Identification of tree groups used by secondary cavity-nesting birds to simplify forest management in subtropical forests

SCHAAF ALEJANDRO; RUGGERA ROMAN; TALLEI EVER; VIVANCO CONSTANZA GUADALUPE; RIVERA LUIS; POLITI NATALIA

Journal of Forestry Research

Springer

Lugar: Nueva york; Año: 2019

1007-662X

In tropical and subtropical forest ecosystems,cavities formed by decay processes are a key but scarceresource for birds that nest and roost in them, which makesthem a highly sensitive group to logging. The piedmontforest of northwestern Argentina is a complex ecosystemwith 113 tree and 120 bird species. It has high loggingpressure on the few, well-conserved forest remnants,complicating the delineation of sustainable managementguidelines for each tree or bird species in a short time. Ourobjective was to reduce the complexity of subtropicalforests by grouping tree species according to the characteristicsused by secondary cavity-nesting birds (i.e. nonexcavators). In the piedmont forest, 50 plots of 0.25 hawere sampled to record cavity trees and cavity characteristics.These were then used in a cluster analysis to formtree groups. Additionally, cavities were searched to identifythe bird species using the decay-formed cavities. Atotal of 187 cavity trees, comprising 23 tree species, wererecorded, and these formed four tree groups or clusters. Werecorded 86 cavities that were used by secondary cavitynestingbird species. The four tree groups were unequallyused by secondary cavity nesters. The tree group thatincluded valuable timber species (Myroxylon peruiferum,Anadenanthera colubrina and Calycophyllum multiflorum)and had the greatest cavity availability represented 71% oftotal cavity use. Another tree group with valuable timberspecies (Cedrela balansae and Amburana cearensis),measured[73 cm DBH and[21 m tall, had cavityentrances[0.10 cm2, and contributed 14% of all cavityuse by birds. A third group had no highly economicallyvaluable tree species, and included the snag category (i.e.standing dead trees) as well as a 15% of cavity use. Thefourth tree group had a DBH�.40 cm, only one highlyeconomically valuable tree species (Cordia trichotoma),and supported no cavity use. The clustering of subtropicaltrees can reduce the complexity of these forests, henceeasing their management by focusing on those groups withtree species showing similar characteristics and providingsuitable nesting sites for secondary cavity-nesting birds.