Plant Propagation for Environmental Offset Planting: A Case Study of Endangered Pomaderris clivicola and Near-threatened Bertya pedicellata

Abstract

Background: Environmental offset programs for threatened plant species can be limited by the capacity to propagate sufficient plants for establishing offset plantations. This study describes the use of clonal propagation techniques for an offset program that propagated two species impacted by a landslide and road works. Materials and Methods: Cuttings were collected from Pomaderris clivicola (Rhamnaceae) and Bertya pedicellata (Euphorbiaceae) on 9 and 7 occasions, respectively. Shoots were also initiated into tissue culture. Results: Both species proved extremely difficult to propagate from cuttings and tissue culture. Rooting frequencies for P. clivicola cuttings were 4.3%. Repeated harvests of cuttings from the impacted plant population over more than 2 years eventually provided most of the P. clivicola plants required for the offset planting. However, the offset population of P. clivicola also had to be supplemented with some plants produced by tissue culture and with one plant that was excavated from the impacted population. Rooting frequencies for B. pedicellata cuttings were only 1.3%. A combination of cutting propagation and tissue culture did not produce sufficient B. pedicellata plants for the offset planting, but the offset population was supplemented with 27 plants that were excavated during road works. Conclusion: Success in producing the offset plants depended ultimately on a combination of (a) Cutting propagation, (b) Tissue culture propagation and (c) Whole plant excavation and translocation. This case study highlights challenges and successes in propagating poorly-known species for an environmental offset program within a short timeframe and with little prior knowledge of suitable propagation methods.; ;