Suitable conditions for natural regeneration in variable retention harvesting of southern Patagonian Nothofagus pumilio forests

Abstract

Background: Variable retention (aggregated and dispersed retention) harvesting proposed for Nothofagus pumilio was designed for timber purposes and biodiversity conservation. Harvesting by opening canopy generates different microenvironments and creates contrasting conditions for seedling establishment, growth, and eco-physiology performance due to synergies (positives or negatives) with biotic and abiotic factors. This study evaluated the regeneration in different microenvironment conditions within managed stands during 5 years after harvesting. Remnant forest structure after harvesting and different microenvironments were characterized in managed stands, where 105 regeneration plots were measured (3 stands × 7 microenvironments × 5 replicas). We characterized the seedling bank, as well as growth and ecophysiology performance of the regeneration. Univariate and multivariate analyses were conducted for the comparisons. Results: Microenvironments offered different environmental conditions for natural regeneration (soil moisture and light availability). Seedling under debris and dicot plants showed better eco-physiological performance, establishment, and growth than plants growing under monocots or located in the dispersed retention without the protection of other understory plants. The most unfavorable microenvironment conditions were high canopy cover of remnant trees (inside the aggregates or close to trees in the dispersed retention) and heavily impacted areas (skidder extraction roads). Conclusions: Favorable microenvironments in the harvested areas will improve the natural recruitment, growth, and eco-physiology performance of the natural regeneration after harvesting. It is necessary to develop new silvicultural practices that decrease the unfavorable microenvironments (e.g., road density or excessive woody accumulation), to assure the success of the proposed silvicultural method.

Influencia del paisaje en las cortas de protección en bosques de Nothofagus pumilio en Tierra del Fuego, Argentina: Cambios en la estructura forestal y respuesta de la regeneración

“…Estas diferencias que no llegan a ser significativas, junto con la implementación diferencial de las empresas que aplican el método propuesto generaron diferencias en la intensidad de cosecha (17 a 32 m² ha -1 ) y una consiguiente estructura remanente (ver cuadro 2, estructura remanente). Cabe destacar que el ensamble de especies del sotobosque varía con el paisaje (Pérez Flores et al 2019, Soler et al 2019, donde su desarrollo puede generar sinergias positivas o negativas con la regeneración (Martínez Pastur et al 2013, Silva et al 2017, Toro Manríquez et al 2019. Por ejemplo, en la zona este la estructura remanente estuvo por debajo de la normativa de implementación sugerida para las cortas de protección (22 m² ha -1 ).…”

“…La regeneración natural de los bosques de lenga representa la etapa más vulnerable del ciclo del manejo, y puede verse afectada por diferentes factores, ej. ciclos de semillas, competencia con el sotobosque, o eventos de sequías o heladas extremas (Rosenfeld et al 2006, Silva et al 2017, Soler et al 2019, Toro Manríquez et al 2019. La lenga requiere de la presencia de un dosel de protección inicial que sirve a un doble propósito, por un lado, como fuente de semillas y, por el otro, de protección frente a condiciones climáticas extremas, limitando a su vez el desarrollo del sotobosque por competencia del agua del suelo y la luz incidente (López Bernal et al 2003).…”

Vegetation structure of forests over limestone and its influencing environmental factors in Samar Island Natural Park, Philippines

“…The literature has repeatedly emphasized that factors causing landscape heterogeneity are either natural or anthropogenic in nature or a combination of both (Keane 2017;Pham et al 2021). Natural factors that have been identified as causing variation in species composition, including light conditions, temperature, and relative humidity, amount of rainfall (Buot and Okitsu 1999;Miao and Jianmeng 2015;Urban 2015;Winter et al 2015;Trindade et al 2018;Dong et al 2019;Iturrate-Garcia et al 2016;Diaci et al 2020;Fan et al 2020;Nepali et al 2021), soil conditions, soil type, soil texture, soil moisture (Suzuki et al 2002;Heryati et al 2011;Davis et al 2018;Toro et al 2019), floristic composition and structure and abundance of microclimates (Richards 1996;Duchicela et al 2021), microbial composition and natural disturbances particularly, typhoons, erosion, and landslides, as well as anthropogenic disturbance history (Hong et al 1995;Muniandy et al 2009;Buot and Osumi 2011;Cardinale et al 2012;Jiang et al 2016;Tran et al 2016;Boukili et al 2017), can greatly influence the species diversity in SINP.…”

Rehabilitation of Nothofagus pumilio forests in Chilean Patagonia: can fencing and planting season effectively protect against exotic European hare browsing?

“…Therefore, it would be beneficial that individuals of N. pumilio quickly overcome 60 cm height to prevent death from browsing, or to avoid becoming deformed. Furthermore, microclimatic characteristics exert intense selective pressure on the first stages of development of the Nothofagus genus (Alberdi 1987;Martínez Pastur et al 2011;Urretavizcaya et al 2015), in addition to other physiological properties related to watering balance and resistance to environmental factors (Toro Manríquez et al 2019). For example, neighboring vegetation (nurse plants), as Berberis microphylla in South Patagonia (Bustamante et al 2020) can increase the probability that palatable plants persist despite high herbivore pressure (Miller et al 2006;Stutz et al 2015Stutz et al , 2017Löf et al 2019).…”

“…In fire degraded areas, native tree plantations may offer a wide range of benefits that include the reduction of the probability of new fire events (Veblen et al 2011), this is because grasslands and some shrublands are more combustible (Bowman et al 2009;Veblen et al 2011). Moreover, the recuperation of habitats is important for native biodiversity, soil stabilization, improvement of water provision, and landscape quality (McNamara et al 2006;Toro Manríquez et al 2019). Given that traumatic exogenous factors can compromise plant survival (Puntieri et al 2006), areas with an abundant presence of exotic herbivores need control actions that prevent or mitigate predation, e.g.…”