Identities and distributions of the co-invading ectomycorrhizal fungal symbionts of exotic pines in the Hawaiian Islands

Nicole A Hynson,Kathleen K Treseder,Vincent S F T Merckx,Brian A Perry

doi:10.1007/s10530-013-0458-3

Abstract

Pine species have become invasive throughout the globe and threaten to replace native biota. The threat of pine invasion is particularly pressing in parts of the tropics where there are no native pines. The factors that govern pine invasion are not often well understood. However, key to pine survival is an obligate and mutualistic interaction with ectomycorrhizal fungi. Thus for pines to successfully invade new habitats compatible ectomycorrhizal fungi must already be present, or be co-introduced. The purpose of this study was to examine the community structure of non-native ectomycorrhizal fungi associated with pine invasions in the Hawaiian Islands. To accomplish this we executed a field and greenhouse study and used a molecular ecology approach to identify the fungi associating with invasive pines in Hawai‘i. We show that: (1) ectomycorrhizal fungal species richness in non-native pine plantations is far less than what is found in pine’s native range, (2) there was a significant decrease in average ectomycorrhizal fungal species richness as distance from pine plantations increased and, (3) Suillus species were the dominant fungi colonizing pines outside plantations. The keystone ectomycorrhizal fungal taxa responsible for pine establishment in Hawai‘i are within genera commonly associated with pine invasions throughout the globe. We surmise that these fungi share functional traits such as the ability for long-distance dispersal from plantations and host tree colonization via spore that lead to their success when introduced to new habitats.

Highlights

Coniferous tree species, especially pines, are the most abundant and widespread invasive trees (Richardson and Rejmanek 2004)
Treseder Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA 92697, USA. Accomplish this we executed a field and greenhouse study and used a molecular ecology approach to identify the fungi associating with invasive pines in Hawai‘i. We show that: (1) ectomycorrhizal fungal species richness in non-native pine plantations is far less than what is found in pine’s native range, (2) there was a significant decrease in average ectomycorrhizal fungal species richness as distance from pine plantations increased and, (3) Suillus species were the dominant fungi colonizing pines outside plantations
Other EM fungi in the genera or families Cadophora, Pseudotomentella, Cortinarius, Inocybe, Tuber, Laccaria, Pyronemataceae, Hyaloscyphaceae and another species of Suillus, S. brevipes, were site-specific and tended to be rare regardless of location (Fig. 1)

Summary

Introduction

Coniferous tree species, especially pines, are the most abundant and widespread invasive trees (Richardson and Rejmanek 2004). Pines have become invasive in over 40 countries where they threaten to replace the native biota (Richardson and Rejmanek 2004). Previous research has shown that pine invasion can produce dramatic effects on both above- and below-ground community structure, as well as alter abiotic ecosystem processes such as carbon sequestration and nutrient availability (Dickie et al 2011; Dodet and Collet 2012). The factors that govern successful pine invasions are not often well understood (Richardson and Rejmanek 2004; Nunez et al 2009; Dickie et al 2010; Nunez and Medley 2011). One important biotic interaction for pine establishment and growth is their association with root inhabiting symbiotic fungi

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Conclusion