Trenching increased growth, and irrigation increased survival of tree seedlings in the understorey of a semi-evergreen rain forest in Panama

2007 ◽  
Vol 23 (3) ◽  
pp. 257-268 ◽  
Author(s):  
Edmund V. J. Tanner ◽  
Ignacio M. Barberis
Keyword(s):  
Tropical Forests ◽  
Rain Forest ◽  
Common Species ◽  
Nutrient Supply ◽  
Tree Seedlings ◽  
Tropical Rain Forests ◽  
Seedling Mortality ◽  
Canopy Trees ◽  
Below Ground ◽  
Dry Seasons

Seedlings in tropical forests are ultimately the source of canopy trees, thus factors controlling their composition and growth potentially influence the composition of the forest. Seedlings are primarily limited by above-ground competition with trees, but below-ground competition is potentially also important. Over 4 y we experimentally reduced below-ground competition by trenching to 50 cm and reduced drought stress by irrigating in the dry seasons (6 cm every 2 d) in the understorey of a semi-evergreen rain forest in Panama. There were four irrigated plots and four unirrigated, in each plot there were eight subplots (four trenched, four untrenched); 32 seedlings (two per subplot) of each of four tree species were equally allocated to the four treaments; the four species were: Aspidosperma cruenta; Gustavia superba; Simarouba amara and Tachigali versicolor. Over all species together, trenching increased seedling height by 41% and leaf area by 140% over 4 y. The cause was likely to be increased nutrient supply, because the amounts of N, K and Ca were higher in trenched plants, though concentrations were not higher. Irrigation had no significant effect on growth. Irrigation, but not trenching, reduced seedling mortality. We conclude that below-ground competition was a major limitation for seedling growth for at least some common species (Gustavia and Tachigali in this experiment). More experiments are necessary to determine whether below-ground competition is also important in other tropical rain forests on fairly fertile soils.

Juvenile tree growth in relation to light availability in second-growth tropical rain forests

2006 ◽  
Vol 22 (2) ◽  
pp. 223-226 ◽  
Author(s):  
Mary Beth Palomaki ◽  
Robin L. Chazdon ◽  
J. Pablo Arroyo ◽  
Susan G. Letcher
Keyword(s):  
Tropical Forests ◽  
Light Availability ◽  
Tree Seedlings ◽  
Tropical Rain Forests ◽  
Annual Increment ◽  
Growth And Survival ◽  
Second Growth ◽  
Direct Measurements ◽  
Crown Shape ◽  
Made In

Light is a key environmental factor limiting growth and survival of trees in the subcanopy of wet tropical forests (Davies 2001, Thomas 1996). Light availability varies both vertically and horizontally and affects tree height, crown shape and tree architecture (Bongers & Sterck 1998, Sterck & Bongers 2001, Sterck et al. 1999) in addition to growth and survival (Clark & Clark 1992, 2001). Although many studies of tree seedlings and saplings have shown that growth varies significantly with light availability in tropical wet forests (Clark et al. 1993, Iriarte & Chazdon 2005, King 1991, Kohyama 1991, Montgomery & Chazdon 2002, Oberbauer et al. 1988, 1993; Poorter & Werger 1999, Sterck et al. 1999, Welden et al. 1991), few studies have examined these relationships in size classes above 5 cm dbh (Sterck 1999). King et al. (2005) found that annual increment growth of trees in the 8–20-cm dbh size class in two Asian forests was positively dependent on an index of crown light interception, but no direct measurements of light availability were taken in this study. Due to logistical challenges, few direct measurements of light environments above tree crowns have been made in tropical forests (Sterck & Bongers 2001). To our knowledge, no measurements have been made in second-growth forests.

Profiles of CO2 concentration and δ13C values in tropical rain forests of the upper Rio Negro Basin, Venezuela

1986 ◽  
Vol 2 (3) ◽  
pp. 207-217 ◽  
Author(s):  
Ernesto Medina ◽  
Gustavo Montes ◽  
Elvira Cuevas ◽  
Zarko Rokzandic
Keyword(s):  
Organic Matter ◽  
Soil Surface ◽  
Co2 Concentration ◽  
Plant Tissues ◽  
Tree Seedlings ◽  
Tropical Rain Forests ◽  
Physiological Factors ◽  
Canopy Trees ◽  
Rio Negro ◽  
Rio Negro Basin

ABSTRACTConcentration of CO2, above and below the soil surface and δ13C values of plant tissues, soil litter and organic matter were measured in a caatinga forest of the upper Rio Negro basin in southern Venezuela. CO2, concentrations near the forest floor were consistently higher than in the atmosphere. CO2, gradient in the soil was very steep probably because of the poor aeration in this flood-prone forest. δ13C values of plant tissues showed a clear pattern with lower values in the ground herbaceous plants and under-canopy trees. Tree seedlings showed δ13C values similar to the upper-canopy trees indicating their dependence on reserves carried in the seed from the mother tree. Decomposing litter and soil organic matter also showed δ13C values similar to the upper-canopy trees. It is suggested that lower δ13C values of the shade flora result primarily from the assimilation of CO2, depleted in δ13C originating from soil respiration. Probable effects of low light intensity and physiological factors are discussed.

scholarly journals Do fungal pathogens drive density-dependent mortality in established seedlings of two dominant African rain-forest trees?

2010 ◽  
Vol 26 (3) ◽  
pp. 293-301 ◽  
Author(s):  
Julian M. Norghauer ◽  
David M. Newbery ◽  
Leho Tedersoo ◽  
George B. Chuyong
Keyword(s):  
Rain Forest ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Ecological Factors ◽  
Recruitment Rate ◽  
Tree Seedlings ◽  
Seedling Mortality ◽  
Density Dependent ◽  
Density Dependent Mortality ◽  
Dependent Mortality

Abstract:Where one or a few tree species reach local high abundance, different ecological factors may variously facilitate or hinder their regeneration. Plant pathogens are thought to be one of those possible agents which drive intraspecific density-dependent mortality of tree seedlings in tropical forests. Experimental evidence for this is scarce, however. In an African rain forest at Korup, we manipulated the density of recently established seedlings (~5–8 wk old; low vs. high-density) of two dominant species of contrasting recruitment potential, and altered their exposure to pathogens using a broad-spectrum fungicide. Seedling mortality of the abundantly recruiting subcanopy tree Oubanguia alata was strongly density-dependent after 7 mo, yet fungicide-treated seedlings had slightly higher mortality than controls. By contrast, seedling mortality of the poorly recruiting large canopy-emergent tree Microberlinia bisulcata was unaffected by density or fungicide. Ectomycorrhizal colonization of M. bisulcata was not affected by density or fungicide either. For O. alata, adverse effects of fungicide on its vesicular arbuscular mycorrhizas may have offset any possible benefit of pathogen removal. We tentatively conclude that fungal pathogens are not a likely major cause of density dependence in O. alata, or of early post-establishment mortality in M. bisulcata. They do not explain the latter's currently very low recruitment rate at Korup.

Microhabitat specialization of tropical rain-forest canopy trees in the Sovi Basin, Viti Levu, Fiji Islands

2011 ◽  
Vol 27 (5) ◽  
pp. 491-501 ◽  
Author(s):  
Gunnar Keppel ◽  
Marika V. Tuiwawa ◽  
Alifereti Naikatini ◽  
Isaac A. Rounds
Keyword(s):  
Species Diversity ◽  
Tree Species ◽  
Rain Forest ◽  
Forest Canopy ◽  
Niche Differentiation ◽  
Forest Tree ◽  
Common Species ◽  
Habitat Specificity ◽  
Canopy Trees ◽  
Fiji Islands

Abstract:Island biotas often have lower species diversity and less intense competition has been hypothesized as a result. This should result in lower habitat specificity compared with mainland habitats due to larger realized niches. We investigate microhabitat associations of canopy trees with regard to differences in topography on an oceanic island (Viti Levu, Fiji) using twenty 10 × 60-m plots. We find high tree-species diversity (112 species with dbh ≥ 10 cm in a total of 1.08 ha) and high endemism (c. 60%), compared with other islands in Western Polynesia. Our sample plots aggregate into three distinct groups that are mostly defined by micro-topography: (1) ridges and steep slopes (well-drained sites), (2) moderate slopes and ridge flats (moderate drainage), and (3) flats (poor drainage). Associations with microhabitat are found for more than 50% of the 41 most common species but only one species is apparently restricted to a single habitat. These findings are similar to other rain forests and demonstrate considerable niche differentiation among island rain-forest tree species.

Ants accelerate litter decomposition in a Costa Rican lowland tropical rain forest

2012 ◽  
Vol 28 (5) ◽  
pp. 437-443 ◽  
Author(s):  
Terrence P. McGlynn ◽  
Evan K. Poirson
Keyword(s):  
Mass Loss ◽  
Leaf Litter ◽  
Litter Decomposition ◽  
Rain Forest ◽  
Costa Rican ◽  
Tropical Rain Forests ◽  
Rain Forests ◽  
Food Web Structure ◽  
Litter Bags ◽  
Lowland Rain Forest

Abstract:The decomposition of leaf litter is governed, in part, by litter invertebrates. In tropical rain forests, ants are dominant predators in the leaf litter and may alter litter decomposition through the action of a top-down control of food web structure. The role of ants in litter decomposition was investigated in a Costa Rican lowland rain forest with two experiments. In a mesocosm experiment, we manipulated ant presence in 50 ambient leaf-litter mesocosms. In a litterbag gradient experiment, Cecropia obtusifolia litter was used to measure decomposition rate constants across gradients in nutrients, ant density and richness, with 27 separate litterbag treatments for total arthropod exclusion or partial arthropod exclusion. After 2 mo, mass loss in mesocosms containing ants was 30.9%, significantly greater than the 23.5% mass loss in mesocosms without ants. In the litter bags with all arthropods excluded, decomposition was best accounted by the carbon: phosphorus content of soil (r2 = 0.41). In litter bags permitting smaller arthropods but excluding ants, decomposition was best explained by the local biomass of ants in the vicinity of the litter bags (r2 = 0.50). Once the microarthropod prey of ants are permitted to enter litterbags, the biomass of ants near the litterbags overtakes soil chemistry as the regulator of decomposition. In concert, these results support a working hypothesis that litter-dwelling ants are responsible for accelerating litter decomposition in lowland tropical rain forests.

scholarly journals Fire suppression and seed dispersal play critical roles in the establishment of tropical forest tree species in southeastern Africa

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tomohiro Fujita
Keyword(s):  
Seed Dispersal ◽  
Tree Species ◽  
Seedling Survival ◽  
Fire Suppression ◽  
Forest Tree ◽  
Tree Seedlings ◽  
Seedling Mortality ◽  
Forest Tree Species ◽  
Seed Deposition ◽  
Syzygium Guineense

AbstractThis study examined the mechanisms of facilitation and importance of seed dispersal during establishment of forest tree species in an Afrotropical woodland. Seedling survival of Syzygium guineense ssp. afromontanum was monitored for 2.5 years at four different microsites in savannah woodland in Malawi (southeastern Africa) under Ficus natalensis (a potential nurse plant), Brachystegia floribunda (a woodland tree), Uapaca kirkiana (a woodland tree), and at a treeless site. The number of naturally established forest tree seedlings in the woodland was also counted. Additionally, S. guineense ssp. afromontanum seed deposition was monitored at the four microsites. Insect damage (9% of the total cause of mortality) and trampling by ungulates (1%) had limited impact on seedling survival in this area. Fire (43%) was found to be the most important cause of seedling mortality and fire induced mortality was especially high under U. kirkiana (74%) and at treeless site (51%). The rate was comparatively low under F. natalensis (4%) and B. floribunda (23%), where fire is thought to be inhibited due to the lack of light-demanding C4 grasses. Consequently, seedling survival under F. natalensis and B. floribunda was higher compared with the other two microsites. The seedling survival rate was similar under F. natalensis (57%) and B. floribunda (59%). However, only a few S. guineense ssp. afromontanum seedlings naturally established under B. floribunda (25/285) whereas many seedlings established under F. natalensis (146/285). These findings indicate that the facilitative mechanism of fire suppression is not the only factor affecting establishment. The seed deposition investigation revealed that most of the seeds (85%) were deposited under F. natalensis. As such, these findings suggest that in addition to fire suppression, dispersal limitations also play a role in forest-savannah dynamics in this region, especially at the community level.

Explaining Leaf Herbivory Rates on Tree Seedlings in a Malaysian Rain Forest

Biotropica ◽  
2007 ◽  
Vol 39 (3) ◽  
pp. 416-421 ◽  
Author(s):  
Markus P. Eichhorn ◽  
K. C. Fagan ◽  
Stephen G. Compton ◽  
Daisy H. Dent ◽  
Sue E. Hartley
Keyword(s):  
Rain Forest ◽  
Tree Seedlings ◽  
Leaf Herbivory

Ecological processes maintaining differential tree species distributions in an Australian subtropical rain forest: implications for models of species coexistence

2000 ◽  
Vol 16 (3) ◽  
pp. 387-415 ◽  
Author(s):  
Igor Debski ◽  
David F. R. P. Burslem ◽  
David Lamb
Keyword(s):  
Species Composition ◽  
Tree Species ◽  
Rain Forest ◽  
Large Scale ◽  
Species Coexistence ◽  
Common Species ◽  
Size Class ◽  
Differential Mortality ◽  
Mixed Composition ◽  
Large Scale Disturbance

All stems ≥ 1 cm dbh were measured, tagged, mapped and identified on a 1-ha plot of rain forest at Gambubal State Forest, south-east Queensland, Australia. The spatial patterns and size class distributions of 11 common tree species on the plot were assessed to search for mechanisms determining their distribution and abundance. The forest was species-poor in comparison to many lowland tropical forests and the common species are therefore present at relatively high densities. Despite this, only limited evidence was found for the operation of density-dependent processes at Gambubal. Daphnandra micrantha saplings were clumped towards randomly spaced adults, indicating a shift of distribution over time caused by differential mortality of saplings in these adult associated clumps. Ordination of the species composition in 25-m × 25-m subplots revealed vegetation gradients at that scale, which corresponded to slope across the plot. Adult basal area was dominated by a few large individuals of Sloanea woollsii but the comparative size class distributions and replacement probabilities of the 11 common species suggest that the forest will undergo a transition to a more mixed composition if current conditions persist. The current cohort of large S. woollsii individuals probably established after a large-scale disturbance event and the forest has not attained an equilibrium species composition.

scholarly journals Locally rare species influence grassland ecosystem multifunctionality

2016 ◽  
Vol 371 (1694) ◽  
pp. 20150269 ◽  
Author(s):  
Santiago Soliveres ◽  
Peter Manning ◽  
Daniel Prati ◽  
Martin M. Gossner ◽  
Fabian Alt ◽  
...  
Keyword(s):  
Land Use ◽  
Rare Species ◽  
Common Species ◽  
Ecosystem Functions ◽  
Individual Species ◽  
Conservation Priorities ◽  
Below Ground ◽  
Species Specific ◽  
The Relationship ◽  
Ecosystem Multifunctionality

Species diversity promotes the delivery of multiple ecosystem functions (multifunctionality). However, the relative functional importance of rare and common species in driving the biodiversity–multifunctionality relationship remains unknown. We studied the relationship between the diversity of rare and common species (according to their local abundances and across nine different trophic groups), and multifunctionality indices derived from 14 ecosystem functions on 150 grasslands across a land-use intensity (LUI) gradient. The diversity of above- and below-ground rare species had opposite effects, with rare above-ground species being associated with high levels of multifunctionality, probably because their effects on different functions did not trade off against each other. Conversely, common species were only related to average, not high, levels of multifunctionality, and their functional effects declined with LUI. Apart from the community-level effects of diversity, we found significant positive associations between the abundance of individual species and multifunctionality in 6% of the species tested. Species-specific functional effects were best predicted by their response to LUI: species that declined in abundance with land use intensification were those associated with higher levels of multifunctionality. Our results highlight the importance of rare species for ecosystem multifunctionality and help guiding future conservation priorities.

Female courtship calls of the litter frog (Rana curtipes) in the tropical forests of Western Ghats, South India

2005 ◽  
Vol 26 (4) ◽  
pp. 431-435 ◽  
Author(s):  
Savitha Krishna ◽  
Sharath Krishna
Keyword(s):  
Tropical Forests ◽  
Western Ghats ◽  
South India ◽  
Forest Litter ◽  
Calling Behavior ◽  
Tropical Rain Forests ◽  
Low Volume ◽  
Gravid Females ◽  
Female Call ◽  
The Western Ghats

AbstractWe noticed an uncommon phenomenon of female vocalization in the forest litter frog, Rana curtipes during the breeding season. We digitally recorded the male and female vocalization of the litter frogs in the tropical rain forests of the Western Ghats of South India and analyzed the call characteristics. The female call varied from the male call by being single note in composition. In contrast, the male calls were composed of seven to eight notes and longer in duration. We observed that gravid females, occupying the same location every day, emitted low volume calls when numerous males were found calling at that time. Some females arrived asynchronously and called even in the absence of males possibly to declare their receptive condition. Calling females responded agonistically to receptive conspecifics of the same sex. In addition to declaring receptivity, this calling behavior may be a response to adjacent competing females when the males are few.

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