@article {Emsens:2017:0021-8901:1755,
title = "Restoration of endangered fen communities: the ambiguity of ironphosphorus binding and phosphorus limitation",
journal = "Journal of Applied Ecology",
parent_itemid = "infobike://bsc/jappl",
publishercode ="bp",
year = "2017",
volume = "54",
number = "6",
publication date ="2017-12-01T00:00:00",
pages = "1755-1764",
itemtype = "ARTICLE",
issn = "0021-8901",
eissn = "1365-2664",
url = "https://www.ingentaconnect.com/content/bsc/jappl/2017/00000054/00000006/art00016",
doi = "doi:10.1111/1365-2664.12915",
keyword = "wetlands, biodiversity, red list, water levels, phosphorus, nutrient limitation, eutrophication, iron, fen restoration, iron chemistry",
author = "Emsens, W.J. and Emsens, W.J. and Emsens, W.J. and Emsens, W.J. and Aggenbach, C.J.S. and Aggenbach, C.J.S. and Aggenbach, C.J.S. and Aggenbach, C.J.S. and Smolders, A.J.P. and Smolders, A.J.P. and Smolders, A.J.P. and Smolders, A.J.P. and Zak, D. and Zak, D. and Zak, D. and Zak, D. and van Diggelen, R. and van Diggelen, R. and van Diggelen, R. and van Diggelen, R.",
abstract = " Low phosphorus (P) availability limits plant biomass production in fens, which is a prerequisite for the persistence of many endangered plant species. We hypothesized that P limitation is linked
to soil iron (Fe) content and soil Fe:P ratios as iron compounds provide binding sites for dissolved P, presumably reducing P availability to plants. We sampled 30 fens in a transEuropean field survey to determine how soil Fe pools relate
to pools of P and Febound P, and we measured vegetation P uptake and N:P ratio to assess where P limitation occurs. Next, we determined P uptake by Carex rostrata in experimental fen mesocosms to investigate interactive effects of soil Fe and P pools (and fractions)
and water levels (drained or rewetted). The field survey revealed that soil P pools correlate positively with soil Fe pools, regardless of fen degradation level, location or sampling depth. Moreover, soil Fe and P pools correlated positively with P uptake by
the vegetation and negatively with vegetation N:P ratios. Generally, N:P ratios dropped below 10gg1 whenever thresholds of 15mmolFeL1 soil and 3\textperiodcentered3mmolPL1 soil
were exceeded. Endangered fen species mainly thrived in Fe (and thus P) poor fens. The mesocosm experiment further showed that interactions between water levels and P pools determined plant P uptake: although fen rewetting led to an overall
increase in P uptake, plants that had grown on drained Ferich soils with large acidextractable P pools (>1\textperiodcentered6mmol PacidL1) could still sequester large quantities of P. Soil Fe:P ratio had no effect on P uptake.
Synthesis and applications. Our findings have important implications for the management and restoration of endangered fen communities. We demonstrated the existence of an ironphosphorus (FeP) binding ambiguity in fens: large Fe pools trap
mobile P, thereby enhancing overall P availability to plants rather than diminishing it. For P limitation, we suggest an empirical threshold of 1 soil, which is mainly found in Fepoor fens. Restoring fens by rewetting increases the relative
availability of P and may not always result in favourable conditions for endangered fen communities. Rewetting of drained fens is most likely to be successful if soil P and Fe pools are well below 3\textperiodcentered3 and 15mmolL1 respectively. ",
}