Revegetation

We propose to establish an Arizona Copper Mining Company – University of Arizona (UA) research collaboration. The overarching goal of the revegetation cooperative is to provide enhanced technological capacity to the mining industry to establish self-sustaining ecosystems on a diversity of mine wastes and lands disturbed by mining activities. Specific revegetation goals are dependent on end-use objectives and local site conditions; however, all reclamation strategies aim to establish a self-sustaining ecosystem that facilitates carbon sequestration, dust control, and the prevention of water and wind driven erosion processes. The revegetation SOW addresses this goal through three specific research objectives. First, the revegetation cooperative will identify coupled above- and belowground metrics of ecosystem regeneration that can be used to quantify the revegetation progress and assess whether a specific site reclamation is progressing, stalled, or failing. The availability of quantitative metrics of the revegetation progress informs the need for management interventions that improve the cost-effectiveness of land reclamation strategies. These metrics also serve as tools to evaluate new revegetation strategies including: the significance of capping material quality and depth, the value of soil amendments, seeding methods and timing, seed mix composition, and the development of plant varieties specifically adapted to locally encountered environmental stress (drought, extreme pH, and elevated metal concentrations).  Second, we contend that belowground development of soil fertility and biodiversity is an essential component of the establishment of a self-sustaining ecosystem.  The revegetation cooperative assesses the impact of different revegetation strategies on the rate of belowground fertility development.  Finally, the revegetation cooperative addresses plant establishment on metal contaminated mine waste.  The revegetation cooperative will screen a broad diversity of native plant species to identify plants that can be used to either hyperaccumulate metals for metal extraction from metal-contaminated substrates or prevent metal uptake to aboveground plant parts and thereby phytostabilize metals onsite through metal sequestration in and around plant root tissue. A comprehensive data base of metal accumulation vs. exclusion patterns for native plants is critically needed by the mining industry to avoid revegetation of metal contaminated wastes with plant species that will pass the metal contaminants into the food chain; or conversely to specifically select for hyperaccumulating plant species for effective use in metal extraction and site clean-up.

Deliverables for participating industries:

• Initial planning meeting: Each participating industry will identify the specific substrate (tailings vs waste rock) to be evaluated and the specific environmental parameters or revegetation strategies to be addressed.
• Site and sample analysis: An annual site visit will be conducted to evaluate plant establishment (where applicable) and design the sample collection strategy to address the specific environmental variables identified in the initial planning meeting. A total of 50 samples will be collected from each property annually and analyzed with a uniform suite of biogeochemical tests. An annual report will be provided to each participating industry with soil analysis and site assessment results.
• Comparative assessment of biogeochemical indicators: Results from participating properties will be compared and the value of each biogeochemical indicator as a predictor for revegetation potential/success under the specific conditions established at each property will be evaluated. The comparative analysis will be summarized in an annual report available to all participants.
• Property specific progress report: If requested, an analysis of mine waste development as a plant supporting matrix will be conducted by evaluating vegetated and unvegetated materials. Plant establishment surveys can also be conducted on sites with variable years under vegetation to establish a metric of progress in plant community development. When applicable, a comparative assessment of matrix development and plant establishment under different treatments will be produced for a specific property.

Specific details of proposed collaboration

• A CESM Legal Membership Contract is signed with each participating company, renewable every three years. An associated annual financial agreement is signed that designates 1) the start date for the designated project, 2) the specific research cooperative, and 3) the mine site associated with the research project. Companies can sign multiple financial agreements associated with a CESM membership agreement to establish research initiatives at multiple mine sites.  
• A site evaluation and sample collection will occur once per year, renewable annually. Vegetated sites will be characterized according to plant cover, plant species diversity and root depth.
• Each of the 50 substrate samples will be characterized using the following analyses: pH, Electrical conductivity (EC), particle size distribution, total carbon (TC), total nitrogen (TN), total organic carbon (TOC), total sulfur, neutrophilic bacterial plate counts (NHC), substrate net acid producing potential (NAPP), molecular biology detection of soil indicator bacterial populations (for nitrogen fixation and ammonia oxidation populations).
• Fully operational CESM laboratory facilities and research personnel are currently available at the UA to support this collaboration.