Global Change Ecology Lecture Notes

These flashcards cover key concepts and facts related to global change ecology discussed in the lecture notes.

What kind of effect does elevated CO2 have on photosynthesis?

Elevated CO2 increases the photosynthetic rate, with a typical average increase of 44% when CO2 concentration is doubled.

What is the fertilization effect in the context of CO2?

The fertilization effect refers to the increased growth and photosynthetic rate of plants due to higher CO2 concentrations.

What limits the fertilization effect of elevated CO2?

Low soil nutrient levels limit the fertilization effect; if soil is poor, plants will not exhibit significant growth even with elevated CO2.

Why are C3 plants more responsive to elevated CO2 compared to C4 plants?

C3 plants have a higher CO2 saturation point, allowing them to benefit more from increased CO2 levels than C4 plants.

How do legumes respond to elevated CO2 compared to non-legumes?

Legumes respond more positively to elevated CO2 levels due to their symbiotic relationship with nitrogen-fixing bacteria, which provides them with a consistent nutrient supply.

What happens to respiration rates in plants grown at elevated CO2?

Respiration rates can increase due to higher energy demands from increased growth and the availability of more carbohydrates as substrates.

What are the two types of plant respiration?

Growth respiration, associated with the production of new tissues, and maintenance respiration, associated with maintaining existing tissues.

What is the impact of elevated CO2 on leaf nitrogen levels?

Leaf nitrogen levels typically decrease under elevated CO2 conditions, impacting the protein content of plants.

What is water use efficiency, and how is it affected by elevated CO2?

Water use efficiency measures how effectively plants use water to produce biomass; it tends to increase under elevated CO2 due to stomatal regulation.

What is the predicted impact of increased CO2 on crop yield?

Increased CO2 is expected to lead to larger crop yields, although the quality of the crops, particularly in protein content, may decline.

What correlation exists between CO2 concentration and global temperature?

There is a positive correlation; when CO2 levels are high, temperatures tend to be high, and vice versa.

What happens to carbon cycling when forests reach CO2 saturation?

When CO2 saturation is reached, forests may shift from being carbon sinks to carbon sources, releasing more CO2 into the atmosphere.

How is the relationship between CO2 concentration and global temperature relevant to wildlife?

Lower protein concentrations in plants due to elevated CO2 can affect animal growth and development, impacting the entire ecosystem.

What kind of effect does elevated CO2 have on photosynthesis?

Elevated CO2 increases the photosynthetic rate, with a typical average increase of 44% when CO2 concentration is doubled.

What is the fertilization effect in the context of CO2?

The fertilization effect refers to the increased growth and photosynthetic rate of plants due to higher CO2 concentrations.

What limits the fertilization effect of elevated CO2?

Low soil nutrient levels limit the fertilization effect; if soil is poor, plants will not exhibit significant growth even with elevated CO2.

Why are C3 plants more responsive to elevated CO2 compared to C4 plants?

C3 plants have a higher CO2 saturation point, allowing them to benefit more from increased CO2 levels than C4 plants.

How do legumes respond to elevated CO2 compared to non-legumes?

Legumes respond more positively to elevated CO2 levels due to their symbiotic relationship with nitrogen-fixing bacteria, which provides them with a consistent nutrient supply.

What happens to respiration rates in plants grown at elevated CO2?

Respiration rates can increase due to higher energy demands from increased growth and the availability of more carbohydrates as substrates.

What are the two types of plant respiration?

Growth respiration, associated with the production of new tissues, and maintenance respiration, associated with maintaining existing tissues.

What is the impact of elevated CO2 on leaf nitrogen levels?

Leaf nitrogen levels typically decrease under elevated CO2 conditions, impacting the protein content of plants.

What is water use efficiency, and how is it affected by elevated CO2?

Water use efficiency measures how effectively plants use water to produce biomass; it tends to increase under elevated CO2 due to stomatal regulation.

What is the predicted impact of increased CO2 on crop yield?

Increased CO2 is expected to lead to larger crop yields, although the quality of the crops, particularly in protein content, may decline.

What correlation exists between CO2 concentration and global temperature?

There is a positive correlation; when CO2 levels are high, temperatures tend to be high, and vice versa.

What happens to carbon cycling when forests reach CO2 saturation?

When CO2 saturation is reached, forests may shift from being carbon sinks to carbon sources, releasing more CO2 into the atmosphere.

How is the relationship between CO2 concentration and global temperature relevant to wildlife?

Lower protein concentrations in plants due to elevated CO2 can affect animal growth and development, impacting the entire ecosystem.

What is the primary mechanism by which elevated CO2 increases photosynthetic rate?

Elevated CO2 reduces photorespiration by increasing the CO2 to O2 ratio at the active site of the RuBisCO enzyme, optimizing carbon fixation.

How do C3 plants initially fix carbon?

C3 plants fix CO2 directly into a three-carbon compound (3-PGA) using the enzyme RuBisCO in the mesophyll cells.

How do C4 plants initially fix carbon?

C4 plants first fix CO2 into a four-carbon compound using PEP carboxylase in mesophyll cells, then transport it to bundle sheath cells where CO2 is released for the Calvin cycle.

What is the main reason for decreased leaf nitrogen concentration under elevated CO2?

The 'dilution effect,' where increased carbohydrate production (biomass) outpaces the uptake or assimilation of nitrogen, leading to a lower concentration of nitrogen per unit of plant tissue.

How does stomatal regulation contribute to increased water use efficiency under elevated CO2?

Under elevated CO2, plants can partially close their stomata, which reduces water loss through transpiration while still allowing sufficient CO2 uptake for photosynthesis, thus conserving water.