PS 16-152 - CANCELLED - Effect of scale and environmental drivers on the variation of tree allometry across continental US

Monday, August 15, 2022

5:00 PM – 6:30 PM EDT

Located in: ESA Exhibit Hall

Presenting Author(s)

SM

Sergio Marconi, PhD

University of Florida, United States

Coauthor(s)

AS

Aditya Singh

University of Florida, United States
BW

Ben Weinstein

University of Florida, United States
EW

Ethan White, PhD

University of Florida, United States
AZ

Alina Zare

University of Florida, United States
SG

Sarah J. Graves, PhD

Graduate Program Manager
University of Florida, United States
MZ

Meilun Zhou

University of Florida, United States
RC

Ritesh Chowdhry

University of Florida, United States
IH

Ira Harmon

University of Florida, United States
SB

Stephanie Bohlman, PhD

University of Florida, United States

Background/Question/Methods

The relationship between tree height, stem diameter and crown size are key for determining ecosystem function, forest biomass and carbon storage. Although single allometric relationships are often used for species, functional groups or all trees, allometric relationships are affected by biological interactions, environmental heterogeneity and climate. How these driving factors vary across scale is not well understood, but important for determining forest structure and functioning. We quantified the relative importance of soil properties, climate, and forest density across scales on the parameters of dbh-height, dbh-crown size and height-crown area allometric relationships across the continental United States. We used a Bayesian mixed modeling approach to build scale-dependent relationships between allometric parameters and the environment for ~115 species leveraging data from the National Ecological Observatory Network and the US Forest Service. Using these models we ask (1) how do soil, climate and structure affect the parameters of different allometric relationships; (2) at which geographic scale does variation in environmental drivers and forest structure affect variation in allometric relationships across species and functional types; and (3) what is the potential effect of future changes in climate on the slope of allometric relationships for tree species across the continental USA.

Results/Conclusions

Our results showed that environmental drivers have an effect on dbh-height and dbh- crown size relationships (R² of 0.40 and 0.37), but not the height-crown size relationship (R² of 0.19). Soil carbon, cation exchange capacity and forest structure were the most important and consistent drivers affecting allometric relationships across species. Climate had the weakest effect, partly because the climate-allometric relationships had different magnitudes and signs depending on the species. The spatial scale with the greatest variation was the largest scale, followed by the meso scale. Local-scale variation showed weaker impact on the allometric relationships in general, but had the highest variance across species, making it important for a subset of US taxa. This suggests that studies focusing on large-scale changes in climate and soil properties may be useful for addressing future dynamics of tree allometry, forest growth and carbon storage. Our results also suggest that for species showing meaningful variation linked to temperature, climate change may have important effects on dbh-height-crown allocation. In conclusion, our results suggest that shifts in tree allometry are correlated with environmental drivers, with the implication that current and future climate patterns may lead to large scale shifts in tree structure.