Revised Arborist Report 300 Montague Expressway Milpitas, CA Prepared for: Trumark Companies 4185 Blackhawk Plaza Circle, Suite 200 Danville, CA 94506 Prepared by: HortScience, Inc. 2150 Rheem Dr., Suite A Pleasanton, CA 94588 October, 2011 Revised Arborist Report 300 Montague Expressway Milpitas Table of Contents Page Introduction and Overview 1 Survey Methods 1 Description of Trees 2 Suitability for Preservation 4 Evaluation of Impacts 5 Tree Preservation Guidelines 7 List of Tables Table 1. Tree condition and frequency of occurrence 3 Table 2. Suitability for Preservation 5 Table 3. Recommendations for preservation 6 Attachments Tree Assessment Form Tree Assessment Map Revised Arborist Report, Trumark Companies HortScience, Inc. 300 Montague Expressway, Milpitas Page 1 Introduction and Overview Trumark Companies are proposing to redevelop the property located at 300 Montague Expressway, in Milpitas. The site is triangular, bordered by Montague Expressway to the west and Trade Zone Blvd. to the south. Currently, the site is an office complex, with a vegetated berm along the western and southern boundaries. The three buildings are centrally located with peripheral parking and landscaping throughout. The plan proposes to construct 92 attached town homes and 42 single-family homes, for a total of 134 homes. HortScience, Inc. was asked to prepare an Arborist Report for the site. This report provides the following information: 1. An evaluation of the health and structural condition of all trees growing within and adjacent to the project area based on a visual inspection of external conditions. 2. An assessment of the impacts of constructing the proposed project on the trees. 3. Guidelines for tree preservation during the design, construction and maintenance phases of development. Assessment Methods Trees were surveyed on June 7, 2011. All trees with diameters of 4” or greater were included (per City of Milpitas Municipal Ordinance X-2-7.01-1). The survey procedure consisted of the following steps: 1. Identifying the tree as to species; 2. Tagging each tree with a metal tag and recording its location on a map; 3. Measuring the trunk diameter at a point 24” above grade; 4. Evaluating the health and structural condition using a scale of 0 – 5: 5 - A healthy, vigorous tree, reasonably free of signs and symptoms of disease, with good structure and form typical of the species. 4 - Tree with slight decline in vigor, small amount of twig dieback, minor structural defects that could be corrected. 3 - Tree with moderate vigor, moderate twig and small branch dieback, thinning of crown, poor leaf color, moderate structural defects that might be mitigated with regular care. 2 - Tree in decline, epicormic growth, extensive dieback of medium to large branches, significant structural defects that cannot be abated. 1 - Tree in severe decline, dieback of scaffold branches and/or trunk; most of foliage from epicormics; extensive structural defects that cannot be abated. 0 – Dead. 5. Rating the suitability for preservation as “good”, “moderate” or “poor”. Suitability for preservation considers the health, age and structural condition of the tree species, and its potential to remain an asset to the site for years to come. Good: Trees with good health and structural stability that have the potential for longevity at the site. Moderate: Trees with somewhat declining health and/or structural defects than can be abated with treatment. The tree will require more intense management and monitoring, and may have shorter life span than those in ‘good’ category. Poor: Trees in poor health or with significant structural defects that cannot be mitigated. Tree is expected to continue to decline, regardless of treatment. The species or individual tree may have characteristics that are undesirable for landscapes, and generally are unsuited for use areas. Revised Arborist Report, Trumark Companies HortScience, Inc. 300 Montague Expressway, Milpitas Page 2 Description of Trees One hundred and ninety-three (193) trees, representing 12 species, were assessed. Descriptions of each tree are provided in the Tree Assessment Forms and locations are shown on the Tree Assessment Map (see Attachments). Trees were in two distinct groups. Eighty-three (83) trees were concentrated on the periphery, with London plane and evergreen ash planted on the earthen berm along Trade Zone Blvd., and camphor and evergreen ash planted on the earthen berm along Montague Expressway. One-hundred ten (110) trees had been planted in the interior of the site around buildings and in the parking lots. These were a mix of mature coast redwoods and young white birch, white alder, Southern magnolia and flowering cherry. The most frequently occurring species was coast redwood, with 37 trees or 19% of the population (Table 1, following page). Twenty-four (24) of these were mature, with diameters between 24” and 38”. Twenty-six (26), or 70%, were in good condition, 11 in fair and none in poor. Twenty-one (21) of the coast redwoods were noted as having some amount of thinning in the canopy (Photo 1, following page. This condition is reversible and is typically associated with inadequate summertime irrigation. Camphor, with 30 trees (15%), was the second most commonly surveyed tree. They had been planted exclusively on the berm along Montague Expressway and had not performed as well as other species at the site. Four (4) were in good condition, 18 in fair, and eight (8) in poor. Many had extensive dieback of twigs and branches and poor color. All but four (4) of the camphors were young, with diameters of 12” or less. Three additional species were also well represented at the site: London plane, with 29 trees (15%), had been planted along the berm on Trade Zone Blvd. The species had performed very well, with 24 in good condition, five (5) in fair, and none in poor. Many of the trees leaned slightly to the south, presumably in response to the prevailing wind direction. Anthracnose, an annual fungal pathogen which often kills the first set of leaves, was common among the London planes at the site. The species tolerates the pathogen, pushing out a second set of leaves every year. Evergreen ash had been planted across the site, with 20 growing on the berms along Montague Expressway and Trade Zone Blvd., and the remaining eight (8) planted in small parking lot islands. Sixteen (16) were in good condition, six (6) fair and six (6) poor. Where the species had been planted in the parking lot islands, it had commonly displaced the adjacent hardscape. Twenty-seven (27) white birch had been planted exclusively on the interior of the site, adjacent to buildings. Thirteen (13) were in good condition, eight (8) fair, five (5) poor and one (1) was dead. The species is riparian and is typically associated with flowing water. Many of the trees had dieback varying from minor to extensive. Tree size ranged from 4” to 38” in diameter for single-trunked trees. Only four (4) of the trees were multi-trunked. The majority of the trees (92 trees or 48%) were in good condition (Table 1, following page). Thirty-eight percent (73 trees) were in fair condition, 13% (26 trees) were rated in poor condition, and 1% (2 trees) were dead. The City of Milpitas defines any tree with a circumference of 37” (diameter of 12”) or greater on developed commercial or industrial property as “Protected” (Street Tree Ordinance X-2-7.01-1). One hundred and twenty-five (125) trees met the criteria for “Protected” status. “Protected” trees are identified in the Tree Assessment Form (see attachments). Revised Arborist Report, Trumark Companies HortScience, Inc. 300 Montague Expressway, Milpitas Page 3 Photo 1: Looking south at coast redwoods #60-62. All three were in fair condition, with ‘very thin crowns’. Tinning crowns in coast redwood is often associated with a lack of adequate summertime irrigation, but is reversible. The condition is more often associated with mature trees, which require more water, or those located in hot inland locations, well away from the cool, foggy coast where the species is native. Table 1. Tree condition & frequency of occurrence. 300 Montague Expressway, Milpitas Common Name Scientific Name Condition Rating No. of Dead Poor Fair Good trees (0) (1-2) (3) (4-5) White alder Alnus rhombifolia 1 1 5 1 9 White birch Betula pendula 1 5 8 13 27 Camphor Cinnamomum camphora - 8 18 4 30 Nichol’s gum Eucalyptus nicholii - - 2 1 3 Evergreen ash Fraxinus uhdei - 6 6 16 28 Sweetgum Liquidambar styraciflua - 1 2 2 5 Southern magnolia Magnolia grandiflora - - 8 1 9 London plane Platanus x acerifolia - - 5 24 29 African fern pine Podocarpus gracilor - 1 1 2 4 Flowering cherry Prunus serrulata - 3 6 2 11 Coast redwood Sequoia sempervirens - - 11 26 37 Siberian elm Ulmus pumila - - 1 - 1 Total 2 26 73 92 193 1% 13% 38% 48% 100% Revised Arborist Report, Trumark Companies HortScience, Inc. 300 Montague Expressway, Milpitas Page 4 Suitability for Preservation Before evaluating the impacts that will occur during development, it is important to consider the quality of the tree resource itself, and the potential for individual trees to function well over an extended length of time. Trees that are preserved on development sites must be carefully selected to make sure that they may survive development impacts, adapt to a new environment and perform well in the landscape. For trees growing in open fields, away from areas where people and property are present, structural defects and/or poor health presents a low risk of damage or injury if they fail. However, we must be concerned about safety in use areas. Therefore, where development encroaches into existing plantings, we must consider their structural stability as well as their potential to grow and thrive in a new environment.