Ghost forest
Ghost forests are areas of dead trees in former forests, typically in coastal regions where rising sea levels or tectonic shifts have altered the height of a land mass. Forests located near the coast or estuaries may also be at risk of dying through saltwater poisoning, if invading seawater reduces the amount of freshwater that deciduous trees receive for sustenance. Phantom forests refer to a different issue with forests.
Formations
Sea level changes
When there is a change in sea level, coastal regions may become inundated with sea water. This can alter coastal areas and kill large areas of trees, leaving behind what is called a "ghost forest." This type of ghost forest may develop in a variety of environments and in many different places. In the southern US, coastal marshes are expanding into dry wooded areas, killing trees and leaving behind areas of dead trees called snags.Regions of the US at or below sea level are more susceptible to tides. Coastal features affected by changing sea levels are indirectly affected by climate change. With global sea-level rise, the coastlines in the southern US are being altered and leaving behind salt marshes filled with dead and dying trees in some areas.
Tectonic activity
Ghost forests can also result from tectonic activity. In the Pacific Northwest, there is a large, active subduction zone called the Cascadia Subduction Zone. Here, there is a convergent plate boundary where the Gorda Plate, the Juan de Fuca Plate, and the Explorer Plate are being subducted underneath the North American plate. As these plates attempt to slide past one another, they often become stuck. For several hundred years, the plates will be locked in place and the tension builds. As a result of this tension, there is an orogenic uplift. This is where the tension building between two converging plates gets translated into the vertical uplift of the mountains on the coast. Orogenic uplift is usually associated with earthquakes and mountain buildings. But then, every 500+ years, there is a large earthquake in the Cascadia Subduction Zone and all that built-up tension is released. The release of this tension results in what is called subsidence. And with subsidence the once elevated coastline drops down several meters to below sea level. Here, sea level has not changed, but the coastline has been deformed, making it susceptible to tides. Areas of the coastline can be inundated with sea water, creating marshes and leaving behind ghost forests.The Cascadia event was documented by geologist Brian Atwater in his book, The Orphan Tsunami. Gathering evidence from both the trees and the ground, he determined that the earthquake and tsunami had occurred sometime between 1680 and 1720, but he could not pinpoint the exact date. Japanese scientists, who had extensive records of tsunamis dating back to 684 AD, read the report, and told Atwater that they knew the date and even the precise time: January 26, 1700 at 9:00 p.m. Several hours after the earthquake, tsunami waves had crossed the ocean and wiped out a fishing village. The Japanese were baffled because there was no earthquake anywhere near Japan to account for the tsunami. The ghost forest in Washington thus provided the evidence for its origin.