Are
Native Trees Always the Best Choices?
by Michael Kuhns, Extension Forestry Specialist
Across the country people are becoming interested in using native
plants in their landscapes, or in maintaining native landscapes
as they build homes or businesses. This is leading to problems,
however, as people plant inappropriate trees due to a false notion
of what "native" means, good well-adapted trees that are
non-native get overlooked, and homes built in existing native landscapes
are subjected to dangerous fires.
The roots of this native plant trend are in the renewed interest
in the environment that has come about over the last several years.
Plant-people in educational institutions, nurseries, garden centers,
and horticultural societies are also advocating the use of locally-adapted
native plants. This makes sense because these plants often require
lower inputs of water, minerals, and pesticides than exotic plants.
In
the Intermountain West this native plant trend is also taking hold.
For example, interest in xeriscaping, often incorporating native
plants, is increasing as people become more concerned about limited
water supplies. The increased interest in all types of native plants
has of course increased interest in landscaping with trees native
to our region.
The concept and practice of using native trees in home and business
landscapes in our region has some problems. By definition, a "native"
plant is one that is living, growing, and reproducing naturally
in a particular region. The key idea here is how we define a region.
Quaking aspen (Populus tremuloides) and singleleaf pinyon
(Pinus monophylla) are trees that are native to the region
we call the Great Basin or Intermountain West. However, each grows
in a much different habitat, with aspen found on higher wetter sites
in the mountains, and singleleaf pinyon growing at lower elevations
with very little moisture.
Simple acceptance of the idea of planting native trees would lead
to either of these species being planted anywhere in the region.
This obviously is not appropriate, however, since aspen planted
on a dry site where little supplemental moisture is available will
die. And planting of pinyon on naturally wet sites or sites where
we water heavily will also lead to failure. The focus in using native
trees should be on trees that are native to the region and that
are well-adapted to the specific site where they will be planted.
This of course means that native trees aren't even an option for
the sites where most people in our region live, since most of us
live at the bases of the mountains on sites where there never were
native trees. The fact that we can see aspens on the cool, moist
mountainsides from our kitchen windows in the dry, hot valley doesn't
mean that planting aspens in our yards is appropriate. And, in fact,
aspens tend not to do very well in many of the places where we live
because of the un-natural stresses they experience.
So, if we live on what is naturally semi-desert shrubland does
this mean that our landscape should consist of plants native to
such areas? If we care about the environment must we forget about
having trees for shade and wind protection since trees aren't native
for many of us? This is partly a philosophical question you need
to answer for yourself, but practically speaking there are some
environmentally responsible alternatives.
If we want trees in our naturally treeless landscapes then we need
to pick natives from our region that are appropriate for specific
planting sites. I think it also makes sense to consider the use
of locally-proven non-natives such as bur oak (Quercus macrocarpa)
and hackberry (Celtis occidentalis) that can help accomplish
the goals of reducing maintenance and inputs while having a desirable
landscape. Any use of non-natives must be done with care, of course,
to avoid the introduction of aggressive species that can become
pests like tamarisk (Tamarix spp.) and Russian-olive (Elaeagnus
angustifolia).
Problems are also associated with saving native trees when we build
into wooded areas. Construction activities often kill native plants
directly, and landscape maintenance practices such as establishing
well-watered bluegrass around drought-tolerant pinyon or juniper
trees can kill indirectly.
Many western forests are naturally adapted to regular fires that
clean out dead material, kill competing plants, or even kill all
trees and make way for a new forest. Examples are coniferous forests,
oak-maple woodlands, and pinyon-juniper woodlands. Many of the most
desirable homesites in our region are in such forests. Saving the
native vegetation may seem desirable, but homes and lives are likely
to be lost when these areas burn.
Firewise landscaping, where plant fuels and other landscape elements
are designed and managed with fire in mind, and proper construction
techniques and home placement can reduce fire hazards in such areas.
Ultimately, though, we may find that the risks and costs to society
of developing some of these areas are unacceptable.
For information on obtaining a Utah Tree Browser CD, with text
descriptions and color pictures to help you select a tree that is
right for your site, including every Utah native trees, click
here.
|