TOPIC 5 RESTORATION OF SAGEBRUSH ECOSYSTEMS: SCIENCE

Prioritizing Landscapes/Locations for Restoration

The combination of management zones, Priority Areas for Conservation (PACs), and landscape cover of sagebrush provide an initial means to identify and prioritize areas for restoration and management strategies.

Prioritizing landscapes/locations for restoration should use:

Priority Areas for Conservation (PACs)

Sage-grouse populations will benefit more from restored habitat inside PACs (cross-hatched areas in the graphic) than from restored habitat within the current sage-grouse range, but outside PACs (uniform gray areas in the graphic). Restoration efforts that take place in either of these designated landscapes (within PACs or within the current range) will benefit sage-grouse more relative to restoring areas outside the current range (Pyke et al. 2015b, Figure 1).

Figure 1: Click on map for a printable PDF version.

Areas of Highest Breeding Sage-grouse Density

Areas of highest grouse density can be priorities, versus those with lower densities, since sage-grouse have a very highly clustered distribution. For an example, see Doherty et al. (2016), Figure 10.

Figure 10: Click on map for a printable PDF version.

Resistance & Resilience

Resilience to disturbance increases with cooler soil temperature and with wetter soil moisture regimes. Revegetation successes also tend to increase along similar gradients. This figure from Chambers et al.(2017), Figure 6, shows how these gradients are spatially explicit and can be mapped. Areas with high or low temperature and moisture regimes can be compared and the corresponding likelihood of restoration success predicted.

Figure 6: Click on map for a printable PDF version.

Landscape Cover of Sagebrush

Landscape cover also includes native perennial grasses and forbs, but sagebrush is easily detected with remote sensing equipment and provides a surrogate for the community as a whole. Most importantly, sage-grouse population lek persistence is related to sagebrush landscape cover. For example, this map (Pyke et al. 2015b, Figure 5) shows variation in sagebrush cover across the range.

Figure 5: Click on map for a printable PDF version.

Human Disturbance

Human disturbance is strongly negatively associated with sage-grouse occurrence and persistence (see Knick et al. 2013 and the Conservation Issues Lesson).

Avoidance of anthropogenic stressors (habitat fragmentation, pollution, introduction of exotic species, croplands, Interstate highways and roads, energy development [wells, wind towers], mining sites, communication towers and transmission corridors, urban development) should be factored into selecting restoration sites in order to increase the probability of success.

To appropriately avoid human disturbance, it is recommended that disturbance buffer distances, such as those defined in Manier et al. (2014), Table 1, be incorporated in locating restoration sites.

Breeding Habitat Probability Matrix

Many of these factors can be combined into the sage-grouse habitat resistance and resilience matrix, which combines sagebrush cover of landscape and resilience to disturbance/resistance to invasive annual grasses (Chambers et al. 2016, Table 8). See the lesson on Resistance & Resilience for more detail on this table.

Open the graphic to view information about this matrix.

Breeding Habitat Matrix

The rows represent the generalized plant communities among the ecological types with communities ranging from cold and moist (high resilience and resistance, blue row) to warm and dry (low resilience and resistance, red row).
The columns show the current proportion of the landscape dominated by sagebrush, ranging from low (< 25% sagebrush cover) to high (> 65% sagebrush cover) probability of sage-grouse breeding.
The rows in the matrix represent the probability of restoration or recovery which is associated closely with soil temperature and moisture regimes (Chambers et al. 2017).
The general management goal in a landscape or site is to move toward the right within a row; there is no movement between rows within a landscape or site.

Table 8

Restoration Effectiveness

There are a variety of restoration techniques which can be used for effective restoration of sagebrush. First, click Play to listen to Tony Svejcar discuss ineffective legacy restoration technologies.

Effective restoration techniques include:

Reseeding

Techniques for seeding sagebrush, such as drill seeding, aerial broadcast, surface broadcast, seed dribbler, or any type of seeding that allows seed to remain at the soil surface, require soil disturbance or compaction (for example, harrowing, chaining, seeding followed by cultipacker) to provide good soil-to-seed contact (Pyke et al. 2015a). Harrowing or chaining breaks up the soil surface and allows the seed to fall in locations where slight soil sloughing will occur, or seeding on the surface followed by a cultipacker or other equipment that can press seeds into the soil surface, are reported to work best (McArthur and Stevens 2004). Seeds buried too deeply either germinate and die before reaching the surface or may become dormant until they reach light to stimulate germination (Wijayratne and Pyke 2012). This implies that aerial seeding without these additional measures may lead to failure on wildfire rehabilitation treatment areas, but mixed results have been found from several studies (Knutson et al. 2014) and the additional treatment increases the overall cost.

Transplanting

Transplanting sagebrush is a method to consider in conjunction with reseeding (Pyke et al. 2015a). Transplants of sagebrush tend to have higher degrees of success relative to seeding provided that basic procedures are followed in conducting the transplanting. It may not be cost effective to transplant an entire restoration site to achieve full sagebrush occupancy, but it may be possible to establish scattered islands of sagebrush throughout a project or widely spaced shrubs to form seed sources for additional spread of sagebrush during future favorable conditions at nearly equal costs but with greater potential for successful establishment (Knutson et al. 2014). Although this might be a slow process, it closely mimics natural dispersal after fires, where small patches of shrubs would become the parent plants for future establishment and spread.

Reseeding or Transplanting?

When should you use reseeding or transplanting techniques? Click Play to listen to Jay Kerby discuss seeding and plugs.

As mentioned earlier, perennial grasses (or bunchgrasses) are the most important life form for achieving at least partial restoration success of sagebrush steppe ecosystems (Pyke et al. 2015a). In general, this group of species is more successful as elevation and precipitation increase and soils become cooler and moister throughout the region (Knutson et al. 2014). Using a seed drill to plant seeds aids establishment and allows for more success in warm and dry environments (Hardegree et al. 2011, Knutson et al. 2014), but many cool and moist sites may be capable of unassisted recovery.

Click Play to listen to Tony Svejcar discuss the benefits of bunchgrass.

Because seed size may vary among species, seeding depth is commonly an important factor relating to seeding success (Hardegree et al. 2011). Recommended seeding depths by species are reported in Monsen and Stevens (2004). Depth bands are commonly applied to drills to insure the appropriate seeding depth is achieved and should be used as a best management practice when seeding species in sagebrush steppe ecosystems. They are also used to minimize soil disturbance to create minimum till drills. Multiple seed boxes that feed seeds of different sizes or with appendages (for example, awns and plumes) into different seed tubes on drills may be necessary to seed species that require different depths or further mixing to pass through seeding tubes. Forbs are important for sage-grouse brood rearing and should be included when possible on restoration projects when they are known to be missing from the ecosystem.

Quantifying Restoration Effectiveness

To better understand how and where to restore degraded sagebrush landscapes, Arkle et al. (2014) measured Greater Sage-Grouse occupancy at survey sites across the Great Basin to compare sites that were burned by wildfire, but untreated with any restoration technique; burned and seeded; and unburned and untreated. They found the following relationships:

Sage-grouse occupancy was positively related to plot- and landscape-level dwarf and big sagebrush steppe prevalence, and negatively associated with non-native plants and human development.
Based on plot-level vegetation characteristics alone (i.e., not accounting for the surrounding landscape, connectivity, or proximity to extant populations), sage-grouse were relatively unlikely to use many burned areas of the Great Basin for at least 20 years, regardless of whether post-fire seeding treatments were implemented.
On average, aerial seeded and drill seeded areas were no more likely to support sage-grouse occupancy than burned-untreated areas, indicating that seeding techniques or seed sources used during this time period were generally ineffective at improving post-fire habitat conditions for sage-grouse within two decades.
Plots with high predicted probabilities of sage-grouse occupancy tend to occur in areas with lower annual temperatures (primarily cooler spring and fall temperatures), greater April–June precipitation (less reliance on summer monsoonal precipitation), greater total precipitation, higher elevation, higher plant species richness, lower cattle use, and at Emergency Stabilization and Rehabilitation (ESR) projects, conducted in years with greater post-seeding precipitation.
A high quality plot embedded in a low quality landscape is still unlikely to be occupied by sage-grouse. Therefore, land managers may want to evaluate the probability of restoration success at a given site and the quality of the surrounding landscape, potentially focusing restoration dollars on relatively intact landscapes or implementing a triage-type strategy.
From a sage-grouse habitat perspective, even the most initially successful post-fire restoration projects in the Great Basin should be viewed as the initial phase of long-term investments rather than as short-term mitigation aimed at preserving particular sage-grouse populations because restoring high quality sage-grouse habitat may require a time span equivalent to several sage-grouse generations.
With respect to sage-grouse habitat, our ability to ‘‘fix what’s broken’’ after large wildfires is currently limited in Wyoming big sagebrush habitats of the Great Basin.
Improvements to ESR approaches (i.e., increasing sagebrush and native herb establishment when possible, reducing invasive plant dominance) and prioritization of sage-grouse specific follow-up restoration funding for particular landscapes may be necessary to maximize conservation effectiveness.
Given current fire frequencies and rehabilitation and restoration capabilities, protection of landscapes containing a mix of dwarf sagebrush and big sagebrush steppe, minimal human development, and low invasive plant species cover may provide the best opportunity for conservation of sage-grouse habitats.

Invasive Grass Re-Establishment

Invasive species are addressed more fully in topic 4 (Systems Invaded by Annual Grasses); however, cheatgrass, medusahead, and North Africa grass re-establishment remains an ongoing challenge to restoration efforts. Monaco et al. (2016) conducted a meta-analysis of various treatment methods used to discourage cheatgrass (Bromus tectorum) re-establishment from seed banks.

The results from the meta-analysis are illustrated in the graph (Monaco et al. 2016, Figure 12.3). Specifically:

Burning reduced percentage cover of B. tectorum in the early phases of studies, yet after a few years, this effect was not significant (first row of the top graph).
Burning clearly increased biomass production of B. tectorum on a per area basis in both the short and long term (first row of the bottom graph). Recent research illustrates that a very short time period exists after wildfire when conditions are favorable for the establishment of perennial species.

Figure 12.3

Defoliation by grazing or mowing reduced B. tectorum biomass for up to 2 years (second row of the bottom graph) and percentage cover for only 1 year (second row of the top graph). Defoliation treatments need to be applied for more than 2 years because B. tectorum can regrow following defoliation under favorable environmental conditions. The prudent use of defoliation and/or grazing in mixed herbaceous stands should include the application of time-controlled, short- duration, or high-intensity strategies to selectively graze annual grasses when they are most palatable and when perennial grasses are dormant and grazing tolerant. It may be more effective to plan and implement defoliation treatments in drier years to maximize the effect on seed production while minimizing regrowth potential—particularly in areas where defoliation will not be detrimental to residual native species.
Herbicide application consistently reduced both short- and longer-term B. tectorum percentage cover and biomass (third row of top and bottom graphs).
Revegetation (seeding desirable perennial plant species after wildfires, prescribed burning, or burning in concert with herbicide treatments) reduced B. tectorum biomass production (fourth row of the bottom graph), but its effect on B. tectorum cover was variable, especially in the long term (fourth row of the top graph).

Topic 5 Restoration of Sagebrush Ecosystems:
Science