Ectomycorrhizal associations in the tropics – biogeography, diversity patterns and ecosystem roles

<jats:sec><jats:label /><jats:p> <jats:table-wrap position="anchor"> <jats:table frame="hsides"> <jats:col /> <jats:col /> <jats:col /> <jats:thead> <jats:tr> <jats:th>Contents</jats:th> </jats:tr> </jats:thead> <jats:tbody> <jats:tr> <jats:td /> <jats:td><jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#nph15151-sec-1002">Summary</jats:ext-link></jats:td> <jats:td>1076</jats:td> </jats:tr> <jats:tr> <jats:td>I.</jats:td> <jats:td><jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#nph15151-sec-0002">Introduction</jats:ext-link></jats:td> <jats:td>1076</jats:td> </jats:tr> <jats:tr> <jats:td>II.</jats:td> <jats:td><jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#nph15151-sec-0003">Historical overview</jats:ext-link></jats:td> <jats:td>1077</jats:td> </jats:tr> <jats:tr> <jats:td>III.</jats:td> <jats:td><jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#nph15151-sec-0004">Identities and distributions of tropical ectomycorrhizal plants</jats:ext-link></jats:td> <jats:td>1077</jats:td> </jats:tr> <jats:tr> <jats:td>IV.</jats:td> <jats:td><jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#nph15151-sec-0005">Dominance of tropical forests by ECM trees</jats:ext-link></jats:td> <jats:td>1078</jats:td> </jats:tr> <jats:tr> <jats:td>V.</jats:td> <jats:td><jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#nph15151-sec-0006">Biogeography of tropical ECM fungi</jats:ext-link></jats:td> <jats:td>1081</jats:td> </jats:tr> <jats:tr> <jats:td>VI.</jats:td> <jats:td><jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#nph15151-sec-0007">Beta diversity patterns in tropical ECM fungal communities</jats:ext-link></jats:td> <jats:td>1082</jats:td> </jats:tr> <jats:tr> <jats:td>VII.</jats:td> <jats:td><jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#nph15151-sec-0013">Conclusions and future research</jats:ext-link></jats:td> <jats:td>1086</jats:td> </jats:tr> <jats:tr> <jats:td /> <jats:td><jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#nph15151-sec-0014">Acknowledgements</jats:ext-link></jats:td> <jats:td>1087</jats:td> </jats:tr> <jats:tr> <jats:td /> <jats:td><jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#nph15151-bibl-0001">References</jats:ext-link></jats:td> <jats:td>1087</jats:td> </jats:tr> </jats:tbody> </jats:table> </jats:table-wrap> </jats:p></jats:sec><jats:sec><jats:title>Summary</jats:title><jats:p>Ectomycorrhizal (<jats:styled-content style="fixed-case">ECM</jats:styled-content>) associations were historically considered rare or absent from tropical ecosystems. Although most tropical forests are dominated by arbuscular mycorrhizal (<jats:styled-content style="fixed-case">AM</jats:styled-content>) trees, <jats:styled-content style="fixed-case">ECM</jats:styled-content> associations are widespread and found in all tropical regions. Here, we highlight emerging patterns of <jats:styled-content style="fixed-case">ECM</jats:styled-content> biogeography, diversity and ecosystem functions, identify knowledge gaps, and offer direction for future research. At the continental and regional scales, tropical <jats:styled-content style="fixed-case">ECM</jats:styled-content> systems are highly diverse and vary widely in <jats:styled-content style="fixed-case">ECM</jats:styled-content> plant and fungal abundance, diversity, composition and phylogenetic affinities. We found strong regional differences among the dominant host plant families, suggesting that biogeographical factors strongly influence tropical <jats:styled-content style="fixed-case">ECM</jats:styled-content> symbioses. Both <jats:styled-content style="fixed-case">ECM</jats:styled-content> plants and fungi also exhibit strong turnover along altitudinal and soil fertility gradients, suggesting niche differentiation among taxa. Ectomycorrhizal fungi are often more abundant and diverse in sites with nutrient‐poor soils, suggesting that <jats:styled-content style="fixed-case">ECM</jats:styled-content> associations can optimize plant nutrition and may contribute to the maintenance of tropical monodominant forests. More research is needed to elucidate the diversity patterns of <jats:styled-content style="fixed-case">ECM</jats:styled-content> fungi and plants in the tropics and to clarify the role of this symbiosis in nutrient and carbon cycling.</jats:p></jats:sec>