From a selection of web sources, the bulk density of mulch ranges from about 850 lbs/yd³ for a composite type to about 450 lbs/yd³ for bark mulch. 2,000 lb / 850 lb/yd³ = 2.35 yd³ 2,000 lb / 450 lb/yd³ = 4.4 yd³ So I'd guess anywhere between 2.4 to 4.4 yd³.