“The proper selection of the kinds of domestic animals and cultivated plants or the type of agriculture best adapted to regional and local climatic and other conditions is of primary importance in the interest of progressive and prosperous agriculture…By this method it could have been predicted, long before it was determined by the slow and expensive process of experiments and practical experience, that certain crops could or could not be grown in Alaska.”
-A.D. Hopkins, “The Bioclimatic Law as Applied to Entomological Research and Farm Practise” The Scientific Monthly (1919)
As a 12-year-old boy in rural West Virginia circa 1869, Andrew Delmar Hopkins discovered that it was the smaller things in life that yielded the bigger reward. This discovery was made, by and large, with the aid of a hand lens, forceps, and a stoppered glass jar containing an ethanol-soaked cotton swab. He had happened upon insect collecting. In its own small way, this hobby would lead to his becoming one of the country’s preeminent entomologists during the late 19th century, and eventually to his being called the “father of North American forest entomology.” Not bad for a farmhand who had never enrolled in college.
Sourcing his finds from around his family’s farm in Jackson County, Hopkins captured and pinned these creatures on corkboard, obsessing over their minutiae in his meticulous anatomical drawings. At age 17 he took over the workings of the farm, putting bugs on the back burner. His attention to detail found a natural application in the rigors of planting, harvest and crop rotation, and his field savvy soon attracted the attention of the West Virginia Agricultural Experiment Station, a facility at which he would serve as vice-director for many years. His farming practices were informed by studied observation: noting where and when things grew best, and which factors—climate, topography, pest control—were most responsible for that growth. All the while Hopkins maintained his interest in insects, and it was through his careful study of bark beetles and their proliferation throughout the Appalachian pine forests that he began formulating a theory for climatic influence on species distribution. This would become known as Hopkins’ Bioclimatic Law, a concept today as familiar to the recreational gardener as it is to the farmer and the state forester.
Based on data collected both on the farm and in the field, Hopkins devised a calculation that took into account altitudinal, latitudinal and longitudinal changes in climate as they affect life history events: seed germination and flowering of plants; egg-laying and hatching of insects; migration and hibernation of birds and mammals. Somewhat simply put, Hopkins’ law states that, on the average—if local conditions such as slope and exposure are comparable—spring events will occur one day later and fall events one day earlier with each 100-foot increase in altitude, plus a day for every 15 minutes of latitude northward, plus 1.25 days for each degree of longitude westward. Thus spring would come to Kansas City (elevation 1,000; 39.11 degrees N latitude, -94.63 longitude) more than ten and half days earlier than it would to Omaha, Nebraska, at 1034 feet, 41.26 degrees N latitude, -95.93 longitude. Hopkins generally found this formula to hold true wherever he decided to look.
Observations like these led to the identification of altitudinal climate series, distinct bands of habitat zoned by differences in elevation. Farmers in his native West Virginia and elsewhere took notice: The siting and timing of crops became finer-tuned, resulting in higher yields. Plants and their attendant animals could now be classified according to their height preference. Physiographic regions were found to harbor vegetation evolved into marked altitudinal zones—some broad, some narrow, and some so closely abutting as to allow easy passage from one into the next.
In the Great Basin, that self-contained cupola of schizophrenic weather and ecological extremes, it is possible to witness the passing of the seasons simply by walking uphill at the right spot. Plants long since dried up on the plains are encountered on mountainsides in full flower, separated by mere miles and topographic contour lines. They are the showy late bloomers, enjoying a bright but brief emergence in the rarified air. Just as spring was delayed for these plants, so summer is foreshortened, and fall descends faster than it would on the plains. There are only so many days in the year. As one climbs, the greener seasons become increasingly attenuated, condensed into shorter spans.
Being both a high altitude, high latitude desert—much of the basin is above 4,000 feet, north of the 37th parallel—changes in height are typically accompanied by floral and faunal changes as well, dictated by differences in climate. In temperate, mountainous regions such as the Great Basin, where an elevation gain of two thousand feet can translate into ten additional inches of precipitation and a decrease in average temperature of 10-15 degrees, altitude change constitutes ecological change.
It is axiomatic that a plant will grow best according to its particular climatic requirements—it will flourish only if the requisite conditions of soil, moisture, temperature and sunlight exposure are met. Though it may germinate and flower and recruit in areas suboptimal or otherwise conditionally deficient, it will do so in a stunted or retarded fashion, compared to the ideal. Unlike the majority of animals, plants are generally not considered to be mobile organisms—their gametes may travel some distance by wind or water or exploitative transport, but once a seed has sprouted it is very much at the mercy of its surroundings. Thus it is also axiomatic that to ascertain prime conditions for a given species, one must observe its growth in various climes—native soils, alien soils—and systematically record all pertinent data: temperature, precipitation, latitude, longitude and so on. To produce optimal growth is to reproduce optimal growing conditions.
Hopkins would be heartened to learn that his law continues to influence spheres as diverse as home gardening, commercial and conservation silviculture, forest entomology, and agriculture in all its dizzying breadth and scope. It governs the distribution of life, he argued back in the 1920s; flouting such a law would seem foolhardy, indeed. But that was before globalization, before gene transplantation, before the acknowledgement of anthropogenic climate change. These days, anything goes.