Long-Term Vegetation Transects – Monitoring Recovery on the T-17 Fire Plots (2015)
Return to Research 2015
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
The CCA for Greater Sage-grouse (DOE-ID and USFWS 2014) requires that post-fire vegetation management strategies address specific targets and objectives. Specific requirements may include: active restoration decisions be made within a short time period subsequent to a fire, risk of poor native recovery or weed invasion be assessed in post-fire communities, and recommendations for burned areas include targeting locations that may benefit most from active restoration practices. Although previous fire recovery studies on the INL Site (e.g., Ratzlaff and Anderson 1995, Buckwalter 2002) provide a solid general philosophy for managing pre-fire communities in a manner consistent with promoting the return of good condition post-fire vegetation, results from these studies aren’t detailed enough for developing post-fire recommendations specific to a burn or to a plant community.
The aforementioned studies were conducted entirely post-fire, and pre-burn conditions were extrapolated from general conditions reported for plant communities across the INL Site. Because pre- and post-burn communities were not colocated, study results offered little direction for specific scenarios, such as enhancing shrub recovery in the short term or identifying specific events or conditions that may shift the recovery trajectory of a plant community to a less desirable state. More detailed information about pre- and post-burn plant communities are needed to develop the specific, localized post-fire vegetation management strategies that may be required by current conservation goals. The opportunity to collect the type of data necessary to address post-fire recovery within context of pre-burn condition at a specific location presented itself in 2011.
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 10-1), providing a unique opportunity to monitor fire recovery on a number of plots that were recently sampled and had been well-characterized for more than half a century prior to the fire. Sampling of these 11 plots several years post-fire will facilitate assessment of the burned area in a condition comparable to that of new burns where post-fire assessments may be necessary. However, sampling the burned LTV plots provides the benefit of being able to interpret post-fire vegetation composition within the context of site-specific pre-burn and historical data. The information generated from this short-term monitoring effort will support future restoration prioritization by providing a framework for interpreting how the potential for recovery in burned communities compares to range of variability in pre-burn communities.
Understanding not only the current condition of a site but also its status in terms of its potential historical range of variability can be a powerful tool for determining the need for active restoration. For example, lack of precipitation could result in the slow recovery of native grasses during the growing season immediately post-fire, when an assessment would be conducted. In many cases, it would be difficult for the person conducting the assessment to know whether post-fire abundance of native grasses was simply an ephemeral precipitation response or whether it signaled an irreversible decline in condition that was not apparent pre-fire. The characterization of pre- and post-fire conditions of the T-17 plots could be used to provide some longer-term perspective to specific pre- and post-fire data points for future fires, which would help determine whether native grass abundance in new burns truly deviates from historical patterns. This is true for not only native grasses but also for assessing the risk of other factors that may affect post-fire recovery, like increases in cheatgrass density/frequency, loss of diversity, and delayed recovery of shrub species.
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. Issues affecting post-fire recovery that 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.
Ultimately, this monitoring effort will be used to help build a framework for assessing post-fire risk. In the future, CCA Habitat Condition monitoring plots may be used to help define the pre-burn condition of a burned area under consideration for active restoration. The pre-fire plot data, along with site-specific post-fire assessments, may be compared to similar points in time from pre- and post-burn conditions on the 11 burned LTV plots. Interpretation of these “point-in-time” comparisons within the context of the historical range of variability from the burned LTV plots will help natural resource specialists determine if the condition of burned area under consideration is within the possible range of variation for healthy communities or has deviated from that range and may require active restoration.
Accomplishments through 2015:
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, 2013, and 2014 we sampled the 11 plots that burned in the T-17 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 10-1). This result indicates established perennial grasses readily resprout post-fire, and this response 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 10-1). 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.
Precipitation patterns between 2011 and 2015 have been conducive for short-term assessment of variability in post-fire plant communities (Figure 10-2). The second growing season post-fire (2013) was the driest on record since precipitation data collection began in 1950. Some of the wettest seasonal events have also occurred within the same five-year period. October precipitation immediately following the T-17 fire was several times higher than average, August 2014 was the wettest August on record, and precipitation in May 2015 was double average values. This range of precipitation scenarios has the potential to produce a highly variable range of post-fire vegetation responses, which will help with characterization of variability during the first few years post-fire.
Plans for Continuation:
Monitoring these 11 plots annually for the five 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. 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:
Forman, A. D., J. R. Hafla, and R. D. Blew, 2013, The INL 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.
- 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.