Clonal architecture and patch formation of Potamogeton perfoliatus L. in response to environmental conditions Susanne R. Wolfer Promotor: Prof.dr. M. Scheffer Hoogleraar Aquatische ecologie en waterkwaliteitsbeheer Departement Omgevingswetenschappen Wageningen Universiteit Co-promotoren: Dr.ir. E. H. van Nes Universitair docent, leerstoelgroep Aquatische ecologie en waterkwaliteitsbeheer Departement Omgevingswetenschappen Wageningen Universiteit PD Dr. D. Straile Limnological Institute University of Constance Promotiecommissie: Prof.dr. F. Berendse, Wageningen Universiteit Prof.dr. H.J. Lindeboom, Wageningen Universiteit Prof.dr. J.T.A. Verhoeven, Universiteit Utrecht Dr.ir. G.J. van Geest, Deltares, Utrecht Dr. M.S. van den Berg, Rijkswaterstaat, Waterdienst (RIZA), Lelystad Clonal architecture and patch formation of Potamogeton perfoliatus L. in response to environmental conditions Susanne R. Wolfer Proefschrift ter verkrijging van de graad van doctor op gezag van de rector magnificus van Wageningen Universiteit, Prof.dr. M.J. Kropff, in het openbaar te verdedigen op maandag 20 oktober 2008 des namiddags te vier uur in de Aula. Clonal architecture and patch formation of Potamogeton perfoliatus L. in response to environmental conditions / S.R. Wolfer Thesis Wageningen University - With ref. - With summary in Dutch ISBN 978-90-8585-211-7 Contents List of figures..............................................................................................................................6 List of tables ...............................................................................................................................7 Chapter 1 Introduction...............................................................................................................................9 Chapter 2 Lake and macrophyte characteristics..................................................................................... 15 Chapter 3 Spatio-temporal dynamics and plasticity of clonal architecture in Potamogeton perfoliatus... 23 Chapter 4 Density control in Potamogeton perfoliatus L and Potamogeton pectinatus L. ...................... 35 Chapter 5 Effect of sediment structure and nutrients on the growth of Potamogeton perfoliatus ........... 45 Chapter 6 To share or not to share - clonal integration in ramets of Potamogeton perfoliatus............... 55 Chapter 7 Modelling the clonal growth of the rhizomatous macrophyte Potamogeton perfoliatus ......... 65 Chapter 8 Synthesis and discussion....................................................................................................... 85 References ............................................................................................................................. 95 Summary ............................................................................................................................. 111 Samenvatting ....................................................................................................................... 113 Acknowledgement ................................................................................................................. 115 List of publications ................................................................................................................ 117 Curriculum vitae .................................................................................................................... 119 List of figures Fig. 1.1 Research at different scales ......................................................................................................................10 Fig. 2.1 Location of Lake Constance in Europe and geography of Lake Constance ..............................................15 Fig. 2.2 Lake Constance, satellite image................................................................................................................16 Fig. 2.3 Daily water levels at Konstanz (Upper Lake) for the years 1998 and 1999 ...............................................17 Fig. 2.4 P. perfoliatus (a) plant with 17 ramets and 8 branchings (b) turions..........................................................18 Fig. 2.5 Annual growth cycle of P. perfoliatus in Lake Constance ..........................................................................18 Fig. 2.6 P. perfoliatus patches, Lower Lake Constance..........................................................................................18 Fig. 2.7 (a) 3-D representation of distribution and shoot length (b) density (c) changes in patch growth ...............20 Fig. 2.8 Patch patterns and patch dynamics over a period of 3 years, north-west Reichenau. ..............................21 Fig. 3.1 Apical section of P. perfoliatus plant..........................................................................................................25 Fig. 3.2 Reconstructed spatio-temporal growth dynamics of P. perfoliatus at poor growth and rich growth site. ...27 Fig. 3.3 (a) Temporal development of ramet numbers and (b) average shoot length of P. perfoliatus. ..................28 Fig. 3.4 (a) Frequency distribution of spacer length (b) spacer length between primary and higher order shoots..28 Fig. 3.5 (a) Shoot growth rate and (b) rhizome growth rate per plant of P. perfoliatus. ..........................................29 Fig. 4.1 (a) Average number of ramets produced per site (b) average number of ramets recruited per initial shoot (c) average total dry weight production per initial shoot of P. perfoliatus...................................................37 Fig. 4.2 Average shoot, rhizome and root biomass allocation (%) of P. perfoliatus ................................................38 Fig. 4.3 (a) Average rhizome spacer length (b) relationship between total rhizome length and final number of ramets per site (c) average total rhizome length per plant of P. perfoliatus...............................................38 Fig. 4.4 Average number of rhizome branchings (a) per ramet (b) per plant of P. perfoliatus ................................39 Fig. 4.5 (a) Average number of tubers (b) fresh weight frequency distribution of tubers of P. pectinatus...............40 Fig. 5.1 Mesocosm, Limological Institute, University of Constance ........................................................................48 Fig. 5.2 Ramet number, shoot length, and total biomass of P. perfoliatus in unfertilized and fertilized quadrats ...49 Fig. 5.3 Biomass allocation and spacer length of P. perfoliatus without and with fertilization.................................50 Fig. 5.4 Average rhizome spacer length of P. perfoliatus in relation to position within rhizome..............................50 Fig. 5.5 Ramet number, ramet length and patch size of P. perfoliatus on unfertilized and fertilized sediment .......51 Fig. 6.1 (a) Aquarium (b) sketch of an experimental unit ........................................................................................57 Fig. 6.2 Total shoot biomass of both offspring ramets of P. perfoliatus in the 2-ramet versus 3-ramet system ......58 Fig. 6.3 Shoot biomass of the offspring ramets O1 and O2 in the different treatments ..........................................58 Fig. 6.4 Biomass ratio of second offspring and first offspring of P. perfoliatus grown in aquaria ............................59 Fig. 6.5 (a) Shoot (b) rhizome and (c) root allocation of 3-ramet system and 2-ramet system ...............................60 Fig. 6.6 Spacer length between offspring ramets in relation to first offspring shoot biomass. ................................60 Fig. 7.1 Schematic overview of the factors that determine the growth of each shoot .............................................69 Fig. 7.2 Scheme of the clonal growth of P. perfoliatus............................................................................................71 Fig. 7.3 Schematic representation of a clone and the transport of energy from the ramets to the turions ..............71 Fig. 7.4 Example of a generated pattern (clone growth during one year) ...............................................................73 Fig. 7.5 20 years run, (a) year 2009 (b) 1990 - 2010 ..............................................................................................74 Fig. 7.6 Relation between the mean number of ramets and biomass at day 249 ...................................................75 Fig. 7.7 Modelling results on the influence of branching probability after a simulation period of 20 years..............76 Fig. 7.8 Patch density and expansion in dependence to rhizome growth direction relative to the previous year....77 Fig. 7.9 Simulation of the response of P. perf. biomass to increasing and subsequently decreasing turbidity ......78 Fig. 7.10 Cluster analysis of the sensitivity parameters of the model .....................................................................79 Fig. 7.11 Time course of the relative sensitivity coefficients of various parameters on model outcomes ...............80 Fig. 8.1 Factors that influence patch characteristics...............................................................................................85 Fig. 8.2 Simplified responses of patch growth to light and nutrients as found in this study ....................................88 6 List of tables Tab. 1.1 Environmental parameters which influence plant growth and / or clonal architecture of submerged macrophytes.............................................................................................................................................11