2011 Biology Capstone: Sydney Wendt



This biome generally does not experience much rainfall. These plants are deciduous and drop their leaves during the driest months of the year to conserve water. This biome has high temperatures throughout the year. They are located near tropical rainforests in Africa, South and Central America, Mexico, India, Australia, and tropical islands.

 Precipitation and Temperature: 
Biotic Factors: 
  • Archaebacteria: Crenarchaeota
  •  Eubacteria: Beijerinckii, Klebsella, Azotobacter
  •  Protista: Amoeba, Paramecium
  •  Fungi: Mold, Mushrooms, Lichens
  •  Plantae: Deciduous shrubs, Acacias, Deciduous trees, Legumes, orchids, bromeliads
  •  Animalia: Tasmanian Devil, Lizards, Coyotes,  Foxes, Badger, Bobcat, Mountain lion, Monkeys, Tiger
 Abiotic Factors:
  •  Elevation: 200-1000 meters above sea level
  • Topography: some rivers and streams, level plains
  • Average yearly wind speed:14mph
  • Soil Conditions: Nutrient rich alluvial soils that are moist and dark in color. Soils are subject to erosion.

Food Chains and Web:

  •  Sun àGrassàSquirrelàPine MartenàBobcatàLichen
  • SunàShrubsàMouseàSnakeàHawkàMaggots
  • SunàFruitàSmall BirdàWestern Whiptail LizardàCoyoteàMold


Water Cycle:

 In the tropical dry forest transpiration occurs when water is evaporated from the stoma under the leaves. When it precipitates it is intercepted by the canopy and many of it does not hit the ground because of the many trees. Some water makes it to the ground and soaks in the soil. The roots then take up the nutrients from the soil and the cycle begins again.

Carbon Cycle:

 In the tropical dry forest the trees perform photosynthesis to make their own energy. Then animals feed off of the plants and breathe out CO2. The carbon then goes back into the atmosphere. Cellular respiration occurs from both plants and animals. Also when the animals die and decompose the carbon is eventually brought into the soil.

Nitrogen Cycle:

 After nitrogen is fixed by bacteria plants take it up through the soil by assimilation. When the plants eventually die the nitrogen is released into the soil and water. Also when animals eat the plants and they die or excrete the nitrogen is released.

Phosphorous Cycle:

 After it rains on rocks in the forest the phosphates are removed and distributed in the soil. Plants take nutrients up from the soil, including phosphates, and are eaten by herbivores and then carnivores. The phosphate is then absorbed into the animals’ bodies and eventually returned to the soil by excretion and decomposition.

Symbiotic Relationships:

Mutualism- In the tropical dry forest ants chew a small hole into the thorn of the plant acacias. The ants use this as their home and are provided with nectar secreted from the plant. The plants receive protection because the ants will sting and bite herbivores. This relationship is seen as mutualism because both the acacia and the ants benefit.

Commensalism-  Plants such as cactus and orchids are abundant in the tropical dry forests. Epiphytes are plants that live perched on sturdier plants. They do not take nutrients or water away from their host, they just benefit from being more exposed to sunlight. This relationship is seen as commensalism because the plants are not hurt or harmed, but the epiphytes benefit.

Parasitism- Sycamore lace bugs feed on sycamore trees in the deciduous forest. When many sycamore lace bugs are feeding off of the same tree it can cause the tree to defoliate. After some time the trees will die from the bugs. This relationship is seen as parasitism because the sycamore lace bugs benefit because they can eat food, but the sycamore trees are harmed because they will eventually die.


After an extreme drought occurred in the tropical dry forest all of the trees and plants would be dead. They would not have enough water to survive and would end up dying. If all the trees and plants were dead the herbivores in this biome would not have anything to feed off of. They would eventually die too, leaving no food for the carnivores and omnivores. Eventually everything in this biome would die from the effects of a drought.

Secondary succession would occur because there would still be soil in the environment. Grasses would start to grow back. Then small shrubs and flowering plants would grow. Next, insects would come populate the area. Small trees such as saplings would then begin to grow. Animals would then come such as rodents, rabbits, foxes, and birds. Soon mature trees would grow and the tropical dry forest will have grown back. The animal population would probably be different after secondary succession because different species of animals would come back to populate the area.