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nitrogen cycle

Biosphere integrity

October 14, 2025 By EarthWise Leave a Comment

Human demand for resources continues to stress Earth's systems

Civilization has an enormous need to utilize the biosphere, that is, the regions of the surface, atmosphere, and bodies of water of the earth occupied by living organisms.  The biosphere supplies us with food, raw materials, and increasingly, climate protection.

A study by two European universities looked at functional biosphere integrity, which is essentially the plant world’s ability to regulate the state of the Earth system.  Functional biosphere integrity faces massive human interference from consumption of resources, biodiversity loss, and climate change.

Highly detailed analysis modeled water, carbon, and nitrogen flows at a fine resolution over the entire planet and provided a detailed inventory year-by-year since the year 1600.  Each area is then assigned a status based on its tolerance limits of ecosystem change.  An area can either be a Safe Operating Space, a Zone of Increasing Risk, or a High-Risk Zone.

As the Industrial Revolution took hold, the proportion of global land area where ecosystem changes went beyond the locally defined safe zone, increased.  The current analysis shows that 60% of global land areas are now out of the safe operating space and 38% are facing high risk.

Human demand for biomass continues to grow.  The Earth system is increasingly stressed as humanity channels it into its own uses through harvested crops, residues, and timber.  At the same time, photosynthesis activity is reduced by land cultivation and sealing off land with construction.  We are not good for the biosphere.

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60 percent of the world’s land area is in a precarious state

Photo, posted September 14, 2024, courtesy of Jan Helebrant via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Migratory bison in Yellowstone

September 30, 2025 By EarthWise Leave a Comment

How bison impact the environment inside Yellowstone National Park

Tens of millions of bison once migrated across the United States in enormous herds; tribal oral histories speak of it taking days for an entire herd to pass by.  These herds shaped the landscape and performed many ecosystem functions.  By the 1890s, the bison population had plummeted to fewer than 1,000 individuals.  Since then, dedicated conservation efforts – establishing protected areas and breeding programs – have led to the recovery of the species.  There are now about 400,000 bison, mostly existing in small, privately owned herds.

Yellowstone National Park is home to the last significant migratory bison herd.  Yellowstone was established as a national park in 1872 providing scientists with a unique opportunity to study how large grazing herbivores affect the landscape.  More than 5,000 bison live in the 3,500 square miles of the park. 

A 7-year study by researchers examined how bison change the soil and vegetation along their migratory route.  What looked like overgrazing turns out to allow plants to keep growing.  The bison graze and move on, increasing the density of microbes and nitrogen in the soil and significantly improving the nutrition for other herbivores.

The research validated what Indigenous peoples have known for many generations:  that bison helped shape this continent and having large numbers of them improve ecosystems for other animals as well.  Native American tribes would like to restore bison to their lands.  Whether some of the park fences might be removed to permit migration beyond official borders is under consideration.

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In Yellowstone, Migratory Bison Reawaken a Landscape

Photo, posted August 17, 2017, courtesy of Jacob W. Frank / NPS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

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