The Ecology of Trees in the Tropical Rain Forest (Cambridge Tropical Biology Series)

Cambridge Core - Plant Sciences - The Ecology of Trees in the Tropical Rain Forest - by Series: Cambridge Tropical Biology Series; Subjects: Ecology and.
Table of contents

Yet a good understanding of the trees is essential to unravelling the workings of the forest itself. This book aims to summarise contemporary understanding of the ecology of tropical rain-forest trees. The emphasis is on comparative ecology, an approach that can help to identify possible adaptive trends and evolutionary constraints and which may also lead to a workable ecological classification for tree species, conceptually simplifying the rain-forest community and making it more amenable to analysis.

Review of the hardback: It bravely tackles the bigger issue of why different species of tropical tree adopt different solutions to complex environmental problems and looks for patterns that may have adaptive or evolutionary significance. There is something for everyone - it is difficult to name a topic that is not dealt with. The growing tree 3. Seeds and seedlings 6. Classificatory systems for tropical trees Bibliography Index. Turner , Singapore Botanic Gardens This title is available for institutional purchase via Cambridge Core Cambridge Core offers access to academic eBooks from our world-renowned publishing programme.

The Lichenologist is the premier scientific journal devoted exclusively to the study of lichens worldwide. Bird Conservation International is a quarterly peer-reviewed journal that seeks to promote worldwide research and…. Seed Science Research, the official journal of the International Society for Seed Science, is an international journal…. International Journal of Tropical Insect Science is the only journal devoted exclusively to the latest research in….

Nutrition Research Reviews offers a comprehensive overview of nutritional science today. By distilling the latest…. Plant Genetic Resources is an international journal which provides a forum for describing the application of novel…. With a focus on the tropical and sub-tropical regions of the world, Experimental Agriculture publishes the results…. Renewable Agriculture and Food Systems is a multi-disciplinary journal which focuses on the science that underpins…. Journal of Tropical Ecology publishes papers in the important and now established field of the ecology of tropical….

Edinburgh Journal of Botany is an international journal of plant systematics covering related aspects of biodiversity,….

Refine your editions:

Journal of Applied Animal Nutrition publishes leading research in all aspects of animal feed science and nutrition…. Please register or sign in to request access. In the fast-growing species, the huge leaves at the ends of the branches produce a crown with an outer covering of a layer or two of leaves that is supported with relatively low investment in wood. These tropical parasol trees can be considered neotenic: All these factors are likely to act as selective pressures in the evolution of crown form. Neea chlorantha was found in sites with more direct overhead illumination on average than Rinorea viridifolia, generally small gaps in the canopy.

Neea was more highly branched with a shell of drooping leaves on the outside of the crown. Rinorea had whorled branches in tiers with planar foliage arrays. These can be physical where scale-dependent forces necessitate proportionally less, or more, investment in certain organs if the organism is to maintain a uniform likelihood of damage or destruction from the force concerned.

For example, many individual and stand characteristics are often estimated from tree bole diameter measurements. The most frequently studied allometric relationship of trees is that between stem diameter D and height H. A major goal has been to assess the magnitude of the allometric constant a where D. A free-standing column of uniform taper and material composition requires its diameter to increase faster than the height in order to maintain a constant mechanical stability.

Studies of the height—diameter relation for tropical trees over a range of heights, either for individual species or for multispecies samples, show that elastic similarity is probably a reasonable approximation for the height—diameter relation Rich et al. This implies that young trees have relatively more slender trunks than large old ones. This is a fact of which most people are consciously unaware yet use subconsciously in determining the relative height of trees when no scale object is available to view.

The solid line is a linear regression. The absence of a peripheral cambium means that palm stems have to be produced at almost their maximal diameter when they are formed beneath the apical meristem. Other deviations may be related to relative crown development. This was probably because it had a proportionally larger crown than the rest.

It is possible to predict the diameter at which a wooden column of standard mechanical properties and taper will buckle under its own weight. Such analyses for tropical trees Rich et al.


  1. HighGasm is Edible Personal Lubricant For Men and Women;
  2. Unlocking potential with the best learning and research solutions?
  3. The Words and Music of Patti Smith (The Praeger Singer-Songwriter Collection).
  4. The 25th Colony.
  5. The ecology of trees in the tropical rain forest / I.M. Turner - Details - Trove.
  6. Well wait no longer, You can now join our collective and order HighGasm Today!?
  7. Download The Ecology Of Trees In The Tropical Rain Forest Cambridge Tropical Biology Series.

The trunk diameters of eight species of canopy and emergent tree in the height range 6—24 m were 1. However, this approach to design safety can be criticised on several grounds. Firstly, such studies have generally assumed uniform wood 44 2 The growing tree properties with tree size but this may not be the case, particularly in species with low-density wood see above.

The narrower safety margin of the fast-growers may be a risk-taking strategy to increase investment in reproduction in large individuals. Secondly, the minimum diameter is derived for a crownless tree. It is becoming clear that many species are not truly linear on the height— diameter log—log plot. As the trees reach very large size their height Figure 2.

The bold line indicates the minimum diameter required to prevent buckling in wooden columns. There are several possible explanations for this King Large trees are more exposed to strong winds and therefore require thicker stems to cope with the extra loading. Large trees also tend to develop wider crowns that would also need more support.

Tree species may have a pre-determined maximal height and once this is attained height growth ceases. However, if the tree is to continue to live, it must carry on increasing in stem diameter to form new vascular tissues. Species with high adult mortality may be physiologically capable of reaching large size, but demographic factors mean that they rarely do so. Thomas a,b has studied the allometric relationships of nearly 40 species of tree from six genera in the lowland rain forest at Pasoh in Malaysia. There was a negative relation between wood density and H' Fig.

There was a strong tendency for a change in the slope of the H—D regression that coincided with the typical size at the onset of reproductive activity for the species. It is possible that allocation to reproduction is what reduces the rate of height growth. Bark The successful use of bark characters to identify trees in the forest indicates both the considerable variation among species and the constancy of bark form within a species.

Bark thickness has been shown to increase with tree girth Roth ; Hegde et al. Bark protects the sapwood from attack. Interestingly, the fast-growing, softwooded Miconia argentea showed the slowest wound closure rate. The subterranean portion of the forest is hidden from view and poorly understood. Coarse roots are generally woody and provide a mechanical and conductive service to the tree. These play an extremely important role in mineral nutrition and possibly in other areas of tree physiology.

The morphology of tree root systems is complex. Aerial roots are to be found in most tropical forests, and are particularly abundant in forests with periodic or continuous inundation by fresh or salt water, but they are far from common in most well-drained forests, unless buttresses are considered as aerial roots. Another major means of classifying root systems is by their relative depth.

Some trees have much of the root system close to the soil surface, sometimes with major roots running over the top of the soil. Other species have greater development of roots at depth. Tree roots may descend a long way into the soil. These deep roots reach to the permanent water table, allowing rain forest to exist in an area where the dry season is both prolonged and severe, averaging 5 months with less than mm of rain.

A considerable portion of the Amazon rain forests probably requires very deep roots to survive. They found that the shrub or treelets had shallower root systems Fig. However, the relative scarcity of deep roots in the shrubs may make them more susceptible to drought than the saplings. A repeat of the shrub versus sapling comparison for species at Andulau in Brunei Becker et al.

Root hemi-parasites A relatively few tropical rain-forest tree species, restricted to the order Santalales, produce haustoria from their roots Fineran These Roots 49 Figure 2. Copyrighted by the Association for Tropical Biology, P. Box , Lawrence KS Multi-species surveys of mycorrhizal types in tropical rain forests Site study No.

It is likely that the hemi-parasites extract water and other contents e. Self-parasitism haustorial connections to other roots of the same plant is readily observed in such species that occur in the families Santalaceae, Olacaceae and Opiliaceae. They are mostly shrubby, often scandent, but some, such as Scleropyrum, are quite large trees. Mineral nutrition It is dangerous to generalise, but typically tropical rain forests grow on strongly acidic soils, low in concentrations of available nutrients required by the trees.

Tropical trees need to be tolerant of high free aluminium concentrations, although there has been relatively little research on this in wild species. The nutrient inputs to the soil from the decomposition of the forest litter are likely to be large in comparison to the amounts being released by the mineral soil. However, toxicity due to free aluminium or free protons may also deter root growth in the mineral soil.

Endogonales, Glomales bacteria Actinomycete: Frankia — storage of nutrients? Calothrix Actinorhizal association Coralloid roots Leguminosae, few species, Parasponia Ulmaceae Myricaceae, Casuarinaceae bacteria Rhizobium sensu lato Rhizobial nodulation important important? There are probably about species of VAM fungi, although as they are primitive and without sexual stages there are few characters available for detailed systematic analysis Allen et al.

VAM fungi are cosmopolitan and seem to have a wide range of hosts. In tropical roots, VAM fungi rarely form arbuscules, but coils of hyphae are common in host cells Alexander There are probably over species of EM fungi world-wide Allen et al. The EM fungi produce a sheath or mantle of hyphae over the surface of the infected root, and a network of hyphae running between cells within the epidermis of the root called the Hartig net.

Relatively few tropical tree species have EM. Notable groups that do, include all Dipterocarpaceae and Fagaceae, many Leguminosae subfamily Caesalpinioideae and Myrtaceae subfamily Leptospermoideae. In general, EM fungi are more vagile than VAM species because of aerial spore release and much smaller spore size. It is interesting to note the distinction between the relatively few species of VAM fungi forming symbioses with many species of vascular plant and the high diversity of EM fungi restricted to a much smaller number of plant hosts.

Lowland tropical soils frequently have very low concentrations of available phosphorus and it appears that mycorrhizas improve the supply of P to the root or are cheaper ways of obtaining it. There are several potential mechanisms for increased rates of P uptake by mycorrhizal plants Bolan The exploration of greater soil volumes by the mycelia of mycorrhizal fungi.

The faster movement of P into fungal hyphae than roots. The solubilisation of soil P not available to roots. There is however, little evidence for this. Mycorrhizal fungi may be able to solubilise P by excreting organic acids and phosphatases.


  1. Wertkonflikte in Unternehmen: Eine erweiterte organisationstheoretische Analyse von Korruption (Germ.
  2. The Secrets of Angel Healing!
  3. 5 editions of this work.
  4. The Colorful Life of a Signal Corp Soldier in WWII.
  5. Chemistry and Application of H-Phosphonates.

Unequivocal evidence that mycorrhizal fungi do actually contribute plant-unavailable P to host plants is still being sought. Mycorrhizas may also be able to assist the host plant by transferring nutrients other than P. Mycorrhizal fungi are often associated with the litter layer and so-called direct cycling has been proposed as an advantage of possessing mycorrhizal symbioses. Direct cycling is the transfer of nutrients from the decaying litter to the root by the action of the mycorrhizal fungus breaking down the organic matter. Mycorrhizas may also assist in water uptake, tolerance of the adverse conditions in the soil, and resistance to root pathogens Table 2.

EM have the advantage over VAM in that the fungi generally penetrate into the soil even further and are more long-lived. In fact, more than one plant can be infected by the same EM mycelium and the fungus may become a conduit for carbon transfer between plants. This raises the possibility that deeply shaded seedlings might be able to survive by tapping into the EM network of surrounding trees. VAM Torti et al. EM Mycorrhizas Table 2.

Two groups Hart et al. These forests were generally dominated by a single species of caesalpinoid legume, e. These monodominant forests are probably not just early stages in succession. They generally occur on soils low in nutrients, although not extremely so. Does the possession of EM make a species competitively superior over VAM species on low-nutrient sites? There does not seem to be any very strong evidence for this.

Dipterocarpaceae, the most obligate of EM tropical trees, are represented by many species in rain forests across a range of soil fertilities in Sri Lanka and West Malesia. In a very detailed study of the P relationships of forest trees in Cameroon, Newbery et al. It is notable that many of the EM monodominants are masting species, and it may be that masting and the production of large seeds with limited powers of dispersal are what allow the species to dominate the landscape patches they occupy.

In conclusion, the possession of EM may be involved in the dominance of certain tropical forests by one or a few species, but more concrete evidence is needed before it can be accepted that EM are competitively superior to VAM. The fact that VAM and EM are mixed together in most tropical forests, and 56 2 The growing tree may simultaneously infect the same tree, indicates that dominance of one over the other is unlikely.

However, it may be simplistic to assume that mechanisms of supplementing nitrogen income are an evolutionary response to low nitrogen availability. The commonest such relationship is the legume nodule containing Rhizobium.

Cambridge Tropical Biology Series

Some cycads have cyanobacteria associated with their roots that can reduce nitrogen from the air. This has now been split into several smaller genera. Parasponia Ulmaceae , a genus of small trees from New Guinea and Australia, is the only non-legume known to be naturally nodulated with rhizobia. Interestingly, the structure of the Parasponia nodule is more similar to the Frankia nodule of actinorhizal plants than to the legume nodule Soltis et al. Frankia is an actinomycete: Among vascular plants world-wide, 25 genera in eight families are known to be actinorhizal Moiroud ; Huss-Danell Thus actinorhizal species are rarely Roots 57 found in lowland tropical rain forest, and do not play a major role in its nutrient economy.

These are apogeotropic gravity-insensitive roots usually located near the soil surface. Cycads are found throughout the tropics and are common in some lowland rain forests. It has generally been believed that, with the exception of the legume— rhizobia relationship, vascular plant—micro-organism symbioses are somewhat scattered through the higher-plant phylogeny with the implication that symbioses evolved many times.

Cambridge Tropical Biology Series

However, recent use of DNA sequences to generate phylogenetic trees has shown a relatively narrow phylogenetic base for the actinorhizal symbiosis Soltis et al. Both symbioses and the legumes are centred within the rosid clade, a fairly discrete group of the higher eudicots see Fig. The scattered presence of EM in groups of angiosperms outside the rosid line needs explaining under this hypothesis, however.

Free-living algae or lichens may grow as tiny epiphylls on the leaves of trees. See page 82 for more details on the bacterial leaf-nodule symbiosis. Plants that are habitually inhabited by ants may absorb nutrients from the waste of the ant colony. There is one report of uptake of nutrients from domatia of a tropical tree.

The ants on the Tococa plants appear to be 58 2 The growing tree sustained entirely from honeydew secretions of scale insects in the leaf domatia and by eating glands on the leaf surface. Therefore, any absorption of nutrients by the leaf domatia will very largely be recycling of material originating from the plant. Labelling experiments failed to demonstrate any uptake by stem domatia of Macaranga Fiala et al. Plants in such sites that can obtain sole access to the nutrients released by decomposition from an amount of litter may be at an advantage.

This has been the argument put forward to provide a functional explanation of litter trapping by plants Raich A basket arrangement of leaves or branches will catch falling leaves where they can decompose. Agrostistachys is a genus of understorey treelets that often has the litter-catching form. Canopy trees may also develop adventitious roots to exploit nutrients in the debris under epiphytes Nadkarni The presence of damp epiphytes and humus or sponges soaked in nutrient solution stimulated the development of adventitious roots from the branches of the neotropical montane tree Senecio cooperi Nadkarni Janzen a conjectured that being hollow might be an advantage to big, old trees if it allows some recycling of nutrients locked away in the heartwood and exploitation of waste products from roosting or nesting vertebrates.

Bruijnzeel hypothesised that the multi-stemmed form seen quite commonly in species from heath and upper montane forests might have an advantage in nutrient capture. There has been no experimental demonstration that this is the case. Most studies of nutrients and their cycling in tropical forests have concerned multi-species stands. A question of considerable interest is which mineral nutrient is in shortest supply to the trees and hence limits growth if light and water are available in adequate amounts. Several approaches have been employed in an attempt to answer this question: These generally involve growing a test plant in pots of forest soil under a variety of nutrient addition treatments.

The test plant may be herbaceous often a crop plant , or it may be a woody species. Seedlings or cuttings have to be the subjects of such studies for logistic reasons. These will be referred to in more detail in a later chapter. For instance, the likelihood of mycorrhizal infection may be reduced in pots. Litter production and nutrient concentration. Vitousek found a tighter correlation between litter production and litter phosphorus P concentration than that with litter nitrogen or calcium concentrations across many tropical forest sites.

Correcting for climatic variables maintained the correlation with P. Silver reported that litterfall mass per unit of P contained inverse of P concentration was negatively correlated with extractable mostly montane sites and total montane and lowland sites soil P in a similar study. Again N and Ca were much weaker correlates. In an unreplicated treatment application, montane forest in Jamaica showed a similar response Tanner et al. However, old growth stands at m in Hawaii did not show a growth improvement after N addition Vitousek et al.

Element accumulation Surveys of the elemental concentrations within tropical trees have shown that some species accumulate various elements to much higher concentrations than others do. For instance, in a survey of the bark concentrations of 15 elements among species in a forest in Sumatra Masunaga et al. Aluminium was the commonest element to be accumulated. A similar pattern was observed for leaf samples from the same forest Masunaga et al.

Aluminium-accumulating shrubs from southeast Asia Melastoma malabathricum, Urophyllum spp. Leaves are essentially the organs of photosynthesis. With extremely few exceptions, tropical rain-forest trees perform C3 photosynthesis Medina There are two tree species of Euphorbia E. Despite the uniformity in the basic biochemistry of photosynthesis among trees in the tropical rain forest, there is generally a large diversity of leaf form represented.

Compound leaves are common, including some quite bizarre Leaf form and physiology 61 forms such as those found in members of the Araliaceae. They vary between positions on the same tree at any one time, with age of the tree, with the growth environment of the tree, and among individuals of the same species due to both genetic and environmental factors.

The description of this variation is an important activity for plant ecologists, but elucidating why leaf form and performance vary with environment in a manner that is, to some extent, predictable must be the ultimate goal. First put forward by Bloom et al. Photosynthetic rates of leaves are usually measured as the net rate of carbon uptake or oxygen evolution per unit area or per unit mass fresh or dry of leaf. A leaf of low leaf mass per unit area LMA may have low area-based photosynthetic rates, but its massbased rate may be high.

However, it may not just be instantaneous rates of return that are important: In sites where nutrient supply is limiting growth, the investment of that nutrient in photosynthesis may be more important than dry matter as a whole. However, it is possible that in still-air conditions boundary-layer resistance might limit photosynthetic rates.

Similarly, studies of canopy leaves in Panama found that under conditions of high stomatal conductance and low wind speeds transpiration becomes decoupled from stomatal conductance Meinzer et al. Size, shape and other structural characteristics Leaf size has classically been dealt with in descriptive vegetation ecology by reference to leaf size classes. He found that a series based on 9 produced a system that lent itself more meaningfully to the description of vegetation types across the globe than one based on Webb , while investigating the tropical vegetation of Queensland, Australia, found that many of the forests he was studying fell into the mesophyll-dominated class but there was still a distinction in types.

To provide a means of doing so, he divided the mesophyll class into two, recognising the notophyll class The mesophyll sensu Raunkiaer leaf size is the commonest among tree species in lowland tropical rain forests Table 2. Usually at least three quarters of species belong to this group. Leaf sizes in various lowland tropical rain forests Values given are the percentage of the species sampled in each of the leaf size classes of Raunkiaer. The relative rarity of toothed leaves and other non-entire margin forms in the tropical rain forest is well enough established for palaeobotanists to use the frequency of toothing in leaf fossil assemblages, together with leaf size, to infer the type of climate under which the vegetation represented by the assemblage grew Wiemann et al.

There are two basic angiosperm leaf venation patterns: Leaves of temperate deciduous trees are frequently craspedodromous with a toothed margin, but those of tropical rain-forest trees are more likely to be brochidodromous with an entire margin. The hydrodynamic model also highlighted the limitations of the craspedodromous design.

The delivery of water to cells farthest away from the terminal ends of the veins, i. This probably explains the toothed leaf margins of many craspedodromous leaves. The tissues on the leaf margin that would be vulnerable to dehydration or over-heating because of the low rate of water supply are simply not formed, 64 2 The growing tree Figure 2. There has been considerable speculation about the advantages of having a means of increasing the rate of drainage of water from the surface of a leaf Richards These include reduced periods of a water layer obscuring the incoming radiation and leaching minerals, particularly potassium, from the leaf tissues, and the likelihood of water encouraging the growth of epiphylls.

A shrubby species of Piper in the montane forests of Costa Rica Leaf form and physiology 65 was shown to drain drops of water from leaves at a slower rate when the drip-tip was removed Lightbody However, no allowance was made for drop volume. Drip-tips appear most pronounced on the leaves of tree saplings growing in the shade Roth and in species with pinnate leaves Rollet Along gradients of increasing seasonality of rainfall there is usually an increased proportion of drought-deciduous species and leaf size tends to decrease Gentry There is considerable variation both within and among tropical forests and forest types in leaf structural characteristics such as leaf mass per unit area LMA , lamina thickness, anatomical features and concentrations of nutrients Figs.

The collation of data from published reports on leaf properties does not show such a clear trend as is generally described in the literature. The expectation is for the leaves of species from higher or more infertile sites to be smaller and thicker, with more dry mass per unit area, and probably volume, and to have lower concentrations of important nutrients Grubb ; Turner The typical leaves of lowland heath and upper montane forests in the tropics can be referred to as sclerophylls.

Frequently the midrib and veins are tougher than the intercostal region of the lamina Lucas et al. It is not easy to derive an average toughness or strength for the leaf, and in practice pre-determined fracture paths have to be chosen for comparative purposes. A more direct study of leaf form on one mountain, Gunung Silam in Borneo, has shown a trend of increasing LMA with altitude Bruijnzeel et al. Grubb a reported a positive correlation between LMA and leaf size for species from caatinga in Venezuela 66 2 The growing tree Figure 2.

Circle, mesophytic lowland forest; triangles, lowland heath forest; squares, montane forest.

NPPR, non-palisade to palisade tissue thickness ratio in the mesophyll. Lamina thickness more convincingly distinguishes the supposedly scleromorphic types from more mesophytic lowland forest Fig. However, non-palisade to palisade tissue thickness ratios in the mesophyll NPPR do not appear to show any consistency in distinguishing forest types. Montane forests tend to have a lower density of stomata than lowland ones Fig.

The canopy leaves of mesophytic lowland forests can be as tough as those of heath forests Turner et al.

Upcoming Events

Heath and montane forest species do appear to have generally lower foliar concentrations of major nutrients Fig. Immature leaves lose area to herbivores at 5—25 times the rate of fully enlarged, mature leaves Table 2. Pathogens are also a major cause of leaf damage. Leaves are attractive to herbivores and pathogens because they are more nutritious than other, regularly available, parts of the plant. In particular, they have higher protein concentrations than other plant organs. This must provide strong selection pressure in favour of 68 2 The growing tree Table 2.

Rates of herbivory in tropical rain-forest tree species Value in parentheses after each entry is the number of species included. However, there may be an alternative strategy if there is a cost to defence in terms of reduced growth rates. If the production of defences uses resources that would otherwise go to growing more plant tissue, then in certain circumstances there may be selection in Leaf form and physiology 69 Figure 2. Bars represent standard error. However, most plants do have some mechanisms of defence. The defences of tropical forest trees Plants are attacked by a wide range of herbivores and pathogens.

More examples can be found in Chapter 5. Materials that increase the strength and toughness of the plant body increase the work to be done by the herbivore during feeding. Cell wall materials such as cellulose and lignin are the major structural components of plant tissues. The disposition of cells with thick walls is the major determinant of the mechanical properties of plant tissues Lucas et al. The terms spine, thorn and prickle and others variously used for spiny plant parts await a universally agreed system of application.

Plant spines are often hardened by accumulations of inorganic crystalline substances such as silica or calcium salts. Perhaps the most notable group is the palms. Flightless grazing ducks and geese, exterminated after Polynesian settlement of the islands, have been invoked as the selection pressure for these defences Givnish et al. A layer of hairs may physically obstruct insects and other tiny herbivores from attacking a plant. They may be hard and sharp through inclusion of crystalline materials, strongly hooked, sticky, stinging or contain toxins.

Of species from Venezuela studied by Roth , only 15 had a dense covering of hairs, and this was restricted to the leaf undersurface in all cases.


  • The Cambridge Companion to Hume (Cambridge Companions to Philosophy).
  • The Ecology of Trees in the Tropical Rain Forest by I. M. Turner.
  • Bear, Otter, and the Kid (Bear, Otter, and the Kid Chronicles Book 1).
  • .
  • The Ecology of Trees in the Tropical Rain Forest - I. M. Turner - Google Книги!
  • .
  • Download The Ecology Of Trees In The Tropical Rain Forest Cambridge Tropical Biology Series.

    • They investigated the ant-protected euphorb Endospermum labios in New Guinea. This species occurs as what were believed to be genetically determined glabrous and hairy morphs. Colony foundress queens did not appear to make plant-host choice based on pubescence, but they were more successful on the glabrous morph. These can vary in shape from rounded to sharply pointed structures. Otherwise the hardness of crystalline inclusions can wear teeth or mandibles of herbivores. Approximately out of species examined from South America mostly Surinam had silica grains in the wood ter Welle These may be distasteful or toxic, but they can also deter herbivores through the physical property of stickiness or by hardening rapidly on exposure to air.

    When the plant is damaged the contents of the canals pour into the wound. They may even be under pressure and squirt out rapidly. Gluey secretions can gum up insect mouthparts. Herbivores may waste time and energy cleaning themselves of sticky exudates from wounds that they create in the plant. Families such as the Apocynaceae, Sapotaceae, Guttiferae and Moraceae, and Euphorbiaceae subfamily Crotonoideae are well known for latex production. The Burseraceae and Dipterocarpaceae are highly resinous. These defences are often found in seeds, but may also occur in leaves and other plant parts.

    It is an analogue of arginine. Hypoglycin A is found in unripe fruits and the funicle of the sapindaceous tree Blighia sapida. Seeds of Lecythis ollaria contain seleno-cystathionine, a toxic analogue of cys- 74 2 The growing tree Table 2. They are complex and varied in structure and biochemical properties, but tend to be bitter to taste and are frequently toxic to animals. These have mostly shown quite low frequency of alkaloid-positive species.

    The one exception, although this has a smaller sample size than the rest, is the rain forest at Kibale, Uganda, where half the species tested gave positive results. Despite the general rarity of alkaloidal trees, lowland tropical rain forests have the highest frequency and mean concentration of alkaloids of any major vegetation type Levin On the other hand, Guttiferae, Melastomataceae, Myrsinaceae, Myrtaceae and Sapindaceae are notable for the presence of few, if any, alkaloidal species.

    The main ordeal poisons of Africa are another group of legume alkaloids from the genus Erythrophleum Neuwinger Cyanogenic glycosides generate cyanide when the CN group they contain is cleaved from the sugar moiety of the glycoside molecule. They provide the commonest form of cyanogenesis in plants.

    Cyanide interferes with the cytochrome system thus inhibiting the terminal part of the main respiration pathway in cells. In a survey of tree and shrub species from Costa Rica only 20 4. Woody plants probably show a lower frequency of cyanogenesis than herbaceous species. A wide range of complex molecules, mostly synthesised via the shikimic acid pathway, can be included in the class of phenolic compounds. Alkaloids and terpenes can also be phenolics.

    Tannins are a complex set of polyphenolic compounds. They cause the astringency found in many plant products and are the group of phenolic compounds most often associated with plant defence. This property is employed in their traditional use of tanning leather.

    Tanning makes the leather much less susceptible to microbial decay by binding the proteins in the animal skin. Woody plants are more likely to contain tannins than herbaceous ones Mole , possibly because of a biochemical link to lignin synthesis. This may also explain the association of tannins with more primitive angiosperm groups and their relative rarity in advanced clades such as the Asteridae. A few families, such as the Araliaceae and Moraceae, appear to have relatively few members that synthesise them.

    Terpenoid glycosides, including cardiac glycosides, and saponins are among the most toxic of the terpenes found in plants. The modes of action are varied, but include an evidently unpleasant bitter taste Leaf form and physiology 77 and irritation of animal tissues. Tropical conifers are also very resinous. Essential oils are abundant in the Rutaceae. Ants are often highly aggressive to invaders of their territories, and myrmecophytic plants harness ant colonies to attack and deter potential herbivores.

    Many myrmecophytes provide domatia little houses for ants. These are usually pouch-like leaves or stipules, or hollow petioles or twigs. Both studies found EFNs to be particularly common in advanced angiosperm clades, notably Dilleniidae, Rosidae and Asteridae. Most of these provide domatia. Small ants may be better defenders against insect herbivores than large ones if reduced individual size translates into a higher density of defenders. This was hypothesised by Gaume et al.

    The holes in the stem are entrances cut by the ants to the hollow twig which acts as a domatium. Stature class Percentage of species with EFN no. It is not just animals that ants will attack if they come into contact with their host plant. Ants may also defend the host against other plants. Perhaps the most extreme example of this ant-mediated competition between plants has been reported in some neotropical spreading shrubs belonging to the Melastomataceae Morawetz et al.

    These clones are generally surrounded by clear space with no living plants. The ants Myrmelachista sp. They chew the shoot tips and main nerves of the leaves and spray a chemical from their abdomens into the wounds that they have made Morawetz et al. Plants treated in this way, including small trees, die rapidly. Very aggressive ant defenders could deter animals needed by the plant such as pollinators or seed-dispersers Thomas The apparent advantage to the ants of doing this is to maintain vegetative growth that allows more domatia and hence a bigger ant colony to develop.

    These domatia are believed to be important as sites in which mites can hide. Find out more about sending content to. To send content items to your Kindle, first ensure no-reply cambridge. Find out more about sending to your Kindle. Note you can select to send to either the free. Find out more about the Kindle Personal Document Service. Email your librarian or administrator to recommend adding this to your organisation's collection.

    Cambridge Tropical Biology Series. Download list of titles. About Cambridge Tropical Biology Series. Ashton , Harvard University , Stephen P. Hubbell , Princeton University , Daniel H. Janzen , Peter H. Tomlinson , Harvard University. Chapters 69 Books 4. Over 3 years 4. Cambridge University Press 4. Cambridge Tropical Biology Series 4.

    Actions for selected content:.