Gas exchange characteristics of Pinus canariensis needles in a forest stand on Tenerife, Canary Islands

Abstract

Gas exchange characteristics and chlorophyll fluorescence of the Canarian endemic pine (Pinus canariensis) were measured during the day for a year in a field stand on Tenerife, Canary Islands, Spain. Diurnal tendencies of gas exchange were variable depending on ambient conditions. In general they paralleled photosynthetic photon flux density with only one peak at midday, except on summer days with high air vapour pressure deficit (VPD), when needles exhibited a severe midday depression of CO 2 assimilation rate (A), in parallel with a reduction of stomatal conductance (g s ). The internal CO 2 concentration tendencies during the day suggest that stomatal closure was the main cause of the midday depression of photosynthesis. Chlorophyll fluorescence data corroborate this assertion, with the parameter F v /F m reaching high values throughout day and year. P. canariensis living in the sub-tropic exhibited high values of A (maximal A value of 17 mol m 2 s 1 ) and high optimal needle temperature for photosynthesis (25C) which were at the upper limit of the values given for conifers and similar only to data obtained for some pine species adapted to habitats at similar latitudes. g s was reduced to half when VPD attained 40 mbar, allowing this pine to have high A/g s values during high evaporative demand conditions.

Ontogenetic differentiation between Mediterranean and Eurasian pines (sect. Pinus) at the seedling stage

“…On the other hand, differences in cuticular transpiration between juvenile and adult leaves, associated to the different rates of development have been found in the same species studied in this paper, such that the more delayed heteroblastic change is associated to higher resistance of secondary needles to water loss compared to primary needles ). In addition, primary needles are generally more sensitive to frost damage ), but probably have a higher photosynthetic efficiency due to their higher proportion of photosynthetic tissues (Bormann 1955;Peters et al 2003). Therefore, it seems plausible that delayed heteroblastic change might have selected in drought-tolerant pines to construct drought-resistant foliage and, in some cases, a massive stem and a strong root system (like in P. canariensis).…”

Influence of canopy position, needle age and season on the foliar gas exchange of Pinus canariensis

“…The mean relative humidity of the air is 52% and the annual sum of precipitation ranges from 460 (Aboal et al 2000) to 930 mm (Peters et al 2003). Opposite to the typical Mediterranean climate, summer drought is often mitigated by high relative humidity of the air and high frequency of clouds due to the northeast trade winds.…”

“…Furthermore, canopy transpiration of Pinus canariensis has been shown to be maintained throughout the whole year (Luis et al 2005). However, despite few studies on the gas exchange characteristics of the foliage (Wieser et al 2002a, b;Peters et al 2003), no studies have focused on the impact of canopy position and needle age on the seasonal course of net CO 2 uptake of Weld grown Pinus canariensis trees throughout an entire year. Although such studies are rare (Schulze et al 1977;Troeng and Linder 1982;Matyssek 1985;Teskey et al 1995;Wieser 2004), they provide insights into environmental limitations (Strain et al 1976;Maier and Teskey 1992;Teskey et al 1995;Ellsworth 1999Ellsworth , 2000.…”

Effects of drought on needle anatomy of Pinus canariensis

“…In conclusion, the multitude and flexibility of needle morphology and anatomy together with needle physiology (Wieser et al 2002;Peters et al 2003) and particularities in stem (fire resistant) and root systems (deep roots) make P. canariensis a species which has an extraordinary wide ecological amplitude (Blanco et al 1989;Schütt et al 1995;Kunkel 1987).…”