Dominance and rarity in tree communities across the globe: Patterns, predictors and threats
Iris Hordijk, Lalasia Bialic‐Murphy, T. Bruce Lauber, Devin Routh, Lourens Poorter, Malin Rivers, Hans ter Steege, Jingjing Liang, Peter B. Reich, Sergio de‐Miguel, G.J. Nabuurs, Javier G. P. Gamarra, Han Y. H. Chen, Mo Zhou, Susan K. Wiser, Hans Pretzsch, Alain Paquette, Nicolas Picard, Bruno Hérault, Jean‐François Bastin, Giorgio Alberti, Meinrad Abegg, Yves C. Adou Yao, Angélica M. Almeyda Zambrano, Braulio Vílchez Alvarado, Esteban Álvarez‐Dávila, Patricia Álvarez-Loayza, Luciana F. Alves, Christian Ammer, Clara Antón‐Fernández, Alejandro Araujo‐Murakami, Luzmila Arroyo, Valerio Avitabile, Gerardo A. Aymard C., Timothy R. Baker, Olaf Bánki, Jorcely Barroso, Meredith L. Bastian, Luca Birigazzi, Philippe Birnbaum, Robert Bitariho, Pascal Boeckx, Frans Bongers, Olivier Bouriaud, Pedro H. S. Brancalion, Susanne Brandl, Roel Brienen, Eben N. Broadbent, Helge Bruelheide, Filippo Bussotti, Roberto Cazzolla Gatti, Ricardo G. César, Goran Češljar, Robin L. Chazdon, Chelsea Chisholm, Emil Cienciala, Connie J. Clark, David B. Clar, Gabriel Dalla Colletta, David A. Coomes, Fernando Cornejo Valverde, José Javier Corral‐Rivas, Philip M. Crim, Jonathan Cumming, Selvadurai Dayanandan, André Luís de Gasper, Mathieu Decuyper, Géraldine Derroire, Ben DeVries, Ilija Djordjević, Amaral Iêda, Aurélie Dourdain, Jiří Doležal, Nestor Laurier Engone Obiang, Brian J. Enquist, Teresa J. Eyre, Adandé Belarmain Fandohan, Tom M. Fayle, Leandro Valle Ferreira, Ted R. Feldpausch, Leena Finér, Markus Fischer, Christine Fletcher, Lorenzo Frizzera, Damiano Gianelle, Henry B. Glick, David J. Harris, Andrew L. Hector, Andreas Hemp, Geerten Hengeveld, John Herbohn, Annika Hillers, Eurídice N. Honorio Coronado, Cang Hui, Hyunkook Cho, Thomas Ibanez, Ilbin Jung, Nobuo Imai, Andrzej M. Jagodziński, Bogdan Jaroszewicz
Abstract
Abstract Aim Ecological and anthropogenic factors shift the abundances of dominant and rare tree species within local forest communities, thus affecting species composition and ecosystem functioning. To inform forest and conservation management it is important to understand the drivers of dominance and rarity in local tree communities. We answer the following research questions: (1) What are the patterns of dominance and rarity in tree communities? (2) Which ecological and anthropogenic factors predict these patterns? And (3) what is the extinction risk of locally dominant and rare tree species? Location Global. Time period 1990–2017. Major taxa studied Trees. Methods We used 1.2 million forest plots and quantified local tree dominance as the relative plot basal area of the single most dominant species and local rarity as the percentage of species that contribute together to the least 10% of plot basal area. We mapped global community dominance and rarity using machine learning models and evaluated the ecological and anthropogenic predictors with linear models. Extinction risk, for example threatened status, of geographically widespread dominant and rare species was evaluated. Results Community dominance and rarity show contrasting latitudinal trends, with boreal forests having high levels of dominance and tropical forests having high levels of rarity. Increasing annual precipitation reduces community dominance, probably because precipitation is related to an increase in tree density and richness. Additionally, stand age is positively related to community dominance, due to stem diameter increase of the most dominant species. Surprisingly, we find that locally dominant and rare species, which are geographically widespread in our data, have an equally high rate of elevated extinction due to declining populations through large‐scale land degradation. Main conclusions By linking patterns and predictors of community dominance and rarity to extinction risk, our results suggest that also widespread species should be considered in large‐scale management and conservation practices.