The effects of habitat fragmentation on niche requirements of the marsh fritillary, Euphydryas aurinia, (Rottemburg, 1775) on calcareous grasslands in southern UK

The marsh fritillary, Euphydryas aurinia, has declined greatly in distribution across its range within Europe, resulting in its designation as a protected species under Annex II of the 1979 Bern Convention and the EC Habitats and Species Directive. The decline has been linked to a marked reduction in the extent of suitable calcareous and wet grassland habitats, habitats which have been lost through conversion of land to agriculture or urban areas, or reduced in quality due to inappropriate management. The UK is now one of the major strongholds for this butterfly in Europe, although much of the remaining habitat is small, isolated and highly fragmented. E. aurinia populations fluctuate greatly due to the combined effects of biotic (e.g. parasitoids) and abiotic (e.g. climate change) factors. We quantified the habitat associations of larval webs of E. aurinia on fragmented versus extensive (unfragmented) calcareous grassland habitat in southern England to test the hypothesis that habitat requirements of E. aurinia are more constrained within fragmented landscapes. Within both fragmented and unfragmented landscapes the quality and quantity of its main host plant in the UK, Succisa pratensis, was positively related to numbers of E. aurinia larval webs found. The sward height was also important at predicting the distribution of larval webs in both landscapes, although the heights were greater within sites in the unfragmented (&20 cm) compared to fragmented (&15 cm) landscape. We also found significant effects of elevation and the cover of bare ground on numbers of larval webs. Elevation was strongly correlated with the availability of host plant, whilst bare ground was only significant on sites within the fragmented landscape, showing a negative relationship with number of larval webs. Our results further emphasise the importance of not only maintaining the habitat quality of extant calcareous grassland sites for E. aurinia in the UK, but also increasing the size and connectivity of these sites to increase the chances and rate of (re)colonisation of unoccupied but suitable habitat. In addition, we show that the habitat requirements of E. aurinia on sites in a large unfragmented landscape may be less specific and thus require less extensive management than that required to create optimal conditions necessary at smaller, more isolated sites in fragmented landscapes

Relações entre a adubação nitrogenada e a qualidade de grãos e de sementes em aveia branca Relationships between nitrogen fertility and grain and seeds quality in oats

Com o objetivo de avaliar o efeito da adubação nitrogenada sobre atributos qualitativos dos grãos e das sementes em aveia branca, foi conduzido experimento envolvendo os cultivares, CTC 5, UFRGS 15, UFRGS 19 e UPF 18, e 0, 24, 48 e 73kg ha-1 de N como doses de adubação, em Argissolo Amarelo eutrófico típico, com 26,7g dm-3 de matéria orgânica. A qualidade industrial dos grãos foi avaliada através do peso do hectolitro de grãos (PH), do teor de proteína e do rendimento industrial; a qualidade das sementes foi estimada pelos testes de germinação e de envelhecimento acelerado. Independentemente do cultivar considerado, o incremento, nas doses de adubação nitrogenada reduz o peso do hectolitro, eleva a concentração de proteína nas cariopses e a produção de proteína e não afeta o rendimento industrial e a qualidade fisiológica das sementes.<br>With the objective of evaluating the effect of nitrogen (N) fertilization on grain and seeds quality parameters in oat, a field experiment was conducted with the cultivars CTC5, UFRGS 15, UFRGS 19 and UPF 18, and levels of N fertilization, 0, 24, 48 and 73kg ha-1 in a Typic Hapludalf soil, with 26.7g dm-3 of organic matter. The grain quality was evaluated trough the test weight, protein concentration and groat percentage; the seed quality was estimated by the germination test and accelerated aging test. Independently of the considered cultivar the increase on level of N, decrease the test weight results, increase the protein concentration in the caryopsis and the protein yield, and does not affect the caryopsis percentage and physiological quality seeds