Development of Diameter Growth Models by Thinning Intensity of Planted Quercus glauca Thunb. Stands

Background and objective: This study was conducted to develop diameter growth models for thinned Quercus glauca Thunb. (QGT) stands to inform production goals for treatment and provide the information necessary for the systematic management of this stands.Methods: This study was conducted on QGT stands, of which initial thinning was completed in 2013 to develop a treatment system. To analyze the tree growth and trait response for each thinning treatment, forestry surveys were conducted in 2014 and 2021, and a one-way analysis of variance (ANOVA) was executed. In addition, non-linear least squares regression of the PROC NLIN procedure was used to develop an optimal diameter growth model.Results: Based on growth and trait analyses, the height and height-to-diameter (H/D) ratio were not different according to treatment plot (p > .05). For the diameter of basal height (DBH), the heavy thinning (HT) treatment plot was significantly larger than the control plot (p < .05). As a result of the development of diameter growth models by treatment plot, the mean squared error (MSE) of the Gompertz polymorphic equation (control: 2.2381, light thinning: 0.8478, and heavy thinning: 0.8679) was the lowest in all treatment plots, and the Shapiro-Wilk statistic was found to follow a normal distribution (p > .95), so it was selected as an equation fit for the diameter growth model.Conclusion: The findings of this study provide basic data for the systematic management of Quercus glauca Thunb. stands. It is necessary to construct permanent sample plots (PSP) that consider stand status, location conditions, and climatic environments.

Is Cork Growth a Reliable Proxy for Stem Diameter Growth in Cork Oak (Quercus suber L.)? Implications for Forest Management under Climate Change in Mediterranean Regions

Cork-ring widths have been extensively used in dendroecological studies assessing the relationship between cork growth patterns and climate (precipitation and temperature). Generally, cork growth is assumed as a proxy for stem diameter growth to address cork oak (Quercus suber L.) growth sensitivity to climate and cork yield modeling. Cork growth represents a large part of stem radial increment in this species due to the enhanced activity of phellogen when compared to the cambium activity; thus, similar inter-annual variations of cork-ring widths and tree diameter growth might be expected. However, so far, the influence of rainfall and temperature on stem diameter growth has scarcely been addressed; moreover, it is still not clear whether tree size relates, and in what way, to the variations in radial growth of cork and stem diameter and whether these reflect (proportional) quantitative variations in stem basal area growth. In this study, we computed the annual growth of cork and of stem diameter at breast-height in data series of 47 trees, from 2000 to 2012, corresponding to a full cork production cycle. Results showed a tight link between cork-ring width and stem diameter growth indices. However, while cork growth strongly correlated with climate conditions in autumn–winter prior to the growing season, stem diameter growth correlated with climate conditions of the current growing season, and, more importantly, it was tree size-related. The extrapolation from cork-ring increments to stem basal area growth is likely to progressively underestimate tree growth and biomass increment in larger cork oaks and to further bias it due to climate change effects in the Mediterranean region.

Age-age correlations and prediction of early selection age for diameter growth in a 35-years old Pinus brutia Ten. Genetic experiment

Aim of study: Forest geneticists developed various methods to predict an early selection age for forest tree species in order to shorten the breeding cycles. This study aims to estimate age-age correlations among diameter growth of trees at different ages and predict early selection age for Pinus brutia Ten. Area of study: P. brutia populations in the study were sampled from the most productive distribution range of the species, which is an important forest tree in the eastern Mediterranean Basin. To understand genetic variation and determine early selection age for the species, a common garden experiment was established in two test sites near Antalya city, Turkey, in 1979. Material and methods: Wood increment cores at breast height were collected at age 30 years, and diameters (dbh) were measured for the ages 13, 15, 19, 21, 23, 25, and 27 years on the cores. Diameters at ground level (dgl) and dbh were also measured on live trees at age 35. Variance components, age-age correlations, heritability and selection efficiency were estimated for the diameters. Main results: Age-age genetic correlations for diameters were high (mostly > 0.90). Genetic correlations between dgl (at age 35) and dbh (at all measurement ages) ranged from 0.84 to 0.99. Regressions of genetic correlation on natural log of age ratio (LAR) of juvenile age to older age were significant (P < 0.0001). Selection efficiencies estimated by employing the prediction equation indicated that for rotation age 40, the optimum selection age would be between 3 to 5 years, and for rotation age 100 it would be between 5 to 9 years. Research highlights: The results of this study provide information that can be used to find early selection ages in P. brutia. On relatively poor test sites most trees may not attain enough height growth to have measurable dbh trait. In such cases, dgl and/or tree height traits (both of which are highly correlated with dbh traits of all ages) can be measured and used instead of dbh trait for evaluations.

Daily variations in tomato stem diameter as a criterion for irrigation management

The process of daily variation in tomato stem diameter is examined in order to justify the use of this parameter to control drip irrigation. Changes in the size of individual plant parts depend on the provision of water, light, heat and nutrients to the production process. Therefore, such plant parameters as leaf temperature, xylem flow rate, fruit and stem diameter can be indicators of availability of necessary resources. The research was carried out in Novosibirsk region in June - September 2020. The value of the range of daily variations in stem diameter, which has a close relationship to relative soil moisture, was used as an indicator of plant water stress. The source of the information is the results of measurements of soil moisture and stem diameter growth of tomato. Experiments to assess the effect of water deficit on stem parameters were carried out on a plant set out in the open ground separately from the rest. Artificial water stress conditions were created by watering once a week. Data were collected using a PM-11z phytomonitor, soil moisture and stem diameter growth sensors. The results of measurements were processed in Microsoft Office Excel program. It was found that the range of daily fluctuations of stem diameter growth depends on moisture availability. When soil moisture is below 30%, the plant experiences water stress and the range of stem diameter fluctuations increases. The maximum growth in stem diameter was observed at 7-10 a.m. and the minimum at 13-15 p.m. local time. The difference between the maximum and minimum of the daily stem diameter increase characterizes the range of the daily stem diameter difference, which correlates closely with soil moisture. The correlation coefficient between them is 0.72. The limit for the daily stem diameter difference is 0.025 mm at 30% soil moisture. If the actual value of this parameter exceeds the limit value, the irrigation system can be activated. The implementation of this approach makes it possible to automate the irrigation process and to take into account the indicator that signals water stress of the plant.

Effect of Biochar and Manual Vegetation Control on Early Growth and Survival of Planted Jack Pine (Pinus banksiana Lamb.) Seedlings in Northern Minnesota

Survival of planted seedlings following a regeneration harvest can be challenging and early interventions through silvicultural treatments may be required for successful stand establishment. We tested the influence of soil amendment (biochar+compost, compost-only, or control) and vegetation control (VC; applied either initially or annually for five years using brush saws) on the growth and survival of jack pine at three sites in northern Minnesota. Application of the biochar+compost soil amendment increased seedling survival by 30% relative to the control in the first year, but there was no significant difference in survival among soil amendment treatments after five years. Both soil amendments increased diameter growth relative to the control (14% increase with biochar+compost, 10% increase with compost only), with most of the biochar+compost effect attributed to the compost. Annual VC increased diameter growth by 17% relative to initial VC, but overall effects on survival and growth were generally small relative to reported effects of VC via herbicide. The limited short-term influence of biochar and manual VC on growth and survival of jack pine indicates that these practices are likely not an effective means to increase jack pine establishment, but other benefits (e.g., increased carbon storage) may become apparent with time. Study Implications Emerging changes to forest conditions and climate are likely to create challenges for successful regeneration in even-aged silvicultural systems. Early interventions such as application of soil amendments and vegetation control may be required to increase seedling survival. However, our findings indicate that biochar application and manual vegetation control were not very effective at increasing survival and growth of planted jack pine seedlings across a range of site conditions in northern Minnesota. Further study is warranted to determine whether other biochar application rates and techniques or other forms of vegetation control are more effective for successful jack pine establishment.

Growth diversity, heritability, and genetic correlation of 4-years-old of Alstonia angustiloba progeny test in Wonogiri, Central Java

Alstonia angustiloba is a local tree species that have potential for community forest plantation; therefore, it is important to provide improved seeds. This study aimed to determine the diversity of growth, estimate the value of heritability, and the genetic correlation of the 4-years-old A. angustiloba progeny test. Randomized Completely Block Design with two factors (population and family) were used in this study. In this study, families are nested in the population. The population factors consisted of 4 levels, and family factors consisted of 43 families. The analysis of variance showed that height and stem diameter growth were significantly different between populations and families at four years old. The best height and stem diameter growth at the population level was obtained from the Pendopo population, 4.45 m and 7.71 cm, respectively. At the family level, the best height growth was obtained from 9 families (4.46-5.06 m), and the best stem diameter growth was obtained from 11 families (7.48-8.72 cm). The estimated individual heritability value for height was 0.41, and stem diameter was 0.23. Estimated family heritability values were 0.66 for height and 0.50 for stem diameter. The genetic correlation between height and stem diameter was 0.97.

Use of biopolybag from tapioca starch and sawdust waste

One alternative to overcome the weakness of polybags, namely creating plastic waste, is the use of biodegradable polybags (biopolybags) that are easily degraded so that they can be planted directly without having to be opened and disposed of. Therefore, the purpose of this study was to determine the effect of comparison between tapioca starch and sawdust pulp on mechanical properties, plant height and diameter growth, and soil chemical properties. The analysis used in this research is a tensile test using ASTM D638 2005 standard, elongation (elongation at break), elasticity (young’s modulus), and water absorption using SNI. The comparison of tapioca starch and sawdust pulp had a significant effect on the mechanical properties of the tensile strength and elongation tests, and had no significant effect on the elasticity.

Effects of Strip Roads in a Pine Tree Stand (Pinus sylvestris L.) on the Diameter Growth and Pith Eccentricity of Trees Growing along Them

Although skid roads are more and more commonly used in Poland, they are still quite often criticised due to a certain loss of wood volume and the impact on edge trees. In this context, the results of the research described in this article can be used as a substantive contribution to discussions about strip roads. Research was carried out in a 42-year-old pine tree stand (Pinus sylvestris L.) in the Notecka Forest, where thinning had been performed and 2.5 and 3.5 m wide strip roads had been cut 10 years before. The analysis comprised two five-year periods recording diameter growth and pith eccentricity in trees growing at the distance zones of 0–1 m (adjacent trees), 2–4 m and 8–10 m (the control) away from the strip roads. The differences in growth and eccentricity between the different distance zones as well as the frequency of pith eccentricity in the N-W, S-W, N-E and S-E directions were assessed, related to the distance from the strip road and the measurement height. The measurements of the analysed traits were conducted on wood discs cut from the centres of two-metre-long sections on sample trees (12 trees in each distance zone). The trees growing directly beside the strip roads were statistically significantly thicker than those growing 8–10 m away, and in the case of the trees beside the narrower strip roads, in the second 5-year period, they were also thicker than the trees from the 2–4 m distance zone. The effect of the wider strip roads in the first growth period was also significant for the trees growing 3 m away from the strip road (their growth in this period was significantly greater than that of trees in the control zone). The research into tree-pith eccentricity showed no differences due to relative distance from the strip road. Furthermore, no statistically significant relationship between the distance of trees from the strip road, measurement height and frequency of tree-pith eccentricity to the N-W and S-W were found.

Growth of three types of sengon (Paraserianthes spp.) in varying planting spaces in agroforestry system

Sopacua F, Wijayanto N, Wirnas D. 2021. Growth of three types of sengon (Paraserianthes spp.) in varying planting spaces in agroforestry system. Biodiversitas 22: 4423-4430. Sengon (Paraserianthes spp.) is a fast-growing tree species that is commonly cultivated in the agroforestry system by communities in Indonesia, mainly on Java Island. Among several types of sengon, Solomon sengon is currently gaining popularity due to the fast growth in height and stem diameter. Nonetheless, the spacing layout of selected sengon types is unclear, including Solomon sengon, which yields more optimal growth. This study aimed to examine the growth of three sengon types (i.e., Solomon F2, Solomon F1, and local Kendal) in three spacing patterns, namely 1.5x1.5m, 3x1.5m, and 3x3m. This research was conducted from October 2019 to January 2020 (three months) in the Cikabayan Forest, Bogor Agricultural University, Bogor, West Java. The parameters of sengon growth observed were plant height, height growth rate, stem diameter, stem diameter growth rate, tree volume, and canopy area. Data analysis was performed using ANOVA and continued with Duncan's. The results showed that all types of sengon had optimal growth in the agroforestry system at various spacings. The growth of Solomon F2 adapted well to denser spacings (1.5x1.5m and 1.5x3m) with the highest averages in plant height, stem diameter, volume, and canopy area of ??10.50 m, 8.65 cm, 0.36 m3, and 5.39 m2. Local Kendal had optimal growth at a wider spacing (3x3m) with the highest average stem diameter, volume, and canopy area of ??8.96 cm, 0.043 m3, and 1063 m2. While Solomon F1 adapted well to the three spacings with the highest average in plant height, the growth rate of plant height, stem diameter, volume, and canopy area of ??10.05 m, 1.54 m, 8.59 cm, 0.042 m2, and 2075.30 m2. In general, it can be concluded that the Solomon F1 sengon can adapt well to narrow distances or wide distances. While Solomon F2 is more recommended to be planted at a narrower distance and Kendal local sengon is more recommended to be planted at a wider distance to get optimal growth.