Exam 2 Review: Forest Ecology PDF
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This document appears to be notes, rather than a past paper. It details various aspects of forest ecology, including ecological processes like conspecific negative density, the Janzen-Connell Hypothesis, the green world hypothesis, and trophic cascades. The document also covers ecosystem engineers and symbiotic relationships. It's likely a comprehensive set of notes for a forest ecology course.
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**[EXAM 2 REVIEW:]** Need to read the nitrogen cycling section of the book chapter. Ch. 18 Ton of points on the exam based on Tuesday from thanksgiving lecture. **[Conspecific Negative Density:]** an ecological process where a species\' growth, survival, and recruitment are negatively impacted by...
**[EXAM 2 REVIEW:]** Need to read the nitrogen cycling section of the book chapter. Ch. 18 Ton of points on the exam based on Tuesday from thanksgiving lecture. **[Conspecific Negative Density:]** an ecological process where a species\' growth, survival, and recruitment are negatively impacted by its own local population density. CNDD can help maintain species diversity in forest communities by allowing other species to replace adults of a common species. - - **[Janzen-Connell Hypothesis:]** host-specific natural enemies are concentrated where their host plant species occur at high densities [Explanation:] [Prediction:] Vertebrate Herbivores & Predations: **[Green World Hypothesis:]** The world stays green due to predators that kill and eat, regulating the population of consumers. (indirect effects) The green world hypothesis is based on the idea that a system of checks and balances is required to allow for the flourishing of flora in various ecosystems. Predators help regulate herbivore populations, limiting the amount of vegetation that is consumed. This is a radical concept because, before the green world hypothesis, no one thought predators played a role in regulating ecosystems. **[Trophic Cascades:]** The phenomenon of regulation of plants/producers by apex predators. Taking away/adding predators to a system results in a huge change. When a predator reduces the number of prey or changes their behavior, it allows the next level of the food chain to increase in number. This can then trickle down to affect the density or behavior of the prey\'s prey. **[Ecosystem Engineer:]** Animals that create, modify, or maintain habitats. Typically has some large effect on an ecosystem or a process. Ie Beavers, coral, termites. **[Symbiosis/Symbiotic relationship:]** Long term, relatively stable and very close relationship. An interaction between two different organisms living in close physical association. Ex. Lichen, **[Muatilism:]** Symbiosis with advantage to both species. Ex. Bees **[Mycorrhizal:]** Myco = fungus, rrhizal = root. a symbiotic relationship between a plant and a fungus that is beneficial to both organisms: [Definition:] [Benefits:] **[Endomycorrhizae:]** A widespread and important root symbiont found in agricultural and forest soils. They are found on most hardwood families and some conifer tree species. **[Ectomycorrhiza:]** (EcM) (EDIBLE) A type of mycorrhiza that improves the host plant\'s nitrogen nutrition. **[Common mycorrhizal network:]** The situation where you have at least two different plants whose root systems are connected and become integrated by the mycorrhizal fungus. T/F: Root nodules on an alder tree is where ectomycorrhizal fungi fix nitrogen. False: It is a bacteria called Frankea. **[Ectomycorrhizae or Mycorrhizal are NOT at all the same as nitrogen fixing bacteria (*Frankea*) ]** - Most nitrogen stocks in an ecosystem, most is tied up in organic matter, decay of organic matter releases that into the soil which is then able to be uptook by existing plants. 5-8% of global nitrogen budget is coming from lightning **[Primary succession:]** No measurable trace of an established ecosystem there, glacial retreat, new lava flow, development of plant communities on that surface. **[Secondary Succession:]** Development of plant communities after a disturbance, wildfire, landslide. **[Depolymerization:]** the process of breaking down polymers into smaller molecules, called monomers or co-monomers **[Fixation:]** Adding new nitrogen coming from the atmosphere Do soil microbes compete with plants for uptake of soil nutrients? Yes. Definitely. **[Immobilization:]** the process where microorganisms in the soil convert inorganic nutrients (like nitrogen) into organic forms, making them temporarily unavailable to plants by incorporating them into their own biomass, essentially \"locking up\" the nutrient and taking it out of the readily available pool for plant uptake; it is the opposite of mineralization, where organic matter is broken down back into inorganic forms. **[Mineralization]**: a biological process that converts organic nutrients into inorganic forms that plants can use: [Explanation] Mineralization occurs when microbes break down organic materials like manure, plant residue, and soil organic matter. This process releases nutrients like nitrogen, phosphorus, and sulfur in forms that plants can use. **[Key Piece:]** One individual piece that has a huge effect, log in the river. **[Keystone Species:]** A species that has a disproportionate effect relative to its biomass/abundance. **[Throughfall:]** When precipitation moves through the canopy and collects nutrients and organic material on the way down. **[Stem Flow:]** Same thing but some fraction will flow down through the stem. Leeching & Washing recycles nutrients. **[Treeline:]** Temperature, soil/edaphic controls, winter damage(wind/ice) **[Krumholz:]** Its not species specific, just so stressful above the boundary layer the only shoots that can survive have to adapt low. As things get more stressful, the idea is it\'s better to be closer to other plants than further away, vs when it\'s not as stressful you are competing more. **CAUSES OF ALPINE TREELINE:** Establishment and growth of trees in extreme environments What determines the limits of forests? - - - [Alpine treeline ecotone:] Transitional zone between forest lines. Forest line → Treeline → Krummholz line Dispersal → Germination→ Establishment→ Growth Multiple controls at treelines acting on both growth and establishment of forests. But the strength and impact varies by location/species **Stress Vs Disturbance:** Stress = External constraints on primary productivity Disturbance = any relatively discrete event in time that disrupts structure, changes resources, substrate availability, or physical environment **Growth Vs Establishment:** Establishment = tree reaches some size in which is related to increased probability of survival to maturity Growth = Accumulation of biomass, ultimately via cell division **Adiabatic cooling:** atmospheric pressure decreases w/ increasing altitude, leading to reduction in air temp. Higher == Cooler!