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Describe the grassland community.
Native bunchgrasses (indicator); marsh habitiat, etc. Also Valley Oaks. Perennial native grasses. Fibrous root system for adaptations; areas have very rich topsoil.
What is a gall?
Abnormal growth/swelling in a plant. Can be induced by infection from bacteria or fungi, or by attack from mites, nematodes or insects. Can form on any of a plant’s organs. Some indiciated a type of disease, while others cause no harm to host. Some are beneficial (nodules in the legume family fix N2). Many galls are caused by cynipid wasps that lay eggs in plant tissues. The CA gall-fly produces large-diameter oak apples and many other species associate with the gall.
Describe the riparian wilderness community.
River-side community, indication that water is nearby.
Describe the foothill woodland community
Higher elevation that chaparral community, oaks/pines, more legit soil than chaparral
Mixed coniferous forest
Highest elevation, still snowy/slushy. Huge trees, with leaves high from ground for fire control.
- Study of interactions between organisms and their environment
- Environment includes biotic and abiotic factors
Define ecosystem, population, community
- Ecosystem: A biological community and the abiotic factors with which they interact. The basic unit of ecology.
- Population: group of species within the area of interest
- Community: all populations in a given area
Hierarchy of ecology terms.
Ecosphere -> Ecosystem -> Community -> Population -> Individual organism
What are the two fundamental processes that must occur in an ecosystem w/ details?
- Energy flow: one-way flow of energy through components of the ecosystem. Requires a continuous outside source of energy due to energy transfer inefficiency (energy released as heat at each transfer).
- Chemical cycling: chemical elements cycle from biotic to abiotic components of the ecoysystem (S,P,O,N,C,H)
- Abiotic reservoir: storage area for chemical when not part of biotic components
Trophic levels of an ecosystem + details
- Typically limited to 3-5 steps due to energy transfer inefficiency (less than 20% transfer between trophic levels)
- Producers -> consumers (primary -> quaternary) -> Detritovores
Food chain vs. Food web
- Food chain: revelas the sequence of energy and nutrient transfers among different trophic levels
- Food web: Food chains interconnect to form complex food webs
Basic water cycle
Body of h2o –(evaporation)-> clouds –(wind)-> clouds move -> clouds raise as land raises –(clouds cool)-> H20 released as rain or slow –(melt)-> streams -> rivers -> bay -> ocean
Basic carbon cycle
CO2 –(photosynthesis)-> plant -> glucose -> animal –(respiration)-> CO2
Basic nitrogen cycle
- Used in proteins, DNA, etc
- Plants take in N2 by taking in nitrates
- Most of this comes from the nitrification of ammonium released as a byproduct of decomposition by nitrifying bacteria
Plants abs nitrates from soil -> convert to NH3 -> amino acid synthesis -> decomposition -> ammonification (by soil bacteria) -> nitrification (by soil bacteria) -> used by plants or denitrification releases N2 back into atmosphere
Excessive nourishment of aquatic ecosystems. Algae have excessive growth, die, and dramatically increase the rate of decomposition. O2 levels may become next to zero, causing species depletion.
Define biological magnification
Toxic persistant substances become concentrated in higher levels of the food chain through accumulation in the fatty tissues
Interactions amongst species
- Competition: organisms competing for a similar limited resource (interspecific or intraspecific) – harmful to both species
- Mutualism: beneficial to both species
- Commensalism: beneficial to one species, other unaffected
- Parasitism: beneficial to one species, harmful to the other
What is the principle of competitive exclusion?
- No two species with similar resource usage can occupy the same habitat
- In the lab one is completitively excluded
- In nature resource partitioning occurs (natural selection favors reduced competition)
The inhibition of one species of plant by chemicals produced by another plant (chamise)
What is a phytoalexin? Tannin? Resin?
- Phytoalexins: natural plant compound that acts as an antibiotic in response to a bacterial or fungal infection (eg H2O2)
- Tannins/resins offer static protection from infection
- Types of succession
- After a disturbance a pioneer speces arises, usually with very different features than the previous members of the mature community.
- Primary succession: soil formation occurs in a previously desolate area (can’t be studied in real time), usually through the aid of a pioneer species. Continues until a climax community appears (a somewhat stable assemblage of plants and animals).
- Secondary succession: Occurs within an area already covered with climax species (soil already present). Faster pace than primary succession).
Patterns of dispersion in population ecology
- Clumping: organisms aggregated a specific resource
- Uniform: Uniform spacing often as a result of competition for resources
- Random: Individuals do not interact strongly with eachother (very rare in nature)
Population growth dynamics
- r = (B-D)/N
- r = growth rate, B = births, D = deaths, N = number of individuals
- If r is + population is expanding
- If r is – population is declining
- If r = 0 population is stable at RLF (replacement level fertility)
- Rmax=natural maximum rate of growth (highest that CAN be expressed), has an exponential (J-shaped) curve
- K = carrying capacity (natural size of population with stable growth rate) – affected by environmental resistance
Two types of population growth rates (graph)
- S shaped: pronounced stable growth rate
- Cyclic: Periods of J shaped growth followed by periods below K
- Many organisms are a blend of these two rates
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