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Woodland NOTES
- Vol.17, No. 1, Fall/Winter, 2005-2006
In this issue:
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Best Management Practices (BMP’s) for Idaho Riparian Areas.
Yvonne Barkley
 Idaho’s
forested land provides us with clean water and air, wildlife habitat,
timber, multiple recreational opportunities, and beauty beyond compare.
The practice of forestry has been described as being both an art and a
science and those who own and manage forestland know this to be true.
Some things can be measured, calculated, predicted, and formulated,
while other things cannot - we can only forecast the weather, estimate
growth, and predict forest health conditions. When it comes to forest
management, one of the things we do know for sure is that "it depends".
What happens in a forested ecosystem so often depends on past uses,
current conditions, and future decisions. It depends on how much
moisture we get and when, on dry lightening and fuel conditions, on
soils, nutrients, and species compositions. As with other land
management decisions and outcomes, in forestry "it depends".
But forestry is also a science. We have come a long way in
understanding forested ecosystems. We have found our way through
research and trial and error. And we are always learning something new.
Best Management Practices (BMP’s) were developed as recommendations for
Idaho’s forest owners and managers to follow, not only to comply with
the Idaho Forest Practices Act, but also to enable us to be better land
managers and stewards. BMP’s have been determined to be the most
effective and practicable means of preventing or reducing the amount of
non-point pollution generated by forest practices. BMP’s apply to all
aspects of forest management – road planning, design, construction, and
maintenance, timber harvest planning and execution, and streamside
management. This article addresses BMP’s in riparian areas and stream
protection zones (SPZ’s).
Riparian areas are directly adjacent to bodies of water and have many
important functions. They act as a filter and effectively trap sediment
from entering stream environments from adjacent roads and uphill areas.
Trout and other fish reproduce by laying their eggs in stream-bottom
gravel. When too much sediment enters the stream environment, it fills
the gaps in the gravel and suffocates eggs and fry of reproducing
species. Excessive sediment also has an abrasive effect on sensitive
gill tissues, kills aquatic insects and algae, fills in resting pools,
and interferes with recreation.
 Riparian
areas provide shade to the stream environment. By maintaining
vegetation along streams, water temperatures remain more constant.
Without streamside vegetation, water temperatures would be higher in the
summer and lower in the winter. Aquatic species have a small temperature
and dissolved oxygen range in which they successively reproduce and
thrive. Warmer than average water temperatures decreases dissolves
oxygen, increases algae growth, and effects spawning behaviors and
success.
Vegetation along streambanks reduces bank degradation and provides
habitat to a multitude of wildlife species. Streambanks are stabilized
by the root systems of trees and shrubs that line the banks. Dense
vegetation slows water velocities, which is especially important during
flooding, and bank overhangs provide hiding places for fish where they
can rest and feed with less pressure from predators.
In the Northern Rockies, 59 percent of land birds use riparian areas
for breeding, 39 percent of which breed in no other habitats. Food and
cover are abundant in riparian areas, not only for land animals, but
also for those that live in the stream as well. Leaves and insects
dropping into streams from overhanging vegetation provide 90 percent of
the food that enters streams in forested environments. Dense riparian
vegetation also serves as well-traveled wildlife corridors that connect
one area with another.
Stream Protection Zones (SPZ’s).
The Idaho Forest Practices Act (FPA) states that streambeds and
streamside vegetation shall be protected during and after forest
practice operations, leaving them in the most natural conditions as
possible to maintain water quality and aquatic habitats. To sum it up,
stream protection zones are meant to "keep the dirt out of the creek".
Forest owners and managers know that riparian areas often support the
best tree growth - trees respond to the deep fertile soils and moisture
available in riparian areas. But the SPZ does not have to be a timber
harvest "keep out" zone. With the right planning and execution, some
trees in the SPZ can be harvested without damaging riparian habitats and
other benefits of healthy riparian systems.
As defined by FPA, Class I streams are used for domestic water supply
or are important for the spawning, rearing, or mitigation of fish. Class
II streams are usually headwater streams or minor drainages that are
used by only a few, if any, fish for spawning and rearing. Streams do
not have to have water in them to be classified as streams by the state.
FPA defines a stream as "a natural water course of perceptible extent
with definite beds and banks which confines and conducts continuously or
intermittently flowing water. Definite beds are defined as having a
sandy or rocky bottom which results from the scouring action of water
flow." Any reference in the FPA rules to Class I streams also applies to
lakes.
Class I SPZ’s are a mandated 75-foot minimum slope distance on each
side of the ordinary high water marks. Class II SPZ’s are a mandated
30-foot minimum slope distance on each side of ordinary high water
marks. For Class II streams that do not contribute surface flow to Class
I streams must be treated to provide soil stabilization and water
filtering effects by leaving undisturbed soils in widths sufficient to
prevent washing of sediment. In no case will this width be less than
five feet slope distance on each side of the ordinary high water marks.
In addition:
- SPZ’s must extend beyond the
75-foot minimum when steep or erosive soils border the stream
corridor. The steeper the slope, the wider the SPZ.
- SPZ’s also extend beyond the
75-foot minimum when wetland areas lie adjacent to a stream.
Boundaries then need to loop out to include any wetlands in the SPZ.
- Lakes require an approved site
specific riparian management prescription prior to conducting forest
practices within the SPZ.
- SPZ’s boundaries should be clearly
marked with plastic flagging, paint, or signs.
- Equipment is not allowed in SPZ’s or wet areas, but harvesting is
allowed.
- When harvesting within a SPZ, leave 75 percent of current shade
cover adjacent to streams. This can be in the form of hardwoods,
unmechantable trees, and shrubs. You must also provide for large
organic debris, soil stabilization, wildlife cover, and water
filtering effects of vegetation.
- Directional falling and/or mechanical feller bunchers allow the
removal of some SPZ trees without damaging the SPZ. Avoid falling
trees into streams or water bodies.
- Suspend the lead end of the log when skidding trees out of the SPZ whenever possible. Ground based skidding in or through streams is
not permitted.
- Keep slash out of streams by limbing or topping trees above the
high water mark. Whole-tree or tree-length yarding can reduce slash
disposal in the SPZ.
- Hand-scalp and plant trees by hand in SPZ’s.
Best management practices are part of the tool kit provided to
forestland managers through research, trial, and error, that, when
applied correctly, allows us to practice the art and science of
forestry.
For more information on BMP’s, contact your Idaho Department of Lands
Forest Practices Advisor (listed in your phone book) or the UI Extension
Forestry office (208-885-7718) for a copy of the following publications:
- "Rules Pertaining to the Idaho Forest Practices Act, Title 38,
Chapter 13, Idaho Code"
- "Forestry BMP’s for Idaho".
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Wood for Wildlife
Chris Schnepf
When foresters talk about leaving organic debris, they often focus on
feeding forest soils, minimizing fire risk, and avoiding bark beetle
problems. But if they are looking at broader ecosystem functions, they
will also look at organic debris for wildlife. Many forest owners value
wildlife for their own sake, but even where management focus is
primarily on timber, wildlife can contribute to those objectives. For
example, the owls that use snags left on a site will prey on pocket
gophers – a chief nemesis of tree planters everywhere.
For the most part, wildlife biologists looking at organic debris
concentrate on material larger than 3 inches in diameter, known as
coarse woody debris (CWD). Slash (organic debris smaller than
3 inches in diameter) ultimately helps wildlife to the extent it
enriches forest soils, which in turn feeds the plants, trees, and fungi
that wildlife depend on. Slash piles may also shelter small mammals. But
inadequate coarse woody debris is often more limiting to wildlife.
Species ranging from bears to rubber boas use CWD for many purposes. For
example:
- both birds and mammals use CWD as a place to forage
for insects or fungi;
- martens, fishers, bobcats, and black bears use CWD
for dens and shelter;
- many small mammals use CWD for hiding cover and
protection;
- small mammals also use logs as runways;
- many amphibians benefit from CWD because it
provides a cooler, moister habitats with more stable temperatures for
breeding and other activities;
- birds use CWD for lookout posts and reproductive
displays; and
- predators such as martens and weasels use CWD for
access under snow to their prey.
Managing CWD for forest nutrition is relatively straight-forward.
Determine how many tons of CWD you need per acre and when and how to
treat it to minimize insect and fire concerns. Managing CWD for wildlife
is more complicated. The size, distribution, and orientation of logs are
more important than sheer quantity. Also, different wildlife species
have different habitat needs, some of which may conflict. For example,
heavy log concentrations may be good for small mammals but limit elk
movement. Since many, if not most, wildlife species of interest cross
property boundaries, you also have to factor in what needs are being met
by nearby forests. More research is needed, but some general strategies
for managing CWD for wildlife can be grouped into three categories:
snags, size and characteristics, and arrangement.
 Snags. The
primary focus in this article is logs on the ground. But before a tree
can become log habitat, it must die. Sometimes green trees are blown
down by the wind and immediately provide CWD, but more commonly, the
dead trees remain standing for decades. This dead, standing tree is
called a snag. Snags are a valuable resource for a whole host of
wildlife species and are often the first thing that biologists look for
when evaluating forest wildlife habitat quality. For a good summary on
snags, read Managing Small Woodlands for Cavity Nesting Birds,
downloadable at
http://www.woodlandfishandwildlife.org.
Coarse Woody Debris Size and Characteristics. Wildlife
biologists often emphasize large pieces of organic debris for wildlife,
as they can benefit a wider range of species. For example, black bears
can den in the stump of a large windthrown tree. Obviously bears cannot
use a 6-inch tree for the same purpose. But those small logs still
benefit other species – maybe even bears, if they can forage grubs from
the decayed log. Longer pieces of CWD are also preferred because they
provide a wider range of diameters, in turn benefiting a wider range of
wildlife species.
Hollow logs (formed by stem decay fungi such as Indian paint fungus that
decay the tree’s heartwood while it is still standing) are particularly
useful to many wildlife species (e.g., pine marten).
Downed logs provide the widest variety of habitat if the bark is
attached, as some wildlife species or their prey will live in the space
between the wood and the bark as the latter starts to loosen. Try not to
roughen up downed logs any more than you have to if you want to keep
that habitat.
Coarse Woody Debris Arrangement. Arrangement of fallen logs is
critical to some species, particularly small mammals and their prey. For
example, martens and fishers like logs that are “jackstrawed” or loosely
piled up across the forest floor. When these log piles are covered by
snow they create a complex of snow-free spaces and runways that provide
protection and foraging.
Log orientation matters too. Logs lying parallel to slope contours
may be used more by wildlife than logs oriented up- and down-hill,
especially on steep slopes. Arranging logs this way also allows soil to
accumulate on the uphill side, which traps moisture, hastens decay, and
reduces fire risk.
Balancing competing objectives. Several researchers have
pointed out that the species that depend on CWD in forests managed for
timber are currently relying on material left in historical logging.
This often involved cutting in older forests that had more stem-decayed
wood. Current harvests in second growth stands often do not have as much
malformed wood and are made for markets that take logs down to a smaller
top diameter (e.g., down to a 4 inch top rather than an 8 inch top).
These harvests do not leave as much CWD as past timber harvest
practices.
So with all the varied habitat needs of different wildlife species,
plus all your other forest management objectives, how do you make
decisions that benefit wildlife? Unfortunately, there is not much
authoritative research that gives precise recommendations of how much
and what kinds of CWD to leave for specific species of wildlife. Barring
more prescriptive research results, the best strategy may be to leave a
variety of species, degrees of decay, and distributions of CWD to
benefit a broad range of species. How much depends on your other
objectives, but wildlife biologists rarely talk about a site having too
much CWD.
At a minimum, pay closer attention to leaving low value (cull) pieces
of stem wood out in the woods rather than burning them in one big pile,
or worse yet, hauling them to a mill that won’t pay you for them. Also
remember, the only sizes of woody debris that fire wardens measure in
assessing fire hazard are those smaller than three inches in diameter.
For more information on CWD, see Trees and Logs Important to
Wildlife in the Interior Columbia River Basin available at
http://www.fs.fed.us/pnw/pubs/gtr391 and Proceedings of the
Symposium on the Ecology and Management of Dead Wood in Western Forests
available at
http://www.fs.fed.us/psw/publications/documents/gtr-181.
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Silvicultural Decisions XI: Can
Fire Hazard Reduction Treatments
Help Achieve Other Silvicultural Objectives?
Ron Mahoney
 Pacific
Northwest forests are generally managed to meet landowner objectives,
whether held by a private individual or family, a business or trust such
as industry or tribal lands, or public land. These objectives may be
narrowly focused on specific products such as timber, but more commonly
broadly focus on natural resource management that integrates timber and
other products including wildlife and special forest products (floral
greens, mushrooms etc.) along with less measurable assets often
collectively described as aesthetics. Increasingly, social
impacts and values are included as priority objectives.
Widespread recognition of the biological and financial hazards of
decades of fire suppression and resultant high fire-risk forest
conditions has led to extensive fire hazard reduction practices.
Specifications for hazard reduction are often based solely on producing
a more fire resistant forest stand or landscape. Plans for reducing and
managing fuel hazards may meet other forest management (silvicultural)
objectives such as forest health, aesthetics, and productivity with
modifications and additions, or poorly address them.
Recently, I visited the Coeur d’ Alene Tribal Forestry Fuels
Treatment Project with Tribal Fuels Forester Eric Geisler and
several other UI professors. The Tribe had implemented treatments that
tested the fuel hazard reduction effectiveness of several machines and
different mechanical cutting tools. We now are collaborating to develop
a post fuels-treatment project that will measure the effectiveness of
alternative vegetation management methods to maintain effective fuel
hazard reduction. During our field examinations of the Tribe’s fuels
treatment project, it was very apparent that multiple silvicultural
objectives were simultaneously achieved. A silvicultural prescription
for multiple objectives, including timber production, in these stands
would have paralleled the fuel hazard reduction plan that was applied.
In this instance, the mechanical fuel treatment specifications developed
by the Tribe and Tribal natural resource managers showed that they
recognized and included many timber and social considerations in
developing treatments that met multiple resource objectives under the
primary objective of fuels reduction. While other site and forest
vegetation situations, and certainly other ownership’s constraints
especially on public lands, will make this approach of meeting multiple
objectives with fuels treatments unrealistic, this specific situation is
an excellent example of where it works and why. Hopefully, the
information presented in this article will help other landowners and
resource managers think more broadly about good silviculture on a stand
and landscape level when managing fire risks through fuels reduction.
The Coeur d’ Alene Tribe owns some 30,000 acres of trust land, and
currently intends to treat the majority of the forested land in their
fuel reduction project. Much of the 20,000 acres in these initial
priority treatments are in small blocks of forests bounded by roads,
homes and other tribal structures, cultural areas, and riparian and
other sensitive sites. Consequently, there are many potential sources
for ignition as well as many ecological, financial, social and cultural
properties and resources to protect. Although some of the treated areas
serve essentially as fire-resistant buffers for these other values,
entire forest stands will be treated, following current trials to show
which mechanical treatment is the most effective and efficient.
Following initial fuel reduction treatments a new Tribal project in
partnership with the University of Idaho will conduct experiments to
test alternative strategies to maintain desired fuel levels.
Post-treatment management would seem to be an obvious requirement, but
many land owners and managers have made fuels reduction treatments with
no provision for continued maintenance. The amount and species
composition of re-growth and in-growth of vegetation, including invasive
species, is a critical aspect of sustaining targeted fuel levels.
It is no accident that the Coeur d’ Alene Tribal forest was much
closer initially to the "prescriptive ideal" for the sites we visited
than many other forests on similar habitats. The Tribal forest has
sustained fire suppression for a much shorter time (about 40 years vs
80-100 years for much of the regional forest landscape). Historically,
both Tribal Trust lands and individual forest land allotments were
regularly under-burned by tribal owners and managers until the later
1960’s. At the same time, Tribal cultural values and ecological
understanding led to favoring large, healthy trees. In this landscape,
that meant the seral species including ponderosa pine, Douglas-fir,
western larch, and western white pine, species that continue to be
favored to retain in fuels treatments and other Tribal management
specifications. Consequently, a well-stocked overstory of seral species
was present on all of the forest sites we visited. The understory is
composed of diverse, largely native species that will be retained or
removed to sustain wildlife and cultural values while reducing fire
hazards.
A closer look at some of the stand conditions and fuels treatments,
and their silvicultural implications, illustrates how compatible these
management goals are, and reveals factors other land owners and managers
might consider in fire hazard reduction prescriptions:
- The habitat types in this situation are primarily
in the grand fir series ranging from its drier to wetter phases. The
climax species, grand fir, is near the margin of its ecological limits
for growth and will be the first species to experience stress and
associated forest health problems. Some of the hazard reduction sites
are at the wetter end of the Douglas-fir series or at the drier end of
the western redcedar series but in general, the species designated to
leave under fire hazard reduction, ponderosa and white pine, western
larch, and Douglas-fir, are the same tree species I would prefer under
a silvicultural prescription where the objective is forest health,
sustainable timber production, stable, diverse habitats and
consideration of appearance, accessibility, and resistance to fire.
- The tree species designated to remove in the fuel
treatments are all grand fir, and commercial-sized lodgepole pine,
along with any other species of poorer form, smaller, or less healthy
than the nearest designated leave tree within 15 feet. This provides
some commercial harvest during the treatments, and future harvest
while suppressing establishment and growth of undesirable understory
vegetation and conifer regeneration. This designation is compatible
with most silvicultural goals, but the spacing of leave trees, 15
feet, would be more variable and likely wider depending on tree size,
if timber productivity was a primary objective.
- The pre-treatment understory in these forests is a
diverse composition of native species typical of the grand fir habitat
types and is dominated by tall and medium height shrubs, with forbs
and grasses and few invasive weed species. The understory also has
significant conifer regeneration that is highly variable in
distribution and species. The preferred shrub species to leave include
large scattered clumps of Rocky Mountain Maple as the highest priority
species, along with service berry and chokecherry, bittercherry and
other fruiting species for wildlife habitat. In addition, riparian
areas are designated as preferred habitats to leave clumps of these
taller species, along with shrub willows, aspen and lower, moist-site
vegetation. Snowberry is left where it is shorter (<15"), but is
designated for removal where it is taller and/or forms large blocks of
continuous cover.
- Tall, dense clumps of shrubs are left primarily
for wildlife habitat, particularly in riparian areas. Riparian
vegetation, whether along streams or on seeps and other wetter,
micro-habitats, will also stay more green and have higher moisture
content through the typically dry summers. Retaining this vegetation
in scattered, more green and moist clumps, will add little to the fire
risk on these sites and add greatly to wildlife habitat and visuals.
Retaining tall, dense clumps of maple also increases site stability.
Rocky Mountain maple typically grows on spots with sub-surface
irrigation from cresting water tables. It is also found on seeps that
may form vernal pools in the spring (important habitat for many
amphibians).Maple clumps stabilize wet-soil microsites that would be
subject to compaction or slumping if removed with mechanical equipment
or located in or just above roadbeds. These are important factors to
consider in silvicultural prescriptions for any objective.
- Removing undesirable tree species and excess,
defective trees in the overstory certainly accomplishes fire reduction
and timber goals. Treating clumps of young conifer regeneration and
scattered, suppressed trees is equally important. Tribal
specifications designate pines, larch and Douglas-fir as preferred
seedling/sapling leave trees, and require a spacing of about 15-18
feet, and a little closer in a few evenly-spaced plantations. This
treatment also meets the objectives of managing the composition of the
current forest and its options for future regeneration, and of
maintaining a healthy, productive and diverse forest.
- Removing shrub species with lower wildlife value
and higher fire-risk characteristics, especially ninebark, oceanspray,
and taller snowberry, also removes a major component of competition
for more desirable, less hazardous understory vegetation and tree
seedlings. It also removes the lower level of "ladder" fuels which can
lead to devastating crown fires, should ignition occur. Ladder fuel
reduction is further achieved through the spacing of overstory and
understory conifers, especially by removing grand fir and lodgepole
pine, which retain long crowns either as green foliage (grand fir) or
through poor self-pruning (both species).
- The treatment specifications also require
vegetation designated for removal to be cut at low levels to
discourage rapid sprouting or retention of any green growth, and to
break both live and dead material into pieces that will put most
debris in contact with the ground to encourage decomposition, sustain
nutrient cycling, and reduce fuels’ continuity and burn rates. A
silvicultural prescription should consider the quality of understory
and overstory for wildlife habitat as well as timber and other
productivity, the need to reduce competition for desired tree, shrub,
and lower vegetation, and the reproduction of desired tree species.
Silvicultural objectives also may include recreation access and forage
production for livestock and wildlife. These fuel treatment
specifications achieve these goals, and more importantly, make them
economically feasible. In many silvicultural prescriptions, the
objective of treating understory vegetation including excess or
undesirable conifer reproduction, is often specified but not achieved
because of the significant cost of these treatments relative to the
value of commodity production alone. This leads to the final point I
would like to make about merging fuel reduction objectives with other
silvicultural objectives: the economic and other benefits of fuel
reduction treatments on many forest stands will justify the cost of
high-priority silvicultural treatments for many additional management
objectives that are often not achieved when the timber cost/benefit
ratio alone is considered. In many cases, reducing understory
competition, managing vegetation composition including conifers and
desirable native species of shrubs etc., and discouraging or
eliminating invasive species, are recognized as priority objectives
from an ecological and long-term productivity and sustainability
perspective, but are not accomplished due to financial constraints.
The huge financial and ecological costs of ignoring unhealthy, high
fire-risk forest conditions, especially where they could impact
structures and threaten human lives, has led to a new era where
investments in fire hazard reduction treatments are being made. In some
current forests, conditions are such that fuel treatments will do little
to address other silvicultural objectives. But many forests designated
for fuel reduction present an opportunity to economically address many
other silvicultural objectives addressing recreational, ecological, and
sustainable timber management goals. At a minimum, fire hazard reduction
plans should not only address immediate catastrophic fire risk, but also
consider setting the initial conditions that will help resource managers
move towards more comprehensive plans and specifications to achieve a
broader array of integrated objectives.
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Silvopasture – Growing Trees in Your Pasture, or Vice-Versa
Randy Brooks
 Forestry and livestock production are mainstays of the
natural resource based economies of North Central Idaho. There is also a
strong tradition of livestock grazing in other forests across the West.
Silvopasture, the combination of forest management and improved forage
species, is a more intensive, controlled application of this traditional
use of livestock grazing and growing trees. Silvopasture is the
deliberate introduction of timber into a forage production system, or
vice-versa. With silvopasture, timber and pasture are managed as a
single integrated system. It is not utilized as much in the West as it
is in the Southeast, but is most often implemented to increase
profitability, reduce risk, and augment environmental benefits from land
management. Silvopasture systems are designed to produce high-value
timber while providing short term cash flow from livestock.
The ability of recently forested land to grow trees can
be predicted by the performance of the previous stand. However, the
ability of pasture or rangeland to support commercial timber production
is harder to predict. Many forage plants are more shallowly rooted than
trees are, and a productive forage pasture may have soils that are too
shallow to support commercial tree production. Since soils can change
significantly over a short distance, the presence of trees near a
proposed silvopasture is no guarantee of successful tree establishment
and growth. Local University of Idaho Extension and Natural Resource
Conservation Service offices are good sources of information about soil
suitability for specific pasture and tree species.
Most folks would prefer planting trees into an existing
or recently seeded pasture due to ease of operation. However, vegetation
control is critical, especially when planting trees into an established
pasture where grass roots form a fibrous mat throughout the upper soil
layer. This can allow grasses to out-compete tree seedlings for
moisture. In dry summer climates, conifer seedlings grow best when
competing vegetation is removed for the first three years. This can be
accomplished through various means of site preparation. Apply an
herbicide or plow a two to four foot wide strip for each row of trees to
be planted. In some areas, a prescribed burn or pesticide application
may be needed to control rodents prior to and after tree planting.
Follow-up with a selective herbicide may be needed for the next two to
three years until trees are well established.
The desired pasture mix will vary with site
characteristics and the desires of the land manager. Orchardgrass, tall
fescue, and perennial ryegrass along with a clover species are commonly
used silvopasture forages. Nitrogen fixing clovers are often seeded to
provide high quality feed for livestock and to serve as a biological
source of nitrogen for trees and associated grasses. Legumes often have
more exacting nutrient requirements than do grasses, making a soil test
and possible subsequent fertilization an important part of the
management plan. The forage composition will change over time as trees
grow and modify the environment. Trees generally have little impact on
forage production until shading becomes dense enough to limit sunlight
to the understory. Forage production of warm season species can be
reduced somewhat. Orchardgrass seems to tolerate the environment under
trees better than perennial ryegrass or Kentucky bluegrass. Although
tall fescue does well under trees, it has the lowest forage value and
highest degree of competition of the forages.
Douglas-fir and ponderosa pine are the two predominant
timber species that grow best in our area. Larch, as well as western
white pine can also be grown, but western white pine is subject to white
pine blister rust. Regardless of what species is used, it is generally
recommended that seedlings are purchased locally or from a locally
adapted seed source. Such seedlings are both quicker to establish, grow
faster, and can be more tolerant of browse and other damage.
Silvopastures are generally planted at about 200-300
trees per acre, and can be planted in grids or in single rows, multiple
rows, or even clusters. This planting style provides for wide open
alleys for forage production and easy access for livestock grazing, hay
harvesting, fertilizer spreading, spraying, and other agricultural
practices. Alley width should be determined by width of farm equipment.
For example, a 20 foot alley provides easy access for cutting hay with a
16 foot swather. This same spacing allows for mechanized harvesting
later when trees mature. There is plenty of room for creativity when it
comes to planting trees in combinations, however, rows of three or more
are generally not recommended as the inner rows of trees may be
out-competed by the outer rows.
Trees may be damaged by livestock or wild animals which
can eat, rub, or step on them. Multiple damage events may kill trees,
but single events generally only slow growth. Conifers are especially
sensitive to the removal of the topmost leader (terminal bud). This is
the most palatable, nutrient packed portion of the seedling. Leader loss
results in dramatic loss of height and diameter growth and stimulates
production of multiple leaders or forked tops. Most tree damage is
likely to occur in the first two to three years when they are small and
do not have their resinous chemical defense well established. The best
way to reduce the risk of damage during this period is by haying rather
than grazing. This approach does not resolve the problem of damage by
native wildlife herbivores like deer and elk. Young trees may be
protected with chemical repellants, mesh tubes, or some type of
appropriate fencing. Sheep, goats, and deer are more likely to eat
needles than are cattle or elk. Established conifers are not as
attractive to large herbivores when other forage is present. If heavy
browsing is observed there may be a deficiency in the livestock diet.
Trees that provide shade or wind protection can have a
climate stabilizing effect by reducing heat stress and wind chill of the
livestock. Protection from trees can reduce the direct cold effect by
50% or more and reduce wind velocity by as much as 70%. Livestock
require less feed energy, so their performance is improved and mortality
is reduced. In contrast to concentrated livestock operations,
silvopastoral systems are less likely to raise environmental concerns
related to water quality, odors, dust, noise, disease problems, and
animal treatment.
For more information on silvopasture, contact your local
University of Idaho Extension Office or Natural Resources Conservation
Services Offices.
For more information on silvopastures, visit the
following websites:
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http://www.unl.edu/nac/silvopasture.html
•
http://smallfarm.ifas.ufl.edu/Forestry/Silvopasture.htm
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