ENVIRONMENTAL FACTORS AFFECT THE SPATIAL ARRANGEMENT OF SURVIVAL AND DAMAGE OF OUTPLANTED Nothofagus dombeyi SEEDLINGS IN THE CHILEAN ANDES Daniel P. Soto, Pablo J. Donoso, Daniel Uteau and Alejandra Zúñiga-Feest SUMMARY Mortality patterns were analyzed in a one-year old Nothofagus dombeyi plantation at mid-elevation in the Chilean Andes. Ripley´s univariate function was used to detect spatial patterns of mortality and damage (as reflected in crown dieback) of seedlings by assigning them into four categories: no crown damage, 1/3 of the crown damaged, 2/3 of the crown damaged and dead. Through correspondence analysis, variables (plant attributes, topography, weed competition, neighboring vegetation and fertilization) that could affect mortality were tested. At the end of the first growing season 67% of the seedlings survived, and by the end of the following dormant season only 37% were alive. Mortality patterns were random for seedlings with 1/3 of the crown damaged, and
lantations with native tree species in Chile are scarce, despite the fact that the Forest Service has promoted them for more than a decade. The three most widely planted trees are exotic (Pinus radiata [D. Don], Eucalyptus globulus [Labill], and E. nitens [Deane & Maiden]). Among native trees, several Nothofagus species seem to be the most promising. According to the last agricultural census there are ~4000ha of Nothofagus plantations in Chile, a rather small area that can be the result of a lack of high-quality seedlings, a poor knowledge about the plantation silviculture for these species,
clustered for all other categories. Environmental variables with the greatest influence on mortality were increasing distance to a neighboring 10m tall plantation, absence of tall vegetation cover and convex micro-topography. Results suggest that large temperature oscillations with events of freezing temperatures (defined as the reported lethal temperature for 50% of its leaves) during the growing season, and severe frost during the dormant season, were the main causes of mortality and damage. The convenience of providing seedlings with some shelter when outplanted, or with an appropriate cold-acclimation treatment to resist low freezing temperatures when outplanted in open fields in harsh cold regions of the south-central Andes is discussed.
and/or a general belief that native species have low productivity. The technology to produce high-quality bare root and containerized seedlings is available (Donoso et al., 1999; 2006; Bustos et al., 2008), and there is increasing knowledge about the silvicultural treatments to be applied to Nothofagus plantations. It was shown that low elevation Nothofagus plantations can achieve high productivity rates (Donoso et al., 1993, 1999, 2005, 2006). Unfortunately, transference and adaptation of this knowledge has been poor, and there are many questions about the fate of the plantations established at mid- and high elevations, where only few results have
been reported (Donoso et al., 1993). Mean growth rates of 16-29m3 ·ha-1 per year have been reported for some Nothofagus dombeyi ([Mirb.] (Oerst)) plantations (Donoso et al., 1993, 1999, 2006), although these have been established without special site preparation treatments (tillage, herbicide, fertilization). N. dombeyi is a pioneer tree species that colonizes sites that have been affected by large-scale disturbances such as fire, landslides or wind (Donoso, 1993; Veblen et al., 1995; Donoso et al., 2006). In general, the species has been reported as highly resistant to abiotic stress such as low temperatures, high light intensity,
KEYWORDS / Abiotic Stress / Border Effects / Freezing Temperatures / Ripley´s Function / Regeneration / Vegetation Cover / Received: 08/27/2008. Modified: 01/17/2009. Accepted: 01/21/2009.
Daniel P. Soto. Forest Engineer, Universidad Austral de Chile (UACh), Chile. Researcher, UACh, Chile. Address: Institute of Silviculture, Universidad Austral de Chile, PO Box 567, Valdivia, Chile. e-mail:
[email protected] Pablo J. Donoso. Forest Engineer, UACh, Chile. Ph.D. in Forest Resources Management, State University of New York, USA. Professor, UACh, Chile. e-mail:
[email protected] Daniel Uteau. Forest Engineer, UACh, Chile. Researcher, Institute of Silviculture, UACh, Chile. e-mail:
[email protected] Alejandra Zúñiga-Feest. Biologist and Ph.D. in Biological Sciences, Universidad de Concepción, Chile. Professor, UACh, Chile. e-mail:
[email protected]
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and drought (Alberdi, 1995; Methods Reyes-Diaz et al., 2005; Piper et al., 2007), which allow it to Characteristics of the seedlings grow in areas exposed to full and the plantation sunlight, where periods of sumThe Nothofagus dombeyi mer drought and extreme tem([Mirb.] (Oerst)) seedlings were peratures can occur (Alberdi et grown in 130cm3 polyethylene al., 1985; Weinberger, 1973). containers using composted Pinus The good adaptation of N. radiata bark as the substratum, dombeyi growing in natural and were fertilized with a slowconditions that are marginal for release (18-6-12) fertilizer (Osmomost other native tree species a Datalogger DIVER (Eijelkamp®). Black cote®; 5kg per m-3). The seed (500-1000masl), allow to expect Figure 1. Temperatures registered by white line: a 4th order polynomial model fitted to the aver- source was local, from San Pablo that plantations with this spe- line: daily average, age values (r2 = 0.593, P600masl in the Chilean Andes) for forest production of rapid growth are derived from modern volcanic ashes at the end of October of the following year species. It was established in a south-aspect (Acrudoxic hapludand), well structured, with (see Bustos et al. (2008) for further seedling open field where herbicide was applied in the a Pumice horizon over basaltic-andesitic characteristics). A spacing of ~2×2.5m was plantation lines and plants were fertilized rocks (CIREN, 1999). The texture is medium used throughout the 1ha plantation. Weeds with different doses. After one growing sea- through the entire profile, rich in thin sand were controlled by applying 4l of glyphosfate son this plantation suffered high mortality on the surface and clay in the lower profile. and 3.5l of Simazine per ha on 1m wide strips rates. One aim of the present work was to In terms of fertility the most important char- immediately after planting. study the spatial pattern of mortality and acteristics are a high water retention capacity crown damage that took place in the planta- (>250mm in 1m depth), good infiltration, Sampling tion; another aim was to explore the causes high organic matter content and total N (0.97 One growing season after for low survival and crown damage by study- ±0.07%), and a suitable C/N relation of 11.6 ing the effects of local (low) and surrounding ±0.3. However, these soils are poor in bases planting, and past the first winter and the first (tall) vegetation, micro- and macro-topogra- and P (3.5 ±0.6mg·kg-1; Donoso et al., 2007). half of the second year spring, a 2000m2 phy, fertilization and seedling morphology on The main limitations are rapid superficial (40×50m) area was sampled. In this area moisture loss, high P retention, high Al levels height, root collar diameter and the X and Y seedling mortality. (49 ±6%) due to the presence of alophan, coordinates of each one of 410 seedlings were and wind erosion (Schlatter et al., 1995). recorded. Between outplanting and sampling, Study site freezing temperatures occurred several times; just for a few hours a small The study was carried out in number of days during the first growthe Valdivian Andes of Chile ing season and even for entire days (39°35’S, 72°05’W) at 620masl in numerous times during the dormant San Pablo de Tregua, an experimenseason (Figure 1). tal forest belonging to the UniversiAt the end of the first dad Austral of Chile. The plantation growing season (May) 67% of the was established on a south facing seedlings were alive; they had slope of an abandoned open field reached an average collar diameter of with a 10m tall Nothofagus nervosa 7.3cm and an average height of 75cm. plantation and shrubby vegetation on At the beginning of the following its northern side. The region has a spring (October) only 37% of the coastal oceanic climate according to outplanted seedlings had survived; Köppen and a Mediterranean influthat is, 55% of the seedlings that ence, with short and dry summers were alive at the end of the first (Dec-Mar) and humid winters (Jungrowing season (Figure 2). Therefore, Sept). The annual precipitation, it was decided to divide seedlings mostly rainfall, ranges between 4000 into four categories related to their and 5000mm (Neira, 2005) and is associated with westerly and north- Figure 2. Spatial distribution of damaged trees in the study plot. survival and damage status: undamOpen circles shows the healthy seedlings, grey circles are seedlings erly winds (Schlatter et al., 1995). with 1/3 of the crown damaged, black circles are seedlings with 2/3 aged (the whole crown undamaged), Mean annual temperature is 11°C, of the crown damaged and crosses are dead seedlings. The upper his- slightly damaged (1/3 of its crown that of the coldest month (August) is togram corresponds to the neighboring Nothofagus nervosa plantation dead), seriously damaged (2/3 of its crown damaged) and dead. 5°C and that of the warmest one and the shrubby vegetation.
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among variables (ter Braak, 1985; Jongman et al., 1995).
Statistical analyses The X and Y coordinates of each seedling in the sampled area were incorporated into the SpPack software (Perry, 2004) to use Ripley’s K(t) function (Ripley, 1977) to represent the categories of seedling conditions. The interpretation was made according to L(d)-d against the d distance, which fits to the zero value. Therefore, the spatial pattern is grouped when L (d)-d is significantly (P0, and regular if L (d)-d is significantly
