The climate data show that the 14 years from 2008 to 2021 were 13 mm wetter than the 30-year mean with a 0.5°C higher maximum temperature and 0.1°C higher minimum temperature (Table 1). The critical years just before, during, and just after the fire (2007, 2008, and 2009) had 45 to 73 mm less precipitation than normal, with no more than 141 mm of precipitation in any year. Wetter years occurred in 2006, 2010, 2016, and 2019, with 28–55% more precipitation than normal.
Table 1
Climate data from Hiko, Nevada weather station 2006–2022.
Year | Ppt a | Δ Ppt b | Tmaxc | Δ Tmaxd | Tmine | Δ Tminf |
2006 | 272 | 48.6 | 23.1 | 1.8 | 5.1 | -7.2 |
2007 | 133 | -27.4 | 23.9 | 5.2 | 5.0 | -9.1 |
2008 | 141 | -22.8 | 23.3 | 2.6 | 4.8 | -12.7 |
2009 | 113 | -38.5 | 23.4 | 3.1 | 5.0 | -9.1 |
2010 | 272 | 48.9 | 22.6 | -0.4 | 5.1 | -7.2 |
2011 | 108 | -40.9 | 22.9 | 0.8 | 4.1 | -25.5 |
2012 | 169 | -7.5 | 24.4 | 7.4 | 6.3 | 14.5 |
2013 | 181 | -1.3 | 22.9 | 0.8 | 5.2 | -5.5 |
2014 | 168 | -8.1 | 23.6 | 4.0 | 6.2 | 12.7 |
2015 | 187 | 2.2 | 23.2 | 2.2 | 6.5 | 18.1 |
2016 | 234 | 27.6 | 22.9 | 0.8 | 5.9 | 7.2 |
2017 | 186 | 1.8 | 23.6 | 4.0 | 6.3 | 14.5 |
2018 | 119 | -35.0 | 23.4 | 3.1 | 6.1 | 10.9 |
2019 | 283 | 54.6 | 21.3 | -6.1 | 5.1 | -7.2 |
2020 | 98 | -46.5 | 23.8 | 4.8 | 5.2 | -5.5 |
2021 | 121 | -33.9 | 23.4 | 3.1 | 5.6 | 1.8 |
2022 through July | 38 | | | | | |
14-year meang | 199 | 6.9 | 23.2 | 2.2 | 5.5 | 1.9% |
30-year meanh | 186 | | 22.7 | | 5.4 | |
a Mean annual precipitation in mm |
b Percent difference between Ppt and the 30-year mean |
c Mean annual maximum temperature in °C |
d Percent difference between Tmax and the 30-year mean |
e Mean annual minimum temperature in °C |
f Percent difference between Tmin and the 30-year mean |
g 14-year mean calculated from 2008 to 2021 |
h 30-year mean calculated from 1992 to 2021 |
In the burned areas, C. ramosissima mean density was 1.06 clumps/m2 in 2009, 0.30 clumps/m2 in 2010, 0.35 clumps/m2 in 2011, 0.36 clumps/m2 in 2018, 0.41 clumps/m2 in 2019, 0.64 clumps/m2 in 2020, 0.41 clumps/m2 in 2021, and 0.48 clumps/m2 in 2022 (Fig. 3). C. ramosissima seedlings were already present the first year following fire at all but one plot. Seedlings were observed to have germinated in 2009, 2010, 2011, 2019, and 2020. In 2022, C. ramosissima density was 0.76 clumps/ m2 in the adjacent unburned areas. Total shrub density was 0.81 per m2 in the adjacent unburned areas. The adjacent unburned areas contained ten shrub species including two species that were not represented in the post-burn community.
A repeated measures ANOVA using Greenhouse-Geisser corrections blocked by fire determined the mean total (mature and seedling) C. ramosissima density significantly differed between years (F1.223, 19.573 = 7.338, p = 0.01). However, there was no significant effect due to fire (F1,16=0.908, p = 0.355), implying the results were consistent between fires. There was no significant interaction between year and fire (F1.223,19.573=0.535, p = 0.508). Post-hoc tests using a Bonferroni correction revealed that year 2020 was significantly different from years 2010, 2011, 2018, 2019, and 2021 (p = 0.002 to p = 0.038), 2010 different than 2018, 2019, 2021, and 2022 (p = 0.002 to p = .035), and 2011 different than 2022 (p = 0.011).
A repeated measures ANOVA using Greenhouse-Geisser corrections blocked by fire determined that the mean C. ramosissima cover differed between years (F1.173, 18.764 = 35.574, p < 0.001). However, there was no significant effect from comparing the two fires (F1,16 =2.338, p = 0.146) or the interaction between year and fire (F1.173, 18.764 = 1.967, p = 0.177). Post-hoc tests using a Bonferroni correction revealed that years 2009, 2010, and 2011 were similar. Years 2018 and 2021 were similar. Years 2019, 2020, 2021, and 2022 were similar (Fig. 4).
Mean cover increased each year from 2009 to 2020. Mean cover regressed slightly in 2021 but remained high and increased slightly again in 2022. A significant regression equation (F1,142 =120.2, p < 0.001), with an R2 of 0.458, fit with the C. ramosissima cover increase since the fires (Fig. 5). The C. ramosissima predicted cover is equal to -1.54 + 1.06*[years since fire]. By 2018, cover was at least 2.5% at every plot monitored.
The repeat photography sequences show visible change in the shrub community at the permanently established plots (Figs. 6 and 7). Small seedlings are present in 2009 and 2010. By 2011, growing C. ramosissima are visible in the photos. The individuals continue to grow through 2020 and persist through 2022. The change in individuals can be directly observed from year to year in the photos.
Total vegetation cover ranged from 2.6% in 2009 to 81% in 2019 in the burned areas (Table 2). Annual cover was highly variable based on precipitation. Dominant functional groups on the burned area varied from year to year. Annual forbs dominated cover in 2009, 2010, 2019, and 2020. Annual grasses had the most cover for a single year in 2011. Shrubs dominated in 2018 when monitoring occurred in the winter. Shrubs also dominated in 2021 and 2022 which were dry years. Non-native species were present in the post-burn community and accounted for 20–73% of total cover.
Table 2
Mean vegetation cover a by native status and functional group for Fossil and Jacob Fires combined
| | 2009 | 2010 | 2011 | 2018 | 2019 | 2020 | 2021 | 2022 |
Non-native | Annual Graminoid | 0.4 | 2.9 | 9.7 | 2.9 | 3.7 | 16.9 | 1.1 | 6.3 |
Annual Forb | 0.8 | 1.7 | 2.2 | 7.4 | 32.7 | 12.2 | 0.1 | 0 |
Native | Annual Graminoid | 0.4 | 0.6 | 7.2 | 0 | 0.1 | 0.3 | 0 | 0 |
Annual Forb | 0.6 | 17.5 | 4.5 | 1.8 | 5.4 | 34.3 | 0.1 | 3.5 |
Perennial Graminoid | 0.0 | 0.0 | 0.0 | 0.1 | 0.2 | 0.3 | 0.1 | 0.2 |
Perennial Forb | 0.1 | 0.6 | 2.6 | 2.1 | 1.0 | 1.4 | 0.3 | 0.8 |
Shrub | 0.2 | 0.7 | 1.1 | 10.4 | 12.8 | 15.5 | 13.2 | 14.7 |
Subtotals | Annual Graminoids | 0.8 | 3.5 | 16.9 | 2.9 | 3.8 | 17.3 | 1.1 | 6.3 |
Annual Forbs | 1.4 | 19.3 | 6.7 | 9.1 | 38.1 | 46.5 | 0.1 | 3.5 |
Perennials | 0.3 | 1.4 | 3.7 | 12.5 | 14.3 | 17.2 | 13.5 | 15.7 |
Non-natives | 1.2 | 4.8 | 12.3 | 10.3 | 36.4 | 59.5 | 1.2 | 9.5 |
Natives | 1.3 | 19.3 | 15.1 | 14.3 | 19.7 | 21.5 | 13.5 | 16.1 |
TOTAL | | 2.6 | 24.1 | 27.4 | 24.6 | 56.1 | 81.0 | 14.7 | 25.6 |
a Values given in percent |
There were 117 plant species recorded during the study, but just five species comprised 52–88% of the relative vegetation cover during monitoring (Table 3). The annuals were highly variable with primary dominants storksbill filaree (Erodium cicutarium), an invasive annual forb; whitestem blazingstar (Mentzelia albicaulis), a native annual forb; red brome (Bromus rubens), an invasive annual grass; and sixweeks fescue (Vulpia octoflora), a native annual grass. C. ramosissima increased in absolute cover from 2009 to 2020 before decreasing slightly in 2021. During winter monitoring in 2018, C. ramosissima was dominant with 37% relative cover. During summer monitoring in 2019, C. ramosissima (20% relative cover) was codominant with E. cicutarium (50% relative cover). In 2020, B. rubens (21% relative cover) and E. cicutarium (37% relative cover) were codominant. In 2021, C. ramosissima was dominant again (77% relative cover). In 2022, C. ramosissima (46% relative cover) and B. rubens were codominant. In 2022, C. ramosissima absolute cover was 35.3% in the adjacent unburned areas. Total cover was 49.1% in the adjacent unburned areas.
Table 3
Absolute and relative covera of the most common species on the burned area: blackbrush (Coleogyne ramosissima), red brome (Bromus rubens), storksbill filaree (Erodium cicutarium), whitestem blazingstar (Mentzelia albicaulis), and sixweeks fescue (Vulpia octoflora)
| | 2009 | 2010 | 2011 | 2018 | 2019 | 2020 | 2021 | 2022 |
Coleogyne ramosissima | AbsCVb | 0.0 | 0.3 | 0.7 | 9.1 | 11.0 | 12.9 | 11.3 | 11.7 |
% of Perennial | 0.0 | 23.0 | 18.6 | 72.7 | 78.6 | 75.0 | 87.7 | 74.5 |
| RelCVc | 0.0 | 1.3 | 2.5 | 37.0 | 19.6 | 15.9 | 76.9 | 45.7 |
Bromus rubens | AbsCVb | 0.4 | 2.9 | 7.1 | 2.5 | 3.7 | 16.7 | 1.0 | 6.3 |
| RelCVc | 15.4 | 12.0 | 25.9 | 10.1 | 6.6 | 20.6 | 6.8 | 24.6 |
Erodium cicutarium | AbsCVb | 0.8 | 1.6 | 2.0 | 1.3 | 26.9 | 30.3 | 0.1 | 3.1 |
RelCVc | 30.1 | 6.6 | 7.3 | 5.3 | 47.9 | 37.4 | 0.7 | 12.4 |
Mentzelia albicaulis | AbsCVb | 0.6 | 15.9 | 0.1 | 0 | 0.1 | 0.1 | 0 | 0.1 |
RelCVc | 23.1 | 66.0 | 0.4 | 0 | 0.2 | 0.1 | 0 | 0.4 |
Vulpia octoflora | AbsCVb | 0.4 | 0.5 | 7.2 | 0 | 0.1 | 0.3 | 0 | 0 |
| RelCVc | 15.4 | 2.1 | 26.3 | 0 | 0.2 | 0.4 | 0 | 0 |
All Others Combined | RelCV | 14.7 | 2.9 | 10.3 | 11.8 | 14.3 | 20.9 | 2.4 | 4.6 |
a Values given in percent |
b Absolute cover |
c Relative cover |
Bold values indicate dominant species with relative cover equal to or exceeding 20% |