Photosynthesis in relation to leaf nitrogen and phosphorus content in Zimbabwean trees

Tuohy, Janet M.; Prior, Juliet; Stewart, George R.

doi:10.1007/bf00317582

Cited by 33 publications

(26 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This may have occurred because of the low peak growth light levels that we were able to supply to our plants in the greenhouse (up to 450 μmol m −2 s −1 ). The light‐saturated A a values we recorded (range: 1–13 μmol m −2 s −1 ) (Table S3) are similar to values recorded on savanna adults in the field [3–16 μmol m −2 s −1 (Tuohy, Prior & Stewart ; Eamus et al . ; Prado et al .…”

Section: Methodssupporting

confidence: 85%

Leaf adaptations of evergreen and deciduous trees of semi‐arid and humid savannas on three continents

et al. 2013

View full text Add to dashboard Cite

Summary1. Drought stress selects for a suite of plant traits at root, stem and leaf level. Two strategies are proposed for trees growing in seasonally water-stressed environments: drought tolerance and drought avoidance. These are respectively associated with evergreen phenology, where plants retain their leaves throughout the year, and deciduous phenology, where plants drop their leaves during dry seasons. Evergreen species are thought to have leaf traits supporting lower photosynthesis and transpiration rates, in order to conserve water during dry periods. 2.We evaluated 18 morphological, chemical and physiological leaf traits of 51 abundant savanna tree species that differed in leaf habit (deciduous and evergreen), selected from two climate types (semi-arid and humid) in three continents (Australia, Africa and South America) (annual rainfall range: 500-1550 mm), and grown in a common garden experiment. We hypothesised that evergreen species have more conservative water use and differ more across climate types than deciduous species because evergreen species are forced to endure extended water deficits during dry seasons. 3.Trait shifts between semi-arid and humid savannas did not differ between evergreen and deciduous species. 4. Evergreen species had similar assimilation rates but lower photosynthetic water-use efficiency (PWUE) than deciduous species, possibly to extend their leaf lifespans by protecting their photosynthetic machinery from overheating through evaporative cooling. 5.Species of humid and semi-arid environments did not differ with respect to assimilation rate or PWUE, but semi-arid species did have smaller leaf sizes and greater leaf potassium and phosphorus concentrations. These traits may enable semi-arid species to maximize growth during episodes of favourable moisture availability.6. Species from the three continents differed in their leaf traits. These probably reflect the greater proportion of evergreen species in Australia as compared to the other continents and generally infertile soils in the South American sampling sites compared to the wider fertility range in the African sites.7. Synthesis: Water stress in savannas does not select for more conservative water use, but may select for rapid adjustment to prevailing water conditions and for heat avoidance mechanisms.

show abstract

Section: Methodssupporting

confidence: 85%

Leaf adaptations of evergreen and deciduous trees of semi‐arid and humid savannas on three continents

et al. 2013

View full text Add to dashboard Cite

show abstract

“…2). A similarly high PFD for light saturation has been reported for upper canopy leaves of other tropical trees (Pearcy 1987;Tuohy et al 1991;Hogan et al 1995). Significantly greater regression slopes of oxygen evolution rates against incident light between 750 and 1900 µmol m -2 s -1 for PD leaves than for EW leaves also indicate their potential for exploitation of higher dry season light availability (Fig.…”

Section: Seasonal Leaf Phenotypesmentioning

confidence: 54%

Seasonal leaf phenotypes in the canopy of a tropical dry forest: photosynthetic characteristics and associated traits

1997

View full text Add to dashboard Cite

We evaluated the hypothesis that photosynthetic traits differ between leaves produced at the beginning (May) and the end (November-December) of the rainy season in the canopy of a seasonally dry forest in Panama. Leaves produced at the end of the wet season were predicted to have higher photosynthetic capacities and higher water-use efficiencies than leaves produced during the early rainy season. Such seasonal phenotypic differentiation may be adaptive, since leaves produced immediately preceding the dry season are likely to experience greater light availability during their lifetime due to reduced cloud cover during the dry season. We used a construction crane for access to the upper canopy and sampled 1- to 2-month-old leaves marked in monthly censuses for six common tree species with various ecological habits and leaf phenologies. Photosynthetic capacity was quantified as light- and CO-saturated oxygen evolution rates with a leaf-disk oxygen electrode in the laboratory (O) and as light-saturated CO assimilation rates of intact leaves under ambient CO (A). In four species, pre-dry season leaves had significantly higher leaf mass per unit area. In these four species, O and A per unit area and maximum stomatal conductances were significantly greater in pre-dry season leaves than in early wet season leaves. In two species, A for a given stomatal conductance was greater in pre-dry season leaves than in early wet season leaves, suggesting a higher photosynthetic water-use efficiency in the former. Photosynthetic capacity per unit mass was not significantly different between seasons of leaf production in any species. In both early wet season and pre-dry season leaves, mean photosynthetic capacity per unit mass was positively correlated with nitrogen content per unit mass both within and among species. Seasonal phenotypic differentiation observed in canopy tree species is achieved through changes in leaf mass per unit area and increased maximum stomatal conductance rather than by changes in nitrogen allocation patterns.

show abstract

“…In contrast, in the savannah woodlands typical of seasonal sub-humid tropical climates, there are substantial losses of N in annual grass fires (Nye & Greenland 1960), and for most trees N is more likely to be limiting (Vitousek 1984). For example, photosynthesis was positively correlated with leaf N concentrations in both NOD and non-NOD species in savannah woodland in Zimbabwe (Tuohy et al 1991). The validity of these broad generalizations about nutrient limitation must be in some doubt because the baseline data set is very limited, and some reports are contradictory.…”

Section: Introductionmentioning

confidence: 99%

Roles of Root Symbioses in African Woodland and Forest: Evidence from 15 N Abundance and Foliar Analysis

Högberg¹,

Alexander²

1995

The Journal of Ecology

View full text Add to dashboard Cite

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. This content downloaded from 128.235.251.160 on Sun, Summary 1 To gain insight into the nutrition of trees with ectomycorrhizas (ECM), VAmycorrhizas (VAM) or VAM plus N2-fixing legume root nodule symbioses (NOD) in tropical woodland and forest ecosystems, we measured foliar nutrient concentrations and 15N abundances in miombo woodland in Zambia (22 spp.) and in lowland rain forest in Cameroon (20 spp.). 2 In miombo woodland, confirmed NOD species had low 15N abundances (mean 15N = 0.2%o), high % N and high N:P ratios. Baphia bequaertii, a species thought likely to be NOD, shared these characteristics, but so did Cassia abbreviata which is less likely to be NOD. 3 Among VAM and ECM species in miombo there were, in general, positive correlations between 15N abundance and % N, and between % N and % P. Dominant ECM species (Caesalpinioideae-Dipterocarpaceae) had slightly higher % N, but not higher 15N abundance than VAM species. The 15N data do not agree with data on ECM and VAM species previously obtained from Tanzanian miombo. 4 In the rain forest, there were no large differences between the three symbiotic groups. For NOD species 15N was almost 4%o above that of atmospheric N2 and only slightly lower than that of non-NOD species. NOD species also had relatively high foliar % N. 5 Data on species composition, foliar 15N abundance and N:P ratios support the idea that N2-fixation carried out by N2-fixing trees is more important in the woodland than in the rain forest.

show abstract

Photosynthesis in relation to leaf nitrogen and phosphorus content in Zimbabwean trees

Cited by 33 publications

References 9 publications

Leaf adaptations of evergreen and deciduous trees of semi‐arid and humid savannas on three continents

Leaf adaptations of evergreen and deciduous trees of semi‐arid and humid savannas on three continents

Seasonal leaf phenotypes in the canopy of a tropical dry forest: photosynthetic characteristics and associated traits

Roles of Root Symbioses in African Woodland and Forest: Evidence from 15 N Abundance and Foliar Analysis

Contact Info

Product

Resources

About