Rarity patterns of woody plant species are associated with life form and diversification rates in Pacific islands forests.
AMERICAN JOURNAL OF BOTANY 2021;
108:946-957. [PMID:
34160827 PMCID:
PMC9328433 DOI:
10.1002/ajb2.1687]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 02/08/2021] [Indexed: 06/13/2023]
Abstract
PREMISE
Rarity is a complex and central concept in ecology and conservation biology. Yet, it is still poorly understood why some species are rare and others common. Here, we aimed to understand the drivers of species rarity patterns in woody plant communities.
METHODS
We analyzed the local abundance and landscape frequency of 121 woody plant species across 238 plots on American Samoa and Hawaiian islands. We first assessed whether taxonomy, life form (shrub, small tree, large tree), and dispersal syndrome (dispersed by animals or by other means) are associated with the rarity of species. We then analyzed phylogenetic patterns in plant rarity and tested whether rarity patterns are associated with species evolutionary distinctiveness and the number of species within genera and families.
RESULTS
Large trees were less abundant but more frequent than shrub species. Animal-dispersed species tended to be less abundant than species dispersed by other means, while species frequency was not associated with dispersal syndromes. Relative frequency in Hawai'i exhibited a more robust phylogenetic signal than did abundance. Both evolutionary distinctiveness and taxa species richness were significantly associated with the frequency of shrub species in Hawai'i.
CONCLUSIONS
Life form appears consistently associated with the rarity of species. High diversification rate is probably a key factor explaining landscape-scale rarity of native species on isolated archipelagos like Hawai'i. At the landscape scale, rarity appears to be inversely associated with evolutionary distinctiveness, but at the local scale, species abundance may be not associated with evolutionary distinctiveness.
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