Diel changes of atmospheric CO₂ concentration within, and above, cryptogam stands in a New Zealand temperate rainforest

Abstract

Atmospheric CO₂ levels were determined (at 2 m height) in the rainforest and in a clearing outside the forest, during spring (November) 1991, Urewera National Park, New Zealand. CO₂ levels within the forest were 30 ppm higher and showed a more variable diel pattern (range up to 70 ppm) than outside the forest. CO₂ levels were generally higher at night than during the day. Detailed measurements were made at several sites at a depth of 25 mm in the phylloplane of three moss species and under, or between, the thalli of four lichen species. Mean levels were 50% (moss phylloplane) and 10% (lichen thalli) higher than the levels in the clearing and, in 80% of sites, also higher than air within the rainforest. The diel pattern of the CO2 concentration at each of the sites was not predictable from measurements of CO₂ in the bulk air of the forest. High levels of CO₂ may be important in elevating photosynthetic rates of mosses and, to a lesser extent, lichens in the field.

Keywords:

• elevated CO₂
• phylloplane
• lichen
• bryophyte
• photosynthesis
• respiration
• rainforest