| 1. |
- Akselsson, Cecilia, et al.
(författare)
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Weathering rates in Swedish forest soils
- 2019
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 16:22, s. 4429-4450
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Forskningsöversikt (refereegranskat)abstract
- Soil and water acidification was internationally recognised as a severe environmental problem in the late 1960s. The interest in establishing “critical loads” led to a peak in weathering research in the 1980s and 1990s, since base cation weathering is the long-term counterbalance to acidification pressure. Assessments of weathering rates and associated uncertainties have recently become an area of renewed research interest, this time due to demand for forest residues to provide renewable bioenergy. Increased demand for forest fuels increases the risk of depleting the soils of base cations produced in situ by weathering. This is the background to the research programme Quantifying Weathering Rates for Sustainable Forestry (QWARTS), which ran from 2012 to 2019. The programme involved research groups working at different scales, from laboratory experiments to modelling. The aims of this study were to (1) investigate the variation in published weathering rates of base cations from different approaches in Sweden, with consideration of the key uncertainties for each method; (2) assess the robustness of the results in relation to sustainable forestry; and (3) discuss the results in relation to new insights from the QWARTS programme and propose ways to further reduce uncertainties. In the study we found that the variation in estimated weathering rates at single-site level was large, but still most sites could be placed reliably in broader classes of weathering rates. At the regional level, the results from the different approaches were in general agreement. Comparisons with base cation losses after stem-only and whole-tree harvesting showed sites where whole-tree harvesting was clearly not sustainable and other sites where variation in weathering rates from different approaches obscured the overall balance. Clear imbalances appeared mainly after whole-tree harvesting in spruce forests in southern and central Sweden. Based on the research findings in the QWARTS programme, it was concluded that the PROFILE/ForSAFE family of models provides the most important fundamental understanding of the contribution of weathering to long-term availability of base cations to support forest growth. However, these approaches should be continually assessed against other approaches. Uncertainties in the model approaches can be further reduced, mainly by finding ways to reduce uncertainties in input data on soil texture and associated hydrological parameters but also by developing the models, e.g. to better represent biological feedbacks under the influence of climate change.
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| 2. |
- Bishop, Kevin
(författare)
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Forest water-use efficiency: Effects of climate change and management on the coupling of carbon and water processes
- 2023
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 534
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Forskningsöversikt (refereegranskat)abstract
- Forests are essential in regulating global carbon and water cycles and are critical in mitigating climate change. Water-use efficiency, defined by the ratio of plant productivity per unit water use, is widely used to quantify the interactions between forest carbon and water cycles and could be potentially used to manage the carbon and water tradeoffs of forests under different environmental conditions. This paper reviews the literature on how biophysical variables and management practices affect forest water-use efficiency. We found that water-use ef-ficiency varies greatly with forest type, species, age, environmental conditions, and forest management practices. Climatic stresses (e.g., drought and heatwave) often pose negative effects on forest instantaneous water-use ef-ficiency (WUEins), particularly over a short term. Unexpectedly, plantations and natural forests have no statistical differences in WUEins. In addition, WUEins can be effectively improved by forest thinning. These results have important implications for managing the tradeoffs between carbon sequestration and water yield of forests. Finally, four important knowledge gaps, including species-specific water-use efficiency, long-term forest water -use efficiency dynamics, water-use efficiency responses to forest management, and the integrated effects of human and natural disturbances on plantation water-use efficiency are identified and discussed.
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| 3. |
- Bishop, Kevin, et al.
(författare)
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The effects of forest management on water quality
- 2022
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 522
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Forskningsöversikt (refereegranskat)abstract
- Water quality is generally high in watercourses draining forested areas. However, forest management can lead to detrimental effects on water quality and the aquatic environment. Key concerns include diffuse pollution, carbon transport and harmful effects on freshwater ecology.Here, we undertake a review of the effects of a range of forestry activities including cultivation and site preparation, fertilisation and harvesting on water quality.We attempt to summarise the literature across a wide geographical area focusing on empirical studies. Studies report a wide range of water quality impacts after forest operations including sediment delivery, nutrient losses, carbon transport, metal and base cation releases, and changes to acidity and temperature. Spatial and temporal resolution is an important consideration. Changes in water quality at the local scale are often not seen at the catchment level and the effects of operations may be manifest many years after the work was carried out, highlighting the importance of monitoring at an appropriate spatial and temporal scale. The development of best management practices (BMPs) such as the use of buffers, low impact techniques and phased felling have led to significant changes in operational activity, reducing and, in some cases, preventing impacts on water quality. We highlight some of the most effective techniques that can protect water quality from cultivation, drainage, fertiliser and harvesting operations.We also take a forward look to technological, methodological and climatic developments that may alter forest management effects on water quality.
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| 4. |
- Ellison, David, et al.
(författare)
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On the forest cover-water yield debate : from demand- to supply-side thinking
- 2012
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 18:3, s. 806-820
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Forskningsöversikt (refereegranskat)abstract
- Several major articles from the past decade and beyond conclude the impact of reforestation or afforestation on water yield is negative: additional forest cover will reduce and removing forests will raise downstream water availability. A second group of authors argue the opposite: planting additional forests should raise downstream water availability and intensify the hydrologic cycle. Obtaining supporting evidence for this second group of authors has been more difficult due to the larger scales at which the positive effects of forests on the water cycle may be seen. We argue that forest cover is inextricably linked to precipitation. Forest-driven evapotranspiration removed from a particular catchment contributes to the availability of atmospheric moisture vapor and its cross-continental transport, raising the likelihood of precipitation events and increasing water yield, in particular in continental interiors more distant from oceans. Seasonal relationships heighten the importance of this phenomenon. We review the arguments from different scales and perspectives. This clarifies the generally beneficial relationship between forest cover and the intensity of the hydrologic cycle. While evidence supports both sides of the argument trees can reduce runoff at the small catchment scale at larger scales, trees are more clearly linked to increased precipitation and water availability. Progressive deforestation, land conversion from forest to agriculture and urbanization have potentially negative consequences for global precipitation, prompting us to think of forest ecosystems as global public goods. Policy-making attempts to measure product water footprints, estimate the value of ecosystem services, promote afforestation, develop drought mitigation strategies and otherwise manage land use must consider the linkage of forests to the supply of precipitation.
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| 5. |
- Finlay, Roger, et al.
(författare)
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Reviews and syntheses : Biological weathering and its consequences at different spatial levels - from nanoscale to global scale
- 2020
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 17:6, s. 1507-1533
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Forskningsöversikt (refereegranskat)abstract
- Plant nutrients can be recycled through microbial decomposition of organic matter but replacement of base cations and phosphorus, lost through harvesting of biomass/biofuels or leaching, requires de novo supply of fresh nutrients released through weathering of soil parent material (minerals and rocks). Weathering involves physical and chemical processes that are modified by biological activity of plants, microorganisms and animals. This article reviews recent progress made in understanding biological processes contributing to weathering. A perspective of increasing spatial scale is adopted, examining the consequences of biological activity for weathering from nanoscale interactions, through in vitro and in planta microcosm and meso-cosm studies, to field experiments, and finally ecosystem and global level effects. The topics discussed include the physical alteration of minerals and mineral surfaces; the composition, amounts, chemical properties, and effects of plant and microbial secretions; and the role of carbon flow (including stabilisation and sequestration of C in organic and inorganic forms). Although the predominant focus is on the effects of fungi in forest ecosystems, the properties of biofilms, including bacterial interactions, are also discussed. The implications of these biological processes for modelling are discussed, and we attempt to identify some key questions and knowledge gaps, as well as experimental approaches and areas of research in which future studies are likely to yield useful results. A particular focus of this article is to improve the representation of the ways in which biological processes complement physical and chemical processes that mobilise mineral elements, making them available for plant uptake. This is necessary to produce better estimates of weathering that are required for sustainable management of forests in a post-fossil-fuel economy. While there are abundant examples of nanometre- and micrometre-scale physical interactions between microorganisms and different minerals, opinion appears to be divided with respect to the quantitative significance of these observations for overall weathering. Numerous in vitro experiments and microcosm studies involving plants and their associated microorganisms suggest that the allocation of plant-derived carbon, mineral dissolution and plant nutrient status are tightly coupled, but there is still disagreement about the extent to which these processes contribute to field-scale observations. Apart from providing dynamically responsive pathways for the allocation of plant-derived carbon to power dissolution of minerals, mycorrhizal mycelia provide conduits for the long-distance trans-portation of weathering products back to plants that are also quantitatively significant sinks for released nutrients. These mycelial pathways bridge heterogeneous substrates, reducing the influence of local variation in C : N ratios. The production of polysaccharide matrices by biofilms of interacting bacteria and/or fungi at interfaces with mineral surfaces and roots influences patterns of production of antibiotics and quorum sensing molecules, with concomitant effects on microbial community structure, and the qualitative and quantitative composition of mineral-solubilising compounds and weathering products. Patterns of carbon allocation and nutrient mobilisation from both organic and inorganic substrates have been studied at larger spatial and temporal scales, including both ecosystem and global levels, and there is a generally wider degree of acceptance of the systemic effects of microorganisms on patterns of nutrient mobilisation. Theories about the evolutionary development of weathering processes have been advanced but there is still a lack of information connecting processes at different spatial scales. Detailed studies of the liquid chemistry of local weathering sites at the micrometre scale, together with upscaling to soil-scale dissolution rates, are advocated, as well as new approaches involving stable isotopes.
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| 6. |
- Lucas, Richard, et al.
(författare)
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A meta-analysis of the effects of nitrogen additions on base cations : Implications for plants, soils, and streams
- 2011
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Ingår i: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 262:2, s. 95-104
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Forskningsöversikt (refereegranskat)abstract
- The dominant base cations (BC: i.e., Ca(2+), Mg(2+), K(+), and Na(+)) are important in buffering soil and water acidity in both terrestrial and aquatic ecosystems. Ca(2+)., Mg(2+), and K(+) are also important in many plant physiological functions. Because BC availability is affected by changes in the nitrogen (N) cycle, we conducted a meta-analysis of previously published data to determine if N fertilization alters the availability of BC in terrestrial and stream ecosystems across biomes. We include data from 107 independent studies published in 62 different articles, taking a holistic perspective on BC by examining their responses to added N in plant foliage, bulk soil, soil solution, and stream water. Our results suggest N fertilization may accelerate BC loss from terrestrial ecosystems over time periods less than five years. We found that N additions resulted in an overall 24% decrease in the availability of exchangeable Ca(2+), Mg(2+), and K(+) in the bulk soil of boreal forest, temperate forest, and grassland biomes. Collectively, responses of BC in boreal forest, temperate forest, tropical forest, and grassland biomes increased following N fertilization by about 71% in soil solution and 48% in stream waters. Additionally, BC responses in foliage decreased in boreal forest and temperate forest biomes following N additions over time periods less than five years, but there were no significant changes over longer time periods. Despite large short-term shifts in BC responses following N additions, we did not find evidence of widespread negative impacts on ecosystems over time periods greater than five years. This analysis suggests effects of N addition on the availability of exchangeable BC may diminish over time. Although the effects on BC can be substantial over periods less than five years, there is little available evidence that N fertilization has had large-scale detrimental effects on the availability of BC needed for plant growth within terrestrial or aquatic ecosystems.
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| 7. |
- Noumonvi, Koffi Dodji, et al.
(författare)
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The Kulbäcksliden research infrastructure : a unique setting for northern peatland studies
- 2023
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Ingår i: Frontiers in Earth Science. - : Frontiers Media S.A.. - 2296-6463. ; 11
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Forskningsöversikt (refereegranskat)abstract
- Boreal peatlands represent a biogeochemically unique and diverse environment in high-latitude landscape. They represent a long-term globally significant sink for carbon dioxide and a source of methane, hence playing an important role in regulating the global climate. There is an increasing interest in deciphering peatland biogeochemical processes to improve our understanding of how anthropogenic and climate change effects regulate the peatland biogeochemistry and greenhouse gas balances. At present, most studies investigating land-atmosphere exchanges of peatland ecosystems are commonly based on single-tower setups, which require the assumption of homogeneous conditions during upscaling to the landscape. However, the spatial organization of peatland complexes might feature large heterogeneity due to its varying underlying topography and vegetation composition. Little is known about how well single site studies represent the spatial variations of biogeochemical processes across entire peatland complexes. The recently established Kulbäcksliden Research Infrastructure (KRI) includes five peatland study sites located less than 3 km apart, thus providing a unique opportunity to explore the spatial variation in ecosystem-scale processes across a typical boreal peatland complex. All KRI sites are equipped with eddy covariance flux towers combined with installations for detailed monitoring of biotic and abiotic variables, as well as catchment-scale hydrology and hydrochemistry. Here, we review studies that were conducted in the Kulbäcksliden area and provide a description of the site characteristics as well as the instrumentation available at the KRI. We highlight the value of long-term infrastructures with ecosystem-scale and replicated experimental sites to advance our understanding of peatland biogeochemistry, hydrology, ecology, and its feedbacks on the environment and climate system.
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| 8. |
- Wu, Pianpian, et al.
(författare)
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The importance of bioconcentration into the pelagic food web base for methylmercury biomagnification : A meta-analysis
- 2019
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 646, s. 357-367
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Forskningsöversikt (refereegranskat)abstract
- Methylmercury (MeHg) transfer from water into the base of the food web (bioconcentration) and subsequent biomagnification in the aquatic food web leads to most of the MeHg in fish. But how important is bioconcentration compared to biomagnification in predicting MeHg in fish? To answer this question we reviewed articles in which MeHg concentrations in water, plankton (seston and/or zooplankton), as well as fish (planktivorous and small omnivorous fish) were reported. This yielded 32 journal articles with data from 59 aquatic ecosystems at 22 sites around the world. Although there are many case studies of particular aquatic habitats and specific geographic areas that have examined MeHg bioconcentration and biomagnification, we performed a meta-analysis of such studies. Aqueous MeHg was not a significant predictor of MeHg in fish, but MeHg in seston i.e., the base of the aquatic food web, predicted 63% of the variability in fish MeHg. The MeHg bioconcentration factors (i.e., transfer of MeHg from water to seston; BCFw-s) varied from 3 to 7 orders of magnitude across sites and correlated significantly with MeHg in fish. The MeHg biomagnification factors from zooplankton to fish varied much less (logBMFz-f, 0.75 ± 0.31), and did not significantly correlate with fish MeHg, suggesting that zooplanktivory is not as important as bioconcentration in the biomagnification of fish MeHg across the range of ecosystems represented in our meta-analysis. Partial least square (PLS) and linear regression analyses identified several environmental factors associated with increased BCF, including low dissolved organic carbon, low pH, and oligotrophy. Our study reveals the widespread importance of MeHg bioconcentration into the base of the aquatic food web for MeHg at higher trophic levels in aquatic food webs, as well as the major influences on the variability in this bioconcentration.
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