Fire Ecology Annual Report 2016 - Monitoring and Inventory

By Jennifer L. Barnes and Jennifer L. Hrobak

Monitoring and inventories are utilized by the fire ecology program to provide feedback to the NPS fire management program on activities such as fuels treatments and to continue to gain a better understanding of the effects of wildfire on the landscape. Table 2 provides a list of the number of plots measured in 2016 and the total number of fire/fuels monitoring or inventory plots established in Alaska parks since 2003.

During 2016 the NPS Alaska fire ecology program re-measured mechanical fuels reduction plots in Wrangell-St. Elias in McCarthy and established permanent fire effects monitoring plots in Denali to measure the impacts of shortened fire return intervals. Brief descriptions and preliminary results from the two monitoring projects are provided below.

Wrangell-St. Elias McCarthy University Subdivision Fuels Reduction Monitoring

The rural community of McCarthy is located in a natural setting of boreal forest in south central Alaska within the boundaries of Wrangell-St. Elias National Park and Preserve (WRST). In 2011 a 36 acre fuels treatment project was conducted adjacent to the remote community of McCarthy, Alaska. The McCarthy University Subdivision Hazard Fuels Reduction project was designed to aid in the protection of human infrastructure and human lives in the event of a wildland fire near the community of McCarthy. The primary purpose of this fuels reduction project was to create a buffer zone, or shaded fuel break, between NPS land and private property in the University Subdivision area. The area was a mix of closed to open black spruce (Fig. 3), open mixed white and black spruce (Fig. 4) and open deciduous forests of aspen or balsam poplar forests. There was an abundance of old fire history evidence on the ground (burned logs and stumps) at the site, indicating the area burned in the past and had a good potential to burn again.

The specific fuels reduction project objectives were as follows:

• 6' Bole spacing between needleleaf trees- needleleaf trees will be mechanically thinned; needleleaf tree bole spacing will be 6 feet between tree boles.
• Needleleaf tree limbing to ≥ 5 feet- needleleaf trees will be mechanically limbed; live and dead ladder fuels lower than 5 feet up the tree bole from the ground surface will removed.
• Large woody debris removed- 100hr and 1000hr fuels will be removed by hand; 80% of 100hr and 1000hr fuels will be removed.
• Tall shrub density reduction- dead and decadent shrubs will be mechanically thinned; 80% of shrubs greater than 50% dead will be removed.
• Deciduous trees retained- live deciduous trees will not be removed.

The fire ecology program worked with the park and fire managers to develop a monitoring program to 1) document the pre- and post-treatment condition of the vegetation and fuels at the fuels treatment site, 2) assess if prescriptions were met, and 3) model changes in fire behavior for the site. Twenty-seven plots were installed to evaluate the success of the mechanical fuels treatment in meeting prescription objectives. Pre-treatment monitoring data was conducted early in the summer of 2011, the hazard fuels reduction treatment was implemented in late summer of 2011. One year post-treatment monitoring occurred in 2012 and five year post-treatment monitoring occurred in 2016. One plot (MUS-30) was within a road buffer area that was not thinned and was excluded from the analyses presented below.

Photos in Fig. 3 show McCarthy fuels treatment monitoring plot (MUS-03) are shown from left to right; pre-treatment (2011), 1 year post treatment (2012) and 5 years post treatment (2016).

Photos in Fig. 4 show the monitoring plot (MUS-14) from left to right; pre-treatment (2011), 1 year post treatment (2012) and 5 years post treatment (2016).

Figure 3. Dense black spruce and dead willow in the Wrangell St. Elias McCarthy University Subdivision fuels break were thinned and limbed in 2011 to provide a fuel break in the event of a wildfire. NPS photo.

Figure. 4 White and black spruce trees in the Wrangell St. Elias McCarthy University Subdivision site were thinned and limbed in 2011 to provide a fuel break in the event of a wildfire. The dead and dying tall willows were also cut, but have grown back in 5 years (note the tall shrubs in the background). NPS photo.

Based on the 2016 monitoring plots, the prescribed thinning of spruce trees to 6 foot bole spacing was maintained. Similar to the 2012 monitoring data, the prescription was exceeded. Six foot bole spacing would result in approximately 1210 trees/acre. The five year post-treatment plots in 2016 had an average of 605 (80% CI 470 - 739) spruce trees/acre, reduced from the initial pre-treatment density of 1081 (80% CI 892-1302) spruce trees/acre (Fig. 5, Table 3). Although the prescription was written for bole spacing, the pre-treatment crown spacing was approximately 2 feet based on an average density of 1081 trees/acre with an estimated 2 foot crown radius. The fuels treatment increased the crown spacing to approximately 4.5 feet between tree crowns. The treatment opened up the spruce canopy which should help reduce the potential for crown fire.

Some deciduous trees (aspen and balsam poplars) were cut during the treatment, which resulted in a slight reduction in deciduous tree densities at the plots one year after the treatment (Fig. 5). The cut trees caused the aspen and balsam poplars to sucker or re-sprout and were observed 1 year post treatment, but they were not tall enough to tally as trees (>4.5 feet tall). By 5 years post treatment the aspen and poplar suckers were tall enough to be tallied as trees in many of the plots. Five years after the treatment the density of deciduous trees increased from an average of 156 trees/acre (80% CI 93-214) pre-treatment to 377 trees/acre (80% CI 179-575) five years after the treatment (Fig. 5). In general aspen and balsam poplar are less flammable than spruce, so this change will likely contribute to creating a better fuel break.

The fuels treatment significantly improved the ladder fuel heights at the site. Prior to treatment the average height from the ground to the lowest dead branches on spruce trees was less than 1 inch (1.5 cm) above the ground (Fig. 6, Table 3). In 2016 the average height to the lowest dead branches on spruce trees was 3.4 feet (104 cm) and the lowest live branches average was 4.6 feet (139 cm) (Fig. 6). Neither of these heights achieved the objective of the 5 foot limbing height prescription, but the increased crown base height still reduces the potential for surface fires to move into the canopy.

The project area was in an old fire area that likely resulted in a lot of willow shortly after the fire. Over time as the trees have overtopped the willow in the area, the willows have died back resulting in lots of dead and broken willow stems prior to the treatment (note the dead willow in the 2011 photos in Fig. 3 and 4). The dead and decadent tall shrubs were reduced by 87%, which met the target objective of 80% reduction (Table 3, Fig. 7). There was an average of 734 shrubs/acre (80% CI 591-876) of tall dead or decadent shrubs prior to the treatment; these were reduced to 105 shrubs/acre (80% CI 56-154) 1 year after the treatment and have been maintained by 5 years after the treatment with an average of 90 shrub/acre (80% CI 59-120) (Table 3, Fig. 7).

However, the cutting of the decadent willows has resulted in vigorous re-sprouts from the cut willow. The number of live willow shrubs has increased from 960 shrubs/acre (80% CI 785-1135) pre-treatment to 1728 shrubs/acre (80% CI 1434-2021) 5 years after the treatment. Further discussions and assessment of whether the increased shrub density will impact fire potential or impede access to the fuels treatment during the event of fire will take place this spring.

Pre-treatment (n=26 plots):
1081 (868-1293) trees/acre
1 yr Post-treatment (n=26 plots):
563 (443-682) trees/acre
5 yrs Post-treatment (n=26 plots):
605 (470-739) trees/acre | Yes, but exceeded bole spacing | 2016
(2011 - 2016) |
| WRST McCarthy University Subdivision Fuels Treatment | Limb spruce to 5 ft (152 cm) | Dead Ladder Fuel height
Pre-treatment (n=181 trees):
1.48 cm (0.98 – 1.97 cm)
1 yr Post-treatment (n=158 trees):
78.4 cm (70.9 – 85.9 cm)
5 yrs Post-treatment (n=160 trees): 103.9 cm (97.4 - 110.5 cm) | No, average was 3.4 ft | 2016
(2011 - 2016) |
| WRST McCarthy University Subdivision Fuels Treatment | 80% of tall shrubs that are greater than 50% dead will be removed | Dead/Decadent Shrub Density
Pre-treatment (n=27 plots):
745 (608-883) shrubs/acre
1 yr Post-treatment (n=26 plots):
105 (56-154) shrubs/acre
5 yrs Post-treatment (n=27 plots):
98 (67-130) shrubs/acre Percent removed: 86.8% | Yes | 2016
(2011 - 2016) |

Denali Shortened Fire Return Interval Monitoring

In managing fires, recently burned areas are often used as natural fuel breaks by fire managers in Alaska, yet the reliability of this assumption seems to be changing with changing climate. In 2015 and 2016 some fires in the Alaska parks burned into recently burned area, leading to the question of the longevity and effectiveness of recently burned areas providing effective fire breaks or fire slowing conditions. In addition, little monitoring has occurred to understand and reasonably predict vegetation successional pathways due to fire burning a vegetated stands on multiple occasions (repeat fire events) with various levels of burn severity. In 2016, AKR NPS Regional Fire Ecology program partnered with USGS, FWS, BLM Alaska Fire Service, and the State of Alaska, DNR DOF in a preliminary study to assess the: 1) extent and trends in repeat fire (reburn) in Alaska; 2) characteristics that allow older fires to act as fuel breaks for new wildfires; 3) evaluate what climatic, weather and fuels conditions do fires reburn recently burned areas; and 4) evaluate the impacts of shortened fire return intervals and reburns have on vegetation succession and composition.

The 2015 Carlson Lake fire in Denali burned into the 2000 Foraker fire (and other fires) and burned 8 plots that had been established after the 2000 fire. In 2016, the team re-measured 7 of the 8 plots that burned both in 2015 and 2000 and re-measured 4 plots that were only burned in the 2000 fire.

Monitoring goals for the fire monitoring plots included:

• Document vascular and non-vascular plant cover changes
• Document changes in active layer depths
• Monitor tree seedling establishment
• Document changes in tree densities by diameter size class

The plots sampled were of two general vegetation types prior to the fires: 1) lowland woodland black spruce with tussocks (Fig. 8) and 2) mesic black/white spruce with feathermoss (Fig. 9). The mesic spruce sites burned with higher severity under both fires than the woodland black spruce sites. Seven years after the 2000 fire the three mesic spruce plots had paper birch (Betula neoalaskana) establishing. The 2015 burned top-killed many of the sapling paper birch, but many were re-sprouting after the second fire. Forb cover (fireweed) increased after the second fire at the mesic spruce sites. Over all the mesic spruce sites had less vegetation cover than the lowland woodland black spruce sites (Fig. 10 and Table 4) after the initial and second fire. The lowland black spruce sites were dominated by tussock sedges (Eriophorum vaginatum) and shrubs (Ledum palustre, Betula nana, Vaccinium uliginosum) after the first fire (Post Burn Year 7 and 16) and after the second fire (Post Burn Year 1 x2 Fires). The lowland black spruce sites revegetated quickly after the fires due to the ability of many of the plants to re-sprout post fire. These sites appear to be more resilient to multiple burns.

Preliminary analysis indicates that even with a second burn, seedling spruce survived or regenerated after the second fire. The average density of black spruce seedlings at the twice burned lowland spruce sites was 8,318 spruce seedlings/acre, while the once burned sites had an average of 6,407 spruce seedlings/acre. The data was variable with the small sample size. Additional analyses will be completed on these plots and other sites that have been monitored in the past. The work will continue next year in Wrangell-St. Elias, where the 2016 Steamboat Creek fire burned within the 2009 Chakina fire.

Figure 8. This lowland woodland black spruce tussock site in Denali was burned by the 2000 Foraker fire and the 2015 Carlson Lake fire. The photo on the left was taken in 2002, 2 years after the 2000 fire. A re-measurement of the same plot in 2007 (middle) shows increased low shrubs, 7 years after the fire. In 2015 the plot was burned again, and the photo on the right shows the plot in 2016 with multiple burns, low shrubs and tussocks have re-sprouted after the second fire.

Figure 9. White and black spruce mixed forest in Denali was burned in 2000 and again in 2015. The photo on the left was taken 2 years after the fire (2002). A re-measurement of the same plot in 2007 (middle) shows paper birch saplings, low shrubs and downed trees 7 years after the fire. In 2015 the plot was burned again, and the photo on the right shows the plot in 2016 with multiple burns.

Figure 10. Average cover of vascular plants by life form from the Foraker-Carlson Lake fire monitoring plots in Denali. Overall the woodland black spruce forest types appear more resilient to multiple fires.

Data Management

Data for all recent monitoring projects have been entered into FFI (FEAT/FIREMON Integrated) - a plot-level monitoring sequel server software tool designed to assist managers with collection, storage and analysis of ecological information (http://www.frames.gov/partner-sites/ffi/ffi-home/). Digital archives and metadata for the AK databases were uploaded to the NPS Data Store IRMA in Feb 2017. The Alaska Eastern Area fire ecology data set is located here and includes data for YUCH and WRST: https://irma.nps.gov/DataStore/Reference/Profile/2238367 and the Alaska Western Area fire ecology data set includes data for DENA, NOAT, BELA, and LACL: https://irma.nps.gov/DataStore/Reference/Profile/2238363. The updated FFI databases reflect the recent data additions and QC to the AK NPS fire ecology databases (Table 5).

Part of a series of articles titled
National Park Service Alaska Region Fire Ecology Annual Report Calendar Year 2016.

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NPS Alaska Region Fire Ecology Annual Report Summary

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Fire Ecology Annual Report 2016 - Research and Technology

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