Net Photosynthesis and Early Growth Trends of a Dominant White Oak (Quercus alba L.)

Abstract

ABSTRACrExamination of the relationship betwee photosnthesis an growth of a do I white oak (Quevcw alm L) tree hs shown that most greow processes were eer led or well aderway before the ests t of s t posve rates of net potosts Growth was intiated first In the root system (March 3), folowed by stem cambial grwth (March 26) and later by flower, kleaf an b grwth (April 10 The photosynthetic process of white oak has been investigated in several studies (3,9,14 in clay content with depth from a silty clay loam at 30 cm to a clay at 67 cm. The soil was fully hydrated at the beginning of this study.PLANT MATERIAL The study tree was a 19-m-tall white oak (59 years old) with a diameter of 33.5 cm at 1.3 m. Branches and leaves utilized in this study were restricted to the upper one-fourth of the crown to facilitate attachment of the cuvette and to reduce mutual shading.An earlier study with '4CO2 had shown within the crown of the study white oak tree that there was no statistical difference in photosynthetic potential between the bottom and the top of the crown (3). On each sampling date, a branch having three to five leaves was selected for study. The branch was arbitrarily selected to obtain a set of leaves which reflected the average leaf development observed for the upper portion of the crown on each sampling date. In addition, on 2 days (April 30 and May 1), expanding green shoots with leaves removed were selected for study. Shoots which provided the maximum amount of new tissue available to be enclosed in the cuvette were selected since the Ph.of this tissue was expected to be low.Descrition of Measurement SystemL Net photosynthetic rate of leaf and stem tissue was determined with an open system composed of a ventilated thermoelectric cuvette and Beckman (model 315) IRGA differential CO2 analyzer. CO2 concentrations of the supply gas to the cuvette were monitored with a Beckman (model 215) absolute analyzer. Water vapor was removed before entering both IRGAs with a condensor. Changes in water vapor concentration between the supply and the gas from the cuvette were determined with a dew point hygrometer (EGG model 880), and were used to estimate transpiration. A thermoelectric plate in the base of the cuvette provided the ability to vary leaf temperature from near 0 to 45 C (±1.5 C).

Phenological and growth patterns of the Mediterranean oak Quercus suber L.

“…The growth trends here described for this evergreen species are similar to those reported for a deciduous oak by Dougherty et al (1979), and it is likely that an equivalent below-ground dynamics occurs for Q. suber. Those authors observed that root and stem cambial growth were the first phenological events, ceasing by the time of leaf expansion, and resuming after leaves became a major exporter of photosynthate.…”

“…The rapid leaf emergence, expansion, and thickening observed in this study suggest not only a protection strategy against desiccation and herbivory (Mooney et al 1974), but also an opportune investment while water availability and climatic conditions are still suitable for maximum photosynthetic production (Dougherty et al 1979;Oliveira et al 1992). According to McLaughlin and McConathy (1979), most of the carbon was probably incorporated into new leaves and shoots during this period.…”

Environmental control of CO2 assimilation rates and stomatal conductance in five oak species growing under field conditions in Greece

“…On 7 May, the leaves were not fully enlarged, the assimilation rates of which were high. Others have noted that A in deciduous leaves approaches maximum values before leaves are fully expanded (Dougherty et al, 1979). The early development of photosynthetic capacity is especially advantageous for tree growth in a Mediterranean climate where the drought starts early.…”

Divergent carbon dynamics under climate change in forests with diverse soils, tree species, and land use histories

“…To more accurately reflect the growth response of tree species to changing temperature, parameters dictating the heat tolerance curve and optimal photosynthetic temperature for each tree functional group were updated. Empirical data on at least one species from each functional group was used and more when available (Ledig et al 1977, Dougherty et al 1979, Epron 1997, Jull et al 1999, Nedlo et al 2009, Turnbull et al 2001, Warren and Dreyer 2006, Weston and Bauerle 2007.…”