[GRASS-user] aggregating or totaling values by patch size

Hi all,
i have 30m cell areas where i have a value for each cell representing a particular landscape characteristic (i.e. biomass)
i want to find the total of those value (biomass) by 800m cells, i.e. what the total biomass is by 800m cells rather than by each 30m cell.
does anyone know how to aggregate the 30m up to 800m?

i have created a 800m cell map - which i think i can use as the base map with r.average to get the average values from the 30m cover map, but i don’t know how to get a total rather than an average.

if anyone has suggestions, i’d really appreciate it.
Janet