Fire and distance from unburned forest influence bird assemblages in Southern Andean Yungas of Northwest Argentina: a case study

Abstract

Background: Wildfires affect vegetation structure, functions, and other attributes of forest ecosystems. Among these attributes, bird assemblages may be influenced by the distance from undisturbed to fire-disturbed forests. Information about this influence is essential for designing management plans aimed at conserving birds' diversity in undisturbed forests, which contributes to their sustainability. In Northwest Argentina, timber extraction and mancaused fires threaten the sustainability of Southern Andean Yungas forests. In this region, we evaluated, in relation to a reference unburned forest, the effects of close and distant fire-disturbed patches on bird assemblages, exploring also relationships between burned and unburned forest structures on bird assemblages. On each site, we determined forest structural variables, and twice per year, from 2015 to 2017, we recorded birds seen or heard on every site, from dawn to 1000 hours, at 30 0.5 ha counting points. Results: Abundance and richness of bird species were lower in the unburned reference site than in close-and distant-burned sites; the farther the distance of burned sites to the unburned site, the less similarity in bird assemblages. Bird assemblage abundance appeared to be associated with snag height and basal area. However, bird species in mature forests were present at all sites and outnumbered those typically found in forest edges, or secondary or disturbed forests. Conclusions: Connected areas between unburned and burned forest patches provide habitat for birds living in both environments. Preventing forest fragmentation by reducing the number and size of wildfires, promoting selective timber logging, and banning post-fire snag removal will help promote suitable habitat for different bird assemblages and contribute to Yungas forests' sustainability. This study is the first step toward understanding how fire-patch distances to unburned forests may affect bird assemblages in subtropical Southern Andean Yungas forests in South America and provide a basis for comparison with other subtropical ecosystems around the world.

A review of fire effects across South American ecosystems: the role of climate and time since fire

“…The size of each black dot is proportional to its weight or contribution to the overall mean calculation. Asterisk (*) denotes a significant difference (Q-between [Q b ] statistics) among categories (* = P < 0.05) ecosystems (e.g., Barlow and Peres 2004;Fontaine and Kennedy 2012;Mestre et al 2013;Albanesi et al 2014), although there are exceptions (e.g., Fontaine and Kennedy 2012;Lee 2018;Morales et al 2020), such as the group of birds known as cavity excavators (i.e., woodpeckers [Picidae]), that take advantage of both the softness of the wood of recently burned trees (i.e., snags) for making their cavities (Schepps et al 1999;Winkler and Christie 2002;Lorenz et al 2015) and the higher amount of food (insect and other invertebrates) found in that substrate right after the fire (Murphy and Lehnhausen 1998;Nappi et al 2003).…”