ANSI A300 standards provide requirements and recommendations for accepted tree care practices and guidelines for writing work specifications. ANSI A300 standards unify and take authoritative precedence over all previously existing tree care industry standards in USA.
In 2013 the Davey Resource Group created a "Five-Year Tree Management Solutions for University of Nevada, Reno." This document inventories the more than 3000 trees on campus and lays out a 5-year maintenance plan, which we follow. We use TreeKeeper 7 software to track and schedule maintenance on individual trees. Below is a list of general policies for campus tree care.
1:1 No trees will be planted smaller than 1.5" caliper.
1:2 No shrubs will be planted smaller than 5 gallon. 1 gallon can be used after approval from Owner.
1:3 All plant material shall meet the current industrial standards adopted by the American Association of Nurseryman ANSI Z60 Standards and NRS 555.
1:4 All plant material shall be inspected by Owner at the nursery if possible, before delivery to campus and installation.
1:5 Contractor shall Guarantee all plant material for one year after final Inspection.
1:6 Contractor shall maintain all plant material in a healthy condition for 90 days after final inspection.
1:7 Contractor shall be responsible for programming the controller and irrigating all plant material until the end of the 90 day maintenance period including valve maintenance, pipe repair, and head adjustment.
1:8 The owner reserves the right to adjust the plant plan prior to installation.
1:9 Excavate plant holes 3 - 5 times as wide as ball diameter and deep enough to allow placing the root ball in the same relation to finished grade that it has in the container or burlap ball. Hole should be shaped like a bowl, narrow at the base and wide at the top (not shaped like a cylinder). Allow top of root ball and bottom of root flare to extend 2 - 3" above grade in native soil; plant at grade for prepared soil 18" deep. Gradually mound soil up to top of root ball and place earthen ring around edge of root ball.
Add mulch 2 - 3" on ring, but only 1/2" on top of root ball or none at all. Never pile mulch up around trunk of tree. Leave a 10 inch radius from trunk of tree.
1:10 Rock or bark mulch shall be utilized in all non-turf areas. Bark mulch shall be 2 - 3" deep throughout. Mulch should be raked flat and even - no piles or lumps. Rock areas shall include a landscape fabric.
1:11 Cornell Structural Soil Mix shall be utilized under all hard surfaces where trees are to be planted in tree wells surrounded by concrete, pavers, or asphalt. CU Structural Soil Link. Then type "Outreach>Structural Soil" in the Search Box at the top.
1:12 Tree ball and burlap root ball diameter shall be 12" for every 1" of trunk diameter.
1:13 Should there be a discrepancy between the American Association of Nurserymen Standards and UNR Standards, UNR standards shall prevail.
1:14 The contractor will notify owners representative to approve plant placement before the planting of all trees, shrubs, & turf.
1:15 Plants with girdling roots will not be accepted and will subject the entire delivery to rejection. 1:16 Trees that have been grown tied directly to stakes will not be accepted.
1:17 Trees and shrubs stored on site shall have their containers or root balls protected from direct sun light by contractor. For balled and burlap (B & B) trees, heel in and cover with mulch up to top of root ball. Group trees together to prevent wind from blowing them over.
1:18 Trees and shrubs stored on site shall be watered frequently to keep uniform moisture, daily if necessary. Adjust per climatic conditions.
1:19 Do not install plants when the ground is frozen.
1:20 Install plant material plumb and in the center of pit slightly above adjacent grade. 1:21 Do not prune any plant material without authorization from owner's representative.
1:22 All plant substitutions shall be submitted to owner for approval before award of contract.
1:23 Container plants with densely swirling rigid roots inside the container surface will not be accepted. 1:24 Construction documents shall be on site at all times until final acceptance.
1:25 A competent supervisor shall be on site at all times until completion of landscape installation.
1:26 There shall be a pre-construction meeting with owner's representative before construction begins. 1:27 All trees planted in areas other than lawn shall be irrigated on a separate zone from shrubs.
Exceptions allowed only with approval of owner.
- Existing trees shall be preserved where Tree stacking method to be reviewed with Owner.
- Contractor to submit landscape protection and watering plan, and schedule to
- Landscape design shall minimize water use and
- Water conserving native plant materials shall be used to the greatest extent
- Grading, dust control, weed control, curbs, gutters, streets, off-street parking and sidewalks shall conform to local ordinances and local design and site construction standards.
- Site development shall give full consideration to established flood plains, and existing easements and right-of-ways.
MAINTENANCE AND REMOVAL
(refer to ANSI 300 standards)
The canopy of a tree occasionally becomes so dense that the canopy needs to be thinned. Thinning is the removal of lateral branches at their point of origin or the shortening of a branch or stem by cutting a lateral large enough to assume the terminal role. There are several reasons for thinning a tree. Trees may need to be thinned to minimize storm damage of to allow better air circulation to reduce disease problems. Trees may be thinned as a bird control measure to create a less desirable roosting site. More commonly, trees are usually thinned to allow additional light to reach plants growing beneath the canopy.
- Raising limbs:
Raising limbs or crown raising, is the removal of the lower branches of a tree in order to provide clearance. There are several reasons for raising the crown of a tree. Unobstructed visibility is necessary to improve the security and safety of the campus. Along streets and parking lots, it is imperative that the trees have the appropriate clearance of 14 ft. 6in. for vehicular traffic. Pedestrian walkways will not exceed 7 ft. unless special circumstances permit.
Throughout the life of a tree, it is a normal process for some branches in the canopy to die while new branches are being created. Other branches die due to the affect of disease of other stress factors. In a managed urban forest, trees periodically need to crown cleaning to remove dead, diseased and dying branches. Beside the aesthetic benefits, trees should have deadwood removed to improve the health of the tree and to remove potential hazards for the university community. This is especially important for deadwood larger than four inches, which could cause serious injury to people and property.
Like all life on earth, trees eventually decline and die. Studies have shown that due to the multiple stresses that exist in the urban environment, trees have a greatly reduced life span. In most cases, these trees cannot be remedied and must be removed. There are two primary reasons for removing a tree: aesthetics and safety. When a tree declines into poor condition, it has exceeded its useful life and should be removed so that it can be replaced with a vigorous healthy tree. In many cases, a tree, regardless of aesthetic appearance, poses a threat to people and property and must be removed.
- Broken branches:
Broken branches are a common occurrence caused by the action of wind, machinery, precipitation, or other factor. Many of these branches fail because of poor tree structure of weak wood. In any case, these branches must be removed because of the liability that they pose to the university community.
- Training pruning:
Trees that need training, pruning are smaller trees, and in some cases larger trees, that need to be pruned to direct future growth. These trees have either existing or potential problems with poor branch attachment, interfering or crossing branches, watersprouts, or weak branches. These trees need to be pruned or shaped to direct future growth. The result of this type of pruning is a more beautiful and structurally sound tree and a significant reduction in future maintenance costs.
Cabling and bracing is the art and science of using cables and/or wood screws (braces) to repair or prolong the usefulness of a tree. Cables are commonly used to help support weak branches, to help straighten trees and to minimize canopy movement to reduce wind damage. Braces are usually used in combination with cables to help stabilize of pull split trunks back together. Cabling and bracing should not be used to correct hazardous tree problems, but they can be useful in prolonging the life of a significant tree.
- Cavity filling:
Trees suffer mechanical damage from a number of sources including landscape maintenance equipment, vehicles, the environment and other factors. Many times, trunk wounds are invaded by biological organisms that degrade the woody tissues of the tree resulting in cavities in the trunk. Cavities can be hidden within the trunk, or they can be exposed to the surface leaving a small or large open hole. It becomes difficult or impossible for the tree to grow across the expanse and repair the damage, so it sometimes becomes necessary to fill the cavity so that callus can grow across the hole and close off the cavity to the outside.
- Stump grinding:
Stumps are the consequence of tree removal. Stumps detract from the aesthetic appearance of the campus and can create safety hazards. Stumps also affect other landscape maintenance activities by creating an obstacle that has to be mowed around. Stumps are removed by using a machine to grind the stumps below the soil surface.
Continual removal of leaf debris around a tree eventually results in a loss of valuable nutrients that would normally be available to a tree in a natural forest. For this reason, trees in a urban forest need to be supplemented with additional nutrients. This usually involves injecting a soluble, slow-release fertilizer into the soil so that it can be taken up by the root system. Mulching around the trees is also important for returning nutrients to the soil.
Occasionally, trees are attacked by various insects and microorganisms and must be treated to protect them from disease. This usually involves spraying them with a pesticide or in the case of birches the trees are injected with a pesticide.
- Soil amending:
Biostimulants and Mycorrhizal fungi are incorporated into the soil profile near the root system of the tree to improve health and vigor.
PLANT SELECTION GUIDELINES
- The University prioritizes water-conserving landscape design that requires minimal maintenance.
- Because the University campus is a designated arboretum, it features a diversity of plants, including non-native species and drought-intolerant varieties.
- Introduction of new or unusual plant species needs to be approved by the university landscape manager who may consult with the Arboretum Board.
- The university arboretum contains edible plants such as fruit trees, berry bushes, and herbs as ornamentals, but they were not planted for use as a food source, and new edible plants are not being added to the landscaping.
- Poisonous plants are not used near water, dining establishments, and children’s facilities.
- University Facilities maintains a list of plants that should not to be used on campus because they are noxious, invasive, or poisonous.
- Detailed and updated landscape design guidance is provided in the University’s Design and Construction Standards.
MANAGING FOR CATASTROPHIC EVENTS
Facilities has a Weather Essential team that assembles in the case of minor damage from high winds, floods, earthquakes, heavy snows, and fires. This team manages the clean-‐up and removal of any damaged trees and/or debris and also contracts tree removal services.
If the situation in catastrophic an Incident Command Team is assembled and works with local emergency response teams. The University has practice drills to train staff.