Ecological Thresholds as Constraints to the Growth and Survival of Woody Tree Species in Degraded Grassland in the South Island's Dryland Zone

Posted December 2013

Location: New Zealand

Organization: School of Forestry, University of Canterbury

Photo 1 (top left): Rank grass cover before start of project 
Photo 2 (top right): Spraying of rank grass before planting native seedlings


Photo 3 (bottom left): Mulch used as one of the treatments
Photo 4 (bottom right): Irrigated plot, another treatment

New Zealand’s dryland zone contains some of the country’s most endangered ecosystems and is also the least well protected. Natural regeneration of native forest and shrubland species is often limited by several environmental and anthropic factors that affect the establishment and growth of seedlings. This research is focusing on better understanding some of these factors and how they can be manipulated to enhance restoration success. The research is being undertaken at five sites from North Canterbury to the Mackenzie Basin, all of which were previously farmed and are now dominated by either a rank growth of exotic grasses or highly degraded short tussock grassland. 

Several treatments were established to better understand the factors limiting growth of native woody plants. At the rank grass sites the effect of ground treatments: cultivation (C), mulch (M), herbicide spraying (H) and shade (S) are being investigated. At the two degraded short tussock grassland sites, the effect of shade, irrigation and grazing are being investigated. Seedling growth is being followed for two years along with soil physical and chemical properties, and plant physiology. The trials were implemented in the summer of 2012 and data will be collected until April/2014.

For further details and information, please contact: 

Anna Paula Rodrigues

Forestry PhD Candidate
NZ School of Forestry
College of Engineering 
University of Canterbury

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