Variable retention management influences biomass ofMisodendrumandUsneainNothofagus pumiliosouthern Patagonian forests

Abstract

Variable retention systems (retention of some existing trees in different densities along with significant elements of the original forest after logging) aim to mitigate the impact of harvesting in native temperate forests, improving biodiversity conservation in managed stands. This study evaluates the effect of variable retention harvesting on epiphytic lichens (Usnea barbata) and mistletoes (Misodendrum punctulatum) in Nothofagus pumilio forests. The abundance of these canopy-dwelling species can be estimated by measuring their litter fall. We quantified mistletoe, lichen and tree litter fall monthly for 3 years. Tree and lichen biomasses were influenced by canopy cover, being higher in primary forests than in harvested stands. However, aggregated retention showed the highest mistletoe biomass production. Furthermore, mistletoe biomass increased while lichen biomass decreased over the years after harvesting. Variable retention was useful in maintaining both lichen and mistletoe biomass after harvest, but aggregates were not enough to maintain the original level of lichen populations. Forest harvesting with variable retention generates positive (litter input) and negative (decline of host growth) effects of mistletoes and epiphytic lichens at community level, which should be evaluated during conservation and management planning.

Climate change and resilience of deciduous Nothofagus forests in central–east Chilean Patagonia over the last 3200 years

“…The mistletoe Misodendrum (a specific hemiparasite on Nothofagus species), however, is present throughout the record with relatively low values and modest increments during the last $140 years. The incidence of parasitism by Misodendrum is limited by the density of Nothofagus populations and the luminosity levels within those populations, being minimal at low densities of its host, maximal at intermediate levels (woodland, discontinuous forests), and declining towards closed-canopy forests (Soler et al, 2014). Our findings attest to the local occurrence of Nothofagus forests in the periphery of LCh and LMe, the predominance of low-luminosity levels in that forested landscape and the lack of radical changes in forest continuity during the pre-Chilean/European portion of the records.…”

Knowledge arising from long-term research of variable retention harvesting in Tierra del Fuego: where do we go from here?

“…Exotic species also increased in the harvested areas, including the colonization of the aggregate patches (Lencinas et al 2011(Lencinas et al , 2017Soler et al 2015Soler et al , 2016. Mistletoe species was another group that also increased in the harvested areas, generating a large damage in remnant trees of aggregate patches and dispersed retention (Soler et al 2014). A combination of aggregate patches and dispersed retention was the better choice to limit the exotic species introduction (e.g., Taraxacum officinale and Cerastium fontanum are indicator species of disturbance in the dispersed retention) (Lencinas et al 2017) and to protect sensitive species (e.g., Viola magellanica or Dysopsis glechomoides) (Lencinas et al 2011), improving conservation in harvested stands (Fig.…”

“…The traditional management was mainly proposed to convert primary uneven forests conformed by patches of different ages (from seedlings to 450-year-old trees) into secondary managed stands with a rotation length of 70-120 years depending of site quality and silviculture treatments (Gea et al 2004;Martínez Pastur et al 2013b). These proposals promote the total removal of the original forest structure, e.g., clear-cuttings was prescribed in 40- Lencinas et al 2005Lencinas et al , 2009Lencinas et al , 2018Soler et al 2015Soler et al , 2016Vergara and Schlatter 2006 Raptors Lencinas et al 2008bLencinas et al , 2010Lencinas et al , 2012Lencinas et al , 2014Lencinas et al , 2015Lencinas et al , 2017Simanonok et al 2011;Soler et al 2015 Lencinas et al 2008aLencinas et al , 2011Lencinas et al , 2017Soler et al 2014Soler et al , 2015Soler et al , 2016 50-m-wide strips, as well as shelterwood cuts in two-stages (first cut leaving 30 m 2 basal area and a final cut that removes the remaining trees after 10-20 years) (Martínez Pastur et al 2000). These silviculture methods were successfully applied in several temperate forests around the world, both using natural regeneration and combined with some plantation of target species (Gustafsson et al 2012;Frelich et al 2015;Donoso et al 2019).…”

“…There are several studies that investigate other groups in these forests including large mammals (e.g., Lama guanicoe), understory mosses, epiphytic lichens, mistletoes, and fungi communities of phylloplane or mycorrhizae in the natural regeneration (Table 1) (Ducid et al 2005;Lencinas et al 2008c;Soler et al 2012Soler et al , 2014Martínez Pastur et al 2016b;Hewitt et al 2018). Lama guanicoe was identified as one of the major threats for natural regeneration, due to browsing that occurred in primary unmanaged and managed forests.…”

¿Qué es un bosque nativo en la Argentina? Marco conceptual para una correcta definición de acuerdo con las políticas institucionales nacionales y el conocimiento científico disponible

“…En forma implícita se entiende que la cobertura se refiere a la arbórea, pudiendo o no descartarse de las mediciones aquellos taxones o formas de vida que no cumplen con dicho criterio, como arbustos y herbáceas de gran porte, lianas, parásitas, que pueden aumentar de forma significativa los cálculos de cobertura (e.g., Misodendrum spp. en bosques de la Patagonia) (Soler et al 2014). Por otra parte, debería quedar claro si el valor de cobertura se refiere a aquellos árboles que cumplen con los criterios de altura impuestos en las definiciones, o si también se debe incluir la de todos aquellos presentes con una menor altura (e.g., regeneración inicial de bosques en recuperación) (Martínez Pastur et al 2021).…”