Fire Effects Information System (FEIS)

FEIS Home Page

Research Project Summary: Effects of understory fire on cavity-nesting birds in Arizona pine forests

• RESEARCH PROJECT SUMMARY CITATION
• SPECIES INCLUDED IN THE SUMMARY
• STUDY LOCATION
• SITE DESCRIPTION
• PREFIRE PLANT COMMUNITY
• PLANT PHENOLOGY
• FIRE SEASON/SEVERITY CLASSIFICATION
• FIRE DESCRIPTION
• FIRE EFFECTS ON PLANT COMMUNITY
• FIRE MANAGEMENT IMPLICATIONS
• REFERENCES

Horton, Scott P.; Mannan, R. William. 1988. Effects of prescribed fire on snags and cavity-nesting birds in southeastern Arizona pine forests. Wildlife Society Bulletin. 16: 37-44 [2].

Small snags in unburned stands showed little evidence of decay and contained no cavities. Most large snags in unburned stands showed some evidence of decay:

Densities of cavity-nesting birds before treatment are shown below with posttreatment data (see Fire Effects on Cavity-nesting Birds). In unburned stands, cavity nesters generally preferred snags >50 cm DBH in decay classes II or III, although nest-tree preferences varied for the 8 most common species:

In the 65 years prior to this study, no wildfires in the study area were larger than 2 ha. The authors note that, prior to the 20th century, fires were probably frequent and extensive in southwestern ponderosa pine forests (including Arizona pine), burning every 5 to 12 years [2]. A recent synthesis of fire regime information for southwestern ponderosa pine forests [4] provides this description of the historical fire regime:

Research Objectives: This study compared 3 characteristics of Arizona pine forests before and after prescribed fire: number and characteristics of Arizona pine snags, availability of snags used by cavity-nesting birds, and breeding populations of cavity-nesting birds.

Fires were broadcast underburns that backed downslope and into the wind. Two stands were burned in mid-November 1984; the third was burned in early May 1985. Burns were conducted within the prescribed weather conditions listed below, and fire behavior generally stayed within the prescribed limits.

FIRE EFFECTS ON SNAGS:
Fire effects on Arizona pine snags were measured the first summer after prescribed burning (summer 1985). Treatments reduced both large and small snags by about 50%. Density of the kind of snags generally preferred by cavity nesters (>50 cm DBH in decay classes II or III) were reduced from 1.5 to 1.0 snags/ha. Snags with greater decay were significantly (P<0.001) more vulnerable to fire damage; 73% of snags in decay class IV burned down or were reduced more than 50% in height, in comparison with less than 20% of snags in decay classes II and VI. Snags >30 cm DBH were more likely to burn than smaller snags, probably because larger snags had more advanced decay. Snags with large amounts of undecayed twigs, branches, and sloughed bark at the base ignited more easily than those with less fuel or mostly decayed fuel at the base. Few large snags were created by the burns, but small snags increased 20-fold:

FIRE EFFECTS ON CAVITY-NESTING BIRDS:
Cavity-nesting birds were surveyed the first breeding season after prescribed burning (May-July 1985). Only 3 species showed significant (P<0.10) differences in density between burned and unburned sites (which included both control sites and preburn treatment sites): Mountain chickadee density was greater, and northern flicker and violet-green swallow  densities decreased. The authors attributed the differences to changes in prey populations, shifts in foraging areas after burning, or both.

FIRE MANAGEMENT IMPLICATIONS:
Management objectives for the burns, to improve regeneration and growth of Arizona pines and reduce woody fuels, were met.

The authors recommend that protection of large snags (by constructing fuel breaks around the trees) be considered before conducting prescribed underburns in forests where large snags have been reduced by logging. It is most important to protect snags >50 cm DBH in decay classes II and III, which can provide nest sites for most cavity-nesting birds, and snags in decay class I, which may provide nest sites in the future.

REFERENCES:

1. 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]

2. Horton, Scott P.; Mannan, R. William. 1988. Effects of prescribed fire on snags and cavity-nesting birds in southeastern Arizona pine forests. Wildlife Society Bulletin. 16: 37-44. [5549]

3. 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]

4. LANDFIRE Rapid Assessment. 2007. Rapid assessment reference condition models. 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 [66533]