B088-01
Functional Differences between Trees and Lianas in a Dry Tropical Forest: a Whole Plant Perspective
Monday, 14 December 2020: 17:30
Virtual
Jennifer S Powers, University of Minnesota Twin Cities, Department of Ecology, Evolution and Behavior, Minneapolis, MN, United States, Chris M Smith-Martin, Columbia University of New York, Ecology, Evolution and Environmental Biology, New York City, NY, United States, German Vargas, University of Minnesota, Department of Plant and Microbial Biology, Saint Paul, MN, United States; University of Minnesota Twin Cities, Department of Plant and Microbial Biology, St. Paul, MN, United States, Xiangtao Xu, Cornell University, Ecology and Evolutionary Biology, Ithaca, NY, United States and David Medvigy, University of Notre Dame, Biological Sciences, Notre Dame, IN, United States
Abstract:
Seasonally dry tropical forests account for large amounts of the total tropical forest cover, harbor unique biodiversity, and support vital ecosystem services. Plant functional diversity in dry forests is also high, and includes co-existing lianas (woody vines), evergreen trees and deciduous trees. This functional diversity is poorly represented in models, and data limitations contribute to this. Resolving these issues is important as droughts are changing dry forest composition and liana abundances are increasing over time, both of which can decrease forest carbon storage. We used extensive field surveys including whole plant harvests to investigate the differences in allocation, rooting depths, and hydraulic traits among lianas, evergreen trees and deciduous trees. We also explored the consequences of these differences for canopy phenology using the simulation model ED2.
We found that mature trees and lianas did not differ in patterns of biomass allocation to stems, although deciduous tree species allocated more biomass to coarse roots compared to lianas, which allocated more to leaves. Lianas and deciduous trees also differed in hydraulic traits: overall, lianas have larger (i.e. more negative) turgor loss point values and more drought-resistant xylem. Evergreen trees were intermediate, and did not differ from deciduous trees or lianas in allocation or hydraulic traits. By contrast, the coarse roots of evergreen trees were over twice as deep as lianas, which had maximum rooting depths of ~0.5 meters. Deciduous trees had distinct rooting depths, which were intermediate between lianas and evergreen trees. Simulations with ED2 confirmed that assuming that evergreen trees are more deeply rooted than co-occurring deciduous trees is necessary to correctly represent canopy phenology. Apparently, deeper roots is one mechanism that enables trees to maintain canopies of leaves year-round. Collectively, these studies highlight how plant strategies are integrated at the whole-plant level. Differences in rooting depths between evergreen and deciduous trees help explain their canopy processes. Future studies should focus on understanding our finding that lianas have both shallower rooting depths and more drought resistant leaves compared to trees.
