BIOL 420 1st Edition Lecture 19Tropical Rain ForestsGeography and Location- Equatorial regionsClimate- Always warm to hot through the entire year, relatively constant temperatures, never below freezing. - Rain fall is plentiful and constant – you can see the lush growth you get from tropical rain forests. - 50% of the world’s organisms live in these forests - No seasonal variation, growth throughout the year- Most precipitation of any biome- Other plants and animals tend to be the greatest limiting factor (competition)Soil Quality- Relatively poor  little top soil, usually the soil is relatively than to other habitats, poor in minerals because most of it is in the plant.- Growth is most favorable, immediately recycled in the flowering plant- Low in nutrients because of high productivity- Low in humus because of rapid decomposition and recycling of nutrients, all nutrients tied up in standing vegetation due to the wet, decomposition happens fast and you don’t find the litter growing up. - Relatively thin topsoils Precipitation and Water Availability- Greatest precipitation of any biome- Fires rare because of lack of combustible fuel (litter) doesn’t accumulate Species diversity (richness)- More than 50% of Earth’s organisms live in tropical rain forest with perhaps 5-30 million species still undescribed.- Even higher percentage of world’s plants and certain animal groups (insects, fungi, amphibians, birds, reptiles) perhaps 60-80%.Characteristic PlantsPlant Adaptations- Trees – dense canopy, generally at least four layers to the rain forest, tree species that grow above canopy, 2 tiers of trees in canopy, shade tolerant understory. Very dense growth of trees. (ex. Ferns, orchids, )o Canopy: very dense because the growth is dense. The layer consists of 2 layers. Speices are adataped in growing in the tiers, the trees grown below are shade toleranceo Emergent: grow above the canopy. o Understory: all of the tress have to be shade tolerant, immature versions of themselveso Ground cover its pretty open and walk freelyo Immature: the bottom –o Floor: ferns, mosses, extreme low light conditions. Light will be one of the limiting factors.- There may be several hundred tree species within a few acres- Most edible leaf biomass in rainforests is in canopy, herbivores and predators that eat them are sparse on forest floor- Decay and insect resistant wood – examples Cinchona (quinine) Cinnamon (bark)- Buttressing – resists wind – soil is much loser, it’s tall and skinny that is being knocked over the wind. - When the tree falls can have tremindious effects but the whole area (vines) are very common, and grow from one tree to another. The vines are ting each other together, plants that are outcompeted. - Shade tolerant speciesFerns and mosses- Tree fall – major agent of change, opens canopy, light reaches forest floor- Epiphytes (adpations – grow on the body of other plants but do not harm them just using the tree as support so they could compete with light)Orchids (Orchidaceae) – characteristics.Largest family on earth. Highly evolved, monocot, a lot of orchids the sepals and petals look the same, have a 3rd petal that is differentiated (the lip – labellum) that draws the insects in. the landing pad and requires the insect to walk into it and brush against the anthers. The stamens and pistils are weird, there are usually one of them and fuse to create a column. The anthers fuse to a pollinia, the entire structure when the insect visits the plant, the insect ends up taking the anther and giving it to another orchid. The column (fused anther or stamen or pistil), the pollinia (anther) which attaches to the insect (mouth part of the mouth), it then transports the pollen to another plant. Bromeliads (Bromeliaceae) – characteristics. About 3000 species, monocots, trees are the dicots, Lianas – vines 90% of world’s vines are endemic to tropical rain forest (Ficus) - “strangler figs”Orchids (Orchidaceae) – characteristics- Monocots, largest family of flowering plants, 24,000 species- Individual species rarely very abundant- Most are tropical (only 140 native to US and Canada)- Bilateral symmetry, beautiful forms and shapes- 3 carpals fuse to form pistil (gynoecium) – may have thousands of tine ovules (eventuallythousands of tiny seeds)- Usually only one stamen- Column – in orchids formed by the fusion of the stamen and pistil- Pollinium – in orchids the entire contents of the anther is held together and dispersed as a unit (insects disperse the entire pollinium)- Petals (3) usually modified into a showy “lip” (landing pad) and two wings- Sepals (3) often colored and look like petals- Orchid flowers can be large (15 inches in diameter) or as small as a pinhead- Several genera lack chlorophyll and survive as myco-heterotrophs (roots symbiotic with fungi)- Two Australian orchids grow underground (pollinated by flies)- Cultivated commercially, more than 60,000 registered hybrids- Examples of orchidsBee orchid – no nectar, but labellum imitates female bee (Europe); attracts other bees as pollinators. A pheromone that smells like a beeBlack orchid – national flower of Belize; black color is actually brown or purple; much effort among orchid breeders to breed a “true” black orchid. The worlds darkest orchid. Anthocynadin so its more purple,Boat orchid (Asia): the lip and column look like a boat with the sepals and petals look thesameUndergound orchid (Australia) Rhizanthella, parasitic mycorrhiza fungi symbiotic with roots of the broom brush; only 50 plants are known, location protected – underground orchid, extremely rare, grows entirely underground, it parasitizes the root that grows in that area. South Carolina orchids – 50 species; (Pogonia orchid and Yellow fringeless orchid). Most are terrestrial and not epiphytic. Cultivated orchids – 60,000 registered hybrids. Vanilla: Bromeliads (Bromeliaceae) – characteristics- 3,000 species; monocots, all but one species native to the tropical areas of Central and South America); our “Spanish moss” Tillandsea, the exception- Many bromeliads are short-stemmed epiphytes, others are terrestrial, grow on ground- Leaves of bromeliads arranged spirally in a “rosette”- Petals and sepals usually differentiated- A lot of house plants because it can adapt to low light conditions.- Bromeliad pools: traps water to reproduce- Many tropical bromeliads trap pools of water