (Mill.) B.S.P. occupies the coldest, wettest sites which support tree growth in interior Alaska. Average seasonal heat sums (1132 ± 32 degree days (DD)) for all other forest types were significantly higher than those encountered for black spruce (640 ± 40 DD). In addition, black spruce ecosystems display the highest average seasonal forest-floor and mineral-soil moisture contents. Forest-floor chemistry interacts with soil temperature in black spruce to produce the most decay-resistant organic matter. In black spruce the material is characterized by the highest lignin content and widest C/N (44) and C/P (404) ratios. Across the range of forest types examined in this study, soil temperature is strongly related to net annual aboveground tree production and the annual tree requirement for N, P, K, Ca, and Mg. Forest floor C/N and C/P ratios are strongly related to annual tree N and P requirement and the C/N ratio to annual tree production. In all cases these controls act to produce, in black spruce, the smallest accumulation of tree biomass, standing crop of elements, annual production, and element requirement in aboveground tree components.


2012 ◽  
Vol 9 (1) ◽  
pp. 1129-1159 ◽  
Author(s):  
Y. Kim ◽  
Y. Kodama

Abstract. Winter CO2 flux is an important element to assess when estimating the annual carbon budget on regional and global scales. However, winter observation frequency is limited due to the extreme cold weather in sub-Arctic and Arctic ecosystems. In this study, the continuous monitoring of winter CO2 flux in black spruce forest soil of interior Alaska was performed using NDIR CO2 sensors at 10, 20, and 30 cm above the soil surface during the snow-covered period (DOY 357 to 466) of 2006/2007. The atmospheric pressure was divided into four phases: >1000 hPa (HP: high pressure); 985<P<1000 (IP: intermediate pressure); <986 hPa (LP: low pressure); and a snow-melting period (MP); for the quantification of the effect of the environmental factors determining winter CO2 flux. The winter CO2 fluxes were 0.22 ± 0.02, 0.23 ± 0.02, 0.25 ± 0.03, and 0.17 ± 0.02 gCO2-C/m2 d−1 for the HP, IP, LP, and MP phases, respectively. Wintertime CO2 emission represents 20 % of the annual CO2 emissions in this boreal black spruce forest soil. Atmospheric temperature, pressure, and soil temperature correlate at levels of 56, 25, and 31 % to winter CO2 flux, respectively, during the snow-covered period of 2006/2007, when snow depth experienced one of its lowest totals of the past 80 years. Atmospheric temperature and soil temperature at 5 cm depth, modulated by atmospheric pressure, were found to be significant factors in determining winter CO2 emission and fluctuation in snowpack. Regional/global process-based carbon cycle models should be reassessed to account for the effect of winter CO2 emissions, regulated by temperature and soil latent-heat flux, in the snow-covered soils of Arctic and sub-Arctic terrestrial ecosystems of the Northern Hemisphere.


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