Effect of soil moisture on Chionochloa australis, C. rubra, and Festuca novae‐zelandiae water‐use

Abstract

The water‐use of three widespread New Zealand tussock species, Chionochloa australis, C. rubra, and Festuca novae‐zelandiae, was compared at five soil moisture levels, ranging from dry to waterlogged (19% to 106% relative saturation of porosity), in a glasshouse study. Water‐use for all species increased with soil moisture supply until complete saturation, and was significantly related to live shoot biomass. Chionochloa australis water‐use per unit weight of live shoot tissue was greater than that of the other species at low soil moisture supply. This is consistent with its restricted distribution to the high‐rainfall penalpine zone of the South Island axial ranges and suggests the hypothesis that inability to restrict transpiration loss may be a causal factor determining its range. The water‐use physiology of C. rubra and Festuca novae‐zelandiae are consistent with their wider ecological distributions.

Keywords:

• soil moisture
• Chionochloa australis
• Chionochloa rubra
• Festuca novae‐zelandiae
• water‐use;