Studies of both natural and managed ecosystems suggest that all sectors of the biosphere will be benefited by the ongoing rise in the air's CO2 content, with the greatest relative benefits going to those areas currently possessing the lowest growth potentials, due either to a lack of needed resources or the presence of environmental stresses. Wishing to reap these benefits now, however, many commercial greenhouse operators flood their facilities with extra CO2 and profit today from the added prowess that will be possessed by the plants of tomorrow, just as we currently reap the benefits - among which is an actual doubling of plant water use efficiency - that have resulted from the doubling of the air's CO2 content that has occurred since the peak of the last ice age some 18,000 years ago.
These ongoing CO2-induced enhancements of vegetative productivity and water use efficiency are major forces in helping ecosystems maintain their biodiversity; for with more primary production, more species are enabled to maintain their numbers at levels required to ensure their continued viability. In addition, it has recently been demonstrated that plants of different species share resources via fungal linkages among their root systems. And as the flows of water and nutrients through these fungal conduits typically move from plants that possess sufficient quantities of these substances to those that lack them, this phenomenon promotes coexistence and ecosystem species richness.