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Keywords:

  • aspect;
  • grassland;
  • juvenile plants;
  • Microlaena stipoides;
  • slope ;
  • volcanic cones

Summary

Two experiments were conducted to determine the establishment success of reintroducing Microlaena stipoides (pātītī, weeping rice grass) into existing high-fertility grassland on the volcanic cones of the Auckland Isthmus. The first experiment monitored the survival and development of juveniles planted in a factorial design including two planting densities, two slope classes and two aspects across three cones. Plant survival during establishment was consistently over 90%. Maximum M. stipoides cover after 2 years (>80%) was achieved on north-facing steep slopes (>25°) at the greater planting density (40 plants/m2). However, results were particularly idiosyncratic to specific cone/topographical combinations. The second experiment, on a flat site on one cone, monitored the survival and development of juveniles planted across four post-planting treatments designed to suppress resident vegetation recovery. Plant survival after 6 months was relatively low (50%), and none of the treatments achieved greater than 5% cover of M. stipoides after 1 year. The chosen post-planting treatments were unable to suppress vigorous recovery of competitive exotic grasses on a moist fertile site. Overall, juvenile planting was shown to be a potentially successful method of Microlaena establishment and could restore indigenous dominance to exotic grassland in this environment, but individual site factors and the high cost of establishment must be considered.