|VEGETATION IN THE GRAVELLY LANDSCAPE||Joe Casey, BLM|
|Al Kyles, FS|
|Kevin Suzuki, FS|
|Bob Brannon, MtFWP|
B. Forest Stand Structure
C. Uniques Species and Threatened, Endangered and Sensitive Plant Species
D. Noxious Weeds
E. How Natural And Human Disturbance Has Affected Vegetation
F. Ecological Concerns for the Gravelly Landscape
G. Relationship to Ecological Concerns at a Larger Scale
B. Forested Habitat Type Groups
APPENDIX C - Detailed description of habitat type groups
APPENDIX E - Resolving resource conflicts - a description of risks and tradeoffs
APPENDIX G - Opportunity for vegetation treatments, by ownership, ELU, veg class
A . Cover Types
Cover types represent dominant species or life forms occupying the landscape today. Cover types in the Gravelly Landscape were described using information from several sources. First, to determine basic vegetative cover landscape wide, vegetation was classified using satellite imagery and mapping called "GAP analysis". GAP analysis was done by Rolle Redmond at the University of Montana prior to 1996. This level of information was most useful on lands for which we have limited or nonexistent vegetation data collected. Prior to this analysis, land managers have not had a complete look at vegetation distribution and condition across all ownerships. This has left a void in assessing the cumulative impacts of management actions.
The GAP analysis was based on satellite images of northern Idaho and western Montana taken in the early 1990's. One of these satellite images contained all of the Gravelly Landscape. It had over 50 groups of image classifications (spectral classifications) of which 29 were applicable to vegetation in the Gravelly Landscape. These 29 groups were further pared down to 10 groups to simplify the vegetation classification and data associated with this process. The GAP analysis of the satellite imagery was improved in 1997 with a second interpretation of aspen and range types, completed through the Remote Sensing Applications Center in Salt Lake City, Utah. This second interpretation improved the accuracy of aspen, sage and grassland mapping using additional ground truthing in the southwest portion of the Landscape. The final 13 groups mapped for the entire Gravelly Landscape area are listed in Table 1 and displayed on Map #12 in the map appendix.
A second source of much more specific information came from Bureau of Land Management (BLM) and Forest Service electronic data bases. While not displayed here, maps are available for specific forest cover types and stand structures on both BLM and FS land. In addition, the Timber Stand Management Reporting System provides detailed data on for all Forest Service lands.
A brief summary of the vegetation shows the dominant cover type is grass/sage which occurs on almost 75% of the Landscape. The next largest vegetation group is conifer forests which make up about 20% of the area. The third largest cover type is agricultural land at about 4%. The remaining area is riparian, rock, wet meadows, water, urban or developed areas. This information is expanded in Tables 1 and 2 and Figures 1 and 2.
|Vegetative Map Legend||Description|
|Agricultural||Hay meadows, alfalfa fields, grain fields, etc.|
|Grass/Shrub||Foothills grasslands, Disturbed grasslands, Montane parks.|
|Dry Grass||Upland grasses-herb communities below 6800 ft elevation|
|Moist grass||Upland grass-herb communities from 6800 to 9200 ft elevation|
|Alpine grass||Upland grass-herb communities above 9200 ft elevation|
|Mesic Upland Shrub||Wet upland sites dominated by shrubs.|
conifer tree canopy that begins at the grass/sage/conifer edge and extends
Mostly Douglas-fir with some lodgepole pine or Rocky Mountain juniper.
|Lodgepole pine||Mid slope conifer tree canopy that is mostly lodgepole pine with some limber or whitebark pine and extends upslope to about 7800' elevation.|
|Subalpine fir complex||Generally the upper reaches of the coniferous forest above 7800' with either subalpine fir or subalpine fir mixed with other conifer.|
|Water||Large enough bodies of water to show at the landscape scale.|
|Rock||Rock, barren alpine tundra, other mixed barren land.|
|Urban and some subdivisions||Towns, some subdivisions, etc.|
|Riparian*||Stream bottoms, river corridors, and associated vegetation such aspen patches, willows, spruce, etc.|
Satellite imagery has its limitations. When information is grouped to improve accuracy, the maps tend to reflect the dominant vegetative types. Specific smaller parcels can be lost and potential for errors in classification of small tracts increases. This ecosystem analysis is the broad view from a distance and has some limitations.
Finally, unique vegetation types such as sensitive, rare or endangered plant communities cannot be easily denoted on mapping at the landscape level. However, where this information is available, it is incorporated. Any potential project level work affecting these resources would be analyzed through the NEPA process using more specific available data.
The ownership jurisdiction
and approximate acreage in the Gravelly Landscape is shown in Table 2.
|Jurisdiction||% of Landscape||Total
|Agricultural||Grass/ Shrub||Mesic||Douglas-fir||Lodgepole||Sub- alpine||Water||Riparian||Rock||Urban|
|Bureau of Land Management||21.43||420,000||0||306,000||1,000||37,000||30,000||40,000||100||1,700||4,200||0|
|Bureau of Reclamation||0.05||1,000||0||1,000||0||0||0||0||0||0||0||0|
|Mt Fish Wildlife & Parks||0.92||18,000||0||17,200||0||200||200||0||0||400||0||0|
|Mt Dept. of Natural Resource Conservation||12.55||246,000||900||225,000||50||9,150||6,000||3,500||0||800||600||0|
B. Forest Stand Structure
Forest species and stands structures were described using satellite imagery and improved on FS lands using TSMRS data, See Map #13. Table 3 and Table 4 display their distribution across the Gravelly Landscape.
|Aspen and Conifer mix||
|Infant||= seedling to sapling size trees, from 1 to 20 years of age|
|Juvenile||= pole size or uniform stands, undifferentiated, from 20 to 80 years old|
|Gold||= older mature stands, generally have more than one layer of foliage in the canopy, dominant trees older than 80 years|
Aspen and conifer mix were not discussed separately on the basis of stand structure because of the difficulty of mapping these very small stands.
Distribution of these structural
classes by species across the landscape are described in Table 5 below.
|Species||Infant or colonization||Juvenile||Gold||TOTAL|
|Douglas-fir||548 acres (0.5%)||32,521 (29%)||78,493 (70%)||111,562|
|Lodgepole and subalpine fir||4,032 (1.5%)||58,851 (22.5%)||200,662 (76%)||263,545|
|Aspen/Conifer||110 (1%)||2969 (26%)||8430 (73%)||11,509|
1. The decline of aspen from the landscape is readily apparent from its present condition. This early seral species is dying off because it cannot maintain a competitive edge without disturbance in the forest canopy. As it dies off, it is being replaced by more shade tolerant conifers instead of young aspen seedlings. While the species has probably never been a dominant feature in the landscape, a study in the southwest portion of the Gravelly Mountains shows a 47% decline in aspen coverage between 1945 and 1963.
2. The existing Gold portion
of the Douglas-fir Group has a large cohort of understory trees less than
100 years old. Historically, the low elevation dry Douglas-fir stands took
on the character of open savannah-like stands with an abundance of forage
underneath. Low intensity ground fires cleaned out these stands periodically,
fire-proofing the large old trees remaining. This change in conditions
represents three significant threats to the continued existence of these
4. There is an increase in the areas converting from open grass and sagebrush to the Infant class of Douglas-fir. This is evident in photo comparisons from 1945. The forested stands that come in on these sites are typically unhealthy as they get older. The trees are at the outside of their range and develop problems with competition for nutrients and moisture, leaving them susceptible to pathogens. The conversion of sagebrush habitat to Douglas-fir habitat may represent either a plus or minus to other resources, like wildlife habitat, depending upon the location, amount and duration of this conversion. It does represent some long term fire control problems along urban interface.
For more information about stand structure as it relates to potential vegetation and trends , see Section E, F, and G below as well as Section "II. VEGETATION POTENTIAL".
C. Unique Species and Threatened, Endangered and Sensitive Plant Species
Southwest Montana is a unique and floristically rich corner of the state. The richness of the flora in combination with the climate, geology, topography and elevation range give us a full range of diverse plant communities in the Gravelly Landscape. Plant communities range from the dry valley grasslands to dense conifer forest on the mountain slopes and on to the high alpine tundra on the mountain peaks. Riparian areas offer another whole range of diverse plant communities. The vegetation classification currently being used for this landscape is very generalized and does not reflect the diversity of the area.
Wherever you may go within southwest Montana, whether you are on the valley floor or at the top of one of the mountain peaks, you will come across interesting and unique plant communities. Some areas are managed specifically for these unique array of plant communities. Red Rock Lakes National Wildlife Refuge, managed by the U.S. Fish and Wildlife Service, is a mix of lakes, ponds, marshes and other wetland communities managed for trumpeter swans. The Beaverhead-Deerlodge National Forest maintains three Research Natural Areas (RNA): Cave Mountain, Cottonwood Creek and Cliff Lake. Research Natural Areas are part of a national network of ecological areas designated for research and education and/or to maintain biological diversity on National Forest system lands. A similar network of ecological areas is the BLM Area of Critical Environmental Concern (ACEC). The Dillon Resource Area is looking at designating the Centennial sand dunes under the ACEC network. These sand hills support a variety of uncommon plant communities and provide habitat for four plant species of concern. They are also the highest elevation sand dune habitats in the Northern Rocky Mountains.
Many plant species can only be found growing in this area of the state. In Montana, there are no plant species listed as endangered and only two that are listed as threatened. Of the two threatened species, Ute ladies' tresses, a member of the orchid family, was first discovered in the state in 1994. This species has the potential to be found in the Gravelly Landscape. In Beaverhead and Madison Counties, just over 100 plant taxa are tracked by the Montana Natural Heritage Program as species of concern. Plants are listed as species of special concern based on the plants rarity, threat to survival or due to limited knowledge of the species. The Forest Service and BLM further refine this list to focus on those species known to occur or suspected to occur on public land. Currently, the Beaverhead-Deerlodge National Forest maintains a list of 38 species as sensitive. The BLM Dillon Resource Area lists ten species as sensitive.
D. Noxious Weeds
Noxious weeds are the greatest threat to the overall vegetative diversity and soil productivity in the Gravelly Landscape. A variety of noxious weeds have already established a foothold in the area, spotted knapweed being at the top of the list. Other weed species are found just outside the landscape boundary and have the potential to invade. Disturbed ground provides the best seed bed for weeds to establish by eliminating competition from other native vegetation. Most weed species have evolved to take advantage of this type of situation by being able to germinate and grow in harsh environments. The ground disturbance associated with construction of subdivision roads, house construction, logging and agriculture crops create prime sites for weed invasion. The primary vector for introduction of most noxious weed seed is transport to the area by vehicles, be it car, truck, motorcycle or ATV. Sites occupied by noxious weeds are currently being mapped electronically on FS lands.
E. How Natural And Human Disturbance Has Affected Vegetation
Specialists analyzing vegetation need to understand what kinds of changes occur over time, to know how we got where we are today and what the potential for future vegetation is. The different components of the Gravelly Landscape are by no means static. Sometimes change occurs quickly, such as from floods, fires or landslides. Other times, the changes are slower and more subtle, as from climate changes. Certain types of landscapes are prone to natural disturbances. Portions of the Gravelly Mountains are particularly active geologically; collapsing, shifting and sliding.
A disturbance is an event that changes the trend of ecosystem development; in this case, vegetative development or succession. Disturbances play many roles in ecosystem functioning. One example is flooding. Floods play many roles, including flushing debris and accumulated fine sediment or delivering material for soil development to the flood plains. Natural disturbances that affected vegetation composition, structure and function in the Gravelly Landscape included plant succession, insects, disease and fire.
Humans also have had profound effects on the Gravelly Landscape. Agriculture, timber harvest, mining, livestock grazing, hunting and the exclusion of fire have resulted in changes in succession, disturbance regimes and associated vegetation. Specific activities include construction of roads, introduction of exotic plants or animals, conversion of land to agriculture or other uses. When natural disturbance events are detrimental to humans, we attempt to control them or minimize their effects -- often disrupting the normal functions of the disturbance. In many cases, human activities interact with natural disturbances to produce an entirely new effect. This has been the case with both fire and floods.
There has been considerable discussion and some disagreement between resource specialists on the Gravelly vegetation and wildlife subgroup on the role of disturbance processes in determining the types, condition and potential for change in plant communities in the Gravelly Landscape. The team agrees that human activities have affected vegetation in numerous ways. The team agreed that the effect of both human and natural disturbances on plant communities can be documented since 1940. Each member of the team could not agree, however, on the role and influence of fire, in particular, as a natural disturbance prior to 1940. The disagreement centered on whether evidence of historical fires at specific locations can be used to describe a pattern of fire frequency and intensity across the entire landscape. A primary concern was current fire research specific to southwest Montana (Gruell, Barrett, #need citations) may lead to management for more early seral stages in grass/shrubland or low elevation Douglas-fir. This was viewed as detrimental to other resource uses, such as wildlife.
In order to deal with the two viewpoints and still try to understand what the trends in vegetation development might be, the team developed two scenarios for describing how we got where we are today and what the potential for the future is. These are further described in the following section "II. Vegetation Potential in the Gravelly Landscape" and in Appendix C. The role natural and human disturbances played in our current vegetation patterns is described below in very broad terms. Also refer to page #6 for a detailed description of the magnitude of specific human disturbance factors (logging, mining) within each Ecological Landscape Unit.
Below is a description of
the broad vegetation cover types and how they have been affected.
These portions of the Gravelly Landscape are generally in the vicinity of the major stream or river corridors. They comprise a little over 4% of the area and generally are the highest monetary valued lands in the area. A great deal of change has occurred in the valley bottoms. These acres would have been classed as grassland and sagebrush/grass communities prior to settlement of the area. The establishment and growth of towns and transportation systems, ground breaking for agricultural crops, livestock grazing and, more recently, subdivision development have decreased the number of acres of native vegetation. These activities required intensive water development for domestic use or irrigation. Virtually all of this land is in private ownership. It should be noted that many of the subdivisions are not identified on the vegetation map due to the limitations of scale and sparsity of structures. Most of the acres associated with these subdivisions are not captured in Table #2.
This is the vegetation that extends upland from the riparian zone to lower foothills of the mountains. It consists of a mix of grasslands in the lowest portions to grass/sage and Douglas-fir in the upper extent of its range. Some of the typical species found in this type are grasses such as Idaho fescue and blue bunch wheatgrass, shrubs such as sagebrush or mountain mahogany and conifer trees such as Rocky Mountain juniper, limber pine and Douglas-fir. It is the largest vegetative type in the Gravelly Landscape, comprising over 73% of the area. Almost 45% of this vegetative type is in private ownership. The general trend of vegetative succession is from grass to sagebrush on the more developed soils. The pattern of sagebrush is a result of several factors such as fire frequency, grazing intensity and climatic patterns. Fire had an influence on vegetation before settlement of the area by European descendant peoples. However, precise documentation of fire's role is difficult to obtain because of the lack of historic evidence in the grass/shrub vegetation type by itself. Fire has occurred as a result of both natural and human caused sources. There is documented evidence of the occurrence and frequency of fire in some portions of the grass/shrub and Douglas-fir interface. On these sites, the lower reaches of this interface area have had fire intervals of 5 to 20 years. In other areas, there is no evidence of fire frequency. Segments of this vegetation type extend into the mid elevation range of Douglas-fir. This is a function of aspect with some grass/shrub communities on some south to west facing slopes in more heavily timbered areas. These areas are not delineated on the landscape scale map or any associated tables or graphs.
Grazing intensity on this vegetation type has historically been moderate to intense in the past 100 to 130 years. This activity was initially associated with supporting the early mining communities and other communities that resulted from this activity. Generally, the amount of domestic livestock grazing from the 1860's through the post World War II years was higher than current stocking levels. With the utilization of finer fuels (grasses and some shrubs), there has been a corresponding decrease in natural fire's ability to become as large as it may have been in presettlement periods. Additionally, fires were generally suppressed by the local population while they were still small.
Climatic patterns appear to be cyclic. Generally, the grass/shrub vegetation community receives less precipitation than the higher elevation vegetation communities.
Generally, timber harvest in the low elevation Douglas-fir has been very limited due to the poor quality of merchantable timber that occurs even at the upper reaches of this type. Another "disturbance" that is becoming more common in this type is individual housing or subdivisions. The potential for this is increasing as the value of the land for housing development continues to outstrip its value for domestic livestock grazing.
This is a very limited vegetative type primarily associated with riparian areas. Typical plants are silver buffaloberry and greasewood. This type covers less than 1% of the Gravelly Landscape. The majority of this is on private lands in the river bottom between Twin Bridges and Dillon.
This vegetation type interfaces with the grass/shrub community at its highest elevation levels and is the beginning of the relatively continuous conifer cover as elevation increases. It covers a little over 6% of the area and about one third of all the conifer cover types in the Gravelly Landscape. Almost 80% of this type is in public ownership. It is important to remember that there are some components of the grass/shrub community mixed in with the lower portions of this type and some of the lodgepole pine component intermingled with the upper elevation of this type. Characteristic stand structures of this type are open grown larger diameter Douglas-fir with a grass/shrub understory. These stands may also have some smaller Douglas-fir trees interspersed among older growth trees. With increased elevation and precipitation, the density of stands will generally increase along with the amount of fuel loading. This is a function of the increasing productivity of this type with elevation. Without some type of disturbance these stands will usually have multiple-storied canopies, which increases the potential for crown fires.
While some domestic grazing is common in this type, it is generally less productive than lower elevation types. Historically, fire has played a significant role in this type. Documented fire frequency shows that fire intervals vary from 35-40 years or longer. Historic fires have generated individual stands which average from 40-200 acres with rare exceptions over 500 acres in size. Insects and disease levels have been moderate, with scattered Douglas-fir bark beetle and spruce budworm attacks most recently occurring in the 1980's. Historic logging occurred where there was an opportunity for products such as mine timbers, fuel wood, post and poles and barn or house logs. Some timber has been harvested on both private and public lands in this type from the 1970's to the present, but the majority of this activity has been in the higher elevation portion of this vegetation type.
One other component generally found near or within the Douglas-fir vegetative type is aspen. Many of these stands are mixed in with conifers. The vigor of these stands is declining over the landscape for a number of reasons, one is ecological succession. Generally, aspen will not reproduce under existing older stands, which leaves these stands susceptible to succession by either more shade tolerant species such as Douglas-fir or trees such as lodgepole pine which find a small niche in the understory and are able to out compete the aspen. This situation does not necessarily apply to aspen stands found in riparian or grass/shrub types.
The next higher vegetation type generally in the vicinity of the mid slope is lodgepole pine. It composes almost 8% of the Gravelly Landscape, with about 90% of this in public ownership. Often this species is intermixed with Douglas-fir in the lower elevations and subalpine fir, Engelmann spruce or whitebark pine in the upper portion of its range. Increases in precipitation results in increased productivity for these types and generally these stands are the most productive in the Gravelly Landscape. Stands of pure lodgepole may have one or more light ground fires in 20 to 60 year intervals, however, this species has limitations as to the number of these ground fires it can tolerate. Under certain wind conditions a fire can reach the canopy and become a patch or stand replacing event. Where other light tolerant species such as Douglas-fir, subalpine fir or Engelmann spruce have become established in the understory, the potential for fire severity and stand replacement increases. Such events likely occurred at 150-200 year intervals. In general, fires tend to become less frequent but more severe in this vegetative type.
Domestic livestock productivity is more limited in this type than at lower elevations. Timber harvest and road construction in this type on private and public lands has been the most intensive human caused disturbance due to the high productivity of these sites. Regeneration is usually successful and forms some areas of seedling/sapling stands in the landscape. Again, this influence is difficult to display on a landscape scale map. Insect activity, primarily bark beetle, has been moderate, with western balsam bark beetle mortality increasing at the higher elevations.
Subalpine fir complex
This complex generally forms the upper reaches of forested areas and comprises a little over 6% of the landscape. All but 3% of this vegetation type is in public ownership. The major conifer species generally found in the lower portion of this vegetative type are lodgepole pine, subalpine fir and Engelmann spruce. As elevation increases, the lodgepole pine decreases and the mix is generally subalpine fir, Engelmann spruce and whitebark pine. Another significant "marker" is the lack of Douglas-fir in this type. Fuels also tend to decrease with elevation. Correspondingly, the historic effect of fire also decreases with elevation. In the lower portions, stands are usually either too wet to burn or if they are dry enough they are susceptible to wind driven crown fire which may be a patch or stand replacing event. Thus, the fire intervals in the lower reaches resemble those in the lodgepole pine vegetative type of 150-200 years. Human influence has been in the form of logging in the more accessible areas with generally favorable regeneration results. As with the lodgepole pine type, this activity is difficult to display at the landscape level.
At its upper most reaches, this type gives way to grass/rock and a limited amount of conifers, usually including whitebark pine, in small niches where they are capable of surviving. Generally, this occurs at about 9200' above sea level. This upper area is characterized by extremes in temperature, precipitation and solar radiation. Trees become shorter and stunted in appearance. Fuels become much more patchy and light. As a result, fire is a secondary influence on tree development. This is a function of the cold, moist, rocky, snowbound, unproductive environment.
Water and Riparian
Water identified by satellite imagery is generally the larger bodies of water, 5 acres or larger. The location and arrangement of numerous small ponds, lakes, smaller streams and wetlands are not indicated on the map, but are very influential in the distribution and use by wildlife dependent upon these habitat features. Vegetation typically included in both of these types includes sedges, willows, cottonwood, aspen, etc. The combination of these types covers about 1.5% of the landscape. Disturbance factors common to some of these areas are grazing by domestic livestock, historic diversion for mining, reservoirs, irrigation ditches or canals, etc. Also, natural disturbances such as periods of drought or above average precipitation, beaver activity and flood events occur in these types. In some cases, these disturbances have altered the associated vegetation and function of these features in a permanent fashion. Disturbance effects in riparian areas were described in the packet of information on "Geology, Soils and Water in the Gravelly's".
Rock occurs at all elevations in the Gravelly Landscape, from outcrops in valley bottoms to high mountain rock formations and talus slopes. It could also include areas barren enough of overlying vegetation that satellite imagery would interpret this as rock. In some areas, mineral or ore-bearing veins in rock have been mined, which would constitute the major human cause of disturbance. This type composes almost 1% of the landscape.
Agency specialists in vegetation ecology and wildlife biology compared the existing condition of vegetation to historical trends and vegetation potential. The team identified six areas of concern they agreed on and one area they did not.
Agency Resource Specialists agree that:
1) Aspen is declining in health and distribution. Aspen is naturally a small but important component of the landscape. Documented decreases in aspen acres have occurred since the 1940's. Most stands are mature to overmature. The aspen component is becoming smaller due to climate changes, plant succession, grazing by cattle and wildlife, and lack of fire or other disturbance. Loss of aspen would reduce plant species diversity and also represent a loss of key wildlife habitat.
2) There are more high elevation subalpine fir stands and older stands than ever before. Subalpine fir occupies more sites than it has in the last 50+ years. Lodgepole and whitebark pine stands in many areas are slowly converting to subalpine fir due to insect (mountain pine beetle) or disease (whitepine blister rust) mortality and succession. The trade-offs are as potential for old growth habitat increases, there is less whitebark or lodgepole pine habitat for species reliant on those habitats, and heavier fuel loading occurs (higher risk of high intensity fires).
3) There is an increase in older mid-elevation lodgepole pine and Douglas-fir stands . Lodgepole pine relies on fire to regenerate young stands. In the absence of fire, existing stands continue to age. Very few young stands of either lodgepole or Douglas-fir occur at mid-elevations. The stand structure of Douglas-fir has also changed from more open grown older trees, to multistoried thicker stands. The benefits are as old growth lodgepole pine habitat increases and Douglas-fir stands become thicker, there is more habitat for forest habitat species and more wildlife security cover. The concerns are heavier fuel loading, risk of high intensity fires, and loss of timber products to insect and disease and natural attrition.
4) There is an increase in Douglas-fir cover along the grass/sage interface with Douglas-fir. In the absence of disturbances, grass/sage stands on favorable elevation and aspects become occupied by young Douglas-fir trees. This is a natural part of succession to climax, but it is occurring on sites marginal for supporting healthy forest stands. The benefits are some increase in habitat for forest habitat dependent species and additional security cover for big game species. The trade-offs are increasing the fuel loading which means harder to control fires in areas where subdivisions are increasing and loss of sagebrush habitat for sage dependent species, and unhealthy forest stands susceptible to disease.
5) Riparian vegetation is changing in character. There has been a reduction in composition and distribution of native vegetation with an increase in nonnative vegetation. The concern is this contributes to a loss of stream function and a reduction in wildlife habitat diversity. The benefits are related to human use of the sites, whether they provide forage for domestic livestock, road corridors, or recreation sites.
6) Grass and sagebrush cover types are changing. Agricultural practices have reduced native grass and sagebrush cover types, converting them to nonnatives through cultivation and planting. The potential for natural processes continuing on these sites is reduced. The benefit is production of food for humans and livestock. The trade-off is a loss of the amount of grass/sagebrush habitat available for wildlife species or a change in the character of the vegetation available. There is also some redistribution of where that habitat occurs.
Agency Resource Specialists do not agree on:
The balance of grass and sagebrush as it is distributed across the landscape. Sagebrush/grassland is a prevalent community across the Gravelly Landscape, more so here than many other landscapes in southwest Montana. The question is whether or not the prevalence of this community type is any different now than it was in the past. Certainly there would be differences when we think of geologic time. There may also be differences, at least in vegetative composition, since European settlement of the west. Though there is even question about this. But, is there a difference in the prevalence of this community type in recent recorded history (the last 350 years)? Undoubtedly, on a small scale there have been short term changes resulting from natural influences such as fire, insects, disease, precipitation, etc. But have these influences been significant on the landscape in magnitude or frequency? There have been changes on some scale and for the short term because of human influences: sagebrush treatment (prescribed fire, spraying, plowing, etc.), grazing, fire suppression, etc. But which of these, if any, have had a major influence on the distribution of this community type?
The sagebrush/grassland community is the one where much of the management controversy exists. However, the questions asked above could apply as well to the other community types discussed. It is important to consider the value of these communities in their current status, ecologically, and from a wildlife habitat perspective, in addition to considering whether or not there is a significant change in their relative presence.
The value of these vegetation communities and recommendations for how they should be managed in the future, recognizing the multiple values to wildlife, recreation, scenic values, and economic uses is continued in Chapter 3. Recommendations for the Future. At that point, trade-offs between the various resource values and uses are discussed, weighed and balanced.
G. Relationship to Ecological Concerns at a Larger Scale
"The Northern Region Overview,
October 1998" published by the US Forest Service, Region 1, outlined the
following as their number 1 and 2 restoration priorities across the Region
based on ecological trends:
||Conversion due to conifer encroachment & fire exclusion|
||Change in density & aerial extent due to fire exclusion|
||Loss to blister rust, fire exclusion, mountain pine beetle|
||Change in age structure pattern due to fire suppression|
||Structural change, loss of grass due to fire exclusion|
|Groups of upland||
||Interface with dry conifer type & conifer encroachment grass/shrubs(Juniper/sage, due to fire exclusion (majority of big game winter range).|
|Bitterbrush/ bunchgrass, etc.|
|Riparian shrub/graminoid bottoms||
||Grazing shifted species composition to upland types due to stream channel changes|
Dry Douglas fir
II. VEGETATION POTENTIAL
In order to understand the role of vegetation in the landscape, we need to understand the types of, condition of, and potential for change in the plant communities in the Gravelly Landscape. In the section above, we described the types of vegetation currently occurring and some history related to how those types came about. In this next section, we will describe the makeup and ecology of those types to predict how vegetation might change in the future.
To accomplish this, we look at the physical and biological potential as a base for producing vegetation (mapped as Ecological Landscape Units) and the type of vegetation this base is likely to produce (mapped or described as Habitat Type Groups). Refer back to "Ecological Landscape Units" in an earlier section for a discussion of how physical and biological potential were used to describe basic land units. Literature cited in Appendix C.
HABITAT TYPE GROUPS
The climate and geology of the Gravelly Landscape has led to a mountainous area naturally diverse and fragmented. As a result, there are a great number and variety of plant communities found across the Gravelly Landscape. It would be impossible to describe the composition and ecology of each one in this document. To get a general feel for the vegetation found across the landscape, we have grouped plant communities based on structural and ecological similarities into habitat type groups. Within each habitat type group, a handful of communities generally dominate. These dominant communities will be used to help describe the vegetative structure, successional pathways and ecological impacts for the group as a whole. Information on the many other communities not specifically described is available.
Habitat types help us predict what a site is capable of growing as well as describing what IS growing. Habitat types are classified based on the climax plant community, which is the end result of plant succession and reflects the most meaningful integration of the environmental factors affecting vegetation. Use of the habitat type does not imply that an abundance of climax vegetation occurs in the present landscape. Actually, most vegetation in the landscape reflects some form of disturbance and various stages of succession towards climax. This method of classification, however, does not require the presence of a climax stand to identify habitat type. It can be identified during most intermediate stages of succession by comparing the relative reproductive success of species present with known successional trends and observing the existing undergrowth vegetation (Pfister and others, 1977). Furthermore, use of climax community names in habitat type classification does not imply that management should necessarily be for climax vegetation to optimize vegetation health. The vegetation on a site is only one element used in developing an overall assessment of the landscape's capabilities and societal desires.
Changes in plant communities occur over time as a result of natural processes and intervention by people. There has been considerable discussion and some disagreement between resource specialists on the interdisciplinary team on the role of disturbance processes in determining the types of, condition of, and potential for change in the plant communities in the Gravelly Landscape. This disagreement settles on the role and influence of fire, in particular, as a natural disturbance. The group agreed on the necessity of describing site capability and potential plant communities (using habitat type groups as a descriptor). In order to deal with the two viewpoints, the team developed two scenarios for describing how we got where we are today and what the potential for the future is. Scenario 1 is based on the assumption that plant succession is the controlling influence on potential plant communities, recognizing the obvious disturbances by humans and climate that have been recorded since 1940. Natural disturbance cycles like weather, insect and disease, and fire had less of an influence. Scenario 2 is based on the assumption that natural disturbance cycles, particularly fire, had a measurable effect on the distribution, composition and health of vegetation before settlement of the area by European descendant peoples. This assumption relies on interpreting fire scars, soil changes and historic journals and photos. It also assumes that these records of fire in specific instances can be used to infer a repetitive sequence of fires across the landscape.
The information was developed for both scenarios and compared to the existing condition to identify potential areas of concern, risks and trade-offs. The concerns, risks and trade-offs were weighed along with the various other values of the vegetation resource (soil protection, wildlife habitat, scenery, etc.) to describe a desired future condition of the vegetation resource. This comparison was done by interdisciplinary team representatives from each specialty and discipline and is documented in Chapter 3 - "Integrated Desired Future Condition".
Appendix C contains a detailed description of changes to expect for each habitat type group or subgroup over time, as developed for both the Climax Scenario and the Disturbance Scenario.
Habitat types were derived
from USFS East Slope Groups. Forested habitat types were then looked at
from the landscape level and categorized into several habitat type "groups".
The detailed habitat type group descriptions are broken out by those groups
A. NON-FORESTED HABITAT
Due to the mapping constraints at the landscape level we could not separate out the community type groups into the cover type categories with acceptable accuracy. For this write-up we have divided the non-forested HtG into two subgroups, grassland and shrubland. The grassland subgroup could be divide into three additional groups relative to soil moisture regimes. This is where accuracy could not be maintained in the mapping. Many of the habitat types and community types cross between the three moisture levels, especially the dry and moist grassland cover types. The moisture regimes could be mapped, but correlating these moisture levels with plant communities could not be completed.
Here is a general description of where the vegetation breaks may occur. The upland grass-herb and alpine-subalpine herb fall within the dry grass and moist grass cover type. The riparian/wetland herb falls within the wet grass cover type and will be described in the riparian group. The upland shrub group falls within the sagebrush/grass cover type. The upland grass-herb communities could be divided at the 6800' elevation. Below this elevation, the upland grass-herb could be placed in the dry grass cover type. Above 6800', the upland grass-herb communities could be placed in the moist grass cover type. The moist grass cover type can be further divided at the 9200' elevation. Above this elevation we begin to encounter the alpine-subalpine herb communities. Agricultural and urban cover types have generally developed within the dry grass and moist grass cover types. Some riparian/wetland herb communities also have been developed.
This HtG is characterized as those sites that support a mix of graminoids and herbs. Sites run from wet sedge meadows to very dry fescue slopes. These communities are found on all aspects but generally on level to only moderately steep slopes. The type is generally dominated by graminoids, but forb coverage can be quite variable between sites and between years. Shrubs may be present but in very low coverage. The majority of the grassland communities are commonly described as bunchgrass communities. Here, the grasses grow in clumps randomly spread across the area. The other main type is the sod forming communities. Here, the dominant graminoids are rhizomatous and form continuous mats of sod similar to a lawn. The majority of the sod forming communities are associated with higher moisture and typically are dominated by sedges or bluegrass. Dominate graminoids found across the landscape include: Idaho fescue, blue bunch wheatgrass, blue gramma, needle-grass, mountain brome, basin wildrye, tufted hairgrass and a handful of sedges. Forb composition is quite varied in the grassland communities. The mid elevation moist grasslands can be very diverse in the number of forbs present. Many sample plots will have over 20 species of forbs growing within a 1/10 acre area. Some of the more common species found include lupine, phlox, false dandelion, pussy-toes, bluebell, sandwort, cinquefoil, buttercup, milkvetch, point loco, rockcress and draba. The low elevation dry grasslands typically have fewer species and a higher amount of bare soil when compared to the moist and wet grasslands. The moist and wet grasslands generally have very little exposed bare soil and high amounts of litter cover. Wet grasslands are found in association with springs, seeps and high water tables on level to rolling topography.
The vertical structure of these communities does not vary greatly. Grassland communities run from six inches to just four or five feet in height. Most communities average two feet tall. The taller of the communities are generally found in wetland conditions and are dominated by cattail or reed grass. Basin wildrye is one of the few dryer upland species that may grow up to four feet tall. The horizontal structure of the grasslands can be quite variable across the landscape. This horizontal diversity comes from the intermixing of the various plant communities across a slope or valley bottom. Even within specific plant communities structural differences develop as various plant species dominate the small microclimates found behind rocks, in small depressions and other topographic variables.
Grasslands are found scattered throughout the Gravelly Landscape. This habitat type group tends to be the dominate vegetation in the valley bottoms and then again in the upper elevations. This group makes up approximately 28% of the landscape with 61% in public ownership.
Much of grassland area across the landscape is in a mid to late seral successional stage. In some areas due to past or current uses species diversity has changed or the dominate species have changed from what typically would have been found. These sites are in a low seral successional stage. For the grassland communities these changes can be relatively shuttle. The overall view of the community would still be one of a grassland. Only when one looks at what is actually growing on the site and in what proportions may a change be detected. Much of the agricultural land and urban areas have established on native grasslands. Here the changes to plant community are obvious.
Non-native species have become established in many of the grassland communities. Most exotic plants are nonevasive and can add to the overall diversity of the plant community. These species include timothy, smooth brome, and orchard grass. A small percentage of these exotic species are very aggressive invaders and can dominate plant communities to the detriment to soil, plant diversity and biomass production. The most destructive are the noxious weeds that have become established in the landscape. Most plants officially classed as noxious have the potential to dominate most grassland communities. As an example, spotted knapweed, the most common noxious weed in the Gravelly Landscape, can overtake a grassland community to the almost complete exclusion of all other plant species. There is a tremendous loss in plant diversity and ecological function when his occurs. It has been shown that spotted knapweed can establish in healthy grasslands without the need of soil disturbance. In the absence of control, noxious weeds will continue to spread and eventually dominate plant communities in the landscape. Noxious weed species in this landscape include knapweed, leafy spurge, Canada thistle, and dalmation toadflax. Currently, most exotic plant infestations are located in the valley bottoms, associated with roadways and intensively managed ground such as towns, subdivisions and cropland.
Heavy livestock grazing in the early part of the century affected changes in the plant communities. Introduction of exotic plants such as Kentucky bluegrass, timothy, crested wheatgrass and orchard grass have changed the overall plant composition found in many of the grassland communities. These changes are obvious at the stand level, but the overall appearance of the site and the ecosystem functioning of the plant community has not changed. These sites still appear as open grasslands and plant diversity is generally similar to what should occur. Some of these changes have been intentional with the goal of increasing forage production. This has primarily occurred on the private lands in the landscape. Most of the agricultural lands in the landscape developed on native grasslands. It is general agreement that climax grassland communities produce less forage than if the site were maintained at a mid to late seral stage. Much of the grassland area is managed to optimize forage production. This type of management will generally prevent these sites from reaching a climax condition.
Shrublands are found throughout the landscape. At 46%, it covers the largest area of any habitat type in the Gravelly Landscape with 67% in public ownership. A handful of sagebrush species dominate this vegetative type making up approximately 90% of this subgroup. Other shrubs which characterize additional habitat types include, four wing saltbush, mountain mahogany, greasewood, bitterbrush, shrubby cinquefoil, skunk brush sumac, and rabbitbrush. Most communities dominated by these species are found on drier sites on lower slopes or in valley bottoms. Sagebrush communities tend to be on moister sites dominating higher valley bottoms and from lower to upper slopes in the mountains. The dominant shrubland community in this landscape are dominated by mountain big sagebrush. Well over 80% of the shrubland habitat types are dominated by this sagebrush taxa. For general reviews of the ecology of sagebrush/grasslands see McArther and others 1990, Peterson 1995, McArther & Welch 1986, Tisdale and Hironaka 1981, and Utah State University 1979.
Shrubland communities vary in shrub coverage. Canopy coverage can range from less than 5% to over 70%. Generally, the higher the coverage of shrubs the more mature the community. Those stands currently having less than 5% canopy cover will, over time, increase their shrub cover. Drier sites tend to have lower coverage of shrubs than more moist sites. In southwest Montana, most shrubland communities are dominated by only a single shrub species. Rarely will you find sites where two species codominate the site with equal coverage. Five or more species of shrubs may occur on a site but, except for the dominant species, all others usually each have less than 1% canopy coverage.
The structural diversity of the sagebrush/grass cover type is controlled by the density of sagebrush cover. With sagebrush generally growing only 1-4 feet tall, the vertical diversity in this cover type does not vary greatly. Basin big sagebrush is the exception, it can grow over eight feet tall. Horizontal diversity is highly affected by the density or canopy cover of sagebrush plants. Horizontal diversity is described as if you are viewing from a distant slope or were looking down from a hill top. The appearance of a site with 0%-5% canopy cover is one of an open grassland with scattered shrubs. The shrubs may be scattered individually throughout the area or found in small clumps interspersed across the site. As canopy cover increases, up to 15%, the general appearance of the site changes to a shrub dominated site with scattered patches of grassland. The open grassy patches are still an obvious component and may be interconnected. When canopy cover increases over 15% to 20% the open patches become smaller and will eventually become inconspicuous. These sites appear as dense shrubland stands with few small open pockets of grasses and forbs. The open pockets generally are isolated and do not interconnect. As site distance decreases and topography flattens, the general appearance will compress toward the higher canopy covers. Sites will seem to have heavier canopy covers than they actually do. Sites with canopy covers of 10% to 15% will appear as heavy stands of shrubs with few grassy openings. Horizontal diversity is further enhanced by the mixing of the various canopy covers across the broader landscape.
The understory species composition in the sagebrush communities are very similar to the grassland types. In the absence of shrub cover, most sites would be indistinguishable from the grassland habitat types that would grow on similar sites. Dominate graminoids found include: Idaho fescue, blue bunch wheatgrass, blue gramma, needle-grass, mountain brome, basin wildrye, tufted hairgrass and a handful of sedges. Forb composition is quite varied in the shrubland communities. The mid elevation moist shrublands can be very diverse in the number of forbs present. Some of the more common species found include lupine, phlox, false dandelion, pussy-toes, bluebell, sandwort, cinquefoil, buttercup, milkvetch, point loco, rockcress and draba. The low elevation dry sites typically have fewer species and a higher amount of bare soil when compared to the moist and wet grasslands.
Due to past management activities, a variety of non-native plant species have established themselves in the Gravelly Landscape. Smooth brome, timothy and Kentucky bluegrass are three species that have been widely introduced throughout the western United States. These species, and others, have become naturalized in a variety of plant communities and should now be considered a natural component of these systems. The presence of these species within a community does not necessarily mean a loss of function within a community. These species can and do maintain soil protection, litter accumulation and forage production. They can serve the same functions as native species. These species are here to stay and a new equilibrium will be established within these communities.
As with the grassland communities, the establishment of noxious weeds is the most serious impact we are seeing in shrubland communities. Due to the dry and more open nature of these vegetative communities, they have a higher potential for noxious weed invasion than many other types. Most plants officially classed as noxious have the potential to dominate the understory plants in shrubland communities. Shrubs, being relatively long lived and taller than the surrounding graminoids and forbs, can maintain themselves on a site when noxious weeds like spotted knapweed invade. There is a tremendous loss in understory plant diversity and ecological function when knapweed takes over a site. In the absence of control, noxious weeds will continue to spread and eventually dominate most plant communities in the landscape.
Currently, the Gravelly Landscape is dominated by this vegetation subgroup. Current mapping has it covering 46% of the landscape; this is the highest coverage for any vegetation type in the Gravelly Landscape. Sixty seven percent of this group is in public ownership. Accurate mapping of shrub canopy cover was not possible at this map scale. Overall in review of this cover type across the landscape, we see the majority having a relatively dense cover of shrubs, generally over 10-15% canopy cover. Understory vegetation is similar to what would be expected in this condition. Non-native graminoid species have established in many communities. The extent of noxious weed invasion is sporadic across the landscape. The heaviest concentrations of noxious weeds currently are found in the valleys.
Riparian Zone Habitat Type Group
The riparian cover type encompasses all riparian shrub, deciduous and coniferous plant communities. This cover type includes the riparian/willow cover type map categories. Much of this cover type is located along the many streams across the landscape. Most riparian sites cover a relatively small area and were not mappable at the landscape level. The dominant habitat types, community types, and plant associations found in the Gravelly Landscape are listed below. For a more complete listing of riparian plant communities found in southwestern Montana see Appendix C.
Riparian areas make up less than 2% of the Gravelly Landscape. This coverage greatly underestimates the importance of these communities. The riparian areas found across the landscape are quite varied and include lakes, ponds, streams, fens, marshes, springs and seeps. The vegetation found along and within these areas is also quite varied. Most plant species found in riparian areas are there due to their higher moisture requirements. Changes in the water regime will cause a change in the vegetative composition of a site. The health of riparian vegetation is intricately tied to the condition and status of the hydrologic functioning of the creeks, springs and marshes. Riparian areas support the greatest diversity of plant and animal species of any vegetative community. They provide food and water in a primarily very dry landscape. Streams provide a relatively secure area for wildlife migration through the area and between landscapes.
Streams are the dominant type of riparian area in the Gravelly Landscape. The larger rivers have a variety of plant communities growing along their banks. This is where we find the majority of the cottonwood forests. Mountain streams tend to be dominated by coniferous forested communities; this is due to the relatively high gradient of the streams and narrow valley bottoms limiting the extent of the riparian influence. Spruce is the dominant species in these communities. Subalpine fir, white bark pine, Douglas fir and lodgepole pine are also found on these sites, but in lesser amounts.
Many streams have shrubs or graminoids as the dominant vegetation. These sites are generally where the stream gradient is low and the valley bottoms wide, allowing the formation of a larger flood plain. Willows are the principle shrub species of the riparian areas. Alder and birch are found less frequently. The most common willow species are Geyer, Booth, Drummond, Bebb and Wolf. Ground cover is quite varied but usually dominated by graminoids such as water sedge, beaked sedge, bluejoint reedgrass, Kentucky bluegrass and mountain brome. The last two species have become dominant on many sites due to past disturbances such as mining and livestock grazing. A whole host of forb species are found in the various riparian communities.
Wet meadows and marsh communities generally are found scattered across the landscape and do not cover large areas. The Centennial Valley is an exception. Here, these communities dominate much of the valley floor. Red Rock Lakes National Wildlife Refuge encompasses a large mix of lakes, marsh and wet meadows. These communities are dominated by graminoids and willows.
Due to the generally deep soils and abundant water, riparian areas tend to be quite resilient to disturbance. Typical riparian vegetation has deep, fibrous root systems that form a protective mat in the soil. This mat of roots is very resistant to damage from floods and other localized disturbances. If the vegetative composition changes and becomes dominated by more dry site species, plants that generally have shallower, less dense root systems, soil protection is greatly reduced. The vegetation in functioning riparian areas is quite stable. There are relatively minor changes in the plant composition unless there is a large destructive disturbance. Most riparian species are long lived perennials that resprout if the above ground portion is killed.
Due to the mapping constraints,
it is not possible to describe the riparian vegetation in specific percent
coverages. Many valley bottom wet meadows have been converted to agricultural
uses. Most streams and meadows have some degree of livestock use. Past
heavy livestock use along with stream diversion and impoundments have caused
changes in the water regime on many sites. The vegetation on these sites
show a higher proportion of dry site species than what would be expected.
In localized areas, steams were placer mined. These sites still reflect
the complete disturbance of the streambed and the potential for the site
Aspen Habitat Type Group
The aspen cover type is found scattered in small patches across the entire Gravelly Landscape. This cover type is one of the rarer plant communities found in the Gravelly Landscape. Due to it being relatively rare on the landscape and one that is being lost, it has been separated out as an individual group. Most aspen stands would fall within one of the forested habitat type groups. Aspen is a seral species that is dependent on disturbance to maintain itself. Sites dominated by aspen generally would be classed as being in an early seral stage of succession. Relatively few aspen stands are maintained as a climax aspen community. These are usually found within larger stands of sagebrush/grass or grassland communities. The dominant community types and plant associations found in the Gravelly Landscape are listed below. For a more complete listing of aspen plant communities found in southwestern Montana see Appendix 1.
Aspen are found scattered throughout the Gravelly Landscape. The heaviest concentrations are found on the east side of the landscape in the Gravelly Mountain range. Aspen stands comprise only a small percentage of the total vegetation cover in the landscape but are quite vital to the overall diversity of the area. This habitat type group includes the aspen and aspen/conifer mix cover types. Technically, the sites currently supporting aspen or aspen/conifer mix would fall within one of the forest habitat type groups. Due to the overall importance of aspen on the landscape, we have made it a separate group even though it crosses all vegetation type boundaries.
Understory vegetation can be quite varied in aspen stands. The understory can be multi-layered with a shrub, graminoid and forb layer or be restricted to only a graminoid or forb layer dominated by a few species. Common plant species found in these types include mountain snowberry, Oregon grape, mountain brome, blue ryegrass, sticky geranium and wyethia. Many stands also contain scattered conifers, generally spruce, subalpine fir and lodgepole pine. The condition of the aspen in the area is quite varied. Aspen is maintained on many sites by natural catastrophic events such as fire. In the absence of such events, the natural succession for the sites would be the replacement of the aspen with conifer or sagebrush/grass vegetation. This group makes up only 1% of the landscape with 66% in public ownership.
Some factors affecting the current aspen condition are: (1) aging - the general stand age averaging 70+ years, (2) vegetation succession to conifer or sagebrush/grass cover types, and (3) livestock/wildlife utilization. Studies completed in the southern Gravelly area using remote sensing and geographic information systems showed a 45% decline in aspen over a 45 year period (Wirth and others 1996). The majority of the aspen was replaced by conifers. Field reconnaissance confirm these results. Surveys have shown over 70% of the aspen stands in jeopardy of being lost in the near future. Many stands have no substantial or healthy regeneration and nearly all have conifers established in the lower canopy. Many stands are at or near the point of break up and will be replaced by conifers. A small percentage of aspen stands will be replaced by a sagebrush/grass cover type. These are generally stands that are isolated within large areas of sagebrush/grass vegetation with poor availability to conifer seed sources. Very few acres of sapling or pole sized aspen stands have been found across the landscape.
The poor condition and the loss of aspen stands has also been documented in the Cliff Lake RNA (Mueggler 1988a) located in the southeastern corner of the landscape. In reviewing photographs taken in 1946, Mueggler found a marked reduction in aspen, both inside and outside the RNA. Stands that were quite large and healthy in 1946 had deteriorated to stands of scattered unhealthy trees with very weak, suppressed regeneration in 1988. Mueggler noted that heavy browsing of aspen suckers and barking of the trees were obvious. These types of damage to aspen can result in the deterioration of the stand and prevent its re-growth. He reports, "Either cattle or game, or both, could be responsible for this damage on the allotment, but deer, elk, or moose are undoubtedly the responsible agent within the Natural Area."
Of the mapped aspen, 62% currently have a significant coverage of conifers. These stands have a very high probability for the loss of the aspen component in the near future. The remaining 38% are relatively dense stands of aspen. These are generally healthy, vigorous, mature stands. Most still have some conifers established in the understory. The conifers are just small saplings and have not affected the vigor of he stand at this time.
B. FORESTED HABITAT TYPE GROUPS
Habitat types were derived from the Forest Service East Slope Groups. Forested habitat types were then looked at from the landscape level and categorized into these habitat type groups. These particular habitat type groups are based on standard grouping which expresses general habitat characteristics such as Warm and Dry, or Cool and Moist. The vegetation team has gone further by selecting site characteristics that describe these groups as they occur specifically in the Gravelly Landscape - linking them to elevation, aspect breaks and the dominant habitat type in each group. A habitat type group map is also available to denote locations of each habitat type group as they occur in this landscape.
Within each habitat type group, a handful of communities generally dominate. These dominant communities will be used to help describe the vegetative structure, successional pathways and ecological impacts for the group as a whole. Information on the many other communities not specifically described is available.
FOREST HABITAT TYPE GROUPS
|North - cool/wet||East - cool/moist||South - warm/dry|
|11,000 ft. +
|11,000 ft. +
|11,000 ft. +
|8,000 - 11,000
|8,200 - 11,000
|8,200 - 11,000
|7,500 - 8,000
|7,500 - 8,200
|7,900 - 8,200
|7,000 - 7,500
|7,000 - 7,500
|7,000 - 7,900
|5,500 - 7,000
|5,500 - 7,000
|6,500 - 7,000
The following table provides a summary of each Habitat Type Group: setting, size, condition as affected by activities, and acres in each major forest type by stand structure. Stand structures are described as follows:
|Infant or Colonization - young seedling or sapling trees less than 20 feet tall|
|Juvenile - pole size trees from 20 feet to full grown.|
|Gold - mature or overmature trees.|
The following table provides a summary of each Habitat Type Group: setting, size, condition as affected by activities, and acres in each major forest type by stand structure. Appendix C contains detailed description of ecology and condition of each HTG.
|Habitat type group A - warm and very dry. Covers 12,000 acres in this landscape, which is less than 1% but it represents 3% of the forested areas. It is the 6th largest forested HTG. Activities: grazing intensity on elevations below this HTG historically have been moderate to intense in the past 130 years. Stocking levels are considerably lower since the 1960's. With use of finer fuels by livestock, population increases in the valley, and conversion of bottom lands to agricultural production, fires were less likely to reach historic sizes.|
|Tree Species||Acres of Infant or Coloniz.||Acres of Juvenile||Acres of Gold|
|Douglas-fir||30 (less than 1%)||1680 (14%)||3470 (30%)|
|Other conifers||420 (4%)||2060 (18%)||3670 (31%)|
|Aspen/conifer||0 (less than 1%)||150 (1%)||210 (2%)|
|% TOTALS||About 4%||33%||63%|
|Habitat type group B - similar to HTG A in temperature but is not as dry as the lower elev. group. Its the 4th largest forested HTG. More frequently found in the west and north sides of the landscape. Comprises 40,000 acres or about 2% of the area and represents about 10% of the forested area. Activities: Grazing is common but less productive than nonforest types. Insect and disease levels are moderate (scattered bark beetle and spruce budworm in the 1980's). Historic logging was more common than HTG A since the quality of timber is higher. It occurred where there was an opportunity for products like mine timbers, fuelwood, post and poles and barn or house logs. Recent timber harvest took place on private and public land from 1970's to present, but the major activity was in the higher elevation portion of this vegetation type.|
|Tree Species||Acres of Infant or Coloniz.||Acres of Juvenile||Acres of Gold|
|Douglas-fir||269 (less than 1%)||6888 (18%)||14,543 (39%)|
|Other conifers||958 (3%)||5708 (15%)||8336 (22%)|
|Aspen/conifer||34 (less than 1%)||94 (less than 1%)||525 (1%)|
|% TOTALS||About 4%||34%||62%|
|Habitat type group C - warm and moist. It is the smallest of the HTG's at 600 acres. Vegetation is a mix of Douglas-fir on south and west aspects and Douglar-fir/lodgepole pine on north and east aspects. Activities: Some grazing of fine fuels, conversion to agriculture, and subdivision activity has affected this habitat type group in minor ways.|
|Tree Species||Acres of Infant or Coloniz.||Acres of Juvenile||Acres of Gold|
|Douglas-fir||13 (2%)||127 (22%)||355 (62%)|
|Other conifers||35 (6%)||(0%)||39 (7%)|
|Aspen/conifer||2 (less than 1%)||(0%)||(0%)|
|Habitat type group D - cool and moist. It is the 3rd largest of the HTG's at 53,000 acres total. Comprises 3% of total land area and 14% of the forested area. Vegetation is a wide variety of conifer and understory species. Activities: there has been little or no major natural disturbances during the last 50 years but some human-caused disturbances.|
|Tree Species||Acres of Infant or Coloniz.||Acres of Juvenile||Acres of Gold|
|Douglas-fir||116 (less than 1%)||7226 (14%)||20,052 (38%)|
|Other conifers||833 (2%)||10,105 (19%)||12,657 (24%)|
|Aspen/conifer||2 (less than 1%)||735 (1%)||1221 (2%)|
|Habitat type group F - located mostly in the Gravelly and Greenhorn Mts. Typically the lower subalpine/lodgepole pine stands. It is the largest HTG in the landscape, representing almost 8% of the total area, 40% of the forested area. Activities: this HTG has the highest degree of timber harvest . However, this is insignificant landscapewide, with less than 1% of the area in "Infant" (seed sapling) category. Most of these occured in the last 20 years or so. A maximum of 3/4 of the 22% juvenile could be related to harvest in the past 20 to 50 years, up to 25,000 acres over 50 years. The Greenhorn/Gravelly ELU has the highest % at 23% infant/juv trees in this HTG. Periodic beetle epidemics have also had a dramatic effect on existing stand structure.|
|Tree Species||Acres of Infant or Coloniz.||Acres of Juvenile||Acres of Gold|
|Douglas-fir||93 (less than 1%)||14,400 (9%)||31,696 (20%)|
|Other conifers||825 (less than1%)||19,349 (12%)||84,338 (54%)|
|Aspen/conifer||40 (less than 1%)||1606 (1%)||4528 (3%)|
|Habitat type group H - generally cooler than HTG F. It is the 5th largest in the area at 21,000 acres, contains 1% of the lands area and 5% of the forested area. Activities: This HTG has been affected by timber harvest, to a lesser degree than HTG F, as much as 3,000 acres over the last 50 years.|
|Tree Species||Acres of Infant or Coloniz.||Acres of Juvenile||Acres of Gold|
|Douglas-fir||0 (0%)||1359 (7%)||3532 (17%)|
|Other conifers||228 (1%)||2497 (12%)||11,345 (56%)|
|Aspen/conifer||22 (<1%)||257 (1%)||1187 (6%)|
|Habitat type group I - cold and moist with upper subalpine and timberline habitat types. It is the 2nd largest HTG with over 105,000 acres, 5% of the total area and 27% of the forested area. Activities: the existing stands are a result of little or no activity or disturbance during the last 50 years. Lack of fire and the expected increase in white pine blister rust mortality threatens the future of whitebark pine in this HTG.|
|Tree Species||Acres of Infant or Coloniz.||Acres of Juvenile||Acres of Gold|
|Douglas-fir||27 (<1%)||841 (<1%)||4845 (5%)|
|Other conifers||733 (<1%)||19,132 (18%)||80,277 (75%)|
|Aspen/conifer||10 (<1%)||127 (<1%)||759 (<1%)|
Linking Habitat Type Groups to Ecological Landscape Units
Habitat type groups tend
to reflect underlying landforms, precipitation, elevation and aspect. These
habitat type groups were an important element in defining the Ecological
Landscape Units mapped in the Gravelly Landscape. Potential vegetation
in these ELU's can be characterized by looking at the distribution of habitat
type groups within each ELU. This is portrayed in the following bar graphs
and Map #14.
Also see "Ecological Landscape Units: in the first section of this Chapter.