Decomposition Flashcards
Why do decomposer microbes secrete enzymes into the soil rather than breaking down dead organic matter inside their bodies?
Microbes secrete enzymes into the surrounding soil/environment to break down dead organic matter instead of inside their bodies because that way the CO2 they release is available to other microbes and plants.
Why do you see a different shape of the temperature-soil respiration relationship measured in the lab incubations of soils from one site, versus across a spatial gradient in soils?
The relationship between temp and respiration in the lab isn’t the same as their relationship across space because of differences in species composition, environmental conditions and scale.
How does temperature influence decomposition rates directly, and indirectly (via influences on soil moisture and nutrients)?
Warmer temperatures can directly dry out soil depending on prior conditions, if the soil is already dry then more drying will reduce microbial activity. However water logged soil/anoxic drying can increase microbial activity. Indirect temperature effects such as, high temps may increase nutrient availability through weathering and decomposition. Warm and moist conditions have high NPP and are more easily decomposed,
you find that fungi in your forest soils have a C:N of 20:1, assuming a 50% growth efficiency, they will mineralize N when their substrate is_____ than the critical C:N ratio of _____?
In your own words, define complementary resource use, and explain why this concept is important for understanding the relationship between species richness and ecosystem functions such as productivity.
Complementary resource use is when each species uses different types of resources, rooting depths or seasons of absorption. This is important for understanding the relationship between species richness and ecosystem functions because it explains the ways diverse species coexist and contribute to ecosystem processes without too much competition for limited resources.
In addition to complementary resource use, what are two additional mechanisms that could explain a positive relationship between species richness and productivity?
The two additional mechanisms include Selection effect and the influence of other trophic levels. Selection effect is when the likelihood of having a highly productive species increases with plot richness. The other mechanism is the influence of other trophic levels which can be measured by the amount of pathogen load. When there is a high pathogen load those plants spend a lot of their energy fighting pathogens rather than allocating their carbon energy to growth.
What are the three mechanisms discussed in lecture by which species diversity influences ecosystem stability in a temporally variable environment? How are they distinct?
a)Redundancy- having diversity within function groups, it can buffer ecosystems functioning with declining biodiversity.
b)Portfolio effect- with increasing diversity, increasing probability of having species that can survive a severe event.
c)Negative covariance- due to tradeoffs among species, results in increasing stability.
Give an example from the book or from a lecture showing how a plant trait influences ecosystem function.
An example of how a plant trait influences ecosystem function is root length, root depth, and root activity. They influence total nutrient absorption by vegetation mainly when supply rate exceeds plant nutrient requirements.
