Five-year carry-over effects in dune slack vegetation response to hydrology
Dune slacks are biodiverse seasonal wetlands within sand dune systems, strongly influenced by the dynamics of the local groundwater regime. Future climate predictions indicate strong adverse impact on the hydrology and therefore ecology of these wetland ecosystems. In this study we aimed to find the most appropriate hydrological and ecological indicators to summarise dune slack plant community responses to hydrology over multiple years. We evaluated 80 hydrological metrics (weighted and un-weighted median, mean, minimum, maximum, mean spring level, averaged over 1–8 year duration, and 5 additional 1-year metrics) against plant community re- sponses (variants of Ellenberg EbF moisture indicator). The data were drawn from 453 relev ́ees in 17 dune slacks, using permanent quadrats and co-located piezometers, set up in 2010 with vegetation monitoring repeated six times until 2019. Within our study we found a strong relationship between multiple hydrology metrics and the plant community response, but this displayed inter-annual variation with different patterns and correlations between years. The best performing hydrology metric was the unweighted 5-year average mean spring water level (MSL), linked to unweighted mean EbF using vascular plant species only. Maximum water level (MAX) also performed well, but MSL was preferred as MAX can be enhanced or truncated by topography leading to anomalies for individual slacks. MSL is also flexible to implement within manual monitoring programmes, which could be targeted to 3-months per year over the spring as a minimum requirement. These findings provide simpler metrics for site managers to monitor potential hydrology and vegetation responses to climate change.
Ecological Indicators 170 (2025) 113016
https://doi.org/10.1016/j.ecolind.2024.113016
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Foredune Dynamisation Manual
Authors: Bas Arens et al. 2024
Editorial staff: Albert Oost, Bas Arens & Sonja van der Graaf
Editorial staff English edition: Houston & Kenneth Pye
The manual is a must for all dune freaks - please take time to study it!
The pdf download you will find HERE.
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Infrastructure threatens biodiversity by squeezing sandy coasts
How human infrastructure threatens biodiversity by squeezing sandy coasts
Lansu, E. M., Fischman, H. S., Angelini, C., Hijner, N., Geelen, L., Groenendijk, D., ... & van der Heide, T. (2025). How human infrastructure threatens biodiversity by squeezing sandy coasts. Current Biology. https://doi.org/10.1016/j.cub.2025.09.027
Plant biodiversity increases nonlinearly with increasing undisturbed coastal width
Biodiversity reaches 75% of its max at 800 (US) to 1,800 m (the Netherlands) coastal width
Infrastructure squeezes 79% of US and 66% of Dutch coasts into much narrower strips
Management can partly mitigate infrastructure-driven biodiversity losses
Coastal dunes form valuable ecosystems that provide flood protection, drinking water, and high biodiversity worldwide. Although their functioning hinges on habitat zonation along >km-scale sea-to-land gradients, infrastructure development progressively squeezes natural dune ecosystems into a narrow strip. Yet it remains unknown how much undisturbed coastal width is required to support the diverse suites of habitats and species assemblages found in natural dune systems. Here, we investigate plant and habitat diversity in 614 plots along 47 sea-to-land transects in the southeastern USA and the Netherlands. We discover a linear relation between habitat diversity and species richness, indicating that species-rich dunes require diverse habitat assemblages. Moreover, we find that both plant and habitat diversity nonlinearly depend on coastal width, with cumulative plant diversity reaching ∼75% of its potential at 800 and 1,800 m widths in the southeastern USA and the Netherlands, respectively. Alarmingly, dune areas are narrower than these widths along 79% and 66% of southeastern USA and Dutch coastlines, highlighting that lack of space compromises biodiversity along the majority of coastlines. Finally, analyses of management measures along the transects reveal that strategic interventions can, at least in part, mitigate biodiversity losses from infrastructure encroachment. As coastal squeeze—i.e., combined losses from infrastructure and sea level rise—is a global phenomenon, our results suggest that it threatens biodiversity in dune ecosystems worldwide. We argue that the establishment or expansion of nature reserves may be vital for conserving wide dune systems and that targeted management measures can help maintain biodiversity where squeeze cannot be alleviated.
The aim of the current research is to develop this required knowledge for a renewed management strategy that offers space for natural degradation and construction processes that are essential for biodiversity, while coastal safety and other crucial functions, such as living, working, recreation and drinking water supply are safeguarded. For this, it is necessary to find out: (i) what the minimum width of a functioning coastal landscape mosaic is, depending on local conditions; (ii) which parts of the Dutch coastline are now wide enough, and how should these be managed; and (iii) whether broadening coasts that are too narrow by means of new landscape-scale replenishment methods can lead to recovery of natural erosion and restoration dynamics. In this, it is important to take into account the natural resilience of the coastal ecosystem against climate change and expected sea level rise and increase in storm intensity.
Along the Dutch coast, all habitat types occur at a dune zone width of less than 1500m, but 75% of the plant species are only found at an average dune width of about 1800m and 90% at a width of 2200(-5100)m. The differences in the soil environment between habitat types are usually caused by increasing soil development inland along a gradient of decreasing pH, and almost linearly increasing concentrations of nutrients. Differences within the soil environment of a habitat type are usually linked to variation in the concentration of alkali metals (e.g., Na and Ca). The wider a dune zone, the more diverse the soil environment, which in turn goes hand in hand with a higher plant species diversity. It is noticeable that, with a few exceptions, all habitats are nitrogen-limited.
When space along the coast is insufficient, strategic management (e.g. sod removal, mowing, grazing, etc...) can increase habitat diversity and increase species richness. To achieve, for example, 75% of the diversity potential, there is sufficient space along 57% of the sandy coast in the Wadden region, 43% of the Dutch coast and 10% of the Delta coast. Along the coasts where there is
insufficient space to achieve 75% of the diversity potential, an average of 0.6 km is needed to widen along the Wadden, 0.8 km in Holland and 2.3 km in the Delta. However, there is still too little experience in the Netherlands with mega replenishments to draw conclusions about their effectiveness in restoring long coastal gradients. And if 90% potential were to be achieved, an even greater broadening would be required, from 2200m (Wadden and Dutch coast) to 5100m (Delta).
Although parts of the Dutch coast offer sufficient space for a diverse dune landscape, there are also areas where space is lacking. Moreover, our research shows that even in areas with long dune landscape gradients, active dune management helps to maintain diversity. Thus, it is important to link the new knowledge about the minimum required width to insights about the establishment, disturbance-and-recovery dynamics of and resilience of key dune plant species and plant communities. Therefore, two additional field experiments were conducted. In the dynamic foredunes stress response of the dune-forming marram grass at two different life stages was compared. In the stabilized backdune, variation of disturbance-recovery dynamics of plant communities were assessed along a succession gradient. to gain a better understanding of how different dune plants and communities respond to disturbances.
Dunes, especially young dunes, are dynamic environments characterized by physical stress, frequent disturbances, and low plant species diversity. A characteristic species for young dunes is marram grass, which builds high dunes by capturing drifting sand.In marram grass, the stimulating effect of burial on growth differs between juvenile and mature plants. High sedimentation stress at the beach restricts establishment of young plants while ceasing sand dynamics further inland limits the recovery of mature marram grass. These age-dependent responses to burial stress constrain the habitat range of marram grass. In the backdune, reduced physical stress allows a wider range of plants to establish, increasing biodiversity. However, with ongoing succession and dune aging species diversity eventually decreases towards the landward end of the backdune gradient. Experiments show that survival of established marram grass on the beach is limited by erosion and burial as a result of sand dynamics, and that their growth here is actually enhanced by sand capture. Plants on higher, inland dunes show a good survival rate due to the lack of sand dynamics, but also no longer grow well due to a lack of capture of fresh sand. The more mature, stabilized back dunes show a greater diversity of plant species. Following After disturbances, plant communities with higher species diversity appear tend to recover better than communities with lower diversity.
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Abiotic and biotic drivers of soil microbial diversity in an intensively grazed natural ecosystem
Kinsbergen, D.T.P., Kooijman, A.M., Morriën, E. et al. Abiotic and biotic drivers of soil microbial diversity in an intensively grazed natural ecosystem. npj biodivers 4, 10 (2025). https://doi.org/10.1038/s44185-025-00081-x
Many ecosystems worldwide are threatened by anthropogenic causes, with high-intensity grazing by large herbivores as a significant risk factor for biodiversity. Although the drivers of α-diversity are well-studied for animal and plant communities, they are often overlooked for soil microbes, particularly in natural systems. We therefore used a novel innovative information-theoretic approach to structural equation model selection and multimodel path coefficient averaging to identify these drivers. Our findings show that abiotic soil characteristics, primarily soil pH, significantly shape the α-diversity of both bacteria and fungi. Biotic factors like vegetation Shannon diversity and aboveground biomass also significantly drive microbial α-diversity, especially for fungi. Our statistical approach adds robustness to our results and conclusions, offering valuable insights into the complex interactions shaping soil microbial communities in intensively grazed natural systems. These insights are crucial for developing more effective and comprehensive future ecosystem management and restoration strategies.