The Nearest Forest is Farther Away Than You Thought

Forested areas all across the country are shrinking rapidly -- especially in the West.

by Kastalia Medrano
Getty Images / Paula Bronstein

A new analysis of American deforestation offers a surprising stat: The average distance to the nearest forest increased by nearly 14 percent in the last decade. To put it another way, the total forest cover lost is comparable in size to the state of Maine.

The forest cover is also vanishing at a rate more than a full order of magnitude greater than we previously thought. A pair of researchers made the discovery by analyzing forest attrition — the complete removal of forest patches, including small ones — across the continental United States. The western part of the country especially was shown to have vastly accelerated rates of attrition. It’s noticeable even after normalizing for existing differences in forest cover, which means that part of the country is also significantly worse when it comes to how much farther the average person is getting from the nearest wooded area.

A study detailing the research was published Wednesday in the journal PLOS ONE.

“[Existing] efforts at cataloging focused more on large, intact forests,” co-author Giorgos Mountrakis tells Inverse. “But what we see is that we’re losing a lot of these isolated patches that are important for biodiversity. You can think of them as being like an oasis in the desert. They don’t tend to attract much attention.”

Forrest attrition is considerably greater in the western United States as compared to the east.

Yang S, Mountrakis G

Mountrakis has been analyzing this data along with co-author Sheng Yang for more than three years. Their theory was that climate change is accelerating the rate of attrition, but their focus for this study was on four primary drivers: commercial logging, agriculture, urbanization pressure, and forest fires. Now that they’ve completed a geographic analysis, the next step will be to figure out which drivers are affecting which areas. While the findings are difficult to predict before further research has been conducted, Mountrakis says we can probably expect to see a marked difference between the two coasts once again — likely more fires to the West and more logging to the East.

“We’re trying to link forest change to different socioeconomic factors,” Mountrakis says. “To try to see the importance that humans play into these transitions.”

A giant sequoia tree dwarfs the surrounding forest along the Trail of the 100 Giants in the Sequoia National Monument north of Kernville, California. 

Getty Images / David McNew

Even before the next round of data is gathered, government agencies could try to put this study to good use. Federal agencies would be the best fit since this research was conducted at the national level (again, just the continental United States though) — the National Forest Service, the United States Department of Agriculture, even maybe the Environmental Protection Agency could allow it to inform decision about what regions are appropriate for greater or reduced logging.

The study was funded by several entities including the National Urban and Community Forestry Advisory Council and the U.S. Forest Service, and Mountrakis believes that getting it into play with additional organizations — even state-level ones — could prove vital to mitigating the repercussions of attrition.

Forests are experiencing significant changes; studying geographic patterns in forests is critical in understanding the impact of forest dynamics to biodiversity, soil erosion, water chemistry, and climate. Few studies have examined forest geographic pattern changes other than fragmentation; however, other spatial processes of forest dynamics are of equal importance. Here, we study forest attrition, complete removal of forest patches, that can result in complete habitat loss, severe decline of population sizes and species richness, and shifts of local and regional environmental conditions. We aim to develop a simple yet insightful proximity-based spatial indicator capturing forest attrition that is independent of spatial scale and boundaries with worldwide application potential. Using this proximity indicator, we evaluate forest attrition across ecoregions, land ownership and urbanization stratifications across continental United States of America. Nationally, the total forest cover loss was approximately 90,400 km2, roughly the size of the state of Maine, constituting a decline of 2.96%. Examining the spatial arrangement of this change the average FAD was 3674m in 1992 and increased by 514m or 14.0% in 2001. Simulations of forest cover loss indicate only a 10m FAD increase suggesting that the observed FAD increase was more than an order of magnitude higher than expected. Furthermore, forest attrition is considerably higher in the western United States, in rural areas and in public lands. Our mathematical model (R2 = 0.93) supports estimation of attrition for a given forest cover. The FAD metric quantifies forest attrition across spatial scales and geographic boundaries and assesses unambiguously changes over time. The metric is applicable to any landscape and offers a new complementary insight on forest landscape patterns from local to global scales, improving future exploration of drivers and repercussions of forest cover changes and supporting more informative management of forest carbon, changing climate and species biodiversity.
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