| 1. |
- Emsens, Willem-Jan, et al.
(författare)
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Competition for light as a bottleneck for endangered fen species : An introduction experiment
- 2018
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Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 220, s. 76-83
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Tidskriftsartikel (refereegranskat)abstract
- Many endangered plant species remain absent in rewetted, previously drained fens. We performed a 3-year introduction experiment with endangered fen species (9 Carex- and 6 bryophyte species) in 4 hydrologically restored fens to investigate which factors hamper establishment and survival. Carex species were introduced as adults and seedlings, mosses as gametophytes. Introductions were done on (initially) bare soil, which allowed us to exclude excessive competition for light during the first year. First year survival of the transplants was high in all fens (mean survival = 96%), indicating that there were no direct abiotic constraints on establishment. However, survival analysis revealed that a decrease in relative light intensity (RLI) at the soil surface during consecutive years (indicating an increase in biotic competition for light) drove high mortality rates in most species. As a result, overall final survival was lowest in the two most productive (low light) fens (mean survival = 38%), while most transplants persisted in the two less productive (high light) fens (mean survival = 79%). Taller and faster-growing Carex species were able to outgrow light limitation near the soil surface, and thus had a higher overall survivability than smaller and slower-growing species. Light limitation also drove the loss of 5 out of 6 bryophyte species. We conclude that both dispersal limitation and asymmetric competition for light may explain the lack and loss of small and endangered plant species in rewetted fens. A minimum empirical threshold of c. 30% relative light intensity near the soil surface is required for successful introduction.
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| 2. |
- Koschorreck, Matthias, et al.
(författare)
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Hidden treasures : Human-made aquatic ecosystems harbour unexplored opportunities
- 2020
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 49:2, s. 531-540
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Tidskriftsartikel (refereegranskat)abstract
- Artificial water bodies like ditches, fish ponds, weirs, reservoirs, fish ladders, and irrigation channels are usually constructed and managed to optimize their intended purposes. However, human-made aquatic systems also have unintended consequences on ecosystem services and biogeochemical cycles. Knowledge about their functioning and possible additional ecosystem services is poor, especially compared to natural ecosystems. A GIS analysis indicates that currently only similar to 10% of European surface waters are covered by the European Water Framework directive, and that a considerable fraction of the excluded systems are likely human-made aquatic systems. There is a clear mismatch between the high possible significance of human-made water bodies and their low representation in scientific research and policy. We propose a research agenda to build an inventory of human-made aquatic ecosystems, support and advance research to further our understanding of the role of these systems in local and global biogeochemical cycles as well as to identify other benefits for society. We stress the need for studies that aim to optimize management of human-made aquatic systems considering all their functions and to support programs designed to overcome barriers of the adoption of optimized management strategies.
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