An adjustable tree jack configured for assembly and disassembly into smaller, hand-carried sub-assemblies for field portability including an adjustable jack stand compatible with a variety of jack mechanisms, and a selected jack mechanism. A representative jack stand includes a base, a lower frame removably connectible to the base, and a telescoping riser removably receivable by a riser receiver of the lower frame. The lower frame defines a slot and the telescoping riser includes a lifting rod removably receivable within the slot. The jack mechanism is removably capturable between a support bracket and the lifting rod for lifting and lowering the telescoping riser under load allowing the telescoping riser to be lifted under load causing lifting displacement of the telescoping riser with respect to the lower frame with the lifting rod traveling within the slot.