Long-Term Vegetation Transects – Monitoring Recovery on the T-17 Fire Plots (2013)
Investigators and Affiliations
- Amy D. Forman, Plant Ecologist, Environmental Surveillance, Education, and Research Program, Gonzales-Stoller Surveillance, Idaho Falls, I
- Jackie R. Hafla, Natural Resource Specialist, Environmental Surveillance, Education, and Research Program, Gonzales-Stoller Surveillance, Idaho Falls, ID
- Roger D. Blew, Ecologist, Environmental Surveillance, Education, and Research Program, Gonzales-Stoller Surveillance, Idaho Falls, ID.
- U.S. Department of Energy, Idaho Operations Office
During the summer of 2011, LTV data were collected across all active LTV plots and data collection was completed in the first week of August. On August 25, the T-17 Fire burned 11 LTV plots along T-17 (Figure 1), providing a unique opportunity to monitor fire recovery on a number of plots which were recently sampled and had been well-characterized for decades prior to the fire. A few previous fire recovery studies have been conducted on the INL Site over the past twenty years and their results have been useful for understanding general post-fire vegetation dynamics.
Fire ecology studies on the INL Site and from other southeast Idaho locations suggest that a plant community reestablishing after a fire will be a reflection of the community present before the fire, with the exception of big sagebrush (Artemisia tridentata; Ratzlaff and Anderson 1995, Buckwalter 2002, Blew and Forman 2010). Typically, native plant communities in good pre-burn ecological condition will return to diverse, native plant communities within a few growing seasons post-burn and can resist invasion and/or dominance by non-native species. Recommendations for management of burned areas on the INL Site were based on the results of these studies and lead to the following guidance (Blew and Forman 2010):
- Vegetation management strategies should focus on enhancing the vigor of native, herbaceous species, regardless of burn status, because areas with vigorous native perennial plant communities are at less risk for post-fire invasions and are less likely to require active restoration to establish a healthy plant community following a fire.
- Managing for vigor of perennial grasses should be the highest vegetation management priority on recently burned areas, because sagebrush and other shrubs that increase habitat value are more likely to establish on good condition sites than on sites with an abundance of non-natives.
- A healthy pre-fire plant community can increase the resilience of a site, allowing substantial post-fire recovery, even under very adverse conditions like severe drought.
While these guidelines provide a solid overarching philosophy for long-term post-fire vegetation management, they offer little direction for specific scenarios which necessitate enhancing shrub recovery in the short term or identifying specific events or conditions which may shift the recovery trajectory of a plant community to a less desirable state. The studies on which post-fire guidelines are based were conducted entirely post-fire, and pre-burn conditions were extrapolated from general conditions reported for plant communities elsewhere on the INL Site. Monitoring post-fire vegetation composition and comparing it to pre-fire vegetation dynamics will yield information important for characterizing a specific burned site and evaluating its potential to return to a desirable state. This information will in turn be useful for prioritizing restoration efforts by quantifying how the range of variability for recovering communities compares to range of variability in pre-burn communities. This information can be used to address issues like determining the abundance at which cheatgrass shifts from being a minor, somewhat ephemeral component of a plant community to a truly invasive community dominant. Understanding not only the current condition of a site, but its status in terms of its potential historical range of variability can be a powerful tool for determining the need for active restoration.
The primary objective of this post-fire monitoring effort is to follow short-term vegetation recovery patterns on the 11 plots burned in the 2011 T-17 Fire and to assess the extent to which post-fire plant communities recover. Specifically, we are interested in how quickly community dynamics reflect pre-burn range of variability and to what extent other factors like weather and non-native species influence vegetation recovery. We also hope to gain information useful for developing more specific guidelines for post-fire assessments of potential recovery to support conservation planning on the INL Site. Specific issues affecting post-fire recovery which can necessitate active restoration and can be monitored using this data set include; risk of post-fire cheatgrass dominance based on pre-fire abundance, effects of precipitation patterns on various native and non-native functional groups pre-and post-burn, and length of time fire induced vegetation compositional changes (other than loss of sagebrush) may persist.
Accomplishments through 2013:
All active LTV plots were sampled for the 12th time during the summer of 2011 using the same standard techniques that have been used for estimating cover and density throughout the history of the LTV project. See Forman et al. (2010) for detailed sampling methodology. In 2012 and 2013, we sampled the 11 LTV plots that burned in the T-17 Fire during the same time frame (late-June to mid-July), within about one week of when they were sampled in 2011. Initial results comparing the plant community composition of each plot immediately prior to the fire to the composition of each plot almost one year after the fire are included in the most recent comprehensive LTV report (Forman et al. 2013). Data from 2013, the second post-fire growing season, and beyond, will be analyzed with the next full LTV effort.
Initial results from data collected in 2011 and 2012 confirm that shrub and perennial forb cover are significantly reduced one year post-fire. However, cover from native, perennial graminoids was not significantly different post-fire than it was pre-fire (Table 1). This result indicates established perennial grasses readily resprout post-fire and it is particularly impressive given that total precipitation in spring and early summer of 2012 were far below average. Introduced annual and biennial cover, mostly from cheatgrass, was significantly lower post-fire than it was pre-fire (Table 1). This pattern has been noted in other post-fire data sets from the INL Site (Rew et al. 2012, Forman et al. 2013), but it is unclear whether reductions in abundance are from effects of the fire or are related to precipitation patterns that happen to coincide with post-fire recovery. It is also unknown whether post-fire reductions in cheatgrass are temporary and limited to a few seasons post-fire, or whether they persist and change the trajectory of a plant community long-term. See Forman et al. 2013 for more detailed results from comparison of the 2011 and 2012 data.
Plans for Continuation:
Monitoring these 11 plots annually for the 5 years between comprehensive LTV sampling periods (2011 and 2016) will provide important and useful insight on the recovery of native species and on the redistribution and spread of introduced species following fire. Short-term annual data collection will also allow us to characterize the relative importance of precipitation on recovery, especially under more moderate conditions than occurred in 2012. Comparing recovery data over a five year period to historical vegetation dynamics should provide enough information to begin developing a basis for prioritizing restoration activities in burned areas elsewhere on the INL Site using short-term post-fire vegetation data. A comprehensive data analysis from monitoring the 11 LTV plots located in the T-17 burned area for five years post-fire will be included in the next LTV report, following complete LTV sampling in 2016.
Publications, Theses, Reports:
Results summarizing data collected in 2011 and 2012 can be found in:
- Blew, R. D., and A. D. Forman. 2010 Tin Cup fire recovery report. STOLLER-ESER-143, Environmental Surveillance, Education, and Research Program, Idaho Falls, ID.
- Buckwalter, S. P. 2002. Postfire vegetation dynamics in sagebrush steppe on the eastern Snake River Plain, Idaho. Idaho State University, Pocatello.
- Forman, A. D., J. R. Hafla, and R. D. Blew. 2013. The Idaho National Laboratory Site Long-Term Vegetation Transects: Understanding Change in Sagebrush Steppe. Environmental Surveillance, Education, and Research Program, Gonzales-Stoller Surveillance, LLC, Idaho Falls, ID. GSS-ESER-163.
- Ratzlaff, T. D., and J. E. Anderson. 1995. Vegetal recovery following wildfire in seeded and unseeded sagebrush steppe. Journal of Range Management 48:386-391.
- Rew, L., B. Maxwell, M. Lavin, T. Brummer, and K. Taylor. 2012. Survey, monitoring and predicting the occurrence and spread of native and non-native plant species at the Idaho National Laboratory, Bozeman, MT.