NR501 UNIT 4 - LATEST UPDATE QUESTIONS
WITH CORRECT ANSWERS
How are soils impacted by climate change and how do they impact climate change? - CORRECT
ANSWER -Soil moisture and temperature influence greenhouse gas fluxes from the soil.
Approximately 20% of soil carbon is lost due to warming. Elevated precipitation generally
increases plant productivity and carbon inputs to soils; drought typically reduces plant growth
and carbon inputs. Drought limits soil respiration, whereas increased precipitation stimulates
respiration. Soil freezing and thawing increase soil carbon and nutrient availability due to
microbial and root cell lysis and/or soil aggregate disruption.
How is climate expected to change in the Northeastern U.S.? - CORRECT ANSWER -The
Northeastern U.S. is expected to have a temperature increase of 1.1 degrees C. By 2070, the
climate will resemble South Carolina or Florida. Spring time will arrive three weeks earlier and
summer will be three weeks longer. We'll receive more precipitation in the winter and more
drought in the summer. Less snow will fall and they'll be an increase in extreme weather events.
How do soil organisms release CO2 and other trace gases to the atmosphere (or in some cases,
take up greenhouse gases from the atmosphere)? - CORRECT ANSWER -Soil microbes uptake C
and then respire CO2. They are highly abundant in the soil, and their activity at the ecosystem
level affects a global scale. Soils also release greenhouse gases such as methane, found in
wetland environments (oxic soils), and nitrous oxide, produced through nitrification and
denitrification.
How is soil respiration measured in both the field and lab? - CORRECT ANSWER -In the field, the
static chamber method or auto chamber method are used to determine soil respiration. In the
static chamber method, a pbc collar is pushed into the soil about 3-5 cm. The collar is lidded
and a sample is taken up with a syringe and a gas chromatograph analyzes it. The auto-chamber
method is set up to open and close on their own every 20 minutes and take readings. In the lab,
the incubation method is used. The sample is sealed in a Mason Jar and then incubated to let
things build up inside it.
, How do the different soil management practices employed at Kellogg Biological Station affect
greenhouse gas fluxes to/from soils and the total global warming potential (GWP)? - CORRECT
ANSWER -1) No till, alfalfa/poplar was fast growing and harvested for biofuel perennials
2) Early successional community had the highest impact
3) Organic underperformed because they need to be tilled for it to work
4) Methane uptake in all systems, but the most in late succession- (methanotrophs populations
specialize in absorbing CH4 and find success in stable late successional
communities
5) Alfalfa absorbs the most N2O, all till methods release the same N2O
If you look at net change: early successional had best result, poplar second best, alfalfa worse
since it is expensive to lime, and conventional tilling far worse, no till releases a small amount of
CO2, biggest change for the least effort
How can agricultural soils be used to mitigate climate change and the potential of different
agricultural practices to reduce atmospheric CO2 concentrations (Paustian et al 2016)? -
CORRECT ANSWER -Agricultural practices that increase C include:
1) improved varieties of species with greater root mass to deposit C in deeper layers where
turnover is slower
2) adopting crop rotations that provide greater C inputs
3) more residue retention
4) cover crops during fallow periods to provide year-round carbon inputs
5) zero-tillage practices
6) compost and biochar
Describe the key take-home messages about the impacts of soil warming, nitrogen fertilization,
and their interactions observed at the Harvard Forest Soil Warming x NitrogenAddition Study -
CORRECT ANSWER -Higher plant C inputs below ground, combined with treatment, drive higher
soil respiration rates, along with new SOM formation. Soil C loss in response to warming may be
less than previous estimates obtained from single factor studies. Coupling two important global
WITH CORRECT ANSWERS
How are soils impacted by climate change and how do they impact climate change? - CORRECT
ANSWER -Soil moisture and temperature influence greenhouse gas fluxes from the soil.
Approximately 20% of soil carbon is lost due to warming. Elevated precipitation generally
increases plant productivity and carbon inputs to soils; drought typically reduces plant growth
and carbon inputs. Drought limits soil respiration, whereas increased precipitation stimulates
respiration. Soil freezing and thawing increase soil carbon and nutrient availability due to
microbial and root cell lysis and/or soil aggregate disruption.
How is climate expected to change in the Northeastern U.S.? - CORRECT ANSWER -The
Northeastern U.S. is expected to have a temperature increase of 1.1 degrees C. By 2070, the
climate will resemble South Carolina or Florida. Spring time will arrive three weeks earlier and
summer will be three weeks longer. We'll receive more precipitation in the winter and more
drought in the summer. Less snow will fall and they'll be an increase in extreme weather events.
How do soil organisms release CO2 and other trace gases to the atmosphere (or in some cases,
take up greenhouse gases from the atmosphere)? - CORRECT ANSWER -Soil microbes uptake C
and then respire CO2. They are highly abundant in the soil, and their activity at the ecosystem
level affects a global scale. Soils also release greenhouse gases such as methane, found in
wetland environments (oxic soils), and nitrous oxide, produced through nitrification and
denitrification.
How is soil respiration measured in both the field and lab? - CORRECT ANSWER -In the field, the
static chamber method or auto chamber method are used to determine soil respiration. In the
static chamber method, a pbc collar is pushed into the soil about 3-5 cm. The collar is lidded
and a sample is taken up with a syringe and a gas chromatograph analyzes it. The auto-chamber
method is set up to open and close on their own every 20 minutes and take readings. In the lab,
the incubation method is used. The sample is sealed in a Mason Jar and then incubated to let
things build up inside it.
, How do the different soil management practices employed at Kellogg Biological Station affect
greenhouse gas fluxes to/from soils and the total global warming potential (GWP)? - CORRECT
ANSWER -1) No till, alfalfa/poplar was fast growing and harvested for biofuel perennials
2) Early successional community had the highest impact
3) Organic underperformed because they need to be tilled for it to work
4) Methane uptake in all systems, but the most in late succession- (methanotrophs populations
specialize in absorbing CH4 and find success in stable late successional
communities
5) Alfalfa absorbs the most N2O, all till methods release the same N2O
If you look at net change: early successional had best result, poplar second best, alfalfa worse
since it is expensive to lime, and conventional tilling far worse, no till releases a small amount of
CO2, biggest change for the least effort
How can agricultural soils be used to mitigate climate change and the potential of different
agricultural practices to reduce atmospheric CO2 concentrations (Paustian et al 2016)? -
CORRECT ANSWER -Agricultural practices that increase C include:
1) improved varieties of species with greater root mass to deposit C in deeper layers where
turnover is slower
2) adopting crop rotations that provide greater C inputs
3) more residue retention
4) cover crops during fallow periods to provide year-round carbon inputs
5) zero-tillage practices
6) compost and biochar
Describe the key take-home messages about the impacts of soil warming, nitrogen fertilization,
and their interactions observed at the Harvard Forest Soil Warming x NitrogenAddition Study -
CORRECT ANSWER -Higher plant C inputs below ground, combined with treatment, drive higher
soil respiration rates, along with new SOM formation. Soil C loss in response to warming may be
less than previous estimates obtained from single factor studies. Coupling two important global
