Effects of spacing on early growth rate and carbon sequestration in Pinus brutia Ten. plantations

Abstract

Aim of study: The aim of this study was to analyze the effects of initial spacing on early growth and carbon sequestration rates in Turkish red pine plantations up to 12 years old, established with improved seeds and deep soil cultivation.Area of study: The study was conducted on experimental sites established in two locations within the Turkish red pine natural distribution areas, namely Duacı and Nebiler close to Antalya city.Material and methods: Data were collected from the experimental sites established as a Nelder design (fan-shaped), with 72 rays and 18 arcs (circles), and trees were planted (almost square) at distances ranging from 1.15 to 4.77 m. Soil type of both sites is loamy, with soil clay content varying between 70-87% in Duacı and 51-70% in Nebiler. Soils are deep being more than one m in both sites, but rockier in Nebiler, providing better soil drainage in this site.Main results: The results showed that mean total height was greater at closer spacing than those of wider spacing until age eight. Growth retardation at wider spacing in early years may be related to water loss due to evaporation in hot summer days and weed suppression. Following the age eight, competition among trees appears to be the major factor reducing the growth and carbon fixation. Diameter at breast height and individual tree volume increased, while stand volume, mean annual volume increment and annual carbon storage per hectare considerably decreased for wider spacing. Our results suggest that in order to obtain higher yield and more carbon fixation, short rotation plantations should initially be established in closer spacing, followed by thinning in subsequent years as required by silvicultural concerns. In this context, spacing 3.0 × 1.0 m or 3.0 × 1.5 m (3.0 and 4.5 m 2 growing area per tree, respectively) seems to be more plausible, providing farm machinery for maintenance and harvesting. We also found that mean annual volume increment per unit area can be considerably increased by using improved seed and deep soil cultivation in plantations.Research highlights: Results encourage managers for short rotation management in industrial plantations using closer spacing in terms of carbon sequestration as well as wood production.Keywords

Ecotypic variation and stability in growth performance of the thermophilic conifer Pinus halepensis across the Mediterranean basin

“…Differences in planting density among trials (Table 1) were considered irrelevant for primary growth at age 15 (Lanner, 1985), as it has been demonstrated for the taxonomically close Mediterranean conifer Pinus brutia at age 12 (Erkan and Aydin, 2016). Therefore, any correction for density effects was deemed unnecessary when analysing the complete trial network for stability of height responses (see section 2.5.2.…”

Application of Nelder wheel experimental design in forestry research

“…Charts presenting the behaviour of the studied tree attributes according to the growing space have been drawn by growth stages, and the observations on the trends and on the absolute values of the parameters of interest have been commented (Delwaulle, 1979;Mark, 1983;Reukema, Smith, 1987). Regression lines or curves are further approximated to the observed trajectories to explore the form and strength of the dependence on the stocking rate (Lemoine, 1980;Giordano, Hibbs, 1993;Imada et al, 1997;Otsamo, 2002;Kerr, 2003;Erkan, Aydin, 2016) and other factors, such as rectangularity and site (Newton et al, 2012). The linear or non-linear regression models have been extended also to more explicit and sophisticated analytical forms, allowing investigation of the presence and nature of spatial correlation between adjacent circumferences by modelling the error structure (Newton, 2015).…”

“…Most of the researchers find similarity between the structure of the Nelder wheel and that of familiar randomised factorial designs and adopt the respective ANOVA table to the data from their Nelder plots. One-way ANOVA is usually applied when the density effect alone for a species or genotype at a particular age is tested (Ferrere et al, 2005;Erkan, Aydin, 2016). On the other hand, ANOVA for randomised complete block design is used in most of the cases when species or genotype effect is tested together with spacing.…”

“…Plant variables commonly studied are those related to growth and productivity: % survived plants, stem diameter (basal and breast-height), mid-stem girth, total height, basal area, stem volume, total and fractional biomass, leaf area (Decourt, Lemoine,. 1974;Delwaulle, 1979;Panestsos, 1980;Mark, 1983;Krinard, 1985;Reukema, Smith, 1987;Wurtz, 1995;Imada et al, 1997;Kerr, 2003;Aphalo, Rikala, 2006;Kirongo et al, 2012;Newton, 2015;Matos et al, 2015;Erkan, Aydin, 2016). Certain physiological parameters of growth, such as plant water potential, shoot photosynthetic potential, stomatal conductance and needle chemistry (Giordano, Hibbs, 1993;Doran et al, 2001), are addressed in some investigations, while other studies examine tree form and stem quality variables: height to the crown base, crown length, diameter and volume, height-diameter ratio, live crown ratio, stem and crown form, branchiness and epicormic branching, branch diameter, crown diameter to stem diameter ratio, internode length, relative bark thickness, wood density (Lemoine, 1980;Hummel, 2000;Ferrere et al, 2005;Waghorn et al, 2007;Newton et al, 2012;Kuehne et al, 2013).…”

Initial spacing of teak (Tectona grandis) in northern Lao PDR: Impacts on the growth of teak and companion crops

“…ACIAR (2017), Bhat (1995), Erkan (2016), Holbrook and Putz (1989), Kokutse et al (2004), Laming and Van der Zee (2008), Polato and Laming (2003)…”