Bird and vegetation diversity in Chaco forests under different cattle management practices

Birds play key roles in forest dynamics, favoring the resilience of
forests to cattle ranching. Generalist species may benefit from changes in
the vegetation structure caused by cattle grazing while specialist species
are usually negatively affected. Therefore, studying changes in taxonomic
and functional bird diversity can provide valuable information in order to
propose sustainable cattle management practices. Here, we study the
influence of different cattle management practices (Cattle Exclusion: FCE;
Continuous grazing: FCG; Rotational grazing: FRG; Seasonal grazing: FSG)
on the understory vegetation structure, and the bird taxonomic and
functional diversity in humid Chaco forests of Argentina. Forests under
grazing had an open (FCG) or semi-open (FRG and FSG) understory, whereas
FCE presented a closed understory with higher plant richness. Generalized
linear models revealed a decrease in bird richness and abundance under
most cattle management practices compared to FCE. However, FRG was most
similar to FCE in terms of vegetation structure and showed no differences
in bird richness. FCE presented the lowest values of functional diversity
while FCG and FRG showed the highest values. A fourth-corner analysis
showed that FCE was associated with insectivorous species which forage and
nest in the shrub layer, reflecting a possible loss of ecosystem services
in forests with cattle grazing.  We propose FRG as the most
appropriate cattle management option and the least detrimental to bird
assemblages. However, maintaining protected areas that exclude cattle
ranching activities will be key to striking a balance between the
conservation of most specialist species and beef production.