URBAN STREET TREE POLICY

Transcription

1 URBAN STREET TREE POLICY Endorsed by Council 21 July 2009

2 Table of Contents 1. INTRODUCTION WHY HAVE STREET TREES Environmental Social Economic CONSTRAINTS OF STREET TREES MAINTENANCE AND REPLACEMENT FUTURE FOR MANSFIELD S TREES Trees of significance Managing problem trees Future Plantings COMMUNICATING WITH OUR FRIENDS RECOMMENDATIONS Management of significant trees Removal of inappropriate trees and replacement plantings...8 APPENDIX INTRODUCTION TREE EVALUATION FEATURES OF EVALUATION Evaluation Objectives Elements for Evaluation Substitute Assessment Trees Less Than Five Years Old Replicate Assessment CALCULATION Introduction...12 APPENDIX PROPOSED STREET TREE PLANTING 2009 / PROPOSED PLANTING POSITIONS...14 PROPOSED TREE SPECIES...16 Page 2 of 17

3 1. INTRODUCTION The purpose of this policy is to provide a simple yet effective management approach for the long and short term future of street trees within the Mansfield Shire. A structured plan for urban street trees is necessary in identifying our obligations to public safety, the environment, native fauna and the general amenity of Mansfield Shire s urban areas. Mansfield Shire is fortunate to have a diverse range of trees, including 100 year old Elms overlooking the central business district, as well as the relatively new plantings of the Botanic Park and beautiful natives throughout the whole Shire. This document will provide Council with clear objectives and updated practices when managing trees within the Shire s urban areas. Maintaining the trees we have, and carefully planning our future plantings, will have a tremendous and positive influence on the future of our community. This document includes a proposed short term planting program for the township of Mansfield. It is recommended that surrounding town plantings and landscape projects are designed separately to this document while maintaining its theme and philosophy. 2. WHY HAVE STREET TREES We should not under estimate the role our street trees play in our life. Although many of the benefits are unseen, they support our community in many different ways. Street trees provide environmental, social and economic value to the community. 2.1 Environmental Air Quality Although we enjoy the clean clear air of the country, street trees can still improve our air quality. Trees provide oxygen, which is essential to clean air. Tree canopies also catch air borne dust and pollutants sheltering the community from these effects. Shade, Shelter and Light Street trees provide fantastic seasonal shade to pedestrians and vehicles. They also provide wind breaks and shelter from light rain. Deciduous trees also provide filtered light during winter enabling people and dwellings to benefit from winter sun. Microclimate Heat reflection from built surfaces such as buildings and footpaths create a warmer localised microclimate. Well designed street tree plantings can reduce the reflective heat from these surfaces and minimise our contribution to this issue. Water quality Street trees can filter and improve storm water runoff, providing our creeks and wetlands with a better standard of water. They also absorb storm water run off reducing risk of urban flooding. Wildlife Street trees, in particular native and indigenous varieties, provide food and shelter for wildlife. This should be a consideration when planting in urban areas, however greater consideration should be given when planting in open spaces and close to known wildlife corridors. Page 3 of 17

4 2.2 Social Aesthetics Street trees can influence an urban streetscape in many ways. The shape, colour, texture and variety all add to provide a unique quality to an area. Street trees can define a town s character. 2.3 Economic Street trees are known to increase property values considerably, especially in residential areas. As trees become more valued by the community, the economic influence of trees increases with it. This also applies to commercial areas who gain more business from customers who feel comfortable in their surroundings and are willing to spend more time in the business district. 3. CONSTRAINTS OF STREET TREES Safety It is natural part of a tree s life cycle to drop limbs throughout its life time. This can be a major hazard and has the potential to inflict harm to the community and damage infrastructure. Street trees can also produce trip hazards from roots lifting pavement and can become traffic hazards to vehicles. These issues can be limited with proactive auditing and maintenance programs and fast efficient reactive work to hazards as they are identified. Infrastructure Damage Trees can cause major problems for both Council property and private infrastructure. Kerb and channel work, footpaths, fences and buildings can all be affected by tree damage. It is important Council is aware of these potential issues and plans to reduce potential impact in future projects. Leaf Litter During autumn months leaf litter is a major issue for Mansfield Shire. It is very time consuming for Council to sweep drains and gutters of leaf litter. Leaf litter can block water flow and cause flooding in our streets. It also pollutes local waterways. Leaf litter can also be a pedestrian hazard and can look unsightly to the community. Weed Infestation Non native species of trees can cause weed infestation throughout the Shire. Seed carried in waterways, by wind or transported by humans, can propagate in other areas causing environmental issues. This can be counteracted by choosing non invasive species when practical and managing outbreaks when detected. Care should also be taken to ensure exotic species are not previously recognised troublesome plants. Page 4 of 17

5 Vandalism or unauthorised removal of street trees Council will not accept unauthorised removal or vandalism of street trees under any circumstances. As trees are becoming increasingly valued by the community, more efforts should be made to deter illegal removal of Shire trees. It is difficult to place a fiscal value to trees; however methods have been adopted by councils including City of Yarra and City of Melbourne in order to put a consistent value to trees. It would be advisable for Mansfield Shire to adopt one of these methods in order to evaluate its own trees (Appendix 1). Mansfield Shire has provisions within its Community Local Laws No. 1 to protect and prosecute if Council s street trees are vandalised or removed without permission. The Local Law states without a permit a person must not cut down, remove, or damage live or standing dead trees on a road. This should be expanded to all Council trees. Council has designed appropriate signage to be installed in areas where tree vandalism has occurred. See below for example of such signs. Mansfield Shire Council sign which can be erected in locations where tree vandalism has occurred. This practice has been widely adopted by metropolitan councils with the objective of deterring further unlawful acts on street trees. 4. MAINTENANCE AND REPLACEMENT Most street trees will need some maintenance throughout their life. Pruning, watering, fertilising and pest control are all part of our maintenance program. This can be minimised by choosing species of trees that are water efficient and not known for pest infestation. An example of this the Elm trees that although very mature have needed extra watering during the drought and costly annual pest control program. Page 5 of 17

6 5. FUTURE FOR MANSFIELD S TREES Mansfield 1909 Mansfield Trees of significance Mansfield Shire has many trees of significance, including avenues of honour, 100 year old Elm trees and 300 year old Eucalyptus trees. Trees can be classed as significant for many different reasons including their historical, social, environmental or cultural attributes. It is important that we protect these trees of significance, which may include developing local legislation to ensure their future. Despite efforts to protect these trees, it is realistic that some trees will not survive. Replacement plans need to be made now for the future of some of our trees including our 100 year old Elms in the central business district, as they will no doubt succumb to difficult climatic times or pest/disease invasion. 5.2 Managing problem trees The Elm trees in Mansfield s urban areas will need special consideration and care for the future. They, more than most other tree species, stand out as problem trees as they have particular management issues including: Elm Leaf Beetle infestation Intolerance to dry conditions Possibility of Dutch Elm Disease introduction to Australia. At present Council spends around $10,000 a year maintaining these issues. This routine program will need to be monitored as it may be economically unviable to continue due to climate change and the further threat of pest and disease. Future plantings of this species should be suspended. 5.3 Future Plantings It is very important that Mansfield Shire continues and increases its commitment to tree planting, both in urban and rural areas. Although native and indigenous species have many advantages, it is not always the best option to plant native trees. Continuation of themes should be considered when planning future landscapes. An open mind to non indigenous species may suit Mansfield s amenity in some cases. Page 6 of 17

7 Native plantings, low water tolerant and drought resistant species should always be the preferred option for future street tree projects. Planting to avoid future problems is also essential. Currently Mansfield has many examples of street trees and infrastructure in conflict with each other, such as plantings in Malcolm Street interfering with power lines and houses. This issue needs to be avoided otherwise Council will incur large management costs in the future. 6. COMMUNICATING WITH OUR FRIENDS It is important to note that Council is not the sole authority concerned by street trees. Other organisations such as VicRoads, power companies, telephone suppliers and community groups may need to be consulted before maintenance work be carried out on existing trees or future plantings are implemented. This should alleviate potential issues in the future. 7. RECOMMENDATIONS It is important to plan for the future yet not project too far as street trees could be influenced more short term such as seasonally. This document is designed to guide Mansfield Shire Council to manage the assets we have while further enhancing our street trees up to and including Management of significant trees Central business district Elm trees need remedial care such as dead wooding. A continued Elm Leaf Beetle program should be maintained and watering in dry conditions should also continue to ensure a long term future for these trees. Malcolm Street street trees interfering with power lines between Highett Street and The Parade should be removed and replaced with a more suitable street tree agreed upon with public consultation. See below photo of current issue with these trees. Remedial care of the Avenue of Honour along the Maroondah Highway should occur. Such things as pruning and dead wooding should be undertaken as a matter of priority, or an alternative tree planted in its place. As this is an avenue of honour, consultation with RSL and CWA should be undertaken. Avenue of Honour Malcolm St. Mansfield Page 7 of 17

8 7.2 Removal of inappropriate trees and replacement plantings A number of Plum trees in High and Highett Streets to be removed and replaced with an alternative species. See below photo for example. A suitable alternative should be found in consultation with Council staff and the community. These trees should be replaced in 2009/2010. Plum Tree, Highett Street Although Council has no current plans to remove the Elm trees in the central business district, a proactive replacement program should start in With a coordinated approach to replacement, new trees will have time to mature before the removal of the Elms take place in the future. Page 8 of 17

9 1. INTRODUCTION JEFF ALBRECHT GARDENS & GROUNDS FACILITIES & SERVICES DIVISION AUSTRALIAN NATIONAL UNIVERSITY APPENDIX 1 Trees are complex living organisms, each tree is individual, and therefore every tree has individual requirements. Trees are generally very tough and most trees can easily outlive a human life. Trees have the ability to adapt to different conditions and are often surviving in less than ideal situations. All parts of a tree including the roots, trunk, branches and leaves live in balance and are interdependent. A negative impact on any one of these parts will therefore impact on the whole of the tree. Trees cannot move and there is a limit to how much stress a tree can handle before it is either permanently damaged or dies. Be it logging or land development, tree issues never fail to provoke strong reactions in our communities both positive and negative. Tree protection is necessary as it is impossible to develop any environment without impacting on pre-existing trees. Successful tree preservation occurs when the goals of a development project are achieved with minimal impact to the trees designated for preservation. Success is measured over the long term when trees continue to thrive for many years after development has been completed. (Matheny & Clark 1998 Trees and Development P.1) 2. TREE EVALUATION These advantages include: Microclimate: a large tree can create a microclimate beneath its canopy, not only providing shade but also resisting against extremes in temperature. Habitat: trees provide a home for a multitude of bird, insect and animal life. Aesthetics: trees look good and if chosen correctly enhance the built environment. Soil stabilisation: tree roots bind the soil together preventing erosion. Psychological: trees make people feel good; in fact studies have proven that a green environment can reduce antisocial behavior. Despite the above-mentioned advantages people fail to treat trees as assets that have a monetary value just like a building or a motorcar and it is for this reason that arguments to protect trees are lost. The real-estate industry has long since been aware that a well planned landscape with mature trees can add up to 25% extra value to a site. Despite this fact valuable trees are constantly being removed or disrespected due to development projects. There are several excepted tree evaluation methods that can be used to attach a monetary value to a tree. The purpose of assigning a monetary value to an individual tree is to provide a means of objective, repeatable and consistent valuation. One such evaluation method commonly used is the Australian draft Standard (See section 2 below). In order to determine an accurate result a competent professional should carry out this method. Page 9 of 17

10 Tree values vary greatly depending on many factors with a value of between thousand dollars for a healthy mature tree. Trees that are particularly well developed, are an uncommon species, or have a particular historical significance can have a value in excess of $100,000. (The following pages give an explanation of how to use the Australian Draft Standard 1992 tree evaluation method and have been extracted from Mark Garner s Thesis - Determining an appropriate Protocol for Amenity Tree Valuation in Australia. 1999) 3. FEATURES OF EVALUATION 3.1 Evaluation Objectives The purpose of assigning a monetary value to amenity trees is to provide a means of objective, repeatable and consistent valuation, upon which the community can rely. This then will facilitate determinations on conservation, replacement or loss and other judgements affecting construction projects and the quality of life. 3.2 Elements for Evaluation Valuation elements shall be classified in accordance with this Section and Table Visual Impact The impact that the loss of a tree or group of trees within a specific location would have upon the landscape. If the tree is in a parcel of remnant vegetation in an urban area, the amenity value is greater, and would be assigned a higher value. Trees growing in a reserve or park should also be assigned a higher value. The value of poor shall refer to a tree where, if it were removed, there would not be a significant impact Frequency of occurrence Where a rare tree (a planted specimen) is under consideration, the upper value of 15 is appropriate. For a tree of common place the appropriate value for the tree is Historical significance Even though a tree may only have historical importance to a particular individual (eg. a tree planted to mark the death, or birth, of a relative) some value should be assigned to it. As the significance of the historical association increases, eg. national or localised importance, so must the value assigned Form and vigour A tree which is so badly damaged that its removal would improve the landscape, is assigned a low value. This is frequently the case with old, neglected street trees. The highest value is assigned to a tree in perfect form and excellent vigour. Page 10 of 17

11 3.2.5 Live crown size A tree with no live crown is assigned a value of 1.5 and the value of 15 is reserved for the exceptionally large tree. The width of the canopy multiplied by its height gives the live crown size, expressed in square metres. Depending upon species, the canopy may not be as important as the height or small, medium and large are appropriate. Other columnar species such as Lombardy poplar (Populus nigra italica) or pencil pine (Cupressus sempervirens var. stricta) should be considered as for palms Life expectancy Ten values are recognised, ranging from less than five years for a dying tree to 15 for a tree with a life expectancy of more than 100 years. NOTE: Life expectancy is the determination, at the time of valuation, to a tree s anticipated natural demise. Although a tree may be dead it may hold considerable historical importance and its value to the community may be immeasurable, however, this method is not able to accommodate dead trees. In such a case it may be appropriate for a historian to assess the tree for its value as a monument or relic Site suitability Values are assigned ranging from unsuitable for site that it occupies (eg. this could be in a situation where due to storm damage, the tree is no longer viable and may be a danger to life) to correct choice. In contrast, a tree may provide a special feature within its environment, which, if removed, would render the landscape bare of character and is therefore assigned the highest value Unit value factor The unit value factor is the conversion of the equation to a monetary value taking into account inflation and shall be determined from the mean of three separate wholesale valuations of the most commonly available 5 litre nursery stock tree and shall be rounded down to the nearest dollar. The source of valuation shall be taken in the capital city of the State or Territory in which the valuation is to be performed. 3.3 Substitute Assessment Trees Less Than Five Years Old Where a tree is less than five years old, or the valuation is less than the replacement cost, then the assessed value shall be deemed to be the replacement cost of equivalent advanced nursery stock plus delivery, planting, installation and 12 months establishment costs. 3.4 Replicate Assessment Where replicate valuations are required and agreed to by arrangement, the valuation shall be expressed as the mean value. Page 11 of 17

12 4. CALCULATION 4.1 Introduction The valuation of a tree shall be determined using the following equation in accordance with table 2.1 Value = Da (LCH + FYVS) Where: Value = Valuation of a tree in dollars (to the nearest dollar) Da = Unit Value Factor L = Visual impact value F = Frequency of occurrence value H = Historical significance value V = Form and vigour S = Live crown size value Y = Life expectancy value C = Site suitability value Page 12 of 17

13 PROPOSED STREET TREE PLANTING 2009 / 2010 High Street Continued planting of larger street trees to replace the ageing Elms. APPENDIX 2 Highett Street 1. Planting of both large and medium sized street trees to replace ageing trees. These trees will be planted in the centre of the nature strip to avoid damage to roads and drains and maximise the trees capacity to catch water. 2. Planting on Nature strips between plum trees for removal of plums in the future. Avenue Maroondah Highway / Midland Link Planting of large trees to replace ageing trees and beautify Mansfield entrance. Page 13 of 17

14 PROPOSED PLANTING POSITIONS RED = BLUE = Large street tree Medium street tree High Street Highett Street Page 14 of 17

15 Highett Street Page 15 of 17

16 PROPOSED TREE SPECIES The following trees are proposed for the Mansfield township in the near future. This does not exclude the planting of other species, or include future plantings or landscaping plans for other areas of the shire. Future landscaping/ planting projects in other Mansfield Shire towns should be developed separately and designed on its own merits. Pin Oak (Quercus palustris) Large tree up to 15 metres high. Has been used successfully around Mansfield shire with both young and old examples to be seen. Provides great shade. Golden Ash (Frazinus excelsior) Medium to large tree growing 7 metres high, provides great autumn colour and can handle dry conditions. Cimmzam Ash (Fraxinus excelsior) Large tree 13 metres high, reported to be tolerant to urban conditions, Holds foliage longer and gives great red colour in autumn. Page 16 of 17

17 Callistemon ( numerous varieties ) Strong native tree being used increasingly as a street tree. Many varieties could suit Mansfield streescape. Crepe Myrtle ( Lagerstromia indica ) Smallish tree to 3 metres high, gives orange / red colour in autumn, suitable for smaller areas and avenues. All images in Appendix 2 courtesy of Flemming s Trees Page 17 of 17