Effects of thinning and pruning on stem and crown characteristics of radiata pine (Pinus radiata D. Don)

Abstract

(5-6) Simultaneous applications of thinning and pruning are common silvicultural practices in radiata pine (Pinus radiata) forest plantations. Their separate effects on tree growth and wood quality have been well studied, but their combined effect is not clear yet. The aim of this study is to identify how thinning and pruning together affect the stem structure and properties of the pruned but also the unpruned section of the trees (the portions formed immediately after the application of these management efforts). The effects of pruning and thinning on the number of growth units per year, internode length, number of branches, and branch diameters was analyzed in managed and unmanaged stands of radiata pine grown in Chile. When used jointly, these practices generated larger individual tree volumes (135% more) and clear wood in the pruned logs; however, they also reduced the sawn wood quality of the unpruned stem section for some years after the silvicultural interventions. The managed trees showed more growth units per annual shoot and shorter internodes, thus generating more knotty wood. Moreover, managed trees showed more taper. As trees of the managed stand restore the foliar biomass lost due to pruning, managed and unmanaged stands approach the same level of canopy closure, and differences minimize.

Long-term taper and growth reductions following pruning intensity treatments in giant sequoia (Sequoiadendron giganteum)

“…Most other studies occurred at even younger stand ages, although the height at which S. giganteum were pruned in this study matches with common target heights for initial pruning (e.g. Fernández et al 2017). Given that pruning tends to occur early in stand development, it is not surprising that lower crowns would still be contributing significantly to stem growth.…”

Climate Change Impacts on Pinus pinea L. Silvicultural System for Cone Production and Ways to Contour Those Impacts: A Review Complemented with Data from Permanent Plots

“…It is common to perform pruning when umbrella pines crowns get close rather than thinning. However, this practice does not prevent trees from competing for water and nutrients, resulting in growth in height rather than in diameter [86,87] (a fact that is observed in practice by forest owners), since the tree tends to recover their photosynthetic capacity eliminated by the removal of living branches [88]. Increasing tree height increases the ratio between height and diameter, making the trees more susceptible to water shortage.…”

“…Competition determines the limitation or regulation of the access of a subject tree to limited resources-light, water, or nutrients-due to neighboring effects [6]. Thinning forest stands regulates intra-specific and interspecific competition [6], increase the availability of water and nutrients for each remaining tree, thus promoting diameter at breast height [36,88,[97][98][99][100][101][102][103][104][105][106][107] and crown [88,106,108] growth. A higher diameter at breast height [36] or crown diameter [109] has a positive effect upon cone production.…”

CRECIMIENTO RADIAL Y CONICIDAD DEL FUSTE EN PLANTACIONES CON ACLAREO DE Pinus patula SCHIEDE ex SCHLECHTENDAL & CHAMISSO

“…El índice de conicidad permite evaluar el grado de conicidad (o su complemento, cilindricidad) del fuste de los árboles. La mayoría de los estudios con cortas de aclareo enfatizan sus efectos en el crecimiento individual del arbolado o del rodal; al aumentar el espacio de crecimiento y reducir la competencia se espera un crecimiento mayor de los árboles y redistribución de la capacidad productiva del sitio entre el arbolado residual (Pape, 1999); sin embargo, también se espera que la corta ocasione aumento en la conicidad del árbol; es decir, se reduzca el valor del índice de conicidad, al aumentar la longitud de copa y el crecimiento radial en la base del árbol; en cambio, las podas ocasionan reducción de la conicidad al generar desplazamiento de la actividad cambial y mayor crecimiento radial en la parte superior del árbol (Fernández et al, 2017;Pinkard y Beadle, 2000).…”

“…Durante el periodo de estudio, los árboles de ambas parcelas aumentaron gradualmente en IC 21 , IC 31 e IC 32 hasta alcanzar valores de 0.56, 0.22 y 0.40, respectivamente, lo que implica una reducción gradual de la conicidad del fuste. Este patrón es característico del efecto ocasionado por tratamientos de poda de la copa (Fernández et al, 2017) y refleja, sin duda, la respuesta en el patrón longitudinal del crecimiento radial de los árboles debido a la reducción drástica del tamaño de la copa por la excesiva competencia de los árboles, antes y después de las cortas de aclareo; es decir, los aclareos se aplicaron tarde y no se removió el número suficiente de árboles para revertir el proceso de recesión de la copa ocasionada por la elevada competencia de espacio en la plantación.…”