Architectural differences in saplings of temperate versus tropical angiosperms; consequences of the deciduous habit?

2005 ◽  
Vol 83 (11) ◽  
pp. 1391-1401 ◽  
Author(s):  
David A. King

The architecture of saplings of temperate deciduous species of the southeastern United States was compared with that of tropical evergreen species of Central America, Borneo, and northeastern Australia. The deciduous species were more planar in the understory than were the tropical species, because of (i) more planar leaf displays within branches, (ii) a high frequency of arching, plagiotropic main stems (associated with greater plasticity in crown symmetry in relation to light), and (iii) a lower height of first branching. The deciduous species also had more planar branches than did subtropical and temperate evergreen angiosperms. This greater planarity in temperate deciduous understories may be associated with the simultaneous positioning of most leaves during a single flush in the spring. In contrast, saplings in tropical understories typically bear multiple leaf cohorts and position new leaves at the peripheries of existing leaf displays. These results and those of other studies suggest that there are adaptive links between plant architecture and phenology. Other factors, such as latitudinal variation in sun angles, may influence crown shape in overstory trees, but did not seem to be involved here, possibly because the filtering effect of the canopy results in smaller latitudinal shifts in understory illumination angles during the growing season. Thus, by favouring the deciduous habit, the cold winters and warm, humid summers of the eastern deciduous biome of North America appear to have had a notable influence on sapling architecture.

2013 ◽  
Vol 39 (3) ◽  
Author(s):  
Roger Kjelgren ◽  
Daryl Joyce ◽  
David Doley

Understanding native habitats of species successful as subtropical and tropical urban trees yield insights into how to minimize urban tree water deficit stress experienced during monsoonal dry periods. Equatorial and montane wet forest species rarely subject to drought are generally absent in subtropical and tropical cities with pronounced monsoonal dry seasons. Species native to monsoonal dry forests appear to have wide environmental tolerances, and are successful as urban trees in many tropical cities. Monsoonal dry forest species have a tendency to be deep rooted to avoid drought, with leaf habits falling along an avoidance to tolerance spectrum. Dry deciduous species, typically found on more fertile soils, maximize growth during the monsoonal wet season with high photosynthesis and transpiration rates, then defoliate to avoid stress during the dry season. Evergreen tree species, typically found on less fertile soils, have a higher carbon investment in leaves that photosynthesize and transpire less year-round than do dry deciduous species. Dry deciduous tree species are more common urban trees than dry evergreen species explicitly due to more ornamental floral displays, but also implicitly due to their ability to adjust timing and duration of defoliation in response to drought. An empirical study of three tropical species exhibiting a range of leaf habits showed isohydric behavior that moderates transpiration and conserves soil water during drying. However, dry evergreen species may be less adaptable to tropical urban conditions of pronounced drought, intense heat, and limited rooting volumes than dry deciduous species with malleable leaf habit.


2005 ◽  
Vol 22 (1) ◽  
pp. 41-51 ◽  
Author(s):  
Amy Hallam ◽  
Jennifer Read

Tropical plants have been suggested to have higher levels of mechanical, chemical and biotic defences than temperate plants. However, comparisons have usually included deciduous species within the temperate group, which confounds the analysis since deciduous species are predicted to have a different strategy with respect to investment, nutrition and defence than evergreen species. In this study we examined levels of defence and nutrition in five evergreen species of Eucryphia occurring along a latitudinal gradient in eastern Australia, grown under common conditions in a glasshouse. From the resource-availability hypothesis we predicted the opposite gradient in defence investment, i.e. that lowest levels of defence will occur in tropical species with potentially high growth rates and annual productivity. However, we found an increase in cell wall content, total phenolics and tannin activity, and a decrease in protein availability, with decreasing latitude and/or increasing mean annual temperature. Hence, there was a trend of increasing defence (although not in leaf toughness) and declining nutritional quality towards the tropics. These latitudinal trends were recorded in both mature and expanding leaves. The same trends were observed in leaves of two species collected from the field, indicating that the results were not peculiar to the experimental growth regime. The latitudinal trend in defence did not support our prediction based on the resource availability hypothesis and may indicate that herbivore pressure is providing an overriding selection pressure, although there are alternative explanations.


2021 ◽  
Author(s):  
vivek pandi ◽  
Kanda Naveen Babu

Abstract The present study was carried out to analyse the leaf functional traits of co-occurring evergreen and deciduous tree species in a tropical dry scrub forest. This study also intended to check whether the species with contrasting leaf habits differ in their leaf trait plasticity, responding to the canopy-infestation by lianas. A total of 12 leaf functional traits were studied for eight tree species with contrasting leaf habits (evergreen and deciduous) and liana-colonization status (Liana+ and Liana−). In the liana-free environment (L−), evergreen trees had significantly higher specific leaf mass (LMA) and leaf dry matter content (LDMC) than the deciduous species. Whereas, the deciduous trees had higher specific leaf area (SLA) and mass-based leaf nitrogen concentration (Nmass). The leaf trait-pair relationship in the present study agreed to the well-established global trait-pair relationships (SLA Vs Nmass, Lth Vs SLA, Nmass Vs Lth, Nmass Vs LDMC, LDMC Vs SLA). There was no significant difference between L+ and L− individuals in any leaf functional traits studied in the deciduous species. However, evergreen species showed marked differences in the total chlorophyll content (Chlt), chlorophyll b (Chlb), SLA, and LMA between L+ and L− individuals of the same species. Deciduous species with the acquisitive strategy can have a competitive advantage over evergreen species in the exposed environment (L−) whereas, evergreen species with shade-tolerant properties were better acclimated to the shaded environments (L+). The result revealed the patterns of convergence and divergence in some of the leaf functional traits between evergreen and deciduous species. The results also showed the differential impact of liana colonization on the host trees with contrasting leaf habits. Therefore, liana colonization can significantly impact the C-fixation strategies of the host trees by altering their light environment. Further, the magnitude of such impact may vary among species of different leaf habits. The increased proliferation of lianas in the tropical forest canopies may pose a severe threat to the whole forest carbon assimilation rates.


2010 ◽  
Vol 28 (4) ◽  
pp. 197-202 ◽  
Author(s):  
Timothy L. Widmer

Abstract Phytophthora ramorum causes ramorum blight on Viburnum species, which are commonly grown as ornamentals. This study evaluated 24 different species or cultivars for susceptibility to P. ramorum. Whole plants were inoculated with an NA1 isolate of P. ramorum and placed in dew chambers at 20C (68F). After 5 days, the percentage of necrotic leaves for each plant and the percentage of necrotic area for each leaf were calculated. The percentage of necrotic leaves per plant ranged from 96.1% (V. tinus) to 7.9% (V. opulus ‘Notcutt’) and the percentage of necrotic leaf area ranged from 73.0% (V. × carlcephalum ‘Cayuga’) to 2.4% (V. trilobum ‘Wentworth’). In addition, six species or cultivars were evaluated for their susceptibility to a EU1 isolate of P. ramorum. The isolate had a significant effect on three of the six species or cultivars tested, although one isolate did not always yield the greatest necrosis. Evergreen species and cultivars had a higher percentage of necrotic leaves and higher percentage of necrotic leaf area than semi-evergreen or deciduous species and cultivars. All Viburnum species and cultivars showed some degree of susceptibility to P ramorum.


1970 ◽  
Vol 4 (6) ◽  
pp. 49-56
Author(s):  
Bharat B Shrestha ◽  
Yadav Uprety ◽  
Keshav Nepal ◽  
Sandhya Tripathi ◽  
Pramod K Jha

Phenological activities of eight woody species planted in Kirtipur (central Nepal) were examined, each for one dry season between September 2001 and June 2003. From Pressure Volume (P-V) analysis, we determined relative water content at zero turgor (RWCz), osmotic potential at zero turgor (Ψsz) and full turgor (Ψsf ), and bulk modulus of elasticity (ε) once a month through the course of dry season. Both evergreen species (Cotoneaster bacillaris Wall., Quercus lanata Sm., Ligustrum confusum Decne., Woodfordia fruticosa (L.) Kurz.) and deciduous species (Celtis australis Linn., Alnus nepalensis D.Don., Bauhinia variegata Linn. and Lagerstroemia indica Linn.) put out their new leaves during the dry summer when day length and temperature were increasing. Generally, bud break coincided with concentrated leaf fall during the dry summer and the leaf fall reduced total leaf area to its lowest value. The deciduous species were leafless for one to three months, followed by a prolonged period of leaf production and shoot elongation. Evergreen and deciduous species manifested distinct adaptive strategies to water deficit. Evergreens can reduce osmotic potential (Ψs) to its low value and maintain proper water potential (Ψ) gradient from soil to plant, which facilitates absorption of water during dry season. Elastic tissue in deciduous species is coupled with leaf shedding during the dry season; both factors may help maintain proper Ψs for new growth during dry period. One evergreen species (Woodfordia fruticosa) and three deciduous species (Celtis australis, Bauhinia variegata and Lagerstroemia indica) have inherently high dehydration tolerance due to their elastic tissue. During drought there has been osmotic adjustment in Quercus lanata, and elastic adjustment in Ligustrum confusum, Celtis australis and Lagerstroemia indica. Key words: Himalayas, Pressure Volume (P-V) curve, relative water content (RWC), osmotic adjustment, elastic adjustment Himalayan Journal of Sciences Vol.4(6) 2007 p.49-56


2016 ◽  
Vol 46 (12) ◽  
pp. 1475-1482 ◽  
Author(s):  
Tanaka Kenzo ◽  
Ayumi Tanaka-Oda ◽  
Yojiro Mastuura ◽  
Larry D. Hinzman

The morphological and physicochemical traits of leaves are important in terms of plant adaptation to various growth environments, because such traits play central roles in various functions including photosynthesis. We measured the toughness, mass per unit area (LMA), nitrogen content, and δ15N levels of the leaves of different life-forms of 39 broadleaf woody plants in interior Alaska. The plants were divided into three life-forms based on the maximum height of adult plants: understory (<1 m), small (≥1 m to <5 m), and canopy (≥5 m). Evergreen species accounted for a large proportion of understory woody plants (44%), whereas most small (87%) and canopy (100%) trees were deciduous. Higher LMA, increased toughness, and higher C-to-N ratios prolonged leaf life-span in evergreen species. We also evaluated the presence or absence of bundle-sheath extensions (BSEs), which contribute to the mechanical support of leaves and enhance photosynthetic ability by improving hydraulic properties. In total, 11 species (28%) had homobaric leaves (BSEs were absent) and 28 species (72%) had heterobaric leaves; these proportions are similar to those of woody plants of other temperate deciduous forests. The δ15N values reflected the presence of root symbionts such as ericoid mycorrhiza or Frankia sp. Our results suggest that leaf traits may affect both the life-form of the host plants and leaf longevity in both evergreen and deciduous species.


IAWA Journal ◽  
2014 ◽  
Vol 35 (4) ◽  
pp. 337-355 ◽  
Author(s):  
Alexander Scholz ◽  
Anke Stein ◽  
Brendan Choat ◽  
Steven Jansen

This paper explores the phenotypic plasticity of xylem in tropical trees in order to test the hypothesis that different leaf phenological patterns influence levels of xylem plasticity. Wood anatomy was studied in the wet-deciduous species Cordia alliodora (Ruiz & Pav.) Oken, the dry-deciduous species Tabebuia rosea (Bertol.) DC., and the evergreen species Ocotea veraguensis (Meisn.) Mez., collected from seasonally dry forest and tropical cloud forest in Costa Rica. Xylem plasticity and trait conservatism were examined by analysing the coefficient of variation (CV) and the relative distance plasticity index (RDPI) of xylem anatomical traits. The two deciduous species exhibited wider vessels, lower wood density, and higher Huber values than the evergreen species. Furthermore, intervessel connectivity was highest for the two deciduous species in seasonally dry forest compared to cloud forest, whereas the opposite was found for the evergreen species. Overall highest trait variability was found for all plants at the seasonally dry site. The evergreen species O. veraguensis had the highest plasticity values compared to the deciduous species. Highest plasticity was found for vessel composition index (vessel area/vessel number), whilestrongest trait conservatism was found for vessel diameter. In conclusion, our data indicate that evergreen O. veraguensis does not show less xylem plasticity than the two deciduous tree species studied.


2020 ◽  
Vol 47 (9) ◽  
pp. 779
Author(s):  
Débora di Francescantonio ◽  
Mariana Villagra ◽  
Guillermo Goldstein ◽  
Paula I. Campanello

Frost and drought are key stress factors limiting the growth and distribution of tree species. Resistance to stress involves energy costs that may result in trade-offs between different functional traits. Structures or mechanisms that can help to withstand stress imply differences in the carbon economy of the species. Although adaptive responses to frost and drought resistance are usually of a similar nature, they are rarely assessed simultaneously. We investigated these resistance mechanisms in 10 canopy tree species coexisting in the semi-deciduous subtropical forests of northern Argentina. We measured leaf lifespan, anatomical, photosynthetic and water relations traits and performed a thermal analysis in leaves to determined ice nucleation and tissue damage temperatures. Our results showed that evergreen and deciduous species have different adaptive responses to cope with freezing temperatures and water deficits. Evergreen species exhibited cold tolerance, while deciduous species were more resistant to hydraulic dysfunction and showed greater water transport efficiency. Further research is needed to elucidate resistance strategies to stress factors at the whole tree- and stand level, and possible links with hydraulic safety and efficiency among different phenological groups. This will allow us to predict the responses of subtropical forest species to changes in environmental conditions under climate change scenarios.


1984 ◽  
Vol 14 (1) ◽  
pp. 51-56 ◽  
Author(s):  
Peter J. Marchand

Standard analyses in dendrochronology were combined with estimates of wood production efficiency to clarify patterns of tree mortality in wave-regenerated fir forests (Abiesbalsamea (L.) Mill.). Results revealed important differences in radial growth and wood production per unit foliage area between dieback stands of young (37 years) and old (74 years) wave sites, indicating that wave mortality is not related to age nor restricted to trees of low vigor. Overstory trees in both young and old dieback areas are characterized by a high frequency of missing or partial rings in late years without significant change in wood production efficiency, suggesting that the primary cause for a decline at the wave edge is a mechanical loss of foliage rather than a decrease in photosynthetic efficiency. This is supported by a highly significant reduction (P = 0.005) in projected leaf area for dieback-zone trees. Tree-ring characteristics reported here are symptomatic of a carbon balance problem which may lead to tree death through a number of secondary causes.


2006 ◽  
Vol 54 (3) ◽  
pp. 249 ◽  
Author(s):  
M. Kohout ◽  
J. Read

Deciduous species of Nothofagus tend to replace evergreen Nothofagus at the highest altitudes. We investigated whether deciduous Nothofagus species have higher maximum rates of net photosynthesis (Pmax) and specific leaf area (SLA) than evergreen species and whether there is an increasing photosynthetic advantage (e.g. higher Pmax) in deciduous species relative to evergreen species with increasing altitude that might explain their replacement of evergreen species. Net photosynthesis was investigated in (1) five deciduous and five evergreen species of Nothofagus grown in a common environment and (2) two co-occurring species, N. gunnii (Hook.f.) Oerst. (deciduous) and N. cunninghamii (Hook.) Oerst. (evergreen), across a range of altitudes in Tasmania. In the first experiment, the maximum rate of net photosynthesis per leaf mass (Pmax, mass) and SLA were higher in deciduous species, whereas the maximum rate of net photosynthesis per leaf area (Pmax, area) did not differ between leaf habits. However, in the field-based study, both mass- and area-based Pmax were higher in N. gunnii than N. cunninghamii across all sites. The high Pmax, mass of deciduous species may provide a competitive advantage at higher altitudes by maximising carbon gain during the growing season. However, in the study of sympatric populations of N. gunnii and N. cunninghamii there was no evidence of increasing photosynthetic advantage of the deciduous N. gunnii with increasing altitude.


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