Physiological profiling of invasive plant species for ecological restoration of fly ash deposits.
Extensive gaps in invasive plant species research in terms of ecosystem distribution and impact are major barriers faced by global decision making bodies for scientific management of plant species invasions of native flora. Effective strategies need to be worked out which would enable simultaneous management and the use of invasive plant species for ecosystem restoration. For evaluating the photosynthetic potential of invasive plant species in restoration of degraded areas, exhaustive in situ leaf gas exchange and leaf chlorophyll fluorescence were undertaken on four plants found naturally colonizing on the fly ash deposits. The four invasive species screened for their physiological tolerances towards microclimatic and edaphic stresses in harsh fly ash deposits were: Typha latifolia, Saccharum spontaneum, Prosopis juliflora, and Ipomea carnea. Saccharum spontaneum was found to be most efficient in sequestering CO2 emissions which were reflected in its maximum net photosynthetic rate (A, 29.29 ± 0.46 μmolCO2 m-2s-1) and higher below ground biomass. Maximum water use efficiency (WUE) was observed in S. spontaneum (9.3 ± 0.5 mmolCO2 molH2O-1) among all the species owing to high carboxylation, the lowest transpiration rate (E, 3.15 ± 0.13 mmolH2Om-2s-1) and stomatal conductance (gs, 0.2 ± 0.004 molH2Om-2s-1) values supporting it's dense growth throughout the fly ash dumps in contrast to other three species. The study provides insights into the successful use of invasive plant species for their effective management and phytorestoration of fly ash dumps by transforming them into net carbon sinks which otherwise lack any native flora.