Cabanis M

Corenblit D

Garreau A

Garófano-Gómez V

Hortobágyi B

Otto T

Roussel E

Steiger J

Vidal V

Voldoire O

Pioneer riparian trees which establish in river active tracts on gravel bars enhance fine sediment retention during high flows within their stands and in their lee side, forming obstacle marks. Fine sediment retention can be accompanied by deposition of seeds transported by water dispersal, i.e. by hydrochory. We tested the hypothesis that pioneer riparian trees significantly control seed deposition on gravel bars by forming sediment obstacle marks. We described the seed bank structure and compared samples collected from obstacle marks and bare coarse-grained bar surfaces. At the surface (at 2 cm depth), seed abundance (N) and richness (S) (expressed as mean \ub1 sd) were significantly higher in areas directly affected by riparian trees, i.e. obstacle marks, (N: 693 \ub1 391; S: 17 \ub1 3) than in bare surfaces (N: 334 \ub1 371; S: 13 \ub1 5). Surface and sub-surface (at 20 cm depth) samples were also significantly different, with the sub-surface samples almost devoid of seeds (respectively N: 514 \ub1 413; S: 15 \ub1 5 and N: 3 \ub1 6; S: 1 \ub1 2). These results suggest a biogeomorphic feedback between sediment and associated seed retention mediated by hydrochory, vegetation growth and local seed dispersal mediated by barochory. Such feedback may improve plant diversity resilience on gravel alluvial bars of high-energy rivers

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Seed Retention by Pioneer Trees Enhances Plant Diversity Resilience on Gravel Bars: Observations from the River Allier, France

Seed Retention by Pioneer Trees Enhances Plant Diversity Resilience on Gravel Bars: Observations from the River Allier, France

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