Copyright is owned by the Author of the thesis.  Permission is given for 
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THE EFFECT OF AN INTEGRATED CATCHMENT 
MANAGEMENT PLAN ON THE GREENHOUSE GAS BALANCE 
OF THE MANGAOTAMA CATCHMENT OF THE 
WHATAWHATA HILL COUNTRY RESEARCH STATION 
 
 
A thesis presented in partial fulfillment of the requirements  
for the degree of 
 
 
 
Master of Science 
in 
Ecology 
 
 
 
 
At Massey University, Manawatu,  
New Zealand 
 
 
 
 
Daniel Smiley 
2012 
I 
 
ABSTRACT 
An integrated catchment management plan implemented in the Mangaotama 
catchment of the Whatawhata Research Station in 2001 demonstrated that Pinus 
radiata forestry on marginal land, along with conservation measures and 
intensification could produce a win-win outcome for economic output and the 
environment. However, greenhouse gas mitigation was never fully considered. 
This research investigated the effect of the plan on the land?s greenhouse gas 
balance and carbon stocks between 2000 and 2011. Historical records, modelling 
with OVERSEER and CenW, literature values and field measurements were used to 
account for CO2, CH4, and N2O from the four main land-use types: pasture, native 
forest, pine, and native plantings. The original land-use would have emitted a net 
10.99 Gg CO2e over 10yrs, whereas the new land-use sequestered a net 47.26 Gg 
CO2e in its first 10yrs. The total carbon stocks rose by 15.9 Gg C. Forestry 
conversion of almost half the area explained most of this effect. Agricultural 
intensification increased per hectare emissions from pasture, but overall pasture 
emissions were lowered by over half due to the reduction in livestock numbers. 
The native plantings had a small impact due to the small area planted and their 
slower growth compared with pines. Soil carbon was lost under all land-uses, 
except possibly in grazed native forests, but these conclusions were hampered by 
a scarcity of samples. Uncertainty also surrounded the modelling of the pine 
forest in complex terrain, which is not yet adequately captured in CenW. A 
preliminary look at carbon trading suggested that it could strongly undermine the 
viability of the original farm system, but it could also help to fund the expensive 
transition to the new land-use. Overall, it was found that in addition to the 
benefits already shown by the integrated catchment management plan, it was 
also an effective way of mitigating climate change. 
  
II 
 
ACKNOWLEDGEMENTS 
I thank my supervisors Dr Maria Minor and Dr Mike Dodd for their help in the 
development and completion of this project. I would like to thank Dr Maria Minor 
for her advice throughout  the project which has helped to bring it up to standard. 
Thanks is due to Dr Mike Dodd, who acted as my gateway to the Whatawhata 
farm, for the effort he has put in to recovering historical information for the site, 
relocating old sampling sites and helping with the soil sampling, all of which was 
invaluable in carrying out this project. Ian Power, Bill Carlson, and Bryan 
Stevenson also helped with relocating old sampling sites. Dr Alec Mackay 
provided much enthusiasm and enough ideas for several PhDs during the 
formulation of the project. Dr Miko Kirschbaum provided the CenW model and 
parameter files as well as advice on its use and comments, which helped refine 
the methods. Shane Hill provided and checked off the information on the 
management of the farm. I thank Lisa Bevan assisting with the math in my first 
attempts at modelling the climate. Thanks to Ian Furket for the soil sampling 
lesson and help with equipment. Special thanks are due to Robert Silberbauer and 
Tylee Reddy for helping with the fieldwork and doing so with good humor, 
optimism, and not a single broken bone despite the challenges of the pine forest. I 
thank Lynn Smiley for checking for errors in the final draft. I would like to thank 
AgResearch Ltd. for organizing and funding the analysis of the soil samples, the C. 
Alma Baker Trust for funding me during this research and the Bonded Merit 
Scholarship for contributing towards my fees. Lastly thanks are due to all those 
who have done research at Whatawhata in the past, without whom this study 
would have been impossible.  
  
III 
 
TABLE OF CONTENTS 
 
 
CHAPTER 1: INTRODUCTION .................................................................................................... 1 
1.1 INTRODUCTION ........................................................................................................................................ 1 
1.2 BACKGROUND ........................................................................................................................................... 2 
1.3 RESEARCH CONTEXT ............................................................................................................................... 5 
1.4 THESIS ORGANIZATION........................................................................................................................... 6 
CHAPTER 2: LITERATURE REVIEW ......................................................................................... 7 
2.1 INTRODUCTION ........................................................................................................................................ 7 
2.2 SUSTAINABLE AGRICULTURE & CLIMATE CHANGE ........................................................................... 7 
2.3 GREENHOUSE GAS CYCLING IN PASTORAL AGRICULTURE & FORESTS........................................ 10 
2.3.1  Greenhouse Gases .......................................................................................................... 10 
2.3.2  Carbon Stocks .................................................................................................................. 11 
2.3.3  Emissions........................................................................................................................... 13 
2.3.4  Other Fluxes ..................................................................................................................... 14 
2.3.5  Effect of Land Use Conversion on Soil Carbon ................................................... 16 
2.4 OPTIONS FOR ADDRESSING CLIMATE CHANGE ................................................................................ 17 
2.5 PREVIOUS STUDIES OF AGRICULTURAL GREENHOUSE GAS BALANCES ....................................... 19 
2.6 MARGINAL LANDS & CARBON SEQUESTRATION IN HILL COUNTRY ............................................ 21 
2.7 TREES IN HILL COUNTRY..................................................................................................................... 22 
2.8 ECOSYSTEM SERVICES & CARBON TRADING .................................................................................... 24 
2.9 PREVIOUS CARBON STUDIES AT WHATAWHATA ............................................................................ 25 
CHAPTER 3: METHODS .............................................................................................................. 29 
3.1 STUDY SITE ............................................................................................................................................ 29 
3.2 CONCEPTUALIZATION .......................................................................................................................... 33 
3.2.1  GHG Balance Methodologies ..................................................................................... 33 
3.2.2  System Boundaries ........................................................................................................ 35 
3.3 GLOBAL WARMING POTENTIALS ....................................................................................................... 37 
3.4 PASTURE................................................................................................................................................. 38 
3.4.1  Pasture Emissions .......................................................................................................... 38 
3.4.2  Sequestration .................................................................................................................. 44 
3.4.3  Carbon Stocks .................................................................................................................. 45 
3.5 NATIVE FOREST FRAGMENTS ............................................................................................................. 46 
3.5.1  Native Forest Emissions .............................................................................................. 46 
3.5.2  Sequestration & Carbon Stocks ................................................................................ 47 
3.6 NATIVE RESTORATION PLANTINGS ................................................................................................... 53 
3.6.1  Emissions........................................................................................................................... 53 
3.6.2  Sequestration & Carbon Stocks ............................................................................... 54 
3.7 PINE FOREST ......................................................................................................................................... 57 
3.7.1  Emissions........................................................................................................................... 57 
3.7.2  Sequestration & Carbon Stocks ................................................................................ 57 
3.8 EROSION ................................................................................................................................................. 65 
3.9 NET BALANCE CALCULATIONS ........................................................................................................... 66 
CHAPTER 4: RESULTS ................................................................................................................ 67 
4.1 THE ROLE OF EACH MAJOR LAND USE CHANGE .............................................................................. 67 
4.1.1  Conversion to Pine Forestry ....................................................................................... 67 
4.1.2  Pasture Reduction and Intensification .................................................................. 73 
4.1.3  Native Forest Fragments ............................................................................................ 76 
4.1.4  Native Restoration Plantings ................................................................................... 86 
IV 
 
4.2 COMPARISON OF FOREST TYPES WITH EACH OTHER, EMISSIONS TRADING SCHEME LOOK-UP 
TABLES, & PROJECTIONS FOR PINE GROWTH ......................................................................................... 88 
4.3 SOIL CARBON ......................................................................................................................................... 92 
4. 4 CATCHMENT NET GREENHOUSE GAS BALANCE & CARBON STOCKS .......................................... 94 
CHAPTER 5:  DISCUSSIO N ................................................................................................. 97 
5.1 SUMMARY: EFFECT OF THE CATCHMENT MANAGEMENT PLAN ................................................... 97 
5.2 INDIVIDUAL LAND USES, SENSITIVITY ANALYSIS & UNCERTAINTIES .......................................... 99 
5.2.1  Pine Forests ...................................................................................................................... 99 
5.2.2  Pasture ............................................................................................................................ 105 
5.2.3  Native Forest Fragments ......................................................................................... 108 
5.2.4  Native Restoration Plantings ................................................................................. 113 
5.2.5  Soil Carbon .................................................................................................................... 115 
5.2.6  Erosion ............................................................................................................................ 117 
5.2.7  Unaccounted for Components ................................................................................ 117 
5.2.8  Limits to Application Elsewhere ........................................................................... 118 
5.3 SCENARIOS ........................................................................................................................................... 119 
5.3.1  Scenarios Tested ......................................................................................................... 119 
5.3.2  Scenarios Results & Implications......................................................................... 120 
5.4 VALUATION .......................................................................................................................................... 123 
5.4.1  Valuation Methods ..................................................................................................... 123 
5.4.2  Valuation Results & Implications ......................................................................... 125 
5.5 CONCLUSIONS ...................................................................................................................................... 129 
REFERENCES ............................................................................................................................... 131 
APPENDIX A ................................................................................................................................ 138 
APPENDIX B ................................................................................................................................ 147 
 
 
 
 
 
  
V 
 
FIGURES 
Figure 1. Greenhouse gas cycling in a forest. The size of the arrows and boxes gives an 
approximate indication of the typical relative sizes of stocks and flows based on 
the values used throughout this study. Up arrows indicate emissions, down 
arrows sequestration. NPP = net primary productivity. ................................................. 12 
Figure 2. Greenhouse gas cycling in a grazed pasture. The sizes of the arrows and 
boxes give an approximate indication of the typical relative sizes of stocks and 
flows based on the values used in this study. Up arrows indicate emissions, down 
arrows sequestration. NPP = net primary productivity. ................................................. 12 
Figure 3. Methods for sequestering carbon (Lal, 2008). ............................................................ 17 
Figure 4. Location map of the study catchment (Dodd et al., 2008b). .................................. 29 
Figure 5. Distribution of land-use capability classes within the Mangaotama catchment 
(adapted from maps supplied by AgResearch Ltd.)........................................................... 30 
Figure 6. Land use in the Mangaotama catchment prior to 2001 (adapted from maps 
supplied by AgResearch Ltd.). ..................................................................................................... 31 
Figure 7. Land use in the Mangaotama after 2001 (adapted from maps supplied by 
AgResearch Ltd)................................................................................................................................. 32 
Figure 8. Slope and aspect classes that were used in modelling the pine forest. Shown 
for the whole catchment. When these two maps where overlaid they gave the 12 
slope/aspect classes. ....................................................................................................................... 58 
Figure 9. Relative solar radiation map for January. Darker shades are lower values 
(relatively less radiation). Minimum value = 0.017. Maximum value = 1.11. ........ 60 
Figure 10. Relative solar radiation map for July. Darker shades are lower values 
(relatively less radiation). Minimum value = 0.025. Maximum value = 1.79. ........ 60 
Figure 11. Carbon stocks and flows for pine forest in 2011 (example using values for 
steep Eastern slopes). Positive values are emissions, negative values are 
sequestration. Erosion refers to the fate of sediment exported from the 
catchment. ............................................................................................................................................ 69 
Figure 12. Growth rates of pine forest on different slope/aspect classes over a 30yr 
rotation (not including harvest). ?Other? is the mean for all non-southern slopes 
which showed considerable overlap in growth rates. Easy South was generally at 
the lower end of the range for ?Other? slopes. ..................................................................... 70 
Figure 13. Changes in the net greenhouse gas balance for the whole catchment and for 
the pine forest, from before the land-use changes in 2001 until 10yrs after. 
Positive values are net emissions and negative values are net sequestration of 
greenhouse gases. OLD ? old management regime (before conversion to pines 
and other land-use changes), TRA ? transitional period (pines planted and 
establishing), CUR ? current management regime (established pine forest). ....... 71 
Figure 14. Growth rates over a 30yr rotation (not including harvest) with thinning in 
2010 and without thinning included in the model, using the Steep East class as an 
example. ................................................................................................................................................ 72 
Figure 15. Stocks and flows for pasture in 2011 (using LUCC V steep slopes values). 
Livestock were not counted in the stocks. Positive values are emissions, negative 
values are sequestration. Erosion refers to the fate of sediment exported from 
the catchment. .................................................................................................................................... 73 
Figure 16. Changes in the net greenhouse gas balance for the whole catchment 
excluding the pine forests and for the pasture alone. Positive values are net 
emissions of gases. OLD ? old management regime (before conversion to pines 
and other land use changes), TRA ? transitional period (pines planted and 
establishing), CUR ? current management regime (established pine forest, 
increased N fertilizer). .................................................................................................................... 75 
Figure 17. Stocks and flows in grazed native forest in 2011 (example for LUCC VI). 
Livestock were not counted in the stocks. Positive values are emissions, negative 
values are sequestration. Erosion refers to the fate of sediment exported from 
the catchment. .................................................................................................................................... 79 
VI 
 
Figure 18. Stocks and flows for ungrazed native forest in 2011. Positive values are 
emissions, negative values are sequestration. Erosion refers to the fate of 
sediment exported from the catchment. ................................................................................. 80 
Figure 19. Changes in the net greenhouse gas balance for grazed and ungrazed forest 
fragments, and the native plantings for the whole catchment from before the 
land-use changes to 10yrs after. ?Ungrazed forest no soil? gives the values for the 
net sequestration in ungrazed forests when soil carbon losses are excluded. 
Positive values are net emissions and negative values are net sequestration. OLD 
? old management regime (before conversion to pines and other land use 
changes), TRA ? transitional period (pines planted and establishing), CUR ? 
current management regime (established pine forest increased N fertilizer). ..... 84 
Figure 20. Stocks and flows for native restoration plantings in 2011. Positive values 
are emissions, negative values are sequestration. Erosion refers to the fate of 
sediment exported from the catchment. ................................................................................. 87 
Figure 21. Carbon sequestration rate in forest biomass (live and dead plant matter) 
for different forest types in 2011, and the Emissions Trading Scheme (ETS) 
lookup table values for forests at age 10. ?Other pines? is the average of all non-
southern slope/aspect classes in the pine forest. ............................................................... 88 
Figure 22. Carbon in forest biomass (live and dead plant matter) for different forest 
types in 2011, and the Emissions Trading Scheme (ETS) lookup table values for 
forests at age 10. ?Other pines? is the average of all non-southern slope/aspect 
classes in the pine forest. ............................................................................................................... 89 
Figure 23. Pine forest biomass as projected at 30 years old, and the remaining biomass 
after harvest at 30 years. ?Other? is the mean of all non-southern slope/aspect 
classes. .................................................................................................................................................... 90 
Figure 24. Average sequestration rate in pine forests between year 10 and 30, as 
predicted by CenW. ?Other? is the mean of all non-southern slope/aspect classes.91 
Figure 25. Change in carbon stocks for the whole Mangaotama catchment and for the 
two major land uses before the land use changes (OLD) and for the following 
10yrs. Stocks include both soil and biomass pools. Pasture includes ungrazed 
riparian zones. OLD ? old management regime (before conversion to pines and 
other land use changes), TRA ? transitional period (pines planted and 
establishing), CUR ? current management regime (established pine forest). ....... 95 
Figure 26. Changes in the total carbon stocks for the native forest fragments and 
native plantings for the whole Mangaotama catchment from before the land use 
changes (OLD) until 10yrs after. Includes both plant biomass and soil pools. OLD 
? old management regime (before conversion to pines and other land use 
changes), TRA ? transitional period (pines planted and establishing), CUR ? 
current management regime with the established pine forest. ................................... 96 
Figure 27. Scenarios for changes in the net greenhouse gas balance for the whole 
catchment with planting the whole area in pines (pines only) or with planting 
only the steepest headwater sub-catchment in pines (Headwater Pines). ........... 121 
Figure 28. Scenarios for changes in the net greenhouse gas balance for the whole 
catchment if planting the whole area in natives (all native plantings) and if the 
whole area was degraded native forest (all native forest). .......................................... 121 
Figure 29. Scenarios for changes in the net greenhouse gas balance for the whole 
catchment with pasture intensification only, planting 15m riparian buffers on the 
main stream only (7.27ha) and planting 15m buffers on all streams (55.29 ha).122 
 
  
VII 
 
TABLES 
Table 1. Values used in deriving the stocking rates for input into OVERSEER. (SU = 
stock units, LUCC = Land use capability class, OLD = old land use, TRA/CUR = 
transitional and current land uses, Na = not available) ................................................... 39 
Table 2. Inputs for the OVERSEER model used in the calculation of enteric methane 
and nitrous oxide emissions in grazed pasture.(SU = stock units, LUCC = land use 
capability class, OLD = old land use, TRA/CUR = transitional and current land 
uses) ........................................................................................................................................................ 40 
Table 3. Amounts of inputs used on pasture during the different time periods, used in 
calculating embodied and combustion emissions. (OLD = old land use, TRA = 
transitional period, CUR= current land use). ........................................................................ 42 
Table 4. Emission factors for embodied emissions and fuel combustion for inputs used 
on pasture. Emission factor x amount of input = kg Co2e. ............................................... 42 
Table 5. Beef and lamb live-weights used in the calculation of emissions from decay of 
agricultural products (LW = Live-weight). ............................................................................ 43 
Table 6. Slopes and intercepts from linear regressions of 2011 heights and DBH used 
in the estimation of unmeasured tree heights in native forest. Those marked with 
a dash were not significant at a 0.1 level and the values given for "Trees" or "Tree 
Ferns" were used. Na = not applicable. ................................................................................... 48 
Table 7. Data used in the calculation of soil carbon stocks for the native fragments 
under the original land-use regime. From the study by Stevenson (2004). ........... 52 
Table 8. Amounts of inputs applied to native plantings during the planting and 
establishment phases used in calculating embodied and combustion emissions.54 
Table 9. Emission factors for embodied emissions, and fuel combustion for inputs 
used on native plantings. Emission factor x amount of input = kg CO2e. .................. 54 
Table 10. Relative solar radiation and slope values for the landscape divisions used in 
the adjustment of the climate input data to account for topography in the CenW 
model used in modelling the pine forest.(?Flat? was not used in the model but is 
shown for comparison). ................................................................................................................. 61 
Table 11. Pruning and thinning values used in calculating the inputs for the harvesting 
events in CenW. .................................................................................................................................. 62 
Table 12. Additional inputs into the CenW model. ....................................................................... 62 
Table 13. Field measurements of the Pinus radiata forest. Each class had a maximum 
of two sampling sites. The slope and aspect for both sites are shown, separated 
by a comma. Slopes and aspects are only approximate values for the area. .......... 64 
Table 14. Emissions and sequestration due to erosion under forests and pasture. ...... 65 
Table 15. Modelled yearly changes in pine biomass carbon (t C ha-1) from planting in 
2001 to 2011 for each slope/aspect class. ............................................................................. 67 
Table 16. Modelled (Predicted DBH) and measured (Field DBH) diameters at breast 
height for pine forests by slope/aspect class. Together with the differences 
between GIS-derived slopes (Model average slope), and slope and aspect 
measured in the field (Field site slopes, Field site aspects). Predicted DBHs 
marked with * are outside the 95% confidence intervals for the measured DBHs, 
shown in brackets. Field site aspects marked with * are outside the aspect class 
used in the model (i.e. these were borderline sites). Aspect classes in the model 
were: North = 315-45?, East/West= 45-135? & 225-315?, South =135-225?. Field 
site slopes and aspects are approximate for the general sampling area. Where 
two values are given for slope or aspect, they are for different sites. ....................... 68 
Table 17. Contribution of ruminant CH4, N2O and soil loss to total per ha emissions 
from each LUCC and each time period in pasture. Note: this is based on Steep 
slopes. Soil loss is not occurring on Easy slopes. OLD = the old regime pre-2001, 
TRA = the transitional period with higher stocking rates, CUR = the current 
regime higher fertilizer inputs. ................................................................................................... 74 
Table 18. P-values for mixed model ANOVAs for native forest fragments? total carbon 
mass in biomass (live mass, coarse woody debris, and litter) between the year 
VIII 
 
2000 to 2011, and the yearly change in carbon in live plants over the three 
sampling intervals used. SLOPE: Easy (n=6), Moderate (n=16), Steep (n=15). 
ASPECT: East (n=2), North (n=13), Northwest (n=7), South (n=15). 2011 values 
do not include plots from the ?Kohekohe? Forest. Values in bold are significant at 
?=0.1. ...................................................................................................................................................... 76 
Table 19. Total carbon mass (live biomass, coarse woody debris and litter) in t C ha-1 
for the native forest fragments by slope class. 95% confidence intervals are in 
brackets. Replication in 2011 is Easy =5, Moderate = 12, Steep = 9. Prior to 2011 
replication was Easy =6, Moderate =16, Steep = 15. ......................................................... 77 
Table 20. P-values for mixed model ANOVAs for litter mass in the native forest 
fragments. SLOPE: Easy (n=6), Moderate (n=16), Steep (n=15). ASPECT: East 
(n=2), North (n=13), Northwest (n=7), South (n=15). Values in bold are 
significant at ?=0.1. .......................................................................................................................... 78 
Table 21. Mean litter mass (t C ha-1) for the native forest fragments by slope. Easy 
(n=6), Moderate (n=16), Steep (n=15). ................................................................................... 78 
Table 22. Mean litter mass (t C ha-1) for the native forest fragments by aspect. East 
(n=2), North (n=13), Northwest (n=7), South (n=15). ..................................................... 78 
Table 23. Average live carbon mass in native forest fragment in 2000-2011, and yearly 
change in live carbon for the three sampling intervals used for all plots. 
Unsampled plots for 2011 (n=12) used 2008 values in calculating the mean. 95% 
confidence intervals in brackets. (Note: the comparison between 2011 and prior 
years is misleading due to differences in methods). ......................................................... 81 
Table 24. Average amounts of Coarse Woody Debris in the native forest fragments in 
2011. N = number of plots. 95% confidence intervals are in brackets. 
?Rewarewa? includes the fragment sometimes referred to as ?Kahikatea?............ 82 
Table 25. Mean litter mass in native forest fragments, 2000-2011. 95% confidence 
intervals are in brackets................................................................................................................. 82 
Table 26. Summary statistics for differences in the total change in carbon stocks in 
plant-associated carbon pools (live biomass, coarse woody debris and litter) 
between grazed and ungrazed native forest fragments. Negative values are losses 
of carbon (emissions) whereas positive values are a gain in carbon 
(sequestration). .................................................................................................................................. 82 
Table 27. Mean contribution of different size classes of trees and tree ferns to the total 
live carbon mass in native forest fragments, for all plots measured in 2011. ....... 83 
Table 28. Summary statistics for total plant associated (live, coarse woody debris, 
litter) carbon mass in native forest fragments between the year 2000 and 2011, 
and the yearly change for the three sampling intervals used. 95% confidence 
intervals of the mean are in brackets. (Note: the comparison between 2011 and 
prior years is misleading due to differences in method; 2011 uses 2008 data to 
fill missing values). ........................................................................................................................... 83 
Table 29. P-values for ANOVAs on live carbon in native plantings mass from February 
2002 to 2006 and the yearly carbon change in 2002 and from 2002 to 2006. 
SLOPE: Flat (n=3), Easy (n=14), Steep (n=16). ASPECT: Flat (n=3), East (n=11), 
West (n=9), North (n=5), South (n=5). SECTION: 10 different planting areas 
(n=1-5). Values in bold are significant at ?=0.05. ............................................................... 86 
Table 30. Summary statistics for native plantings ? live carbon mass and yearly 
change in carbon mass. 95% confidence interval for the mean is in brackets. ..... 86 
Table 31. Changes in soil carbon by land-use and soil depth between 2001 (pre-land-
use change) and 2011. N = sample size, ?Change? is the difference between the 
two means and the p-value is from paired t-tests for the difference between the 
two means. NA = Not applicable. The p-values in bold are significant at D=0.1. 
95% confidence intervals of the mean are in brackets. ?top? = 0-10cm depth. 
?sub?=10-20cm depth, each sample was calculated from a compound of 10 cores 
for carbon % and mean of two bulk density cores per depth. ...................................... 93 
Table 32. Changes in soil carbon by land-use and slope between 2001 (pre-land-use 
change) and 2011. N = sample size, ?Change? is the difference between the two 
IX 
 
means and the p-value is from paired t-tests for the difference between the two 
means. NA = Not applicable. The p-values in bold are significant at D=0.1. Total 
sampling depth is 20cm, each sample was calculated from a compound of 10 
cores for carbon % and the mean of two bulk density cores at two depths. Mod. = 
moderate. .............................................................................................................................................. 93 
Table 33. Total net balances of each land use during each time period; positive values 
are net emissions, negative values are net sequestration. OLD ? 1yr long, old 
management regime (before conversion to pines and other land-use changes). 
TRA ? 5yrs long, transitional period (pines and natives planted, fragments and 
riparian zones fenced). CUR ? 6yrs long, current management regime 
(established pine forest and increased fertilizer use). Na = not applicable. ?no 
soil? = soil carbon loss excluded. ................................................................................................ 94 
Table 34. Sensitivity analysis of silvicultural and other inputs, and climate adjustment 
parameters for the Steep East class in CenW. Values above 3% in bold. Negative 
values indicate lower biomass than in the original model. Changes to the date of 
thinning also involved shifting the last pruning to coincide with the new date, as 
per the original model. .................................................................................................................. 101 
Table 35.  Sensitivity analysis of climate parameters for Very Steep Southern class in 
CenW. .................................................................................................................................................... 102 
Table 36. Sensitivity analysis for OVERSEER. Based on Class V land for the old land-
use regime. Values above 3% in bold. Negative values indicate lower emissions 
than in the original model. .......................................................................................................... 107 
Table 37. Relative solar radiation values used in calculating the Climate Adjustment 
for the Average Slope method ................................................................................................... 125 
Table 38. Yearly cost of emissions under the baseline land-use in the Mangaotama 
catchment at three carbon prices. ETS uses the emissions trading scheme 
methods assuming all costs passed on to the farmer. Full balance uses all flows 
from the present study. ................................................................................................................ 126 
Table 39. The net cost of greenhouse gases from 2000 to 2011 (value of carbon credits 
minus the implementation costs of $597,840) at three carbon prices. Full balance 
uses all flows from the present study, ETS uses the emissions trading scheme 
methods assuming all costs passed on to the farmer. Surveyed Pines uses the 
Pine forest values from the present study, Look up table pines uses lookup table 
values for the pine forest. Positive values are a cost to the land-owner, negative 
values are a gain. ............................................................................................................................. 127 
Table 40. The effect of using the average slope and main aspect in calculating 
sequestration by the pine forest versus using all slope/aspect classes. % 
difference gives the Average slope method as a percent of the All classes method. 
Shows sequestration for the pine forest biomass for the actual area planted. ... 127 
  
X 
 
ABBREVIATIONS 
 
C Carbon 
CO2  Carbon Dioxide 
CO2e Carbon dioxide equivalents 
CH4 Methane  
CUR The current established land-use regime from 2006-2011 
CWD Coarse woody debris 
DBH Diameter at breast height 
DEM Digital Elevation Model 
DM  Dry matter 
DOC  Dissolved organic carbon 
ETS Emissions trading scheme 
FAO  Food and Agriculture Organisation 
GDP  Gross Domestic Product 
Gg Gigagram (1000 tonnes) 
GHG  Greenhouse gas 
GIS Geographic Information System 
GWP Global Warming Potential 
ha Hectare 
IPCC Intergovernmental Panel on Climate Change 
LUCC Land use capability class 
LW Live-weight (for lamb and beef carcasses) 
N2O Nitrous oxide 
NPP Net primary production 
NZU New Zealand unit 
OLD The old land-use regime, pre-2001 
ppb Parts per billion 
Pg Petagram (1,000,000 gigagrams) 
ppm Parts per million 
sph Stems per hectare 
SU Stock unit 
t Tonne 
TRA The transitional period to the new land-use regime from 2001-2006 
  
 
 
 
 
 
 
 
 
Chapter 1: Introduction 
 
1 
 
CHAPTER 1: INTRODUCTION 
1.1 INTRODUCTION 
Climate change is one of the world?s foremost environmental concerns. All 
nations and all sectors of society will be faced with its impacts and are obligated 
to address it. There is great concern that the costs of change are insurmountably 
high, given that emissions are bound to economic growth, and that the costs of 
inaction could be even greater (Stern, 2007). Therefore, there is an urgent need to 
find ways to reconcile our economic activities with this grave environmental 
threat. 
For New Zealand to do this, the problem is in creating viable yet ?carbon friendly? 
agricultural systems.  The agricultural sector is New Zealand?s biggest emitter of 
greenhouse gases, contributing 46.5% of total emissions in 2009 (Ministry for the 
Environment, 2011). It is also a major part of the national economy, contributing 
12.2% of GDP in 2010 (Ministry of Agriculture and Forestry, 2011e). The global 
demand for livestock products is only expected to increase due to the growing 
world population and its changing consumption patterns (Thornton, 2010), driving 
further development in this sector.  
Reforestation of marginal land, especially in hill country, is one option for 
mitigating emissions. An integrated catchment management plan for the 
Whatawhata Hill Country Research station combined reforestation and 
intensification, demonstrating that a win-win between growing trees and better 
farm profitability can be achieved (Dodd et al., 2008a). This approach could 
provide a workable system for hill country, likely to fit the criteria of being both 
productive and carbon neutral. However, its effects on greenhouse gas (GHG) 
mitigation have never been fully quantified. There is critical need to develop these 
types of farm systems, so further study is needed for the insights to be drawn out, 
improved and applied.  
The rest of this section briefly explores the basic background of these issues, and 
then outlines a study to investigate the greenhouse gas balance at of the 
Mangaotama catchment at Whatawhata.