Winter. Despite clear, sunny skies, the temperatures are below freezing. Deep powder blankets the Fort Douglas Military Cemetery, dampening the bustle of cars and buildings a stone’s throw away. The cold has stripped the foliage from black locust trees planted along the perimeter of the fence, leaving pruned trunks standing guard over the hallowed, slumbering grounds. Later, as the sun sets, taking the last rays of day with it, the shadows of gravestones stretch like spectral tailings, gesturing to the past.
Planted in 1864, the black locust trees have survived over 150 winters. The first one was planted in the valley a few decades earlier by the Mormon pioneers of Utah. The trees were most likely chosen for a variety of favorable characteristics including drought tolerance and ability to grow in poor, sandy soils. Their hardiness is greatly attributed to the tree’s ability to fix nitrogen, through a symbiotic relationship with N-fixing bacteria which free up the element into a usable form. The Rhizobium bacteria are not just confined to a relationship with the black locust tree, but all other legumes; they are among the few microbes we understand more fully. Many more teem in the soil, responsible for the decomposition of organic material that frees up nutrients to be absorbed by other organisms. Typically, the myriad of microbes would cycle matter from the tree’s own decaying flower and leaf litter, but the introduction of human remains in the cemetery intervenes, interrupting the nutrient cycle with implications beyond a single tree species.
When a body is introduced into the ecosystem of the miniscule, its high-water content, small carbon-to-nitrogen ratio, and abundant nutrients create a “cadaver (or carcass) decomposition island,” or CDI. This “island” is a hotspot of increased microbial activity. Within the first year of burial, the body goes through several stages of decay where different microbial actors command the scene. Those that have evolved to grow quickly increase in number with the burst of nutrients early in decay. Then, as the processing of nutrients depletes the oxygen in the soil, different actors adapted to anaerobic metabolism multiply. As time goes on, actors once prolific fall into the process of decay themselves, increasing the diversity of the nutrient pool and drawing in participation of new actors. Different stages of decay offer different environmental agents, promoting entry and exit of microbial matter that increases biodiversity, landscape heterogeneity, and processes of cycling nutrients. All three are foundational for sustaining a healthy, functional ecosystem where life can thrive.
The cemetery is a place of paradox: a place of death, but also life. Billions of microbes thrive in the soil that carries the remains of those who’ve departed from this earthly realm. Their activity embodies and manifests life after death: our expired physical matter provides an immense rush of nutrients, propelling the energetic ebb and flow of microbial composition and function that translates death into life-giving forms. Once a part of a living soldier, a nitrogen atom may have traveled through summer, fall, and winter to embed in the heartwood of the black locust tree that grows above the soldier’s remains.
Spring. A warm breeze rustles the black locust branches into a swaying motion, pliant as a young dancer’s fluid limbs. Birds call out their songs. What once was a thick blanket of snow, now percolates deep within the soil. Beyond honking car horns and industrial hum, the groans of roots tapping deeper and branches stretching higher echo in the cemetery. In the wake of the receding cold, sluggish microbes quicken their metabolic processes. Amid the whirring and churning a low hum builds in volume. Life is waking.
Katherine Bui is a second-year master’s student completing her MS in Environmental Humanities at the University of Utah. She is interested in the intersection of the sciences and humanities, particularly as a way to understand and process how humans fit into, and shape, a changing landscape. b. 1996