Limiting factors in desert ecosystem

Limiting factors in desert ecosystem

1. Arbab Ihsan Bs . ZOOLOGY BS.Zoology(7 th ) Section: A Enviromental Biology

2. Limiting Factors In Desert Ecosystem

3. Contents Define LF? Types of Limiting Factors Density Dependent Limiting factors Density Independent Limiting Factors Adaptations References

4. What Are Limiting Factors? “ Limiting factor is a resource or environmental condition that limits the size or growth of the population ”. Almost a definition of deserts, because deserts lack one or more essential ingredients for the survival of most kinds of plants and animals .

5. Types of Limiting Factors T wo types of limiting factors: Density-Dependent Limiting Factors Density-Independent Limiting Factors

6. Density- Dependent Limiting Factors “These are dependent on population density, such that their effects vary with respect to how dense the population is.” Competition Predation Food shortage Disease outbreak.

7. Competition Deserts are characterized by scarcity of water and vegetation . Competition for resources such as water and food . Competition for water: S ources of water in the Sonoran desert less S upport only a certain number of coyotes Limit size of population.

8. Competition For Food The Cactus Wren relies greatly on the Saguaro Cactus. Saguaro Cactus only provide resources for certain number of wrens. T he population density increase. Competition over cacti would increase. Only a certain density of Cactus Wren can be supported in an ecosystem.

9. Predation Unbalanced Predator-Prey Relationship: Snakes eat mice The mice don't get enough water or over heat and die T he snake population would decrease. S nakes don't get the food and die M ice population would increase .

10. Food S hortage Food is a limiting factor Very few animals live in the desert that must be able to adapt to it. F ew animals hard to find food Plants are scarce for herbivores due to the lack of water C arnivores and herbivores hard time finding food to survive in the desert.

11. Disease outbreak M ore dense a certain species population F aster and more likely a disease is spread. Example : T ortoises population in the Mojave deserts increases. T oo many tortoises will be living in this desert. There is a disease outbreak Affect a huge chunk of tortoise population B ring it down to sustainable levels

12. Density-Independent Limiting Factors “DILF are those that are not governed by population density, regardless of the density, all organisms are equally affected .” Precipitation Temperature Soil Water Sunlight Weather Conditions Natural Disasters

13. Precipitation The desert biome does receive rainfall, Rainfall as less than 10 inches to be precise. The scarce amount of water deserts receive in the form of precipitation Scarce water evaporates in hot deserts or frozen in cold deserts. F ew plants and animals are surviving in areas with such scant precipitation

14. Temperature: In deserts, the temperature is unbearably high or low The temperature increases or decreases drastically Effect population of specie Many species migrate to more favorable regions T emperature limiting both the number of species and their population.

15. Nutrient-Deficient Soil limiting factor is poor quality soil In hot deserts, with characteristic highly saline soil V egetation is dominated by succulent species, such as cacti . In cold deserts , vegetation cover is virtually absent T here is no soil to provide nutrients to the plants.

16. Water Water is a limiting factor in the desert Plants have a hard time growing limits the amount of plants as well as animals Some are adapted to survive Kangroo rat

17. Sunlight If lot of sunlight Plenty of energy for plants to harness and pass on to subsequent levels of the food chain. In hot deserts, sunlight is abundant, but other factors are not favorable. In polar deserts, they are in darkness for a significant part of the year.

18. Weather conditions Deserts are very hot Experience frequent sandstorms.  If there is a huge storm, as sand-storm A ll organisms will be affected .  Example: Desert may be very hot and cause camels to die due to dehydration. 

19. Natural disasters  “Natural disasters can cause great devastation to a single or many different populations”. When a natural disaster strikes the environment itself is changed . In deserts disasters such as dust storms, earthquakes, and volcanos strike fast and often.  Affect all population equally The Grand Canyon desert consists of all of these disasters.

20. Adaptations save water by not exposing themselves to hot temperatures. Insects, other invertebrates and vertebrates use underground burrows to shelter from temperatures . Some animals, escape the heat for months by aestivating in burrows. Most desert animals limit their above-ground activity in summer to twilight or evening hours . Desert sheep, goats insulating fur on the tops of their bodies have sparsely-covered abdomens and legs that radiate excess heat. Jackrabbits have long legs that carry them well above the heated ground large ears well-supplied with blood vessels. Many desert lizards possess nasal salt glands

21. References Reynolds, J.F., Virginia, R.A., Kemp, P.R., de Soyza , A.G. & Tremmel , D.C. (1999) Impact of drought on desert shrubs: effects of seasonality and degree of resource island development. Ecological Monographs, 69, 69–106. Richards, J.H. (1994) Physiological Limits of Plants in Desert Playa Environments. Land, Air, and Water Resources Paper. University of California, Davis. Ryel , R.J., Manwaring , J.H. (1996). Temporal dynamics of soil spatial heterogeneity in sage brush wheatgrass steppe during a growing season. Plant and Soil, 184, 299–309. Sah , R.N. & Miller, R.O. (1992) Spontaneous reaction for acid dissolution of biological tissues in closed vessels. Analytical Chemistry, 64, 230–233.