Global CO2 concentrations have increased at a rate of 2 ppm yr-1 over the last five years and as a result wilding conifer seed production is predicted to increase.  A recent study reports that the quantity of viable Pinus taeda seed increased (P = <.001) by 186% per unit basal area with elevated CO2 (Way D.E, et al 2010).  The study provides evidence, that despite similar seed mass for both ambient and elevated CO2 environments the seed quality of this woody species increased dramatically with enriched CO2

Way et al 2010 found that annual variability in seed quality across CO2 treatments was negatively correlated (r2 = -0.18, P = 0.0012) with potential evapotranspiration and suggested a summer drought effect on seed development was the likely reason for this. 

Way et al 2010 also argued that because of their findings and other reported differences in herbaceous and woody responses to elevated CO2 that woody species are likely to encroach more effectively into grassland and herbaceous communities. 

Extrapolating from their work suggests that seed viability of conifers in cooler environments, such as the NZ high country, may have increased by 0.5% per year over the last five and will continue to do so as CO2 increases because of greater allocation to reproduction components.