Phytomining with Nickel and Rare Earth Element Hyperaccumulators: A Nature-Based Strategy for Critical Mineral Supply and Conservation with Prospects for the United States

The accelerating demand for nickel and rare earth elements (REEs) for batteries, renewable energy technologies, and advanced electronics is intensifying pressure on conventional mining, with profound implications for biodiversity, ecosystem integrity, and local communities. Phytomining—cultivating metal-hyperaccumulator plants to recover metals from soils—has emerged as a promising complementary approach that can simultaneously generate metal resources, remediate degraded lands, and deliver conservation co-benefits. Nickel phytomining is now approaching commercial deployment, supported by a diverse flora of more than 500 nickel-hyperaccumulator species and field trials demonstrating economically relevant yields of approximately 22.6–77 kg Ni ha−1 yr−1 on ultramafic and mine-affected soils. In parallel, recent discoveries of REE hyperaccumulator plants and advances in biomass processing, including rapid electrothermal calcination, have revitalized interest in REE phytomining as a sustainable alternative for critical mineral recovery. This review synthesizes current knowledge on the ecology, physiology, and agronomy of nickel and REE hyperaccumulators, with a focus on how their deployment in phytomining systems can contribute to biodiversity conservation, land restoration, and resource recycling. It identifies key research gaps in hyperaccumulator discovery, molecular mechanisms, soil–plant–microbe interactions, agronomic optimization, biomass processing, techno-economic assessment, and social science and governance. In addition, the paper presents a novel techno-economic assessment for Texas as a case study of U.S. deployment, and proposes a phased scouting protocol for discovering and domesticating new hyperaccumulator species. Together, these elements provide a framework for integrating phytomining into conservation planning and critical mineral strategies, particularly in the United States, where ARPA-E programs are beginning to target domestic phytomining supply chains.