An old science is ﬁnding renewed relevance in the era of global climate change: phenology, the systematic study of seasonal events in the lives of plants and animals. Though the term itself was not coined until the mid-1800s, there are continuous records of the blooming of cherry trees in Kyoto, Japan, dating back to the eighth century. A millennium later, Gilbert White’s much-loved The Natural History of Selborne, published in 1789 and still in print, chronicled the comings and goings of willow wrens, chaffinches, hedge sparrows, woodlarks, and a host of other British birds, along with the appearances of insects and flowering plants.
Witness Tree, an appealing memoir by environmental journalist Lynda Mapes, sits squarely in this phenological tradition. It recounts a fellowship year spent at the Harvard Forest, a 3,500-acre ecological research preserve in central Massachusetts. For those with an abiding fondness for New England farmsteads and woodlots, Mapes offers up literary comfort food, as welcome as hot cocoa on a chilly day. She walks forest paths in sunshine, moonlight, rain, and snow; clambers over mossy stone walls; listens to the sounds of birds; and spies on tad-poles in a vernal pool. She gets per-sonal with the cows in a nearby pasture, and chats with local farmers and tradesmen about how the things were different in years gone by.
Most of all, Mapes watches and thinks about trees, for she is, by her own admission, “besotted with wood.” “Trees are time made visible,” she writes, and early in the year’s sojourn she adopts a century-old oak as the centerpiece for her rambles. It is a witness tree not only because it has seen a hundred years of seasons, but also because it bears witness to her jottings over the year. The author addresses her tree from all perspectives—taking a core sample to determine its age and growth history, lying on the ground at its base, climbing sixty feet into its crown with ropes and harnesses. And, since we live in the digital age, she even helps install a witness-tree webcam so that she and her readers can keep tabs on the venerable oak wherever they are and whenever they wish.
Just as change was a central concern of Gilbert White, so change is a focus here. Mapes writes of how the Harvard Forest differs from the primeval wilderness that existed for centuries before colonization, and how small farms and small industries came and went. And in conversations with the environmental researchers that work there, she discovers how climate change is altering it today. Leaves come out five days earlier on average than they did twenty-five years ago; first frost has moved back by almost two months. To walk with Mapes through these pages is not only to enjoy the charm of rural New England, but also to experience the global effects of our civilization—for better and for worse—on an intimate scale.