A new study by researchers at the University of California, Davis, published in the journal Nature Ecology and Evolution, finds that the human presence in the forests of the Pacific Northwest has had a profound effect on the nature of the environment there.
In the study, published May 19, the authors found that the number of plant species in the landscape that have grown in the last 150 years have decreased by an average of nearly 80 percent, while the number that have gone extinct has increased by an extra 30 percent.
That has meant that forests that once contained as many as 100,000 plant species are now less than 10,000.
The researchers found that these changes have occurred primarily in the lower elevations of the Cascade Mountains, where they found that, despite some improvements in recent decades, the number and diversity of plant life had declined by a third and 40 percent, respectively.
In contrast, the forests at the higher elevations in the area have continued to grow, increasing by almost 40 percent in the same time period.
While the authors note that their results do not prove that humans have caused the changes, they argue that their findings indicate that the effects are more widespread than previously believed.
“In some places the effects were not so pronounced, but in other places they were,” said lead author Sarah E. Wigley, a doctoral candidate in ecology at the UC Davis School of Forestry and Natural Resources.
“This suggests that we need to think about other causes that we might not have considered.”
The researchers say the study also shows that forests are not simply the natural habitat for plants, but also the habitat for humans.
The researchers note that they used data from the U.S. Geological Survey’s Integrated Land Cover System to analyze the area around the Cascade and Oregon coasts.
The system tracks forest cover, the size of the forest canopy and the extent to which humans and wildlife interact with the area.
The study also found that there are several types of plants that have been displaced from their natural habitat.
There are trees and shrubs that are gone from the landscape, and there are birds that are disappearing, as well.
The study found that some of these species are gone for good, but others are recovering.
The authors note, however, that the forest is not the only place where this process occurs.
It is not just the disappearance of certain species that are going to happen, but there is also the loss of other types of vegetation, such as grasses and shrub species, and also a significant increase in the amount of erosion.
“The forest canopy is not a fixed structure.
As more land is planted with timber, it is increasingly becoming an increasingly fragile structure,” Wig