Avifaunal responses after two decades of Polylepis forest restoration in central Argentina

Abstract

The high Andean Polylepis woodlands are home to a unique biota, including an outstanding avifauna. They are one of the most threatened mountain ecosystems worldwide; accordingly, they have been the object of the first restoration initiatives in South America. Here, we evaluated the effectiveness of 20-year Polylepis australis woodland restoration efforts to recover the woodland bird communities. We recorded bird diversity and abundance in an ongoing restoration site (with a high proportion of woodland) and in a control site, where no active restoration efforts were made (with a high proportion of grasslands and bare soil), 15 and 20 years after the start of the restoration project. We compared the avifauna of these sites with that of reference mature woodlands, using published records of the study region. At the ongoing restoration site, bird diversity increased over time, as well as abundances of species associated with P. australis, whereas those parameters remained stable at the control site. Our results are the first evidence that active restoration of P. australis entails passive restoration of the avifauna occurring in these unique upland forests.

The benefits of mountain woodland restoration

“…Schickmann et al 2012). Avian species richness and biomass are much greater in re-established upland forests in comparison to unforested areas (Barri et al 2021;Warner et al 2021), with the benefits of treeline creation extending to birds of woodland edge and open scrub (Klaus et al 2020). Livestock, reindeer, deer, and other game animals such as grouse take advantage of the shelter and nutritious forage provided by the ecotone, especially alpine willow-dominated communities (García-Gonz alez et al 2016; Denryter et al 2022).…”

“…The high diversity of fungi, plants, and invertebrates in mountain woodland subsequently provides opportunities for mycophagous, herbivorous, and insectivorous small mammals, as well as predators higher up the food chain including raptors (Scott 2000; Schickmann et al 2012). Avian species richness and biomass are much greater in re‐established upland forests in comparison to unforested areas (Barri et al 2021; Warner et al 2021), with the benefits of treeline creation extending to birds of woodland edge and open scrub (Klaus et al 2020). Livestock, reindeer, deer, and other game animals such as grouse take advantage of the shelter and nutritious forage provided by the ecotone, especially alpine willow‐dominated communities (García‐González et al 2016; Denryter et al 2022).…”

A monograph of the genus Polylepis (Rosaceae)

“…In the southern Yungas (Jujuy Province), the P. australis forests have high bird diversity, but Polylepis specialist bird species are absent, possibly because these are small patches ( Bellis et al 2014 ). However, active forest restoration measures have locally increased bird diversity and abundance over 20 years ( Barri et al 2021 ).…”

Forest restoration under leaf‐cutting ant pressure: distance from ant nests and plastic tree shelters improve sapling survival

“…Renison, personal observation). Reducing disturbances and planting Polylepis australis subsequently favor a range of organisms associated with Polyelpis forests (Becerra et al 2019;Barri et al 2021). Polylepis australis is currently used for important forest restoration efforts (https://www.…”

“…Thus, restoration efforts include fencing to exclude livestock, use of pesticides to kill leaf‐cutting ants, or use of plastic tree shelters to deter ant pruning (Renison et al 2017; D. Renison, personal observation). Reducing disturbances and planting Polylepis australis subsequently favor a range of organisms associated with Polyelpis forests (Becerra et al 2019; Barri et al 2021). Polylepis australis is currently used for important forest restoration efforts (https://www.globalforestgeneration.org/ consulted December 2021).…”