title: Soil resources and topography shape local tree community structure in tropical forests.
abstract: Both habitat filtering and dispersal limitation influence the compositional structure of forest communities, but previous studies examining the relative contributions of these processes with variation partitioning have primarily used topography to represent the influence of the environment. Here, we bring together data on both topography and soil resource variation within eight large (24-50 ha) tropical forest plots, and use variation partitioning to decompose community compositional variation into fractions explained by spatial, soil resource and topographic variables. Both soil resources and topography account for significant and approximately equal variation in tree community composition (9-34% and 5-29%, respectively), and all environmental variables together explain 13-39% of compositional variation within a plot. A large fraction of variation (19-37%) was spatially structured, yet unexplained by the environment, suggesting an important role for dispersal processes and unmeasured environmental variables. For the majority of sites, adding soil resource variables to topography nearly doubled the inferred role of habitat filtering, accounting for variation in compositional structure that would previously have been attributable to dispersal. Our results, illustrated using a new graphical depiction of community structure within these plots, demonstrate the importance of small-scale environmental variation in shaping local community structure in diverse tropical forests around the globe.
authors.affiliation: Program in Ecology, Evolution, and Conservation Biology, University of Illinois, 505 S. Goodwin Ave, Urbana, IL 61801, USA. baldeck2@life.illinois.edu
authors.forename: Claire A
authors.initials: CA
authors.lastname: Baldeck
authors.forename: Kyle E
authors.initials: KE
authors.lastname: Harms
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Yavitt
authors.forename: Robert
authors.initials: R
authors.lastname: John
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Turner
authors.forename: Renato
authors.initials: R
authors.lastname: Valencia
authors.forename: Hugo
authors.initials: H
authors.lastname: Navarrete
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Davies
authors.forename: George B
authors.initials: GB
authors.lastname: Chuyong
authors.forename: David
authors.initials: D
authors.lastname: Kenfack
authors.forename: Duncan W
authors.initials: DW
authors.lastname: Thomas
authors.forename: Sumedha
authors.initials: S
authors.lastname: Madawala
authors.forename: Nimal
authors.initials: N
authors.lastname: Gunatilleke
authors.forename: Savitri
authors.initials: S
authors.lastname: Gunatilleke
authors.forename: Sarayudh
authors.initials: S
authors.lastname: Bunyavejchewin
authors.forename: Somboon
authors.initials: S
authors.lastname: Kiratiprayoon
authors.forename: Adzmi
authors.initials: A
authors.lastname: Yaacob
authors.forename: Mohd N Nur
authors.initials: MN
authors.lastname: Supardi
authors.forename: James W
authors.initials: JW
authors.lastname: Dalling
mesh_terms: D044822:Biodiversity; D017753:Ecosystem; D004777:Environment; D011157:Population Dynamics; D012987:Soil / Q000737:chemistry*; D014197:Trees / Q000502:physiology*; D014329:Tropical Climate
chemical_list: D012987:Soil