The influence of soil amendments on a native wildflower seed mix in surface mine restoration

With a multitude of physical, biological, and chemical soil characteristics disrupted or degraded during surface mining, it is challenging to achieve proper reclamation, much less restoration, post-mining. We sought to assess the potential of a native wildflower seed mix (NWSM) to establish and achieve high vegetative coverage in the first season using soil amendments. We also evaluated the influence of amendments on community composition and soil quality. In May 2018, we seeded a NWSM on a surface mine in experimental plots treated with either inorganic fertilizer, spent mushroom compost, or left untreated. Plant coverage and community composition within experimental plots were assessed in October 2018. Soil samples were collected at the beginning and end of the season to identify potential changes in organic carbon, nitrogen availability, bulk density, and pH. First-season vegetation results indicate that soil amendments may not be ecologically necessary or economically sensible for initial revegetation using a NWSM. Unamended plots surpassed compost-amended plots and equaled or surpassed fertilizer-amended plots in coverage, species richness, and proportion of seedlings present that originated from the mix. However, results from soil analyses suggest that compost may be beneficial to meeting surface mine restoration goals by improving important soil characteristics, such as percent organic matter, labile carbon, nitrate content, and pH, that could aid ecosystem recovery. Given the high degree of heterogeneity both within and between surface mines, future work should focus on identifying initial soil characteristics that could enable land managers to meet both reclamation and restoration goals using a NWSM.