| 1. |
- Grau-Andrés, Roger, et al.
(författare)
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Biochar increases tree biomass in a managed boreal forest, but does not alter N2O, CH4, and CO2 emissions
- 2021
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Ingår i: GCB Bioenergy. - : Wiley. - 1757-1693 .- 1757-1707. ; 13, s. 1329-1342
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Tidskriftsartikel (refereegranskat)abstract
- Biochar soil amendment may provide the forestry sector with a formidable tool to simultaneously sequester carbon (C) in the soil and aboveground by enhancing plant productivity, yet several key uncertainties remain. Crucially, empirical evidence of long-term effects of biochar management on vegetation and on greenhouse gas emissions in forest ecosystems is scarce. Using a large field experiment in a young managed boreal forest in northern Sweden, we investigated the effects of biochar (applied either on the soil surface or mixed in the soil 8-9 years prior to this study) on supply rates of soil nutrients, on survival and growth of planted Pinus sylvestris, on community composition of the understory vegetation, and on forest floor fluxes of N2O, CH4, and CO2. We found that biochar promoted P. sylvestris survival only when biochar was applied on the soil surface. Conversely, biochar enhanced P. sylvestris growth overall, resulting in a 19% increase in C stored in biomass. Biochar also altered the composition of the understory vegetation, especially when mixed into the soil, and promoted a more resource-conservative community (i.e., with more ericaceous shrubs and less graminoids and forbs). Meanwhile, supply rates of the main soil nutrients were largely unaffected by biochar. Finally, we found that biochar did not alter overall N2O and CO2 emissions and CH4 uptake from the forest floor. Our findings show that biochar amendment increased the net C input to the system, since, besides directly increasing soil C stocks, biochar enhanced biomass growth without increasing soil C losses. Therefore, our study suggests that biochar could potentially be used for emissions abatement in intensively managed boreal forests.
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| 2. |
- Pingree, Melissa
(författare)
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Accessing the Life in Smoke: A New Application of Unmanned Aircraft Systems (UAS) to Sample Wildland Fire Bioaerosol Emissions and Their Environment
- 2019
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Ingår i: Fire. - : MDPI AG. - 2571-6255. ; 2
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Tidskriftsartikel (refereegranskat)abstract
- Wildland fire is a major producer of aerosols from combustion of vegetation and soils, but little is known about the abundance and composition of smoke’s biological content. Bioaerosols, or aerosols derived from biological sources, may be a significant component of the aerosol load vectored in wildland fire smoke. If bioaerosols are injected into the upper troposphere via high-intensity wildland fires and transported across continents, there may be consequences for the ecosystems they reach. Such transport would also alter the concept of a wildfire’s perimeter and the disturbance domain of its impact. Recent research has revealed that viable microorganisms are directly aerosolized during biomass combustion, but sampling systems and methodology for quantifying this phenomenon are poorly developed. Using a series of prescribed fires in frequently burned forest ecosystems, we report the results of employing a small rotary-wing unmanned aircraft system (UAS) to concurrently sample aerosolized bacteria and fungi, particulate matter, and micrometeorology in smoke plumes versus background conditions. Airborne impaction-based bioaerosol sampling indicated that microbial composition differed between background air and smoke, with seven unique organisms in smoke vs. three in background air. The air temperature was negatively correlated with the number of fungal colony-forming units detected. Our results demonstrate the utility of a UAS-based sampling platform for active sampling of viable aerosolized microbes in smoke arising from wildland fires. This methodology can be extended to sample viable microbes in a wide variety of emissions sampling pursuits, especially those in hazardous and inaccessible environments.
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| 3. |
- Pingree, Melissa
(författare)
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Assessing soil biological health in forest soils
- 2019
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Ingår i: Global change and forest soils : cultivating stewardship of a finite natural resource. - 9780444639981 ; :36, s. 397-426
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The sustainability of the world's forest ecosystems is greatly dependent upon the health and function of soils, unfortunately, there is ambiguity in the term "soil health" and only limited understanding of biotic function in soils. This discord leaves land managers and policy makers to formulate decisions without adequate consideration of the soil as a living resource. The following chapter is structured to provide an overview of the unique qualities and characteristics of forest soils followed by a synthesis of knowledge on functional roles of soil organisms, soil carbon (C) as the currency for microbial abundance and activity, and assessing biotic abundance and diversity in forest soils.
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| 4. |
- Pingree, Melissa, et al.
(författare)
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No evidence that conifer biochar impacts soil functioning by serving as microbial refugia in boreal soils
- 2022
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Ingår i: GCB Bioenergy. - : Wiley. - 1757-1693 .- 1757-1707. ; 14, s. 972-988
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Tidskriftsartikel (refereegranskat)abstract
- It is well established that application of biochar to soils can promote soil fertility, which ultimately may enhance plant growth. While many mechanisms have been proposed to explain this, one specific mechanism, the "microbial refugia hypothesis," suggests that biochar may provide physical protection for soil microbe from soil microfauna that otherwise exert top-down control on microbial biomass and activity. We tested the microbial refugia hypothesis by incubating two boreal soils with and without biochar derived from a wood mixture of boreal tree species (Picea abies and Pinus sylvestris), and with and without soil nematodes. We measured phospholipid fatty acids (PLFA) as a relative measure of microbial biomass, and several variables indicative of microbial activity, including extractable nutrient concentrations (NH4+, NO3-, and PO4-), heterotrophic N-2-fixation, and soil respiration. Contrary to our expectations, we found that biochar by itself did not stimulate microbial biomass or activity. Furthermore, we found that nematode addition to soil stimulated rather than depressed the biomass of several bacterial PLFA groups. Finally, interactive effects between the nematode treatment and biochar never worked in a way that supported the microbial refugia hypothesis. Our findings suggest that a typical boreal biochar applied to boreal soils may not have the same stimulatory effect on microbial biomass and activity that has been shown in some other ecosystems, and that enhanced plant growth in response to biochar addition sometimes observed in boreal environments is likely due to other mechanisms, such as direct nutrient supply from biochar or amelioration of soil pH.
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