title: Primary Succession on a Hawaiian Dryland Chronosequence.
abstract: We used measurements from airborne imaging spectroscopy and LiDAR to quantify the biophysical structure and composition of vegetation on a dryland substrate age gradient in Hawaii. Both vertical stature and species composition changed during primary succession, and reveal a progressive increase in vertical stature on younger substrates followed by a collapse on Pleistocene-aged flows. Tall-stature Metrosideros polymorpha woodlands dominated on the youngest substrates (hundreds of years), and were replaced by the tall-stature endemic tree species Myoporum sandwicense and Sophora chrysophylla on intermediate-aged flows (thousands of years). The oldest substrates (tens of thousands of years) were dominated by the short-stature native shrub Dodonaea viscosa and endemic grass Eragrostis atropioides. We excavated 18 macroscopic charcoal fragments from Pleistocene-aged substrates. Mean radiocarbon age was 2,002 years and ranged from < 200 to 7,730. Genus identities from four fragments indicate that Osteomeles spp. or M. polymorpha once occupied the Pleistocene-aged substrates, but neither of these species is found there today. These findings indicate the existence of fires before humans are known to have occupied the Hawaiian archipelago, and demonstrate that a collapse in vertical stature is prevalent on the oldest substrates. This work contributes to our understanding of prehistoric fires in shaping the trajectory of primary succession in Hawaiian drylands.
authors.affiliation: Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island, United States of America; Institute of Pacific Islands Forestry, United States Department of Agriculture Forest Service, Hilo, Hawaii, United States of America.
authors.forename: Kealohanuiopuna M
authors.initials: KM
authors.lastname: Kinney
authors.affiliation: Department of Global Ecology, Carnegie Institution for Science, Stanford, California, United States of America.
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Asner
authors.affiliation: Institute of Pacific Islands Forestry, United States Department of Agriculture Forest Service, Hilo, Hawaii, United States of America.
authors.forename: Susan
authors.initials: S
authors.lastname: Cordell
authors.affiliation: Department of Geography, University of California Santa Barbara, Santa Barbara, California, United States of America.
authors.forename: Oliver A
authors.initials: OA
authors.lastname: Chadwick
authors.affiliation: United States Department of Agriculture, Forest Service, Northern Research Station, Center for Accelerator Mass Spectrometry-Lawrence Livermore National Laboratory, Livermore, California, United States of America.
authors.forename: Katherine
authors.initials: K
authors.lastname: Heckman
authors.affiliation: Department of Botany, University of Wisconsin, Madison, Wisconsin, United States of America.
authors.forename: Sara
authors.initials: S
authors.lastname: Hotchkiss
authors.affiliation: Department of Botany, University of Wisconsin, Madison, Wisconsin, United States of America.
authors.forename: Marjeta
authors.initials: M
authors.lastname: Jeraj
authors.affiliation: Department of Global Ecology, Carnegie Institution for Science, Stanford, California, United States of America.
authors.forename: Ty
authors.initials: T
authors.lastname: Kennedy-Bowdoin
authors.affiliation: Department of Global Ecology, Carnegie Institution for Science, Stanford, California, United States of America.
authors.forename: David E
authors.initials: DE
authors.lastname: Knapp
authors.affiliation: Department of Biological Sciences, California Polytechnic University, Pomona, California, United States of America.
authors.forename: Erin J
authors.initials: EJ
authors.lastname: Questad
authors.affiliation: Department of Biological Sciences, Eastern Kentucky University, Richmond, Kentucky, United States of America.
authors.forename: Jarrod M
authors.initials: JM
authors.lastname: Thaxton
authors.affiliation: United States Geological Survey, Hawaii Volcano Observatory, Volcano, Hawaii, United States of America.
authors.forename: Frank
authors.initials: F
authors.lastname: Trusdell
authors.affiliation: Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island, United States of America.
authors.forename: James R
authors.initials: JR
authors.lastname: Kellner
mesh_terms: D017753:Ecosystem; D006254:Hawaii