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Plant Focus

Quercus macdougallii
A rare oak endemic to the Sierra Juárez in Oaxaca

Oaks in Podcasts: Acorn Dispersal and Breeding

Two podcasts posted online recently will be of interest to oak enthusiasts. Matt Candeias' excellent In Defense of Plants featured an interview with Dr. Michael Steele, author of the book Oak Seed Dispersal: A Study in Plant-Animal Interaction, published earlier this year. Many will be familiar with the role played by squirrels and jays in oak reproduction when they stash acorns where they may later be forgotten, but these activities are only the tip of the extremely complex iceberg of oak seed dispersal. Hear how oaks pump their acorns with various chemicals to ensure at least some survive long enough to germinate, learn about the role of predators like hawks and owls in ushering in the next generation of oak trees, and discover many more details of the intricate relationship between oaks and the animals that help scatter their acorns.

In Defense of Plants

Click on the image above or here to listen to the episode. See below for more information on Dr. Steele’s book.

The second podcast features an interview with Ken Asmus, the founder of Oikos Nursery. From 1982 till earlier this year, Oikos was an important source of rare fruit trees and other non-commercial perennial food plants, including oaks. Ken recently retired from the nursery business in order to better pursue his research into food-bearing plants for an era of climate change, as well as to contribute to large-scale public orchards and other biological reserves.

Ken talks of the origins of Oikos and his plant development approach, which stresses enriching plant populations rather than breeding specific, named cultivars. He explains the importance for his work of J. Russell Smith’s book Tree Crops: A permanent agriculture, the role of indigenous knowledge in understanding the range of acorn uses, and the contributions of grassroots plant breeders like Miguel Marquez in starting him on his journey towards developing easily edible acorns. Ken also discusses how others can take up his work, contributing to a decentralized process of perennial crop development.

Both Ken Asmus and Miguel Marquez have published articles in International Oaks, the IOS Journal; see links below:

Horticulture and Aesthetics of Hybrid Oaks - Ken Asmus (International Oaks No. 6, 1995)

Storing Viable Oak Pollen - Miguel B. Marquez (International Oaks No. 7, 1996)

Partisan Gardens

Click on the image above or here to listen to the interview on Partisan Gardens, a radio program and podcast broadcasting from Bloomington, Indiana, USA.

Oak Seed Dispersal

Oak Seed Dispersal: A Study in Plant-Animal Interactions

Michael A. Steele.

The definitive examination of oak forest evolutionary ecology.

Seed dispersal is a critical stage in the life cycle of most flowering plants. The process can have far-reaching effects on a species' biology, especially numerous aspects of its ecology and evolution. This is particularly the case for the oaks, in which the dispersal of the acorn is tied to numerous tree characteristics, as well as the behavior and ecology of the animals that feed on and move these seeds to their final destination. Forest structure, composition, and genetics often follow directly from the dispersal process—while also influencing it in turn.

In Oak Seed Dispersal, Michael A. Steele draws on three decades of field research across the globe (e.g., the United States, Mexico, Central America, Europe, and China) to describe the interactions between oaks and their seed consumers. Rodents, birds, and insects, he writes, collectively influence the survival, movement, and germination of acorns, as well as the establishment of seedlings, often indicating a coevolutionary bond between oaks and their seed consumers. This bond can only be understood by unraveling the complex interactions that occur in the context of factors such as partial seed consumption due to acorn chemistry, scatter hoarding, predation of the seed consumers by other organisms, and the limiting effects of masting on insect, rodent, and jay damage.

Offering new insights on how animal-mediated dispersal drives ecological and evolutionary processes in forest ecosystems, Oak Seed Dispersal also includes an overview of threatened oak forests across the globe and explains how a lack of acorn dispersal contributes to many important conservation challenges. Highly illustrated, the book includes photographs of key dispersal organisms and tactics, as well as a foreword by Stephen B. Vander Wall, a leading authority on food hoarding and animal-mediated seed dispersal, and beautiful artwork by Tad C. Theimer, also an accomplished ecologist.