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Differences in leaf and wood traits between alien and native species do not explain outperformance of invasive, alien species in a mesic forest on a subtropical oceanic island


Article title

Associations among species traits, distribution, and demographic performance after typhoon disturbance for 22 co-occurring woody species in a mesic forest on a subtropical oceanic island

Author (affiliation)

Yoshiko Iida (a), Shin Abe (b), Nobuyuki Tanaka (c), Tetsuto Abe (d)

(a) Center for Biodiversity, FFPRI, Tsukuba, Ibaraki, Japan.

(b) Department of Forest Vegetation, FFPRI, Tsukuba, Ibaraki, Japan.

(c) Tokyo University of Agriculture, Tokyo, Japan.

(d) Kyushu Research Center, FFPRI, Kumamoto, Japan.

Publication Journal

Oecologia, 191(4) :897–907, Springer, December 2019 DOI:10.1007/s00442-019-04531-9( External link )

Content introduction

Mesic forests on Hahajima Island, a subtropical oceanic island in the Ogasawara (Bonin) archipelago in the western Pacific Ocean (Photo 1), are characterized by high endemism, and are threatened by invasive, alien species such as Bischofia javanica (Phyllanthaceae) and Morus australis (Moraceae). We hypothesized that alien species would have traits associated with high resource acquisition and outperform native (indigenous or endemic) species on well-lit conditions after a typhoon disturbance. We measured leaf and wood traits which characterize species variations in resource acquisition strategies for 22 co-occurring species and examined associations between traits and performance.

Variations of leaf and wood traits were summarized along two axes associated with investment costs* in leaf and wood (Figure 1). Two alien species do not significantly differ from native species in any of the traits measured; however, they showed higher performance (higher recruitment and growth) than native species after a typhoon. Although species traits are expected to explain plant performance in several recent studies, our results show that differences in species traits do not explain outperformance of invasive species in a mesic forest on a subtropical oceanic island. Long-term monitoring that covers the whole life cycle of the species will be necessary to understand the underlying processes that allow successful invasion of island forests and guide future conservation efforts of endemic and indigenous species and their unique ecosystem.

* investment costs: cost to produce leaf and wood.


Figure1. Associations among the leaf 

Figure 1. Associations among the leaf and wood traits of the 22 species based on principal component analysis. Alien species (red) had similar traits compared with native (endemic and indigenous) species (black). Native species endemic to the Ogasawara islands and indigenous to Japan are shown as circles and triangles, respectively. Species abbreviations are listed as follows: Ardisi, Ardisia sieboldii; Biscja, Bischofia javanica; Callsu, Callicarpa subpubescens; Celtbo, Celtis boninensis; Drypin, Drypetes integerrima; Elaeph, Elaeocarpus photiniifolius; Ficubo, Ficus boninsimae; Ficuii, Ficus iidana; Hibigl, Hibiscus glaber; Machbo, Machilus boninensis; Machko, Machilus kobu; Meliaz, Melia azedarach; Meligr, Melicope grisea var. grisea; Moruau, Morus australis; Morubo, Morus boninensis; Ochrna, Ochrosia nakaiana; Pisoum, Pisonia umbellifera; Planob, Planchonella obovata var. obovata; Psycho, Psychotria homalosperma; Rhapin, Rhaphiolepis indica var. umbellata; Syzycl, Syzygium cleyerifolium; and Zantai, Zanthoxylum ailanthoides var. inerme.


Photo1. A mesic forest at Sekimon on Hahajima Island

Photo 1. A mesic forest at Sekimon on Hahajima Island in the Ogasawara islands