Simarouba amara
Encyclopedia
Simarouba amara is a species of tree
in the Simaroubaceae
family, found in the rainforest
s and savannah
s of South
and Central America
and the Caribbean
. It was first described
by Aublet
in French Guiana
in 1775 and is one of six species of Simarouba
. The tree is evergreen
, but produces a new set of leaves once a year. It requires relatively high levels of light to grow and grows rapidly in these conditions, but lives for a relatively short time. In Panama, it flowers during the dry season
in February and March, whereas in Costa Rica, where there is no dry season it flowers later, between March and July. As the species is dioecious
, the trees are either male or female and only produce male or female flowers. The small yellow flowers are thought to be pollinated by insects, the resulting fruits are dispersed
by animals including monkeys, birds and fruit-eating bats and the seeds are also dispersed by leaf cutter ants.
Simarouba amara has been studied extensively by scientists in an attempt to understand the tree and also to gain a better understanding of the ecology
of the rainforest in general. Many of these studies were conducted on Barro Colorado Island
in Panama
or at La Selva Biological Station in Costa Rica
. Of particular interest is how it competes
with other species
and with individuals of the same species
at different stages in its life cycle
. The seedlings are normally limited by the amount of light and nutrients found where they are growing and the saplings are considered relatively light demanding compared to other species. Young individuals are more likely to survive when they grow further away from their parents and when there are few other individuals growing near to them, which may be due to them being able to escape diseases. Plant physiologists have investigated how the leaves of the tree differ depending on their location in the forest canopy finding they are thicker in the canopy and thinner in the understory. They have also measured how the water potential
of their leaves changes and when their stomata open and close during the day; the findings suggest that rather than closing their stomata to control water loss, it is controlled by the leaf area instead. Population geneticists
have examined the way in which its genes vary
, at both the local scale and across its range
using microsatellites. It is genetically diverse, indicating gene flow
occurs between populations and seeds can be dispersed up to 1 km. The leaves of S. amara are eaten by several species of caterpillar
, particularly those in the Atteva genus. Several species of termite
and ant
s live on or around the tree and liana
s and epiphyte
s grow on the tree.
The bark of S. amara has been used by people in its range to treat dysentery
and diarrhea
, as well as other diseases, and was also exported to Europe in the eighteenth century to treat these illnesses. A number of compounds have since been isolated from the bark and have been shown to have antimicrobial
effects. Local people use the wood of the tree for various purposes and it is also grown in plantation
s and harvested for its timber, some of which is exported.
s are 4–7 cm long and each leaf has 9–16 leaflets. Each leaflet is 2.5–11 cm long and 12–45 mm wide, with those towards the end of the compound leaf tending to be smaller. The flowers occur on a staminate panicle
that is around 30 cm in length, which is widely branched and densely covered in flowers.
The flowers are unisexual, small (<1 cm long) and pale yellow in colour. They are thought to be pollinated by insects such as small bee
s and moth
s. On Barro Colorado Island
(BCI), Panama, it tends to flower during the dry season
from the end of January to the end of April, persisting for 11 to 15 weeks each year. In Costa Rica, it flowers slightly later, between March and July, peaking in April. Fruits form between 1 and 3 months after pollination occurs. The fruits are brightly colored green to purplish-black, approximately 17 mm long and contain large seeds (10–14 mm), they occur in groups of 3–5 drupe
s. The seeds cannot stay dormant
and are dispersed
by vertebrates. Each seed weighs approximately 0.25 g.
It is an evergreen species, with a new flush of leaves growing between January and April, during the dry season, when the highest light levels occur in the rainforest. This phenology
is thought to allow S. amara to photosynthesise most effectively, since the new leaves are more efficient than those they replace. It has visible, but indistinct growth rings that are on average 7 mm wide. A study of individuals in Panama found that they grow on average 8.4 mm in diameter each year, in Costa Rica, growth rates as fast as 18 mm per year have been recorded, and the stem grows constantly throughout the year. The xylem
vessels in mature trees range from 20 to 90 μm in diameter, with around 50 vessels present per mm2 of branch. The density
of the wood is between 0.37–0.44 g/cm3, lower than many other species in the rainforest.
It is a fast-growing, light-demanding and shade-intolerant
species. Saplings are typically one straight pole, with several compound leaves and only one point of growth. This allows the sapling to achieve the greatest vertical growth with a minimum amount of biomass. They start to branch once they are 2–5 m tall.
A study in the forest dynamics
plot on BCI found that between 1982 and 2000, around 65% of individuals died, with mortality highest amongst small individuals (<1 cm dbh
). Large trees (>20 cm dbh) are relatively rare, averaging 2.4 trees per hectare, compared to 40 trees per hectare of >1 cm dbh.
in French Guiana
in 1775 and is the type species
of the Simarouba
genus. In 1790, William Wright
described Quassia simarouba, which Auguste Pyrame DeCandolle suggested was the same species as S. amara. However, because S. amara was described as monoecious by Aublet and Q. simarouba was described as dioecious by Wright, they were still regarded as separate species in 1829. By 1874, when the Flora Brasiliensis
was published, they were considered synonymous.
Among the six species of Simarouba, two besides S. amara occur on the continent: S. glauca
and S. versicolor. S. amara can be distinguished from the other continental species by having smaller flowers, anthers and fruit, and straight, rather than curved petals. The leaves of Simarouba amara subsp. opaca are not glaucous
(a bluish-grey or green colour) on their underside, whereas those of Simarouba amara subsp. typica are.
In Europe, it was known by various names during the nineteenth century when it was used as a medicine; these names included bitter ash, bitterwood, mountain damson and stave-wood.
of Central
and South America
. Its range extends from Guatemala
in the north, to Bolivia
in the south and from Ecuador
in the west, to the east coast of Brazil
. It has been introduced
to the islands of Dominica
and Puerto Rico
in the Caribbean Sea, becoming naturalised in Puerto Rico. On BCI, mature trees (>10 cm dbh) are found at a frequency of 5 per hectare, in Ecuador at 0.7 per hectare and in French Guiana at 0.4 per hectare. Genetic analysis of populations suggests that it has always been relatively common within its range. It grows in rainforests and in savannah
s. The seedlings of S. amara are rare in primary forest due to their light-demanding habit.
s of S. amara display high levels of heterozygosity indicating that it is genetically diverse
. This is consistent with the tree outcrossing over large distances by long-distance pollen flow and that there has been sufficient long distance gene flow
between populations to counteract the effects of genetic drift
. A study of 478 plants from 14 populations across South America found that 24% of all allele
s occurred in only one population. A study of 300 plants on Barro Colorado Island
found that the heterozygosity at 5 microsatellite loci varied between 0.12 and 0.75. 8 out of the 50 alleles scored occurred in only one plant.
s, but other authors have questioned whether this is correct.
The seeds of S. amara are dispersed
by vertebrates, mainly large birds and mammals, including chachalaca
s, flycatcher
s, motmot
s, thrush
es, howler monkey
s, tamarin
s and spider monkey
s. Leaf cutter ants have also been observed to disperse the seeds and dense seedling
carpets form in areas where they dump waste material. Seeds that are eaten by monkeys are more likely to germinate than seeds that have not. Fruit-eating phyllostomid bats have also been noted to disperse their seeds; this may aid the regeneration of forests as they disperse the seeds of later successional species while they feed on S. amara.
Based on inverse modelling of data from seed trap
s on BCI, the estimated average dispersal distance for seeds is 39 m. Studying seedlings and parent trees on BCI using DNA microsatellites revealed that, in fact on average, seedlings grow 392 m away from their parents, with a standard deviation
of ±234 m and a range of between 9 m and 1 km. In the forest there are many seeds and seedlings beneath reproductive females; genetic data indicate that seedlings are unlikely to be from nearby adults, but rather dispersed there by vertebrates that have fed on one tree and then moved to feed on another, defecating while in the canopy and depositing the seeds.
or S. amara have been studied. The stomatal conductance
of the leaves, an indication of the rate at which water evaporates
, of mature trees at midday range from 200 to 270 mmol H2O m−2 s−1. The leaf water potential
s at midday range from −0.56 to −1.85 MPa
, averaging around −1.2 MPa. Cavitation is widespread in the trunk and the stomata do not close before cavitation occurs. Although this would normally be considered deleterious to the tree, it may buffer the leaf water potential and therefore be beneficial. The stomatal conductance and hydraulic conductance of the branches of taller trees (~30 m) are much higher than in the branches of smaller trees (~20 m). Phillips, Bond and Ryan suggested that this is probably due to the branches of taller trees having a lower leaf-to-sapwood ratio than those of small branches. Dye staining shows that cavitation is common in the branches of S. amara. They concluded that water flux in S. amara is controlled by structural (leaf area), rather than physiological (closing stomata) means.
Leaves absorb light
in the photosynthetically active radiation
(PAR) spectrum
at wavelength
s between 400 nm and 700 nm with a high efficiency, but the efficiency decreases at longer wavelengths. Generally plants absorb PAR at efficiencies of around 85%; the higher values found in S. amara are thought to be due to the high humidity
of its habitat. The reflectance and transmittance
of the leaves are low at between 400 and 700 nm. The optical properties and the mass of the leaves vary depending on their location in the forest canopy, with leaves becoming thicker and more efficient as their height within the canopy increases. For their weight, however, leaves in the understory are more efficient at capturing light than leaves in the canopy.
The concentration of bioavailable phosphate
has been found to be higher underneath female individuals than underneath males, even though the total concentration of phosphate is equal. Rhoades et al. concluded that this difference was due to females changing the availability of phosphate, rather than females only growing in areas with high phosphate availability. This is thought to be caused either by the fruit containing high levels of phosphate which would fall off the tree and rot, or by the fruits attracting animals which deposit phosphate beneath the females. It is also possible that the sexes produce different root exudates, which affect the microbial community in their rhizosphere
, thereby affecting phosphate availability.
The woody tissues of S. amara have been found to respire
at a rate of 1.24 μmol m−2 s−1, and this rate of respiration correlates positively with the growth rate of the stem. Maintenance respiration
was calculated at 31.1 μmol m−3 s−1 and this rate correlated positively with the sapwood volume.
Experiments on BCI where trenches were dug around seedlings of S. amara, or where gaps in the canopy where made above them, show that their relative growth rate
can be increased by both. This shows that their growth is normally limited by both above-ground competition
for light and by below-ground competition for nutrients
and water. Competition for light is normally more important, as shown by the growth rate increasing by almost 7 times and mortality decreasing, when seedlings were placed in gaps, compared to the understory. When seedlings in gaps had a trench dug round them to prevent below-ground competition their growth increased further, by 50%, demonstrating that in gaps the seedlings are limited by below-ground competition. Trenching around seedlings in the understory did not significantly increase their growth, showing that they are normally only limited by competition for light.
Larger seedlings are more likely to survive the dry season on BCI than smaller seedlings. Density-dependent inhibition occurs between seedlings: they are more likely to survive in areas where fewer seedlings of S. amara are growing. A study on individuals on BCI found that this pattern may be caused by differences in soil biota rather than by insect herbivores or fungal pathogens. Observations based on the distance of seedlings from their parents indicate that the Janzen-Connell hypothesis
applies to seedlings of S. amara: they are more likely to survive away from their parents as they escape pests such as herbivore
s and plant pathogens which are more common underneath the parent trees.
of the leaves of S. amara is higher than that of the other two species, averaging around 6 μmol m−1 s−1. Dark respiration
is on average 0.72 μmol m−1 s−1, higher than that of the other two species. The maximum photosynthetic rate correlates with both stem diameter and vertical growth. Diffuse light is thought to be more important for seedling growth than sunfleck
s. Another study of saplings at La Selva found that they grew 7 cm yr−1 in height and 0.25 mm yr−1 in diameter. On average they had nine compound leaves, a leaf area index
of 0.54 and the total surface area of their leaves was 124 cm2. The saplings that had the lowest leaf area were most likely to die during the study and those with a larger leaf area grew faster than other saplings.
A study of saplings between one and four centimeters in diameter on BCI found that the growth of saplings did not vary depending on which species grew near them, contrary to predictions that density-dependence inhibition occurs. A model based on these findings predicted that saplings with a diameter of 2 cm are able to grow at a maximum rate of 13 mm yr−1 and that if another tree with a diameter of 10 cm is growing within 5 m of the sapling, its growth is only reduced to 12 mm yr−1, indicating that they are not affected by crowding. Trees growing more than 15 m away from a sapling do not affect their growth.
s than other species of tree in the same forests.
The alianthus webworm (Atteva aurea) and other members of the Atteva genus have been recorded to eat the new shoot tips of S. amara in Costa Rica. The larvae of the butterfly species, Bungalotis diophorus feed exclusively on saplings and treelets of S. amara. Two termite
species have been observed living on S. amara in Panama, Calcaritermes brevicollis in dead wood and Microcerotermes arboreus nesting in a gallery on a branch. Bullet ants (Paraponera clavata) have been found to nest at the base of S. amara trees. The Hemiptera
, Enchophora sanguinea
(Fulgoridae) has been found preferentially on the trunks of S. amara.
s. The wood dries rapidly and is easy to work with normal tools. It is creamy white to light yellow in colour, with a coarse texture and a straight grain. It has to be treated
to prevent fungi, wood borers and termite
s from eating it. The heartwood has a density of 0.35–0.45 g/cm3. It has been noted to be one of the best species for timber that can be grown in the Peruvian Amazon
, along with Cedrelinga catenaeformis, due to its rapid growth characteristics. The Worldwide Fund for Nature recommend that consumers ensure S. amara timber is certified by the Forest Stewardship Council
so that they do not contribute to deforestation
. Wood shavings of S. amara have been used in animal bedding leading to the poisoning of horses and dogs.
, diarrhea
, malaria
and other illnesses in traditional medicine
in areas where it grows. In 1713, it was exported to France where it was used to treat dysentery, being an effective treatment during epidemics between 1718 and 1725. In 1918 its effectiveness was validated by a study where soldiers in a military hospital were given a tea made of the bark to treat amoebic dysentery
. In a 1944 study, the Merck Institute found it was 92% effective at treating intestinal amoebiasis in humans. During the 1990s, scientists demonstrated it could kill the most common cause of dysentery, Entamoeba histolytica
, and species of Salmonella
and Shigella
bacteria that cause diarrhea. The main biologically active compounds found in S. amara are the quassinoids, a group of triterpene
s, of which the most therapeutic are ailanthinone, glaucarubinone, and holacanthone. These have been reported to kill protozoa, amoeba, Plasmodium
(the cause of malaria) and also cancerous human cells. The anti-malarial properties were first investigated by scientists in 1947; they found that in chickens, 1 mg of bark extract per 1 kg of body weight had strong antimalarial activity. In 1997 a patent was filed in the United States for using an extract in a skin care product.
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
in the Simaroubaceae
Simaroubaceae
The Simaroubaceae is a small, mostly tropical, family in the order Sapindales. In recent decades it has been subject to much taxonomic debate, with several small families being split off...
family, found in the rainforest
Rainforest
Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...
s and savannah
Savannah
Savannah or savanna is a type of grassland.It can also mean:-People:* Savannah King, a Canadian freestyle swimmer* Savannah Outen, a singer who gained popularity on You Tube...
s of South
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
and Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
and the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
. It was first described
Species description
A species description or type description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species which have been described previously, or are...
by Aublet
Jean Baptiste Christophore Fusée Aublet
Jean Baptiste Christophore Fusée Aublet was a French pharmacist, botanist and explorer.Born in Salon-de-Provence, he joined the French East India Company and in 1752 was sent to Mauritius to establish a pharmacy and a botanical garden. He worked there for nine years...
in French Guiana
French Guiana
French Guiana is an overseas region of France, consisting of a single overseas department located on the northern Atlantic coast of South America. It has borders with two nations, Brazil to the east and south, and Suriname to the west...
in 1775 and is one of six species of Simarouba
Simarouba
Simarouba is a genus of trees and shrubs in the Simaroubaceae family, native to the neotropics. It has been grouped in the subtribe Simaroubina along with the Simaba and Quassia genera. They have compound leaves, with between 1 and 12 pairs of alternate pinnate leaflets. Their flowers are...
. The tree is evergreen
Evergreen
In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...
, but produces a new set of leaves once a year. It requires relatively high levels of light to grow and grows rapidly in these conditions, but lives for a relatively short time. In Panama, it flowers during the dry season
Dry season
The dry season is a term commonly used when describing the weather in the tropics. The weather in the tropics is dominated by the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year...
in February and March, whereas in Costa Rica, where there is no dry season it flowers later, between March and July. As the species is dioecious
Dioecious
Dioecy is the property of a group of biological organisms that have males and females, but not members that have organs of both sexes at the same time. I.e., those whose individual members can usually produce only one type of gamete; each individual organism is thus distinctly female or male...
, the trees are either male or female and only produce male or female flowers. The small yellow flowers are thought to be pollinated by insects, the resulting fruits are dispersed
Seed dispersal
Seed dispersal is the movement or transport of seeds away from the parent plant. Plants have limited mobility and consequently rely upon a variety of dispersal vectors to transport their propagules, including both abiotic and biotic vectors. Seeds can be dispersed away from the parent plant...
by animals including monkeys, birds and fruit-eating bats and the seeds are also dispersed by leaf cutter ants.
Simarouba amara has been studied extensively by scientists in an attempt to understand the tree and also to gain a better understanding of the ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
of the rainforest in general. Many of these studies were conducted on Barro Colorado Island
Barro Colorado Island
Barro Colorado Island is located in the man-made Gatun Lake in the middle of the Panama Canal. The island was formed when the waters of the Chagres River were dammed to form the lake. When the waters rose, they covered a significant part of the existing rainforest, and the hilltops remained as...
in Panama
Panama
Panama , officially the Republic of Panama , is the southernmost country of Central America. Situated on the isthmus connecting North and South America, it is bordered by Costa Rica to the northwest, Colombia to the southeast, the Caribbean Sea to the north and the Pacific Ocean to the south. The...
or at La Selva Biological Station in Costa Rica
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....
. Of particular interest is how it competes
Competition (biology)
Competition is an interaction between organisms or species, in which the fitness of one is lowered by the presence of another. Limited supply of at least one resource used by both is required. Competition both within and between species is an important topic in ecology, especially community ecology...
with other species
Interspecific competition
Interspecific competition, in ecology, is a form of competition in which individuals of different species compete for the same resource in an ecosystem...
and with individuals of the same species
Intraspecific competition
Intraspecific competition is a particular form of competition in which members of the same species vie for the same resource in an ecosystem...
at different stages in its life cycle
Biological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...
. The seedlings are normally limited by the amount of light and nutrients found where they are growing and the saplings are considered relatively light demanding compared to other species. Young individuals are more likely to survive when they grow further away from their parents and when there are few other individuals growing near to them, which may be due to them being able to escape diseases. Plant physiologists have investigated how the leaves of the tree differ depending on their location in the forest canopy finding they are thicker in the canopy and thinner in the understory. They have also measured how the water potential
Water potential
Water potential is the potential energy of water per unit volume relative to pure water in reference conditions. Water potential quantifies the tendency of water to move from one area to another due to osmosis, gravity, mechanical pressure, or matrix effects such as surface tension...
of their leaves changes and when their stomata open and close during the day; the findings suggest that rather than closing their stomata to control water loss, it is controlled by the leaf area instead. Population geneticists
Population genetics
Population genetics is the study of allele frequency distribution and change under the influence of the four main evolutionary processes: natural selection, genetic drift, mutation and gene flow. It also takes into account the factors of recombination, population subdivision and population...
have examined the way in which its genes vary
Genetic variation
Genetic variation, variation in alleles of genes, occurs both within and among populations. Genetic variation is important because it provides the “raw material” for natural selection. Genetic variation is brought about by mutation, a change in a chemical structure of a gene. Polyploidy is an...
, at both the local scale and across its range
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...
using microsatellites. It is genetically diverse, indicating gene flow
Gene flow
In population genetics, gene flow is the transfer of alleles of genes from one population to another.Migration into or out of a population may be responsible for a marked change in allele frequencies...
occurs between populations and seeds can be dispersed up to 1 km. The leaves of S. amara are eaten by several species of caterpillar
Caterpillar
Caterpillars are the larval form of members of the order Lepidoptera . They are mostly herbivorous in food habit, although some species are insectivorous. Caterpillars are voracious feeders and many of them are considered to be pests in agriculture...
, particularly those in the Atteva genus. Several species of termite
Termite
Termites are a group of eusocial insects that, until recently, were classified at the taxonomic rank of order Isoptera , but are now accepted as the epifamily Termitoidae, of the cockroach order Blattodea...
and ant
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...
s live on or around the tree and liana
Liana
A liana is any of various long-stemmed, woody vines that are rooted in the soil at ground level and use trees, as well as other means of vertical support, to climb up to the canopy to get access to well-lit areas of the forest. Lianas are especially characteristic of tropical moist deciduous...
s and epiphyte
Epiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...
s grow on the tree.
The bark of S. amara has been used by people in its range to treat dysentery
Dysentery
Dysentery is an inflammatory disorder of the intestine, especially of the colon, that results in severe diarrhea containing mucus and/or blood in the faeces with fever and abdominal pain. If left untreated, dysentery can be fatal.There are differences between dysentery and normal bloody diarrhoea...
and diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
, as well as other diseases, and was also exported to Europe in the eighteenth century to treat these illnesses. A number of compounds have since been isolated from the bark and have been shown to have antimicrobial
Antimicrobial
An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...
effects. Local people use the wood of the tree for various purposes and it is also grown in plantation
Plantation
A plantation is a long artificially established forest, farm or estate, where crops are grown for sale, often in distant markets rather than for local on-site consumption...
s and harvested for its timber, some of which is exported.
Description
Simarouba amara grows to heights of up to 35 metres, with a maximum trunk diameter of 125 cm and a maximum estimated age of 121 years. It has compound leaves that are each around 60 cm long, the petiolePetiole (botany)
In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...
s are 4–7 cm long and each leaf has 9–16 leaflets. Each leaflet is 2.5–11 cm long and 12–45 mm wide, with those towards the end of the compound leaf tending to be smaller. The flowers occur on a staminate panicle
Panicle
A panicle is a compound raceme, a loose, much-branched indeterminate inflorescence with pedicellate flowers attached along the secondary branches; in other words, a branched cluster of flowers in which the branches are racemes....
that is around 30 cm in length, which is widely branched and densely covered in flowers.
The flowers are unisexual, small (<1 cm long) and pale yellow in colour. They are thought to be pollinated by insects such as small bee
Bee
Bees are flying insects closely related to wasps and ants, and are known for their role in pollination and for producing honey and beeswax. Bees are a monophyletic lineage within the superfamily Apoidea, presently classified by the unranked taxon name Anthophila...
s and moth
Moth
A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...
s. On Barro Colorado Island
Barro Colorado Island
Barro Colorado Island is located in the man-made Gatun Lake in the middle of the Panama Canal. The island was formed when the waters of the Chagres River were dammed to form the lake. When the waters rose, they covered a significant part of the existing rainforest, and the hilltops remained as...
(BCI), Panama, it tends to flower during the dry season
Dry season
The dry season is a term commonly used when describing the weather in the tropics. The weather in the tropics is dominated by the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year...
from the end of January to the end of April, persisting for 11 to 15 weeks each year. In Costa Rica, it flowers slightly later, between March and July, peaking in April. Fruits form between 1 and 3 months after pollination occurs. The fruits are brightly colored green to purplish-black, approximately 17 mm long and contain large seeds (10–14 mm), they occur in groups of 3–5 drupe
Drupe
In botany, a drupe is a fruit in which an outer fleshy part surrounds a shell of hardened endocarp with a seed inside. These fruits develop from a single carpel, and mostly from flowers with superior ovaries...
s. The seeds cannot stay dormant
Seed dormancy
Seed dormancy is a condition of plant seeds that prevents germination when the seeds are under optimal environmental conditions for germination. Living, non dormant seeds germinate when soil temperatures and moisture conditions are suited for cellular processes and division; dormant seeds do...
and are dispersed
Seed dispersal
Seed dispersal is the movement or transport of seeds away from the parent plant. Plants have limited mobility and consequently rely upon a variety of dispersal vectors to transport their propagules, including both abiotic and biotic vectors. Seeds can be dispersed away from the parent plant...
by vertebrates. Each seed weighs approximately 0.25 g.
It is an evergreen species, with a new flush of leaves growing between January and April, during the dry season, when the highest light levels occur in the rainforest. This phenology
Phenology
Phenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate...
is thought to allow S. amara to photosynthesise most effectively, since the new leaves are more efficient than those they replace. It has visible, but indistinct growth rings that are on average 7 mm wide. A study of individuals in Panama found that they grow on average 8.4 mm in diameter each year, in Costa Rica, growth rates as fast as 18 mm per year have been recorded, and the stem grows constantly throughout the year. The xylem
Xylem
Xylem is one of the two types of transport tissue in vascular plants. . The word xylem is derived from the Classical Greek word ξυλον , meaning "wood"; the best-known xylem tissue is wood, though it is found throughout the plant...
vessels in mature trees range from 20 to 90 μm in diameter, with around 50 vessels present per mm2 of branch. The density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
of the wood is between 0.37–0.44 g/cm3, lower than many other species in the rainforest.
It is a fast-growing, light-demanding and shade-intolerant
Shade tolerance
In ecology, shade tolerance is a plant's abilities to tolerate low light levels. The term is also used in horticulture and landscaping, although in this context its use is sometimes sloppy, especially with respect to labeling of plants for sale in nurseries....
species. Saplings are typically one straight pole, with several compound leaves and only one point of growth. This allows the sapling to achieve the greatest vertical growth with a minimum amount of biomass. They start to branch once they are 2–5 m tall.
A study in the forest dynamics
Forest dynamics
Forest dynamics describes the underlying physical and biological forces that shape and change a forest. That is, the continuous state of change that alters the composition and structure of a forest....
plot on BCI found that between 1982 and 2000, around 65% of individuals died, with mortality highest amongst small individuals (<1 cm dbh
Diameter at breast height
Diameter at breast height, or DBH, is a standard method of expressing the diameter of the trunk or bole of a standing tree. DBH is one of the most common dendrometric measurements....
). Large trees (>20 cm dbh) are relatively rare, averaging 2.4 trees per hectare, compared to 40 trees per hectare of >1 cm dbh.
Taxonomy
Simarouba amara was first described by Jean Baptiste Christophore Fusée AubletJean Baptiste Christophore Fusée Aublet
Jean Baptiste Christophore Fusée Aublet was a French pharmacist, botanist and explorer.Born in Salon-de-Provence, he joined the French East India Company and in 1752 was sent to Mauritius to establish a pharmacy and a botanical garden. He worked there for nine years...
in French Guiana
French Guiana
French Guiana is an overseas region of France, consisting of a single overseas department located on the northern Atlantic coast of South America. It has borders with two nations, Brazil to the east and south, and Suriname to the west...
in 1775 and is the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of the Simarouba
Simarouba
Simarouba is a genus of trees and shrubs in the Simaroubaceae family, native to the neotropics. It has been grouped in the subtribe Simaroubina along with the Simaba and Quassia genera. They have compound leaves, with between 1 and 12 pairs of alternate pinnate leaflets. Their flowers are...
genus. In 1790, William Wright
William Wright (botanist)
William Wright was a Scottish physician and botanist.Born in March 1735 in Crieff, Perthshire, he studied at Crieff Grammar School and the University of Edinburgh, and obtained a medical degree at St. Andrews . He served as an apprentice with G Dennistoun in Falkirk , and became a navy surgeon in...
described Quassia simarouba, which Auguste Pyrame DeCandolle suggested was the same species as S. amara. However, because S. amara was described as monoecious by Aublet and Q. simarouba was described as dioecious by Wright, they were still regarded as separate species in 1829. By 1874, when the Flora Brasiliensis
Flora Brasiliensis
Flora Brasiliensis is a book published between 1840 and 1906 by the editors Carl Friedrich Philipp von Martius, August Wilhelm Eichler, Ignatz Urban and many others...
was published, they were considered synonymous.
Among the six species of Simarouba, two besides S. amara occur on the continent: S. glauca
Simarouba glauca
Simarouba glauca is a species of flowering tree that is native to Florida in the United States, southern Mexico, Central America, and the Greater Antilles. Common names include Paradise Tree, Aceituno, and Bitterwood. Its seeds produce an edible oil. The tree is well suited for warm, humid,...
and S. versicolor. S. amara can be distinguished from the other continental species by having smaller flowers, anthers and fruit, and straight, rather than curved petals. The leaves of Simarouba amara subsp. opaca are not glaucous
Glaucous
Glaucous is used to describe the pale grey or bluish-green appearance of the surfaces of some plants, as well as in the names of birds, such as the Glaucous Gull , Glaucous-winged Gull , Glaucous Macaw , and Glaucous...
(a bluish-grey or green colour) on their underside, whereas those of Simarouba amara subsp. typica are.
| Structure | S. amara | S. glauca | S. versicolor |
|---|---|---|---|
| Flower | 3–5 mm long | 4–7.5 mm long | 4–7.5 mm long |
| Anthers | 0.4–1.2 mm long | 1.3–2.0 mm long | 1.0–1.5 mm long |
| Petals | Straight, dull yellow-green to white | Curved, brighter yellow with a touch of orange or red | Curved |
| Fruits | 1.0–1.5 x 0.6–1.0 cm | 2.0–2.5 x 1.2–1.5 cm | 2.0–2.5 x 1.5–2.0 cm |
Common names
Simarouba amara is known by many common names, where in the Neotropics. In Bolivia it is known as chiriuana, in Brazil as marupa, marupuaba, parahyba, paraiba and tamanqueira. In Colombia it is called simaruba, in Ecuador as cedro amargo, cuna and guitarro, in French Guiana as simarouba, in Guyana as simarupa, in Peru as marupa, in Surinam as soemaroeba and in Venezuela cedro blanco and simarouba.In Europe, it was known by various names during the nineteenth century when it was used as a medicine; these names included bitter ash, bitterwood, mountain damson and stave-wood.
Distribution
The natural range of S. amara is in the Neotropics, the ecoregionEcoregion
An ecoregion , sometimes called a bioregion, is an ecologically and geographically defined area that is smaller than an ecozone and larger than an ecosystem. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural...
of Central
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. Its range extends from Guatemala
Guatemala
Guatemala is a country in Central America bordered by Mexico to the north and west, the Pacific Ocean to the southwest, Belize to the northeast, the Caribbean to the east, and Honduras and El Salvador to the southeast...
in the north, to Bolivia
Bolivia
Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
in the south and from Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
in the west, to the east coast of Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
. It has been introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
to the islands of Dominica
Dominica
Dominica , officially the Commonwealth of Dominica, is an island nation in the Lesser Antilles region of the Caribbean Sea, south-southeast of Guadeloupe and northwest of Martinique. Its size is and the highest point in the country is Morne Diablotins, which has an elevation of . The Commonwealth...
and Puerto Rico
Puerto Rico
Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...
in the Caribbean Sea, becoming naturalised in Puerto Rico. On BCI, mature trees (>10 cm dbh) are found at a frequency of 5 per hectare, in Ecuador at 0.7 per hectare and in French Guiana at 0.4 per hectare. Genetic analysis of populations suggests that it has always been relatively common within its range. It grows in rainforests and in savannah
Savannah
Savannah or savanna is a type of grassland.It can also mean:-People:* Savannah King, a Canadian freestyle swimmer* Savannah Outen, a singer who gained popularity on You Tube...
s. The seedlings of S. amara are rare in primary forest due to their light-demanding habit.
Genetics
PopulationPopulation
A population is all the organisms that both belong to the same group or species and live in the same geographical area. The area that is used to define a sexual population is such that inter-breeding is possible between any pair within the area and more probable than cross-breeding with individuals...
s of S. amara display high levels of heterozygosity indicating that it is genetically diverse
Genetic diversity
Genetic diversity, the level of biodiversity, refers to the total number of genetic characteristics in the genetic makeup of a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary....
. This is consistent with the tree outcrossing over large distances by long-distance pollen flow and that there has been sufficient long distance gene flow
Gene flow
In population genetics, gene flow is the transfer of alleles of genes from one population to another.Migration into or out of a population may be responsible for a marked change in allele frequencies...
between populations to counteract the effects of genetic drift
Genetic drift
Genetic drift or allelic drift is the change in the frequency of a gene variant in a population due to random sampling.The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces...
. A study of 478 plants from 14 populations across South America found that 24% of all allele
Allele
An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...
s occurred in only one population. A study of 300 plants on Barro Colorado Island
Barro Colorado Island
Barro Colorado Island is located in the man-made Gatun Lake in the middle of the Panama Canal. The island was formed when the waters of the Chagres River were dammed to form the lake. When the waters rose, they covered a significant part of the existing rainforest, and the hilltops remained as...
found that the heterozygosity at 5 microsatellite loci varied between 0.12 and 0.75. 8 out of the 50 alleles scored occurred in only one plant.
Reproduction
Individuals do not typically reproduce until they have a trunk diameter of 30 cm. Once mature, the trees produce flowers each year, but not all females produce fruit each year. Their flower morphology is typical of being pollinated by generalist small insects such as bees and moths. It has been reported to be pollinated by non-sphingid mothSphingidae
Sphingidae is a family of moths , commonly known as hawk moths, sphinx moths and hornworms, that includes about 1,200 species . It is best represented in the tropics but there are species in every region . They are moderate to large in size and are distinguished among moths for their rapid,...
s, but other authors have questioned whether this is correct.
Seed dispersal
Seed dispersal
Seed dispersal is the movement or transport of seeds away from the parent plant. Plants have limited mobility and consequently rely upon a variety of dispersal vectors to transport their propagules, including both abiotic and biotic vectors. Seeds can be dispersed away from the parent plant...
by vertebrates, mainly large birds and mammals, including chachalaca
Chachalaca
Chachalacas are mainly brown birds from the genus Ortalis. These cracids are found in wooded habitats in far southern United States , Mexico, and Central and South America. They are social, can be very noisy and often remain fairly common even near humans, as their relatively small size makes them...
s, flycatcher
Flycatcher
There are various families of bird termed flycatchers:* The Old World flycatchers, Muscicapidae* The Tyrant flycatchers, Tyrannidae* The Monarch flycatchers, Dicruridae* The Silky-flycatchers, Ptilogonatidae* The Fairy flycatchers, Stenostiridae...
s, motmot
Motmot
The motmots or Momotidae are a family of birds in the near passerine order Coraciiformes, which also includes the kingfishers, bee-eaters and rollers. All extant motmots are restricted to woodland or forest in the Neotropics, and the largest diversity is in Middle America. They have a colourful...
s, thrush
Thrush (bird)
The thrushes, family Turdidae, are a group of passerine birds that occur worldwide.-Characteristics:Thrushes are plump, soft-plumaged, small to medium-sized birds, inhabiting wooded areas, and often feed on the ground or eat small fruit. The smallest thrush may be the Forest Rock-thrush, at and...
es, howler monkey
Howler monkey
Howler monkeys are among the largest of the New World monkeys. Fifteen species are currently recognised. Previously classified in the family Cebidae, they are now placed in the family Atelidae. These monkeys are native to South and Central American forests...
s, tamarin
Tamarin
The tamarins are squirrel-sized New World monkeys from the family Callitrichidae in the genus Saguinus. They are closely related to the lion tamarins in the genus Leontopithecus.- Range :...
s and spider monkey
Spider monkey
Spider monkeys of the genus Ateles are New World monkeys in the subfamily Atelinae, family Atelidae. Like other atelines, they are found in tropical forests of Central and South America, from southern Mexico to Brazil...
s. Leaf cutter ants have also been observed to disperse the seeds and dense seedling
Seedling
thumb|Monocot and dicot seedlingsA seedling is a young plant sporophyte developing out of a plant embryo from a seed. Seedling development starts with germination of the seed. A typical young seedling consists of three main parts: the radicle , the hypocotyl , and the cotyledons...
carpets form in areas where they dump waste material. Seeds that are eaten by monkeys are more likely to germinate than seeds that have not. Fruit-eating phyllostomid bats have also been noted to disperse their seeds; this may aid the regeneration of forests as they disperse the seeds of later successional species while they feed on S. amara.
Based on inverse modelling of data from seed trap
Seed trap
Seed traps are used in ecology and forestry to capture seeds falling from plants, allowing seed production anddispersal to be quantified. They come in several forms, including funnel traps, sticky traps , nets and pots exposed in the field....
s on BCI, the estimated average dispersal distance for seeds is 39 m. Studying seedlings and parent trees on BCI using DNA microsatellites revealed that, in fact on average, seedlings grow 392 m away from their parents, with a standard deviation
Standard deviation
Standard deviation is a widely used measure of variability or diversity used in statistics and probability theory. It shows how much variation or "dispersion" there is from the average...
of ±234 m and a range of between 9 m and 1 km. In the forest there are many seeds and seedlings beneath reproductive females; genetic data indicate that seedlings are unlikely to be from nearby adults, but rather dispersed there by vertebrates that have fed on one tree and then moved to feed on another, defecating while in the canopy and depositing the seeds.
Physiology
Various aspects of the physiologyPlant physiology
Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants. Closely related fields include plant morphology , plant ecology , phytochemistry , cell biology, and molecular biology.Fundamental processes such as photosynthesis, respiration, plant nutrition,...
or S. amara have been studied. The stomatal conductance
Conductance
Conductance may refer to:* Electrical conductance, the ability for electricity to flow a certain path* Fluid conductance, the ability for fluid to transmit through materials* Thermal conductivity, the ability for temperatures to transmit through materials...
of the leaves, an indication of the rate at which water evaporates
Evapotranspiration
Evapotranspiration is a term used to describe the sum of evaporation and plant transpiration from the Earth's land surface to atmosphere. Evaporation accounts for the movement of water to the air from sources such as the soil, canopy interception, and waterbodies...
, of mature trees at midday range from 200 to 270 mmol H2O m−2 s−1. The leaf water potential
Water potential
Water potential is the potential energy of water per unit volume relative to pure water in reference conditions. Water potential quantifies the tendency of water to move from one area to another due to osmosis, gravity, mechanical pressure, or matrix effects such as surface tension...
s at midday range from −0.56 to −1.85 MPa
Pascal (unit)
The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre...
, averaging around −1.2 MPa. Cavitation is widespread in the trunk and the stomata do not close before cavitation occurs. Although this would normally be considered deleterious to the tree, it may buffer the leaf water potential and therefore be beneficial. The stomatal conductance and hydraulic conductance of the branches of taller trees (~30 m) are much higher than in the branches of smaller trees (~20 m). Phillips, Bond and Ryan suggested that this is probably due to the branches of taller trees having a lower leaf-to-sapwood ratio than those of small branches. Dye staining shows that cavitation is common in the branches of S. amara. They concluded that water flux in S. amara is controlled by structural (leaf area), rather than physiological (closing stomata) means.
Leaves absorb light
Absorption (electromagnetic radiation)
In physics, absorption of electromagnetic radiation is the way by which the energy of a photon is taken up by matter, typically the electrons of an atom. Thus, the electromagnetic energy is transformed to other forms of energy for example, to heat. The absorption of light during wave propagation is...
in the photosynthetically active radiation
Photosynthetically active radiation
Photosynthetically active radiation, often abbreviated PAR, designates the spectral range of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. This spectral region corresponds more or less with the range of light visible to...
(PAR) spectrum
Electromagnetic spectrum
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
at wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
s between 400 nm and 700 nm with a high efficiency, but the efficiency decreases at longer wavelengths. Generally plants absorb PAR at efficiencies of around 85%; the higher values found in S. amara are thought to be due to the high humidity
Humidity
Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...
of its habitat. The reflectance and transmittance
Transmittance
In optics and spectroscopy, transmittance is the fraction of incident light at a specified wavelength that passes through a sample. A related term is absorptance, or absorption factor, which is the fraction of radiation absorbed by a sample at a specified wavelength...
of the leaves are low at between 400 and 700 nm. The optical properties and the mass of the leaves vary depending on their location in the forest canopy, with leaves becoming thicker and more efficient as their height within the canopy increases. For their weight, however, leaves in the understory are more efficient at capturing light than leaves in the canopy.
| Absorbance Absorption (electromagnetic radiation) In physics, absorption of electromagnetic radiation is the way by which the energy of a photon is taken up by matter, typically the electrons of an atom. Thus, the electromagnetic energy is transformed to other forms of energy for example, to heat. The absorption of light during wave propagation is... (400-700 nm) |
Absorbance (700-750 nm) | Reflectance (400-700 nm) | Transmittance Transmittance In optics and spectroscopy, transmittance is the fraction of incident light at a specified wavelength that passes through a sample. A related term is absorptance, or absorption factor, which is the fraction of radiation absorbed by a sample at a specified wavelength... (400-700 nm) |
Leaf mass (g/m2) | |
|---|---|---|---|---|---|
| Understory (~2m) | 91.7% | 37.3% | 6.3% | 2.1% | 36.9 |
| Mid-canopy (~10m) | 92.8% | 41.6% | 6.1% | 1.2% | 55.4 |
| Canopy (>20m) | 93.1% | 46.1% | 5.2% | 0.5% | 135.2 |
The concentration of bioavailable phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
has been found to be higher underneath female individuals than underneath males, even though the total concentration of phosphate is equal. Rhoades et al. concluded that this difference was due to females changing the availability of phosphate, rather than females only growing in areas with high phosphate availability. This is thought to be caused either by the fruit containing high levels of phosphate which would fall off the tree and rot, or by the fruits attracting animals which deposit phosphate beneath the females. It is also possible that the sexes produce different root exudates, which affect the microbial community in their rhizosphere
Rhizosphere
The rhizosphere is the narrow region of soil that is directly influenced by root secretions and associated soil microorganisms. Soil which is not part of the rhizosphere is known as bulk soil. The rhizosphere contains many bacteria that feed on sloughed-off plant cells, termed rhizodeposition, and...
, thereby affecting phosphate availability.
The woody tissues of S. amara have been found to respire
Cellular respiration
Cellular respiration is the set of the metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate , and then release waste products. The reactions involved in respiration are catabolic reactions that involve...
at a rate of 1.24 μmol m−2 s−1, and this rate of respiration correlates positively with the growth rate of the stem. Maintenance respiration
Maintenance respiration
Maintenance respiration refers to metabolism occurring in an organism that is needed to maintain that organism in a healthy, living state...
was calculated at 31.1 μmol m−3 s−1 and this rate correlated positively with the sapwood volume.
Seedling physiology
| Nutrient | Concentration (mg/g leaf) (dry weight) |
|---|---|
| Nitrogen | 20 |
| Phosphorus | 1 |
| Potassium | 16 |
| Calcium Calcium in biology Calcium plays a pivotal role in the physiology and biochemistry of organisms and the cell. It plays an important role in signal transduction pathways, where it acts as a second messenger, in neurotransmitter release from neurons, contraction of all muscle cell types, and fertilization... |
2 |
| Magnesium Magnesium in biology Magnesium is an essential element in biological systems. Magnesium occurs typically as the Mg2+ ion. It is an essential mineral nutrient for life and is present in every cell type in every organism. For example, ATP , the main source of energy in cells, must be bound to a magnesium ion in order to... |
5 |
Experiments on BCI where trenches were dug around seedlings of S. amara, or where gaps in the canopy where made above them, show that their relative growth rate
Relative growth rate
Relative growth rate is a measure used in plant physiology to quantify the speed of plant growth. It is measured as the mass increase per aboveground biomass per day, for example as g g-1 d-1...
can be increased by both. This shows that their growth is normally limited by both above-ground competition
Competition (biology)
Competition is an interaction between organisms or species, in which the fitness of one is lowered by the presence of another. Limited supply of at least one resource used by both is required. Competition both within and between species is an important topic in ecology, especially community ecology...
for light and by below-ground competition for nutrients
Plant nutrition
'Plant Nutrition is the study of the chemical elements that are necessary for growth. In 1972, E. Epstein defined 2 criteria for an element to be essential for plant growth:# in its absence the plant is unable to complete a normal life cycle or...
and water. Competition for light is normally more important, as shown by the growth rate increasing by almost 7 times and mortality decreasing, when seedlings were placed in gaps, compared to the understory. When seedlings in gaps had a trench dug round them to prevent below-ground competition their growth increased further, by 50%, demonstrating that in gaps the seedlings are limited by below-ground competition. Trenching around seedlings in the understory did not significantly increase their growth, showing that they are normally only limited by competition for light.
Larger seedlings are more likely to survive the dry season on BCI than smaller seedlings. Density-dependent inhibition occurs between seedlings: they are more likely to survive in areas where fewer seedlings of S. amara are growing. A study on individuals on BCI found that this pattern may be caused by differences in soil biota rather than by insect herbivores or fungal pathogens. Observations based on the distance of seedlings from their parents indicate that the Janzen-Connell hypothesis
Janzen-Connell hypothesis
The Janzen-Connell hypothesis is a widely accepted explanation for the maintenance of tree species biodiversity in tropical rainforests. It was published independently in the early 1970s by Daniel Janzen and Joseph Connell...
applies to seedlings of S. amara: they are more likely to survive away from their parents as they escape pests such as herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s and plant pathogens which are more common underneath the parent trees.
Sapling physiology
Saplings of S. amara are light demanding and are found in brighter areas of the rainforest compared to Pitheullobium elegans and Lecythis ampla seedlings. A study at the La Selva Biological Station found the leaves weigh approximately 30 g/m2 (dry weight), similar to P. elegans, but around double the weight of L. ampla. The photosynthetic capacityPhotosynthetic capacity
Photosynthetic capacity is a measure of the maximum rate at which leaves are able to fix carbon during photosynthesis. It is typically measured as the amount of carbon dioxide that is fixed per metre squared per second, for example as μmol m-2 sec-1....
of the leaves of S. amara is higher than that of the other two species, averaging around 6 μmol m−1 s−1. Dark respiration
Cellular respiration
Cellular respiration is the set of the metabolic reactions and processes that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate , and then release waste products. The reactions involved in respiration are catabolic reactions that involve...
is on average 0.72 μmol m−1 s−1, higher than that of the other two species. The maximum photosynthetic rate correlates with both stem diameter and vertical growth. Diffuse light is thought to be more important for seedling growth than sunfleck
Sunfleck
Sunflecks are brief increases in solar irradiance that occur in forest understories when sunlight is able to directly reach the ground. They are caused by either wind moving branches in the canopy or as the sun moves during the day...
s. Another study of saplings at La Selva found that they grew 7 cm yr−1 in height and 0.25 mm yr−1 in diameter. On average they had nine compound leaves, a leaf area index
Leaf Area Index
Leaf Area Index The Global Climate Observing System defines LAI as "one half the total green leaf area per unit groundsurface area. On sloping surfaces, the LAI should be projected to the normal to the slope. LAI is expressed in terms of square meters of leaf per square meter of ground...
of 0.54 and the total surface area of their leaves was 124 cm2. The saplings that had the lowest leaf area were most likely to die during the study and those with a larger leaf area grew faster than other saplings.
A study of saplings between one and four centimeters in diameter on BCI found that the growth of saplings did not vary depending on which species grew near them, contrary to predictions that density-dependence inhibition occurs. A model based on these findings predicted that saplings with a diameter of 2 cm are able to grow at a maximum rate of 13 mm yr−1 and that if another tree with a diameter of 10 cm is growing within 5 m of the sapling, its growth is only reduced to 12 mm yr−1, indicating that they are not affected by crowding. Trees growing more than 15 m away from a sapling do not affect their growth.
Ecology
Lianas are relatively rare on mature (>20 cm dbh) individuals of S. amara, compared to other trees on BCI, with only around 25% having lianas growing on them. Putz suggested that this may be due to the trees having large leaves, but the mechanism by which this would reduce the number of lianas is unknown. Smaller individuals also have fewer lianas and woody hemi-epiphyteEpiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...
s than other species of tree in the same forests.
The alianthus webworm (Atteva aurea) and other members of the Atteva genus have been recorded to eat the new shoot tips of S. amara in Costa Rica. The larvae of the butterfly species, Bungalotis diophorus feed exclusively on saplings and treelets of S. amara. Two termite
Termite
Termites are a group of eusocial insects that, until recently, were classified at the taxonomic rank of order Isoptera , but are now accepted as the epifamily Termitoidae, of the cockroach order Blattodea...
species have been observed living on S. amara in Panama, Calcaritermes brevicollis in dead wood and Microcerotermes arboreus nesting in a gallery on a branch. Bullet ants (Paraponera clavata) have been found to nest at the base of S. amara trees. The Hemiptera
Hemiptera
Hemiptera is an order of insects most often known as the true bugs , comprising around 50,000–80,000 species of cicadas, aphids, planthoppers, leafhoppers, shield bugs, and others...
, Enchophora sanguinea
Enchophora sanguinea
Enchophora sanguinea is a species of lantern bug, a type of hemipteran, found in Central and South America. It was first described by William Lucas Distant in 1887. They are long. Their colour varies, but is normally red to green; they have a scimitar-shaped process on their heads...
(Fulgoridae) has been found preferentially on the trunks of S. amara.
Materials
Simarouba amara is used locally for producing paper, furniture, plywood and matches and is also used in construction. It is also grown in plantations, as its bright and lightweight timber is highly sought after in European markets for use in making fine furniture and veneerWood veneer
In woodworking, veneer refers to thin slices of wood, usually thinner than 3 mm , that are typically glued onto core panels to produce flat panels such as doors, tops and panels for cabinets, parquet floors and parts of furniture. They are also used in marquetry...
s. The wood dries rapidly and is easy to work with normal tools. It is creamy white to light yellow in colour, with a coarse texture and a straight grain. It has to be treated
Wood preservation
All measures that are taken to ensure a long life of wood fall under the definition wood preservation . Apart from structural wood preservation measures, there are a number of different preservatives and processes that can extend the life of wood, timber, wood structures or engineered wood...
to prevent fungi, wood borers and termite
Termite
Termites are a group of eusocial insects that, until recently, were classified at the taxonomic rank of order Isoptera , but are now accepted as the epifamily Termitoidae, of the cockroach order Blattodea...
s from eating it. The heartwood has a density of 0.35–0.45 g/cm3. It has been noted to be one of the best species for timber that can be grown in the Peruvian Amazon
Peruvian Amazon
The Peruvian Amazon is the area of the Amazon jungle included in the territory of Peru, from the east of the Andes to borders with Ecuador, Colombia, Brazil and Bolivia. This region comprises 60% of the country and is marked by a large degree of biodiversity...
, along with Cedrelinga catenaeformis, due to its rapid growth characteristics. The Worldwide Fund for Nature recommend that consumers ensure S. amara timber is certified by the Forest Stewardship Council
Forest Stewardship Council
The Forest Stewardship Council is an international not-for-profit, multi-stakeholder organization established in 1993 to promote responsible management of the world’s forests. Its main tools for achieving this are standard setting, independent certification and labeling of forest products...
so that they do not contribute to deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....
. Wood shavings of S. amara have been used in animal bedding leading to the poisoning of horses and dogs.
Medical
The leaves and bark of S. amara have been used to treat dysenteryDysentery
Dysentery is an inflammatory disorder of the intestine, especially of the colon, that results in severe diarrhea containing mucus and/or blood in the faeces with fever and abdominal pain. If left untreated, dysentery can be fatal.There are differences between dysentery and normal bloody diarrhoea...
, diarrhea
Diarrhea
Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
, malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
and other illnesses in traditional medicine
Traditional medicine
Traditional medicine comprises unscientific knowledge systems that developed over generations within various societies before the era of modern medicine...
in areas where it grows. In 1713, it was exported to France where it was used to treat dysentery, being an effective treatment during epidemics between 1718 and 1725. In 1918 its effectiveness was validated by a study where soldiers in a military hospital were given a tea made of the bark to treat amoebic dysentery
Amoebic dysentery
Amoebic dysentery is a type of dysentery caused primarily by the amoeba Entamoeba histolytica. Amoebic dysentery is transmitted through contaminated food and water. Amoebae spread by forming infective cysts which can be found in stools, and spread if whoever touches them does not sanitize their...
. In a 1944 study, the Merck Institute found it was 92% effective at treating intestinal amoebiasis in humans. During the 1990s, scientists demonstrated it could kill the most common cause of dysentery, Entamoeba histolytica
Entamoeba histolytica
Entamoeba histolytica is an anaerobic parasitic protozoan, part of the genus Entamoeba. Predominantly infecting humans and other primates, E. histolytica is estimated to infect about 50 million people worldwide...
, and species of Salmonella
Salmonella
Salmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which grade in all directions . They are chemoorganotrophs, obtaining their energy from oxidation and reduction...
and Shigella
Shigella
Shigella is a genus of Gram-negative, nonspore forming, non-motile, rod-shaped bacteria closely related to Escherichia coli and Salmonella. The causative agent of human shigellosis, Shigella causes disease in primates, but not in other mammals. It is only naturally found in humans and apes. During...
bacteria that cause diarrhea. The main biologically active compounds found in S. amara are the quassinoids, a group of triterpene
Triterpene
Triterpenes are terpenes consisting of six isoprene units and have the molecular formula C30H48.The pentacyclic triterpenes can be classified into lupane, oleanane or ursane groups.Animal- and plant-derived triterpenes exist, such as:*squalene...
s, of which the most therapeutic are ailanthinone, glaucarubinone, and holacanthone. These have been reported to kill protozoa, amoeba, Plasmodium
Plasmodium
Plasmodium is a genus of parasitic protists. Infection by these organisms is known as malaria. The genus Plasmodium was described in 1885 by Ettore Marchiafava and Angelo Celli. Currently over 200 species of this genus are recognized and new species continue to be described.Of the over 200 known...
(the cause of malaria) and also cancerous human cells. The anti-malarial properties were first investigated by scientists in 1947; they found that in chickens, 1 mg of bark extract per 1 kg of body weight had strong antimalarial activity. In 1997 a patent was filed in the United States for using an extract in a skin care product.
External links
- Simarouba amara discoverlife.org
- Simarouba amara Missouri Botanical GardenMissouri Botanical GardenThe Missouri Botanical Garden is a botanical garden located in St. Louis, Missouri. It is also known informally as Shaw's Garden for founder Henry Shaw, a botanist and philanthropist.-History:...
- Photographs of wood structure