Vegetation (Floating River Vegetation) - Office of Public Works

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Aquatic moss, Fontinalis antipyretica •Dark green moss growth completely submerged. •Circular domed moss shape. •Found in shallow slow flowing water. •Grows on gravel riverbeds or attached to submerged aggregate material. •Can tolerate shade but requires sunlight to penetrate the water surface. An overview of ecological characteristics associated with floating river vegetation recorded or sighted in Ireland has been compiled in Table 34. The similarity between plant spp. illustrates the similarity in leaf structure and habitat requirements. Although a probable identification can be made based on leaf, seed capsule and habitat an absolute identification requires a flower head. This was particularly evident with Ranunculus spp. in the absence of flowering structures during the course of the survey (section 3.2). 3.4 Life cycle of floating river vegetation To minimise the impact of channel maintenance on floating river vegetation it is essential that plant reproduction and colonisation be understood. By focusing on plant regeneration the nature and level of maintenance work required, the timing of the works and the appropriate environmental drainage maintenance systems can be selected to provide favourable habitats for floating river vegetation post maintenance works. Essentially two forms of reproduction can be used by plants, firstly seed production and secondly vegetative growth (Fig.16). Seed production is the preferred option for species survival and genetic diversity since it is the result of pollination by two different plants and is referred to as sexual reproduction. Asexual reproduction is the cloning of the mother plant by the production of spare roots from a growing section of the plant vegetation. The new root section breaks from the mother plant and develops as a new plant possessing the same genetic make-up as the initial plant. 24
Each form of reproduction requires very different environmental parameters, but both processes can be used to ensure plant survival. For sexual reproduction the flower is the most important structure. Flower colour is the primary attraction for pollen carrying insects and it is within the flower structure that the seed vesicles are formed. As the flower is the most delicate part of any plant the lower water levels of watercourses during summer months facilitates the floating of flowering structures on the water surface. Asexual reproduction for floating river vegetation is the optimisation of plant reproduction through an environmental adaptation. It is possible that low summer water levels trigger the development of rooting material observed on vegetation stems of Ranunculus and Milfoil species in late summer. Rapidly rising water level early autumn appear to serve two purposes, firstly the rising water levels cause the plant growth to break into smaller pieces with separate rooting systems and secondly that the faster flowing water carries the rooted sections further along the channel. Unlike seeds, which require germination prior to growing, the rooted plant material has an advantage that it can anchor and grow more quickly in rising water levels. Fig. 5 Floating river vegetation observed for Ranunculus species. White new shoots from stem vegetative reproduction (asexual reproduction) Seed head (sexual reproduction) 25
Page 1 and 2: ISSN 1649 - 9840 SERIES OF ECOLOGIC
Page 3 and 4: Foreword This Ecological Impact Ass
Page 5 and 6: Executive Summary Table of Contents
Page 7 and 8: 1.0 Introduction This study was com
Page 9 and 10: and fauna. The OPW has a multi-annu
Page 11 and 12: Currently twenty-one Special Areas
Page 13 and 14: 2.1.4 Lower River Shannon Special A
Page 15 and 16: 2.2.4 Site elevations within the Lo
Page 17 and 18: 2.3.4 Site integrity of the Lower R
Page 19 and 20: 3.0 Ecological Assessment of Water
Page 21 and 22: 3.2 Distribution and extent of floa
Page 23 and 24: 3.2.1 Floating river vegetation of
Page 25 and 26: aquatic moss. 3.2.3 Floating river
Page 27 and 28: 3.2.5 Floating river vegetation wit
Page 29: Starwort, Callitriche species •Ro
Page 33 and 34: prevented aquatic growth. Water lev
Page 35 and 36: G.densa was the dominant floating r
Page 37 and 38: 4.0 Description of maintenance oper
Page 39 and 40: consultation with the Foreman / Tec
Page 41 and 42: 4.3 River corridor water dynamics A
Page 43 and 44: Not shown in the above data set is
Page 45 and 46: 4.4 Physical, chemical and biologic
Page 47 and 48: •Survey watercourses to determine
Page 49 and 50: The primary riverbed substrate of w
Page 51 and 52: gravel require loosening assess the
Page 53 and 54: • Livestock should be restricted
Page 55 and 56: River Breagagh Winter 2006 River Br
Page 57 and 58: River Breagagh Winter 2006 Ranuncli
Page 59 and 60: 6.0 Conclusion and summary •Arter
Page 61 and 62: References •Blamey, M., Fritter,
Page 63 and 64: Appendix A - Special Areas of Conse
Page 65 and 66: Lower River Shannon Special Areas o
Page 67 and 68: Channel name Location coordinates E
Page 69 and 70: Appendix C - Habitat classification
Page 71 and 72: Lower River Shannon Special Area of
Page 73 and 74: Lough Corrib Special Area of Conser
Page 75 and 76: 7 Lower River Suir Special Area of
Page 77 and 78: C1 Lower River Shannon Special Area
Page 79 and 80: 6 C1/12/2 C1/18/1/1 /14/7/3 C/20/1
Page 81 and 82:
Appendix E - Physical parameters re
Page 83 and 84:
River Barrow and River Nore Special
Page 85 and 86:
Latin Name English Name Appendix F
Page 87 and 88:
Latin Name English Name Potamogeton
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Vegetation (Floating River Vegetation) - Office of Public Works

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