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Environmental gradients explain species richness and community composition of coastal breeding birds in the Baltic Sea.

Nord M, Forslund P - PLoS ONE (2015)

Bottom Line: The total number of species per square increased with increasing shoreline length, but increasing land area counteracted this effect in specialists.Differences in community composition between squares were associated with differences in land area and distance to open sea, both when considering all species pooled and each group separately.Thus, such areas should be prioritized for protection against human disturbance and used by management in reserve selection.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.

ABSTRACT
Scientifically-based systematic conservation planning for reserve design requires knowledge of species richness patterns and how these are related to environmental gradients. In this study, we explore a large inventory of coastal breeding birds, in total 48 species, sampled in 4646 1 km2 squares which covered a large archipelago in the Baltic Sea on the east coast of Sweden. We analysed how species richness (α diversity) and community composition (β diversity) of two groups of coastal breeding birds (specialists, i.e. obligate coastal breeders; generalists, i.e. facultative coastal breeders) were affected by distance to open sea, land area, shoreline length and archipelago width. The total number of species per square increased with increasing shoreline length, but increasing land area counteracted this effect in specialists. The number of specialist bird species per square increased with decreasing distance to open sea, while the opposite was true for the generalists. Differences in community composition between squares were associated with differences in land area and distance to open sea, both when considering all species pooled and each group separately. Fourteen species were nationally red-listed, and showed similar relationships to the environmental gradients as did all species, specialists and generalists. We suggest that availability of suitable breeding habitats, and probably also proximity to feeding areas, explain much of the observed spatial distributions of coastal birds in this study. Our findings have important implications for systematic conservation planning of coastal breeding birds. In particular, we provide information on where coastal breeding birds occur and which environments they seem to prefer. Small land areas with long shorelines are highly valuable both in general and for red-listed species. Thus, such areas should be prioritized for protection against human disturbance and used by management in reserve selection.

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Mean number of species (± 1 standard deviation) in relation to distance to open sea.Data are grouped with regard to distance to open sea (mean standardised, x-axis value ±0.25, respectively). Sample sizes are (from left to right) 1879, 931, 683, 531, 247, 160, 112, 51, 19, 23.
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pone.0118455.g004: Mean number of species (± 1 standard deviation) in relation to distance to open sea.Data are grouped with regard to distance to open sea (mean standardised, x-axis value ±0.25, respectively). Sample sizes are (from left to right) 1879, 931, 683, 531, 247, 160, 112, 51, 19, 23.

Mentions: The environmental variables (and interactions between them) had significant effects on the number of species in specialists (4 main effects and 4 interactions), generalists (3 main effects and 2 interactions) and all species combined (2 main effects and 2 interactions). Model outputs are given in S1 Model Output. The number of species per square increased with increasing shoreline length in both specialists (p<0.0001) and generalists (p<0.0001; Fig. 2). However, the effect of shoreline length was dependent on land area (interaction effect; Fig. 2); the number of specialist species increased strongly with increasing shoreline length when the land area was small, but the positive effect of shoreline decreased with increasing land area (p<0.0001; Fig. 3). Thus, the number of specialist species decreased with land area (negative main effect, p<0.0001; Fig. 2). In generalists, on the other hand, the shoreline effect on the number of species was generally positive (p<0.0001; Fig. 2) and only little influenced by land area (as revealed by a visual inspection of the interaction corresponding to Fig. 3, although the interaction effect was significant; p = 0.0003, Fig. 2). Distance to open sea had opposing effects on the two species groups; number of specialist species decreased with increasing distance to open sea (p<0.0001), whereas numbers of generalists increased (p = 0.004; Figs. 2 and 4). Archipelago width was negatively related to the number of generalist species (p = 0.001), but positively related to the number of specialists (p = 0.0001; Fig. 2), again showing a difference between the two groups. The different effects of distance to open sea, land area and archipelago width on specialists and generalists, respectively, indicate a turnover of species when moving along these gradients (i.e. from close to mainland to the open sea; see also the community composition analysis below).


Environmental gradients explain species richness and community composition of coastal breeding birds in the Baltic Sea.

Nord M, Forslund P - PLoS ONE (2015)

Mean number of species (± 1 standard deviation) in relation to distance to open sea.Data are grouped with regard to distance to open sea (mean standardised, x-axis value ±0.25, respectively). Sample sizes are (from left to right) 1879, 931, 683, 531, 247, 160, 112, 51, 19, 23.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4340961&req=5

pone.0118455.g004: Mean number of species (± 1 standard deviation) in relation to distance to open sea.Data are grouped with regard to distance to open sea (mean standardised, x-axis value ±0.25, respectively). Sample sizes are (from left to right) 1879, 931, 683, 531, 247, 160, 112, 51, 19, 23.
Mentions: The environmental variables (and interactions between them) had significant effects on the number of species in specialists (4 main effects and 4 interactions), generalists (3 main effects and 2 interactions) and all species combined (2 main effects and 2 interactions). Model outputs are given in S1 Model Output. The number of species per square increased with increasing shoreline length in both specialists (p<0.0001) and generalists (p<0.0001; Fig. 2). However, the effect of shoreline length was dependent on land area (interaction effect; Fig. 2); the number of specialist species increased strongly with increasing shoreline length when the land area was small, but the positive effect of shoreline decreased with increasing land area (p<0.0001; Fig. 3). Thus, the number of specialist species decreased with land area (negative main effect, p<0.0001; Fig. 2). In generalists, on the other hand, the shoreline effect on the number of species was generally positive (p<0.0001; Fig. 2) and only little influenced by land area (as revealed by a visual inspection of the interaction corresponding to Fig. 3, although the interaction effect was significant; p = 0.0003, Fig. 2). Distance to open sea had opposing effects on the two species groups; number of specialist species decreased with increasing distance to open sea (p<0.0001), whereas numbers of generalists increased (p = 0.004; Figs. 2 and 4). Archipelago width was negatively related to the number of generalist species (p = 0.001), but positively related to the number of specialists (p = 0.0001; Fig. 2), again showing a difference between the two groups. The different effects of distance to open sea, land area and archipelago width on specialists and generalists, respectively, indicate a turnover of species when moving along these gradients (i.e. from close to mainland to the open sea; see also the community composition analysis below).

Bottom Line: The total number of species per square increased with increasing shoreline length, but increasing land area counteracted this effect in specialists.Differences in community composition between squares were associated with differences in land area and distance to open sea, both when considering all species pooled and each group separately.Thus, such areas should be prioritized for protection against human disturbance and used by management in reserve selection.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.

ABSTRACT
Scientifically-based systematic conservation planning for reserve design requires knowledge of species richness patterns and how these are related to environmental gradients. In this study, we explore a large inventory of coastal breeding birds, in total 48 species, sampled in 4646 1 km2 squares which covered a large archipelago in the Baltic Sea on the east coast of Sweden. We analysed how species richness (α diversity) and community composition (β diversity) of two groups of coastal breeding birds (specialists, i.e. obligate coastal breeders; generalists, i.e. facultative coastal breeders) were affected by distance to open sea, land area, shoreline length and archipelago width. The total number of species per square increased with increasing shoreline length, but increasing land area counteracted this effect in specialists. The number of specialist bird species per square increased with decreasing distance to open sea, while the opposite was true for the generalists. Differences in community composition between squares were associated with differences in land area and distance to open sea, both when considering all species pooled and each group separately. Fourteen species were nationally red-listed, and showed similar relationships to the environmental gradients as did all species, specialists and generalists. We suggest that availability of suitable breeding habitats, and probably also proximity to feeding areas, explain much of the observed spatial distributions of coastal birds in this study. Our findings have important implications for systematic conservation planning of coastal breeding birds. In particular, we provide information on where coastal breeding birds occur and which environments they seem to prefer. Small land areas with long shorelines are highly valuable both in general and for red-listed species. Thus, such areas should be prioritized for protection against human disturbance and used by management in reserve selection.

Show MeSH