Species selected for ignition testing and fire behaviour for use along right of ways

Introduction

Planting less flammable species along right-of-ways to minimise the potential for fire ignitions or fire spread in Alberta is an idea that has recently garnered attention in the fire community. The use of such plants to reduce the effects of fire is not a new idea. It has been tested in Australia, New Zealand, the USA and research has been carried out in Ontario for Bell Canada and CP Rail.

Fires involving linear disturbances in Alberta are seasonal in nature and the primary fire carrying fuel is grass. Grasses are capable of igniting easily and carrying fire at a high rate of spread while in a cured condition. Grass is in a cured state during the spring and fall, and with Alberta’s springs tending to be dry and windy, the conditions generally exist for grass fires immediately following snowmelt. Over the last five or six years Alberta has experienced a number of large and challenging fires where linear disturbances played a role in the problems encountered in trying to control these fires. These recent occurrences have led to an interest in the linear disturbance project and in the use of less-flammable vegetation in areas in close proximity to values at risk or other tactical areas to minimise the affect of fire.

 

Characteristics of Desirable Species

There are a number of characteristics that less-flammable species have that make them desirable for use. There are also restrictions on what species can be used in different locations of the province. Alberta’s Ministry of Environment and Sustainable Resource Development (SRD) have strict regulations on the use of introduced species in the province. These have to be followed when a species is chosen for testing.

There are many species adapted to fire and these tend to have similar physical characteristics. Past research has studied these characteristics and the important traits seem to be:

1.      stem density
2.      radius
3.      surface area to volume ratio
4.      moisture content (Hogenbirk 1996)

These traits were measured to determine a relationship between them and plant ignitability. Surprisingly, moisture content was rated the fourth most important variable.

Hogenbirk (1996) compiled a list of characteristics of the ideal species for ‘greenstripping’. Greenstripping is used to mean the use of less-flammable plants to reduce fire hazard’

These plants should:

·        reduce the probability of ignition throughout the year
·        Reduce fire spread rates
·        Remain dominant on a site for 10+ years
·        Create no additional environmental or safety hazards

The plants should also:

·        Grow quickly in the spring
·        Maintain high moisture content
·        Be low growing
·        Produce small quantities of dead standing crop
·        Produce small amounts of litter
·        Litter should decompose quickly
·        Out-compete other plants
·        Re-establish dominance following disturbance
·        Be cost-effective

The literature was searched for plants native to Alberta that meet these criteria and a few have been chosen for possible testing. These will be described and presented for discussion in the fire community. Comments are appreciated. The objective of this search is to determine a number of species for testing. Plots will be set up with the chosen group and ignition testing and fire behaviour tests will be performed on them at different times of the year.

The research into species flammability will take place with the Alberta Research Council (ARC) in Vegreville, Alberta. ARC has the expertise and resources to establish, grow and maintain the plots. Test plots will be established and planted in the spring of 2005 and plans are to perform ignition testing and fire behaviour tests in the spring and fall of 2006.

 

Species selected for potential testing

Forb/herb species

1.      Fireweed

Fireweed has been cited by a number of studies as a fire resistant plant. There are many characteristics of fireweed that make it a species that should be considered seriously. First of all it is native to Alberta and is known for its ability to recolonize a site following disturbance; this is important considering we are dealing with disturbed sites.

Fireweed is a fast growing species that is able to dominate a site for a number of years before it is replaced by other successional species. It grows quickly in the spring and due to it’s dense growing habit it shades the ground which acts to keep moisture contents high in relation to other surface fuels. In one study, fireweed had the lowest ignitability of species tested. It also provides cover to a number of smaller animals and some larger mammals. The species is widely available and the seeds are easily collected. Fireweed does tolerate drought conditions. Fireweed produces minor amounts of litter.

Height – can grow to 2.0 m in Alberta, but does not generally attain this height.

 

2.      Alsike Clover

Clover as a species is known to retard fire spread. One of the main advantages of clover is that it greens up very quickly during the spring, even at low temperatures and it stays green through the fall. Clovers are able to dominate an area. Alsike clover can dominate an area for a couple of years and exist in a site for an extended period of time. Clovers are used widely for reclamation at this time and it provides abundant food for mammals.

Height – from 20-80 cm in height (generally shorter). Alsike clover has moderate tolerance to drought.

 

3.      White Clover

White clover is slightly different than Alsike clover and is also a species that should be tested. It is a low creeping species commonly occurring in lawns that is a moderately aggressive species. It has intermediate spring growth. It also provides food to mammals. Seed is available for this species. White clover is presently used for corridor reclamation on seismic and pipeline rights-of-way in Alberta.

 

4.      Common Yarrow

Yarrow is believed to be able to reduce fire hazard due to its physical characteristics, but is unable to resist invasion from other species. This species may have to be planted in combination with another species that is able to resist invasion for it to work effectively. It does not dominate an area but is common along linear disturbances. It has low spring height but rapid spring growth, but if it is green this should not cause a concern. It provides abundant shade during the spring to keep moisture content high during this season. Related species have been tested in the US.

 

Other Species (thought to offer less potential)

5.      Pearly Everlasting (forb)

Pearly everlasting is a forb that has rapid spring growth and covers a high area based on its biomass. The only drawback to this species is that it is not too common a species in Alberta. In one study it had a long time-to-ignition for both live and dead stems.

 

Grasses

6.      Crested Wheatgrass

This species was selected because it compliments the clover. It can be grown in combination with clover to dominate and area. It is a clump grass and therefore there is space between the clumps. This spacing can act to slow fire spread. It can be mixed with clover easily and this combination should retard fire spread. This is a medium height bunchgrass (~ 40 cm) that has a high tolerance to drought. It can be planted all through Alberta.

 

Image from: Dave Powell, USDA Forest Service, www.forestryimages.org

7.      Sheep Fescue

This is a low growing densely tufted grass that is adapted to most locations in Alberta. It has good compatibility with other plants and will be tested with the clover. The primary reason it has been selected for trial is it’s low growing nature. A shorter grass species would decrease a fires’ intensity when compared to a taller, thick growing species.