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Restoration of indigenous dominance in exotic grassland by the establishment of juvenile Microlaena stipoides plants

Authors

  • Mike Dodd,

  • Bruce Burns


  • This article describes part of a research programme conducted for the Auckland Council investigating the restoration of indigenous grassland vegetation on the Auckland volcanic cones.
  • Botanical nomenclature follows Ngā Tipu o Aotearoa – New Zealand Plants, http://nzflora.landcareresearch.co.nz/

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.

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