Research Project Summary: Effects of prescribed fires in semidesert plant communities in southeastern Arizona



RESEARCH PROJECT SUMMARY CITATION:
Smith, Jane Kapler, compiler. 2008. Research Project Summary: Effects of prescribed fires in semidesert plant communities in southeastern Arizona. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [ ].

Sources:
This summary covers a suite of studies conducted in southeastern Arizona during the 1970s through the 1990s. The research describes effects of both wildfires and prescribed fires. The fire dates and relevant publications are listed here in chronological order:

1974Wildfires in February and April:
Bock, Jane H.; Bock, Carl E.; McKnight, J. Robert. 1976. A study of the effects of grassland fires at the research ranch in southeastern Arizona. Arizona Academy of Science. 11(3): 49-57. [9].

1975-1976Wildfires in mid-May and mid-June, 1975 , and February 1976 :
Bock, Carl E.; Bock, Jane H. 1978. Response of birds, small mammals, and vegetation to burning sacaton grasslands in southeastern Arizona. Journal of Range Management. 31(4): 296-300. [1].

1984Prescribed fires conducted in July:
Bock, Jane H.; Bock, Carl E. 1987. Fire effects following prescribed burning in two desert ecosystems. Final Report: Cooperative Agreement No. 28-03-278. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 20 p. [7].

Bock, Jane H.; Bock, Carl E. 1992. Short-term reduction in plant densities following prescribed fire in an ungrazed semidesert shrub-grassland. The Southwestern Naturalist. 37(1): 49-53. [8].

1987Wildfire in July:
Bock, Carl E.; Bock, Jane H. 1991. Response of grasshoppers (Orthoptera: Acrididae) to wildfire in a southeastern Arizona grassland. The American Midland Naturalist. 125: 162-167. [2].

Bock, Carl E.; Bock, Jane H. 1992. Response of birds to wildfire in native versus exotic Arizona grassland. The Southwestern Naturalist. 37(1): 73-81. [3].

Bock, Carl E.; Bock, Jane H. 1997. Shrub densities in relation to fire, livestock grazing, and precipitation in an Arizona desert grassland. The Southwestern Naturalist. 42(2): 188-193. [4].

Bock, J. H.; Bock, C. E. 1992. Vegetation responses to wildfire in native versus exotic Arizona grassland. Journal of Vegetation Science. 3: 439-446. [6].

SPECIES INCLUDED IN THE SUMMARY:
Common names are used throughout this summary except for insect species. For a list of the common and scientific names of species discussed in this summary and for links to FEIS species reviews, see the Appendix.

STUDY LOCATION:
All studies were conducted on the Appleton-Whittell Research Ranch, located in the foothills of the Huachuca Mountains, Santa Cruz County, Arizona [1,3,7,9].

SITE DESCRIPTION:
The study area is at 1,400 to 1,500 m elevation [2]. Average temperatures range from a January minimum of -2.9 C to a June maximum of 34.9 C [6]. Mean annual precipitation, based on a summer rainy season and its preceding winter, averages 430 mm, with half to two-thirds occurring in summer (July-September). The study area was grazed until about 1969, when grazing was eliminated [7].

PREFIRE PLANT COMMUNITY:
Plant communities in the study area include semidesert grassland, oak savanna, and Madrean oak woodland, hereafter called grassland, savanna, and woodland [7,9]. The savanna type is not described in detail. Grassland sites supported grasses, shrubs, scattered honey mesquite trees [6], and scattered low shrubs [2,3]. Areas in the grassland type were seeded prior to 1960 with mixtures of Lehmann lovegrass and weeping lovegrass are referred to in this Summary as "nonnative grasslands". On seeded sites, native herbaceous cover was generally less than half that on unseeded sites ("native grasslands") [5]. Emory oak and Arizona white oak dominated the overstory in the woodland type, and grasses dominated the understory. Forb cover was about 10% in both grasslands and woodlands. Prefire cover of herbaceous and woody species on the grassland site treated in 1984 with prescribed fire is listed in Table 1 and Table 2; prefire cover on the woodland site is listed in Table 3 and Table 4 [7].

Based on the description provided by Bock and Bock [2,3,7,8], vegetation on the study sites could be classified in the plant communities and probably historically experienced the fire regimes described in Table 5.

Table 5. Fire regime information on the vegetation communities studied in the research reported in this Summary. For each community, fire regime characteristics are taken from the LANDFIRE Rapid Assessment Vegetation Models [12]. These vegetation models were developed by local experts using available literature, local data, and expert opinion as documented in the pdf file linked from the name of each Potential Natural Vegetation Group listed below. Cells are blank where information is not available in the Rapid Assessment Vegetation Model.
Vegetation Community (Potential Natural Vegetation Group) Fire severity* Fire regime characteristics
Percent of fires Mean interval
(years)
Minimum interval
(years)
Maximum interval
(years)
Desert grassland with shrubs and trees Replacement 85% 12    
Mixed 15% 70    
Madrean oak-conifer woodland Replacement 16% 65 25  
Mixed 8% 140 5  
Surface or low 76% 14 1 20
*Fire Severities:
Replacement=Any fire that causes greater than 75% top removal of a vegetation-fuel type, resulting in general replacement of existing vegetation; may or may not cause a lethal effect on the plants.
Mixed=Any fire burning more than 5% of an area that does not qualify as a replacement, surface, or low-severity fire; includes mosaic and other fires that are intermediate in effects.
Surface or low=Any fire that causes less than 25% upper layer replacement and/or removal in a vegetation-fuel class but burns 5% or more of the area [10,11].

PLANT PHENOLOGY:
The fires studied in this research occurred from February through July in various years. All fires occurred before summer rains had begun. Since most plant growth in desert and semidesert ecosystems occurs after summer rains begin, most plants were probably dormant during the fires. The only study actually indicating plant phenology is Bock and Bock 1991 [2], in which the authors comment that summer rains came late in 1987, so plants were dormant during the July 1987 wildfires.

FIRE SEASON/SEVERITY CLASSIFICATION:
1974 February and April wildfires: winter to spring/low to moderate
1975 mid-May and mid-June wildfires: summer/low to moderate
1976 February wildfire: winter/low to moderate
1984 25 May and 12 June prescribed burns: summer/moderate
1987 16-17 July wildfire: summer/moderate

FIRE DESCRIPTION:
Objectives: For all studies, research aimed to compare changes in vegetation and/or wildlife in burned areas with that in unburned areas. The 1984 prescribed fire study had one additional objective: to quantify fire behavior and intensity.

Fire behavior: Fire behavior is not described for the 1974, 1975, or 1976 wildfires.

The 1984 prescribed fires occurred when weather was hot and dry (Table 6) [7].

Table 6. Burning conditions for 2 prescribed fires conducted in southeastern Arizona in summer 1984 [7].
Plant community Burn date & time Air temperature (C) Relative humidity (%) Wind speed Dead fine fuel moisture (%) Spread rate (m/min) Flame length (m) Fireline intensity (kW/m)
Oak woodland 25 May 1984, 1000-1200 32-33 16-18 gusting from 5-10 mph 5-6 0.5-1.5* 0.2-0.5* 8-58*
Semidesert grassland 12 June 1984, 1000-1130 29-31 13-16 gusting from 5-22 mph 5-6 1-4 0.8-1.4 160-540
*These data describe 4 of 5 burn plots in woodland. In the 5th burn plot, fire spread was much more rapid (30 m/min), and heat release was estimated at 260 kW/m; fires were of shorter duration and ignition of plant materials was less complete than in other plots on this site.

The 1987 wildfire occurred during hot, dry, very windy weather. Maximum temperature on the 2 days of the fire was 29 C, and minimum relative humidity was 21%. Winds averaged about 15 mph, gusting to 30 mph. Most aboveground vegetation was consumed, with the exception of the basal stems of some shrubs and the trunks and large branches of honey mesquite [2,3,6].

FIRE EFFECTS ON PLANT AND ANIMAL COMMUNITIES:
In general, the fires increased bare ground and reduced vegetation cover for 1 growing season, but cover increased in the 2nd year after fire, often to prefire levels. In the first year after fire, forbs often increased while grasses decreased. The fires caused little mortality in woody species, though some caused extensive top-kill. In many cases, fire effects could not be clearly distinguished from climate effects; in desert and semidesert ecosystems, abundance of herbaceous vegetation can vary substantially from year to year depending on precipitation. Fire effects on birds, small mammals, and insects (grasshoppers) were related to individual species' food requirements, mobility, and other habitat needs. Fire effects are described here according to the chronological order of the burns studied.

1974 February and April wildfires: The February wildfire occurred in savanna, and the April fire occurred in grassland. In the first year after the fires, grass cover in both savanna and grassland habitat was significantly less on burned than unburned plots, and forb cover was significantly greater (P<0.01). A calculation of similarity between burned and unburned plots indicated that, in postfire year 1, burned plots were approximately 80% similar to control plots; by postfire year 2, the similarity had increased to approximately 90% [9].

Some species of small mammals decreased during the time of postfire observations (6-19 months after the February fire, 3-16 months after the April fire); no small mammal populations increased significantly in burned areas during the study. Western white-throated woodrats were significantly (P<0.005) less abundant on burned than control plots (burned in the April fire), likely because their ground nests were destroyed by fire. Hispid cotton rats were significantly (P<0.005) reduced on February-burned plots, probably because of reduced grass cover. Pocket mice were usually found in "relatively open areas", but they were sparse on the February burn (P<0.005), which may have been too open to be suitable habitat. Other mammals observed on both burned and unburned plots, with no significant differences, included spotted ground squirrels, western harvest mice, deer mice and white-footed mice (combined in this report), northern pygmy mice, and southern grasshopper mice [9].

Birds were more abundant in burned than unburned habitat during the first 16 to 19 months after these wildfires. In the savanna (February burn), this was due mainly to increases in mourning doves and chipping sparrows. These 2 species were also abundant after fire in the grassland (April burn), as were some flycatchers and seed-eating species. Only the grasshopper sparrow, which relied upon shrubs for singing perches, was significantly reduced on both burned areas [9] (Table 7).

Table 7. Comparisons of bird species abundance on burned and unburned areas in southeastern Arizona, averaged from more than 40 censuses taken in each habitat  in the first 2 years after wildfire. "More" in a column indicates that the species was significantly more abundant on burned than unburned areas in that vegetation type. "Less" indicates the species was significantly less abundant. "No difference" indicates no significant difference (P<0.05) [9].

Species

Savanna (burned Feb. 1974) Grassland (burned April 1974)
American kestrel no difference no difference
ash-throated flycatcher no difference no difference
barn swallow no difference more
Bewick's wren no difference no difference
Cassin's kingbird no difference more
chestnut-collared longspur more no difference
Chihuahuan raven less more
chipping sparrow more more
eastern meadowlark no difference less
flicker no difference no difference
grasshopper sparrow less less
horned lark more less
house finch no difference no difference
lark sparrow no difference no difference
Montezuma quail no difference no difference
mourning dove more more
rufous-crowned sparrow no difference less
savannah sparrow no difference more
Say's phoebe no difference more
scaled quail no difference no difference
vesper sparrow no difference more

1975 mid-May and mid-June wildfires, 1976 February wildfires: In the first 2 years after these summer wildfires in big sacaton grassland, forbs were significantly more common on burned plots than on unburned plots. Big sacaton cover was significantly reduced in the 1st postfire growing season but recovered to prefire levels in the 2nd season. Other grasses, especially vine-mesquite, were significantly more abundant 1 year after the winter burn than in any other plots. Cover of dead vegetation and bare ground was significantly greater 1 year after the summer fires than after the winter fires or on control plots [1]. (P≤0.005 for all of these significant results.)

The summer-burned plots had significantly (P<0.05) more total birds than the control plots. Eleven species were found only in burned plots, whereas 4 species were found only in control plots (Table 8). The first year after fire, summer-burned plots supported significantly (P<0.05) more raptors than other habitats, probably because visibility of prey had increased. Several species of seed-eating songbirds, doves, and quail had more birds in summer-burned plots (both postfire years) than in control plots, probably because the abundance of seeds and annual forbs was greater in summer-burned than other plots [1].

Fires reduced small mammal populations on big sacaton grasslands, more on summer-burned than winter-burned plots. Hispid cotton rats, which feed mainly on green vegetation, declined after fire, whereas hispid pocket mice and kangaroo rats, which are seed-eating species, increased. Numbers of deer mice, white-footed mice, and western harvest mice were unaffected by the fires [1] (Table 9).

Table 9. Abundance of rodents after early summer wildfires in Arizona grassland. All differences noted below are statistically significant (P<0.05) [1].
Species Response
Deer mouse and white-footed mouse (not distinguished in sampling) No significant differences between burned and unburned plots
Hispid cotton rat Less abundant in summer- and winter-burned plots
Merriam's kangaroo rat and hispid pocket mouse (not distinguished in analysis) More abundant in summer-burned plots
Southern grasshopper mouse Generally more abundant in burned plots, but differences not significant
Western harvest mouse Abundance very low, no significant differences
Western white-throated woodrat Less abundant in summer- and winter-burned plots

1984, 25 May and 12 June prescribed fires: These prescribed fires were conducted in semidesert grassland with some shrub cover, and in woodland with Emory oak and Arizona oak in the overstory and a grass-dominated understory with some shrubs. Bare ground was more prevalent in the 1st year after fire on both sites (Table 10). The difference was smaller, but still significant, in the 2nd postfire year [7].

Table 10. Average cover of bare ground in 2 ecosystems in southeastern Arizona before and after summer prescribed fires [7]. Where averages from burned plots are followed by *, they are significantly (P<0.05) different from averages in control plots within the same vegetation type in the same year [7,8].
Year  % bare ground in grassland type % bare ground in woodland type
Control Burn Control Burn
Pre# 51.95 54.97 64.55 62.70
Post1 34.71 53.26* 37.37 50.70*
Post2 40.15 47.57* 54.49 61.31*
#Pre=August 1983, growing season prior to burning. Post1=August 1984, 1 year after fire. Post2=August 1985, two years after fire.

The 1984 prescribed burns reduced total aboveground herbaceous biomass on both grassland and woodland sites. On the grassland site, biomass on burned plots was reduced by more than 60% in postfire year 1 and recovered to about 50% of the original herbage in postfire year 2. Not all of this change was attributable to fire, since biomass on control plots declined about 30% in postfire year 1 and was only 90% of the prefire level in postfire year 2. On the woodland site, biomass on burned plots declined by about 50% in postfire year 1 but exceeded that on controls in postfire year 2 [7,8] (Table 11).

Table 11. Average aboveground herbaceous biomass before and after summer prescribed fires in southeastern Arizona. Where averages from burned plots are followed by *, they are significantly (P<0.05) different from averages in control plots within the same vegetation type in the same year [7,8].
Year  Biomass (g/0.25m2) in grassland type Biomass (g/0.25m2) in woodland type
Control Burn Control Burn
Pre# 54.35 58.01 34.55 28.77
Post1 36.18 18.59* 26.40 14.99*
Post2 48.18 27.73* 24.62 31.10
#Pre=August 1983, growing season prior to burning. Post1=August 1984, 1 year after fire. Post2=August 1985, two years after fire.

Fire effects on grasses were mostly limited to the first year after fire. In both grassland and woodland, grass density was significantly reduced relative to density on unburned control plots in the 1st postfire year. In the 2nd postfire year, grass density on burned plots was significantly greater than in the previous year and similar to that on control plots (Table 1 and Table 3). By the 2nd postfire year, the only grasses with significantly lower density on burned than control plots were threeawn species on the grassland site; the only grasses with significantly higher density on burned plots were sprucetop grama on the grassland site and curlymesquite on the woodland site [7,8].

Fire effects on forbs, like those on grasses, were mostly limited to the 1st postfire year. On the grassland site, forb density on burned plots was significantly reduced relative to that on control plots in postfire year 1 and similar to that on control plots in postfire year 2. On woodland plots the effect was opposite in the first year: Forb density on burned plots was significantly greater than that on control plots in postfire year 1 and similar to that on control plots in postfire year 2 (Table 1 and Table 3). By the 2nd postfire year, the only forb with significantly higher density on burned plots was toothleaf goldeneye on the woodland site; no forbs had significantly lower density on burned than control plots [7,8].

Fire effects on woody species were short lived. On grassland sites, density of wait-a-minute and velvetpod mimosa was significantly less on burned than control plots in postfire year 1. Density increased in postfire year 2, though not to the level on control plots. Density of yerba de pasmo showed little response to fire (Table 2). On woodland sites, density of shrubs and trees showed no significant responses to fire (Table 4). On both grassland and woodland sites, heights of all 3 shrub species were significantly less on burned than control plots in postfire year 1; shrubs were taller in postfire year 2, although only yerba de pasmo recovered to prefire height [7].

1987 16-17 July wildfire: This summer wildfire caused extensive but largely ephemeral alterations in grassland vegetation on stands dominated by native grasses and on stands dominated by weeping lovegrass, a nonnative species. Litter on burned sites, both native and exotic, was significantly (P<0.001) less than on unburned sites from postfire season 1 through postfire season 4, the last year reported [3]. Wildfire significantly (P<0.0001) reduced grass cover for the 1st postfire year on both native- and nonnative-dominated sites. By the 3rd postfire year, burned and unburned plots had similar grass cover [6]. Fire did not alter the proportion of nonnative grass cover on the nonnative-dominated site, which averaged about 90% [3]. Forb cover increased significantly (P≤0.002) on burned plots in the 1st postfire year, after which it was similar on burned and unburned plots. Table 12 describes the responses of individual herb species to fire [6].

Table 12. Responses of herbaceous plants to summer fire in semidesert grassland in southeastern Arizona. "X" in the "Native" or "Nonnative" column indicates the grassland type(s) to which the response applies. Blank cells indicate the authors did not describe results for that particular species in that type [6].
Species Response to fire Native
grassland
Nonnative
grassland
Grasses
grama species Reduced* 1 month after fire, then increased to near levels in unburned plots X  
Hall's panicgrass Increased* 1 month after fire, then decreased to near levels in unburned plots X  
plains lovegrass Reduced* 1 month after fire, then increased and exceeded levels on prefire plots X  
threeawn species Reduced* by fire; effect lasted through the 3 years of the study X  
weeping lovegrass Reduced* 1 month after fire, then increased & exceeded levels in unburned plots   X
Forbs
camphorweed Reduced* by fire; effect lasted through the 3 years of the study X X
leatherweed No significant response to fire X X
ragged nettlespurge Increased* 1 month to 1 year after fire, then decreased X X
redstar Increased* 1 month to 1 year after fire, then decreased X X
Rocky mountain zinnia No significant response to fire X X
spreading fanpetals Increased* 1 month to 1 year after fire, then decreased X X
wild dwarf morningglory No significant response to fire X X
wingpod purslane Increased* 1 month to 1 year after fire, then decreased X  
*Statistically significant (P<0.01) as indicated by treatment, year, or interaction term in an analysis of variance.

Shrub cover was reduced significantly (P<0.001) on burned sites dominated by native grasses in the 1st postfire growing season [3]. Burroweed density declined from approximately 60 stems/200 m to near zero in postfire year 1; it had recovered to some extent by postfire year 8, but not to prefire levels. to prefire density within 1 year [4].

Honey mesquite trees were top-killed by fire in both native and nonnative grassland. By postfire year 3, 94% had sprouted from the trunk and/or root crown [6].

Avian responses to this summer wildfire [3] reflected alterations in cover and resources. Many birds that winter in the grasslands of southeastern Arizona depend upon seed crops. Burning probably increased seed production by both native and nonnative grasses, as occurred after the 1974 wildfires described above [9]. Fire-caused reductions of litter and grass cover made the abundant seed easily available on a bare soil surface for 2 postfire years, and bird populations increased "dramatically" in both native and nonnative sites during these years [3]. Correlations suggested that species responding positively to the burn did not require grass and litter cover, whereas species responding negatively to the burn may have required shrub cover (Table 13). Seed crops depend upon adequate precipitation, and bird populations in fall of 1989, the only year of this study with rainfall substantially below average, were lower than in fall of any other year.

Table 13. Response of birds to fire and presence of nonnative lovegrasses in southeastern Arizona grassland. All differences reported in this table are statistically significant (P<0.01) [3].

Species

Sampling period Correlation with cover*
September through November May through August
Botteri's sparrow No data Not present on burned plots in postfire years 1 and 2 but more abundant on burned than unburned exotic plots in years 3-4 grass (+)
forb (-)
Cassin's sparrow No significant differences Not present on burned plots in year 1 but more abundant on burned than unburned exotic plots in years 2-4 shrub (+)
Eastern meadowlark Less abundant on burned than unburned sites in postfire year 1, more abundant on burned exotic grassland in year 2 Abundance low on burned plots in year 1, similar on burned & unburned plots in years 2-4 shrub (+)
Grasshopper sparrow No significant differences Abundance low on burned plots in years 1 and 2, similar on burned & unburned plots in years 3-4 shrub (+)
Horned lark More abundant on burned than unburned sites in year 1 in both native and exotic grassland More abundant on burned than unburned plots for 1-3 years after fire grass (-)
litter (-)
Lark sparrow No data Abundance similar on burned & unburned plots, except year 2: more abundant on burned than unburned native plots herb (+)
Mourning dove More abundant on burned than unburned sites in year 1 in native grassland More common on burned than unburned plots for 1-3 years after fire grass (-)
litter (-)
Savannah sparrow More abundant on burned than unburned sites in year 1 in both native and exotic grassland No data grass (-)
Vesper sparrow More abundant on burned than unburned sites in years 1 and 2 in both native and exotic grassland No data grass (-)
litter (-)
*Cover value with which bird abundance is significantly (P<0.01) correlated (and direction of correlation, positive or negative).

Grasshopper densities were reduced more than 60% on burned plots (both native and exotic stands), but responses of particular species varied depending on mobility and diet requirements: In the first 2 weeks after fire, charred grasshopper remains were abundant and obvious on burned plots; particularly conspicuous were dead Dactylotum variegatum, a large flightless grasshopper. This species was absent from the burned plots during 1987 and occurred in low numbers in the following 2 years. Most grass feeders were sparse in the 1st postfire year, including the Gompocerinae and Phoetaliotes nebrascensis. Melanoplus gladstoni, a forb feeder, increased in the 1st postfire year and then declined. Trimerotropis pallidipennis and other band-winged species (Oediponidae), which are usually limited to areas with substantial bare ground, outnumbered other subfamilies in the 1st month after fire; density remained relatively high 1 year later (Table 14).

Table 14. Densities of grasshoppers (number/10 m) before and after summer wildfire in an Arizona grassland. Prefire data were collected in 1984-1985. Fire occurred in July 1987. Postfire sampling occurred within 1 month after fire and 1 and 2 years later [2].
Taxon Treatment Prefire Density in postfire sampling period P (difference between years)
1 month 1  year 2 years
Gomphocerinae
     Ageneotettix deorum B 0.3 0.2 0.1 0.1 NS
U 0.3 0.3 0.1 0.2 NS
     Eritettix simplex B 1.3 0* 0.3 0.6 <0.001
U 1.3 1.1 0.4 0.5 NS**
     Parapomala wyomingensis B 0.4 0.1* 0.2 0.3 NS
U 0.4 0.6 0.3 0.2 NS
Melanoplinae
     Dactylotum bicolor variegatum B 2.6 0* 0.5 0.7 <0.001
U 1.9 1.5 0.5 0.7 <0.001
     Melanoplus desultorius B 1.0 0.1* 0.1 0.5 <0.001
U 0.7 0.8 0.7 0.5 NS
     Melanoplus gladstoni B 0.6 0.7* 0.7 0.4 NS
U 0.7 0.1 0.3 0.3 NS
     Phoetaliotes nebrascensis B 1.2 0.2* 0.8 1.5 <0.005
U 1.5 1.4 1.0 3.2 NS
Oediponidae (band-winged grasshoppers)
     Arphia pseudonietana B 0.2 0.3* 0.2 0.5 NS
U 0.3 0 0.1 0.3 <0.01
     Trimerotropis pallidepennis B 0.1 1.3* 0.6* 0.3 <0.005
U 0 0.2 0 0 NS
*Density in burned plots significantly (P<0.01) different from density in unburned plots for that year.
**NS=not statistically significant.

FIRE MANAGEMENT IMPLICATIONS:
Plant and animal responses to fire: The fire effects studies summarized here found that fire effects were generally "transitory" in semidesert grassland, oak savanna, and Madrean oak woodlands of southeastern Arizona. These fires occurred mostly while plants were dormant (February through mid-July), and they altered the abundance of many plants and animals for the 1st postfire year; a few changes persisted for 2 or more years. However, fire effects varied among life forms and species and were, in many cases, strongly influenced by precipitation patterns. The authors emphasize that even the prescribed burns conducted at the "height" of the fire season, in relatively heavy fuels (because of grazing exclusion), were "not catastrophic" and contributed to mosaic patterns on the landscape [7].

Fire frequency: After observing that most species recovered to prefire or control levels the 2nd year after spring wildfires, the authors speculate that burning at approximately 5-year intervals may have few negative effects on native flora and fauna [9].

Nonnative grasses: Fire "offers little hope" as a tool for reducing South African lovegrasses, such as weeping lovegrass, from semidesert grasslands. These species are not reduced by burning. The studies reported here did not indicate that these grasses increased substantially after fire in native-dominated grasslands [3,6]. A 2008 review by Rice and others [13] reports increases in lovegrass cover and density in semidesert and desert grasslands after fire.

Season of burning: Summer burns are likely to be more severe than winter burns and thus may have more "dramatic" effects on vegetation and wildlife [1]. This variation could be partly due to plant phenological stage. The first year after the 1984 prescribed burns, forbs decreased on in oak woodland and increased in grasslands. The woodland burn occurred 19 days prior to the grassland burn, so the grassland plots may have reached a more vulnerable phenological stage by the later burning date [7]. The research summarized here was conducted in ungrazed grasslands. Bock and Bock [1] note that grazing after fire could result in reduction of plant cover and severe erosion.

Animals: Animal responses to fire are closely related to habitat change. Early-summer fire in grassland can increase native forbs and thus benefit many bird species, especially raptors, but a mosaic of different-aged stands is needed to support diverse wildlife [1].

Responses of insects to fire are likely to be specific to the taxa present and their requirements for food and shelter. Insect density and species composition after fire are also likely to be affected by insect populations in the surrounding area that are in a mobile life stage [2].

Fire behavior measurements: Burning conditions and fire behavior were quantified for the 1984 prescribed fire, meeting the 2nd objective of this body of research (see Fire Description).


SPECIES INCLUDED IN THE SUMMARY:
This Research Project Summary contains fire effects and/or fire response information on the following species. For further information, follow the highlighted links to the FEIS reviews for those species.

Appendix

Plants

Animals

 

Common name Scientific name
   

Plants

Cactus
cactus apple Opuntia engelmannii
Forb
sagewort Artemisia spp.
leatherweed Croton pottsii var. pottsii
(Croton corymbulosus)*
Rose's ticktrefoil Desmodium rosei
spreading snakeherb Dyschoriste decumbens
spreading fleabane Erigeron divergens
wild dwarf morningglory Evolvulus arizonicus
(Evolvolus arizonica)
dwarf morningglory Evolvulus spp.
camphorweed Heterotheca submaxillaris
ragged nettlespurge Jatropha macrorhiza
tansyleaf tansyaster Machaeranthera tanacetifolia
(Aster tanacetifolius)
woolly plaintain Plantago patagonica
(Plantago purshii)
wingpod purslane Portulaca umbraticola ssp. coronata
(Portulaca coronata)
spreading fanpetals Sida abutifolia
(Sida procumbens)
toothleaf goldeneye Viguiera dentata
Rocky mountain zinnia Zinnia grandiflora
Grass
threeawn species Aristida spp.
cane bluestem Bothriochloa barbinodis
sprucetop grama Bouteloua chondrosioides
sideoats grama Bouteloua curtipendula
blue grama Bouteloua gracilis
hairy grama Bouteloua hirsuta
weeping lovegrass Eragrostis curvula var. conferta
plains lovegrass Eragrostis intermedia
Lehmann lovegrass Eragrostis lehmanniana
curlymesquite Hilaria belangeri
common wolfstail Lycurus phleoides
Hall's panicgrass Panicum hallii
vine-mesquite Panicum obtusum
Texas bluestem Schizachyrium cirratum
(Schizachyrium cirratus)
big sacaton Sporobolus wrightii
Shrub
Palmer's century plant Agave palmeri
(Agave palmeria)
yerba de pasmo Baccharis pteronioides
hairy fleabane Erigeron concinnus
burroweed Isocoma tenuisecta
shrubby false mallow Malvastrum bicuspidatum
wait-a-minute Mimosa aculeaticarpa var. biuncifera
velvetpod mimosa Mimosa dysocarpa
threadleaf ragwort Senecio flaccidus var. flaccidus
(Senecio longilobus)
soaptree yucca Yucca elata
Tree
alligator juniper Juniperus deppeana
honey mesquite Prosopis glandulosa var. glandulosa
(Prosopis juliflora)
Arizona white oak Quercus arizonica
Emory oak Quercus emoryi
Vine
bindweed Convolvulus spp.
redstar Ipomoea coccinea
(Ipomoea coccinioides)

Animals

Bird
Cooper's hawk Accipiter cooperii
Botteri's sparrow Aimophila botterii
Cassin's sparrow Aimophila cassinii
rufous-crowned sparrow Aimophila ruficeps
grasshopper sparrow Ammodramus savannarum
black-chinned hummingbird Archilochus alexandri
red-tailed hawk Buteo jamaicensis
Swainson's hawk Buteo swainsoni
lark bunting Calamospiza melanocorys
chestnut-collared longspur Calcarius ornatus
scaled quail Callipepla squamata
pine siskin Carduelis pinus
American goldfinch Carduelis tristis
house finch Carpodacus mexicanus
turkey vulture Cathartes aura
lark sparrow Chondestes grammacus
common nighthawk Chordeiles minor
northern harrier Circus cyaneus
flicker Colaptes spp.
Chihuahuan raven Corvus cryptoleucus
Montezuma quail Cyrtonyx montezumae
horned lark Eremophila alpestris
American kestrel Falco sparverius
common yellowthroat Geothlypis trichas
blue grosbeak Guiraca caerulea
barn swallow Hirundo rustica
loggerhead shrike Lanius ludovicianus
ash-throated flycatcher Myiarchus cinerascens
savannah sparrow Passerculus sandwichensis
common poorwill Phalaenoptilus nuttallii
green-tailed towhee Pipilo chlorurus
canyon towhee Pipilo fuscus
vesper sparrow Pooecetes gramineus
black phoebe Sayornis nigrican
Say's phoebe Sayornis saya
Brewer's sparrow Spizella breweri
chipping sparrow Spizella passerina
eastern meadowlark Sturnella magna
Bewick's wren Thryomanes bewickii
western kingbird Tyrannus verticalis
Cassin's kingbird Tyrannus vociferans
white-winged dove Zenaida asiatica
mourning dove Zenaida macroura
white-throated sparrow Zonotrichia albicollis
white-crowned sparrow Zonotrichia leucophry
Small mammal
northern pygmy mouse Baiomys taylori
hispid pocket mouse Chaetodipus hispidus
(Perognathus hispidus)
Merriam's kangaroo rat Dipodomys merriami
western white-throated woodrat Neotoma albigula
southern grasshopper mouse Onychomys torridus
pocket mouse Perognathus spp.
white-footed mouse Peromyscus leucopus
deer mouse Peromyscus maniculatus
western harvest mouse Reithrodontomys megalotis
hispid cotton rat Sigmodon hispidus
spotted ground squirrel Spermohilus spilosoma
Insect (grasshopper)
Scientific name
Ageneotettix deorum
Arphia pseudonietana
Dactylotum bicolor variegatum (Dactylotum veriegatum)
Eritettix simplex
Melanoplus desultorius
Melanoplus gladstoni
Parapomala wyomingensis
Phoetaliotes nebrascensis
Trimerotropis pallidepennis
*For species that have undergone scientific name changes, names in parentheses are those used in the research papers.

REFERENCES:


1. Bock, Carl E.; Bock, Jane H. 1978. Response of birds, small mammals, and vegetation to burning sacaton grasslands in southeastern Arizona. Journal of Range Management. 31(4): 296-300. [3075]
2. Bock, Carl E.; Bock, Jane H. 1991. Response of grasshoppers (Orthoptera: Acrididae) to wildfire in a southeastern Arizona grassland. The American Midland Naturalist. 125: 162-167. [15598]
3. Bock, Carl E.; Bock, Jane H. 1992. Response of birds to wildfire in native versus exotic Arizona grassland. The Southwestern Naturalist. 37(1): 73-81. [18594]
4. Bock, Carl E.; Bock, Jane H. 1997. Shrub densities in relation to fire, livestock grazing, and precipitation in an Arizona desert grassland. The Southwestern Naturalist. 42(2): 188-193. [27525]
5. Bock, Carl E.; Bock, Jane H.; Jepson, Karen L.; Ortega, Joseph C. 1986. Ecological effects of planting African lovegrasses in Arizona. National Geographic Research. 2(4): 456-463. [48085]
6. Bock, J. H.; Bock, C. E. 1992. Vegetation responses to wildfire in native versus exotic Arizona grassland. Journal of Vegetation Science. 3: 439-446. [20082]
7. Bock, Jane H.; Bock, Carl E. 1987. Fire effects following prescribed burning in two desert ecosystems. Final Report: Cooperative Agreement No. 28-03-278. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 20 p. [12321]
8. Bock, Jane H.; Bock, Carl E. 1992. Short-term reduction in plant densities following prescribed fire in an ungrazed semidesert shrub-grassland. The Southwestern Naturalist. 37(1): 49-53. [18651]
9. Bock, Jane H.; Bock, Carl E.; McKnight, J. Robert. 1976. A study of the effects of grassland fires at the research ranch in southeastern Arizona. Arizona Academy of Science. 11(3): 49-57. [4537]
10. Hann, Wendel; Havlina, Doug; Shlisky, Ayn; [and others]. 2005. Interagency fire regime condition class guidebook. Version 1.2, [Online]. In: Interagency fire regime condition class website. U.S. Department of Agriculture, Forest Service; U.S. Department of the Interior; The Nature Conservancy; Systems for Environmental Management (Producer). Variously paginated [+ appendices]. Available: http://www.frcc.gov/docs/1.2.2.2/Complete_Guidebook_V1.2.pdf [2007, May 23]. [66734]
11. LANDFIRE Rapid Assessment. 2005. Reference condition modeling manual (Version 2.1), [Online]. In: LANDFIRE. Cooperative Agreement 04-CA-11132543-189. Boulder, CO: The Nature Conservancy; U.S. Department of Agriculture, Forest Service; U.S. Department of the Interior (Producers). 72 p. Available: http://www.landfire.gov/downloadfile.php?file=RA_Modeling_Manual_v2_1.pdf [2007, May 24]. [66741]
12. LANDFIRE Rapid Assessment. 2007. Rapid assessment reference condition models, [Online]. In: LANDFIRE. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Lab; U.S. Geological Survey; The Nature Conservancy (Producers). Available: http://www.landfire.gov/models_EW.php [2008, April 18] [66533]
13. Rice, Peter M.; McPherson, Guy R.; Rew, Lisa J. 2008. Fire and nonnative invasive plants in the Interior West bioregion. In: Zouhar, Kristin; Smith, Jane Kapler; Sutherland, Steve; Brooks, Matthew L., eds. Wildland fire in ecosystems: fire and nonnative invasive plants. Gen. Tech. Rep. RMRS-GTR-42-vol. 6. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station: 141-173. [70332]

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