Diurnal changes in leaf gas exchange characteristics in the uppermost canopy of a rain forest tree, Dryobalanops aromatica Gaertn. f.

Forest Environment Division, Forestry and Forest Products Research Institute, P.O. Box 16, Tsukuba Norin Danchi, Ibaraki 305, Japan.
Tree Physiology (Impact Factor: 3.66). 10/1996; 16(9):779-85. DOI: 10.1093/treephys/16.9.779
Source: PubMed

ABSTRACT Dryobalanops aromatica Gaertn. f. is a major tropical canopy species in lowland tropical rain forests in Peninsular Malaysia. Diurnal changes in net photosynthetic rate (A) and stomatal conductance to water vapor (g(s)) were measured in fully expanded young and old leaves in the uppermost canopy (35 m above ground). Maximum A was 12 and 10 micro mol m(-2) s(-1) in young and old leaves, respectively; however, because of large variation in A among leaves, mean maximum A in young and old leaves was only 6.6 and 5.5 micro mol m(-2) s(-1), respectively. Both g(s) and A declined in young leaves when T(leaf) exceeded 34 degrees C and leaf-to-air vapor pressure deficit (DeltaW) exceeded 0.025, whereas in old leaves, g(s) and A did not start to decline until T(leaf) and DeltaW exceeded 36 degrees C and 0.035, respectively. Under saturating light conditions, A was linearly related to g(s). The coefficient of variation (CV) for the difference between the CO(2) concentrations of ambient air and the leaf intercellular air space (C(a) - C(i)) was smaller than the CV for A or g(s), suggesting that maximum g(s) was mainly controlled by mesophyll assimilation (A/C(i)). Minimum C(i)/C(a) ratios were relatively high (0.72-0.73), indicating a small drought-induced stomatal limitation to A and non-conservative water use in the uppermost canopy leaves.

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    • " relationship is similar to previously published results on a wide variety of species , including several crop grasses ( Monje and Bugbee 1992 , Markwell et al . 1995 , Mulholland et al . 1997 , Uddling et al . 2007 ) , forbs ( Monje and Bugbee 1992 , Markwell et al . 1995 , Uddling et al . 2007 , Ling et al . 2011 ) , and woody trees and shrubs ( Ishida et al . 1996 , Netto et al . 2002 , Netto et al . 2005 , Uddling et al . 2007 , Hawkins et al . 2009 , Mielke et al . 2010 ) . The SPAD - 502 Chl meter depends on transmission of light through a leaf , which saturates at higher Chl concen - trations . In particular , sand bluestem had a SPAD index much higher than should be expected based on extract"
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    ABSTRACT: Leaf chlorophyll (Chl) concentration can be an indicator of plant health, including photosynthetic potential and nutrient status. In some cases, this measure can indicate the degree to which plants are water-stressed. Traditional methods of measuring Chl concentration have involved a destructive sampling technique: extraction and spectrophotometric analysis. A compatible nondestructive method to measure leaf Chl concentration exists and applies transmittance spectroscopy to plants with a Minolta SPAD-502 meter. These techniques were evaluated by comparing leaf Chl concentration in big bluestem (Andropogon gerardii). Leaves were sampled from plants representing three ecotypes (originating from Central Kansas, Eastern Kansas, and Illinois, USA) and two cultivars of A. gerardii growing in Hays, Kansas, USA. Leaf Chl concentration was measured using nondestructive and destructive techniques. We documented a saturating relationship between destructively measured leaf Chl concentration and SPAD index resulting from a decelerating change in SPAD index as Chl concentration increased. The comparison of A. gerardii ecotypes and cultivars demonstrated highest Chl concentration in the ecotype and cultivar from areas with historically low precipitation, Central Kansas and A. gerardii var. hallii, respectively. A high ratio of Chl a to Chl b is an index of drought adaptation and was also manifested in A. gerardii from drier regions. Thus, drought-adapted ecotypes and cultivars might be able to maintain high photosynthetic productivity and protect photosystem II during dry periods. Conversely, the ecotypes and cultivar originating from areas with higher precipitation had lower leaf Chl and a lower Chl a/b ratio.
    Photosynthetica 10/2014; DOI:10.1007/s11099-014-0057-2 · 1.41 Impact Factor
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    • "Even in tropical rain forest, with abundant water available (Mabberley 1992; Whitmore 1998), the canopy surface usually experiences severe water deficits during the daytime as a result of high temperature and irradiation (Walter 1973) and hydraulic constraint on the transport of water from roots to leaves (Ryan and Yoder 1997; Koch et al. 2004). Canopy species, therefore, undergo a midday depression (Aylett 1985; Koch et al. 1993; Meinzer et al. 1993; Kenzo et al. 2003; Pons and Welschen 2003; Brodribb and Holbrook 2004; Zhang et al. 2009) to reduce their water consumption (Aylett 1985; Ishida et al. 1996). Despite such regularly occurring water deficits, canopy species seldom suffer serious or fatal long-term water stress under normal annual climate conditions. "
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    ABSTRACT: By use of tree-tower and canopy-crane systems we studied variations in the water use, including transpiration, stomatal conductance, and leaf water potential, of the uppermost sun-exposed canopy leaves of four emergent dipterocarp species in an aseasonal tropical rain forest in Sarawak, Malaysia. Midday depression in stomatal conductance and leaf water potential was observed in all the species studied. Interspecific differences were clearly observed in the maxima of transpiration rates and stomatal conductance and the minima of leaf water potential among the four dipterocarp species. These interspecific variations were closely related to wood density and to factors affecting ecological patterns of distribution. Specifically, Shorea parvifolia and S. smithiana, both of which have a relatively low wood density for Dipterocarpaceae and are found on clay-rich soil, had a high transpiration rate in the daytime but had a large midday depression and a low leaf water potential. In contrast, Dryobalanops aromatica, which has a high wood density and is found in sandy soil areas, consumed less water even during the daytime. Dipterocarpus pachyphyllus, which has a high wood density and is found on clay-rich soil, stood intermediate between Shorea and D. aromatica in leaf water use. The two Shorea species had higher mortality than the others during the severe drought associated with El Niño in 1998, so daily pattern of leaf water use in each dipterocarp species might be correlated with its susceptibility to unusual drought events.
    Journal of Forest Research 08/2011; 17(4). DOI:10.1007/s10310-011-0303-4 · 0.78 Impact Factor
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    • "In this study, we present in situ results on leaf gas exchange rates in response to external environmental conditions and in association with possible underlying physiological mechanisms for a deciduous tree species of poorly studied but extensive African dry woodlands. For deciduous trees in such dry woodlands, diurnal leaf gas exchange patterns might follow similar qualitative patterns to trees of temperate forests or wet tropical rain forests (Weber and Gates 1990, Ishida et al. 1996, Souza et al. 2008): a typical hump-shaped pattern in transpiration and photosynthesis, with a possible midday depression or a gradual decline after morning peaks in gas exchange in temperate (Bassow and Bazzaz 1998) and dry tropical savanna (Eamus et al. 1999). "
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    ABSTRACT: A conceptual model was tested for explaining environmental and physiological effects on leaf gas exchange in the deciduous dry tropical woodland tree Boswellia papyrifera (Del.) Hochst. For this species we aimed at (i) understanding diurnal patterns in leaf gas exchange, (ii) exploring cause-effect relationships among external environment, internal physiology and leaf gas exchange, and (iii) exploring site differences in leaf gas exchange in response to environmental variables. Diurnal courses in gas exchange, underlying physiological traits and environmental variables were measured for 90 trees on consecutive days at two contrasting areas, one at high and the other at low altitude. Assimilation was highest in the morning and slightly decreased during the day. In contrast, transpiration increased from early morning to midday, mainly in response to an increasing vapor pressure deficit (VPD) and gradual stomatal closure. The leaf water potential varied relatively little and did not influence gas exchange during the measurement period. Our results suggest that the same cause-effect relationships function at contrasting areas. However, leaves at the higher altitude had higher photosynthetic capacity, reflecting acclimation to higher light levels. Trees at both areas nevertheless achieved similar leaf assimilation rates since assimilation was down-regulated by stomatal closure due to the higher VPD at the higher altitude, while it became more light limited at the lower altitude. Gas exchange was thus limited by a high VPD or low light levels during the wet season, despite the ability of the species to acclimate to different conditions.
    Tree Physiology 07/2011; 31(7):740-50. DOI:10.1093/treephys/tpr067 · 3.66 Impact Factor
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