Earth can sustain more terrestrial plant growth

Washington: Our planet can produce much more land-plant biomass -- the total material in leaves, stems, roots, fruits, grains and other terrestrial plant parts -- than previously thought, says new research.

The study recalculates the theoretical limit of terrestrial plant productivity and finds that it is much higher than many current estimates allow.

Estimates derived from satellite images of vegetation and modelling suggest that about 54 gigatons of carbon is converted into terrestrial plant biomass each year, the researchers report.

"This value has remained stable for the past several decades, leading to the conclusion that it represents a planetary boundary - an upper limit on global biomass production," said Evan DeLucia, a plant biology professor at University of Illinois.

But these assumptions don't take into consideration human efforts to boost plant productivity through genetic manipulation, plant breeding and land management, DeLucia added.

Such efforts have already yielded some extremely productive plants.

For example, in India, bamboo plantations produce about 40 percent more biomass than dry, deciduous tropical forests.

Some of these plants would not be desirable additions to native or managed ecosystems, DeLucia said, but they represent the untapped potential productivity of plants in general.

To reach this conclusion, the team used a model of light-use efficiency and the theoretical maximum efficiency with which plant canopies convert solar radiation to biomass to estimate the theoretical limit of net primary production (NPP) on a global scale.

This newly calculated limit was "roughly two orders of magnitude higher than the productivity of most current managed or natural ecosystems", the authors wrote.

"We are not saying that this is even approachable, but the theory tells us that what is possible on the planet is much, much higher than what current estimates are," DeLucia said.

"All I am saying here is that we are underestimating the productive capacity of plants in managed ecosystems," he concluded in a paper that was published in the journal Environmental Science and Technology.