Abstract
ContextUnderstanding how landscape patterns affect species diversity is of great importance in the fields of biogeography, landscape ecology and conservation planning, but despite the rapid advance in biodiversity analysis, investigations of spatial effects on biodiversity are still largely focused on species richness.ObjectivesWe wanted to know if and how species richness and species composition are differentially driven by the spatial measures dominating studies in landscape ecology and biogeography. As both measures require the same limited presence/absence information, it is important to choose an appropriate diversity measure, as differing results could have important consequences for interpreting ecological processes.MethodsWe recorded plant occurrences on 112 islands in the Baltic archipelago. Species richness and composition were calculated for each island, and the explanatory power of island area and habitat heterogeneity, distance to mainland and structural connectivity at three different landscape sizes were examined.ResultsA total of 354 different plant species were recorded. The influence of landscape variables differed depending on which diversity measure was used. Island area and structural connectivity determined plant species richness, while species composition revealed a more complex pattern, being influenced by island area, habitat heterogeneity and structural connectivity.ConclusionsAlthough both measures require the same basic input data, species composition can reveal more about the ecological processes affecting plant communities in fragmented landscapes than species richness alone. Therefore, we recommend that species community composition should be used as an additional standard measure of diversity for biogeography, landscape ecology and conservation planning.
Highlights
The relationship between biodiversity, local environment and landscape patterns has long occupied biologists and ecologists (Forster 1778; Watson 1835; Darwin 1859; Wallace 1880; Arrhenius 1921; MacArthur and Wilson 1967; Hanski 1999)
We recommend that species community composition should be used as an additional standard measure of diversity for biogeography, landscape ecology and conservation planning
Today this relationship marks the cornerstone of island biogeography and landscape ecology, the former being of renewed interest, 50 years after its conception (Patino et al 2017; Whittaker et al 2017)
Summary
The relationship between biodiversity, local environment and landscape patterns has long occupied biologists and ecologists (Forster 1778; Watson 1835; Darwin 1859; Wallace 1880; Arrhenius 1921; MacArthur and Wilson 1967; Hanski 1999). A wide range of studies within these disciplines have identified associations between biodiversity and habitat patch area (Arrhenius 1921; Lindgren and Cousins 2017), shape (Aggemyr and Cousins 2012), quality (De Sanctis et al 2010) and isolation (MacArthur and Wilson 1967; Lindgren and Cousins 2017), as well as habitat amount (Fahrig 2013), configuration and connectivity within a landscape (Haddad et al 2017), and historical properties of the focal habitat or landscape (Helm et al 2005) These examples show that the physical environment can shape diversity in different ways, but in the majority of cases, the measure of diversity used is species richness, i.e. the raw number of species counted in a particular patch. Measuring diversity using species richness has a long history in the species–area relationship (SAR), which is one of Landscape Ecol (2018) 33:2273–2284 the most fundamental and well-studied associations in ecology and biology, with overwhelming evidence that it exists (Arrhenius 1921; Kohn and Walsh 1994; Drakare et al 2006)
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