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361.
Lars ?stlund Greger H?rnberg Thomas H. DeLuca Lars Liedgren Peder Wikstr?m Olle Zackrisson Torbj?rn Josefsson 《Ambio》2015,44(6):508-520
Anthropogenic deforestation has shaped ecosystems worldwide. In subarctic ecosystems, primarily inhabited by native peoples, deforestation is generally considered to be mainly associated with the industrial period. Here we examined mechanisms underlying deforestation a thousand years ago in a high-mountain valley with settlement artifacts located in subarctic Scandinavia. Using the Heureka Forestry Decision Support System, we modeled pre-settlement conditions and effects of tree cutting on forest cover. To examine lack of regeneration and present nutrient status, we analyzed soil nitrogen. We found that tree cutting could have deforested the valley within some hundred years. Overexploitation left the soil depleted beyond the capacity of re-establishment of trees. We suggest that pre-historical deforestation has occurred also in subarctic ecosystems and that ecosystem boundaries were especially vulnerable to this process. This study improves our understanding of mechanisms behind human-induced ecosystem transformations and tree-line changes, and of the concept of wilderness in the Scandinavian mountain range.
Electronic supplementary material
The online version of this article (doi:10.1007/s13280-015-0634-z) contains supplementary material, which is available to authorized users. 相似文献362.
Replacing monocultures with mixed-species stands: Ecosystem service implications of two production forest alternatives in Sweden 总被引:2,自引:0,他引:2
Adam Felton Urban Nilsson Johan Sonesson Annika M. Felton Jean-Michel Roberge Thomas Ranius Martin Ahlström Johan Bergh Christer Björkman Johanna Boberg Lars Drössler Nils Fahlvik Peichen Gong Emma Holmström E. Carina H. Keskitalo Maartje J. Klapwijk Hjalmar Laudon Tomas Lundmark Mats Niklasson Annika Nordin Maria Pettersson Jan Stenlid Anna Sténs Kristina Wallertz 《Ambio》2016,45(2):124-139
Whereas there is evidence that mixed-species approaches to production forestry in general can provide positive outcomes relative to monocultures, it is less clear to what extent multiple benefits can be derived from specific mixed-species alternatives. To provide such insights requires evaluations of an encompassing suite of ecosystem services, biodiversity, and forest management considerations provided by specific mixtures and monocultures within a region. Here, we conduct such an assessment in Sweden by contrasting even-aged Norway spruce (Picea abies)-dominated stands, with mixed-species stands of spruce and birch (Betula pendula or B. pubescens), or spruce and Scots pine (Pinus sylvestris). By synthesizing the available evidence, we identify positive outcomes from mixtures including increased biodiversity, water quality, esthetic and recreational values, as well as reduced stand vulnerability to pest and pathogen damage. However, some uncertainties and risks were projected to increase, highlighting the importance of conducting comprehensive interdisciplinary evaluations when assessing the pros and cons of mixtures. 相似文献
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Joachim Sturve Lennart Balk Birgitta Liewenborg Margaretha Adolfsson-Erici Lars Förlin Bethanie Carney Almroth 《Environmental science and pollution research international》2014,21(24):13758-13768
Oil spills occur commonly, and chemical compounds originating from oil spills are widespread in the aquatic environment. In order to monitor effects of a bunker oil spill on the aquatic environment, biomarker responses were measured in eelpout (Zoarces viviparus) sampled along a gradient in Göteborg harbor where the oil spill occurred and at a reference site, 2 weeks after the oil spill. Eelpout were also exposed to the bunker oil in a laboratory study to validate field data. The results show that eelpout from the Göteborg harbor are influenced by contaminants, especially polycyclic aromatic hydrocarbons (PAHs), also during “normal” conditions. The bunker oil spill strongly enhanced the biomarker responses. Results show elevated ethoxyresorufin-O-deethylase (EROD) activities in all exposed sites, but, closest to the oil spill, the EROD activity was partly inhibited, possibly by PAHs. Elevated DNA adduct levels were also observed after the bunker oil spill. Chemical analyses of bile revealed high concentrations of PAH metabolites in the eelpout exposed to the oil, and the same PAH metabolite profile was evident both in eelpout sampled in the harbor and in the eelpout exposed to the bunker oil in the laboratory study. 相似文献
367.
Potassium, phosphorus, or nitrogen limit root allocation, tree growth, or litter production in a lowland tropical forest 总被引:5,自引:0,他引:5
Wright SJ Yavitt JB Wurzburger N Turner BL Tanner EV Sayer EJ Santiago LS Kaspari M Hedin LO Harms KE Garcia MN Corre MD 《Ecology》2011,92(8):1616-1625
We maintained a factorial nitrogen (N), phosphorus (P), and potassium (K) addition experiment for 11 years in a humid lowland forest growing on a relatively fertile soil in Panama to evaluate potential nutrient limitation of tree growth rates, fine-litter production, and fine-root biomass. We replicated the eight factorial treatments four times using 32 plots of 40 x 40 m each. The addition of K was associated with significant decreases in stand-level fine-root biomass and, in a companion study of seedlings, decreases in allocation to roots and increases in height growth rates. The addition of K and N together was associated with significant increases in growth rates of saplings and poles (1-10 cm in diameter at breast height) and a further marginally significant decrease in stand-level fine-root biomass. The addition of P was associated with a marginally significant (P = 0.058) increase in fine-litter production that was consistent across all litter fractions. Our experiment provides evidence that N, P, and K all limit forest plants growing on a relatively fertile soil in the lowland tropics, with the strongest evidence for limitation by K among seedlings, saplings, and poles. 相似文献
368.
Pablo Garrido Lars Edenius Grzegorz Mikusiski Anna Skarin Anna Jansson Carl-Gustaf Thulin 《Ambio》2021,50(1):101
Large herbivores play key roles in terrestrial ecosystems. Continuous defaunation processes have produced cascade effects on plant community composition, vegetation structure, and even climate. Wood-pastures were created by traditional management practices that have maintained open structures and biodiversity for millennia. In Europe, despite the broad recognition of their biological importance, such landscapes are declining due to land-use changes. This calls for finding urgent solutions for wood-pasture conservation. To test whether introducing an ecological replacement of an extinct wild horse could have positive effects on wood-pasture restoration, we designed a 3-year rewilding experiment. Horses created a more open wood-pasture structure by browsing on seedlings and saplings, affected tree composition via selective browsing and controlled the colonization of woody vegetation in grassland-dominated areas. Thus, rewilding could be a potential avenue for wood-pasture restoration and biodiversity conservation. However, such benefits may not materialize without a necessary paradigm and political shift.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01320-0) contains supplementary material, which is available to authorized users. 相似文献
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Nina Nevala-Puranen Lars Sörensen 《International journal of occupational safety and ergonomics》2013,19(1-2):77-88
In agriculture, occupational injuries are common, and several of them lead to permanent physical disability. The objective of this case study was to assess the strain and the ergonomic needs of four farmers (aged 34–49 years) with physical disabilities. A maximal bicycle ergometer test or an arm-crank test was done to assess their maximal heart rate (HR max) and maximal oxygen consumption (V02max). The strain at work was analyzed by measuring heart rate (HR), muscle activity (EMG), and the rating of perceived exertion (RPE). The farmers were interviewed as to possible and impossible work tasks and the ergonomic redesign measures taken to improve the work environment. The work tasks performed were mainly light or moderate work for the cardiorespiratory system according to mean HR (88-102 beats/min), the percentage of HR range (17–31% HRR), and the relative V02 (22–46% V02max). The mean activity of the trapezius muscles was 0.4-9% of the maximal voluntary contraction (%MVC). All the participants had work tasks they were unable to perform. They had made ergonomie redesign changes mainly to the tractor. This case study showed that some agricultural work tasks were possible for farmers with physical disabilities and that the physical strain associated with these tasks was mainly light or moderate. 相似文献