Germination of small-seeded tropical rain forest plants exposed to different spectral compositions

1996 ◽  
Vol 74 (4) ◽  
pp. 516-520 ◽  
Author(s):  
D. J. Metcalfe
Keyword(s):  
Rain Forest ◽  
Tropical Rain Forest ◽  
Shade Tolerance ◽  
Spectral Composition ◽  
Lower Percentage ◽  
Percentage Germination ◽  
Time Period ◽  
Deep Shade ◽  
Closed Canopy ◽  
Forest Plants

Seeds of 11 very small-seeded species with different degrees of shade tolerance as juveniles were tested for their response to neutral shade (6% daylight), green shade (3%), and darkness. Germination was monitored over 46 weeks. All species germinated in daylight to some extent. Species of Pternandra and Urophyllum, commonly found as juveniles in deep shade, germinated to the same percentage in green shade as in daylight, although over a longer time period, and to a lower percentage in the dark. Percentage germination of Gynotroches axillaris and Pellacalyx saccardianus, also found as juveniles in deep shade, was similar in all treatments, but much faster in daylight. Species of Ficus, which are found commonly as seedlings in deep shade but require higher irradiance for onward growth, germinated rapidly in daylight, and to a lower percentage and after a longer time in green shade than in the dark. Melastoma, which establishes in large gaps, germinated only in daylight. As most species can germinate under a spectral composition similar to canopy shade it is likely that they can germinate under a closed canopy in nature and may become established without the formation of even a transient canopy gap provided leaf litter is absent. Keywords: germination, red/far-red ratio, shade tolerance, tropical rain forest.

Butterfly behavioural responses to natural Bornean tropical rain-forest canopy gaps

2011 ◽  
Vol 28 (1) ◽  
pp. 45-54 ◽  
Author(s):  
James S. Pryke ◽  
Sven M. Vrdoljak ◽  
Paul B. C. Grant ◽  
Michael J. Samways
Keyword(s):  
Rain Forest ◽  
Tropical Rain Forest ◽  
Forest Canopy ◽  
Canopy Gaps ◽  
Tree Canopy ◽  
Canopy Openness ◽  
Butterfly Species ◽  
Behavioural Responses ◽  
Light Heterogeneity ◽  
Closed Canopy

Abstract:Natural tree canopy gaps allow sunlight to penetrate to the forest floor, a major environmental component and resource for many tropical rain-forest species. We compare here how butterflies use sunny areas created by the natural gaps in canopies in comparison with adjacent closed-canopy areas. We chose butterflies as our focal organisms as they are taxonomically tractable and mobile, yet habitat sensitive. Previous studies have shown that butterfly diversity in tropical forests responds to varying degrees of canopy openness. Here we assess butterfly behavioural responses to gaps and equivalent sized closed-canopy patches. Butterfly occupancy time and behaviour were simultaneously observed 61 times in gaps and 61 times in equivalent sized closed-canopy patches across four sites in a tropical rain forest in northern Borneo. Out of the 20 most frequently recorded species, 12 were more frequently recorded or spent more time in gaps, four occurred more frequently in closed-canopy areas, and four showed no significant differences. Overall agonistic, basking, patrolling and resting were more common in gaps compared with the closed canopy. Many butterfly species have complex behavioural requirements for both gaps and closed canopies, with some species using these different areas for different behaviours. Each butterfly species had particular habitat requirements, and needed both canopy gaps and closed canopy areas for ecological and behavioural reasons, emphasizing the need for natural light heterogeneity within these systems.

scholarly journals Acclimation of seedlings of three Mexican tropical rain forest tree species to a change in light availability

1991 ◽  
Vol 7 (1) ◽  
pp. 85-97 ◽  
Author(s):  
J. Popma ◽  
F. Bongers
Keyword(s):  
Growth Rates ◽  
Rain Forest ◽  
Tropical Rain Forest ◽  
Light Availability ◽  
Forest Tree ◽  
Gap Dynamics ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Closed Canopy ◽  
Acclimation Potential

ABSTRACTA comparison is made of the light acclimation potential of seedlings of three canopy species of the tropical rain forest of Los Tuxtlas, Mexico: Cordia megalantha, Lonchocarpus guatemalensis, and Omphalea oleifera. These species showed similar growth rates in a range of microhabitats. Gap dynamics were simulated by transferring plants between three environments: beneath a closed canopy, a small gap, and a large gap. Plants of all three species were able to adjust their morphology and growth rates in response to changes in light availability. Growth rates increased when plants were moved to a (larger) gap, and decreased when plants were moved to a more shaded environment. Shade-grown plants were able to acclimate faster to increasing light availability than sun-grown plants to decreasing light availability. Also, plants moved from shady to sunny conditions showed higher relative growth rates than sun control plants, whereas sun-grown plants when moved to the shade showed lower relative growth rates than shade control plants. Species differed in their response to gap dynamics. Omphalea could not acclimate morphologically to shading, but reacted faster than the other species in response to the occurrence of a large gap. Acclimation potential seemed to be related to plasticity in physiological rather than in morphological traits. Suppressed seedlings of all three species performed well in the shade, and were able to acclimate rapidly to gap-conditions.

Change in leaf structure in relation to crown position and size class for tree species within a Sri Lankan tropical rain forest

Botany ◽  
2008 ◽  
Vol 86 (6) ◽  
pp. 633-640 ◽  
Author(s):  
P. A.K.A.K. Panditharathna ◽  
B. M.P. Singhakumara ◽  
H. P. Griscom ◽  
M. S. Ashton
Keyword(s):  
Tree Species ◽  
Rain Forest ◽  
Tropical Rain Forest ◽  
Size Class ◽  
Leaf Structure ◽  
Sri Lankan ◽  
Size Classes ◽  
Canopy Trees ◽  
Crown Position ◽  
Closed Canopy

The purpose of our study was to examine change in leaf structure (anatomy and morphology) through different phases of tree size and crown position within a Sri Lankan rain forest. We selected four late-successional canopy species that represented dominant genera ( Shorea , Mesua ) within an Asian tropical rain forest. All are considered shade-tolerant and capable of growing to maturity beneath closed-canopy late-successional forests. Species within each genus were either restricted to seepages and bottom slopes (valley species) or to upper slopes and ridges (ridge species). The size classes represented (i) seedlings, (ii) saplings, (iii) poles growing beneath closed-canopy conditions, and (iv) trees of the rain forest canopy. Between size classes, leaves were thicker and with higher stomatal densities for canopy trees than for seedling, sapling, and pole size classes. Plasticities for measures of leaf structure were greater for ridge species than valley species; except for cuticle thickness, which showed the opposite trend (valley > ridge). Area, length, and width of leaves attained maxima for the sapling size class for all species. Drip-tip lengths were greatest for seedlings of all species, and least for canopy trees. Trends in leaf structure and morphology dimensions across size classes for late-successional canopy tree species are the same as those trends reported between rain forest species of different habitat strata (e.g., understory shrubs versus upper canopy trees). Our results suggest leaf dimensions could provide robust measures of environment, irrespective of species, or size class of tree.

scholarly journals Shade tolerance within the context of the successional process in tropical rain forests

2019 ◽  
Vol 67 (2SUPL) ◽  
pp. S53-S77 ◽  
Author(s):  
Gerardo Avalos
Keyword(s):  
Life Cycle ◽  
Rain Forest ◽  
Tropical Rain Forest ◽  
Shade Tolerance ◽  
Environmental Gradient ◽  
Forest Succession ◽  
Tropical Rain Forests ◽  
Rain Forests ◽  
Adult Trees ◽  
Successional Trajectory

Shade tolerance (the capacity to survive and grow over long periods under shade) is a key component of plant fitness and the foundation of current theories of forest succession in tropical rain forests. It serves as a paradigm to understand the optimal allocation of limited resources under dynamic light regimes. I analyze how tropical rain forest succession influences the expression of ecophysiological mechanisms leading to shade tolerance, and identify future areas that will increase our understanding of the ecological and evolutionary consequences of this phenomenon. Shade tolerance is a multivariate, continuous functional trait reflecting the growth-mortality trade-off of investing resources under limited light vs. exploiting high light conditions. I propose the life cycle successional trajectory model of Gómez-Pompa & Vázquez-Yanes as an integrative tool to understand tropical rain forest succession. This model shows how species distribute along the successional environmental gradient based on their degree of shade tolerance and represents a more integrative paradigm to understand the interface between different aspects of species diversity (ontogenetic variation and functional diversity) throughout succession. It proposes that different trait combinations determining shade tolerance are expressed at different stages of the life cycle, which affects how and when plants enter the successional trajectory. Models explaining the expression of shade tolerance (resource availability, carbon gain, CSR, resource competition) are based on whole-plant economics and are not mutually exclusive. The analysis of shade tolerance is biased towards tree seedlings in the understory of mature forests. Other life stages (juvenile and adult trees), life forms, and microhabitats throughout the forest profile are almost always excluded from these analyses. More integrative explanations based on the distribution of functional traits among species, ontogenetic stages, and the nature of the environmental gradient are being developed based on long-term data and chronosequence comparisons. In summary, shade-tolerance is a complex phenomenon, is determined by multiple characters that change ontogenetically over space and time and entails considerable plasticity. Current methods do not account for this plasticity. Understanding the nature of shade tolerance and its functional basis is critical to comprehending plant performance and improving the management, restoration and conservation of tropical rain forests given the combined threats of global warming and habitat loss

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