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→Plant Characteristics
==Plant Characteristics==
==Plant Characteristics==
===Soil Moisture===
===Soil Moisture===
Plant species are adapted to specific levels of moisture to achieve establishment and sustained growth. Soil moisture has been characterized by three categories: dry (1), moist (2) and wet (3). Some plants can tolerate a wide range of moisture regimes, whereas others perform optimally in a more narrow range of soil moisture conditions. Species ranked with a dash between two numbers can tolerate a range of conditions.
Plant species are adapted to specific levels of moisture to achieve establishment and sustained growth. Soil moisture has been characterized by three categories: dry (1), moist (2) and wet (3). Some plants can tolerate a wide range of moisture regimes, whereas others perform optimally in a more narrow range of soil moisture conditions. Species ranked with a dash between two numbers can tolerate a range of conditions.
===Partial Shade Tolerance===
===Partial Shade Tolerance===
Plant species react differently to varying levels of sunlight and shade. Plant adaptations to these parameters are referred to in terms of degree of exposure. Most of the LID practices will be installed in newly developed areas, thereby providing exposure to full sun, meaning at least 6 full hours of direct sunlight for plantings. As trees develop over several years, or if an LID practice is installed in an area where there are existing trees or buildings providing partial shade, plants adapted to 3 to 6 hours of sunlight exposure should be used. Plants tolerant of full shade require less than 3 hours of direct sunlight each day. However, some shade-adapted species come into leaf early in the growing season in order to take advantage of full sunlight before tree leaves emerge and create shade.
Plant species react differently to varying levels of sunlight and shade. Plant adaptations to these parameters are referred to in terms of degree of exposure. Most of the LID practices will be installed in newly developed areas, thereby providing exposure to full sun, meaning at least 6 full hours of direct sunlight for plantings. As trees develop over several years, or if an LID practice is installed in an area where there are existing trees or buildings providing partial shade, plants adapted to 3 to 6 hours of sunlight exposure should be used. Plants tolerant of full shade require less than 3 hours of direct sunlight each day. However, some shade-adapted species come into leaf early in the growing season in order to take advantage of full sunlight before tree leaves emerge and create shade.
===Drought Tolerance===
===Drought Tolerance===
These categories represent broad generalisations regarding drought tolerance.
These categories represent broad generalizations regarding drought tolerance.
===Salt tolerance===
===Salt tolerance===
The low, medium and high categories indicate the tolerance of plant species to [[salt]] exposure and/or uptake. Plant species with low salt tolerance should not be used in any LID practice receiving runoff from salted roads and parking lots. Species with medium salt tolerance can be utilised in LID practices that will be receiving road runoff but should not be in the line of salt spray or be receiving the bulk of the runoff. Species with high salt tolerance should be planted in LID practices that receive road or parking lot runoff that routinely contains road salt. Few plants are truly halophytic or “salt-loving”. In most cases, elevated salt levels are temporary and precipitation quickly dilutes and removes salt from the soil profile. The plant lists below include recommended species for LID practices likely to receive road or parking lot runoff.
The low, medium and high categories indicate the tolerance of plant species to [[salt]] exposure and/or uptake. Plant species with low salt tolerance should not be used in any LID practice receiving runoff from salted roads and parking lots. Species with medium salt tolerance can be utilised in LID practices that will be receiving road runoff but should not be in the line of salt spray or be receiving the bulk of the runoff. Species with high salt tolerance should be planted in LID practices that receive road or parking lot runoff that routinely contains road salt. Few plants are truly halophytic or “salt-loving”. In most cases, elevated salt levels are temporary and precipitation quickly dilutes and removes salt from the soil profile. The plant lists below include recommended species for LID practices likely to receive road or parking lot runoff.
===Pollution and Compaction Tolerance===
===Pollution and Compaction Tolerance===
Development nearly always causes compaction of on-site soil, and bioretention facilities in road-right-of-ways should be pollution tolerant.
Development nearly always causes compaction of on-site soil, and bioretention facilities in road-right-of-ways should be pollution tolerant.
===STEP Stars===
===STEP Stars===
These are species which have demonstrated good performance in projects designed, installed and monitored by the Sustainable Technologies Evaluation Program.
These are species which have demonstrated good performance in projects designed, installed and monitored by the Sustainable Technologies Evaluation Program.
{| class="wikitable"
|+ Advanced plant selection criteria
|-
!Plant characteristic
!Potential benefit to LID performance
|-
|Plant mass
|Higher biomass consumes more [[nutrients]] (decreases nutrient discharge from bioretention) and increases [[transpiration]] rate.
|-
|Growth rate
|Higher growth rate consumes more nutrients, particularly in combination with root characteristics as below.
|-
|Root lipid content
|Higher root lipids have been associated with increased plant uptake of organic contaminants such as polyaromatic hydrocarbons (PAHs)
|-
|Root length
|Longer roots are associated with plants consuming more nutrients, although roots which reach the bottom to the media may contribute nutrient...
|-
|Root mass and thickness
|Larger overall root mass and many dense fine roots are associated with increased nutrient uptake by plants. Thicker roots help to preserve hydraulic conductivity of the media.
|-
|High-nutrient tolerance
|Plants adapted to high nutrient environments are likely to uptake nutrients at a higher rate.
|}
==See Also==
==See Also==