UC Merced

Quantifying terrestrial carbon (C) stocks in vineyards represents an important opportunity for estimating C sequestration in perennial cropping systems. Considering ~230,000 ha in California (8.2% of total land cultivated in CA) are dedicated to wine grape production, annual C capture and storage in woody biomass is substantial. In this study, destructive sampling was used to measure C stocks in the woody biomass of a 15-year-old Cabernet Sauvignon vines from a California Northern San Joaquin Valley vineyard. The objectives were to characterize C stocks in terms of allometric variation between biomass fractions of roots, aboveground wood, canes, leaves and fruit, and then test correlations between easy-to-measure variables such as trunk diameter, pruning weights and harvest index to vine biomass fractions. Carbon stocks were also estimated from the volume of biomass in mounds generated during vineyard removal, and compared with previous estimates of standing biomass.

Total vine C was estimated at 12.3 Mg C/ha, of which 8.9 Mg C/ha came from perennial vine biomass, whereas annual biomass was estimated at 1.7 Mg C/ha from leaves and canes and 1.7 Mg C/ha from fruit. High positive correlations were found between the diameter of the trunk and overall woody C stocks (r2 = 0.84), pruning weights and annual C stocks (r2 = 0.93), and between fruit weight and annual C stocks (r2 = 0.95). Carbon estimates in the mounds of vine biomass fractions wood, root and canes (10.25 Mg C/ha) were not significantly different than for individually measured vines (10.02 Mg C/ha).

This research demonstrates that allometric equations represent strong predictive power for C estimations due to high correlations and low error between these simple measurements and C stocks. Such equations, using information collected from vineyard management practices, could enable growers to estimate C stocks more easily and would facilitate managing C at a vineyard level. This might also provide the basis to calculate future C stock estimations, especially important considering the significance that C sequestration is taking in the production function of agro-ecosystems.