Effects of light regime on the growth and physiology of Pentaclethra macroloba (Mimosaceae) in Costa Rica

1985 ◽  
Vol 1 (4) ◽  
pp. 303-320 ◽  
Author(s):  
Steven F. Oberbauer ◽  
Boyd R. Strain
Keyword(s):  
Costa Rica ◽  
Stomatal Density ◽  
Structural Characteristics ◽  
Sudden Change ◽  
Light Level ◽  
Leaf Damage ◽  
Growth Responses ◽  
Pentaclethra Macroloba ◽  
Partial Shade ◽  
Treefall Gap

ABSTRACTSeedlings of Pentaclethra macroloba (Willd.) Kuntze, a dominant, shade-tolerant species of tropical moist forest in Costa Rica, were raised under three light conditions to assess their acclimatization and growth responses to irradiance. The light environments used were full sun, partial shade (25% of full sun), and full shade (1% of full sun). To test the effect of a sudden change in light level such as would occur in the event of a treefall gap, the seedlings in the above conditions were switched between environments after two months and grown for an additional 1.5 months. Plants in full sun and partial shade had similar total weight; switching between the two environments had no effect on biomass. Plants switched from full sun and partial shade to full shade had negative growth as a result of negative CO2, flux and leaf abscission. Plants transferred from full shade to full sun had lower growth rates than those switched from full shade to partial shade because of severe leaf damage in full sun. The previous environment significantly affected the response of most growth and size characteristics to the present environment. Maximum photosynthesis changed only 30% in response to light level during growth. However, large changes in other photosynthetic and structural characteristics were found. Leaves developed in full shade had lower respiration, leaf thickness, and stomatal density and higher apparent quantum yield, specific leaf area, and chlorophyll content than leaves from full sun. Osmotic potentials were similar between treatments. Despite only small changes in maximum photosynthesis, acclimatization to extreme shade or sun rendered leaves unsuitable for large changes in environment. Consequently, in the event of a large treefall gap, plants already present in the understory will require a substantial period of adjustment before they respond to the increase in light.

La respuesta compensatoria de Pentaclethra macroloba ante tratamientos antagónicos: la fertilización y la defoliación

2019 ◽  
Author(s):  
Alejandra Pérez Enríquez ◽  
Roberto Cordero ◽  
Elizabeth Braker
Keyword(s):  
Costa Rica ◽  
Pentaclethra Macroloba

La combinación de rasgos como la fijación de nitrógeno en plantas tropicales con otros rasgos como disponibilidad nutricional podría incidir en el éxito de algunas especies para su establecimiento y desarrollo. Otras interacciones como la herbivoría podrían cambiar sutilmente estas relaciones y llegar a ser relevantes para su éxito ecológico. Sometimos brinzales de Pentaclethra macroloba (Gavilán, Fabaceae) en macetas, con y sin adición de nutrientes y a la interacción con defoliación controlada (herbivoría artificial), en el sotobosque secundario dentro de un bosque de Sarapiquí, Costa Rica. La biomasa total muestra una fuerte compensación neta y la defoliación indujo una mayor asignación al follaje. La fertilización siempre resultó en menos asignación a nódulos. La esbeltez respondió a ambos factores de manera sinergística. Sugerimos que la herbivoría puede ocasionar cambios importantes en la manera en que las especies asignan sus recursos en concordancia con sus simbiosis y la disponibilidad de nutrientes.

Effects of simulated acid rain on the growth of five Brazilian tree species and anatomy of the most sensitive species (Joannesia princeps)

2005 ◽  
Vol 53 (8) ◽  
pp. 789 ◽  
Author(s):  
Luzimar Campos da Silva ◽  
Aristéa Alves Azevedo ◽  
Eldo Antônio Monteiro da Silva ◽  
Marco Antonio Oliva
Keyword(s):  
Acid Rain ◽  
Tree Species ◽  
Leaf Blade ◽  
Woody Species ◽  
Leaf Damage ◽  
Growth Responses ◽  
Foliar Injury ◽  
Sensitive Species ◽  
Abaxial Epidermis

Seedlings and young saplings of some woody species were exposed to simulated low-pH acid rain, in order to develop a response screening for tropical tree species by determination of the symptoms of foliar injury and growth responses, as well as to identify anatomical alterations in the leaf blade of the most sensitive species. Gallesia integrifolia (Spreng.) Harms, Genipa americana L., Joannesia princeps Vell., Mimosa artemisiana Heringer & Paula and Spondias dulcis Forst.f. were exposed daily to 20 min of acid rain, pH 3.0, for 10 consecutive days. The degree of leaf damage and the anatomical alterations observed were efficient parameters to determine the sensitivity to acid rain. At the end of the experiment J. princeps was the most sensitive species as determined by foliar injury and seedling growth. The degree of leaf damage was similar among the seedlings, except in S. dulcis, which showed reduced percentage of foliar injury. Necrotic and chlorotic spots on the leaf blade occurred. In the most sensitive species, J. princeps, necrotic blade tissues showed accumulation of phenolic compounds, hypertrophy and collapsed cells. Most of the structural alterations were observed in the adaxial epidermis, the palisade parenchyma and spongy parenchyma and the abaxial epidermis. Long-term experiments with seedlings of S. dulcis and saplings of G. integrifolia are suggested, to characterise the response of these species that presented fewer symptoms but whose growth was affected under acid rain.

Numerical and Experimental Investigation of Transient Response of Primary Surface Recuperator Due to Flow Rate Step

2008 ◽  
Author(s):  
Zhenyu Liu ◽  
Yongkang Su ◽  
Huier Cheng
Keyword(s):  
Heat Exchanger ◽  
Transient Response ◽  
Flow Rate ◽  
Solid Wall ◽  
Structural Characteristics ◽  
Sudden Change ◽  
Transient Behavior ◽  
Temperature Transient ◽  
Rate Step ◽  
Comparative Results

Temperature transient response of a primary surface recuperator (PSR) is investigated when mass flow rate is subjected to a sudden change. Based on the conservation theorem of energy and structural characteristics of PSR, its unsteady differential equations about the transient temperatures of fluids and solid wall in the recuperator are presented. The numerical results are validated by comparison against the experimental data. The influence of flow rate step magnitude on the transient behavior is studied by maintaining the initial steady states. The influence of the thickness of the corrugated heat transfer foils in the PSR on the temperature transient response is also discussed. The comparative results show the low-weight PSR has much more advantages in transient response than traditional heat exchanger because its time constant of solid wall is much less than shell-tube or plate-fin heat exchanger. PSR is very fit for application to the marine or vehicle gas turbine engine that works under the changeful conditions.

scholarly journals Bird Assemblage Recovery in a Chronosequence of Tropical Dry Forests in Costa Rica

Forests ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 629
Author(s):  
Branko Hilje ◽  
Natalie V. Sánchez ◽  
Erin M. Bayne ◽  
Arturo Sánchez-Azofeifa
Keyword(s):  
Species Richness ◽  
Costa Rica ◽  
Structural Characteristics ◽  
Bird Species ◽  
Tropical Dry Forests ◽  
Forest Age ◽  
Age Classes ◽  
Dry Forests ◽  
Bird Species Richness ◽  
Different Ages

Research Highlights: While forest structure recovery in successional tropical forests is well studied, the recovery of fauna and changes in species composition and assemblage along forests succession is not well understood in many areas of the Neotropics like tropical dry forests (TDFs). Background and Objectives: To compare bird species richness and assemblage in tropical dry forests (TDFs) of different ages of recovery from cattle ranching and relate both to forest structural characteristics. Materials and Methods: To sample bird species richness and assemblage in 16 successional forest of different ages (i.e., 20, 30, 40, and 60 years old) using autonomous sound recording units in the TDFs in Costa Rica. Results: A total of 64 species of birds was detected across all forest age classes. The highest species richness was found in the 20-year-old class. Species richness decreased as canopy openness increased, suggesting low forest structural complexity and low availability of perches, nesting sites and food sources. However, bird assemblages were similar among the different forest age classes, suggesting that age itself was not a strong predictor, likely because of high variation in structure within age classes. Conclusions: TDFs can recover structural characteristics important to birds in only a few decades, supporting a rapid bird species assemblage recovery. However, this seems to depend on the starting conditions of the site prior to being recovered. Young TDFs, 20 years old, provide similar habitats for birds as 60-year-old forests do. These findings provide relevant information on the influence of TDF recovery after severe human impact on a highly threatened ecosystem.

Incontinence in aging leaves: deteriorating water relations with leaf age in Agastachys odorata (Proteaceae), a shrub with very long-lived leaves

2007 ◽  
Vol 34 (10) ◽  
pp. 918 ◽  
Author(s):  
Gregory J. Jordan ◽  
Timothy J. Brodribb
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Stomatal Density ◽  
Leaf Age ◽  
Carbon Assimilation ◽  
Leaf Damage ◽  
Evergreen Species ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency ◽  
Cuticle Thickness

This paper examines physiological characteristics of the leaves of Agastachys odorata R.Br., a wet-climate sclerophyllous shrub with very long-lived leaves. It addresses the hypothesis that cuticles become leakier to water vapour as leaves age. Astomatous cuticular conductance, whole-leaf minimum epidermal conductance, leaf damage and accumulation of epiphylls all increased several-fold with leaf age from first year growth to 10 years of age. Maximum carbon assimilation peaked 1 year after full leaf expansion, then declined. Intrinsic water use efficiency was highest in mid-aged leaves and declined markedly in the oldest leaves. Stomatal density, stomatal size and cuticle thickness did not vary significantly among ages. The older leaves were less effective at controlling water loss, resulting in decreases in water use efficiency. A differential increase in the conductance of the stomatal surface of the leaves relative to astomatous surface suggested that stomatal leakiness was significant in leaves over five years old. Although data for other species is ambiguous, the deterioration in A. odorata appears to be consistent with changes in the oldest leaves of other species. Thus, decreasing ability to use water efficiently appears to be a consequence of accumulated damage and may contribute to the need for leaf senescence in evergreen species with little self shading.

scholarly journals Growth Responses, Pigment and Stomatal Behaviour of Maize to Foliar Application of NAA

2017 ◽  
Vol 41 (1) ◽  
pp. 1-9
Author(s):  
Nargis Jahan ◽  
Nilufar Yasmin
Keyword(s):  
Plant Height ◽  
Stomatal Density ◽  
Dry Weight ◽  
Grain Filling ◽  
Naphthalene Acetic Acid ◽  
Growth Responses ◽  
Maximum Increase ◽  
Chl A ◽  
Stomatal Behaviour ◽  
Number Of Leaves

An investigation was conducted to find out the responses of two varieties of maize BHM- 7 (V1) and BHM-9 (V2) to Naphthalene acetic acid (NAA) on the growth, dry matter, pigment and stomatal behaviour. In case of V1, plant height was found to decrease due to all the treatments at all the ages except at 7 DAS due to T3 treatment. In V2, increase in plant height was recorded following T1 and T3 treatments at all the ages except at 21 DAS. In both the varieties at all the ages, maximum number of leaves per plant were obtained from T3 treatment. In case of V1 number of leaves per plant increased only due to T3 treatment in comparison to control whereas, in V2 number of leaves per plant increased following all the treatments. In case of V1, dry weight of shoot increased due to T3 treatment at 8 and 15 DAS. But in case of V2, there was increasing tendency in dry weight of shoot due to all treatments at all ages except at 8 DAS due to T2 treatment. In both the varieties dry weight of root increased due to T3 treatment at all ages. Chl. a was more than chl. b at all the stages in both the varieties and both chl. a and chl. b were recorded lowest at the flowering stage. In case of V1, amount of chl. b was remarkably higher at the tillering stage whereas, in case of V2, amount of chl. a and carotenoid were remarkably higher at the grain filling stage. In both the varieties, the amount of chl. a was found to increase and decrease due to all the treatments at all the stages. Chlorophyll b both increased and decreased in V1 and the maximum increase was due to T3 at the tillering and grain filling stages. In case of V2, chl. b increased at the tillering stage following all the treatments and maximum increase was also due to T3. However, in V1 carotenoid contents of leaf increased following all the treatments at the tillering stage and decreased following all the treatments at flowering and grain filling stages. Number of stomata increased except due to T2 in V1, whereas, number of epidermal cell decreased due to T0 and T2 in V1. Stomatal density in V2 was found relatively higher due to NAA application. It was also found that NAA increased the stomatal density with the increase of concentration except 50 ppm (T2) in V2. Stomatal index was found to decrease due to T1 inV1 and due to T0 in V2.Journal of Bangladesh Academy of Sciences, Vol. 41, No. 1, 1-9 2017

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