Plants bounce light to forest floor

Recent research has shown that plants help themselves grow by releasing volatile organic compounds. These chemicals form a mist of aerosols above the vegetation that blocks some of the direct light but enhances diffuse light. This boosts the solar radiation reaching the forest understory and increases growth.

Alexandru Rap from the University of Leeds, UK, and colleagues assessed the impact of plant volatiles on primary productivity by using atmospheric and vegetation models along with measurements of aerosols and plant productivity. Their findings, published in Nature Geoscience, show that globally plant volatiles boost vegetation productivity by around 1.23 Pg of carbon per year — equivalent to around 10% of the world’s fossil fuel carbon emissions.

“Amazingly we found that by emitting volatile gases, forests are altering the Earth’s atmosphere in a way which benefits the forests themselves,” says Rap. “While emitting volatile gases costs a great deal of energy, we found that the forests get back more than twice as much benefit through the effect the increased diffuse light has on their photosynthesis.”

Source: Plants bounce light to forest floor – Physics World, 2019-04-01

New study identifies biomass harvesting techniques that have few long-term impacts

A set of newly published studies evaluated nearly forty years of data on the impacts of biomass utilization on soil, tree, and plant recovery and found minimal impact using certain forest harvesting techniques.

The experiments, initiated in 1974, were conducted by scientists from the U.S. Forest Service Rocky Mountain Research Station on the Coram Experimental Forest, located in Northwestern Montana. In order to evaluate the ecological consequences of large-scale biomass harvesting, scientists implemented three different tree removal techniques on the landscape – group selection (remove small groups of trees), clearcut (remove all timber), and shelterwood (retain some trees for shade and structure) – all using cable logging. On all three sites the soil was left relatively undisturbed from the harvesting and varying amounts of downed wood were left to promote soil organic matter and wildlife habitat. For some sites, prescribed fire was applied to reduce fuels and fire danger. Scientists then tracked these sites over 38 years to provide a contemporary look at the long-term impacts of biomass utilization on forest productivity (e.g., tree growth).

Source: New study identifies biomass harvesting techniques that have few long-term impacts | Rocky Mountain Research Station