Growth responses to planting density and management intensity in loblolly pine plantations in the southeastern USA Lower Coastal Plain

• Published in: Annals of forest science. Vol. 68; no. 3; pp. 625 - 635
• Main Authors: Zhao, Dehai, Kane, Michael, Borders, Bruce E.
• Format: Journal Article
• Language: English
• Published: Paris Springer-Verlag 01-04-2011; EDP Sciences; Springer Nature (since 2011)/EDP Science (until 2010)
• Subjects: Agricultural sciences; Artificial regeneration. Forest nurseries. Planting; Biological and medical sciences; Biomedical and Life Sciences; Environment; Forest management; Forest management. Stand types and stand dynamics. Silvicultural treatments. Tending of stands. Natural regeneration; Forestry; Forestry Management; Fundamental and applied biological sciences. Psychology; Life Sciences; Original Paper; Silviculture, forestry; Sowing and planting; Tree Biology; Wood Science & Technology; United States; North America; America; USA; USA, Southeast; Split-plot with repeated measurements; Intensive forest management; Fertilization; Vegetation control; Functional response; Growth; Pinus taeda; Forest management; Southeast; Planting density; Coastal plain; Artificial forest stand; Softwood forest tree; Gymnospermae; Forestry; Vegetation; Coniferales; Spermatophyta
• ISSN: 1286-4560; 1297-966X
• DOI: 10.1007/s13595-011-0045-7

• Background
A culture/density study was established in 1995 in the Lower Coastal Plain of the southeastern USA to evaluate the effects of intensive silviculture and current operational practices on the growth and yield of loblolly pine plantations across a wide range of planting densities (741–4,448 trees/ha). The operational regime consisted of bedding and herbicide application in site preparation and fertilizer applications at planting and in the eighth and 12th growing seasons. The intensive management regime had additional complete competition control, tip moths control, and more repeated fertilization treatments.
• Methods
The data from 14 locations from this split-plot experiment design with repeated measurements were analyzed with a mixed-effects model approach in terms of average DBH, average height, average dominant height, survival, stand basal area, and stand volume.
• Results
In the first few years after planting, there were no significant effects of management intensity and planting density. In later years, both management intensity and planting density significantly impacted response variables, and their interaction was only significant for average diameter at breast height (DBH). Responses to intensive management in DBH were greatest at the lowest planting densities. Intensive management resulted in larger average DBH, average height, dominant height, stand basal area, and volume. Intensively managed plots had more mortality at age 12. There were negative average DBH, average height, dominant height, and survival responses but positive stand basal area and volume responses to increasing planting density. However, there were no significant differences for planting densities above 2,224 trees/ha.
• Conclusions
The results demonstrate that both management intensity and planting density significantly affect loblolly pine productivity in the Lower Coastal Plain, and their effects are additive in nature due to the general lack of interactions.