Proposal for Establishing a Demonstration Site for Pinyon-Juniper Restoration

Transcription

1 Proposal for Establishing a Demonstration Site for Pinyon-Juniper Restoration Prepared by: David Huffman Pete Fulé W. Wallace Covington Doc Smith Ecological Restoration Institute Northern Arizona University Flagstaff, AZ Tel (928) Fax (928) David.Huffman@nau.edu January 3, 2002

2 Introduction Pinyon-juniper woodlands are estimated to cover approximately 22.5 million hectares in the western United States. Around 40% of this area occurs in Arizona and New Mexico (Powell et al. 1994). Just over 10% of pinyon-juniper lands in these states are administered by the Bureau of Land Management (BLM) (970,000 ha); US Forest Service (USFS) administers about 35% (3,198,400 ha), other federal agencies are responsible for around 25% and the remainder is on nonfederal lands (Powell et al. 1994). Disturbance patterns and vegetative communities vary considerably across the range of the cover type depending upon site characteristics (e.g., soils, topography) and geographic location. For example, in northwestern Arizona, pinyon-juniper woodlands are often dominated by Pinus edulis, P. monophylla, and up to four species of Juniperus whereas Pinus cembroides and one-seeded junipers commonly dominate sites in southeastern Arizona (Brown 1994). Similarly, understory woody and herbaceous species can occur in a broad array of associations. As found for other western forest types, ecological degradation associated with intensive livestock grazing, fire exclusion, and other land uses is common in pinyon-juniper woodlands (Covington et al. 1994). Increases in overstory density, thought to be in part driven by livestock grazing and fire exclusion, has led to decreases in abundance and richness of understory species, depletion of soil seed banks, and severe topsoil erosion (Tausch et al. 1981, Jacobs and Gatewood 1999). In many pinyon-juniper woodlands, fuel buildups have shifted natural disturbance regimes from low intensity to high intensity fires that lead to increased site degradation in terms of further soil loss, exotic species invasion, and type conversion (Gruell 1999, Jacobs and Gatewood 1999, Goodrich and Rooks 1999). Ecological degradation of these systems represents not only a loss of habitat for naturally occurring woodland species but also a diminishment of natural resource options for both current and future human generations. On these sites, ecological restoration treatments are warranted in order to halt degradation processes and reestablish woodland structure and ecological function more consistent with conditions that prevailed prior to intensive land management practices and fire regime disruption. This proposal is for an ecological restoration demonstration project to be conducted on a BLM administered pinyon-juniper site on the Arizona Strip District near Mount Trumbull. The project will test technical frameworks previously established for restoration of ponderosa pine ecosystems in terms of determining site reference conditions, retention and replacement of presettlement-aged tree structures, mechanical thinning of post-settlement trees, and application of prescribed fire for fuel management and ecological process objectives. Seeding with native understory plants and exclusion of livestock grazing will likely be necessary across much of the area. The purposes of the demonstration are the following: (1) to gather preliminary information concerning application of pinyon-juniper restoration treatments; (2) to establish protocols for long-term monitoring of pinyon-juniper restoration projects; (3) to increase our understanding of the responses of species, communities, and processes in pinyon-juniper woodlands to restoration treatments such as overstory thinning, prescribed 2

3 fire and seeding; (4) to provide a preliminary evaluation of costs and benefits of pinyonjuniper restoration to human systems; (5) to increase public awareness of ecological restoration needs in pinyon-juniper woodlands; (6) to create a site where interested groups could visually assess structural and functional differences between degraded and restored woodlands. In addition, the information gained in this project may be additionally used to compare with companion pinyon-juniper and ponderosa pine restoration experiments conducted on other sites in the Southwest. Site Selection Methods Representatives from the Ecological Restoration Institute (ERI) and the BLM will meet at the Mt. Trumbull research facility in early summer 2001 to explore possibilities for the demonstration project site. In a meeting at Northern Arizona University on December 4, 2001, two possible sites were mentioned by BLM staff. It was agreed that the site should broadly represent environmental conditions of local pinyon-juniper woodlands. Nine to twelve mature- or old-growth-class (see Field Measurements) pinyon and juniper trees or tree evidences per hectare (4 5 trees per acre) should be present to indicate presettlement woodland occupancy of the site. Although this project will demonstrate ecological restoration in pinyon-juniper ecosystems, extremely disturbed sites, as indicated by deeply cut arroyos or infestations of exotic plant species will not be considered. The site should comprise at least 9 hectares (22.2 acres) in order to establish one treatment (demonstration) unit and one control unit of at least 4.5 hectares (11.1 acres) each. A larger site that could accommodate an expanded project in the future is desirable. Specific size and location of the treatment will be further discussed among ERI and BLM staff. After site selection, the two units (demonstration and control) should be demarcated using standard boundary marking procedures. Square corners and straight boundaries should be avoided although the area should follow existing roads, drainages, or type lines to facilitate treatment and fire control. If logistically feasible, the treatment unit will be randomly selected from the pair. Field Measurements Methods for the establishment and measurement of permanent monitoring plots will follow procedures currently in use by ERI on other ecological restoration projects (see Waltz et al. 2001) with certain modifications. These procedures will be used for pretreatment and post-treatment sampling. Additional measurements including crown scorch and charring on pinyon and juniper trees as well as fire severity measurements will be added for post-burn sampling. Six 0.04-ha plots (0.1 acre) will be established on a 60-m (196.8 ft) grid in each unit. Plot centers will be established with steel rebar and geo-referenced for long-term 3

4 monitoring. On these plots, overstory, understory, and fuels data will be recorded in order to describe pretreatment structure, composition, and response to restoration treatments. Additionally, photopoints will be established to document visual changes. All live trees greater than breast height (1.37 m (4.5 ft)) on plots will be tallied by species and measured for total height. Pinyon and juniper stems will be measured for diameter at stump height (DSH at 40 cm (15.7 in)) and tagged for remeasurement. Trees will be classified in the field using four maturity classes based on DSH, height, bark characteristics, and crown form (Bradshaw and Reveal 1943, Blackburn and Tueller 1970). Trees in maturity classes 3 and 4 ( mature and old-growth, respectively) will be presumed to be near presettlement in age ( 130 years) (Blackburn and Tueller 1970, Barger and Ffolliott 1972). Trees in maturity classes 1 and 2 ( seedling and sapling respectively) will be presumed to be post settlement in age (<130 years). For all trees in classes 3 and 4, crown radius will be recorded by taking the average of two perpendicular measurements. Increment cores taken at DSH will be collected for all class 3 and 4 trees. Additionally, crown radius will be measured and increment cores collected from a 20% random subsample trees in classes 1 and 2. Due to difficulties in crossdating juniper species and variability in annual ring production (J. Bailey pers. comm.), two increment cores, taken at perpendicular angles, will be collected for each juniper tree. Dead tree structures (i.e., snags, logs, stumps) will be tallied by condition class as described by Thomas et al. (1979) and Maser et al. (1979) for ponderosa pine and measured for DSH. Understory transects (50 m (164 ft)) oriented parallel to the plot slope and centered on plot centers (i.e., 25 m (82 ft) above and below plot centers) will be established at each plot. Transect endpoints will be established with steel rebar for long-term monitoring. Along transects on alternating sides, 1-m square plots will be placed at 5-meter (16.4 ft) intervals (10 plots per transect). On each of these small plots, cover of herbaceous (nonwoody) plant species will be recorded. Transects will also be used as centerlines for 10- m (32.8 ft) wide sampling belts. On belt transects, a species list of all plants will be recorded and woody plants will be tallied by life stage and species (e.g., seedling, sprout, mature). Tree seedlings (< 1.37 m (4.5 ft)) will be tallied on a 100-m 2 (0.025 ac) plot nested within the larger overstory plot. Dead woody fuels will be tallied and forest floor depth measured on m (50 feet) transects established in a random direction from plot centers. Two photopoints per plot will be established at north and east points on the overstory plot perimeter. Photographs will be taken toward plot center with the horizon located in the lower 1/3 of the field of view. Dry-erase boards will be used to document plot number and date of the photos. Treatments Treatments applied to the demonstration unit will include thinning of pinyon and juniper trees in maturity classes 1 and 2, prescribed burning to reduce woody fuels, and seeding with native plant species. The thinning treatment will follow a 1:3 presettlement evidence replacement prescription outlined for other ERI restoration projects with certain 4

5 modifications (Covington et al. 1997, Fulé et al. 2001). All live pinyon and juniper trees of maturity classes 3 and 4 will be retained in the post-treatment unit. Additionally, presettlement evidence (snags, logs, stumps 20 cm (7.87 in) DSH) will be replaced with post-settlement-aged trees at a rate of 3 trees per evidence. When presettlement tree evidence is found, a search for post-settlement replacements will be conducted within a radius of 3 m (9.84 ft) (presumably a typical crown radius of mature pinyon or juniper tree). If suitable replacement trees are not found within this radius, it will be expanded to 6 m (19.68 ft). Pinyon and juniper trees to be retained will be marked and all others will be removed by mechanical thinning. In this demonstration, only pinyon and juniper species will be cut. Methods of thinning and machinery access to the site will be discussed further among ERI and BLM staff. Large ( 10 cm diameter) woody fuels generated by thinning will be piled and burned on site or sold as fuel wood. This will be discussed further among ERI and BLM staff. Finer fuels will be scattered to promote plant establishment and reduce erosion. Timing of broadcast burning will be determined by understory community development and composition following thinning. Construction of firelines or use of existing fuel breaks will be necessary to conduct broadcast burning. Responsibilities for this work will be further discussed among ERI and BLM staff. When broadcast burning is conducted fire behavior and weather data will be collected. Native plant seeds should be broadcast after thinning and pile burning treatments have been completed. This however may not be logistically feasible. Regardless, seeding should coincide with onset of summer rains. Seeding rate and species mix will be determined by availability of resources and costs. These details will be further discussed among ERI and BLM staff. Although seed predation is thought to be a serious concern for restoration of pinyon-juniper woodlands, rodent control is not likely feasible for this demonstration. However, fencing of the study area and/or restriction of cattle grazing will be necessary throughout the demonstration period. This demonstration provides opportunity for researchers outside of the ERI to establish studies. Timing and application of treatments should be coordinated with any other interested parties. Data Analyses Due to the exploratory nature of this project and the limitations of the experimental design, data analyses will be mainly descriptive. Data summaries for pretreatment conditions will include overstory and understory structure and composition and fuel loadings. Paired t-tests will be used to compare structural and compositional parameters between treatment and control units. For count data and those that do not adhere to assumptions for classical tests, nonparametric analyses may be used. Post-treatment changes will be summarized and comparisons made following procedures for pretreatment data. Results of these analyses and observations made during the restoration process will be used to develop future pinyon-juniper woodland restoration experiments at larger scales. 5

6 Schedule Outlined below is a tentative schedule for sampling and treatment of the demonstration site. Activity Responsibility Date Site selection and unit layout ERI and BLM staff June-July 2002 Pretreatment sampling ERI field staff July-August 2002 Marking and thinning BLM staff, ERI assistance September-December 2002 Seeding BLM staff and/or ERI field staff July-August 2003 Pile burning BLM staff, ERI monitoring September-November 2003 Post-thinning sampling ERI field staff September 2003 Broadcast burning BLM, ERI monitoring TBA Post-treatment (full) sampling ERI field staff TBA Literature Cited Blackburn, W. H., and P. T. Tueller Pinyon and juniper invasion in black sagebrush communities in east-central Nevada. Ecology 51: Bradshaw, K. E., and J. L. Reveal Tree classifications for Pinus monophylla and Juniperus utahensis. Journal of Forestry 41: Brown, D. E. (ed.) Biotic communities southwestern United States and northwestern Mexico. University of Utah Press, Salt Lake City, UT. 342 p. Covington, W.W., P.Z. Fulé, M.M. Moore, S.C. Hart, T.E. Kolb, J.N. Mast, S.S. Sackett, and M.R. Wagner Restoration of ecosystem health in southwestern ponderosa pine forests. Journal of Forestry 95(4): Covington, W. W., R. L. Everett, R. W. Steele, L. I. Irwin, T. A. Daer, and A. N. D. Auclair Historical and anticipated changes in forest ecosystems of the Inland west of the United States. Journal of Sustainable Forestry 2: Fulé, P. Z., A. E. M. Waltz, W. Wallace Covington, and T. A. Heinlein Measuring forest restoration effectiveness in reducing hazardous fuels. Journal of Forestry 99: Goodrich, S., and D. Rooks Control of weeds at a pinyon-juniper site by seeding grasses. In: Monsen, S. B. and R. Stevens (comps.). Proceedings: ecology and management of pinyon-juniper communities within the Interior West USDA Forest Service Proc. RMRS-P-9, Rocky Mountain Research Station, Ogden, UT. Gruell, G. E Historical and modern roles of fire in pinyon-juniper. In: Monsen, S. B. and R. Stevens (comps.). Proceedings: ecology and management of pinyonjuniper communities within the Interior West USDA Forest Service Proc. RMRS-P-9, Rocky Mountain Research Station, Ogden, UT. Jacobs, B. F., and R. G. Gatewood Restoration studies in degraded pinyonjuniper woodlands of north-central New Mexico. In: Monsen, S. B. and R. Stevens (comps.). Proceedings: ecology and management of pinyon-juniper 6

7 communities within the Interior West USDA Forest Service Proc. RMRS- P-9, Rocky Mountain Research Station, Ogden, UT. Maser, C., R. G. Anderson, K. Cromack, Jr., J. T. Williams, and R. E. Martin Dead and down woody material. pp In Wildlife habitats in managed forests -- the Blue Mountains of Oregon and Washington. USDA Agricultural Handbook 553, Washington, D.C. Powell, D. S., J. L. Faulkner, D. R. Darr, Z. Zhu, and D. W. MacCleery Forest resources of the United States, USDA Forest Service General Technical Report RM-234, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO. Tausch, R. J., N. E. West, and A. A. Nabi Tree age and dominance patterns in Great Basin pinyon-juniper woodlands. Journal of Range Management 34: Thomas, J.W., R.G. Anderson, C. Maser, and E.L. Bull Snags. Pages in Wildlife habitats in managed forests--the Blue Mountains of Oregon and Washington. USDA Agricultural Handbook 553, Washington, D.C. Waltz, A., P. Fulé, and J. Springer Mt. Trumbull Experimental Blocks: One year following treatment. Ecological Restoration Institute Report, Northern Arizona University, Flagstaff, AZ. 7