At The Bad Grass series: new science about old trees

The Bad Grass lecture series taking place at Salisbury’s White Hart Inn this winter is highlighting land care methods that increase biodiversity.

During the Thursday, Feb. 15, installment, speaker Christopher Roddick introduced upward of 60 attendees to conservation arboriculture, an approach to tree care as a form of ecosystem management.

Roddick’s career as the Brooklyn Botanic Garden’s head of arboriculture and lead foreman has sent him up into trees’ canopies and down into their root systems, teaching him the difference between vigor and vitality.

“Vigor is a plant’s ability to grow,” said Roddick. “If it’s growing really fast, we assume it is healthy. Actually, what health is is vitality, the amount of stored energy in the plant. The more energy a tree has in reserves, the more it can adjust and respond to stressors while increasing habitat for wildlife.”

He gave some practical tips for how to support tree vitality: increase soil health with compost or natural materials rather than synthetic fertilizers; allow leaves to fall and decompose in place; group trees together; avoid pesticides and fungicides; avoid clearing branches from older trees unless necessary for safety; if canopy reduction is necessary, prune from the tips; start trees from seed if possible or buy saplings that are not root bound in their container; keep young trees well watered; and prune trees for the first five to 15 years if they start off root-bound.

Roddick called trees holobiont (super-organisms) and described how almost every part contains fungi and other microorganisms essential to healthy function. The tree care techniques he recommends should therefore all be in service of maintaining those symbiotic relationships.

He noted that the trees we enjoy in our yards and landscapes are the same species that relied on being part of a system when they evolved in diverse and crowded forest environments. Their health hinges on our ability to provide them a system they can thrive in. Emerging forest ecology science is shedding light on how important relationships are to tree health- relationships with microbes, with the surrounding fauna, and with other trees in different life-cycle stages.

When you’re rooted in place, you’re an easy target, so trees have evolved to react, adapt and share resources among themselves. They economize by optimizing growth, getting rid of parts that are no longer needed, and compartmentalizing. Rather than healing from injury like humans do, trees grow new cells in new positions and shed or wall off dead cells.

Imagine a bristlecone pine that sprouted 5,000 years ago. While you can touch parts of the trunk that were growing vibrantly in the Bronze Age, the oldest part of the tree that is still actively growing is only 50 years old, and the needles are only a few years old. “The great duality of being a tree is that it is both young and old at the same time,” said Roddick

For Roddick, trees’ ecosystem services — like providing nectar to pollinators, habitat for wildlife, clean air, and carbon sequestration — are as important as their beauty and recreational value.

When asked the best way to increase biodiversity and ecosystem health on a property, he extolled the benefits of veteran trees that are embarking on the long process of dying, creating hollows for wildlife and nooks and crannies where fungi thrive. He also recommended planting keystone species like oak, maple, birch and willow that can host thousands of other species.

Of all the sunlight that hits the Earth, less than 1% gets caught by organisms that can use the energy. Roddick reminded the assembled gardeners that the vast majority of those are trees. He emphasized the importance of preserving trees into their later years as a means of increasing earth’s photosynthetic capacity.

The Bad Grass series is organized by local residents Page Dickey, Amy Cox Hall and Jeb Breece, whose goal is to “promote conversation and highlight the national thought leaders and practitioners we have in the region.”

The final lecture for this year’s series will take place at the White Hart Thursday, Feb. 29, at 5:30 p.m., and will be a panel discussion with Leslie Needham, Dee Salomon and Matt Sheehan on our human role in creating and maintaining natural landscapes. More information and tickets are available at www.silvaetpratum.com

Proceeds from the series’ ticket sales will be directed toward extending Falls Village’s pollinator-friendly roadside beds to the steps of the David M. Hunt Library.