| 1. |
- Hämäläinen, Aino, et al.
(författare)
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Low-productivity boreal forests have high conservation value for lichens
- 2020
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 57, s. 43-54
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Tidskriftsartikel (refereegranskat)abstract
- 1. Land set aside for preservation of biodiversity often has low productivity. As biodiversity generally increases with productivity, due to higher or more diverse availability of resources, this implies that some of the biodiversity may be left unprotected. Due to a lack of knowledge on the species diversity and conservation value of low-productivity habitats, the consequences of the biased allocation of low-productivity land for set-asides are unknown.2. We examined the conservation value of boreal low-productivity forests (potential tree growth <1 m(3) ha(-1) year(-1)) by comparing assemblages of tree- and deadwood-dwelling lichens and forest stand structure between productive and low-productivity forest stands. We surveyed 84 Scots pine-dominated stands in three regions in Sweden, each including four stand types: two productive (managed and unman-aged) and two low-productivity stands (on mires and on thin, rocky soils).3. Lichen species richness was the highest in low-productivity stands on thin soil, which had similar amounts and diversity of resources (living trees and dead wood) to productive unmanaged stands. Stands in low-productivity mires, which had low abundance of living trees and dead wood, hosted the lowest lichen richness. Lichen species composition differed among stand types, but none of them hosted unique species. The differences in both species richness and composition were more pronounced in northern than in southern Sweden, likely due to shorter history of intensive forestry.4. Synthesis and applications. Boreal low-productivity forests can have as high conservation value as productive forests, which should be reflected in conservation strategies. However, their value is far from uniform, and conservation planning should acknowledge this variation and not treat all low-productivity forests as a uniform group. Some types of low-productivity forest (e.g. on rocky soil) are more valuable than others (e.g. on mires), and should thus be prioritized in conservation. It is also important to consider the landscape context: low-productivity forests may have higher value in landscapes where high-productivity forests are highly influenced by forestry. Finally, although low-productivity forests can be valuable for some taxa, productive forests may still be important for other taxa.
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| 2. |
- Johansson, Victor, et al.
(författare)
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Epiphyte metapopulation persistence after drastic habitat decline and low tree regeneration: time-lags and effects of conservation actions
- 2013
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 50, s. 414-422
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Tidskriftsartikel (refereegranskat)abstract
- Old trees have declined in Europe due to agricultural intensification and forestry. For shade-intolerant epiphytic species occurring on old trees in semi-open landscapes, host tree numbers have further decreased because of shading by developing secondary woodland. Moreover, in this habitat, regeneration that could replace the extant old trees is low. This suggests that epiphytic species associated with old trees are declining. However, for species with low extinction rates, the decline may be slow and hard to elucidate. We investigated the persistence of five old-oak-associated epiphytic lichens with different traits by simulating metapopulation dynamics using Bayesian incidence function models for dynamic landscapes. With an oak-rich landscape as a reference, we investigated effects of (i) drastic habitat decline, (ii) conservation actions such as clearing around trees or increased regeneration rate, (iii) low tree regeneration and (iv) clearing and increased regeneration after 100years of low regeneration. After drastic habitat decline, the number of occupied trees continued to decrease, displaying long time-lags before reaching new metapopulation equilibriums. Lichen extinction risks increased with decreasing habitat and were highest for species that only colonise very old trees or have large dispersal propagules. In landscapes with low tree densities, conservation actions had only minor effects on lichen extinction risks. Low tree regeneration rates increased lichen extinction risks, but species declines were slow. Conservation actions that increased regeneration after 100years of low regeneration decreased the extinction risks to very low levels. Synthesis and applications. Due to low rates of local extinction, epiphytes display long time-lags to reach new equilibriums after habitat loss. Thus, we should expect ongoing declines in epiphyte metapopulations in landscapes where old trees have recently declined. Slow extinction gives an opportunity to improve persistence by conservation actions, but the success depends on species traits and the current density of old trees. In landscapes with many old but few young trees, epiphytes may persist if conservation actions quickly address the need to increase tree regeneration rates. The best conservation approach for long-term persistence of epiphytic lichens is to ensure regular tree regeneration in landscapes with a current high density of old trees.
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| 3. |
- Kärvemo, Simon, et al.
(författare)
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Beetle diversity in dead wood is lower in non-native than native tree species, especially those more distantly related to native species
- 2023
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 60, s. 170-180
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Tidskriftsartikel (refereegranskat)abstract
- Non-native tree species are widely used in forest plantations. This may have negative consequences for biodiversity. Hitherto, most studies have compared species diversity between native and non-native forest stands, which makes it difficult to separate the impact of tree species per se from stand characteristics. Our study, conducted in the south of Sweden, compares saproxylic beetle diversity across different nutritional groups, in dead wood of two native and four non-native tree species in a block design after one and three seasons. Such an approach allows analysis of the impact of non-native tree species per se. Mean species richness (+/- SD) per log was lower in non-native than in native tree species (non-native trees: lodgepole pine: 10.7 (+/- 5.3); Sitka spruce: 8.5 (+/- 4.3), Douglas fir: 7.1 (+/- 4.3), Japanese larch 9.4 (+/- 4.6); native trees: Norway spruce: 12.0 (+/- 6.0), Scots pine: 12.3 (+/- 5.2)). Sample-based rarefaction revealed that when only native tree species were pooled, the species richness was higher than for all tree species combined. The difference in species composition among tree species was strongly driven by bark and wood consumers in the first season, while for predators and fungivores, the differences were smaller. Species composition differed most in the first season. Dissimilarity in beetle species composition was positively correlated with phylogenetic distances of the tree species. Species richness was lower in non-native tree species that are only remotely related to native trees species. Of the studied non-native tree species, lodgepole pine was more closely related to native tree species and consistently harboured higher species richness. Synthesis and applications. Although non-native tree species also harbour saproxylic beetle communities, the use of non-native tree species, especially those only remotely related to native tree species, reduces local diversity of saproxylic beetles. Thus, for biodiversity conservation, an extensive use of non-native tree species is not recommended as this increases the risk of losing forest biodiversity, especially when they are only distantly related to native tree species.
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