Differences in water‐use efficiency between Agathis australis and Dacrycarpus dacrydioides are genetically, not environmentally, determined

Abstract

Isotopic carbon ratios were measured in homogenised leaf litter and in sapwood of Agathis australis (kauri) and Dacrycarpus dacrydioides (kahikatea) trees growing together at ridge crest and valley sites in Northland, New Zealand. The discrimination (A) values for kauri were significantly less than for kahikatea, indicating a possibility of higher water‐use efficiency of kauri. Discrimination did not vary significantly in different environments, with each species showing similar values at several valley and ridge sites even at distant locations. It is concluded that the differences in A between kauri and kahikatea are the result of fundamental physiological differences between the species rather than resulting from site preferences. For both species, wood is significantly less depleted than leaf material.

Keywords:

• carbon isotope discrimination
• Agathis australis
• Dacrycarpus dacrydioides
• water‐use efficiency

Notes

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