Master of Forestry Science Carbon sequestered by native restoration plantings, southern Port Hills and Quail Island, Canterbury. Student: Paula D. Yarur Thys Student ID: 29574350 Supervisor: David Norton Co-Supervisor: Euan Mason April 30th 2021 School of Forestry, University of Canterbury Abstract Restoration plantings are typically planned with a multi-goal framework. Carbon sequestration has been a common component of these since the early nineties, but we know little about how plantings in different locations achieve this goal and what improvements can be made. This study investigated the above-ground biomass (AGB) held at five native restoration sites on the southern Port Hills and Quail Island. Date of planting was key to locate randomised sampling sites in satellite imagery using GIS. Temporary plots were set out in the field to measure all AGB and two allometric equations were applied to the measured data to estimate carbon expressed as CO2 equivalents. Data analysis was undertaken using R statistical software. A comparison was made between the primary allometric equation used in New Zealand’s national carbon accounting system (which is based mainly on mature trees) and an allometric equation based on shrubs. Results showed an average 9% increase in the total CO2 equivalent for all plots when using the mature tree equation for plantings less than 60 years old. A revision of the allometric equations used may improve the accuracy of the carbon accounting system if time and costs are not a limitation. Plot species-composition variables and environmental variables were not found to have a significant influence on CO2 equivalent in the restoration plantings. However, the CO2 equivalent amounts differed from those of the MPI native species look-up tables at 30 years post planting. The values suggest that a restoration planting with biodiversity objectives can reach higher carbon content the older they are and up to at least 59 years with no indication of an abatement in this. It was also found that Podocarpus totara can be used as an enhancement species to increase CO2 equivalent levels in restored areas. To enhance CO2 equivalent levels in tōtara plantings, proper management is necessary including elimination or at least reduction of ungulates and for trees to be planted on the forest’s edge. Attention to management, species composition, and use of enrichment species for current restorations would improve carbon content and hence to efficiently achieve our carbon goals. 1 Table of Contents ABSTRACT .................................................................................................................................... 1 CHAPTER ONE – INTRODUCTION, BACKGROUND AND STUDY AIMS ............................................... 6 INTRODUCTION ........................................................................................................................... 9 BACKGROUND ........................................................................................................................... 11 CARBON AND CLIMATE CHANGE ............................................................................................................... 11 COMMUNITY RESTORATION PLANTINGS AND CARBON SEQUESTRATION ........................................................... 13 NATIVE SPECIES, CARBON CONTENT AND BIODIVERSITY ................................................................................ 13 ENRICHMENT PLANTING .......................................................................................................................... 14 MEASURING CARBON CONTENT AND ALLOMETRIC EQUATIONS ...................................................................... 15 THESIS AIM ................................................................................................................................ 16 CHAPTER TWO – STUDY AREA AND METHODOLOGY ................................................................... 18 STUDY AREA .............................................................................................................................. 18 PORT HILLS ........................................................................................................................................... 18 QUAIL ISLAND ....................................................................................................................................... 19 STUDY SITES .............................................................................................................................. 20 TAI-TAPU ............................................................................................................................................. 20 QUAIL ISLAND ....................................................................................................................................... 20 KENNEDYS BUSH RESERVE ....................................................................................................................... 20 OHINETAHI RESERVE .............................................................................................................................. 20 HOON HAY RESERVE .............................................................................................................................. 20 METHODOLOGY ......................................................................................................................... 23 THE RANDOMISATION OF PLOTS ............................................................................................................... 23 PLOTS .................................................................................................................................................. 24 FIELD INSTRUMENTS ............................................................................................................................... 26 FIELD MEASUREMENTS AND ALLOMETRIC EQUATIONS .................................................................................. 26 LIVE ABG MEASUREMENTS FOR TREES, SHRUBS AND SAPLINGS...................................................................... 26 TREES, SHRUBS AND SAPLING RECORDINGS ................................................................................................ 27 QUADRATIC MEASUREMENTS .................................................................................................................. 27 SPECIES IDENTIFICATION ......................................................................................................................... 28 2 DATA AND ANALYSIS OF RESULTS .............................................................................................................. 28 ASSUMPTIONS ...................................................................................................................................... 29 SUMMARIES OF THE RESULT CHAPTERS ..................................................................................................... 29 Chapter 3. ...................................................................................................................................... 29 Chapter 4. ...................................................................................................................................... 29 Chapter 5. ...................................................................................................................................... 30 Chapter 6. ...................................................................................................................................... 30 CHAPTER THREE – RESULTS: ALLOMETRIC EQUATIONS ................................................................ 31 INTRODUCTION ......................................................................................................................... 31 METHODOLOGY ......................................................................................................................... 31 DATA PREPARATION AND ERROR CHECKING ................................................................................................ 31 BIOMASS CALCULATIONS ......................................................................................................................... 32 Tree equation: ............................................................................................................................... 32 Shrub equation: ............................................................................................................................. 32 Discrete plant equation: ................................................................................................................ 33 SLOPE AND PLOT CARBON ....................................................................................................................... 33 RESULTS .................................................................................................................................... 33 DISCUSSION ............................................................................................................................... 39 LIMITATIONS ............................................................................................................................. 41 CONCLUSION ............................................................................................................................. 41 CHAPTER FOUR – RESULTS: ENVIRONMENTAL CORRELATES ........................................................ 42 INTRODUCTION ........................................................................................................................