Author: Allyson Ropp, Historic Preservation Archaeology Specialist
Let's explore the jungles of Central America, where ancient civilizations like the Maya and the Aztecs once thrived. These societies built impressive networks of cities and temples in the jungles. However, they disappeared due to reasons such as Spanish colonization and environmental problems, causing the jungles to reclaim these cities. Nature took over, with vines and trees climbing the walls, and the rainforest canopy hiding the buildings. Microbes like fungi and lichen obscure the engravings and adornments throughout the cities. Animals and birds made these cities their home, just like people did in the past, filling the halls and roaming the streets that were once active with trade and festivities.
This takeover by plants, animals, and microbes caused the structures to deteriorate over time. Animals damage the buildings by knocking over loose rocks, while roots of plants push up stones that become eroded by microbes. These biological processes drive the creation of archaeological sites.
The impact of biological processes on a site depends on the local climate and changes happening worldwide. Each organism will respond differently to temperature changes, extreme weather events, and shifts in water quality. The local habitat also determines which organisms will be present in a particular area. For instance, the equator's heat makes it difficult for larger animals like moose and reindeer to survive there. Larger animals thrive in colder climates, while smaller animals dominate warmer climates.
Similarly, plants are uniquely adapted to their surroundings. For example, marsh grasses develop special root systems to handle water with high salt concentrations. They even form beneficial relationships with crabs, who help oxygen get to the plant roots with their burrows in exchange for protection from the crabs’ predators. These adaptations take hundreds of years to develop. However, with rapid climate changes today, organisms all over the world face pressures to adapt to rising temperatures, changes in precipitation, and habitat loss. The changing of organisms’ habitable ranges and loss of species, in turn, affect the surrounding environment, including archaeological sites.
In North Carolina, the state's diverse geography leads to varied environmental changes. The coastal plain, piedmont, and mountains each support unique species that are adapted to their specific conditions. Coastal Plain species are adapted to sandy soils, shallow water tables, and saltwater flooding. Organisms in the Piedmont can survive in wetlands in the east and low foothills in the west. The Mountains host species that live in cooler temperatures and low-lying cove forests. With changes in temperature and precipitation, habitation ranges are expanding, some species may be lost, and growing seasons are lengthening.
The expansion and changing of organisms across the state have implications for archaeological sites both on land and underwater. Just as seen in Central America, the Adam Spach House in Davidson County, constructed in the mid-1700s, was left abandoned to be reclaimed by nature. Moss and roots have taken over the structure, causing it to decay. Coastal and marine environments face similar challenges, where various organisms like marsh grasses, crabs, oysters, fish, and microorganisms latch onto structures like the wharves at Brunswick Town in Brunswick County. While some of these organisms can contribute to the preservation of elements by burying them further, they often do more harm than good.
The relationship between biology and archaeological sites is complex, but understanding these processes is essential, especially with the significant changes we are witnessing today. By studying how biology affects archaeological sites, we can learn how to better preserve and protect our history and heritage.
Main image: Marsh grasses growing on top of wharf structure at Brunswick Town/Fort Anderson State Historic Site along the Cape Fear River (Image by NCOSA, 2021)
This material was produced with assistance from the Emergency Supplemental Historic Preservation Fund, administered by the National Park Service, Department of the Interior. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Department of the Interior.
Wachovia Historical Society
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2020 Adjusting the lens of invasion biology to focus on the impacts of climate-driven range shifts. Nature Climate Change, Vol 10, pg 398–405.