MAST YEAR

Reflections on a Year of Plenty

There’s a good bit of speculation that 2015 may be a mast year for many oaks. “Mast” is the fruit of forest trees, like acorns or nuts, but unlike traditional agricultural crops which have a (somewhat) predictable yield each year, forest trees have highly variable fruiting. Some years, oaks only produce a handful of acorns, but in mast years, the trees produce a ridiculous abundance of nuts. Over vast regions of the country, almost all of the oaks of a single species (and sometimes more than one species) prepare to produce the crop of a decade.

In Old Town, Alexandria, my walk from the metro has become as treacherous as the “black ice” of winter. The red oaks of King Street shower the sidewalks with small, perfectly round acorns like thousands of ball bearings. Ankles and knees: beware! When the wind blows, acorns pop on the hoods of parked cars like dried corn in a skillet.

Since medieval times, farmers have taken advantage
of mast years to feed livestock

In the forests, the impact of these boom and bust cycles ripples throughout the entire ecosystem. Bumper crops of acorns produce a feast for all kinds of birds and mammals. Throughout history, farmers have taken advantage of mast years to feed their livestock. In the wild, populations of Acorn Woodpeckers (Melanerpes formicivorus) on the West Coast of North America spike during mast years. And when one population spikes, it creates a domino effect through the whole system. Researchers at the Institute of Ecosystem Studies documented a surge in mice and deer during masting years. This in turn produces an uptick in ticks who feed on deer and mice. And because ticks produce Lyme disease, the incidences of it in human populations increases. Mice pillage ground-nesting birds such as some veery and warblers, so following mast years, these species decline. But increases in mice also result in a decrease of gypsy moth (Lymanthria dispar), a notable pest which defoliates a significant percentage of the eastern forest. Scientists call this chain of events a “trophic cascade.” The result can literally change the community composition of an entire ecosystem for years.

Why do trees mast? Some scientists speculate that trees deliberately develop an abundance to satiate seed eaters who might otherwise eat all the available acorns. The resulting leftovers increases the odds for germination of a next generation of oaks. Likewise, lean years help to keep populations of seed eaters so low that there are not enough to eat all the seeds during subsequent years. In a Machiavellian scheme, trees satiate animals one year only to starve them the next.

Masting may also be a way of balancing a tree’s limited resource. Producing a large seed crop takes a lot of energy. During mast years, trees shift energy into flower and seed production; the next year, seed production tends to be very low, but the trees grow more. There is an inevitable tradeoff between reproduction and growth.

My walks down acorn-littered sidewalks have me thinking about my own cycles of preparation and production. After several years of chaining myself to a desk at nights and early in the mornings, I have emerged with a book. The years spent in development with Claudia only heighten my relief and pleasure in having it out in the public. Writing a book is so different than a blog post; it lacks the immediate gratification of sharing an idea online with peers. But that long season of waiting has resulted in an extraordinary season of abundance.

Path through dune in Cape Cod near Newcomb Hollow Beach

For me, this has been a year of plenty. Not only in terms of my own work, but also in the relationships I’ve developed, the rich conversations I’ve had, and the wealth of knowledge shared with me. Travel has taken me to many wonderful places. In Dublin this past winter, I felt the palpable energy of a new generation of designers and gardeners eager to innovate and adapt. In Des Moines, I witnessed a small but mighty botanical garden creating genre-blurring plantings. In Portland, I toured some of the most idiosyncratic and expressive gardens I’ve ever seen; gardens that challenged me to rethink the way I approach place-making. I’ve driven across the dry savannas of north central Texas, traveled through the rolling fields and forests of the Brandywine Valle, wandered the boulder fields of the Alabama piedmont woodlands, and explored the craggy coastlines of the Massachusetts Cape. We are spoiled with so much beauty, so much life. I’ve sat in kitchen tables and broken bread with thoughtful, kind, and fascinating people—all united by a love of plants.

Meadow at Mt Cuba Center this November

This is my mast year. To all of you who have invited me, opened your gardens and kitchens, and shared with me pieces of your life, I thank you. You’ve stretched my mind, and you’ve stretched my heart. I am certainly not worthy, but I am so grateful.


Source: Koenig, Walter and Johannes Knops. “The Mystery of Masting Trees.” The American Scientist. Volume 93. July-August 2005