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Chris Goulding. Calculating the current and future carbon stocks from plot measurements in fast growing plantations. Outline of Presentation. Recap of NZ, the Kyoto Protocol and current situation Plot-based measurements - carbon pools Allometric equations Modelling Carbon Validation.
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Chris Goulding Calculating the current and future carbon stocks from plot measurements in fast growing plantations
Outline of Presentation • Recap of NZ, the Kyoto Protocol and current situation • Plot-based measurements - carbon pools • Allometric equations • Modelling Carbon • Validation
New Zealand27 million ha, 4 million people0.6 mil ha Kyoto forests within 1.8 mil ha
NZ Carbon Accounting System • To measure carbon stocks and stock changes • indigenous forests and shrublands • planted Kyoto and “pre-Kyoto” forests • Reporting under Article 3.3 of the Kyoto Protocol • net carbon stock changes • afforestation, reforestation and deforestation since 1990, • first period 2008 - 2012
What is a Forest? • Cycling between pasture and shrub/forest over the long term on land economically marginal for agriculture • minimum size of • 1 ha • 100 m width • 30 % tree species cover, • and • Potential to reach • 5 m height in situ
Planted Forests4 plot cluster,4x4 km gridremeasured every 3 yrs
Reporting Requirements Amount of C in the following pools : • Above-ground live biomass • Below ground live biomass (roots) • Dead wood (> 10 cm in diameter) • Litter (<10 cm in diameter) • Soil organic matter
DBH,H Temp Soil C:N Silvicultural History Allometric Equations Models Satellite Images Aerial Photos Carbon Density (t C/ha) Forest Area (ha) Carbon Stock (t C) C Accounting in Forests
Tree allometric equations • Functions developed for Radiata pine, Douglas fir, Eucalyptus spp, other spp. • Radiata pine, 737 tree sample, • W = 15.124 + 0.016 D2H • Where • W = above ground biomass (kg) • D = diameter breast height (cm) • H = total tree height (m) • Do not • explicitly account for live crown pruning • take into account regional trends in wood density • forecast the future
Carbon Prediction System –concept and model inputs • Plot measurement • Dbh, Height, stocking • Age and tending history • Site specific environmental data • Soil nitrogen fertility, air temperature • Silvicultural regime • Likely past/future pruning and thinning regime • 300Index, Wood density and C_Change models
Regime ( p a s t a n d f u t u r e s t o c k i n g / p r u n i n g ) Outerwood Density Top Height Age Stocking Basal Area 300 Index Density Model G r o w t h M o d e l Yield Table ( a n n u a l s t o c k i n g , s t e m v o l u m e & s t e m d e n s i t y ) C-Change Outputs: Annual Carbon Pools Plot data and model system Inputs: Processing:
Carbon yield table For each year, starting at planting, • 300 Index management growth model predicts stem volume increment • “Sheath” wood density model predicts Annual Wood density • C_change compartment allocation model partitions biomass / carbon to carbon pools, including decay. • Model system, by definition, passes through the plot measurement of ht, basal area, pruned height, stocking, thinned trees
Models: 300 Index • Estimates site volume productivity level from plot data and tending history • Applies future tending regime • Predicts stocking, stand height, and gross and net stem volume
Productivity Indices • 300 Index is a productivity index of volume growth. It is the Stem Volume Mean Annual Increment (MAI), at age 30, for a defined reference regime. • Site Index is a height growth productivity index. It is the Mean Top Height (MTH) at a reference age of 20 years. • Both productivity indices are required, and can be derived from plot measurement data.
300 Index versus Site Index - PSP historic data Volume and Height Productivity are only weakly related
Actual (solid lines) and predicted (dashed lines) BA for a fertile and infertile sites, 3 stockings at each site.
Models: Wood density • Either • measure breast height outerwood density at a known age • estimate breast height outerwood density from mean air temperature and C/N balance • Derive density of stem wood annual growth sheaths from age and stocking
Models: C_Change • Obtains gross stem wood/weight increments by age from volume and density models • Applies expansion factors to estimate total biomass & the carbon fixed • Partitions carbon fixed to live tree components • Calculates component mortality and transfers to dead pools using mortality functions and regime information • Applies decay rates to dead pools
Partitioning of biomass increment to above ground, live-tree components
Measured and predicted Above ground carbon 33 plots (95% CI).
Carbon Model validation95% confidence intervalmean prediction error (actual-predicted) 33 plots
Conclusions • Allometric equations and C_change model comparable figures for trees • Model system conditioned by the sample plot measurement • Volume yield model used operationally by managers • Model reduces estimation effort for smaller pools • It enables interpolation between measurements, forecasting and strategic planning.