D. Yakir et Y. Israeli, REDUCED SOLAR IRRADIANCE EFFECTS ON NET PRIMARY PRODUCTIVITY (NPP) AND THE DELTA-C-13 AND DELTA-O-18 VALUES IN PLANTATIONS OF MUSA SP, MUSACEAE, Geochimica et cosmochimica acta, 59(10), 1995, pp. 2149-2151
Biomass accumulation (annual net primary productivity, NPP) in a plant
ation of Musa sp., Musaceae is linearly correlated with solar irradian
ce (IR) between 100 and 32% of ambient levels (NPP = 0.82 IR + 20.42,
p < 0.01, for the normalized data). The irradiance effects are clearly
reflected in the delta(13)C values of leaf organic matter that are al
so Linearly correlated with irradiance levels (with a slope of 0.23 pa
rts per thousand for any 10% decrease in IR). We conclude that changes
in the organic delta(13)C values faithfully record the irradiance eff
ects on the plants photosynthetic capacity since they are not accompan
ied by changes in concentration and delta(13)C values of air CO2 or by
changes in the delta(18)O values of the leaf cellulose. The results p
rovide a unique, quantitative demonstration of (1) the importance of c
hanges in irradiance such as those associated with cloudiness and aero
sols for NPP and (2) the usefulness of the combined C-13, O-18 analysi
s for recording and interpreting these effects.