Conifer trait study using multiple arboreta as common gardens

May 7, 2021

Plant physiology

Randy Long, PhD, Postdoctoral Scholar

We are excited to announce a new project using the conifer collection at the Holden Arboretum led by postdoctoral researcher Dr. Randy Long. He is using arboreta and botanic gardens across the United States to examine trait variation and plasticity in conifer species and how they are influenced by native range distributions. Randy and his collaborators believe that species will have the highest growth rates and success in gardens within their current ranges and that species currently found in a large variety of environments will show greater variation in traits as compared to species with narrow ranges. Botanic gardens and arboreta provide a unique opportunity to address these questions in long lived species since many of these organizations have the same species, sometimes clones of the same individuals, planted across large environmental gradients. Another benefit is that they have detailed records of the plantings and source material, as well as staff that are knowledgeable about the collections and local conditions.

The project is centered around the conifer collection at the Holden Arboretum, but Randy is collaborating with the National Arboretum (Washington DC), the Colorado Botanic Garden (Denver, CO), the Hoyt Arboretum (Portland, OR), the San Francisco Botanic Garden (CA), and the Huntington Botanic Gardens (Pasadena, CA). Randy has identified 30 species that are well represented across the gardens and will be measuring a set of traits related to plant fitness (aka functional traits), leaf and stem anatomy, and plant size at all the collaborating arboreta this summer. These measurements, combined with planting records from collections, will allow for the comparisons of growth rates, anatomy, and trait plasticity across the different garden environments. These measurements will help to provide insight into the mechanisms underlying the distribution of conifer species and responses to anthropogenic pressures.

A planting of *Thuja plicata* at the Holden Arboretum that includes individuals sourced from different states.

The conifer collection at the Holden Arboretum along Sperry Road

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