Island biogeographic gradients and local environmental conditions differentially shape phylogenetic and functional diversity in Malesian tree assemblages
The islands of Malesia support exceptional tree diversity, yet the processes shaping the phylogenetic and functional diversity of local assemblages remain poorly understood. We analysed 191 forest plots across 12 islands spanning the bioregions of Sunda, Wallacea and Sahul, with 2,001 tree species represented in the dataset. We quantified the phylogenetic and functional diversity of each plot’s tree assemblage using standardised effect sizes of phylogenetic and functional richness (SESPD and SESFD). We tested how island area, isolation, local environmental conditions and geological disturbance were associated with plot-level SESPD and SESFD. Mean plot-level SESPD was significantly below zero in Sunda, indicating phylogenetic clustering, while mean SESFD indicated functional clustering across all three bioregions. Island area was negatively associated with both SESPD and SESFD, whereas distance to the mainland was positively associated with SESPD only. Earthquake proximity had opposing effects on the two dimensions, being associated with greater SESPD but lower SESFD. SESPD and SESFD were only weakly correlated among plots, and there was no correlation when assemblages were pooled within islands. Together, these results show that biogeographic processes at the island scale can leave distinct phylogenetic and functional signatures within local forest assemblages, and that species richness alone provides only a partial representation of how island tree diversity is structured.
Authors
- Clare Drinkell (ORCID: https://orcid.org/0009-0009-6887-7371)
- Francis Q. Brearley (ORCID: https://orcid.org/0000-0001-5053-5693)
- Deby Arifiani (ORCID: https://orcid.org/0000-0002-0381-8663)
- Endro Setiawan (ORCID: https://orcid.org/0000-0002-3655-4393)
- Eddy Nurtjahya (ORCID: https://orcid.org/0000-0003-4641-069X)
- Jon P. Sadler (ORCID: https://orcid.org/0000-0003-0443-4458)
- Teguh Triono (ORCID: https://orcid.org/0000-0003-2017-3841)
- Marie Briggs (ORCID: https://orcid.org/0000-0003-2988-0032)
- Endang Kintamani (ORCID: https://orcid.org/0000-0002-2991-4776)
- Laura V. S. Jennings (ORCID: https://orcid.org/0000-0001-6777-2281)
- Yessi Santika
- Renata Borosova (ORCID: https://orcid.org/0000-0002-3691-5005)
- Ferry J.W. Slik (ORCID: https://orcid.org/0000-0003-3988-7019)
- Osanna Chu (ORCID: https://orcid.org/0009-0000-3918-989X)
- I Putu Gede P. Damayanto (ORCID: https://orcid.org/0000-0001-8740-0696)
- Andes Hamuraby Rozak (ORCID: https://orcid.org/0000-0001-9641-5830)
- Fabian Brambach (ORCID: https://orcid.org/0000-0002-3203-2248)
- Alison Moore (ORCID: https://orcid.org/0000-0002-8286-0359)
- Anna Trias‐Blasi (ORCID: https://orcid.org/0000-0001-9745-3222)
- Grace Flanagan (ORCID: https://orcid.org/0009-0005-4060-0451)
- Julian Schrader (ORCID: https://orcid.org/0000-0002-8392-211X)
- Carmen Puglisi (ORCID: https://orcid.org/0000-0003-0304-1812)
- Liam A. Trethowan (ORCID: https://orcid.org/0000-0002-0326-9828)
- Douglas Sheil (ORCID: https://orcid.org/0000-0002-1166-6591)
- Cecilia Lee-Grant (ORCID: https://orcid.org/0000-0002-0830-0986)
- Meredith Bastian
- Muhammad Mansur
- Laura Graham
- Himmah Rustiami
- Thomas Matthews
- Tika Dewi Atika
- Gemma Bramley
- Asep Sadili
- Arief Hidayat
- Adriane Muelbert
- Ruth Clark
- Edi Mirmanto
- Asryaf Mansur
- Nithanel Benu
- Wahyudi Santoso
- Andrea Permana
- Tom Martin
- Rodrigo Cámara Leret
- Timothy Utteridge
- Zakaria Rahmad
- Deden Girmansyah
- Relawan Kuswandi
- Jimmy Wanma
- P. Wilkie
- Agustinus Murdjoko
- Alex Bradbury
- Charlie Heatubun
Institutions
- University of Birmingham (GB)
Publication Details
- Published
- 2026-10-27
- DOI
- https://doi.org/10.22541/authorea.15011116/v1
- Primary Topic
- Ecology and Vegetation Dynamics Studies
- Type
- preprint