| 1. |
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| 2. |
- De Frenne, P., et al.
(författare)
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Atmospheric nitrogen deposition on petals enhances seed quality of the forest herb Anemone nemorosa
- 2018
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 20:3, s. 619-626
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Tidskriftsartikel (refereegranskat)abstract
- Elevated atmospheric input of nitrogen (N) is currently affecting plant biodiversity and ecosystem functioning. The growth and survival of numerous plant species is known to respond strongly to N fertilisation. Yet, few studies have assessed the effects of N deposition on seed quality and reproductive performance, which is an important life-history stage of plants. Here we address this knowledge gap by assessing the effects of atmospheric N deposition on seed quality of the ancient forest herb Anemone nemorosa using two complementary approaches. By taking advantage of the wide spatiotemporal variation in N deposition rates in pan-European temperate and boreal forests over 2years, we detected positive effects of N deposition on the N concentration (percentage N per unit seed mass, increased from 2.8% to 4.1%) and N content (total N mass per seed more than doubled) of A.nemorosa seeds. In a complementary experiment, we applied ammonium nitrate to aboveground plant tissues and the soil surface to determine whether dissolved N sources in precipitation could be incorporated into seeds. Although the addition of N to leaves and the soil surface had no effect, a concentrated N solution applied to petals during anthesis resulted in increased seed mass, seed N concentration and N content. Our results demonstrate that N deposition on the petals enhances bioaccumulation of N in the seeds of A.nemorosa. Enhanced atmospheric inputs of N can thus not only affect growth and population dynamics via root or canopy uptake, but can also influence seed quality and reproduction via intake through the inflorescences.
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| 3. |
- De Frenne, Pieter, et al.
(författare)
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Biological Flora of the British Isles : Milium effusum
- 2017
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 105:3, s. 839-858
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Tidskriftsartikel (refereegranskat)abstract
- 1. This account presents information on all aspects of the biology of Milium effusum L. (Wood Millet) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history, and conservation.2. The grass Milium effusum is a common species of mature woodland in central and southern England, but is less common in the wetter parts of northern England, Wales, Scotland and Ireland. Worldwide, the species is native to many temperate, boreal, subarctic and subalpine parts of the northern hemisphere: from eastern North America across most of Europe (excluding Mediterranean climates) to the Ural Mountains and Black Sea, extending eastwards to the Himalaya, Korea and Japan.3. Wood Millet is a shade-tolerant, relatively tall grass (up to 1.8 m) producing up to 700 caryopses per individual. It is characteristic of temperate deciduous woodland, but can also occur in other woodland and forest types and even in scrub, alpine meadows, along railways and roads, and on rocks. In woods, it is one of the most conspicuous plants of the herb layer in the early summer after the disappearance of spring flowering species. While the species is generally considered an ancient woodland indicator in England and western Europe, it is also known to colonize secondary, post-agricultural forests relatively rapidly in other areas such as Denmark, southern Sweden and Poland.4. The species has a wide amplitude in terms of soil acidity and nutrient availability, but predominantly grows on soils of intermediate soil fertility and soil pH and with high organic matter concentration. However, M. effusum can tolerate large quantities of tree-leaf litter on the forest floor and is able to grow on very acidic soils.5. Changes in land use, climate, densities of large herbivores and atmospheric deposition of nitrogen are having effects on populations of Wood Millet. Significant responses of the life-history traits and population characteristics have been detected in response to environmental variation and to experimental treatments of temperature, nutrients, light and acidity. In many of its habitats across its range, M. effusum is currently becoming more frequent. During the last century, its mean elevation of occurrence in upland areas of Europe has also increased by several hundreds of metres. Typically, management actions are directed towards the conservation of its main habitat type (e.g. ancient woodlands of the Milio-Fagetum association) rather than to the species specifically.
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| 4. |
- De Frenne, Pieter, et al.
(författare)
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Interregional variation in the floristic recovery of post-agricultural forests
- 2011
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 99:2, s. 600-609
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Tidskriftsartikel (refereegranskat)abstract
- 1. Worldwide, the floristic composition of temperate forests bears the imprint of past land use for decades to centuries as forests regrow on agricultural land. Many species, however, display significant interregional variation in their ability to (re)colonize post-agricultural forests. This variation in colonization across regions and the underlying factors remain largely unexplored. 2. We compiled data on 90 species and 812 species x study combinations from 18 studies across Europe that determined species' distribution patterns in ancient (i.e. continuously forested since the first available land use maps) and post-agricultural forests. The recovery rate (RR) of species in each landscape was quantified as the log-response ratio of the percentage occurrence in post-agricultural over ancient forest and related to the species-specific life-history traits and local (soil characteristics and light availability) and regional factors (landscape properties as habitat availability, time available for colonization, and climate). 3. For the herb species, we demonstrate a strong (interactive) effect of species' life-history traits and forest habitat availability on the RR of post-agricultural forest. In graminoids, however, none of the investigated variables were significantly related to the RR. 4. The better colonizing species that mainly belonged to the short-lived herbs group showed the largest interregional variability. Their recovery significantly increased with the amount of forest habitat within the landscape, whereas, surprisingly, the time available for colonization, climate, soil characteristics and light availability had no effect. 5. Synthesis. By analysing 18 independent studies across Europe, we clearly showed for the first time on a continental scale that the recovery of short-lived forest herbs increased with the forest habitat availability in the landscape. Small perennial forest herbs, however, were generally unsuccessful in colonizing post-agricultural forest even in relatively densely forested landscapes. Hence, our results stress the need to avoid ancient forest clearance to preserve the typical woodland flora.
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| 5. |
- De Frenne, Pieter, et al.
(författare)
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Plant movements and climate warming : intraspecific variation in growth responses to nonlocal soils
- 2014
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 202:2, s. 431-441
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Tidskriftsartikel (refereegranskat)abstract
- Most range shift predictions focus on the dispersal phase of the colonization process. Because moving populations experience increasingly dissimilar nonclimatic environmental conditions as they track climate warming, it is also critical to test how individuals originating from contrasting thermal environments can establish in nonlocal sites. We assess the intraspecific variation in growth responses to nonlocal soils by planting a widespread grass of deciduous forests (Milium effusum) into an experimental common garden using combinations of seeds and soil sampled in 22 sites across its distributional range, and reflecting movement scenarios of up to 1600km. Furthermore, to determine temperature and forest-structural effects, the plants and soils were experimentally warmed and shaded. We found significantly positive effects of the difference between the temperature of the sites of seed and soil collection on growth and seedling emergence rates. Migrant plants might thus encounter increasingly favourable soil conditions while tracking the isotherms towards currently colder' soils. These effects persisted under experimental warming. Rising temperatures and light availability generally enhanced plant performance. Our results suggest that abiotic and biotic soil characteristics can shape climate change-driven plant movements by affecting growth of nonlocal migrants, a mechanism which should be integrated into predictions of future range shifts.
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| 6. |
- De Pauw, Karen, et al.
(författare)
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Nutrient-demanding and thermophilous plants dominate urban forest-edge vegetation across temperate Europe
- 2024
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Ingår i: Journal of Vegetation Science. - 1100-9233 .- 1654-1103. ; 35:1
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Tidskriftsartikel (refereegranskat)abstract
- QuestionsForests are highly fragmented across the globe. For urban forests in particular, fragmentation increases the exposure to local warming caused by the urban heat island (UHI) effect. We here aim to quantify edge effects on herbaceous understorey vegetation in urban forests, and test whether these effects interact with forest structural complexity.LocationWe set up a pan-European study at the continental scale including six urban forests in Zurich, Paris, Katowice, Brussels, Bremen, and Stockholm.MethodsWe recorded understorey plant communities from the edge towards the interior of urban forests. Within each urban forest, we studied edge-to-interior gradients in paired stands with differing forest structural complexity. Community composition was analysed based on species specialism, life form, light, nutrient, acidity and disturbance indicator values and species' thermal niches.ResultsWe found that herbaceous communities at urban forest edges supported more generalists and forbs but fewer ferns than in forests' interiors. A buffered summer microclimate proved crucial for the presence of fern species. The edge communities contained more thermophilous, disturbance-tolerant, nutrient-demanding and basiphilous plant species, a pattern strongly confirmed by corresponding edge-to-interior gradients in microclimate, soil and light conditions in the understorey. Additionally, plots with a lower canopy cover and higher light availability supported higher numbers of both generalists and forest specialists. Even though no significant interactions were found between the edge distance and forest structural complexity, opposing additive effects indicated that a dense canopy can be used to buffer negative edge effects.ConclusionThe urban environment poses a multifaceted filter on understorey plant communities which contributes to significant differences in community composition between urban forest edges and interiors. For urban biodiversity conservation and the buffering of edge effects, it will be key to maintain dense canopies near urban forest edges. The urban environment poses a multifaceted filter on understorey plant communities which contributes to significant differences in community composition between urban forest edges and interiors. For urban biodiversity conservation and the buffering of edge effects, it will be key to maintain dense canopies near urban forest edges.image
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| 7. |
- De Pauw, Karen, et al.
(författare)
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Taxonomic, phylogenetic and functional diversity of understorey plants respond differently to environmental conditions in European forest edges
- 2021
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 109:7, s. 2629-2648
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Tidskriftsartikel (refereegranskat)abstract
- Forest biodiversity world-wide is affected by climate change, habitat loss and fragmentation, and today 20% of the forest area is located within 100 m of a forest edge. Still, forest edges harbour a substantial amount of terrestrial biodiversity, especially in the understorey. The functional and phylogenetic diversity of forest edges have never been studied simultaneously at a continental scale, in spite of their importance for the forests' functioning and for communities' resilience to future change.We assessed nine metrics of taxonomic, phylogenetic and functional diversity of understorey plant communities in 225 plots spread along edge-to-interior gradients in deciduous forests across Europe. We then derived the relative effects and importance of edaphic, stand and landscape conditions on the diversity metrics.Here, we show that taxonomic, phylogenetic and functional diversity metrics respond differently to environmental conditions. We report an increase in functional diversity in plots with stronger microclimatic buffering, in spite of their lower taxonomic species richness. Additionally, we found increased taxonomic species richness at the forest edge, but in forests with intermediate and high openness, these communities had decreased phylogenetic diversity.Functional and phylogenetic diversity revealed complementary and important insights in community assembly mechanisms. Several environmental filters were identified as potential drivers of the patterns, such as a colder macroclimate and less buffered microclimate for functional diversity. For phylogenetic diversity, edaphic conditions were more important. Interestingly, plots with lower soil pH had decreased taxonomic species richness, but led to increased phylogenetic diversity, challenging the phylogenetic niche conservatism concept.Synthesis. Taxonomic, phylogenetic and functional diversity of understorey communities in forest edges respond differently to environmental conditions, providing insight into different community assembly mechanisms and their interactions. Therefore, it is important to look beyond species richness with phylogenetic and functional diversity approaches when focusing on forest understorey biodiversity.
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| 8. |
- De Pauw, Karen, et al.
(författare)
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The urban heat island accelerates litter decomposition through microclimatic warming in temperate urban forests
- 2024
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Ingår i: Urban Ecosystems. - 1083-8155 .- 1573-1642.
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Tidskriftsartikel (refereegranskat)abstract
- Forests worldwide are experiencing fragmentation, with especially important consequences for ecosystems bordering urbanized areas. Urban forests are exposed to local warming due to the urban heat island which affects their biodiversity and ecosystem functioning. A key ecosystem function affecting carbon and nutrient cycling in forests is litter decomposition, a process driven by the local microclimate. Thus, our aim was to clarify the impact of the urban heat island on litter decomposition in urban forests. We studied soil microclimate and litter decomposition in six urban forests across Europe and along local gradients from the urban forest edge to the interior. To quantify decomposition independent from local forest composition and litter quality, we used standardized green tea and rooibos tea litterbags. We determined the role of the soil microclimate and other environmental drivers for litter decomposition. Secondly, we assessed effects of edge proximity and landscape context on the soil microclimate. Soil characteristics were only driving green tea and not rooibos tea decomposition. On the contrary, higher soil temperatures resulted in faster rates of litter decomposition for both green and rooibos tea and were related to the proximity to the forest edge and the proportion of built-up area in the landscape. Via structural equation modelling we detected cascading effects of the urban heat island on litter decomposition. Such changes in litter decomposition have the potential to alter the soil food web, nutrient cycling and carbon drawdown in urban forests, and could result in significant interactions between urbanisation and ongoing climate change.
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| 9. |
- De Pauw, Karen, et al.
(författare)
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Urban forest microclimates across temperate Europe are shaped by deep edge effects and forest structure
- 2023
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Ingår i: Agricultural and Forest Meteorology. - 0168-1923 .- 1873-2240. ; 341
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Tidskriftsartikel (refereegranskat)abstract
- The urban heat island (UHI) causes strong warming of cities and their urban forests worldwide. Especially urban forest edges are strongly exposed to the UHI effect, which could impact urban forest biodiversity and functioning. However, it is not known to what extent the UHI effect alters edge-to-interior microclimatic gradients within urban forests and whether this depends on the forests' structure.Here we quantified gradients of air temperature, relative air humidity and vapour pressure deficits (VPD) along urban forest edge-to-interior transects with contrasting stand structures in six major cities across Europe. We performed continuous hourly microclimate measurements for two consecutive years and analysed the magnitude and depth of edge effects, as well as forest structural drivers of microclimatic variation.Compared to edge studies in rural temperate forests, we found that edge effects reached deeper into urban forests, at least up to 50 m. Throughout the year, urban forest edges were warmer and drier compared to forest interiors, with the largest differences occurring during summer and daytime. Not only maximum, but also mean and minimum temperatures were higher at the urban forest edge up to large edge distances (at least 85 m). Denser forests with a higher plant area index buffered high air temperatures and VPDs from spring to autumn.We conclude that urban forest edges are unique ecotones with specific microclimates shaped by the UHI effect. Both forest edges and interiors showed increased buffering capacities with higher forest canopy density. We advocate for the conservation and expansion of urban forests which can buffer increasingly frequent and intense climate extremes. To this end, urban forest managers are encouraged to aim for multi-layered dense forest canopies and consider edge buffer zones of at least 50 m wide.
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| 10. |
- De Schuyter, Wim, et al.
(författare)
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Declining potential nectar production of the herb layer in temperate forests under global change
- 2024
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Ingår i: Journal of Ecology. - 0022-0477 .- 1365-2745. ; 112:4, s. 832-847
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Tidskriftsartikel (refereegranskat)abstract
- Wild pollinators are crucial for ecosystem functioning and human food production and often rely on floral resources provided by different (semi-) natural ecosystems for survival. Yet, the role of European forests, and especially the European forest herb layer, as a potential provider of floral resources for pollinators has scarcely been quantified.In this study, we measured the potential nectar production (PNP) of the forest herb layer using resurvey data across 3326 plots in temperate forests in Europe, with an average time interval of 41 years between both surveys in order to assess (i) the importance of the forest herb layer in providing nectar for wild pollinators, (ii) the intra-annual variation of PNP, (iii) the overall change in PNP between survey periods and (iv) the change in intra-annual variation of PNP between survey periods. The PNP estimates nectar availability based on the relative cover of different plant species in the forest herb layer. Although PNP overestimates actual nectar production, relative differences amongst plots provide a valid and informative way to analyse differences across time and space.Our results show that the forest herb layer has a large potential for providing nectar for wild pollinator communities, which is greatest in spring, with an average PNP of almost 16 g sugar/m2/year. However, this potential has drastically declined (mean plot-level decline >24%).Change in light availability, associated with shifts in canopy structure and canopy composition, is the key driver of temporal PNP changes.Synthesis. Our study shows that if management activities are carefully planned to sustain nectar-producing plant species for wild pollinators, European forest herb layers and European forests as a whole can play key roles in sustaining wild pollinator populations.
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