Chaparral bird community responses to prescribed fire and shrub removal in three management seasons

Abstract

Chaparral, a type of shrubland common throughout the California Floristic Province, is subject to management and removal in regions where wildfire threatens human lives and property. Management practices include conducting prescribed burns outside of the historical fire season and employing mechanical fuel reduction (mastication). As the wildland–urban interface grows, particularly in coastal California, more of this ecosystem is subject to active management. To understand the ecological implications of current California chaparral fire management practices, we studied bird species composition, abundance and foraging guilds in managed and unmanaged chaparral over 5 years. Study areas were located in Mendocino County in the coast ranges of northern California. We contrast six chaparral removal or “fuels manipulation” treatments: (1) fall fire, (2) winter fire, (3) spring fire, (4) fall mastication, (5) spring mastication and (6) untreated control. Treatments and controls were implemented in plots 2 ha or larger, and replicated four times each. We find that species richness in prescribed fire treatments reaches comparable levels to controls in the first 3 years following treatment, whereas masticated units always have lower species richness. Generalized linear mixed models additionally confirm that mastication has highly negative effects on observed abundances of birds compared to controls and to prescribed fire. The season in which fuels reduction occurred was less important to species richness, although fall fire was more beneficial to bird abundance than spring or winter fire. Fire treatments in all seasons maintain the same general bird community structure as controls, while mastication results in strongly differentiated assemblages, increasing granivores while nearly excluding foliage gleaners. Synthesis and applications. We compare two California chaparral management techniques, prescribed fire and mastication, in three seasons (fall, winter and spring) in northern California, USA. We tracked chaparral bird community response in 23 experimental units for 2–5 years. We conclude that prescribed fire and mastication are not interchangeable management techniques, and that mastication negatively impacts bird communities, altering guild structure and reducing both diversity and abundance.

The effect of habitat changes along the urbanization gradient for breeding birds: an example from the Xiong’an New Area

“…Abundant tree species and substantial maturity of vegetation vertical structure could supply food and habitats for more bird guilds (Canedoli, Manenti & Padoa-Schioppa, 2018). Some studies also have found a positive influence of canopy cover (Schuetz & Schulze, 2015; Threlfall et al, 2017), although shrub cover seems to be more important for both the alpha- (Newman et al, 2018) and beta-diversities (Munoz-Pedreros et al, 2018) of bird species. The deficiency in shrub cover within our study area was probably one of the major reasons for the poor state of the total avian community.…”

Multiple trade‐offs regulate the effects of woody plant removal on biodiversity and ecosystem functions in global rangelands

“…In addition, time lags in the response of different faunal groups to habitat change may explain the insignificant effects. For example, a study in North America showed that bird community richness did not differ between the control 3 years after burning due to rapid succession in the groundstorey vegetation, which compensated for changes in the woody community (Newman, Potts, Tingley, Vaughn, & Stephens, 2018). Similar results were also found in long-term (10-30 years) studies of mammals such as deer (Ruthven III, Hellgren, & Beasom, 1994) and rats (Fulbright, Alejandro Lozano-Cavazos, Ruthven III, & Lite, 2013), which were unaffected by root-plowing due to the rapid reestablishment of the vegetation community.…”

Disturbance Ecology in the Anthropocene

“…These challenges are present in current conditions and will be more contentious in future climate conditions, where there are multiple, simultaneous goals in place for humans and biodiversity. For example, burning and clearing of California chaparral is still widely done by state and federal land management agencies with the ostensible purpose of lowering wildfire risk, which degrades the ecosystem, simultaneously lowering biodiversity and increasing the fire risk it is meant to contain (Keeley, 2002(Keeley, , 2006Newman et al, 2018a). Likewise, salvage harvesting in post-wildfire or post-hurricane forested ecosystems may be intended to reduce further risks.…”