| 1. |
- Bergholm, Johan, et al.
(författare)
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Nitrogen fluxes after clear-cutting. Ground vegetation uptake and stump/root immobilisation reduce N leaching after experimental liming, acidification and N fertilisation
- 2015
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 342, s. 64-75
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Tidskriftsartikel (refereegranskat)abstract
- Clear-cutting often results in a dramatic change in the soil nitrogen (N) balance. This study analysed the fate of inorganic soil N over four years (1992-1995) in a new clear-cut containing three replicate blocks. Treatments comprised control (0), 6000 kg CaCO3 ha(-1) (Ca), 600 kg sulphur powder ha(-1) (S) and 600 kg urea-N ha(-1) (U), applied during 1976-1987 to a Norway spruce (Picea abies) forest. Trees were cut in March 1992, after which stems, tops and branches were removed from the 12 experimental plots. Spruce seedlings were planted in May 1992. Clear-cutting resulted in accumulation of approx. 50 kg inorganic N ha(-1) in the 30 cm deep topsoil of the 0, S and U treatments and 25 kg N ha(-1) in the Ca treatment by October of 1992. During the next two years, the inorganic pools increased (S), stabilised (0 and U) or declined (Ca), but from the end of the third year all inorganic pools decreased. Plant cover gradually increased with dominance of Deschampsia flexuosa. Mean plant N uptake in grasses, forbs and spruce seedlings was estimated at 95 (0), 139 (Ca), 52 (S) and 121 (U) kg N ha(-1) for the four-year period. Nitrogen leaching at 50 cm depth was dominated by NO3-N and culminated during the second (Ca and U) and third (0 and S) years. Cumulative N leaching for the four-year period was lower for U and Ca (28 and 31 kg N ha(-1)) than for 0 and S (53 and 81 kg N ha(-1)), and was inversely correlated with plant N uptake. Nitrogen immobilisation in stumps and root necromass (including spruce and grass roots) was calculated to be 35-45 kg N ha(-1) during this period. The four-year N balance showed 5-17% higher inputs (net mineralisation and deposition) than outputs (plant uptake, leaching, immobilisation in dead stumps/roots and accumulation of inorganic N). Gaseous N losses were not studied, but high pH and high NO3--N formation in the organic layers of the Ca treatment in 1992 might have favoured denitrification, which can partly explain the lower amount of inorganic N remaining in this treatment. A novel finding was that stump and dead root immobilisation of N was quantitatively important. A second novel finding was that lime application, although stimulating nitrification, also stimulated plant N uptake so much that nitrate leaching was reduced in comparison with the control and sulphur treatments. (C) 2015 Elsevier B.V. All rights reserved.
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| 2. |
- Hyvönen, Riitta, et al.
(författare)
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Carbon and nitrogen pools and mineralization rates in boreal forest soil after stump harvesting
- 2016
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 377, s. 61-70
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Tidskriftsartikel (refereegranskat)abstract
- The use of forest-derived biomass has steadily increased in Finland and Sweden during the past decades leading to more intensive forest management practices in the region, such as whole-tree harvesting, both above- and belowground. Stump harvesting results in a direct removal of stump and coarse-root carbon (C) from the stand and can cause extensive soil disturbance, which has been suggested to increase C mineralization. In this study, the effects of stump harvesting on soil C and nitrogen (N) mineralization, and soil surface disturbance were studied in two different clear-felled Norway spruce (Picea abies) sites in Central Finland. The treatments were whole-tree harvesting (WTH, removal of stems and logging residues), and WTH and stump harvesting (WTH + S). Both sites, Honkola (2 stands) and Haukilahti (6 stands) were mounded. In both treatments, soil samples were taken from different soil layers down to a total depth of 20 cm in the mineral soil from (i) mounds, (ii) undisturbed soil and (iii) pits. The sampling was performed 11-12 years after treatments. Soil C and N mineralization rates were determined in laboratory incubation experiments. In addition, total C and N pools (g m(2)) were estimated for each disturbance class and soil layer. Soil C and N pools had a tendency to be lower following stump harvesting, but no statistically significant treatment effect was detected. Stump harvesting increased soil mixing as indicated by a significant decrease in C concentration in the mound disturbance class. There was no significant effect of stump harvesting on soil C mineralization rates. A combination of mineralization rates and soil pool data showed that field C mineralization (g CO2-C m(-2) yr(-1)) did not significantly differ between stands where stumps were removed or were retained. Further, stump harvesting did not seem to have any stimulating effect on soil CO2 efflux 11-12 years after treatment. (C) 2016 Elsevier B.V. All rights reserved.
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| 3. |
- Persson, Tryggve, et al.
(författare)
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Long-term effects of stump harvesting and site preparation on pools and fluxes of soil carbon and nitrogen in central Sweden
- 2017
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 32, s. 222-229
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Tidskriftsartikel (refereegranskat)abstract
- Clear-cutting and subsequent site preparation is a common forest management practice in the Nordic countries. Slash and stumps have been suggested to replace fossil fuels in district heating plants. Stump/root removal from clear-cuts will reduce the amount of decomposable substrate in the soil and thus decrease soil CO2 emission, but stump lifting is also supposed to stimulate CO2 efflux and counteract CO2 reduction. To determine the effects of stump/root harvesting in relation to site preparation (stumps retained) on pools and fluxes of carbon (C) and nitrogen (N) after a period of 20-30 years, soil sampling was performed in four pairs of stump/root harvesting (S) and patch scarification (P) stands in central Sweden in 2009. Stump/root harvesting resulted in a significantly lower soil C pool in the humus layer. Annual heterotrophic respiration (R-H) in the whole soil profile was significantly lower after the S than after the P treatment, the mean difference being 38 +/- 23g CO2-Cm(-2)year(-1) (95% CI). This difference was larger than corresponding data from stump/root decomposition models (11-18g CO2-Cm(-2)year(-1)), but both empirical and model data showed that stump/root harvesting will reduce heterotrophic soil CO2 emissions to the atmosphere during the actual period.
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| 4. |
- Persson, Tryggve, et al.
(författare)
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Long-Term Impact of Liming on Soil C and N in a Fertile Spruce Forest Ecosystem
- 2021
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Ingår i: Ecosystems. - : Springer Science and Business Media LLC. - 1432-9840 .- 1435-0629. ; 24, s. 968-987
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Tidskriftsartikel (refereegranskat)abstract
- Liming can counteract acidification in forest soils, but the effects on soil C and N pools and fluxes over long periods are less well understood. Replicated plots in an acidic and N-rich 40-year-old Norway spruce (Picea abies) forest in SW Sweden (Hasslov) were treated with 0, 3.45 and 8.75 Mg ha(-1)of dolomitic lime (D0, D2 and D3) in 1984. Between 1984 and 2016, soil organic C to 30 cm depth increased by 28 Mg ha(-1)(30% increase) in D0 and decreased by 9 Mg ha(-1)(9.4% decrease) in D3. The change in D2 was not significant (+ 2 Mg ha(-1)). Soil N pools changed proportionally to those in soil C pools. The C and N changes occurred almost exclusively in the top organic layer. Non-burrowing earthworms responded positively to liming and stimulated heterotrophic respiration in this layer in both D2 and D3. Burrowing earthworms in D3 further accelerated C and N turnover and loss of soil. The high soil C and N loss at our relatively N-rich site differs from studies of N-poor sites showing no C and N loss. Earthworms need both high pH and N-rich food to reach high abundance and biomass. This can explain why liming of N-rich soils often results in decreasing C and N pools, whereas liming of N-poor soils with few earthworms will not show any change in soil C and N. Extractable nitrate N was always higher in D3 than in D2 and D0. After 6 years (1990), potential nitrification was much higher in D3 (197 kg N ha(-1)) than in D0 (36 kg N ha(-1)), but this difference decreased during the following years, when also the unlimed organic layers showed high nitrification potential. Our experiment finds that high-dose liming of acidic N-rich forest soils produces an initial pulse of soil heterotrophic respiration and increases in earthworm biomass, which together cause long-term declines in soil C and N pools.
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| 5. |
- Persson, Tryggve, et al.
(författare)
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Which macroarthropods prefer tree stumps over soil and litter substrates?
- 2013
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 290, s. 30-39
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Tidskriftsartikel (refereegranskat)abstract
- Tree stumps are a potential bioenergy resource to replace fossil fuels and meet the targets for reduced CO2 emissions. However, the effects of stump harvesting on wood-dependent organisms are poorly known. This study assessed the abundances of macroarthropods, especially non-coleopteran groups, in wood, bark and 'periphery' of stumps in comparison with soil to evaluate which species/taxa prefer stumps over soil and would risk a significant population decline following extensive stump harvesting. To assess the effects of stump age on species and individual numbers, 5-, 10- and 20-yr-old stumps were studied at three sites in southern and central Sweden. For each site and age class, stumps of Scots pine (Pious sylvestris) and Norway spruce (Picea abies) were compared. Samples of wood and bark were taken from the full height of the stump and samples of periphery and soil to a depth of 10 cm. The samples were placed in Tullgren funnels for animal extraction during 4 days. A total of 56 species or other taxonomic groups not belonging to Coleoptera were identified. Bark (including the space between bark and wood) had significantly lower species richness of non-coleopteran macroarthropods but higher abundance per m(2) (of cut stump surface) than soil in 10-yr-old stands, which on average contained higher abundances than the other age classes. No significant differences were found between spruce and pine stumps, indicating that one of the tree species can act as a substitute after stump harvesting of the other. Viewed over all substrates, Diplopoda, Coleoptera, Diptera (larvae) and Homoptera contributed most to the total abundance (29, 20, 17 and 15%, respectively). Of these groups, Diplopoda were much more abundant in bark (98%) than in soil (2%). The most common diplopod species was Proteroiulus fuscus, which often demonstrated 100-fold higher abundances (per sample unit) in bark and wood than in soil. Six species/taxa had clearly higher abundances in stumps than in soil. Stump harvesting would thus markedly reduce preferred habitats for these taxa. It is also possible that some species generally considered as soil animals might be occasionally dependent on stumps for, e.g. egg-laying and hatching. For such species, stump harvesting would be more detrimental than indicated by this population survey. (C) 2012 Elsevier B.V. All rights reserved.
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| 6. |
- Taylor, Astrid, et al.
(författare)
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Ant and Earthworm Bioturbation in Cold-Temperate Ecosystems
- 2019
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Ingår i: Ecosystems. - : Springer Science and Business Media LLC. - 1432-9840 .- 1435-0629. ; 22, s. 981-994
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Tidskriftsartikel (refereegranskat)abstract
- In temperate ecosystems, earthworms and ants are the most important organisms for bioturbation. Little is known about how these groups contribute to bioturbation in different environments and to what extent overall bioturbation depends on their diversity. We developed a formula that allows quantification of annual earthworm bioturbation, thereby taking differences between earthworm ecotypes into account. With this formula, we calculated earthworm bioturbation at three sites, each with vegetation types typically found in Northern Europe. Earthworm bioturbation was low (1 Mg dry soil ha(-1) y(-1)) in Scots pine and Norway spruce forests with acidic soil (pH 3.9-4.4) and high (between 15 and 34 Mg dry soil ha(-1) y(-1)) in broadleaf forests, grasslands, alder carr and spruce forests on calcareous soil. Burrowing (endogeic and anecic) earthworms accounted for most of the earthworm bioturbation, and these worms had the highest population densities at moderate-to-high soil pH (pH 5-7.2). Estimates of ant bioturbation at the same sites were based on nest abundance, size and residence time. Mean ant bioturbation varied between 0.2 and 1 Mg dry soil ha(-1) y(-1), but individual plots had up to 2.4 Mg dry soil ha(-1) y(-1). In soils with pH higher than 5, the relative contribution of ants to total bioturbation was only 1-5%. Ant bioturbation was higher than earthworm bioturbation only in some forest soils with pH 3.9-4.4. Thus, earthworms appear to be the dominant cause of bioturbation in most types of terrestrial ecosystems in the cold-temperate areas of Europe and when information on local earthworm communities and monthly soil temperatures is available, bioturbation can be quantified using the presented 'earthworm bioturbation formula'.
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| 7. |
- Al-Mashhadi, Ammar, et al.
(författare)
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Changes of arterial pressure following relief of obstruction in adults with hydronephrosis
- 2018
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Ingår i: Upsala Journal of Medical Sciences. - : Uppsala Medical Society. - 0300-9734 .- 2000-1967. ; 123:4, s. 216-224
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Tidskriftsartikel (refereegranskat)abstract
- Background: As much as 20% of all cases of hypertension are associated with kidney malfunctions. We have previously demonstrated in animals and in pediatric patients that hydronephrosis causes hypertension, which was attenuated by surgical relief of the ureteropelvic junction (UPJ) obstruction. This retrospective cohort study aimed to investigate: (1) the proposed link between hydronephrosis, due to UPJ obstruction, and elevated arterial pressure in adults; and (2) if elevated blood pressure in patients with hydronephrosis might be another indication for surgery.Materials and methods: Medical records of 212 patients undergoing surgical management of hydronephrosis, due to UPJ obstruction, between 2000 and 2016 were assessed. After excluding patients with confounding conditions and treatments, paired arterial pressures (i.e. before/after surgery) were compared in 49 patients (35 years old; 95% CI 29–39). Split renal function was evaluated by using mercaptoacetyltriglycine (MAG3) renography before surgical management of the hydronephrotic kidney.Results: Systolic (−11 mmHg; 95% CI 6–15 mmHg), diastolic (−8 mmHg; 95% CI 4–11 mmHg), and mean arterial (-9 mmHg; 95% CI 6–12) pressures were significantly reduced after relief of the obstruction (p < 0.001). Split renal function of the hydronephrotic kidney was 39% (95% CI 37–41). No correlations were found between MAG3 and blood pressure level before surgery or between MAG3 and the reduction of blood pressure after surgical management of the UPJ obstruction.Conclusions: In adults with hydronephrosis, blood pressure was reduced following relief of the obstruction. Our findings suggest that elevated arterial pressure should be taken into account as an indication to surgically correct hydronephrosis.
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| 8. |
- Al-Mashhadi, Ammar Nadhom Farman, et al.
(författare)
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Changes in arterial pressure and markers of nitric oxide homeostasis and oxidative stress following surgical correction of hydronephrosis in children
- 2018
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Ingår i: Pediatric nephrology (Berlin, West). - : Springer. - 0931-041X .- 1432-198X. ; 33:4, s. 639-649
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Tidskriftsartikel (refereegranskat)abstract
- Objective Recent clinical studies have suggested an increased risk of elevated arterial pressure in patients with hydronephrosis. Animals with experimentally induced hydronephrosis develop hypertension, which is correlated to the degree of obstruction and increased oxidative stress. In this prospective study we investigated changes in arterial pressure, oxidative stress, and nitric oxide (NO) homeostasis following correction of hydronephrosis.Methods Ambulatory arterial pressure (24 h) was monitored in pediatric patients with hydronephrosis (n = 15) before and after surgical correction, and the measurements were compared with arterial pressure measurements in two control groups, i.e. healthy controls (n = 8) and operated controls (n = 8). Markers of oxidative stress and NO homeostasis were analyzed in matched urine and plasma samples.Results The preoperative mean arterial pressure was significantly higher in hydronephrotic patients [83 mmHg; 95% confidence interval (CI) 80–88 mmHg] than in healthy controls (74 mmHg; 95% CI 68–80 mmHg; p < 0.05), and surgical correction of ureteral obstruction reduced arterial pressure (76 mmHg; 95% CI 74–79 mmHg; p < 0.05). Markers of oxidative stress (i.e., 11- dehydroTXB2, PGF2α, 8-iso-PGF2α, 8,12-iso-iPF2α-VI) were significantly increased (p < 0.05) in patients with hydronephrosis compared with both control groups, and these were reduced following surgery (p < 0.05). Interestingly, there was a trend for increased NO synthase activity and signaling in hydronephrosis, which may indicate compensatory mechanism(s).Conclusion This study demonstrates increased arterial pressure and oxidative stress in children with hydronephrosis compared with healthy controls, which can be restored to normal levels by surgical correction of the obstruction. Once reference data on ambulatory blood pressure in this young age group become available, we hope cut-off values can be defined for deciding whether or not to correct hydronephrosis surgically.Keywords Blood pressure . Hydronephrosis . Hypertension . Nitric oxide . Oxidative stress . Ureteral obstruction
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| 9. |
- Al-Mashhadi, Ammar Nadhom Farman, et al.
(författare)
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Surgical treatment reduces blood pressure in children with unilateral congenital hydronephrosis
- 2015
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Ingår i: Journal of Pediatric Urology. - : Elsevier BV. - 1477-5131 .- 1873-4898. ; 11:2, s. 91.e1-91.e6
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Tidskriftsartikel (refereegranskat)abstract
- Objective Renal disorders can cause hypertension, but less is known about the influence of hydronephrosis on blood pressure. Hydronephrosis due to pelvo-ureteric junction obstruction (PUJO) is a fairly common condition (incidence in newborns of 0.5-1%). Although hypertensive effects of hydronephrosis have been suggested, this has not been substantiated by prospective studies in humans [1-3]. Experimental studies with PUJO have shown that animals with induced hydronephrosis develop salt-sensitive hypertension, which strongly correlate to the degree of obstruction [4-7]. Moreover, relief of the obstruction normalized blood pressure [8]. In this first prospective study our aim was to study the blood pressure pattern in pediatric patients with hydronephrosis before and after surgical correction of the ureteral obstruction. Specifically, we investigated if preoperative blood pressure is reduced after surgery and if split renal function and renographic excretion curves provide any prognostic information. Patients and methods Twelve patients with unilateral congenital hydronephrosis were included in this prospective study. Ambulatory blood pressure (24 h) was measured preoperatively and six months after surgery. Preoperative evaluations of bilateral renal function by Tc99m-MAG3 scintigraphy, and renography curves, classified according to O'Reilly, were also performed. Results As shown in the summary figure, postoperative systolic (103 +/- 2 mmHg) and diastolic (62 +/- 2 mmHg) blood pressure were significantly lower than those obtained preoperatively (110 +/- 4 and 69 +/- 2 mmHg, respectively), whereas no changes in circadian variation or pulse pressure were observed. Renal functional share of the hydronephrotic kidney ranged from 11 to 55%. There was no correlation between the degree of renal function impairment and the preoperative excretory pattern, or between the preoperative excretory pattern and the blood pressure reduction postoperatively. However, preoperative MAG3 function of the affected kidney correlated with the magnitude of blood pressure change after surgery. Discussion Correction of the obstruction lowered blood pressure, and the reduction in blood pressure appeared to correlate with the degree of renal functional impairment, but not with the excretory pattern. Thus, in the setting of hypertension, it appears that the functional share of the hydronephrotic kidney should be considered an indicator of the need for surgery, whereas the renography curve is less reliable. The strength of the present study is the prospective nature and that ambulatory blood pressure monitoring was used. Future longitudinal prolonged follow-up studies are warranted to confirm the present findings, and to understand if a real nephrogenic hypertension with potential necessity of treatment will develop. Conclusion This novel prospective study in patients with congenital hydronephrosis demonstrates a reduction in blood pressure following relief of the obstruction. Based on the present results, we propose that the blood pressure level should also be taken into account when deciding whether to correct hydronephrosis surgically or not.
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| 10. |
- Appelstrand, Marie, et al.
(författare)
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Kan ett ökat biobränsleuttag kombineras med god miljöhänsyn? : Resultat av en intervjustudie med skogsbrukets aktörer
- 2017
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Ingår i: Stubbskörd - hur påverkas klimat och miljö? - hur påverkas klimat och miljö?. - 9789157694546 - 9789157694553 ; , s. 76-79
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Det är många maskiner och människor engagerade i en avverkning där man tar ut virke, grot och stubbar. En serie djupintervjuer med olika intressenter och aktörer visar att det finns stora brister i planering, logistik och kommunikation mellan de olika leden i kedjan, speciellt då flera olika entreprenörer är inblandade. Svaren visar också att det finns ett behov av bättre utbildning – och att man måste bli bättre på att ta tillvara den kunskap som finns, framförallt hos maskinförare och entreprenörer.
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