[RussianConservative]

Ok, I bite. Trees breath CO2, how it kill them? Sulfiric gas, I understand, CO2?

[Sabertooth]

Ok, I bite. Trees breath CO2, how it kill them? Sulfiric gas, I understand, CO2?

From the article...

Mammoth Mountain, a young volcano in eastern California, sits on the southwest rim of Long Valley Caldera. In 1994, scientists detected high concentrations of CO2 gas in the soil on Mammoth Mountain.

< -snip- >

Although leaves of plants produce oxygen (O2) from CO2 during photosynthesis, their roots need to absorb O2directly. The high CO2 concentrations in the soil on Mammoth Mountain are killing trees by denying their roots O2and by interfering with nutrient uptake. In the areas of tree kill, CO2 makes up about 20 to 95% of the gas content of the soil; soil gas normally contains 1% or less CO2.

[lepton]

Ok, I bite. Trees breath CO2, how it kill them?

Trees need O2 to respirate, however while exposed to sunlight, they use CO2 to produce sugars and such and release O2 as a by-product during the day (At night they cease to split CO2, as they no longer have an energy source, and instead absorb small quantities of O2 from the surrounding air).

The roots generally do not have chloroplasts or chlorophyll in significant quantities, and so don't engage in photosynthesis even during the day - they do, however, still need to respirate. Without an adequate source of O2, they will suffocate and die.