Robust tools are needed to prioritise the management of invasive non-native species

Three experiments were undertaken to investigate the influence of seed mixture on the establishment of a target grassland community on a site with high available phosphorus. In the first experiment autumn‐ and spring‐sown commercial seed mixtures were compared with seed harvested from a nature reserve with respect to their ability to produce an inundation grassland community similar to that described by the British National Vegetation Classification (NVC) as Agrostis stolonifera–Alopecurus geniculatus grassland (MG13). In the second experiment the composition and sowing rate of a commercial seed mixture were altered to investigate whether these factors were significant in the establishment of a sward similar to MG13. Similarly, in the third experiment the composition of a commercial seed mixture designed to achieve an alternative community, Cynosurus cristatus–Caltha palustris grassland (NVC code MG8), was sown. The vegetation resulting from each of these treatments was monitored with permanent quadrats for a 3‐year period, and the hydrological regime of each quadrat location was modeled and quantified. The results showed that seed mixture, timing of sowing, and seeding rate had an initial effect on the vegetation that established. However, by the third year of monitoring there were no significant differences between these treatments, and hydrological regime had become the most important factor in determining the distribution of species. The vegetation was less diverse than predicted from germination tests and decreased in diversity over the monitoring period. It is suggested that this may be a result of the hydrological regime being unsuitable for several of the sown species or due to the extremely high available phosphorus concentration in the soil. This study highlights the need to understand the soil and hydrological conditions of a site before choosing a target community and designing a seed mixture.

Estimations of waterbird herbivory at a newly created wetland, indicate that overwintering waterbirds have the potential to remove a large proportion of the above-ground macrophyte standing crop in the main lagoons. Observed lake state switching and changes in macrophyte species composition may have been linked, in part, to waterbird herbivory. Significant differences were observed in the distribution of certain species of waterbird between the lagoons, which may reflect food preferences. Between 30% and 50% of the herbivorous waterbird community utilised alternative on-site feeding areas over the winter period thus reducing the impact of grazing intensity in the larger open water areas. These results emphasise the advantages of incorporation of site heterogeneity, specifically distinct hydrological units, within the design of wetland creation schemes. Hypereutrophic conditions, with turbid water and dense filamentous algal blooms were experienced on the Reservoir Lagoon yet the lagoon supported high densities of overwintering birds (>100 individuals ha À1 ). This led to an alleviation of grazing pressure on other water bodies thereby promoting the development of macrophyte communities elsewhere on site. The need for work to provide a better understanding of critical thresholds of herbivory in determining community composition and abundance, and particularly the role of eutrophication in these processes is highlighted.

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