RESEARCH ARTICLE

 

Long-term monitoring of thinning for silvopastoral purposes in Nothofagus antarctica forests of Tierra del Fuego, Argentina

 

Guillermo Martínez Pastur

Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Centro Austral de Investigaciones Científicas (CADIC), Laboratorio de Recursos Agroforestales. Houssay 200, Ushuaia (9410) Tierra del Fuego, Argentina.

Rosina Soler

Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Centro Austral de Investigaciones Científicas (CADIC), Laboratorio de Recursos Agroforestales. Houssay 200, Ushuaia (9410) Tierra del Fuego, Argentina.

María V. Lencinas

Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Centro Austral de Investigaciones Científicas (CADIC), Laboratorio de Recursos Agroforestales. Houssay 200, Ushuaia (9410) Tierra del Fuego, Argentina.

Juan M. Cellini

Universidad Nacional de La Plata (UNLP), Laboratorio de Investigación de Sistemas Ecológicos y Ambientales (LISEA). Diagonal 113 n°469, La Plata (B1904DPS) Buenos Aires, Argentina.

Pablo L. Peri

Universidad Nacional de la Patagonia Austral (UNPA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Dept. Forestal, Agricultura y Manejo del Agua (INTA EEA Santa Cruz), cc 332, Río Gallegos (9400) Santa Cruz, Argentina.

 

Abstract

Aim of study: To analyse the effectiveness of thinning on tree growth, forest structure and microclimatic variables along seven years after cuttings in a secondary Nothofagus antarctica forest in Southern Patagonia.

Area of study: Five hectares of homogeneous stand of secondary forests (54º15’46” SL, 66º59’41” WL) in Tierra del Fuego, Argentina.

Material and methods: One control and two thinning levels were established, and forest structure, growth, crown dynamic and microclimate variables in long-term permanent plots were evaluated. Main comparisons were made using multiple ANOVAs.

Main results: Intensive thinning in secondary forests allowed to increase tree individual growth rates by doubling the radiation levels at the understory level that enhances the silvopastoral management. These forests showed a desirable resilience to the forest interventions and natural disturbances (e.g. heavy defoliator attack), with a rapid reaction in the canopy cover growth.

Research highlights: Monitoring of thinning for silvopastoral management must include easy and cheap measuring variables, e.g. diameter growth as a proxy for timber production objectives and hemispherical photos (crown cover and radiation) as a proxy for pasture production. Long-term monitoring allowed to identify reliable indicators that assist new sustainable management alternatives.

Additional Keywords: crown cover; leaf area index; radiation; insect plague; growth; forest structure.

Abbreviations used: BA (basal area); C (control); CC (crown cover); DBH (diameter at breast height); DIF (diffuse radiation); DIR (direct radiation); HT (heavy thinning); LT (light thinning); RLAI (relative leaf area index); SI50 (site index with a base age of 50 years); TD (tree density); TOBV (total over bark volume); TR (total radiation).

Authors' contributions: Conception and design of the plots: GMP and PLP. Acquisition, analysis and interpretation of data: GMP, RS, JMC. Statistical analysis: MVL. All authors wrote and approved the final manuscript.

Citation: Martínez Pastur, G.; Soler, R.; Lencinas, M. V.; Cellini, J. M.; Peri, P. L. (2018). Long-term monitoring of thinning for silvopastoral purposes in Nothofagus antarctica forests of Tierra del Fuego, Argentina. Forest Systems, Volume 27, Issue 1, e01S. https://doi.org/10.5424/fs/2018271-11928

Received: 21 Jun 2017. Accepted: 09 Apr 2018.

Copyright © 2018 INIA. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC-by 4.0) License.

Funding: INTA Argentina (PNFOR-1104082); CONICET Argentina (P-UE 2016).

Competing interests: The authors have declared that no competing interests exist.

Correspondence should be addressed to Guillermo Martínez Pastur: gpastur@conicet.gov.ar


 

CONTENTS

Abstract

Introduction

Material and methods

Results

Discussion

Acknowledgements

References

IntroductionTop

Nothofagus antarctica (G. Forster) Oerst. (commonly named ´ñire´) is one of the main deciduous native tree species in Tierra del Fuego. It covers more than 200,000 ha (Soler, 2012; Martínez Pastur et al., 2013), and naturally occur in different environments near drier northern areas close to the ecotone with the Fuegian steppe. These forests are mainly used for sheep and cattle production (Peri et al., 2016a). In this context, silvopastoral systems have become an economical, ecological and productive alternative for these forests (Martínez Pastur et al., 2012). These systems combine trees and natural grasslands or pastures under grazing in the same unit of land, and provide a diversification of farm income, either directly from the sale of timber and animals and/or indirectly by the provision of stock shelter and beneficial effects due to its potential on ecosystem service provisioning (Peri et al., 2016b).

For silvopastoral systems in secondary forest stands, planned thinning may reduce the time required to yield products of a desired quality, concentrate growth on selected trees, increase wood production by utilizing trees that would die due competition (self-thinning) and also improve the understorey biomass production (and consequently increase animal production) by increasing incoming radiation. In Tierra del Fuego (dominant tree height >8 m, and rainfall >350 mm/yr) intensive thinning were proposed, leaving a 30-40% of canopy cover (Peri et al., 2016a, 2016b). This remaining crown cover provides protection from desiccating strong winds, improving the microclimatic conditions for understorey plants growth and tree regeneration. However, the thinning not only provides synergies with other forest components, but also produce greater trade-offs with other ecosystem services (Gyenge et al., 2011; Martínez Pastur et al., 2017; Peri et al., 2017) and biodiversity components (Lencinas et al., 2008, 2015; Quinteros et al., 2010; Peri et al., 2016a). These changes are poorly studied in the long-term, and can be influenced by changes in the climate conditions (Kreps et al., 2012) or biological threats (e.g. attacks of defoliators) (Paritsis & Veblen, 2010; Piper et al., 2015).

To date, there is enough information to support most of the silvopastoral proposals, including forest component, natural cycles, regeneration, understorey and biodiversity (Lencinas et al., 2008, 2015; Quinteros et al., 2010; Gyenge et al., 2011; Ivancich et al., 2011, 2014; Soler, 2012; Soler et al., 2013; Bahamonde et al., 2013, 2015; Martínez Pastur et al., 2013; Gargaglione et al., 2014; Echevarría et al., 2014; Gönc et al., 2015; Peri et al., 2016a,b, 2017). However long-term results along the forest cycle, and its resilience deserve special attention. These long-term data can allowed to design new management alternatives (Martínez Pastur et al., 2016; Peri et al., 2016c). In this sense, long-term plots are essential to determine the economic feasibility of the intermediate treatments, define baselines and impacts of different silvicultural treatments and provide monitoring methodologies (Peri et al., 2016b). For this, the objective of the present work was to analyse the effectiveness of the different levels of thinning on tree growth, remnant forest structure and microclimatic variables along seven years after the cuttings in a secondary Nothofagus antarctica forests in Tierra del Fuego, Argentina.

Material and methodsTop

Study site and long-term plots

The study was carried out in San Pablo Ranch located in Tierra del Fuego province (Argentina). Almost half of the ranch area is covered by native N. antarctica forests with different degree of previous human impacts, e.g. clear-cuts of old-growth stands which derived in secondary young forests. The rancher manages the forests following silvopastoral system proposals (e.g. see Martínez Pastur et al., 2013; Peri et al., 2016a,b) that includes thinning to promote understory development (e.g. pastures and native forage species). In the framework of PEBANPA network (Peri et al., 2016c), an experimental assay was established in early winter of 2009 in a 5-ha homogeneous stand of secondary forests (54º15’46” SL, 66º59’41” WL). This area was divided into four contiguous areas, two of them were left as control treatments (C) (1.0 ha each) and the other two were thinned at two intensities: one heavy thinning (HT) with a remnant basal area (BA) of 12 m²/ha (1.5 ha) and one light thinning (LT) where the remnant BA was 18 m²/ha (1.5 ha). The stand belongs to a middle site quality (mean dominant height of 10.1 m and 48 years old) with a SI50 (site index with a base age of 50 years) of 10-12 m (Ivancich et al., 2011).

Forest structure monitoring

Forest structure were monitored in 15 permanent plots (5 per treatment) located in the control and thinned stands (n = 5 per treatment) with different area according the final tree density: 154 m² in C, 314 m² in LT and 452 m² in HT. Prior to the cuts the original structure (base line) was measured (winter 2009) including diameter at breast height (DBH) of all trees, health characterization and crown classes. After the cuts, the remnant trees were identified with number tags and snails, and survival and DBH were measured annually at the end of each season (2010-2016). After cutting total over bark volume (TOBV) was measured in 48 trees belonging to different diameter (4 to 35 cm) and crown classes (suppressed to dominant): diameter every 1 m from the base to the top, including branches up to 1 cm. Smalian formula was used to integrate the volume of each tree. Non-linear regression technique was used to obtain the TOBV equation (r² = 0.838, average error of estimation = 0.0027 m3, and average absolute error = 0.0164 m3).

TOBV (m3) = 0.000113621 × DBH2.43623 (cm)

Crown cover and microclimate monitoring

The centre of each permanent plot was marked with an iron stick, and there hemispherical photographs of forest canopy were taken at 1 m above the ground level with an 8 mm fish-eye lens (Sigma, Japan) mounted on a 35 mm full-frame digital camera (Nikon, Japan) with a tripod levelling head. Each photograph was orientated with the upper edge towards the magnetic north. Photographs were taken when there was no direct sunshine (Roxburgh & Kelly, 1995). Gap Light Analyzer software v.2.0 (Frazer et al., 2001) was used to calculate: (i) crown cover (CC), (ii) relative leaf area index (RLAI) defined as the effective amount of leaf surface area per unit ground area integrated over the zenith angles 0° to 60° (Stenberg et al., 1994), and (iii) total radiation (TR) at the understory level as the amount of direct (DIR) and diffuse (DIF) radiation transmitted through the canopy along the growing season (October to March), expressed as the percentage of the radiation received above the forest canopy. The parameters employed for the modelling were described by Martínez Pastur et al. (2011). Photographs were taken in summer (end January) during the maximum expansion of the tree leaves (2010-2016). Finally, nine data loggers (3 per treatment) were located at 1 m above the ground level for 7 months during the first year to assess the effect of the thinning on: air temperature (°C), air humidity (%) and soil temperature (°C) at 30 cm depth.

Statistical analyses

Multiple ANOVAs were conducted to compare tree growth variables, analysing growth in diameter at breast height (G-DBH), growth in basal area (G-BA), growth in total over bark volume (G-TOBV) and ratio of G-TOBV and G-BA (G-ratio) using thinning treatments (C, LT, HT) and seasons (09/10 to 15/16) as main factors. Data were log-transformed when normality assumption was not achieved. Tukey test was applied to separate the means at a significance level of p < 0.05. Beside this, Kruskal-Wallis were conducted to compare forest structure, crown cover dynamic and microclimate variables, analysing (i) tree density (TD), DBH, BA and TOBV of the original structure using thinning treatments (C, LT, HT) and years (2009-2016) as comparison factors; and (ii) CC, RLAI, DIF, DIR, and TR, using thinning treatments (C, LT, HT) and years (2010-2016) as comparison factors. Box-and-whisker plot analyses was used to separate the means. For all the test, we used Statgraphics Centurion XVI software (Statpoint Technologies, USA).

ResultsTop

Original forest structure belongs to a typical secondary forests with 71-82% BA of dominant and co-dominant trees, with different degrees of health (28% BA of healthy trees, 51% BA of trees with minor damages and 21% BA of unhealthy trees). Trees were mostly affected by fungi and Misodendrum sp. attack. The measured forest parameters did not present significant differences (data not shown) prior thinning among the areas selected for each treatment: TD=2183-2793 trees/ha, DBH=12.4-14.3 cm, BA=34.0-38.7 m²/ha, and TOBV=163.0-190.5 m3/ha. After thinning, these variables presented significant differences over time due to the growth of remnant trees (Fig. 1). TD, BA and TOBV were significantly reduced from C > LT > HT, while DBH increased from C < LT < HT, and only DBH presented differences among the years. LT reduced in 75% TD, but only reduced 45% BA and 36% TOBV, while HT reduced in 87% TD, and 63% BA and 56% TOBV. Beside this, average DBH of the thinned stand increased 48% in LT and 73% in HT.

Figure 1. Kruskal-Wallis comparisons considering treatments (C: control, LT: light thinning, HT: heavy thinning) and years (2009 to 2016) as factors, and tree density (TD), diameter at breast height (DBH), basal area (BA) and total over bark volume (TOBV) as variables. Different letters indicate differences by box-and-whisker plot analyses. Capital letters indicates differences among years for each treatment, and lowercase letters indicates differences among treatments for each year.

These changes in the forest structure influenced tree growth at individual and the stand levels (Table 1). An increase in the G-DBH (33% and 71% compared to C in LT and HT, respectively), and a decrease in G-BA and G-TOBV were observed in the control compared with thinned treatments (-12% and -8% for LT, and -38% and -32% for HT for G-BA and G-TOVB compared to C, respectively) (Fig. 2). The ratio between G-TOBV and G-BA greatly increased in thinned treatments compared with the control (70% in LT and 90% in HT). There was a great variation in growth over time, where the highest values occurred in the second year after thinning, and decreased in the following years to date. These growth rates influenced the class diameter distribution of the managed stands compared to the control (Fig. 3) where the individual size increased with the thinning intensity. Beside this, the recorded heavy attack of one defoliator, Ormiscodes amphimone (Fabricius), during the growing season of 2012-2013 greatly impacted on tree growth by decreasing the main studied variables (-18% G-DBH, -44% G-BA, -34% GTOBV, and -39% for G-ratio compared with the average of previous and following seasons). The impact of the defoliation mainly impacted HT (Fig. 1). However, other variables recovered the expected values in the following growing seasons.

Table 1. Multiple ANOVAs considering treatments (C: control, LT: light thinning, HT: heavy thinning) and seasons as main factors, and growth in diameter at breast height (G-DBH), growth in basal area (G-BA), growth in total over bark volume (G-TOBV) and ratio of G-TOBV and G-BA (G-ratio) as variables.

Figure 2. Growth in diameter at breast height (G-DBH), growth in basal area (G-BA), growth in total over bark volume (G-TOBV) and ratio of G-TOBV and G-BA (G-ratio) along the growth seasons (2009/2010-2015/2016) and treatments (C: control, LT: light thinning, HT: heavy thinning).

Figure 3. Class diameter distribution for the different treatments (C: control, LT: light thinning, HT: heavy thinning) after 6 years after the thinnings (year 2016).

After thinning, the crown cover and radiation presented significant differences due to the changes in the forest structure and tree growth (Figs. 4 and 5). CC and RLAI were significantly reduced from C > LT > HT, while radiation (DIR, DIF and TR) increased C < LT < HT (Fig. 4). LT reduced in 11% CC and 25% RLAI, increasing near 40% the radiation values. On the other hand, HT reduced in 27% CC and 57% RLAI, increasing more than 100% the radiation values inside the forests. Along the years, crown development increased the canopy cover and the RLAI, decreasing 25% of the radiation levels measured just after the thinning. These variables also were impacted by the attack of the defoliator obtaining -8% CC, -15% RLAI, and 12-19% radiation levels compared with the average of previous and following years (Fig. 6). The crown dynamic and radiation recovered the expected values in the following growing seasons as well as the growth variables.

Figure 4. Kruskal-Wallis comparisons considering treatments (C: control, LT: light thinning, HT: heavy thinning) and years (2009 to 2016) as factors, and crown cover (CC), relative leaf area index (RLAI), transmitted direct radiation (DIR), transmitted diffuse radiation (DIF) and transmitted total radiation (TR) as variables.

Figure 5. Crown cover for the different treatments (left: control, centre: light thinning, right: heavy thinning) at the year 2010 (up) and 2016 (bottom).

Figure 6. Crown cover (CC), relative leaf area index (RLAI) and transmitted total radiation (TR) along the years (2010-2016) and treatments (C: control, LT: light thinning, HT: heavy thinning).

These changes in the forest structure and the crown variables influenced on other micro-climatic variables (Fig. 7). Air temperature was the less influenced, however, it was observed that C treatment mitigate the extreme values during summer (low average values) and winter (high average values). Soil temperature and air humidity did not greatly changed between the C and LT treatments, while HT presented differences of -2°C and 15% compared with C, respectively.

Figure 7. Microclimate data considering months and treatments (C: control, LT: light thinning, HT: heavy thinning). Differences between the thinning treatments and the control are also presented.

DiscussionTop

Nothofagus antarctica forests are characterised by a lower timber values in Tierra del Fuego forests due to over-mature forest structures growing in low site quality (Ivancich et al., 2011, 2014; Peri et al., 2016b), but greatest amount of understory biomass due to lower canopy closeness is produced (Lencinas et al., 2008; Soler, 2012). These characteristics determine that these forests were mainly used for sheep and cattle breeding. However, human activities during the last 100 years greatly changed the forest structure of many over-mature stands. Clear-cuts and human fires convert large areas in over-stocked secondary forests with low amount of understory biomass (Soler, 2012; Soler et al., 2013). These forest structures must be managed to recover the desired characteristics for silvopastoral management that appears as the most attractive economical alternative through thinning practices/intervention (Peri et al., 2016a).

Thinning objectives varied with the silvicultural management defined for each forest type, e.g. in southern Patagonia thinning had been applied in N. pumilio and N. betuloides to increase specifically the quantity and quality of timber-wood (Martínez Pastur et al., 2001, 2002; Peri et al., 2002, 2013). However, thinning for silvopastoral management must consider multiple objectives, e.g. in N. antarctica forests the interventions try to improve both the quality and quantity of timber, and at the same time enhance pastures biomass by increasing the radiation levels (Martínez Pastur et al., 2013; Peri et al., 2016a,b).

The proposed thinning levels for the studied secondary forests can be considered very intensive (75-87% tree removal) compared with other thinning proposals in the region (Martínez Pastur et al., 2001, 2002; Peri et al., 2002, 2013), because the need of increase the radiation levels into the forests (50-100%). Also, at these latitudes, the thinning allows rainfall to reach the forest floor by reducing the canopy interception (Caldentey et al., 2005). These two variables (light and soil moisture availability) were the most influential ones over understory biomass growth (Lencinas et al., 2008; Quinteros et al., 2010; Soler, 2012; Gönc et al., 2015).

Canopy of N. antarctica quickly reacted to the cuttings by recovering the original levels in the light thinning treatment 4 years after cutting, as well as it was observed for other Nothofagus species (Martínez Pastur et al., 2002; Peri et al., 2013). Heavy thinning favoured greatest diametric growth (tree variable) with the best G-ratio (stand variable) which maximized the performance of individual trees and increased by 100% the radiation levels. Considering these individual tree growth rates, the timber volume can be increased in the stand (Ivancich et al., 2014) and the radiation levels is enough to develop good-quality pastures for cattle breading (Peri et al., 2016b). For this, heavy thinning levels offered the best combination for silvopastoral management purposes, maintaining for longer periods the benefits of the silvicultural interventions.

The value of resilience in forest ecosystem management has been widely accepted (Yan et al., 2011). Ecosystem resilience is one of the key target for sustainable management. This represents the ability of one ecosystem to absorb impacts before a threshold is reached where the ecosystem changes into a different state (ecological point of view), or the capacity of one ecosystem to return to its more-or-less exact pre-disturbance state (engineering point of view) (Gunderson, 2000; Carpenter et al., 2001). Nothofagus in general and particularly N. antarctica forests were described as resilient ecosystem considering a wide range of natural and anthropogenic disturbances (e.g. Frangi et al., 2015; Peri et al., 2017). The studied forests were converted to pastures in the 50s of the last century by clear-cuts, but abundantly regenerated in the following years resulting in a secondary forests with complete crown cover. After thinning, trees quickly reacted in diameter and crown development. This determines frequent interventions to maintain the open degree of the canopy (e.g. LT recover the canopy cover almost completely to date, while HT still present an appropriate openness degree). This reaction is desirable in terms of timber production, but increase the costs of interventions for silvopastoral purposes.

The recover after the caterpillar attack which significantly reduced the alive canopy is another good example of resilience of these forests, where after disturbance, the values arrived to the expected pre-disturbance levels. This kind of attacks can be related with a loss of growth, accelerating the die-back processes and mortality, related to C and N storage (Piper et al., 2015). Beside this, it is also interesting to observe (Fig. 4) that the attack was higher in the more intensive thinning, producing greater losses and lower recovery rate in the following season compared to LT. This can be explained by the changes in the microclimatic conditions (e.g. increase of temperature) favouring higher consumption rate by the Ormiscodes amphimone larvae (Paritsis & Veblen, 2010). These authors also relate an increase in the population of defoliators due to foliage quality, and the higher thinning can produce and increase in the quality of the tree leaves due to major availability of limiting resources (e.g. soil nutrients, soil moisture and light) (Soler et al., 2011).

Tree diameter was the most useful variable for monitoring growth in forests with timber production purposes (e.g. Martínez Pastur et al., 2001, 2002; Peri et al., 2002, 2013). However, in forests managed for silvopastoral purposes, the pastures allowance must be also monitored. This variable can be estimated using the tree crown cover as a proxy (Peri et al., 2006a,b). Here we tested the use of hemispherical photographs for monitoring crown and radiation variables using simple models and available software (e.g. Martínez Pastur et al., 2011). This methodology allowed to measured variation in these variables through the years, which greatly influenced on several ecological processes related to productivity in agroforestry systems (e.g. moisture availability, nutrient cycles, decomposition, regeneration) (Soler, 2012; Bahamonde et al., 2013, 2015; Martínez Pastur et al., 2013; Peri et al., 2016a). Finally, these monitoring also allowed us to detect changes in the control treatment (e.g. increasing crown cover), which can be related to the natural development of the stand (e.g. Ivancich et al., 2011, 2014) or climate change effects (Kreps et al., 2012) which occurring in the last decades in Tierra del Fuego (Ivancich et al., 2012).

In summary, intensive thinning in Nothofagus antarctica secondary forests increased individual tree growth rates and doubling the radiation levels at the understory level, achieving the main objectives of the silvopastoral management. These forests exhibit a desirable resilience to forestry interventions and natural disturbances (e.g. heavy defoliator attack), with a quickly reaction in the canopy cover growth. Monitoring of thinning for silvopastoral purposes must include easy and cheap measuring variables, e.g. diameter growth as a proxy for timber production objectives and hemispherical photos (crown cover and radiation) as a proxy for pasture production. Long-term monitoring allowed identifying reliable indicators, which can be used to develop new sustainable management alternatives.

AcknowledgementsTop

To Benjamin Roberts and Juan Apollinaire of San Pablo Ranch (Tierra del Fuego) for their valuable collaboration in the establishment and monitoring of the long term plots in their land.


ReferencesTop

Bahamonde HA, Peri PL, Alvarez R, Barneix A, Moretto A, Martínez Pastur G, 2013. Silvopastoral use of Nothofagus antarctica in Southern Patagonian forests, influence over net nitrogen soil mineralization. Agrofor Syst 87: 259-271. https://doi.org/10.1007/s10457-012-9541-5

Bahamonde HA, Peri PL, Martínez Pastur G, Monelos L, 2015. Litterfall and nutrients return in Nothofagus antarctica forests growing in a site quality gradient with different management uses in Southern Patagonia. Eur J For Res 134: 113-124. https://doi.org/10.1007/s10342-014-0837-z

Caldentey J, Ibarra M, Promis A, 2005. Microclimatic variations in a Nothofagus pumilio forest caused by shelterwood systems: Results of seven years of observations. Int For Rev 7: 46-50.

Carpenter SR, Walker B, Anderies J, Abel N, 2001. From metaphor to measurement: Resilience of what to what? J Ecosyst 4: 765-781. https://doi.org/10.1007/s10021-001-0045-9

Echevarría DC, Von Müller AR, Hansen NE, Bava JO, 2014. Efecto del ramoneo bovino en renovales de Nothofagus antarctica en Chubut, Argentina, en relación con la carga ganadera y la altura de la plantas. Bosque 35 (3): 357-368. https://doi.org/10.4067/S0717-92002014000300010

Frangi JL, Pérez C, Martiarena R, Pinazo M, Martínez Pastur G, Brown A, Peri PL, Ceballos DS, 2015. Aspectos ecológicos y ambientales de los bosques nativos y plantaciones forestales en la Argentina: Una visión panorámica y conceptual. In: El deterioro del suelo y el ambiente en Argentina; Casas RR (Ed), pp: 365-432. Ed. FECIC, Buenos Aires.

Frazer GW, Fournier RA, Trofymow JA, Gall RJ, 2001. A comparison of digital and film fisheye photography for analysis of forest canopy structure and gap light transmission. Agric For Meteorol 109: 249-263. https://doi.org/10.1016/S0168-1923(01)00274-X

Gargaglione V, Peri PL, Rubio G, 2014. Tree-grass interactions for N in Nothofagus antarctica silvopastoral systems: Evidence of facilitation from trees to underneath grasses. Agrofor Syst 88 (5): 779-790. https://doi.org/10.1007/s10457-014-9724-3

Gönc RL, Casaux RJ, Szulkin-Dolhatz D, 2015. Efectos de los disturbios generados por diferentes estrategias de manejo sobre los estratos vegetales de bosques de Nothofagus antarctica de Chubut, Argentina. Ecol Austr 25 (3): 231-241.

Gunderson LH, 2000. Ecological resilience: In theory and application. Ann Rev Ecol System 31: 425-439. https://doi.org/10.1146/annurev.ecolsys.31.1.425

Gyenge J, Fernández ME, Sarasola M, Schlichter T, 2011. Stand density and drought interaction on water relations of Nothofagus antarctica: Contribution of forest management to climate change adaptability. Trees 25 (6): 1111-1120. https://doi.org/10.1007/s00468-011-0586-2

Ivancich H, Martínez Pastur G, Peri PL, 2011. Modelos forzados y no forzados para el cálculo del índice de sitio en bosques de Nothofagus antarctica. Bosque 32 (2): 135-145. https://doi.org/10.4067/S0717-92002011000200004

Ivancich H, Martínez Pastur G, Roig FA, Barrera M, Pulido F, 2012. Changes in height growth patterns in the upper tree-line forests of Tierra del Fuego in relation to climate change. Bosque 33 (3): 267-270. https://doi.org/10.4067/S0717-92002012000300006

Ivancich H, Martínez Pastur G, Lencinas MV, Cellini JM, Peri PL, 2014. Proposals for Nothofagus antarctica diameter growth estimation: Simple vs. global models. J For Sci 60 (8): 307-317. https://doi.org/10.17221/22/2014-JFS

Kreps G, Martínez Pastur G, Peri PL, 2012. Cambio climático en Patagonia Sur: Escenarios futuros en el manejo de los recursos naturales. Ed. INTA, Buenos Aires, 100 pp.

Lencinas MV, Martínez Pastur G, Rivero P, Busso C, 2008. Conservation value of timber quality vs. associated non-timber quality stands for understory diversity in Nothofagus forests. Biodiv Conserv 17: 2579-2597. https://doi.org/10.1007/s10531-008-9323-6

Lencinas MV, Kreps G, Soler R, Peri PL, Porta A, Ramírez M, Martínez Pastur G, 2015. Neochelanops michaelseni (Pseudoscorpiones: Chernetidae) as a potential bioindicator in managed and unmanaged Nothofagus forests of Tierra del Fuego. J Arach 43 (3): 406-412. https://doi.org/10.1636/0161-8202-43.3.406

Martínez Pastur G, Cellini JM, Lencinas MV, Vukasovic R, Vicente R, Bertolami F, Giunchi J, 2001. Modificación del crecimiento y de la calidad de fustes en un raleo fuerte de un rodal en fase de crecimiento óptimo inicial de Nothofagus pumilio (Poepp. et Endl.) Krasser. Ecol Aust 11: 95-104.

Martínez Pastur G, Cellini JM, Lencinas MV, Vukasovic R, Peri PL, Donoso S, 2002. Response of Nothofagus betuloides (Mirb.) Oersted to different thinning intensities in Tierra del Fuego (Argentina). Interciencia 27 (12): 679-685.

Martínez Pastur G, Peri PL, Cellini JM, Lencinas MV, Barrera M, Ivancich H, 2011. Canopy structure analysis for estimating forest regeneration dynamics and growth in Nothofagus pumilio forests. Ann For Sci 68: 587-594. https://doi.org/10.1007/s13595-011-0059-1

Martínez Pastur G, Andrieu E, Iverson LR, Peri PL, 2012. Agroforestry landscapes and global change: Landscape ecology tools for management and conservation. Agrofor Syst 85 (3): 315-318. https://doi.org/10.1007/s10457-012-9496-6

Martínez Pastur G, Peri PL, Lencinas MV, Cellini JM, Barrera M, Soler R, Ivancich H, Mestre L, Moretto A, Anderson CB, Pulido F, 2013. La producción forestal y la conservación de la biodiversidad en los bosques de Nothofagus en Tierra del Fuego y Patagonia Sur. In: Silvicultura en bosques nativos: Avances en la investigación en Chile, Argentina y Nueva Zelanda; Donoso P, Promis A (Eds). Universidad Austral de Chile, pp: 155-179. Valdivia, Chile.

Martínez Pastur G, Peri PL, Lencinas MV, Soler R, Bahamonde HA, Valenzuela A, Cabello JL, Anderson CB, 2016. Investigación socio-ecológica a largo plazo en la Patagonia Austral: Estrategias interdisciplinarias para lograr la conservación de los recursos naturales a través de un manejo sustentable bajo escenarios de cambio global. Ecosistemas 25 (1): 49-57. https://doi.org/10.7818/ECOS.2016.25-1.06

Martínez Pastur G, Peri PL, Huertas Herrera A, Schindler S, Díaz Delgado R, Lencinas MV, Soler R, 2017. Linking potential biodiversity and three ecosystem services in silvopastoral managed forests landscapes of Tierra del Fuego, Argentina. Int J Biodiv Sci Ecosyst Serv Manage 13 (2): 1-11. https://doi.org/10.1080/21513732.2016.1260056

Paritsis J, Veblen TT, 2010. Temperature and foliage quality affect performance of the outbreak defoliator Ormiscodes amphimone (F.) (Lepidoptera: saturniidae) in Northwestern Patagonia, Argentina. Rev Chil Hist Nat 83 (4): 593-603. https://doi.org/10.4067/S0716-078X2010000400012

Peri PL, Martínez Pastur G, Vukasovic R, Díaz B, Lencinas MV, Cellini JM, 2002. Thinning schedules to reduce risk of windthrow in Nothofagus pumilio forests of Patagonia, Argentina. Bosque 23 (2): 19-28. https://doi.org/10.4067/S0717-92002002000200003

Peri PL, Martínez Pastur G, Monelos L, 2013. Natural dynamics and thinning response of young lenga (Nothofagus pumilio) trees in secondary forests of Southern Patagonia. Bosque 34 (3): 273-279. https://doi.org/10.4067/S0717-92002013000300003

Peri PL, Hansen N, Bahamonde HA, Lencinas MV, Von Müller AR, Ormaechea S, Gargaglione V, Soler R, Tejera L, Lloyd CE, Martínez Pastur G, 2016a. Silvopastoral systems under native forest in Patagonia, Argentina. In: Silvopastoral systems in southern South America; Peri PL, Dube F, Varella A (Eds.). Springer. Series: Advances in Agroforestry 11, Chapter 6, pp:117-168. NY.

Peri PL, Bahamonde HA, Lencinas MV, Gargaglione V, Soler R, Ormaechea S, Martínez Pastur G, 2016b. A review of silvopastoral systems in native forests of Nothofagus antarctica in southern Patagonia, Argentina. Agrofor Syst 90: 933-960. https://doi.org/10.1007/s10457-016-9890-6

Peri PL, Lencinas MV, Bousson J, Lasagno R, Soler R, Bahamonde HA, Martínez Pastur G, 2016c. Biodiversity and ecological long-term plots in Southern Patagonia to support sustainable land management: The case of PEBANPA network. J Nat Conserv 34: 51-64. https://doi.org/10.1016/j.jnc.2016.09.003

Peri PL, López D, Rusch V, Rusch G, Rosas YM, Martinez Pastur G, 2017. State and transition model approach in native forests of Southern Patagonia (Argentina): Linking ecosystemic services, thresholds and resilience. Int J Biodiv Sci Ecosyst Serv Manag 13(2): 105-118. https://doi.org/10.1080/21513732.2017.1304995

Piper FI, Gundale MJ, Fajardo A, 2015. Extreme defoliation reduces tree growth but not C and N storage in a winter-deciduous species. Ann Bot 115 (7): 1093-1103. https://doi.org/10.1093/aob/mcv038

Quinteros P, Hansen N, Kutschker A, 2010. Composición y diversidad del sotobosque de ñire (Nothofagus antarctica) en función de la estructura del bosque. Ecologia Austral 20 (3): 225-234.

Roxburgh JR, Kelly D, 1995. Uses and limitations of hemispherical photography for estimating forest light environments. N Z J Ecol 19 (2): 213-217.

Soler R, G Martínez Pastur, MV Lencinas, A Moretto, PL Peri, 2011. Above- and below-ground nutrient tissue concentration and leaf pigment changes in Patagonian woody seedlings grown under light and soil moisture gradients. J Plant Nutr 34: 2222-2236. https://doi.org/10.1080/01904167.2011.618580

Soler R, 2012. Doctoral thesis. Regeneración natural de Nothofagus antarctica en bosques primarios, secundarios y bajo uso silvopastoril. Universidad Nacional de Córdoba, Córdoba, Argentina. 135 pp.

Soler R, Martínez Pastur G, Peri PL, Lencinas MV, Pulido F, 2013. Are silvopastoral systems compatible with forest regeneration? An integrative approach in southern Patagonia. Agrofor Syst 87 (6): 1213-1227. https://doi.org/10.1007/s10457-013-9631-z

Stenberg P, Linder S, Smolander H, Flower-Ellis J, 1994. Performance of the LAI-2000 plant canopy analyzer in estimating leaf area index of some Scots pine stands. Tree Physiol 14: 981-995. https://doi.org/10.1093/treephys/14.7-8-9.981

Yan H, Zhan J, Zhang T, 2011. Resilience of forest ecosystems and its influencing factors. Proc Environ Sci 10: 2201-2206. https://doi.org/10.1016/j.proenv.2011.09.345




 

 

 



Webpage: www.inia.es/Forestsystems