Where to begin? That's completely false. Firstly, forests are thermoregulating and are efficient CO2 sinks because of their evaporative cooling (using water from roots to keep leaves at optimum photosynthetic temperature). So, it isn't 'trees' you want, it's forests. Second, more CO2 might change the growing conditions, but as it heats the planet, that cooling might not work as well (it does need water). Fires can take forests down to ash if weather cycles make flammable wood faster than the deadwood can decay, so... warming climate threatens forests.
That means FEWER trees, unless some seeds in the soil survive the inferno. One doesn't hug saplings.