scholarly journals Different soil moisture control of net methane oxidation and production in organic upland and wet forest soils of the Pacific coastal rainforest in Canada

2017 ◽  
Vol 47 (5) ◽  
pp. 628-635 ◽  
Author(s):  
Jesper Riis Christiansen ◽  
David Levy-Booth ◽  
Cindy E. Prescott ◽  
Sue J. Grayston
Keyword(s):  
Soil Moisture ◽  
Exchange Rates ◽  
Forest Types ◽  
Soil Hydrology ◽  
Oxidation Rates ◽  
The Pacific ◽  
Upland Soils ◽  
Water Saturated ◽  
The Impact ◽  
Future Management

In a changing climate, understanding how soil hydrology impacts greenhouse gas dynamics will be important for the future management of the soils in the forests on the Canadian Pacific west coast. In a laboratory study, the impact of soil hydrology on potential net methane (CH4) exchange rates and the abundance of methanotrophs (CH4oxidation) and methanogens (CH4production) in upland and water-saturated wet soils were investigated. CH4oxidation and production rates were highest in the wet soils, which corresponded to higher numbers of methanotrophs and methanogens, indicating a link between the microbial abundance and CH4exchange rates. Also, CH4production was induced in the upland soils, indicating the presence of methanogens. The optimum soil moisture content for CH4oxidation was highest in upland soils and the wet soils sustained higher CH4oxidation rates over a broader range of soil moisture. These results underline the importance of the soil hydrological controls of CH4oxidation in contrasting soils and forest types, which deserves further attention in field-based studies.

Affects of Active Layer Detachments on Soil Gas Exchange Rates in the High Arctic

2016 ◽  
Author(s):  
Allison Neil
Keyword(s):  
Soil Moisture ◽  
Gas Exchange ◽  
Exchange Rates ◽  
Active Layer ◽  
Arctic Region ◽  
High Arctic ◽  
Gas Production ◽  
Soil Gas ◽  
Permafrost Thawing ◽  
The Impact

With changes in climate, the high Arctic region will likely experience greater changes in temperaturecompared to other regions. It is also likely that soils will be wetter due to permafrost thawing andincreased precipitation. These changes in soil moisture have already led to the occurrence of active layerdetachments. At Cape Bounty on Melville Island, these active layer detachments have disturbedsignificant proportions of whole watersheds. The impact of these disturbances on whole‐watershednutrient budgets is poorly understood. This project examines soil gas exchange (CO2, N2O, CH4) in threeactive layer detachments. At each site, soil gas exchange rates were measured across a disturbancegradient. In addition, other measurements such as soil moisture, temperature, and nutrient availabilitywere made to help understand the processes regulating trace gas production. This research will helpunderstand the connections between active layer detachments and watershed‐scale nutrient losses dueto changes in climate.

scholarly journals Soil Moisture Dynamics in Response to Precipitation and Thinning in a Semi-Dry Forest in Northern Mexico

Water ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 105
Author(s):  
Argelia E. Rascón-Ramos ◽  
Martín Martínez-Salvador ◽  
Gabriel Sosa-Pérez ◽  
Federico Villarreal-Guerrero ◽  
Alfredo Pinedo-Alvarez ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Forest Management ◽  
Water Availability ◽  
Dry Forest ◽  
Rainfall Events ◽  
Rainfall Characteristics ◽  
Northern Mexico ◽  
The Difference ◽  
The Impact ◽  
Moisture Dynamics

Understanding soil moisture behavior in semi-dry forests is essential for evaluating the impact of forest management on water availability. The objective of the study was to analyze soil moisture based in storm observations in three micro-catchments (0.19, 0.20, and 0.27 ha) with similar tree densities, and subject to different thinning intensities in a semi-dry forest in Chihuahua, Mexico. Vegetation, soil characteristics, precipitation, and volumetric water content were measured before thinning (2018), and after 0%, 40%, and 80% thinning for each micro-catchment (2019). Soil moisture was low and relatively similar among the three micro-catchments in 2018 (mean = 8.5%), and only large rainfall events (>30 mm) increased soil moisture significantly (29–52%). After thinning, soil moisture was higher and significantly different among the micro-catchments only during small rainfall events (<10 mm), while a difference was not noted during large events. The difference before–after during small rainfall events was not significant for the control (0% thinning); whereas 40% and 80% thinning increased soil moisture significantly by 40% and 53%, respectively. Knowledge of the response of soil moisture as a result of thinning and rainfall characteristics has important implications, especially for evaluating the impact of forest management on water availability.

scholarly journals Mild Abiotic Stress Affects Development and Stimulates Hormesis of Hemp Aphid Phorodon cannabis

Insects ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 420
Author(s):  
Roma Durak ◽  
Malgorzata Jedryczka ◽  
Beata Czajka ◽  
Jan Dampc ◽  
Katarzyna Wielgusz ◽  
...  
Keyword(s):  
Glutathione Transferase ◽  
Insect Pest ◽  
Mild Stress ◽  
Population Parameters ◽  
Live Feed ◽  
Average Fecundity ◽  
The Impact ◽  
Considerable Damage ◽  
Group 1 ◽  
Future Management

The hemp aphid Phorodon cannabis Passerini is a well- known (Asia, Europe) or newly emerging (North America) insect. It is a monophagous insect pest causing considerable damage in field and glasshouse cultivations. The aim of this work was to study the effects of meteorological (temperature) and agronomical (herbicide) factors on the biology of the hemp aphid. In one experiment, hemp plants were kept at constant temperatures ranging from 20 to 30 °C, and aphid survival and fecundity were measured. In a related experiment conducted at 20 °C, plants were treated with field-appropriate rates of a selective graminicide containing quizalofop-P-tefuryl (40 gL−1, 4.38%, HRAC group 1), commonly used to control weeds in hemp, and aphid enzyme activity was measured in addition to population parameters. We found that hemp aphids could live, feed and reproduce within the whole studied range of temperatures, demonstrating its great evolutionary plasticity. However, the optimal temperature for development was 25 °C, at which the insect lived and reproduced for 25 and 15 days, respectively, with an average fecundity of 7.5 nymphs per reproduction day. The herbicide treatment increased the activity of superoxide dismutase (SOD), catalase (CAT), β-glucosidase, S-glutathione transferase (GST), oxidoreductive peroxidase (POD), and polyphenol oxidase (PPO) in the aphids, but only on certain days after treatment, which indicates a mild stress in aphid tissues, related to a higher reproduction and changed feeding behavior; aphids moved from the actively growing tips compared to untreated plants. The results of these experiments are discussed in terms of the impact on the future management of this pest.

scholarly journals Towards Including Dynamic Vegetation Parameters in the EUMETSAT H SAF ASCAT Soil Moisture Products

2021 ◽  
Vol 13 (8) ◽  
pp. 1463
Author(s):  
Susan C. Steele-Dunne ◽  
Sebastian Hahn ◽  
Wolfgang Wagner ◽  
Mariette Vreugdenhil
Keyword(s):  
Soil Moisture ◽  
Interannual Variability ◽  
Incidence Angle ◽  
Pearson Correlation ◽  
The United States ◽  
Research Network ◽  
Window Width ◽  
High Frequency Variability ◽  
Vegetation Parameters ◽  
The Impact

The TU Wien Soil Moisture Retrieval (TUW SMR) approach is used to produce several operational soil moisture products from the Advanced Scatterometer (ASCAT) on the Metop series of satellites as part of the EUMETSAT Satellite Application Facility on Support to Operational Hydrology and Water Management (H SAF). The incidence angle dependence of backscatter is described by a second-order Taylor polynomial, the coefficients of which are used to normalize ASCAT observations to the reference incidence angle of 40∘ and for correcting vegetation effects. Recently, a kernel smoother was developed to estimate the coefficients dynamically, in order to account for interannual variability. In this study, we used the kernel smoother for estimating these coefficients, where we distinguished for the first time between their two uses, meaning that we used a short and fixed window width for the backscatter normalisation while we tested different window widths for optimizing the vegetation correction. In particular, we investigated the impact of using the dynamic vegetation parameters on soil moisture retrieval. We compared soil moisture retrievals based on the dynamic vegetation parameters to those estimated using the current operational approach by examining their agreement, in terms of the Pearson correlation coefficient, unbiased RMSE and bias with respect to in situ soil moisture. Data from the United States Climate Research Network were used to study the influence of climate class and land cover type on performance. The sensitivity to the kernel smoother half-width was also investigated. Results show that estimating the vegetation parameters with the kernel smoother can yield an improvement when there is interannual variability in vegetation due to a trend or a change in the amplitude or timing of the seasonal cycle. However, using the kernel smoother introduces high-frequency variability in the dynamic vegetation parameters, particularly for shorter kernel half-widths.

scholarly journals An ethic of care? Academic administration and pandemic policy

2021 ◽  
Vol 20 (1-2) ◽  
pp. 632-638
Author(s):  
Stephanie A Bryson
Keyword(s):  
Social Work ◽  
Political Theory ◽  
Pacific Northwest ◽  
Ethic Of Care ◽  
The Political ◽  
Academic Administration ◽  
The Public ◽  
Political Landscape ◽  
The Pacific ◽  
The Impact

This reflexive essay examines the adoption of an intentional ‘ethic of care’ by social work administrators in a large social work school located in the Pacific Northwest. An ethic of care foregrounds networks of human interdependence that collapse the public/private divide. Moreover, rooted in the political theory of recognition, a care ethic responds to crisis by attending to individuals’ uniqueness and ‘whole particularity.’ Foremost, it rejects indifference. Through the personal recollections of one academic administrator, the impact of rejecting indifference in spring term 2020 is described. The essay concludes by linking the rejection of indifference to the national political landscape.

scholarly journals Cable Tensile Forces Associated to Winch Design in Tethered Harvesting Operations: A Case Study from the Pacific North West

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 827
Author(s):  
Omar Mologni ◽  
Eric D. T. Nance ◽  
C. Kevin Lyons ◽  
Luca Marchi ◽  
Stefano Grigolato ◽  
...  
Keyword(s):  
Endurance Limit ◽  
Tensile Force ◽  
Force Analysis ◽  
North West ◽  
The Pacific ◽  
Work Tasks ◽  
Tensile Forces ◽  
System Activation ◽  
The Impact

Cable tensile forces in winch-assist harvesting have been investigated in order to assess the safety concerns of the technology. However, the literature is lacking, particularly in regards to the impact of winch design. In this study, a Summit Winch Assist tethering a feller-director on ground slopes up to 77% was monitored for four days. The cable tensile forces were simultaneously recorded at the harvesting and anchor machine at a frequency of 100 Hz. Cameras and GNSS devices enabled a time study of the operations and the recording of machine positions. Winch functionality and design were disclosed by the manufacturer and used for the interpretation of the results. The cable tensile forces reached 296 kN at the harvesting machine and 260 kN at the anchor machine. The slow negotiation of obstacles while moving downhill recorded the highest peaks, mainly due to threshold settings of the winch in the brake system activation. Lower but significant peaks were also recorded during stationary work tasks. The peaks, however, were limited to a few events and never exceeded the endurance limit of the cable. Overall, the study confirmed recent findings in cable tensile force analysis of active winch-assist operations and provided evidence of the underlaying mechanisms that contribute to cable tensile forces.

scholarly journals A GNSS-IR Method for Retrieving Soil Moisture Content from Integrated Multi-Satellite Data That Accounts for the Impact of Vegetation Moisture Content

2021 ◽  
Vol 13 (13) ◽  
pp. 2442
Author(s):  
Jichao Lv ◽  
Rui Zhang ◽  
Jinsheng Tu ◽  
Mingjie Liao ◽  
Jiatai Pang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Satellite Data ◽  
Vegetation Index ◽  
Soil Moisture Content ◽  
Support Vector ◽  
Observation Data ◽  
Multipath Effect ◽  
Mars Model ◽  
The Impact

There are two problems with using global navigation satellite system-interferometric reflectometry (GNSS-IR) to retrieve the soil moisture content (SMC) from single-satellite data: the difference between the reflection regions, and the difficulty in circumventing the impact of seasonal vegetation growth on reflected microwave signals. This study presents a multivariate adaptive regression spline (MARS) SMC retrieval model based on integrated multi-satellite data on the impact of the vegetation moisture content (VMC). The normalized microwave reflection index (NMRI) calculated with the multipath effect is mapped to the normalized difference vegetation index (NDVI) to estimate and eliminate the impact of VMC. A MARS model for retrieving the SMC from multi-satellite data is established based on the phase shift. To examine its reliability, the MARS model was compared with a multiple linear regression (MLR) model, a backpropagation neural network (BPNN) model, and a support vector regression (SVR) model in terms of the retrieval accuracy with time-series observation data collected at a typical station. The MARS model proposed in this study effectively retrieved the SMC, with a correlation coefficient (R2) of 0.916 and a root-mean-square error (RMSE) of 0.021 cm3/cm3. The elimination of the vegetation impact led to 3.7%, 13.9%, 11.7%, and 16.6% increases in R2 and 31.3%, 79.7%, 49.0%, and 90.5% decreases in the RMSE for the SMC retrieved by the MLR, BPNN, SVR, and MARS model, respectively. The results demonstrated the feasibility of correcting the vegetation changes based on the multipath effect and the reliability of the MARS model in retrieving the SMC.

The impact of mechanical ventilation operation strategies on indoor CO2 concentration and air exchange rates in residential buildings

2020 ◽  
pp. 1420326X2096076
Author(s):  
Pedro F. Pereira ◽  
Nuno M. M. Ramos
Keyword(s):  
Mechanical Ventilation ◽  
Air Quality ◽  
Exchange Rates ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Residential Buildings ◽  
Ventilation Strategy ◽  
The Impact ◽  
Mechanical Extraction ◽  
Air Exchange

In Portugal, residential buildings commonly have their ventilation strategy changed after commissioning. This occurs due to the building managers' willingness to reduce shared costs with the electricity needed for fan operation. However, this option is not technically supported, and the effects of such a strategy on indoor air quality-related to human pollutants are yet to be quantified. CO2 was monitored in 15 bedrooms and air exchange rates were calculated for each room. The air exchange rate values ranged from 0.18 to 0.53 h−1 when mechanical extraction ventilation was off, and from 0.45 to 0.90 h−1 when mechanical extraction ventilation was on, which represents an average increase of 119%. With the current intermittent ventilation strategy, all rooms remain above 1500 ppm for a given percentage of time, and 12 rooms presenting CO2 concentrations above 2000 ppm. Simulations of theoretical CO2 concentrations, for a non-interrupted mechanical ventilation strategy show that no rooms would accumulate CO2 concentrations above 2000 ppm, and only 25% would present CO2 concentrations above 1500 ppm. Pearson correlations between the monitored CO2 and human and spatial factors identified two relevant parameters. Those parameters correspond to ratios between CO2 generation and floor area ([Formula: see text]), and airflow with CO2 generation ([Formula: see text]). The proposed ratios could be used as ways to optimise ventilation costs and indoor air quality.

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