Biological Flora of Central Europe: Chondrilla chondrilloides (Ard.) H. Karst

Woellner, Romy; Bräuchler, Christian; Kollmann, Johannes; Wagner, Thomas C.

doi:10.1016/j.ppees.2021.125657

Cited by 5 publications

(5 citation statements)

References 26 publications

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“…The results re ect today's distribution of the species, where a natural and large metapopulation of C. chondrilloides is found only in the Lech riverscape. In the Wallgau riverscape, a small population was reintroduced in 2018 and initially increased on the local patch but did not colonize neighboring patches (Woellner et al, 2021) and in the Lenggries riverscape the species is missing.…”

Section: Discussionmentioning

confidence: 99%

“…For this purpose, many typical plant species produce a high number of wind-dispersed seeds, germinating and developing into seedlings quickly under favorable conditions (Egger et al, 2022;Müller & Scharm, 2001). The dispersal distance of such species is often comparatively small (Bill et al, 1999;Woellner, Bräuchler, et al, 2022), but under natural conditions, suitable habitat patches mainly occur close to each other. Long-distance dispersal is rare and infrequent (Imbert & Lefèvre, 2003;Nathan et al, 2008;Soons, 2006) as only a tiny fraction of seed lands on the river are transported over longer distances during ood events.…”

Section: Introductionmentioning

confidence: 99%

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A new set of metrics to quantify the colonization potential of riverscapes by wind-dispersed plant species

Wagner

Wöllner

2023

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Quantifying the potential of a braided riverscape to be colonized by a plant species is important for assessing the ecological state of the river and provides an important basis for nature conservation planning and the implementation of restoration measures. Common landscape and river connectivity indices are largely unsuitable for describing the situation for the mostly wind-dispersed plant species. We aim to provide a set of comparable metrics that allows the quantification of the colonization potential of riverscapes at the patch and riverscape level. We define and describe a set of cell-based, spatially explicit measures that can easily be implemented. We demonstrate their application using two typical plant species and three riverscapes with different habitat configurations as examples. Our metrics consider shape, size and the spatial configuration of habitat patches, along with the dispersal characteristics of the respective species. The metrics provide a linear, balanced, and realistic representation of the colonization potential at the cell, patch, and riverscape levels. The results are comparable between different riverscapes and species and can easily be extended and used for further modeling. The metrics provide a valuable tool for the planning and evaluation of conservation, restoration, and reintroduction measures and close the gap between simple habitat availability analyses and large-scale terrestrial connectivity indices.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A new set of metrics to quantify the colonization potential of riverscapes by wind-dispersed plant species

Wagner

Wöllner

2023

Preprint

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“…The reduced gravel bar area has also serious implications for the ecosystems of regulated rivers. In the study region, many riparian pioneer species, such as the plants Chondrilla chondrilloides and Myricaria germanica , Formica selysi (ant) or Bryodemella tuberculata (grasshopper), and even a number of gravel‐breeding bird species—all of them endangered and red‐listed today (Reich, 1991; Woellner et al, 2019, 2021)—rely on the open and frequently disturbed gravel habitats. In many cases, the remaining gravel bars are fixed and immobilized, and affected by shrub encroachment, and thus do not provide the historical habitat quality of a natural alpine river.…”

Section: Discussionmentioning

confidence: 99%

“…Several aquatic and terrestrial animal and plant specialists depend on dynamic gravel bars with frequent flooding and desiccation. Consequently, the reduction in the amount of gravel area and hence habitat diversity causes a dramatic decrease in the abundance of floodplain species, including gravel spawning fish (Kondolf, 1997), benthic invertebrates, ground beetles (Langhans & Tockner, 2014), and pioneer plants (Sitzia et al, 2016; Woellner, Bräuchler, Kollmann, & Wagner, 2021; Woellner, Müller, Reich, Wagner, & Kollmann, 2019). Moreover, less frequent flooding, lower groundwater levels, and a modified sediment composition (Kondolf, 1997) result in rapid succession (Bravard et al, 1997), thus, further degrading the quality of the remaining habitats, and also negatively affecting the resilience of rivers and their communities under climate change.…”

Section: Introductionmentioning

confidence: 99%

Spatio‐temporal patterns in degradation and restoration of gravel bars along Alpine rivers

Woellner

Wagner

Crabot

et al. 2022

River Research & Apps

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Braided reaches were common along near‐natural Alpine rivers, and the associated habitat dynamics supported plant and animal species specialized on early‐successional stages. The extensive riparian zones could mitigate climate change by absorbing floods and by retaining water during droughts. Human impacts largely reduced active river corridors through altered discharge and construction of dykes, while recent restoration projects aim at increasing river dynamics. The causes and consequences of Alpine river degradation are well understood, but there are only few quantitative studies on floodplain degradation and restoration. Thus, we have reconstructed historical changes of gravel bars along five Alpine rivers (Iller, Inn, Isar, Lech, and Wertach) in Southern Germany in the period 1808–2009, based on historical maps and aerial images. We found losses of >90% in gravel bar area along these rivers since the mid‐19th century. The decline was caused by a reduction of the active river corridor and by ongoing succession of the remaining open habitats. Within the past 30 years, at the Isar River, restoration measures were realized with the aim to widen the active river corridor and to recreate gravel bars. In four restored reaches, we found that 5% of the historical gravel bar area recovered, and that the proportion of restored gravel bar area was highest after intermediate flooding. We conclude that the active river corridors of German Alpine rivers are almost completely lost, and that more extensive restoration needs to be done to preserve the habitat dynamics and biodiversity of these systems, and to adapt Alpine rivers to climate change.

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“…Within a reach, stream power and sediments are more or less constant and determine braiding intensity, while discharge and vegetation vary over years and thus are decisive for habitat availability. Together with floods and more small-scale inundation of the riparian zone, these processes maintain a diverse, constantly changing mosaic of more or less open habitats that support metapopulations of specialized animal and plant species (e.g., Woellner, Bräuchler, et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Biogeomorphological floodplain dynamics along a degradation gradient of an Alpine river

Wagner,

Woellner,

Kloska

et al. 2024

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Channel migration, furcation, and vegetation succession are characteristic processes of braided gravel rivers in Alpine regions. These are associated with a frequent turnover of large parts of the active floodplain. However, more than one century of river regulation has reduced or destroyed most of these ecosystem dynamics. More recently, there have been attempts to restore at least some sections of degraded rivers, while there is little monitoring of the biogeomorphological dynamics of such rivers. Thus, we did a four‐year analysis of four representative sections of the upper River Isar in Southern Germany differing in their degree of naturalness. Dynamics of channels, gravel bars, and vegetation were recorded by drone images, and braiding and gravel indices were calculated. When comparing the near‐natural, semi‐natural, degraded or restored sections, there was a gradient of decreasing channel migration, gravel bank expansion, and bank erosion due to a reduced turnover frequency. Biogeomorphological variation among years correlated with log peak discharge within the four sections. In addition, the cover and height growth of vegetation increased with river degradation, and channel migration was positively related to the braiding index. The total turnover of the active river corridor and of the vegetation were positively correlated with log peak discharge within the four sections. The floodplain dynamics of the restored section were improved compared to the degraded section but did not reach a near‐natural state. Thus, Alpine river sections with contrasting degrees of naturalness differ in terms of habitat turnover and vegetation succession, and these characteristics can only partially be restored by local measures.

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Biological Flora of Central Europe: Chondrilla chondrilloides (Ard.) H. Karst

Cited by 5 publications

References 26 publications

A new set of metrics to quantify the colonization potential of riverscapes by wind-dispersed plant species

A new set of metrics to quantify the colonization potential of riverscapes by wind-dispersed plant species

Spatio‐temporal patterns in degradation and restoration of gravel bars along Alpine rivers

Biogeomorphological floodplain dynamics along a degradation gradient of an Alpine river

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