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Shrub-Steppe Conservation Prioritization in Washington State


by George Wooten





Prepared for


Kettle Range Conservation Group

www.kettlerange.org



P.O. Box 150

Republic, WA 99166

509-775-2667


35 W. Main, Suite 220

Spokane, WA 99201

509-747-1663


We graciously acknowledge the support provided in the preparation of this report by the following organizations
The Kongsgaard-Goldman Foundation

The Bullitt Foundation
Shrub-Steppe Conservation Prioritization in Washington State

Kettle Range Conservation Group

www.kettlerange.org
Contents

Cover photo: Washington Native Plant Society members attending a botany foray on Steamboat Rock above the Columbia River, Spring, 2002.


I. Executive Summary

II. Background

III. Study Methods

IV. Results

V. Discussion

VI. References

Appendix A - Technical Procedures

Appendix B - Site descriptions



Appendix C - Photographs
I. Executive Summary
At a time when many Northwest environmental organizations are primarily concerned with protection of forests, shrub-steppe lands of the Columbia Basin are quietly slipping away.
Shrub-steppe lands (literally, shrub-grasslands) of the interior Columbia Basin, or Columbia Plateau, comprise the northern tier of the semi-arid and essentially treeless biome that covers much of the interior west between British Columbia and Mexico.
The natural history of the Columbia Basin led to the development of many, diverse communities typically dominated by shrubs or grasses that are specialized for living in harsh, dry climates on a variety of soils. Many other species have adapted to these conditions, including invasive species which have fundamentally altered the function of the ecosystem, much to its and our detriment.
Shrub-steppe habitats of Washington have been classified into many types based on major factors that include soils, soil moisture, geology, topography, temperature, light intensity, precipitation, snow, frozen ground, and wind speed and duration. For general discussions, six generalized habitats can be recognized: (1) standard, (2) lithosols, (3) sand dunes, (4) talus, (5) meadows, and (6) saline soils.
Shrub-steppe habitats are valuable for many reasons: as a cultural resource both for native and white Americans; as an economic resource, as viable habitat for species dependent on shrub-steppe, as recreational opportunities and as educational opportunities. Shrub-steppe lands provide critical habitat for a number of species of plants and animals, many of which are in decline.
Shrub-steppe lands are being lost due to a number of factors notably including conversion to agriculture, overgrazing, altered fire regimes and alien species invasion. The degree of degradation of shrub-steppe lands is an over-riding constraint in determining which lands deserve priority for preservation. In many cases, a misleading impression is given by figures which suggest large areas of Columbia Basin shrub-steppe remain, when in fact much of this land is so degraded as to be beyond restoration or ecological value. Part of this is due to the disparity between maps based on potential vegetation with that of the actual vegetation. In other situations, the ability to reverse deleterious changes to shrub-steppe communities may not be practically feasible. Some plant communities have such highly altered ecological processes that passive restoration efforts involving mere removal of the causative agent would be ineffective.
Thus, measures of ecosystem value need to incorporate both negative attributes such as degraded condition along with positive attributes such as diversity and rarity.
The purpose of this report includes: (1) to initiate shrub-steppe conservation prioritization efforts; (2) to map the different shrub-steppe habitat types; (3) to determine the extent of shrub-steppe habitats; (4) to determine the ecological integrity of shrub-steppe habitat types; (5) to determine the ownership status of shrub-steppe habitats; (6) to determine the relative degree of long term protection of shrub-steppe habitat types; and (7) to develop a decision matrix for new conservation acquisitions and easements.
The first objectives are intended to lay the groundwork for subsequent objectives. Our society can no longer afford to designate conservation areas on a piecemeal basis. Land conservation efforts require that limited funds be spent where they will do the most good; every acquisition comes at the cost of another parcel that gets developed instead.
The first two project objectives are complete. Estimates of past shrub-steppe extent found that shrub-steppe vegetation originally covered 24,437 square miles in Washington or about 36% of the land surface. The current extent of Washington’s shrub-steppe as mapped is approximately 11,315 square miles (46.3% of historic), with the vast majority of loss being due to agriculture (98%), followed by development.



The above map image shows the current extent of shrub-steppe lands in Washington (in light shades) along with lands converted to agriculture or development (blue).


A number of assumptions went into the calculations of past and present shrub-steppe extent, such that the figure of 11,315 square miles or 46.3% of remaining shrub-steppe is too optimistic. At this point, other factors that would lower this figure include the following: (1) the input data is ten years old; (2) the historic extent of the shrub-steppe did not include small peripheral areas; (3) agricultural areas were defined to be 100% converted--other lands counted as shrub-steppe were severely degraded rangelands, fallow fields, weed infestations and agricultural areas with less than 100% conversion. To account for these factors, further research in vegetation typing and condition mapping needs to be accomplished.
The results of the analysis of administrative ownership of shrub-steppe lands was informative in that it revealed that the four groups of agencies analyzed are doing a poorer job of protecting shrub-steppe habitat than the other ownerships that weren’t analyzed (including private lands). The overall percentage of shrub-steppe conservation on these lands was a mere 15.6%, less than half of the percentage of the norm. If true, this reflects badly on the role of these agencies as land stewards. Only the Coulee Dam RNA, at 69.2% shrub-steppe remaining, was significantly above the norm. It was unexpected to find that the large Colville and Yakama Indian Reservations, with their vested interested in native cultural use of shrub-steppe lands, were below the norm in shrub-steppe preservation.
These findings need corroboration, and if true, some adjustments to management or management goals may be in order. In any case, the findings should be a stimulus toward further elucidation of the ownership and management of shrub-steppe lands and which shrub-steppe lands are currently receiving protection.
Further examination of the results of this analysis showed that the results are overly optimistic in portraying roughly half of the original shrub-steppe lands of Washington as intact. Many of the remaining shrub-steppe lands are poor condition without much ecological value. Field examination of sites on the layer of existing shrub-steppe revealed examples of severe degradation.
The maps used do not depict shrub-steppe plant associations beyond the regional scale. None of the shrub-steppe areas mapped in this analysis are sufficiently typed from an ecological point of view. Some of the rare plant associations and species are already gone forever. Thus, it is premature to make conclusions about the ability to prioritize conservation efforts without having more information on condition and community types.
This report marks the beginning of a more detailed project to prioritize shrub-steppe conservation. The remaining objectives of this study are still underway. Toward that end, important objectives that need the most work are (1) classification of shrub-steppe vegetation with higher reliability, resolution and detail; and (2) mapping land condition; and (3) analysis of overlays of shrub-steppe layers onto more detailed maps of administrative ownerships.
Our conclusion is that too little information currently exists for making rational shrub-steppe conservation decisions. The fact that land acquisitions are ongoing means that such decisions are at risk of being inappropriate or ineffective for the goal of preserving shrub-steppe habitat types.
However, the remaining information gaps could be filled in to some extent without a great expense. What remains to be accomplished is a study that identifies more details of (1) the condition of shrub-steppe lands; (2) the type of plant community; and (3) the land ownership. We propose that such studies be supported in Washington. This is an urgent need, but nonetheless an affordable one, which should be given attention to completion in the near future.
II. Background
At a time when many Northwest environmental organizations are primarily concerned with protection of forests, shrub-steppe lands of the Columbia Basin are quietly slipping away. A better understanding of the nature and function of shrub-steppe ecology is necessary to facilitate conservation efforts. What are shrub-steppe lands, how did they arise, how have they been altered, and why are they important? The answers to these questions give the necessary background for undertaking the challenge of protecting and preserving shrub-steppe lands for the benefit of future generations.
A. What are shrub-steppe lands?
Shrub-steppe lands of the interior Columbia Basin (also called the Columbia Plateau) comprise the northern tier of the semi-arid and essentially treeless biome that covers much of the interior west between British Columbia and Mexico. In Washington, the dominant vegetation is typically made up of various shrubs such as tall sagebrush (Artemisia tridentata), antelope bitterbrush (Purshia tridentata), rabbit brush (Chrysothamnus), winter fat (Atriplex) or other species of sagebrush (A. arbuscula, A. rigida). Grasses sometimes play a prominent role in these communities, including bluebunch wheatgrass (Pseudoroegneria spicata), Idaho fescue (Festuca idahoensis), needlegrasses (Stipa spp.) and Sandberg’s bluegrass (Poa secunda). When grasses dominate, the lands are technically referred to as steppe. In addition, a diverse mixture of other plants and wildlife have developed within shrub-steppe habitats where they can take advantage of the plentiful sunlight and relative abundance of living space. Vegetation assemblages containing higher abundances of broadleaved forbs such as arrowleaf balsamroot (Balsamorhiza sagittata) are termed meadow-steppe. These types become prominent on the periphery of the Columbia Basin (Franklin and Dyrness, 1973), where the shrub-steppe grades into forested communities.
Much of our current understanding of Columbia Basin shrub-steppe ecology is due to Daubenmire’s (1970) application of a vegetation classification system based on the presence or absence of potential climax indicator species. His classification system grouped dominant vegetation types into a series of related plant associations, each arranged along a gradient of tolerance to limiting factors such as soil depth, precipitation or temperature. For instance, deep soils are a prerequisite for communities dominated by deep-rooted Idaho fescue (Festuca idahoensis), whereas shallow, jointed basalts limit growth to characteristic communities dominated by rock sagebrush (Artemisia rigida). Intermediate between these extremes plant species respond variably to form discreet communities that make up the various vegetation series.
Daubenmire determined that as a group, Washington’s shrub-steppe lands (literally, shrub-grasslands) are an artificial, descriptive aggregate, and that true steppe in the European sense, i.e., lands dominated by narrow-leaved grasses, were absent from his study area. This report focuses on Washington’s shrub-steppe, however much of the discussion applies throughout the interior west.
Taylor (1992) divided the shrub-steppe into six generalized ecological zones, each with a characteristic flora: (1) standard, a productive zone characterized by a lack of extremes, and which has been the most extensively lost to agriculture; (2) lithosols, with shallow basalt bedrock soils; (3) sand dunes; (4) talus; (5) meadows, moister areas that typically occupy depressions and; (6) saline soils, found in areas of low precipitation where mineral salts have accumulated on the soil surface.
In terms of both areal extent and ecological importance, one of the most significant plant communities with relevance to shrub-steppe lands is that of the lower ponderosa-pine (Pinus ponderosa) zone, also called the ponderosa pine-bunchgrass zone (Krajina, 1965; Brayshaw, 1965; Murphy, 1994; Arno and Hammerly, 1977). Ponderosa pine is important or prerequisite for a myriad of other species; in some habitats it is a keystone species which controls the development of the entire plant community. The transition zone between ponderosa pine and shrub-steppe is variable. In some cases the interface may be a gradual ecotone, in which case the boundary is somewhat arbitrary; in other cases the interface may form a mosaic (Hall, 1967). The lower pine zone presents a problem in landscape classification, not only because of the effect this has on area and ownership calculations, but also because the boundary between these communities is a dynamic one subject to change over time. The interface between ponderosa pine and shrub-steppe has moved significantly since white settlement began, partly in response to fire suppression and livestock grazing, but also due to long-term changes in climate and natural disturbances such as disease.
Unfortunately, no reliable map yet exists of Washington’s shrub-steppe that gives even a general level of detail at a meaningful scale. All existing maps incorporate assumptions that render accurate vegetation typing results as tenuous. For instance, it is difficult to tell healthy sagebrush communities from ones covering old plowed fields using just aerial photography. Therefore, the purpose of this report does not include classification of shrub-steppe vegetation beyond first approximations.
The purpose of this report is threefold: (1) to determine the extent of shrub-steppe lands as an aggregate group; (2) to serve as an initial step toward further conservation prioritization efforts which will require more detail to discriminate between habitat types and their relative degree of preservation; and (3) to determine as the ownership and preservation status of shrub-steppe lands.
It is important to consider shrub-steppe conservation regionally and over the long term. Knowledge about the location, extent and condition of shrub-steppe lands is indispensable for effective prioritization of preservation needs, as well as for the design of conservation programs which could conceivably involve land set-asides, conservation easements, or protective management designations.
B. How did Washington’s shrub-steppe arise?
The composition of shrub-steppe ecosystems is an important consideration in conservation of a representative subset of communities; this in turn is dependent on site conditions. The primary rock type within the Columbia Basin of Washington is the Columbia River Basalt Group, which originated from a series of basalt flows that erupted between 17 million and 6 million years ago from swarms of feeder dikes. The flows spread across a low-relief area of approximately 63,205 square miles and up to 4,000 meters (13,000 feet) thick, where they now abut mountains to the west, north and east. Following the eruptions, the basalts were faulted and folded to reliefs of up to 450 m (1,500 feet) (Campbell and Reidel, 1991, Tolan et. al., 1989, Griggs, 1978). The geological youth of these basalt rocks, their relative lack of breakdown and alteration, and their high degree of exposure at the surface, all provide a strong limitation on the species composition and physiognomy of vegetative communities.
Surrounding the Columbia basalts on three sides is a diversity of rock types, with the oldest types lying to the east (Griggs, 1978). To the west and north of the Columbia basalts, mountain ranges have arisen over the millennia through a complex of processes that include uplift, erosion, faulting, terrane accretion and volcanism (Stoffel et. al., 1991; Griggs, 1978, Tennyson and Cole, 1987). In contrast to the relatively shallow relief of the Columbia basalts, land at the margins of the flows exhibit greater variation in topography soils and microclimate; in response, landscapes along the edge of the Columbia Basin have developed with a high degree of biological diversity between and within plant communities. The biodiversity along the margin of the Columbia Basin is strongly manifest along tributary valleys and the Columbia River proper where shrub-steppe communities interfinger with montane and riparian communities that receive greater moisture and occupy different soils.
Species makeup and even entire communities have apparently changed radically since the end of Pleistocene Epoch and retreat of the ice sheet (Pielou, 1991). Evidence from pollen spectra measured in dated cores from the Okanogan Valley area indicate that sagebrush and graminoids were dominant while arboreal species were poorly represented during the first millennium after the ice retreated approximately 10,000 years ago (Mack et. al., 1989; Mack et. al., 1978; Alley, 1976). However extensive research indicates that these prehistoric plant assemblages have no modern analogue, even in the case of apparent sagebrush-steppe dominants (Mack and Bryant, 1974). The vegetative communities we know today began their formation about 6,700 years ago following the end of several thousand years of warm, dry climate, the hypsithermal (Pielou, 1991). From this point they may have attained their approximate present makeup by 3,000 years ago (Mack et. al., 1978; Alley, 1976; Hansen, 1940).
The Ice Age was also a time of massive meltwater flooding which radically altered the geology and vegetation patterns over the Columbia Basin. The most spectacular meltwater floods were the Spokane Floods, also known Missoula floods for the glacial lake of their origin, or as Bretz floods, after J Harlan Bretz, their discoverer. Bretz (1959) first discerned that the geology of Washington’s aptly named channeled scablands must have been due to flooding, the origin of which was due to periodic failures of ice dams holding back 2000 km2 of water in glacial Lake Missoula (Waitt, 1985).
The effect of the Spokane floods was profound. A network of meltwater channels was cut through bedrock hundreds of feet deep and as many miles long, reaching from the Idaho panhandle to the mouth of the Columbia and even into Oregon. The floods moved huge walls of rock and mud across the state, leaving behind a landscape of scoured bedrock, dry waterfalls, alluvial gravels the size of trucks, anomalous rock deposits left by rafted ice blocks, and ripple bars with 30 meter crests. Over the last 10,000 years, these flooded landscapes developed into unique plant communities, possibly even producing new species, for instance Hackelia hispida var. disjuncta (Hitchcock et. al., 1979; Gentry and Carr, 1976), which only occurs in large meltwater coulees.
In some areas the flood sediments have been locally reworked by wind to form dune sands or loess deposits (Reidel et. al., 1992). Another prominent soil feature which covers hundreds of square miles of central Washington soils are regularly spaced low mounds of fine soil atop a matrix of scoured basalt, known as biscuit-swale topography. This type of patterned ground has many competing hypotheses to explain its origin, for example intensive frost action associated with a periglacial climate (Kaatz, 1959).
These natural events combined to enable the formation of what we know of as the shrub-steppe biome of the Columbia Basin. Arno and Hammerly (1984) identified a number of factors that help maintain the treeless character of these areas: wind speed and duration; soils and geology; temperature; snow; precipitation; soil moisture; frozen ground; light intensity and biotic factors such as the lack of thermal protection from tree cover, and the lack of a seed bank for new tree establishment. Of these, the authors postulated the strongest determinants of tree exclusion to be precipitation, insolation (excessive heating) and cold.
Precipitation is the primary limiting factor for a number of species in the Columbia Basin. The height of the present Cascades Range presents a significant barrier to prevailing coastal moisture systems, leaving the east side of the mountains in a rain-shadow. The effect of the rain shadow is low precipitation and relative humidity in the Columbia Basin, with some areas receiving only 150 mm (6 inches) per year (Daubenmire, 1970). This severe aridity poses a serious constraint on species composition and growth habit within plant communities.
Taylor (1992) enumerated some of the adaptive traits which plants have evolved to survive in arid lands. Structural modifications possessed by some plants include a waxy leaf cuticle or leaf hairiness to resist solar and wind desiccation; small leaf size to reduce surface evaporation; succulence to provide water storage; moisture-obtaining structures such as modified roots; and modified anatomy to prevent dessication damage.
Many plants have modified lifestyles to grow preferentially during wet periods (Taylor, 1992). Grasses of the shrub-steppe employ a diverse range of specific strategies including tolerance of dehydration, efficient use of limited water, ability to withstand browsing, annual or ephemeral life cycles, and wind pollination. Tall sagebrush possesses both an evergreen set of leaves as well as a deciduous set which can take advantage of spring precipitation. Dense hairs on the leaves help prevent wind and solar desiccation. Sagebrush has both shallow roots to obtain water from summer thunderstorms as well as tap roots for reaching deep ground water.
The natural history of the Columbia Basin led to the development of many, diverse communities typically dominated by shrubs or grasses that are specialized for living in harsh, dry climates on a variety of soils. Many other species have adapted to these conditions, including invasive species which have fundamentally altered the function of the ecosystem, much to its and our detriment.
C. Why is it important to preserve shrub-steppe lands?
Shrub-steppe lands of the Columbia Basin once supported a nation of people. Today they help support a different nation. According to Turner et. al. (1980) Okanogan and other tribes traveled to the Columbia Basin to obtain many foods, utilitarian items and sacred materials indispensable to their cultures. Notable foods include serviceberries (Amelanchier alnifolia), bitterroot (Lewisia rediviva), camas (Camassia quamash) and Canby’s lomatium (Lomatium canbyi). Wildlife and sources of tools (such as flint and obsidian) which are unique to certain areas in the Columbia Basin were also an integral part of their cultures. Today, domestic and ritual gathering of agricultural goods still continues as a viable cultural activity amongst native people living on the Colville Indian Reservation, however many traditional hunting, fishing and root-gathering grounds have been lost or compromised so profoundly that the cultural ties to the land are in danger of being permanently lost (Wooten, 2002, Turner et. al., 1980).
The resources of the shrub-steppe now provide amenities for a new nation. The most highly productive shrub-steppe soils are those of the Palouse loess, formed from deep, fertile, wind-blown soils which cover a large expanse of southeast Washington. But because of its fertility, the Palouse shrub-steppe has been completely transformed to wheat and other agriculture (Daubenmire, 1970), and its native peoples scattered to the winds. Of all the shrub-steppe habitats and cultures that have disappeared, the Palouse affords the most profound example of loss. But from the point of view of agricultural production, the area ranks as one of the most important in the U.S. Alarmingly, estimates of soil loss from the Palouse range as high as six inches a year. In the last hundred years, all of the original topsoil has been lost from about ten percent of the cropland, and from one-fourth to three-fourths of the original topsoil has been lost from another 60 percent of the cultivated cropland (Veseth, 1985).
Many species of plants and animals are unique to and dependent upon shrub-steppe habitats. Birds like the sage thrasher, mammals like the pygmy rabbit, and a host of other sagebrush-dependent species like the sage grouse and pygmy rabbit, which were once common, are now in decline (Ritter and Paige, 2000; Christensen, 2000; Washington Department of Wildlife, 1993). In order to stem the eventual loss of these species, enough habitat needs to be set aside for natural processes to continue.
Shrub-steppe lands offer boundless opportunities for recreation. Camping opportunities exist on many different ownerships and entire towns have economies based on recreation (Johnston, 2001). The Columbia Basin is a popular locality for the recreation sector including hunters, anglers, photographers, hikers, seekers of solitude and health advocates (Babcock and Carson, 2000).
The shrub-steppe has much to tell those who will listen. There is an awakening of interest in the shrub-steppe. Educational programs have been established that focus on the Columbia Basin ecosystem (Johnston, 2001; Ritter and Paige, 2000; Haynes et. al., 1996; Quigley et. al., 1996; USDA Forest Service, 1996). In the long term, education will be an indispensable aspect of shrub-steppe conservation, both for its contributions as well as its benefits.
D. How have Washington’s shrub-steppe lands been altered historically?
The natural disturbance regime and its mode of alteration occupies a central theme in discussions of conservation prioritization. Daubenmire (1970) provided important observations of human-caused changes which have affected natural succession in the Columbia Basin, including livestock grazing, European plant invasions and fire suppression. Any plan to preserve shrub-steppe habitat must incorporate consideration for the degree of altered function which can be tolerated.
Daubenmire cited historical accounts indicating that 200,000 livestock and feral horses were present in the Washington steppe by 1855. He observed that grazing accompanied the replacement of native species with annual grasses, and that invasion by alien species was transforming the Columbia Basin on a broad scale. He attributed a large share of the invasion damage to cheatgrass (Bromus tectorum) and Kentucky bluegrass (Poa pratensis), both of which have the potential for irreversible ecosystem alteration (Mack et. al., 2000; Wooten and Morrison, 1995). But Daubenmire found no evidence to support oft-made claims that sagebrush had increased its range during the settlement period.
Also lost from overgrazed soils are the fragile crusts of mosses, lichens and fungi known as cryptogamic, or cryptobiotic, crust, which Daubenmire found to be a significant element on almost all soil types. Soil crusts perform an irreplaceable ecosystem service by maintaining soil stability, retaining moisture, transferring nutrients, and maintaining shrub dominance (Bolton et. al., 1993; Perry et. al., 1989; Anderson et. al., 1982).
Daubenmire observed that over time, the suppression of fire in the shrub-steppe results in the gradual expansion of woody species. He cited anecdotal evidence from early explorers to indicate that wildfire was not omnipresent in the shrub-steppe, but a result of controlled burning by indigenous peoples.

The impact of indigenous peoples on the Columbia Basin was significant (Turner et. al., 1980). Each spring Sanpoil tribes (a tribe now living on the present-day Colville Indian Reservation) would move to the area south the Columbia River to dig roots over a 30-40 day period, over an area covering an estimated one million acres (Ray in Turner et. al., 1980, p. 147). Native activities in the Columbia Basin involved a number of ecosystem interactions, including digging, transportation, maintaining camps and the use of burning. O.C. Stewart observed, “that all grasslands occurring on deep fertile soil are man-made, by peoples who periodically set fire to the grass and kept woody vegetation from growing …” (Daubenmire, 1970, p. 8).


The degree of degradation of shrub-steppe lands is an over-riding constraint in determining which lands deserve priority for preservation. In many cases, a misleading impression is given by figures which suggest large areas of Columbia Basin shrub-steppe remain, when in fact much of this land is so degraded as to be beyond restoration or ecological value. Part of this is due to the disparity between maps based on potential vegetation with that of the actual vegetation.
For instance, even though Quigley and Arbelbide (1997) concluded that the low sagebrush cover type is still as abundant as it was before 1900, many examples had severely altered successional pathways and the presence of invasive species. A slightly better understanding of the magnitude of loss is conveyed by the National Vegetation Classification, which lists 20% of Pacific Northwest dwarf shrub-steppe community as imperiled or critically imperiled (Anderson et. al., 1998). But it may be just as important to know what the condition is on the other 80% of dwarf shrub-steppe communitiesthroughout the arid west, much of the land is in such poor ecological condition as to render ecosystem preservation a lost cause.
In many situations, the ability to reverse deleterious changes to shrub-steppe communities may not be practically feasible. McIver and Starr (2001) summarized cases of nearly insurmountable barriers to shrub-steppe restoration. These include loss of keystone animals prerequisite for seed dispersal or pollination (Longland, 1995, Whisenant, 1995), cases where native dominants or their seed sources are lacking (Laycock, 1991; West, 1999) and cases of altered fire regime (Mack et. al., 2000). The degradation process for shrub-steppe ecosystem components proceeds through a number of successive stages which are reversible only up to a limit. Beyond this limit, the community attains such highly altered ecological processes that passive restoration efforts involving mere removal of the causative agent would be ineffective.
Thus, measures of ecosystem value need to incorporate both negative attributes such as degraded condition along with positive attributes such as diversity and rarity.
III. Study Methods
A. Study Design Considerations
It is important to consider shrub-steppe conservation regionally and over the long term. Knowledge about the location, extent and condition of shrub-steppe lands is indispensable for effective conservation prioritization, as well as for the design of conservation programs which involve land acquisition, easements, or other protective management designations.
Examples of important questions which conservation prioritization might answer include the following:


  • When is it better to save a large block of intact habitat in fair condition, over a small piece of pristine habitat?

  • When should wildlife conservation take precedence over plant community preservation? When and where are there opportunities for multi-species conservation?

  • What long-term management plans are most important for future preservation objectives?

  • How can future management adjust to unplanned changes to an area’s ecology?

  • What restoration activities are desirable in the shrub-steppe and how will they be funded?

Conservation prioritization is a crucial task which should precede larger conservation efforts, due to its ability to maximize benefits from limited funds.


Needs prioritization may be accomplished through a number of means, such as a decision hierarchy. A familiar example of a decision hierarchy is a risk analysis matrix that assigns a score for different parcels that is the product of ecosystem values and the risk of loss, based on likely land management courses. Risk assessment has a fairly large body of support (US EPA, 1998). Risk assessments are based on the assumption that some undesirable outcomes may be unavoidable, but the worst outcomes can be avoided, and the best elicited. It is possible to formulate a problem statement for land preservation as, “which parcels are the most valuable ecologically and at highest risk of loss?” The risk assessment is essentially a 2 X 2 matrix made for each parcel of land or each cell of a raster map. Each cell contains a value that is the product of the product of the value (of functional ecosystem components) times the risk (of loss). Thus high-quality habitats at great risk or endangerment would receive highest conservation priority, whereas common or degraded habitats with low threats would receive the lowest priority. Once high-priority parcels are identified for preservation, cost and practicalities can then be applied as a second set of criteria.
It is possible to assign risk scores to land parcels through knowledge of the administrative ownerships which confer protection or not on each parcel. For instance, State Natural Resource Conservation Areas would be rated low risk, National Parks as medium, and private lands in agricultural or developed areas as high.
Assigning values to shrub-steppe lands is a more intractable problem. As previously described, the assignment of value needs to incorporate both positive measures such as biodiversity and rarity as well as negative ones such as alien species presence or erosion problems. There is wide latitude for subjective error in the determination of community type and the degree of degradation. This project took advantage of existing broad habitat evaluations as a first step in making more detailed evaluations.
The remaining objectives of this study are still underway. Toward that end, two important objectives that need the most work are (1) classification of shrub-steppe vegetation with higher reliability, resolution and detail; and (2) map overlays of shrub-steppe layers onto administrative ownerships.
B. Study preparations
Arcview 3.2 with Extensions was used as the main software platform for mapping analysis. View extents were assigned to be about 325 meters larger than the furthest boundary of any input file in any direction by use of a rectangular shape file, clipcov.shp. Because the offsite bounds of some of the digital maps extended reached far west into the Pacific ocean, Analysis Properties were set to match this shapefile as follows: cell size 82.02 ft; rows: 15,538; columns: 24,013; left extent: 941,767; right extent: 2,911,335; bottom extent: 81,550; top extent: 1,355,952.
Maps used were projected in the State Plane Coordinate System, Washington State Plane South Zone, Lambert Conformal Conic, Standard Parallel 45.833333, Longitude of Central Meridian 120.5, Latitude of Projection Origin (Reference Latitude) 45.333333, Geodetic Model NAD 1927, Clarke 1866 Ellipsoid. Planar distance units were in feet and cell size was 25 m (82.02 feet), except for the NHI-Historical map which was converted from a cell size of 1 km to one of 25m
A number of different sources for digital shrub-steppe maps were examined, and three of these were used for base maps in this study. These were: (1) GAP analysis maps for Washington, Version 5 digital land cover maps (Cassidy, 1997; also referred to here as “lcv5” coverages); maps of shrub-steppe made by cooperatively by National Habitat Institute (NHI) and Washington Department of Fish and Wildlife (Kiilsgard , 1999, Kiilsgard and Barrett, 1999a and 1999b) and provided online by NHI as (2) NHI-Current and (3) NHI-Historical (presettlement, ca. 1850) maps.
The NHI and GAP maps were produced with different classification methods. The GAP map polygons were vector files made through photo-interpretation of major land cover and land use data within visually homogenous polygons derived from 1991 Thematic Mapper data, with a nominal minimum mapping unit of 100 hectares.
The NHI map are raster grid data derived from a rule-based classification scheme based on spectral and topographic attributes of the pixels. Nine Landsat Thematic Mapper scenes were used to classify cells of the NHI maps at a map scale of 1:100,000. All imagery contained less than 10% cloud cover and was acquired from May to October 1996.
NHI maps (as downloaded from the internet) are classified into 33 broad plant associations and landforms from an unsupervised maximum likelihood classifier algorithm, followed by vegetative typing and condition classfication using successive field verification in combination with ancillary data (such as topography) to refine the classification. Collateral data used included:


  • National Wetlands Inventory for westside, montane, and eastside riparian habitats.

  • WDFW’s Blue Mountains habitat/vegetation mapping project directed by Brian Cosentino.

  • WDFW’s Shrub steppe vegetation mapping of eastern Washington, directed by John Jacobson.

  • WDNR-Heritage Program mapping project for west side grasslands and west side oak and dry Douglas fir forests for lands west of the Cascade crest.

  • US National Park Service for montane vegetation in Mount Ranier, North Cascades, and Olympic National Parks.

  • US Biological Service- Gap Analysis Program state of Washington vegetation map.

Analysis of the NHI-current maps was made using grid files containing classes for Eastside Interior Canyon Shrublands Type 14; Eastside Interior Grasslands Type 15; and Shrub-steppe Type 16, while excluding counts of cells representing offsite (00) and Canada (45). For comparison with GAP potential vegetation maps, a second version of the NHI-Current shrub-steppe map was made which is comprised of only those cells that overlap the GAP potential shrub-steppe vegetation grid, ssgap5. This grid file was named ssnhigap.


The analysis of the GAP land cover version 5 (“lcv5”) maps was developed using two data fields. The field “Zonet”, contains vegetation attribute codes given below; the field “Prim” is a mutually exclusive classification of major land cover types including ones used in this project: bare, developed, agricultural, water and wetland.
The Zonet classes used for shrub-steppe analysis were:

*2 Pinus ponderosa / steppe and Quercus garryi / steppe openings (Forest / steppe)

11 Festuca idahoensis/Rosa nutkana (Blue Mountains Steppe FEID/RONU)

12 Festuca idahoensis/Symphoricarpos albus (Palouse FEID/SYAL)

13 Artemisia tripartita/Festuca idahoensis (Three-tip Sage A. trip./FEID

14 Festuca idahoensis/Hieracium cynoglossoides (Klickitat Meadow Steppe FEID/Hier. cyno.)

15 Purshia tridentata/Festuca idahoensis (Bitterbrush PUTR/FEID)

16 Artemisia tridentata/Agropyron spicatum (Central Arid Steppe ARTR/AGSP)

17 Agropyron spicatum/Festuca idahoensis (Wheatgrass/Fescue AGSP/FEID)

18 Agropyron spicatum/Poa sandbergii (Canyon Grasslands AGSP/POSE)

19 Artemisia tridentata/Festuca idahoensis (Big Sage/Fescue ARTR/FEID)
* Class 2 was developed for this project by combining GAP ponderosa pine and oak forests with NHI-Current shrub-steppe cells.
Procedures
More details about the analysis procedures are included in Appendix B.
The potential (historic) vegetation map was developed from combining GAP shrub-steppe, herbaceous and meadow classes 11, 12, 13, 14, 15, 16, 17, 18, and 19. This layer was modified by addition of class 2, Shrub-steppe openings in ponderosa pine and oak forests. The added layer, Shrub-steppe forest openings, was made by intersecting the ponderosa pine and oak layers from the GAP maps with NHI shrub-steppe cells. This layer was then mosaiced back into the GAP shrub-steppe map, after processing to clean up small groups of cells with the Grid Enhancement extension Gridtools.avx (Schäuble, 1988). The cleaning involved a 1-cell shrink, followed by a 1-cell, 2-pass Boundary Clean with priority given to zones of larger area. This increased the area of shrub-steppe lands on the GAP coverage by 4,033,436 cells or 973 sq mi. The resultant potential vegetation map was named ssgap5.
A map layer of non-shrub-steppe cells was made by querying the GAP field Prim to create individual grids for developed, agricultural, deep water and wetlands. These grids were combined into a single theme and then clipped to match the extent of cells of the potential vegetation map ssgap5.
The determination the extent of shrub-steppe regional habitat types was performed by merging the grid nonss with ssgap5 and exporting the attribute values into a Microsoft Excel spreadsheet for calculations of area.
The determination of the extent of shrub-steppe overlap on major agency land owners in Washington was made using WSDOT (1995) coverages of Indian Reservations, Military sites, National Recreation Areas and National Forests. The files were first processed by reprojection. Next features of the agency coverage that intersected the selected shrub-steppe polygons were selected and with the selected themes active, the Arcview Summarize Zones command was used to determine the overlap of those polyons with the grid cells in the shrub-steppe grid ssgap5. Results were exported to a Microsoft Excel spreadsheet with the following results (data is rounded to the nearest mile unless it is less than one square mile or zero).
IV. Results

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