Aboveground biomass in three Sonoran Desert communities: Variability within and among sites using replicated plot harvesting

Total aboveground biomass (TAGB) values are reported for the first time for the Sonoran Desert. Harvesting of replicated plots in three sites differing in geomorphology and vegetation structure allowed the statistical measurement of spatial variability within and among sites. Linear, power log-transformed, and power non-linear regressions were used to relate TAGB with plant metrics. Canopy volume explained the largest proportion of TAGB variance (r2 = 0.74–0.94) in the three models. All models were highly significant, but the non-linear was more robust, had a better distribution of residuals, and did not require data back-transforming, allowing the accurate estimation of biomass at the plot level using simple measurements of vegetation. TAGB ranged from 6.99 Mg ha−1 (Plains) to 29.24 Mg ha−1 (Arroyos) in the desertscrub, and was intermediate in the thornscrub (Hillsides: 13.03 Mg ha−1). Within-site variability of TAGB was highest in the Plains and lowest in the Hillsides. The weighted mean AGB was 16 Mg ha−1. Assuming a 1:1 root:shoot ratio, average total biomass could be 32 Mg ha−1. This remarkable value sets the Sonoran Desert as a potential reservoir of up to 4.4% of the total world deserts plant biomass in less than 1% of the deserts’ global area.