Fermentation is the action of life upon death; living organisms consume dead plant and animal matter, in the process freeing nutrients for the further sustenance of life.
—Sandor Ellix Katz, Wild Fermentation
When began to study wild plants I would often walk around the city aimlessly to see which species I’d find. I would gaze in bewilderment at the clusters of bledo (wild Amaranth) that grew amidst the sidewalk cracks, wondering why and how weeds could survive in the most hostile of environments: the urban, concrete jungle. What would happen if the city suspended its landscaping work and allowed bledo and other weeds to grow freely and take over buildings and empty lots? Would they heal this wound of a city and nurse it back into a healthy forest?
Specific weeds grow in a hostile (e.g. urban) environments because they are pioneer species in a process called ecological succession, which describes how the structure of species within a biological community (desert, rainforest, alpine, urban) changes over time. Ecological succession occurs through sequential progression, a process that favors species with evolved life histories to adapt to specific environments and lay the foundation for the next stage of ecological succession. The process seeks to construct an equilibrium as successive waves of species reinhabit a biological community, self-perpetuate, and continue to create ideal conditions for the propagation of new species. Sequential progression dictates that no stage in the process is random.
There are two types of ecological successions. Primary succession occurs in places either without soil or where the soil is incapable of sustaining life, such as rock exposed under glaciers, lava flows, and sand dunes. Secondary successions occur in established ecosystems after atmospheric or human disturbances which do not eliminate all forms of life and nutrients from the environment, such as hurricanes or urban development. Communities of species that begin to repopulate these disturbed ecosystems are called pioneer species. The most recognizable to humans are weeds and trees.
For the second workshop in the Rewilding Borikén series, farmer and micro-biotic collaborator Norysell Massanet demonstrated how ecological succession occurs on multiple levels, as she guided participants through the basics of fermentation and explained how bacterial successions also occur at a microscopic level inside your gut. She noted that changes in the microbial composition occur faster than in larger ecological successions—in some cases within hours or days. Her workshop highlighted that successions permeate the array of ecosystems, both visible to the naked eye and microscopic.
We gathered underneath two tarps on a drizzly November morning well into the Caribbean rainy season for the first half of Nory’s workshop entitled Preservas y Fermentos con Frutas y Hortalizas (“Preserve and Ferment with Fruits and Vegetables”). Nory shared her wealth of knowledge on the science and history of fermentation, and asked participants focus on observation and taking notes rather than hands-on participation. As such, she began the class with a theoretical component before moving on to the history and benefits of eating fermented foods like sauerkraut. She used sauerkraut as an example to emphasize how the proper microbial succession—the change of bacterial communities—during the fermentation process is responsible for the quality of the final product.
Microbial successions begin to occur the moment you start chopping cabbage to make sauerkraut. The presence of soils and acid-intolerant bacteria on the surface of the cabbage initiate the fermentation process, and as the succession progresses with the addition of salt and the creation of brine, new bacteria create a more acidic environment. This new microbial community makes way for more acid-tolerant bacteria like Lactobacillus spp., which complete the process of fermentation. The table below demonstrates the successions of bacteria in sauerkraut:
The parallels between ecological and microbial successions captivated my thoughts, and weeks after Nory’s class I was scouring locals forests trying to find examples of ecological successions that aligned with the succession in the table above. In the Luquillo Experimental Forest I discovered that the first plants to grow among forest debris were cochimba (Palicourea croceoides), yagrumos (Cecropia schreberiana) and camaseys (Miconia prasinia). Each plant species grows well in conditions of intense light, which occur in Borikén when powerful hurricanes uproot trees and leave holes in the forest canopies. Among their primary roles is to create shade and optimal soil conditions for secondary (non-pioneer) species like bejuco de garrote (Rourea surinamensis), a vine plant which thrives in the pre-hurricane shade of the forest. It could be said that the shade provided by pioneer species like cochimba, yagrumos, and camaseys is similar to the way that acid-tolerant bacteria create acidic conditions for Lactobacillus spp. to thrive. The initial colonizing species must thrive in order for the next wave of colonizing species to thrive.
Although ecological successions are often left to the wild, humans also help guide them where native species are at risk by the overgrowth of invasive species. Humans contribute to healthy ecological succession by eliminating invasive plant species and introducing less aggressive plant species that can thrive in specific environments without out-competing native species and leaving them without enough light, water or nutrients in the soil. Invasive species can be useful when reintroducing vegetation to disturbed environments, but if left completely unchecked they can prevent native species from re-establishing themselves. The role of humans in the guided ecological successions of disturbed environments is analogous to the human intervention in the guided microbial succession of sauerkraut.
Scientists are studying plant successions to better understand microbial successions. Because bacteria live, reproduce, and die at a faster rate than plants, microbial successions can be studied over a shorter amount of time and reflect patterns that would take years or decades to occur in ecological successions. There are limitations, however. The physiology of each organism (plants vs. bacteria) and their respective means of passing on genetic information points to a potential flaw in this theory. Bacteria can transfer genetic material simply by bumping into one another (as Nory demonstrated by bumping into tent legs), whereas plants pass on genetic information to future generations by sexual or asexual reproduction.
Flaws aside, the parallels between microbial and ecological successions suggest a common denominator: the inherent will of every life form to work collectively towards a future they may not live to experience. This begs the question: if humans neglect to care for the future of humankind, as well as all non-human life forms we depend on for survival, are we sewing the seeds of destruction in our own species? If reconnecting with fermentation can help bring us closer to the ecological successions that are occurring within our guts and all around us, then perhaps understanding interspecies collaborations can also help us see ourselves as part of a larger, interdependent, and future-oriented network of life and death.