Gas Diffusivity in the Forest Humus Layer

Soil Science ◽  
2019 ◽  
Vol 184 (1) ◽  
pp. 13-16 ◽  
Author(s):  
Martin Maier ◽  
Verena Lang
Keyword(s):  
Gas Diffusivity ◽  
Humus Layer ◽  
Forest Humus

scholarly journals On the Composition of Forest Humus Layer (H Layer.)

1942 ◽  
Vol 18 (9) ◽  
pp. 866-868
Author(s):  
R. KAWASHIMA ◽  
M. NAGATA ◽  
G. SUYAMA
Keyword(s):  
Humus Layer ◽  
Forest Humus

Effects of liming on soil structure and GHG fluxes at three spruce sites in SW Germany

2021 ◽  
Author(s):  
Martin Maier ◽  
Valentin Gartiser ◽  
Verena Lang ◽  
Raphael Habel ◽  
Lelde Jansone ◽  
...  
Keyword(s):  
Soil Ph ◽  
Forest Soils ◽  
Soil Structure ◽  
Pore Space ◽  
Mineral Soil ◽  
Soil Gas ◽  
Long Term Effects ◽  
Gas Diffusivity ◽  
Humus Layer

<p>Forest soils in Central Europe received massive atmospheric deposition of SO<sub>2</sub> and NO<sub>x</sub> during the second half of the 20<sup>th</sup> century. The resulting fast acidification of the soils was accompanied by massive forest dieback and problematic nutrient imbalances at some sites. After the emissions of SO<sub>2</sub> have been reduced in the 80´s and 90´s, the situation of acidic deposition has been gradually improving. Yet, the deposition of N compounds remains high and still has an impact on forest ecosystems. Natural soil development and “regeneration” is a slow process, which is why other options were investigated to recover heavily affected forest soils. A well-known means to mitigate the observed effects of the anthropogenic acidification surges is liming, i.e. the application of minerals such as CaCO<sub>3</sub> and CaMg(CO<sub>3</sub>)<sub>2</sub> that are able to buffer strong acids. Liming directly affects soil pH which is a “master variable” of the soil. Soil pH, and thus, liming, affects and interacts with many soil processes from mineralization of organic matter and humification, to (de-) stabilization soil structure, nutrient availability and mobility, plant growth and more.</p><p>Several study sites were established in the 1980 in Baden-Wuerttemberg to study long term effects of liming on soil structure and forest growth. At all sites a “control” plot and a “limed” plot were established next to each other. The limed plots were treated with approx. 3 t ha<sup>-1</sup> of CaCO<sub>3</sub> in the 1980´s and 6 t ha<sup>-1</sup> of Ca/MgCO<sub>3 </sub>in 2003. Here we report on results from three sites (Bad Waldsee, Hospital, Herzogenweiler) with Spruce stands (70-110 years), where long term effects of liming on the physical soil structure and soil gas profiles (2017-2019) were studied (Jansone et al., 2020). Liming resulted in a reduction of the thickness of the humus layer and a blurring of the previously clearly separated boundary between the mineral soil and the humus layer. Even though total pore space in the top soil was slightly reduced at the limed plots, soil gas diffusivity was higher at a given air-filled pore-space. This indicates a better connectivity in the air-filled pores, that means more larger pores connecting the atmosphere at the soil surface and the mineral soil. Soil CO<sub>2</sub> concentrations showed clear seasonal patterns and a typical increase with depth. Higher CO<sub>2</sub> concentrations tend to be found in the un-limed control plots. Soil CH<sub>4</sub> concentrations at the soil–humus interface were closer to atmospheric concentrations in the limed plots compared to the control plots. This can be interpreted as an effect of the decrease in the thickness of the humus layer and the increase in the soil gas diffusivity (better aeration) or in a reduced activity of the methanotrophic community.</p><p> </p><p>Acknowledgement</p><p>This research was financially supported by Bundesministerium für Ernährung und Landwirtschaft (BMEL), grant number 28W-B-4-075-02 (2018–2021).</p><p><em>Literature</em></p><p><em>Jansone, L., von Wilpert, K. and Hartmann, P., 2020. Natural Recovery and Liming Effects in Acidified Forest Soils in SW-Germany. Soil Systems, 4(38): 1-35.</em></p>

Silvicultural characteristics of a Scots pine stand on drift sands

1992 ◽  
Vol 57 ◽  
Author(s):  
D. Maddelein ◽  
N. Lust
Keyword(s):  
Scots Pine ◽  
Mixed Forest ◽  
Rotation Period ◽  
Average Height ◽  
Indigenous Species ◽  
Pedunculate Oak ◽  
Black Cherry ◽  
Humus Layer ◽  
Pine Seedlings ◽  
Pine Regeneration

The  study of a seventy years old stand of Scots pine on drift sands proves that  Scots pine growth on these sites was and is still relatively good: average  diameter 27.6 cm, average height 19.4 m, standing volume 213 m3 and an annual increment  of 4.9 m3.ha-1.yr-1. All Scots pines  belong to the upper storey. Yet considerable differences in crown development  and vitality are observed. The current growth rate and the spontaneous  settlement of pine seedlings under canopy show the ideal conditions for the  creation of a high forest with reserves. Anyway a rotation period of more  than 70 years is recommendable.     On several places a consolidated regeneration of Scots pine seedlings under  canopy occur. Groups with a stem number of 700 to 3,500 seedlings per are, ranging  in age from 3 to 11 years and in height from 10 to 170 cm, are present. This  Scots pine regeneration has developed in a normal mor humus layer and in a  dense Deschampsia mat.      Broadleaved regeneration is not so abundant, and consists for 75 % of black  cherry. Absence of seed trees, browsing damage and the exclusive character of  black cherry are the limiting factors for the installation and survival of  valuable indigenous species, such as pedunculate oak.     Provided that black cherry is removed and that the regeneration is  protected against wild damage, it is possible to create a mixed forest  dominated by Scots pine but with a considerable admixture of indigenous  broadleaved trees. However, if black cherry will not be sufficiently  controlled, it can be expected that in a first phase black cherry will  dominate the understorey, that it will prevent the regeneration of all other  species and that, very soon, it will form an almost single-species dominated  stage in forest succession.

Monitoring of natural regeneration in a mixed deciduous forest

1999 ◽  
Vol 64 ◽  
Author(s):  
K. M. Tabari ◽  
N. Lust
Keyword(s):  
Survival Rate ◽  
Natural Regeneration ◽  
Deciduous Forest ◽  
Seedling Stage ◽  
Permanent Plots ◽  
Soil Conditions ◽  
Growing Seasons ◽  
Humus Layer ◽  
Beech Stand ◽  
Regeneration Phase

Monitoring  of natural regeneration in a dense semi-natural mixed hardwood forest on the  base    of ash, beech, oak and sycamore occurred over 3 years in the Aelmoeseneie  experimental    forest, Belgium. 40 permanent plots (4 m x 5 m) were selected in three  various humus types,    located in an ash stand and in an oak - beech stand. In all plots abundance  and top height of all    broad leaved regenerated species were determined at the end of the growing  seasons 1995 and    1998. In addition, the seedlings which appeared in the plots during 1996  and 1997 were    identified and followed up.    This study proves that in the investigated sites natural regeneration is  drastically poor and    diversity is low, in particular where the humus layer is more acidic (mull  moder) and the litter    layer is thick. No regeneration phase older than the seedling stage (h <  40 cm) is developed on    the different humus types. On average, total number of seedlings in 1995  amounts to 38    units/are in the ash stand and to 63 units/are in the oak - beech stand.  Survival rate over a 3-    year period is 37% and 42% respectively in the ash and oak - beech stands.  Total ingrowth    during the growing seasons 1996 and 1997 is virtually poor, indicating 16  and 8 units/are    respectively in above mentioned stands. Survival rate of occurring  seedlings, as well as the ingrowth of new seedlings are notably different (P < 0.05) according to the soil conditions of the    ash stand. Generally, the low presence of seedlings and the lack of  regeneration older than the    seedling stage reveal that the regeneration development encounters with a  critical problem. The    continuation of this process would likely result in a progressive  succession by the invasive and    the unwanted tree species.

scholarly journals Irrigation Scheduling with Soil Gas Diffusivity as a Decision Tool to Mitigate N2O Emissions from a Urine-Affected Pasture

Agriculture ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 443
Author(s):  
Camille Rousset ◽  
Timothy J. Clough ◽  
Peter R. Grace ◽  
David W. Rowlings ◽  
Clemens Scheer
Keyword(s):  
Irrigation Management ◽  
Irrigation Treatment ◽  
Irrigation Scheduling ◽  
Soil Gas ◽  
N2o Emissions ◽  
Irrigation Frequency ◽  
Water Demands ◽  
Gas Diffusivity ◽  
Matter Production ◽  
Access To Water

Pastures require year-round access to water and in some locations rely on irrigation during dry periods. Currently, there is a dearth of knowledge about the potential for using irrigation to mitigate N2O emissions. This study aimed to mitigate N2O losses from intensely managed pastures by adjusting irrigation frequency using soil gas diffusivity (Dp/Do) thresholds. Two irrigation regimes were compared; a standard irrigation treatment based on farmer practice (15 mm applied every 3 days) versus an optimised irrigation treatment where irrigation was applied when soil Dp/Do was ≈0.033 (equivalent to 50% of plant available water). Cow urine was applied at a rate of 700 kg N ha−1 to simulate a ruminant urine deposition event. In addition to N2O fluxes, soil moisture content was monitored hourly, Dp/Do was modelled, and pasture dry matter production was measured. Standard irrigation practices resulted in higher (p = 0.09) cumulative N2O emissions than the optimised irrigation treatment. Pasture growth rates under treatments did not differ. Denitrification during re-wetting events (irrigation and rain) contributed to soil N2O emissions. These results warrant further modelling of irrigation management as a mitigation option for N2O emissions from pasture soils, based on Dp/Do thresholds, rainfall, plant water demands and evapotranspiration.

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