| 1. |
- Bakx, Tristan R.M., et al.
(författare)
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Farmland birds occupying forest clear-cuts respond to both local and landscape features
- 2020
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127. ; 478
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Tidskriftsartikel (refereegranskat)abstract
- Agricultural landscapes have changed fast in Europe, which has led to steep declines in farmland biodiversity. While this has differentially impacted “farmland species”, some of these seem to be able to use alternative man-made open habitats in forests, such as forest clear-cuts and powerline rights-of-way. We investigated the use of clear-cuts by two historically declining farmland birds, the Yellowhammer (Emberiza citrinella) and the Red-backed Shrike (Lanius collurio), to determine both local and landscape habitat characteristics of clear-cuts used for breeding. Among 101 clear-cuts visited in Scania, southern Sweden, 27% were occupied by Yellowhammers and 12% by Red-backed Shrikes. Yellowhammer occurrence in clear-cuts was positively related to local spruce cover (the planted tree species). There was also an interaction between clear-cut size and the proportion of farmland in the landscape, such that the positive effect of the proportion of farmland nearby was stronger for larger clear-cuts. Red-backed Shrike occurrence was positively related to clear-cut size and the local presence of piles of forest residues (tops and branches). The relation between occurrence and the proportion of clear-cuts in the landscape was positive for small clear-cuts and negative for larger ones. Yellowhammers and Red-backed shrikes are affected by both the local habitat structure in the clearcut and on the composition of the surrounding landscape, most likely because they use the clear-cut for nesting and the surroundings as complementary feeding habitat. To what extent clear-cuts as complementary breeding habitat to farmland may contribute to the conservation of Yellowhammers and Red-backed shrikes, as well as other farmland birds, is a promising path for future investigations.
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| 2. |
- Pejchar, Liba, et al.
(författare)
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Net Effects of Birds in Agroecosystems
- 2018
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Ingår i: BioScience. - 0006-3568. ; 68:11, s. 896-904
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Tidskriftsartikel (refereegranskat)abstract
- Incorporating both ecosystem services and disservices into land-use decisions is essential for meeting conservation and livelihood goals. We discuss the merits and challenges of this concept, termed net effects, for birds in agroecosystems. Although birds have widely documented impacts on agriculture (e.g., pest control, crop damage), the net effects of such activities are rarely quantified. This could be attributed to the complexity of measuring direct and indirect trophic interactions, and the necessity of cross-disciplinary collaboration to value biophysical outcomes in economic and other relevant terms. We suggest that the direction and magnitude of net effects is driven by biotic, farm-level and landscape factors. These factors, some within and others beyond farmer control, interact in potentially predictable ways. We propose a framework for making policy decisions about farming practices and land-use planning informed by net effects to help farmers and society achieve positive outcomes for biodiversity and agricultural production.
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| 3. |
- Ram, Dafne
(författare)
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Birds and butterflies at the forest-farmland interface
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Land-use change is one of the greatest threats to biodiversity. Through intensification of land-use, the agricultural landscape has become more homogenous and a result, many species associated with traditional farmland or other semi-natural open habitats have declined. To be able to improve biodiversity conservation we need to be able to track components of biodiversity and understand how they respond to environmental changes. Biodiversity indicators can be very helpful in tracking such changes. However, species categorized as an indicator species for a certain habitat, might not exclusively occur in that habitat. In an intensely used landscape, with low amounts of natural and semi-natural habitats, some species may turn to use anthropogenic habitats such as forest clear-cuts. While these habitats might not categorize as grassland or farmland in our eyes, in some cases they seem to provide similar resources to farmland and grassland species. In this thesis, we compared multi-species indicators of farmland, grassland and forest butterflies and birds (Paper I) and found that indicators based on different taxa may send different signals even though they are based on the same habitat. Additionally, national trends might mask regional variation in trends. The literature review (Paper II) showed that farmland and grassland birds and butterflies do indeed occur on clear-cuts but the exact conditions that they need are often unclear. We then further explored the occurrence patterns of birds and butterflies in forest-clear cuts (Paper III and IV). We found that bird communities on clear-cuts changes with clear-cut age, size, vegetation height, the proportion of farmland in the near surroundings, and region. 10 out of 15 farmland bird indicator species occur on clear-cuts. They responded differently to environmental variables suggesting some might use clear-cuts as primary habitat in some regions and some might use clear-cuts more as complementary habitat while still depending on farmland in the surroundings. Clear-cuts are, however, not suitable for all farmland birds, most likely for reasons related to nesting sites, food, and predation risk.Butterfly communities on clear-cuts differ between the two surveyed counties as well as with clear-cut age and the proportion of open habitat and broadleaf forest in the surrounding landscape. Of the 20 farmland and grassland butterfly indicator species, 17 were observed on clear-cuts. While birds mostly responded to open habitat within a 200 m buffer of the clear-cuts, the butterflies more strongly responded to the larger scale 5 km landscape variables. Farmland bird abundance was often positively affected by clear-cut size while farmland and grassland butterflies, in the clear-cut centroids, were negatively affected by clear-cut size. This effect on butterflies was not seen in the edge of the clear-cuts, and this might indicate that butterflies either have a preference for the edges of the clear-cuts or use these lines in the landscape for orientation.While further studies are needed to expand our knowledge on how species, not least the currently declining grassland and farmland species, use these habitats to form more detailed management advice, the results in this thesis emphasize the importance of a landscape scale approach to conservation of both birds and butterflies. Forest clear-cuts could contribute to a green infrastructure for farmland and grassland birds and butterflies, however, the negative effect of forest clear-cuts on forest biodiversity as well as the climate needs to be taken into account when making conservation decisions.
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| 4. |
- Ram, Dafne, et al.
(författare)
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Farmland birds on forest clear-cuts : Liked by some, avoided by others
- 2023
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127. ; 529
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Tidskriftsartikel (refereegranskat)abstract
- Many bird species typical to farmland have declined in numbers in recent decades. Some farmland bird species occur outside farmland in other open man-made habitats, such as forest clear-cuts. Given that in Sweden the total area of clear-cuts (5–6 %) almost equals that of farmland (8 %), clear-cuts have the potential to be an important habitat for some farmland birds. We investigated how bird community composition and species abundance on Swedish clear-cuts varied with geographical region, clear-cut characteristics and the surrounding landscape, with special focus on farmland species. Based on short visits in 2017–2019, we surveyed the occurrence of birds on 300 representative clear-cuts in Sweden, including six regions and 1300 km of latitude. We counted 1170 birds of 66 different species, including 10 out of 15 bird species in existing farmland bird indicators. Both bird community composition and species abundance varied with clear-cut size, age, vegetation height, region and proportion of nearby farmland, depending on species’ ecology. All six farmland species being proportionally common on clear-cuts are, when in farmland, dependent on residual habitats such as pastures and field borders with bushes and trees. In contrast, a third of the dedicated farmland species were scarce in clear-cuts, probably avoiding them because of predator-related avoidance of forest edges and/or a lack of suitable nest sites or food resources. To determine the full importance of forest clear-cuts for farmland species, and potentially make them more favourable for farmland birds, more studies are needed on the reproductive success on clear-cuts and which site features make them suitable habitat. This study did not determine the consequences of clear-cuts for forest birds across the forest cycle, consequences which needs to be balanced against any gains for farmland birds.
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| 5. |
- Ram, Dafne, et al.
(författare)
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Forest clear-cuts as habitat for farmland birds and butterflies
- 2020
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127. ; 473
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Forskningsöversikt (refereegranskat)abstract
- The intensification of agriculture has resulted in more homogeneous landscapes and declines of many species associated with farmland or other semi-natural open habitats. In parallel, forestry has also intensified causing declines in many species associated with old-growth forests. While intensive forestry negatively affects forest species, it inadvertently creates new habitats such as clear-cuts, which attracts some farmland species. To understand the potential of clear-cuts as alternative habitat for farmland species, we need to know what makes clear-cuts attractive and whether they are suitable for reproduction and survival. We reviewed literature on the occurrence of farmland birds and butterflies in forest clear-cuts and synthesise the current knowledge on factors and characteristics affecting their occurrence. Many farmland birds and butterflies do indeed use clear-cuts, and have been found in clear-cuts up to ten years after felling. Clear-cut characteristics of importance include age, size, retention structures, land-use history and landscape composition. However, direct measures of resource abundance such as food and hostplants are often lacking. In addition to the potential benefit of individual clear-cuts, the total clear-cut area in forested regions is often large. Together with the fact that clear-cuts may be occupied by farmland species for several years, the potential of clear-cuts as alternative habitat for farmland biodiversity is substantial. Clear-cuts with a history as meadows, the presence of species of conservation importance, or shorter distance to farmland could for example be motivations for focusing conservation efforts on farmland species instead of forest species. Gaining more knowledge on how farmland species use clear-cuts, and what characteristics they depend on, could help inform management guidelines. We are no advocates for forest clear-cuts, but given their ubiquity in forested landscapes, the potential of clear-cuts as alternative habitats for species suffering from loss of suitable farmland habitats is worth serious attention from a conservation perspective.
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| 6. |
- Ram, Dafne, et al.
(författare)
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Small changes in timing of breeding among subarctic passerines over a 32-year period
- 2019
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Ingår i: Ibis. - : John Wiley & Sons. - 0019-1019 .- 1474-919X. ; 161:4, s. 730-743
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Tidskriftsartikel (refereegranskat)abstract
- Many bird populations in temperate regions have advanced their timing of breeding in response to a warming climate in recent decades. However, long-term trends in temperature differ geographically and between seasons, and so do responses of local breeding populations. Data on breeding bird phenology from subarctic and arctic passerine populations are scarce, and relatively little data has been recorded in open-nesting species. We investigated the timing of breeding and its relationship to spring temperature of 14 mainly open-nesting passerine species in subarctic Swedish Lapland over a period of 32 years (1984-2015). We estimated timing of breeding from the progress of post-juvenile moult in mist-netted birds, a new method exploring the fact that the progress of post-juvenile moult correlates with age. Although there was a numerical tendency for earlier breeding in most species (on average -0.09 days/year), changes were statistically significant in only three species (by -0.16 to -0.23 days/year). These figures are relatively low compared with what has been found in other long-term studies but are similar to a few other studies in subarctic areas. Generally, annual hatching dates were negatively correlated with mean temperature in May. This correlation was stronger in long-distance than in short-distance migrants. Although annual temperatures at high northern latitudes have increased over recent decades, there was no long-term increase in mean temperature in May over the study period at this subarctic site. This is probably the main reason why there were only small long-term changes in hatching dates.
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| 7. |
- Ram, Dafne, et al.
(författare)
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What drives current population trends in forest birds – forest quantity, quality or climate? A large-scale analysis from northern Europe
- 2017
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 385, s. 177-188
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Tidskriftsartikel (refereegranskat)abstract
- Changes in forestry practices and on-going climate change may both have large impacts on forest bird populations. However, large-scale analyses of the effects of temporal changes in forest structure on forest bird numbers are largely lacking. We compared temporal trends from two Swedish nationwide long-term monitoring schemes, the Swedish Bird Survey (1998–2015) and the Swedish National Forestry Inventory (1983–2014), giving representative values for both forest and bird changes over an area of 35 million ha. Since 1998 the total area of middle-aged and mature forest increased by 6.4%. In parallel, several forest structures potentially beneficial to birds (dead wood, retention trees on clear cuts, multi-layer forests, old forest and broadleaved forest) increased somewhat in abundance, most likely as a result of legislation changes and increasing areas under forest certification schemes. Summer temperatures also increased, with warm summers dominating since 2002. In 1998–2015, the population sizes of 58 forest bird species on average increased, as did the number of species observed per route, with no general difference between forest specialists (16 species) and generalists (42 species). However, from around 2005, the positive trends in bird numbers and many forest structures have levelled out. An analysis of species population trends in relation to a measure of climate sensitivity (Species Temperature Index, STI) suggested that forest birds, just like Swedish birds in general, have indeed been affected by a warming climate. But given their STI, forest birds on average had more positive trends than non-forest birds, suggesting that other factors than climate have affected them positively. Strong candidate factors are the documented changes in forest quality and quantity. Whereas our data and analyses are correlational, and no firm conclusions on causality therefore can be drawn, it is reasonable to assume that the recent increases in forest quantity, forest quality, and summer temperatures, all have contributed to the general increase in forest bird numbers in Sweden. But the relative contribution of these driving forces remains to be determined. When it comes to the potentially positive effects of improving forest quality in terms of increases in old forest, stratification, retention trees and dead wood, it is noteworthy that many of the positive trends in forest structures since the mid-1990s seem to have ceased recently.
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