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Survey of the wetland plants and aquatic macroinvertebrates in five starfruit ponds with notes on their management / Pond Action (Oxford, Royaume-Uni) (2000)  

Public Titre : Survey of the wetland plants and aquatic macroinvertebrates in five starfruit ponds with notes on their management Type de document : texte imprimé Auteurs : Pond Action (Oxford, Royaume-Uni), Éditeur scientifique Editeur : Oxford [Royaume-Uni] : Oxford Brookes University Année de publication : 2000 Importance : 17 p. Langues : Anglais (eng) Catégories : [ZG] Royaume-Uni [habitats/milieux] 2 - Milieux aquatiques non marins [habitats/milieux] ZH - Zones humides Mots-clés : plante humide  macro-invertébré  amphibien  diagnostic  espèce invasive  mesure de gestion Résumé : "This report describes the results of surveys of the wetland plants and aquatic macroinvertebrates of five starfruit ponds in Surrey and Buckinghamshire. The survey results showed that all the five ponds supported high quality plant and invertebrate communities. A summary of the species-richness of the ponds, and the occurrence of uncommon plants and invertebrates, is given in Table 1. In terms of their plant communities the ponds ranged in species richness from 22 – 32 species (excluding aliens) and all supported at least two local plant species. These results are similar to, or higher than, the average number of plant species expected from relatively unpolluted ponds in semi-natural areas. The ponds also supported relatively rich aquatic macro-invertebrate communities, and all had at least one Nationally Scarce invertebrate species. Amongst the five ponds, however, Chequers Pond and Half Penny ponds stood out as exceptional, both in their richness and the number of Nationally Scarce species recorded (see Table 1). The invasive plant New Zealand pigmyweed (Crassula helmsii) was present in all sites except Brimmer Pond. This included the Black Park Pond which was the only site known to support Damasonium alisma in the UK in 2000. Interestingly, although Crassula represents a major threat to the sustainability of starfruit at these sites, surveys showed that Crassula can be a good habitat for invertebrates, usually supporting as many or more species than other pond habitats. This is probably because the plant creates a complex underwater structure which is sufficiently dense to exclude major predators such as fish, amphibians and larger invertebrates. This finding is not an argument for maintaining Crassula in ponds, but suggests that the species may principally be a threat to plant rather than invertebrate communities. An overview of findings from surveys of starfruit ponds undertaken by Pond Action over the last five years suggests that a number of factors particularly characterise these ponds. This includes similarities in geology, water clarity, shape and traditional management. Floristically, the starfruit ponds often included plant species that are characteristic of mesotrophic waters including water-purslane (Lythrum portula), lesser marshwort (Apium inundatum), alternate water-milfoil (Myriophyllum alterniflorum), the stonewort Nitella flexilis agg. and lesser spearwort (Ranunculus flammula). The ponds also tended to support relatively abundant submerged plant communities, a factor often associated with good water quality. In comparison with most countryside ponds the starfruit sites’ invertebrate communities were particularly species-rich. Most were dominated by invertebrate species typical of eutrophic/base-rich conditions. However, all ponds except Coleshill also had species that are characteristic of more acid waters. The report concludes with a range of recommendations that suggest how starfruit sites might be created and sustained in future." (source : auteur) Type de publication : rapport d'études Référence biblio : Pond Action (éds), 2000 - Survey of the wetland plants and aquatic macroinvertebrates in five starfruit ponds with notes on their management. Oxford : Oxford Brookes University, 17 p. ID PMB : 65701 En ligne : http://www.naphillcommon.org.uk/Documents/Pond%20Action%202000%20-%20Naphill%20P [...] Format de la ressource électronique : document Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=65701

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