| 1. |
- Brunet, Jörg, et al.
(författare)
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Life-history traits explain rapid colonization of young post-agricultural forests by understory herbs
- 2012
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 278, s. 55-62
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Tidskriftsartikel (refereegranskat)abstract
- Large areas of agricultural land in Europe have been planted with broadleaved trees during the past decades. The aims of this study were to determine stand-scale colonization rates of European forest herbs in young (14-18 years old) post-agricultural broadleaved forest plantations, to analyze whether colonization rates were related to life-history traits and site characteristics, and to compare the results with studies in older post-agricultural forests. The colonization of herbaceous forest species was mapped in 16 young broadleaved forests and compared with their distribution in adjacent older forests in southern Sweden. Stand characteristics were analyzed in 32 paired sample plots. Colonization rates (m year(-1)) were calculated for 43 forest plant species. For 30 forest plant species we also compared current colonization rates with results from 30 to 75 year old stands. Colonization rates increased with maximum plant height and the potential dispersal distance, but were negatively related to diaspore mass and clonal spread. Soil, canopy and vegetation conditions in young forests were not significantly related to colonization rates. Nevertheless, young forests had higher soil pH and extractable phosphorus concentrations while soil organic matter content, basal area and canopy cover of the trees were higher in the adjacent older forests. Higher resource availability in young forests may favor competitive tall herbs over low-growing ancient forest plants. The comparison with colonization rates into older post-agricultural plantations revealed that while approximately half of the species had similar or lower rates, the other half had on average ca. ten times higher colonization rates in the present study, ranging from 3.0 to 11.5 m year-1 indicating the potential for relatively fast colonization by some forest plants. We conclude that planted post-agricultural forests can start to contribute to restoration of forest plant diversity shortly after canopy closure when located adjacent to older forests. However, many small forest plants, including those species which form extensive flower carpets characteristic of ancient forests, colonize young forests very slowly. Further research should focus on the development of restoration measures which facilitate the colonization process of ancient forest herbs. (C) 2012 Elsevier B.V. All rights reserved.
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| 2. |
- Brunet, Jörg, et al.
(författare)
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Pathogen induced disturbance and succession in temperate forests: Evidence from a 100-year data set in southern Sweden
- 2014
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Ingår i: Basic and Applied Ecology. - : Elsevier BV. - 1439-1791 .- 1618-0089. ; 15, s. 114-121
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Tidskriftsartikel (refereegranskat)abstract
- Major tree species arc declining in many temperate forests due to changing disturbance regimes, including invasive pests and pathogens. We examined the interaction of secondary succession and Dutch elm disease in the Swedish temperate forest reserve Dal by Soderskog, based on five tree surveys made between 1909 and 2011. The forest is characterized by the coexistence of four major European tree species: wych elm (Ulmm glabra), European ash (Fraxinus excelsior), European beech (Fagus sylvotica) and pedunculate oak (Quercus robur). After protection of the forest in 1918, lack of disturbance mainly favoured elm, while the oak population declined due to mortality of old oaks and lack of regeneration. Dutch elm disease has caused high and continuous elm mortality since 1988. As a result, increased light availability at the forest floor favoured abundant regeneration of ash, beech, and lately also oak. The recent arrival of an invasive fungal pathogen causing ash dieback may once again change the course of succession. Open space emerging from loss of elm and ash in forest reserves may be used by reserve managers in favour oak regeneration and biodiversity of semi-open woodlands once lost during succession to closed forest. We conclude that winners and losers change places as an effect of invasive pathogens, resulting in unexpected successions and both losses, id gains in valuable ecological niches and habitat structures in temperate broadleaf forests,
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| 3. |
- Olsson, Jesper, et al.
(författare)
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Energy efficient combination of sewage sludge treatment and hygenization after mesophilic digestion - Pilot study
- 2014
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 61, s. 587-590
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Tidskriftsartikel (refereegranskat)abstract
- Biogas production is probably the most feasible way of utilizing sewage sludge as energy source, simultaneously with nutrient recovery by recycling the biogas digestate (i.e. The residue) to arable land. However, the sludge commonly contains high amounts of human pathogenic bacteria excreted in faeces and urine. To use sludge as fertilizer on food producing land is therefore a controversial issue, partly because of the risk of spreading diseasecausing pathogens. The Swedish environment protection agency (SEPA) pre-approved two hygenization methods for the treatment of the sludge due to their positive effects on the sludge quality. One of them, conventional pasteurization (70 °C, 1 h), was investigated for its feasibility in Uppsala, Sweden, and it was found that the heat consumption was very high. The other method has the advantage of potentially increase the produced biogas. This hygenization method has been investigated in the present study through a pilot experiment where thickened mesophilic digested sludge is digested once more at thermophilic conditions (55 °C). The aim of the study was to investigate the possibility to develop this self-sufficient (in heat and electricity) hygenization method. The results showed an increase in the gas production from 430 dm3/kg VSin to 610 dm3/kg VSin by adding the thermophilic step. This increase gave an energy balance with an excess of both heat and electricity. Sludge hygenization was sufficient with the method and another important result is the significant decrease digestate volume.
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