Chapter 6 Species Interactions and Community Ecology

1. Chapter 6Species Interactions and Community Ecology Exotic (non-native) species � a species not native to the local, regional, or continental ecosystem. Examples: Zebra Mussels, Kudzu, Privet, English Ivy, Asian Rice Eels, Asian Tiger Mosquitoes, Burmese and African Rock Pythons in the Everglades, Japanese Beetles,�

2. Exotic species problems: Competition for native species - including displacement, predation on native species, lack of predators to control populations, may bring unfamiliar diseases, more aggressive reproduction, environmental disruptions,� Sometimes the local ecosystem can accommodate and assimilate the invader without major problems. Exotics may become a new food source for native predators (blue jays eating Japanese beetles) and exotics may be susceptible to native diseases also.

3. Species Interactions Predation * Parasitism * Competition Symbiosis (Mutualism) * Commensalism Predation � one organism consuming another. Parasitism � 1) Parasite is usually smaller than host; 2) Remains closely associated with and may weaken host. 3) Rarely kills host

4. Competition � Niche overlap, habitat overlap, resource partitioning, migration, starvation. Mutualism � Symbiosis, perhaps mutual exploitation, both organisms benefit. Example � ants & aphids, Lichens (algae & fungi), coral polyps & algae. Commensalism � One organism benefits, the other is not hurt (mistletoe, Resurrection ferns, other epiphytes).

6. Habitat � where an organism lives. Niche � role an organism plays within its ecosystem. Generalist species � organisms with broad niches, i.e., they are adaptable to changes. Examples: humans, coyotes, raccoons, rats, cockroaches, possums. Specialist species � organisms with narrow niches, i.e., they are not well adapted to changes. Examples: Giant pandas, Koalas, other endangered species.

7. A species' niche includes- The range of tolerance for different conditions; The types of resources used (foods eaten); Its interactions with abiotic and biotic components of its ecosystems; The role it plays in its ecosystem's flow of energy, i.e., which trophic level does it belong to? Niche overlap � competition for food. Habitat overlap � competition for living space.

8. Specialist Species have the advantage during stable environmental conditions, as there is less competition for their specialized foods, habitat, etc. Koalas, Giant Pandas,� Generalist Species have the advantage during unstable environmental conditions, as they are adaptable to changes and can deal with competition. Humans, Coyotes, Roaches, Rats,�

9. When a species undergoes a habit change that brings it into direct competition for habitat and/or resources with another species, over time one species will dominate and the other will have to 1) Migrate; 2) Become extinct; 3) Change its behavior to minimize competition (Resource partitioning). With some animals, e.g., Giant Pandas, scientists may not know why the resource partitioning occurred.

11. Succession is the process of nature�s recovery after a disturbance. Primary Succession � follows a major change, withdrawal of a glacier, total deforestation, etc.. Secondary Succession � follows less severe changes, e.g., reclamation of an abandoned cow pasture or logging road, or a forest floor after a major fire. Resilience is a measure of how quickly an ecosystem recovers from a disturbance.

12. Reclamation of an old parking lot (or an old lava flow) � Primary Succession.

13. Pioneer Community on a fresh outcrop may begin with Rock lichens, followed by mosses & drought resistant ferns.

14. Recovery of forest floor after 1988 Yellowstone forest fires � Secondary Succession.

16. Success of Secondary Succession depends on thickness and quality of O and A layers of soil. Relates to temperature and moisture availability.

20. Major Biomes Tundra � Northern Hemisphere � High lati-tude (generally north of 600 N), no South-ern Hemisphere landmass at correspond-ing southern latitudes. Long, harsh winters, short summers (with long daylight hours) = thin, nutrient-poor, immature soils, slow nutrient cycling. Usually underlain by permafrost that inhibits deep root growth needed for woody species. Low species diversity & low primary productivity. Most plants are less than 12 inches high.

21. Taiga (boreal forests) � Adjacent to Tundra in Northern Hemisphere � High Middle Latitudes (generally 450 to 600 N). No southern analogs. Coniferous forests with thin, acidic O and A layers (slow nutrient cycling due to moisture being �locked up� in ice & a waxy nature of conifer needles). Conifers have the benefits of less surface area on �leaves� = less loss of heat. Retained needles are needed for short growing seasons. Rich timber growth is harvested for construction needs, forests need management to recover.

22. Tropical Rainforests are characterized by rapid nutrient cycling, thin O and A layer, highly leached subsoil. Poor resiliency after large-scale disturbances. Characterized by Evergreen Broadleaf trees and plants Tropical Moist Forests � include High altitude cloud forests � persistent clouds and mist & Tropical Broad-Leaf Evergreen (rainforest) � little variation in moisture and temperature, almost daily convection storms. Rich in timber resources, subjected to harvest pressures.

23. Tropical Seasonal Forests � in areas with distinct wet and dry seasons. Includes semi-evergreen/ partly deciduous forests with open woodlands and grassy savannas. Attractive to human habitation & agriculture. The Serengeti Plain of Africa is a good example of this biome (ecosystem).

24. Temperate Deciduous Forest Biome � Seasonal changes, cool enough for shedding of leaves by broadleaf trees & plants. Early secondary succession (locally) � Loblolly Pine, Sweetgum, Tulip Poplar, blackberries. Mature stage - Oak, Maple, Hickory, Poplar, Sycamore, Beech. Good O and A soil, good rainfall, good biodiversity, high resiliency. May have 3 or 4 layers of vegetation.

26. Enough precipitation to allow growth of grasses. Sporadic rainfall/frequent fires prevent large stands of trees. Cold winters, hot and dry summers Favorable for cereal grain production. Good roots/ O and A soil = high resiliency.

27. Grassland Biome (OK, KS, Eastern CO, Dakotas, NE, Eastern Wyoming) problems: Dry enough to be susceptible to wind erosion of O and A soil horizons Short growing season - Slow nutrient cycling May lack surface waters for farming Overuse of groundwater possible Salinization of farmland possible

28. Mediterranean/Chaparral/Thorn Scrub � thickets of evergreen shrubs and small trees, characterized by hot, dry summers & cool, moist winters. Includes California Scrub thickets & parts of the Basin & Range province. Desert Biomes �Caused� by 1) Climatic conditions (high pressure zones near 300 N latitude and 300 S latitude; and 2) Rain Shadow Effect. Various deserts � 1) Tropical; 2) Temperate; 3) High Altitude; 4) Tundra (subpolar).

29. Uplift of Air Masses by Mountains � Orographic Effect on Windward side, Rain Shadow Effect on Leeward side.

30. Olympic Peninsula and coastal WA, OR, and BC rainfall due to Orographic Effect. Prevailing winds come from the Pacific Ocean, keeps temperatures mild even in winter.

31. 4 North American Temperate Deserts: Chihuahuan - Great Basin � Sonoran - Mojave Desert concepts - Conservation of water, heat survival most important Small, nocturnal, water efficient animals Small leaves on plants Shallow, broad root system or deep root system Cacti store water in pulpy tissues Annuals store biomass in seeds

32. Desert Problems � Low diversity, Poor O and A soil, slow plant growth, poor water resources, slow nutrient cycling

33. Due to low rainfall (about 4 inches/year), nutrient cycling is slow � Low Resiliency, fragile ecosystem.

34. In the intense Sonoran Desert sun, Saguaros need some shade to sprout�

35. Mountains � Islands of diversity - various orientations of valleys, elevation changes help provide for sub- and micro-biomes. �Orographic lifting� increases rainfall, valleys help entrap moisture. Because of steeper slopes, when vegetation is disturbed, the soil is more susceptible to erosion. McKittrick Canyon, Texas � relict flora, protected in SE facing valley

36. Savannah � Tropical Grasslands Broad, flat grasslands with isolated clumps of low-growing trees. Important because of the rich species diversity of large hoofed herbivores, e.g., zebras, giraffe, wildebeests,� and large carnivores, e.g., lions, leopards, hyenas, cheetahs. Though present in other areas, the Savanna biome is most prominent in Africa, where it is being threatened by conversion to grazing for cattle & other domesticated animals. Other human encroachments also threaten this biome and trees are being cut for firewood.