The effect of residential property redevelopment on urban forest dynamics …

Research papers, University of Canterbury Library

As a global phenomenon, many cities are undergoing urban renewal to accommodate rapid growth in urban population. However, urban renewal can struggle to balance social, economic, and environmental outcomes, whereby economic outcomes are often primarily considered by developers. This has important implications for urban forests, which have previously been shown to be negatively affected by development activities. Urban forests serve the purpose of providing ecosystem services and thus are beneficial to human wellbeing. Better understanding the effect of urban renewal on city trees may help improve urban forest outcomes via effective management and policy strategies, thereby maximising ecosystem service provision and human wellbeing. Though the relationship between certain aspects of development and urban forests has received consideration in previous literature, little research has focused on how the complete property redevelopment cycle affects urban forest dynamics over time. This research provides an opportunity to gain a comprehensive understanding of the effect of residential property redevelopment on urban forest dynamics, at a range of spatial scales, in Christchurch, New Zealand following a series of major earthquakes which occurred in 2010 – 2011. One consequence of the earthquakes is the redevelopment of thousands of properties over a relatively short time-frame. The research quantifies changes in canopy cover city-wide, as well as, tree removal, retention, and planting on individual residential properties. Moreover, the research identifies the underlying reasons for these dynamics, by exploring the roles of socio-economic and demographic factors, the spatial relationships between trees and other infrastructure, and finally, the attitudes of residential property owners. To quantify the effect of property redevelopment on canopy cover change in Christchurch, this research delineated tree canopy cover city-wide in 2011 and again in 2015. An object-based image analysis (OBIA) technique was applied to aerial imagery and LiDAR data acquired at both time steps, in order to estimate city-wide canopy cover for 2011 and 2015. Changes in tree canopy cover between 2011 and 2015 were then spatially quantified. Tree canopy cover change was also calculated for all meshblocks (a relatively fine-scale geographic boundary) in Christchurch. The results show a relatively small magnitude of tree canopy cover loss, city-wide, from 10.8% to 10.3% between 2011 and 2015, but a statistically significant change in mean tree canopy cover across all the meshblocks. Tree canopy cover losses were more likely to occur in meshblocks containing properties that underwent a complete redevelopment cycle, but the loss was insensitive to the density of redevelopment within meshblocks. To explore property-scale individual tree dynamics, a mixed-methods approach was used, combining questionnaire data and remote sensing analysis. A mail-based questionnaire was delivered to residential properties to collect resident and household data; 450 residential properties (321 redeveloped, 129 non- redeveloped) returned valid questionnaires and were identified as analysis subjects. Subsequently, 2,422 tree removals and 4,544 tree retentions were identified within the 450 properties; this was done by manually delineating individual tree crowns, based on aerial imagery and LiDAR data, and visually comparing the presence or absence of these trees between 2011 and 2015. The tree removal rate on redeveloped properties (44.0%) was over three times greater than on non-redeveloped properties (13.5%) and the average canopy cover loss on redeveloped properties (52.2%) was significantly greater than on non-redeveloped properties (18.8%). A classification tree (CT) analysis was used to model individual tree dynamics (i.e. tree removal, tree retention) and candidate explanatory variables (i.e. resident and household, economic, land cover, and spatial variables). The results indicate that the model including land cover, spatial, and economic variables had the best predicting ability for individual tree dynamics (accuracy = 73.4%). Relatively small trees were more likely to be removed, while trees with large crowns were more likely to be retained. Trees were most likely to be removed from redeveloped properties with capital values lower than NZ$1,060,000 if they were within 1.4 m of the boundary of a redeveloped building. Conversely, trees were most likely to be retained if they were on a property that was not redeveloped. The analysis suggested that the resident and household factors included as potential explanatory variables did not influence tree removal or retention. To conduct a further exploration of the relationship between resident attitudes and actions towards trees on redeveloped versus non-redeveloped properties, this research also asked the landowners from the 450 properties that returned mail questionnaires to indicate their attitudes towards tree management (i.e. tree removal, tree retention, and tree planting) on their properties. The results show that residents from redeveloped properties were more likely to remove and/or plant trees, while residents from non- redeveloped properties were more likely to retain existing trees. A principal component analysis (PCA) was used to explore resident attitudes towards tree management. The results of the PCA show that residents identified ecosystem disservices (e.g. leaf litter, root damage to infrastructure) as common reasons for tree removal; however, they also noted ecosystem services as important reasons for both tree planting and tree retention on their properties. Moreover, the reasons for tree removal and tree planting varied based on whether residents’ property had been redeveloped. Most tree removal occurred on redeveloped properties because trees were in conflict with redevelopment, but occurred on non- redeveloped properties because of perceived poor tree health. Residents from redeveloped properties were more likely to plant trees due to being aesthetically pleasing or to replace trees removed during redevelopment. Overall, this research adds to, and complements, the existing literature on the effects of residential property redevelopment on urban forest dynamics. The findings of this research provide empirical support for developing specific legislation or policies about urban forest management during residential property redevelopment. The results also imply that urban foresters should enhance public education on the ecosystem services provided by urban forests and thus minimise the potential for tree removal when undertaking property redevelopment.

Question Time for 9 December 2010

Audio, Radio New Zealand

Questions to Ministers 1. CRAIG FOSS to the Minister of Finance: What reports has he received on the economy moving away from government spending, housing speculation and borrowing, and towards savings and exporting? 2. Hon PETE HODGSON to the Prime Minister: Does he stand by his answer to question No 11 yesterday that Sammy Wong did not accompany Pansy Wong on any ministerial trips to China? 3. HONE HARAWIRA to the Associate Minister of Health: What is the rationale behind the move to prohibit the display of tobacco products for sale in retail outlets? 4. Hon DARREN HUGHES to the Minister of Transport: Has he received any feedback or information in support of lowering the adult blood alcohol concentration to 0.05 that has given him any doubt or cause for reflection this year about his decision to retain the level at 0.08? 5. TIM MACINDOE to the Minister of Housing: What recent announcement has he made about the direction of social housing in New Zealand? 6. BRENDON BURNS to the Minister for Canterbury Earthquake Recovery: Is the Government's response package, announced last week to assist Canterbury businesses affected by the 4 September earthquake, universally supported by the Government and its supporters? 7. CATHERINE DELAHUNTY to the Minister for Social Development and Employment: Does she agree with the Alternative Welfare Working Group that welfare reform should be focused on "the relentless pursuit of well-being"? 8. Hon NANAIA MAHUTA to the Minister of Energy and Resources: Will the mining of lignite form part of his New Zealand Energy Strategy? 9. LOUISE UPSTON to the Minister of Education: What were the results of the Programme for International Assessment (PISA), which looked at New Zealand students' achievement in reading, maths and scientific literacy? 10. DARIEN FENTON to the Minister of Transport: How many emails has he received on the decision of the New Zealand Transport Agency to start charging CarJam and similar web-based information services for accessing the Agency's stored basic motor vehicle information? 11. JACQUI DEAN to the Minister of Agriculture: What recent steps has the Government taken to control bovine TB? 12. Hon TREVOR MALLARD to the Minister of Education: Which Minister is to be responsible for the enforcement of the Education Act 1989 in relation to limited attendance early childhood centres following the passing of the Education Amendment Bill (No 2)? Questions to Members 1. Hon DAVID CUNLIFFE to the Chairperson of the Finance and Expenditure Committee: How many submissions have been received on the Student Loan Scheme Bill? 2. Hon DAVID CUNLIFFE to the Chairperson of the Finance and Expenditure Committee: How many submitters on the Student Loan Scheme Bill have requested to be heard in person? 3. CHRIS HIPKINS to the Chairperson of the Local Government and Environment Committee: How many submissions have been received on the Sustainable Biofuel Bill? 4. CHRIS HIPKINS to the Chairperson of the Local Government and Environment Committee: How many submitters on the Sustainable Biofuel Bill have requested to be heard in person? 5. CHRIS HIPKINS to the Chairperson of the Local Government and Environment Committee: How many submissions have been received on the Southland District Council (Stewart Island/Rakiura Visitor Levy) Empowering Bill? 6. CHRIS HIPKINS to the Chairperson of the Local Government and Environment Committee: How many submitters on the Southland District Council (Stewart Island/Rakiura Visitor Levy) Empowering Bill have requested to be heard in person? 7. CHRIS HIPKINS to the Chairperson of the Government Administration Committee: How many submissions have been received on the Identity Information Confirmation Bill? 8. CHRIS HIPKINS to the Chairperson of the Government Administration Committee: How many submitters on the Identity Information Confirmation Bill have requested to be heard in person? 9. Hon PAREKURA HOROMIA to the Chairperson of the Māori Affairs Committee: How many submissions have been received on the Marine and Coastal Area (Takutai Moana) Bill? 10. Hon PAREKURA HOROMIA to the Chairperson of the Māori Affairs Committee: How many submitters on the Marine and Coastal Area (Takutai Moana) Bill have requested to be heard in person? 11. Hon DAVID CUNLIFFE to the Chairperson of the Finance and Expenditure Committee: Has the Finance and Expenditure Committee conducted the 2009/10 financial review of the Office of the Retirement Commissioner? 12. DARIEN FENTON to the Chairperson of the Transport and Industrial Relations Committee: How many submissions have been received on the Land Transport (Driver Licensing) Amendment Bill? 13. DARIEN FENTON to the Chairperson of the Transport and Industrial Relations Committee: How many submitters on the Land Transport (Driver Licensing) Amendment Bill have requested to be heard in person? 14. DARIEN FENTON to the Chairperson of the Transport and Industrial Relations Committee: How many submissions have been received on the Land Transport (Road Safety and Other Matters) Amendment Bill? 15. Hon DAVID PARKER to the Chairperson of the Justice and Electoral Committee: How many submissions have been received on the Lawyers and Conveyancers Amendment Bill? 16. Hon DAVID PARKER to the Chairperson of the Justice and Electoral Committee: How many submitters on the Lawyers and Conveyancers Amendment Bill have requested to be heard in person? 17. Hon DAVID PARKER to the Chairperson of the Justice and Electoral Committee: How many submissions have been received on the Legal Services Bill? 18. Hon DAVID PARKER to the Chairperson of the Justice and Electoral Committee: How many submitters on the Legal Services Bill have requested to be heard in person? 19. Hon DAVID PARKER to the Chairperson of the Justice and Electoral Committee: How many submissions have been received on the Sale and Supply of Liquor and Liquor Enforcement Bill? 20. Hon DAVID PARKER to the Chairperson of the Justice and Electoral Committee: How many submitters on the Sale and Supply of Liquor and Liquor Enforcement Bill have requested to be heard in person? 21. Hon DAMIEN O'CONNOR to the Chairperson of the Primary Production Committee: How many submissions have been received on the Food Bill? 22. Hon DAMIEN O'CONNOR to the Chairperson of the Primary Production Committee: How many submitters on the Food Bill have requested to be heard in person? 23. Hon DAMIEN O'CONNOR to the Chairperson of the Primary Production Committee: How many submissions have been received on the Dairy Industry Restructuring (New Sunset Provisions) Amendment Bill? 24. Hon DAMIEN O'CONNOR to the Chairperson of the Primary Production Committee: How many submitters on the Dairy Industry Restructuring (New Sunset Provisions) Amendment Bill have requested to be heard in person?