Based on modern environmental practices, the apocalyptic desert world of Mad Max: Fury Road may be the future we are heading towards, but recent research has revealed that certain practices may prevent such a disaster and even encourage environmental growth.
Human-made shell middens may be improving life for western redcedar. “Hiker and western redcedar (Thuja plicata) on Elliott Creek Trail to Goat Lake” by Miguel Vieira is licensed under CC 2.0
In a recent study published in the journal, Nature Communications, Dr. Brian M. Starzomski and his fellow researchers of the University of Victoria discovered that resource use in the intertidal zone or the seashore by the Coastal First Nations, a Native American group, actually helped improve forest productivity over millennia. The team looked at how the soil composition at places where humans lived affected the growth of Western redcedar (Thuja plicata) in British Columbia, Canada.
The Coastal First Nations have lived in British Columbia for over 13,000 years. They mostly occupied areas near the shore to be close to many land resources such as edible plants and animals as well as marine resources such as fish and clams. Over time, human waste such as rocks, bones, plant material, charcoal, artefacts, and most significantly, shells, collected in shell middens at these sites. Because of a series of smallpox outbreaks in the 1800s, most of these sites have not been occupied as much in the last 150–250 years. However the presence of shells as well as the use of fire has changed the species composition of the forest and understory around these areas. In addition, the majority of the area studied has not been put into commercial use, so the environment has been well preserved.
It appears that the shells, charcoal, and other debris in the shell middens have significantly increased nutrient input, especially calcium. Decaying shells slowly release calcium in the form of calcium carbonate which remains in the soil and is important for the growth of western redcedar. In fact, calcium deficiencies have been proposed as an important reason for the death of the top leaves and branches of western redcedar. Calcium carbonate and charcoal left over from human fires also increase soil pH which can increase the accessibility of other important nutrients such as phosphorous32. In addition, the structure of shell middens can increase soil drainage. All of these factors help increase the growth of western redcedar and general forest productivity which was measured in terms of the height, width, and the area of the upper layer of the forest, and the greenness of the vegetation.
Dr. Starzomski and his team used airborne lidar, a detection system which uses lasers to measure distance, surveys of trees to detect past use of fire, modelling of trees and the terrain, and other ecological methods to study how long-term human occupation affected forest productivity at an area on the Central Coast of British Columbia. They compared measurements of forest productivity at habitation sites to those of forests along the entire coast in the study area. The team found that forest productivity was highest near habitation sites and decreased around 200 meters from the borders of the shell middens. For example, trees that were growing on habitation sites were much taller than those growing far away, and deeper shell middens had a greater impact on forest productivity. Clearly, humans living at these sites positively impacted the forest in this case.
To be sure, it has been previously shown that local patterns in forest productivity on the coast is primarily driven by insolation or solar energy received per square centimeter per minute, soil water retention, and nutrient accessability. However, the scientists’ data show that while these factors are influential, distance from human habitation sites is one of the most important factors for predicting forest productivity.
Dr. Andrew J. Trant, the lead researcher with the University of Waterloo, stated that “this work reinforces the local indigenous world views of connectednes…has important implications for helping us to think about what is ‘wild’ or ‘pristine’…and demonstrates just how persistent some eco-cultural legacies are.” With this knowledge, hopefully people will take into account their own practices of environmental sustainability and understand that although we have the power to make the earth into an apocalyptic wasteland, we also have the ability to nurture it and leave it even better than it was before.
Andrew J. Trant, Wiebe Nijland, Kira M. Hoffman, Darcy L. Mathews, Duncan McLaren, Trisalyn A. Nelson & Brian M. Starzomski, August 30, 2016. Intertidal resource use over millennia enhances forest productivity, Nature Communications, Volume 7 Article 12491. http://www.nature.com/articles/ncomms12491