Clima Climate, W Water ter, and Ecosy and Ecosystems: tems: A Futur A Future of of Sur Surprises prises Robert Harriss Houston Advanced Research Center Changsheng Li Changsheng Li Steve Frolking University of New Hampshire
Climate change is not uniform geographically A Average T for 2001-2005 compared to 1951-80, degrees C T f 2001 2005 d t 1951 80 d C J. Hansen et al., PNAS 103 : 14288-293 ( 2006)
And T is not the only factor that’s changing NCDC, 2000 Effect is not uniform; most places getting wetter, some getting drier.
Mitigation and Adaptation to Climate Change By Design Change By Design • Carbon dioxide is primary greenhouse gas but • Carbon dioxide is primary greenhouse gas, but methane, nitrous oxide, CFC’s, ozone, and black soot also contribute to climate change. g • Significant climate change mitigation benefits Significant climate change mitigation benefits can be derived by reducing nitrous oxide and methane emissions from agriculture.
Climate forcing agents in the industrial era. “Effective” forcing accounts for C ate o c g age ts t e dust a e a ect e o c g accou ts o “efficacy” of the forcing mechanism Source: Hansen et al., JGR, 110 , D18104, 2005.
Inefficiencies in fertilizer nitrogen use offer important opportunities for mitigation of important opportunities for mitigation of nitrous oxide emissions N N Fertilizer N Fertilizer N N N Consumed Produced Applied in Crop In Feed in Store 100 31 94 7 47 4 -3 3 -6 6 -47 47 -16 16 -24 24 4% of the N produced in the Haber-Bosch process and used for animal production enters the human mouth. Galloway JN and Cowling EB. 20
DNDC: A Computer-aided Tool for P Precision Land Management i i L d M t DNDC Reveals the mechanisms that drive ecosystem change by tracking movement of chemical elements between life and its environment chemical elements between life and its environment DNDC allows users to construct scenarios that DNDC allows users to construct scenarios that benefit land managers and enhance environmental protection. DNDC can stimulate innovation and information sharing relevant to creating better landscape h i l t t ti b tt l d management for people and nature
http://www dndc sr unh edu http://www.dndc.sr.unh.edu
N inputs p N N 2 N 2 O, N 2 , NO x HNO 3 , etc gas losses Plant N NH 4 NH 4 + N distribution N distribution N NO 3 - Microbial N Microbial N Soil N N losses leaching
Stratospheric effects Atmosphere Particulate N2O Matter NO NO x effects Ozone Greenhouse effects effects N2O NHx NH3 NH3 NOy NOy NO NOx Energy production Terrestrial Ecosystems Forests & Grasslands G l d NH NHx effects Agroecosystem NOy Plant Food NHx effects production Animal Crop N2O (terrestrial) Soil Soil Norganic NO3 Coastal People effects (food; fiber) N2O Surface water Surface water (aquatic) effects Aquatic Ecosystems y et al., Ocean effects Groundwater effects 03 Galloway 200 Indicates denitrification potential
The DNDC Model ecological Climate Soil Vegetation Human activity drivers drivers water demand daily growth annual litter average water uptake water uptake potential temp. N-demand CO 2 very labile labile resistant evapotrans. microbes water stress LAI-regulated N-uptake grain albedo evap. trans. NH 4 + labile resistant vertical water stem soil temp humads flow flow root respiration root respiration s s profile roots DOC labile resistant Plant growth soil moist O 2 soil Eh O 2 use profile diffusion profile passive humus Soil climate Decomposition effect of temperature and moisture on decomposition soil Temperature Moisture pH Eh Substrates: NH 4 + , NO 3 - , environmental DOC factors NO 2 - NH 4 + CH 4 nitrate NO DOC nitrifiers CH 4 production DOC soil Eh denitrifier - NO 3 clay- NH 3 aerenchyma aerenchyma CH 4 oxidation CH 4 oxidation N 2 O N 2 O nitrite nitrite NH + + NH 4 denitrifier NO 3 - N 2 O NO DOC N 2 NH 3 N 2 O CH 4 transport denitrifier Denitrification Nitrification Fermentation
DNDC bridges between inputs and outputs INPUT INPUT INPUT PROCESSES OUTPUT Climate Cli t - Temperature Used by Emissions of - Precipitation soil N2O, NO, N2, - N deposition microbes CH4 and CO2 Soil properties DNDC - Texture - Organic matter Availability - Bulk density 1. Soil water movement of water, - pH pH 2. Plant-soil C dynamics 2 Plant soil C dynamics C Competition titi NH4, NO3, N leaching 3. N transformation and DOC Management - Crop rotation Crop rotation - Tillage Used by Growth of crop - Fertilization plants biomass - Manure use - Irrigation - Grazing - Grazing
DNDC DNDC Simulating carbon in soils and Simulating carbon in soils and ecosystems y
Model performance can be tested based on short- or long-term observations on C fluxes long term observations on C fluxes
DNDC Simulating nitrogen in soils and ecosystems ecosystems
N2 2O flux, g N/ha /day 1000 1500 2000 2500 3000 3000 3500 4000 4500 5000 500 0 106 123 140 157 N2O Fluxes from a Organic Soil at Glades, Florida, 1979-80 174 191 208 225 242 259 276 293 310 327 g 344 361 13 30 Field Day 47 64 Model 81 98 115 132 149 166 183 200 217 234 251 268 285 302 319 336 353
Observed and Modeled N 2 O and NO Emissions from a Spruce Stand at Hoglwald Forest in Germany in 1995 1997 Stand at Hoglwald Forest in Germany in 1995-1997 N 2 O NO
Observed and DNDC-Modeled N2O Fluxes from Agricultural Soils in the U.S., Canada, the U.K., Germany, New Zealand, China, Japan, and Costa Rica 1000 R 2 = 0.84 R 0.84 /ha/year 0.4 100 0.34 0. 0.41 O flux, kg N/ 0.43 0.4 0. 0.37 10 0. 0.032 0.035 0.037 0.011 0.032 Modeled N2O 0.050.032 0.032 0.031 0.015 0.035 0.029 0.033 0.035 0.028 0. 1 0.05 M 0.1 0 1 1 1 0 029 0.029 10 10 100 100 1000 1000 0.01 0.029 0.015 0.01 0.02 0.025 0.025 0.019 0.006 0.019 0.1 Observed N2O flux, kg N/ha/year
Sensitivity of N 2 O flux to environmental factors
Goal: Predicting impacts of management alternatives on C and N dynamics in terrestrial ecosystems on C and N dynamics in terrestrial ecosystems A change in management Vegetation Climate Other Soil management Yield N leaching C t C storage T Trace gas
A scenario of best management practices A scenario of best management practices was composed with (1) no-till, (1) increased depth of fertilizer application (1) increased depth of fertilizer application, (3) three splits of fertilizer application, and (4) non-legume cover crop (4) non legume cover crop.
Impacts of conventional tillage (CT), no-till (NT) and best management practices (BMP) for a crop field t ti (BMP) f fi ld at Story County, Iowa CT NT BMP Unit Fertilizer use F tili 120 120 120 120 120 120 k kg N/ha N/h Crop yield p y 4188 3830 4138 kg C/ha g dSOC -86 415 996 kg C/ha N leaching 47 20 8 kg N/ha N2O N2O 19 19 28 28 16 16 kg N/ha kg N/ha
Summary • Precision management of fertilizer use can provide significant reductions in nitrous oxide emissions while maintaining crop yields. Co-benefits can include i i i i ld C b fi i l d reductions in water pollution that results from leaching of nitrate. • Soil carbon and nitrogen must be treated as an integrated management issue to achieve maximum benefits. • The DNDC precision management tool can also be applied The DNDC precision management tool can also be applied to the management of timber, pastures, rice, and other landscapes. • A market based fertilizer reduction program could offer a • A market-based fertilizer reduction program could offer a fast-track approach to reductions in nitrous oxide emissions and nitrate pollution.
Summary Uncertainties, unclear signals, and long time scales are characteristic of climate, water, and ecosystem interactions We argue that there and ecosystem interactions. We argue that there is a strong rationale for enhanced policy flexibility and innovation using a portfolio of reactive, adaptive, and precautionary land e c ve, d p ve, d p ec u o y d management strategies.
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