Mycorrhizal feedbacks influence global forest structure and diversity
Camille S. Delavaux, Joseph A. LaManna, Jonathan A. Myers, Richard P. Phillips, Salomón Aguilar, David Allen, Alfonso Alonso, Kristina J. Anderson‐Teixeira, Matthew E. Baker, Jennifer L. Baltzer, Pulchérie Bissiengou, Mariana Bonfim, Norman A. Bourg, Warren Y. Brockelman, David F. R. P. Burslem, Li‐Wan Chang, Chen Yang, Jyh‐Min Chiang, Chengjin Chu, Keith Clay, Susan Cordell, Mary R. Cortese, J. den Ouden, Christopher W. Dick, Sisira Ediriweera, Erle C. Ellis, Anna T. C. Feistner, Amy L. Freestone, Thomas W. Giambelluca, Christian P. Giardina, Gregory S. Gilbert, Fangliang He, Jan Holík, Robert W. Howe, Walter Huaraca Huasco, Stephen P. Hubbell, Faith Inman, Patrick A. Jansen, Daniel J. Johnson, Kamil Král, Andrew J. Larson, Creighton M. Litton, James A. Lutz, Yadvinder Malhi, Krista L. McGuire, Sean M. McMahon, William J. McShea, Hervé Memiaghe, Anuttara Nathalang, Natalia Norden, Vojtêch Novotný, Michael J. O’Brien, David A. Orwig, Rebecca Ostertag, Geoffrey G. Parker, Rolando Pérez, Glen Reynolds, Sabrina E. Russo, Lawren Sack, Pavel Šamonil, I‐Fang Sun, Mark E. Swanson, Jill Thompson, María Uriarte, John Vandermeer, Xihua Wang, Ian M. Ware, George D. Weiblen, Amy Wolf, Shuhui Wu, Jess K. Zimmerman, T. Bruce Lauber, Daniel S. Maynard, Thomas W. Crowther, Colin Averill
Abstract
One mechanism proposed to explain high species diversity in tropical systems is strong negative conspecific density dependence (CDD), which reduces recruitment of juveniles in proximity to conspecific adult plants. Although evidence shows that plant-specific soil pathogens can drive negative CDD, trees also form key mutualisms with mycorrhizal fungi, which may counteract these effects. Across 43 large-scale forest plots worldwide, we tested whether ectomycorrhizal tree species exhibit weaker negative CDD than arbuscular mycorrhizal tree species. We further tested for conmycorrhizal density dependence (CMDD) to test for benefit from shared mutualists. We found that the strength of CDD varies systematically with mycorrhizal type, with ectomycorrhizal tree species exhibiting higher sapling densities with increasing adult densities than arbuscular mycorrhizal tree species. Moreover, we found evidence of positive CMDD for tree species of both mycorrhizal types. Collectively, these findings indicate that mycorrhizal interactions likely play a foundational role in global forest diversity patterns and structure.