Landscape Heterogeneity–Biodiversity Relationship: Effect of Range Size

<div><p>The importance of landscape heterogeneity to biodiversity may depend on the size of the geographic range of species, which in turn can reflect species traits (such as habitat generalization) and the effects of historical and contemporary land covers. We used nationwide bird survey data from Japan, where heterogeneous landscapes predominate, to test the hypothesis that wide-ranging species are positively associated with landscape heterogeneity in terms of species richness and abundance, whereas narrow-ranging species are positively associated with landscape homogeneity in the form of either open or forest habitats. We used simultaneous autoregressive models to explore the effects of climate, evapotranspiration, and landscape heterogeneity on the richness and abundance of breeding land-bird species. The richness of wide-ranging species and the total species richness were highest in heterogeneous landscapes, where many wide-ranging species showed the highest abundance. In contrast, the richness of narrow-ranging species was not highest in heterogeneous landscapes; most of those species were abundant in either open or forest landscapes. Moreover, in open landscapes, narrow-ranging species increased their species richness with decreasing temperature. These results indicate that heterogeneous landscapes are associated with rich bird diversity but that most narrow-ranging species prefer homogeneous landscapes—particularly open habitats in colder regions, where grasslands have historically predominated. There is a need to reassess the generality of the heterogeneity-biodiversity relationship, with attention to the characteristics of species assemblages determined by environments at large spatiotemporal scales.</p></div

Effect of interaction between annual mean temperature and proportion of forest cover on the richness of narrow-ranging species.

<p>For narrow-ranging species, the definition of 100 grids is used (see Appendix S2 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0093359#pone.0093359.s001" target="_blank">File S1</a>). Each point represents the relationship between the richness of narrow-ranging species and proportion of forest cover in each transect. Regression lines are based on the coefficients estimated with the simultaneous autoregressive model that incorporated the interaction term between these variables, at low temperature (upper 2.5% in the range of values in annual mean temperature, dotted line), mean temperature (50%, solid line), and high temperature (97.5%, broken line). Model performance is shown in Appendix S9 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0093359#pone.0093359.s001" target="_blank">File S1</a>.</p

Relationship between number of habitat types used by a species and range size.

<p>For range size, the number of 20-km-square grids occupied by the species (obtained from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0093359#pone.0093359-Ueta1" target="_blank">[27]</a>) is used for 107 out of 113 terrestrial bird species in Japan (except for six raptor species without range-size data). Values inside bars and error bars indicate sample size and standard error, respectively.</p

Locations of 313 study transects across the main four islands of Japan.

<p>Locations of 313 study transects across the main four islands of Japan.</p

Effect of interaction between annual mean temperature and proportion of forest cover on the richness of narrow-ranging species.

<p>For narrow-ranging species, the definition of 100 grids is used (see Appendix S2 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0093359#pone.0093359.s001" target="_blank">File S1</a>). Each point represents the relationship between the richness of narrow-ranging species and proportion of forest cover in each transect. Regression lines are based on the coefficients estimated with the simultaneous autoregressive model that incorporated the interaction term between these variables, at low temperature (upper 2.5% in the range of values in annual mean temperature, dotted line), mean temperature (50%, solid line), and high temperature (97.5%, broken line). Model performance is shown in Appendix S9 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0093359#pone.0093359.s001" target="_blank">File S1</a>.</p

Response of each species to proportion of forest cover at a landscape scale.

<p>(a, c) Relationships between abundance of each species and proportion of forest cover at a landscape scale and (b, d) pie charts showing the proportions of species with the four categories of response type (open-habitat species, mosaic-habitat species, forest species, and no response) among (a, b) 38 wide-ranging species, and (c, d) 19 narrow-ranging species. Regression lines for each species were calculated in the same way as those for species richness (see explanation in the caption to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0093359#pone-0093359-g002" target="_blank">Figure 2</a>). Criteria for categorization of each species according to the proportion of forest cover are given in the text.</p