Tropical Emergent Tree Research Articles

Physiological and growth strategies of two Cariniana species in response to contrasting light availability

Cariniana legalis and C. estrellensis are tropical emergent trees of the Lecythidaceae family that occur naturally in different forest ecosystems and belong to different ecological groups. With the aim of providing information to better manage these two congeneric Cariniana species in secondary forest enrichment plantations, an experiment was conducted using potted plants for comparing the physiological and growth responses of young C. legalis and C. estrellensis plants under contrasting light radiation availabilities. Considering that these two congeneric species occur naturally in different forest ecosystems and belong to different ecological groups, we tested the hypothesis that young plants of C. legalis have more plastic responses of photosynthetic light response curves, anthocyanin content, growth and biomass allocation to contrasting light environments than C. estrellensis. Plants were grown for 105 days under three light conditions (26, 10 and 1 mol photons m−2 day-1), simulating the daily total photosynthetic photon flux density (PPFD) in large and small canopy gaps and in the forest understory, respectively. The photosynthetic responses to contrasting light availabilities were very similar for both species. Higher values for anthocyanin reflectance index (ARI), leaf mass per area (LMA), and changes in biomass allocation indicate that C. legalis has a greater capacity for acclimation to contrasting light environments than did C. estrellensis. In addition, a greater number of smaller leaves in C. legalis could be an advantage in the understory of forests subjected to constant changes in canopy openness through the opening and closing of small- and medium-sized canopy gaps. From a practical point of view, seedlings of C. estrellensis should be planted in more open forests with less dynamic changes in canopy gaps, and seedlings of C. legalis should be planted in forests with more fluctuations in the opening and closing of small and large canopy gaps.

Shadows of the edge effects for tropical emergent trees: the impact of lianas on the growth of Aspidosperma polyneuron

Forest edge impacts emergent trees growth by reducing the number of growth releases. This reduction seems to be related with lianas infestation found at the forest edge. Deforestation in tropical regions is raising fragmentation to alarming levels. Not only does it lead to losses of forest area, but also the abiotic and biotic changes on forest edge areas alter the development of the remaining trees. We aimed to assess the impacts of forest fragmentation on the growth of tropical emergent trees. We sampled the endangered species Aspidosperma polyneuron (Apocynaceae) at forest edge and interior in the highly fragmented Brazilian Atlantic Forest. We obtained increment cores of each tree along with data about tree and surrounding canopy heights, plus their current levels of liana infestation. We used tree-ring analyses to estimate age and growth rate of trees. Sampled trees and surrounding canopy were taller at the forest interior than at the edge, even though both sampled populations have similar ages. Overall, trees at forest interior show a lifetime growth pattern common to shade-tolerant species, with a peak of growth rate at 120 years. Indeed, all sampled trees exhibited this pattern before fragmentation. However, trees at forest edge presented constantly slow growth rates for all diameter classes after the fragmentation event. The strong presence of lianas at forest edge prevents trees from experiencing the expected growth releases throughout their lifetime, probably by keeping the leaves of A. polyneuron under shaded conditions. Therefore, the management of lianas at the forest edge is likely the most effective procedure to ensure the growth of emergent trees, guarantying their role on forests structure, carbon storage, and ecosystem functioning.

Erratum to: Dynamics of mineral nutrient storage for mast reproduction in the tropical emergent tree Dryobalanops aromatica

Limitations in resources are considered to be important in mass-fruiting trees, based on the speculation that they need to consume a large amount of stored resources in a very short period. To test this hypothesis, we studied the total reproductive costs per individual of the tree Dryobalanops aromatica (Dipterocarpaceae), and the dynamics of stored mineral nutrients, specifically nitrogen, phosphorus, and potassium; we then estimated the contribution of each of the stored resources to reproduction in a lowland dipterocarp forest in Sarawak, Malaysia. D. aromatica is an emergent and masting tree species, and it produced a large amount of mature fruit in a masting period running 2001–2002. The dynamics patterns were markedly different for each of the stored nutrients. The phosphorus concentration clearly decreased in the branch, stem and root during reproduction, but nitrogen fluctuated by only a small amount in any organ during this period. The potassium concentration fell in all organs during flowering, but even increased during fruit development. Stored phosphorus accounted for 67.7% of the total phosphorus requirements for reproduction, but nitrogen accounted for only 19.7%. Stored potassium did not appear to contribute anything, at least to fruit production. Our results suggest that D. aromatica supplies phosphorus needed for reproduction mainly from stored resources in the tree, unlike nitrogen or potassium. The accumulation of phosphorus could be the decisive factor in the occurrence and frequency of mast reproduction in the relatively poor soil conditions prevailing in the tropical rain forests of Southeast Asia.

Dynamics of mineral nutrient storage for mast reproduction in the tropical emergent tree Dryobalanops aromatica

AbstractLimitations in resources are considered to be important in mass‐fruiting trees, based on the speculation that they need to consume a large amount of stored resources in a very short period. To test this hypothesis, we studied the total reproductive costs per individual of the tree Dryobalanops aromatica (Dipterocarpaceae), and the dynamics of stored mineral nutrients, specifically nitrogen, phosphorus, and potassium; we then estimated the contribution of each of the stored resources to reproduction in a lowland dipterocarp forest in Sarawak, Malaysia. D. aromatica is an emergent and masting tree species, and it produced a large amount of mature fruit in a masting period running 2001–2002. The dynamics patterns were markedly different for each of the stored nutrients. The phosphorus concentration clearly decreased in the branch, stem and root during reproduction, but nitrogen fluctuated by only a small amount in any organ during this period. The potassium concentration fell in all organs during flowering, but even increased during fruit development. Stored phosphorus accounted for 67.7% of the total phosphorus requirements for reproduction, but nitrogen accounted for only 19.7%. Stored potassium did not appear to contribute anything, at least to fruit production. Our results suggest that D. aromatica supplies phosphorus needed for reproduction mainly from stored resources in the tree, unlike nitrogen or potassium. The accumulation of phosphorus could be the decisive factor in the occurrence and frequency of mast reproduction in the relatively poor soil conditions prevailing in the tropical rain forests of Southeast Asia.

Using hyperspectral satellite imagery for regional inventories: a test with tropical emergent trees in the Amazon Basin

Questions: Understanding distributions of tree species at landscape scales in tropical forests is a difficult task that could benefit from the recent development of satellite imaging spectroscopy. We tested an application of the EO-1 Hyperion satellite sensor to spectrally detect the location of five important tree taxa in the lowland humid tropical forests of southeastern Peru. Location: Peru, Departamento de Madre de Díos. Methods: We used linear discriminant analysis with a stepwise selection procedure to analyze two Hyperion datasets (July and December 2006) to choose the most informative narrow bands for classifying trees. Results: Optimal channels selected were different between the two seasons. Classification was 100% successful for the five taxa when using 25 narrow bands and pixels that represented >40% of tree crowns. We applied the discriminant functions developed separately for the two seasons to the entire study area, and found significantly nonrandom overlap in the anticipated distributions of the five taxa between seasons. Conclusions: Despite known issues, such as signal-to-noise ratio and spatial resolution, Hyperion imaging spectroscopy has potential for developing regional mapping of large-crowned tropical trees.

Resource allocation to reproductive organs during masting in the tropical emergent tree, Dipterocarpus tempehes

Some tree species exhibit large year-to-year variation in seed production, a phenomenon known as masting (Kelly 1994, Kelly & Sork 2002). Even in tropical rain forests, in which the climate is suitable for plant growth all year round with little seasonal variation (Whitmore 1998), there are many reports of masting (Appanah 1993, Hart 1995, Newbery et al. 1998, Newstrom et al. 1994, Wheelwright 1986). In particular, Dipterocarpaceae, the dominant family in lowland mixed dipterocarp forests in South-East Asia, undergo mast fruiting following mass-flowering with strong interspecific synchronization in aseasonal western Malesia (Appanah 1985, 1993; Ashton 1989, Ashton et al. 1988, Curran et al. 1999, Janzen 1974, Medway 1972, Sakai et al. 1999, Whitmore 1998, Wood 1956). In mixed-dipterocarp forests, dipterocarp species contribute more than 70% of the canopy biomass (Bruenig 1996, Curran & Leighton 2000). Masting of dipterocarp species is therefore likely to have a major impact on animal populations, and also on the nutrient cycle in such forest ecosystems by causing fluctuations in the availability of resources (Sakai 2002).

Variation in pollen dispersal between years with different pollination conditions in a tropical emergent tree.

We examined differences in pollen dispersal efficiency between 2 years in terms of both spatial dispersal range and genetic relatedness of pollen in a tropical emergent tree, Dipterocarpus tempehes. The species was pollinated by the giant honeybee (Apis dorsata) in a year of intensive community-level mass-flowering or general flowering (1996), but by several species of moths in a year of less-intensive general flowering (1998). We carried out paternity analysis based on six DNA microsatellite markers on a total of 277 mature trees forming four spatially distinct subpopulations in a 70 ha area, and 147 and 188 2-year-old seedlings originating from seeds produced in 1996 and 1998 (cohorts 96 and 98, respectively). Outcrossing rates (0.93 and 0.96 for cohorts 96 and 98, respectively) did not differ between years. Mean dispersal distances (222 and 192 m) were not significantly different between the 2 years but marginally more biased to long distance in 1996. The mean relatedness among cross-pollinated seedlings sharing the same mothers in cohort 96 was lower than that in cohort 98. This can be attributed to the two facts that the proportion of intersubpopulations pollen flow among cross-pollination events was marginally higher in cohort 96 (44%) than in cohort 98 (33%), and that mature trees within the same subpopulations are genetically more related to each other than those between different subpopulations. We conclude that D. tempehes maintained effective pollen dispersal in terms of outcrossing rate and pollen dispersal distance in spite of the large difference in foraging characteristics between two types of pollinators. In terms of pollen relatedness, however, a slight difference was suggested between years in the level of biparental inbreeding.

Developmental and physiological correlates of leaf size in Hyeronima alchorneoides (Euphorbiaceae)

The tropical emergent tree Hyeronima alchorneoides has large decreases in leaf size with tree age: 1200 cm(2) at 1 yr, 900 cm(2) at 3 yr, 200 cm(2) at 11 yr, and 80 cm(2) in old (>30 yr) individuals. We tracked leaf growth and physiological attributes on trees of three different ages (1, 3, and 11 yr) to determine the developmental basis and functional consequences of this variation. Leaves on young trees grew faster and sustained maximum rates of leaf expansion longer than leaves on older trees. Leaf mass per area (LMA) did not differ among age classes. Maximum photosynthetic rates reflected differences in leaf nitrogen concentration, in which leaves from the lower crown of younger trees outperformed those at a comparable crown position in older trees. One-year-old trees had the lowest stomatal conductance and the greatest instantaneous water use efficiency. Ontogenetic plasticity in mature leaf size, structure, and physiology may be a balance between the advantages conferred by rapid height growth when trees are young and the benefits derived from producing branches that increase light harvesting ability as trees reach the canopy.

Age and Long‐term Growth of Trees in an Old‐growth Tropical Rain Forest, Based on Analyses of Tree Rings and 14C1

ABSTRACTIn an old‐growth tropical wet forest at La Selva, Costa Rica, we combined radiocarbon (14C) dating and tree‐ring analysis to estimate the ages of large trees of canopy and emergent species spanning a broad range of wood densities and growth rates. We collected samples from the trunks of 29 fallen, dead individuals. We found that all eight sampled species formed visible growth rings, which varied considerably in distinctiveness. For five of the six species for which we combined wood anatomical studies with 14C‐dates (ring ages), the analyses demonstrated that growth rings were of annual formation. The oldest tree we found by direct ring counting was a Hymenolobium mesoamericanum Lima (Papilionaceae) specimen, with an age of ca. 530 years at the time of death. All other sampled individuals, including very large trees of slow‐growing species, had died at ages between 200 and 300 years. These results show that, even in an everwet tropical rain forest, tree growth of many species can be rhythmic, with an annual periodicity. This study thus raises the possibility of extending tree‐ring analyses throughout the tropical forest types lacking a strong dry season or annual flooding. Our findings and similar measurements from other tropical forests indicate that the maximum ages of tropical emergent trees are unlikely to be much greater than 600 years, and that these trees often die earlier from various natural causes.

Variability in pollination conditions, pollen dispersal patterns, and pollen relatedness: an example of a tropical emergent tree.

Recent understanding on biparental inbreeding depression teaches us that pollen relatedness to female gametes should be regarded as a significant aspect of pollen quality. Pollen relatedness is determined by pollen dispersal pattern and spatial genetic structure, however the former is possibly affected to varying degrees by certain variations in pollination conditions. Our recent study, which applied DNA microsatellite markers to study pollen dispersal patterns and pollen relatedness in a tropical emergent tree in two years, showed that the level of inbreeding differed affected by different types of pollinators. This infers that pollen of good quality dispersed under a particular pollination condition may play a significant role in population regeneration. Relationships between pollen dispersal patterns and various reproductive traits or conditions should be elucidated to better understand plant reproductive strategies.

Age and Long-term Growth of Trees in an Old-growth Tropical Rain Forest, Based on Analyses of Tree Rings and 14C1

In an old-growth tropical wet forest at La Selva, Costa Rica, we combined radiocarbon (14C) dating and tree-ring analysis to estimate the ages of large trees of canopy and emergent species spanning a broad range of wood densities and growth rates. We collected samples from the trunks of 29 fallen, dead individuals. We found that all eight sampled species formed visible growth rings, which varied considerably in distinctiveness. For five of the six species for which we combined wood anatomical studies with 14C-dates (ring ages), the analyses demonstrated that growth rings were of annual formation. The oldest tree we found by direct ring counting was a Hymenolobium mesoamericanum Lima (Papilionaceae) specimen, with an age of ca. 530 years at the time of death. All other sampled individuals, including very large trees of slow-growing species, had died at ages between 200 and 300 years. These results show that, even in an everwet tropical rain forest, tree growth of many species can be rhythmic, with an annual periodicity. This study thus raises the possibility of extending tree-ring analyses throughout the tropical forest types lacking a strong dry season or annual flooding. Our findings and similar measurements from other tropical forests indicate that the maximum ages of tropical emergent trees are unlikely to be much greater than 600 years, and that these trees often die earlier from various natural causes.

Microsatellite loci for a tropical emergent tree, Dipterocarpus tempehes V. Sl. (Dipterocarpaceae)

AbstractPolymerase chain reaction primers amplifying 10 microsatellite loci for a tropical emergent tree, Dipterocarpus tempehes (Dipterocarpaceae) were developed. The polymorphism was estimated by screening 34 adult trees. The numbers of alleles per locus were from seven to 14 with the average of 10.3. Expected heterozygosity ranged from 0.57 to 0.88 with the average of 0.78. Total exclusion probabilities with the present 10 loci for the first and second parents of seedlings were 0.9962 and 0.9999, respectively. The high level of polymorphism indicates that the present loci are useful for the analysis of pollen movement, seed dispersal and inbreeding depression.

Estimation of gene flow in the tropical-rainforest tree Neobalanocarpus heimii (Dipterocarpaceae), inferred from paternity analysis.

Pollen flow and population genetic structure among 30 potentially flowering individuals of Neobalanocarpus heimii, a tropical emergent tree, were investigated in a lowland tropical rainforest of Malaysia using microsatellite polymorphism. The 248 offspring in the vicinity of five reproductive trees of the 30 potentially flowering trees were used in paternity analysis for pollen-flow study. Four primer pairs, developed in different species of dipterocarps, were adopted to detect microsatellite polymorphism. Based upon microsatellite polymorphism, pollen flow and seed migration were detected. Pollen-flow events of more than 400 m were observed directly, based on paternity analysis in the study plot. The estimated average mating distance of the five reproductive trees was 524 m. This result suggests that reproduction of this species is mediated by a long-distance pollinator. The haplotypes of some offspring were not compatible with the nearest reproductive tree. Thus, the results suggest that some seeds are dispersed by a seed dispersal vector. Investigation of genetic structure showed significant and negative correlation of genetic relatedness and spatial distances between the 30 potentially flowering trees, but this correlation was weak. We suggest that long-distance gene flow and seed migration are responsible for the poorly developed genetic structure of this species.