Michael Kane

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

Abstract• BackgroundA 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.• MethodsThe 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.• ResultsIn 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.• ConclusionsThe 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.

Site preparation and competing vegetation control affect loblolly pine long-term productivity in the southern Piedmont/Upper Coastal Plain of the United States

Abstract• A site preparation study was established in 1986 to evaluate the effect of different site preparation treatments on growth and yield of loblolly pine (Pinus taeda L.) plantations on the Piedmont and Upper Coastal Plain regions of the southern United States. Site preparation treatments included: (1) burn only, (2) chop-burn, (3) shear-pile-disk, (4) chop-herbicide-burn, (5) herbicide-burn, and (6) herbicide-burn-herbicide.• The data from the available 19 installations at age 21 were analyzed with separate analysis of variance and a multilevel nonlinear mixed-effects modeling approach.• The herbicide-burn-herbicide treatment significantly increased average Dbh, height, basal area and volume per hectare compared to all other treatments. The burn only treatment consistently ranked worst and was followed by the chop-burn treatment. The shear-pile-disk and chop-herbicide-burn treatments had similar overall growth pattern, and will approach the same level of pine volume as the herbicide-burn treatment.• Loblolly pine mean annual increment in volume (m3 ha−1 y−1) at age 21 by treatment were: herbicide-burn-herbicide (17.9), shear-pile-disk (16.1), herbicide-burn (15.9), chop-herbicide-burn (15.4), chop-burn (14.3), and burn (11.2).• An additional chop or herbicide treatment to the burn treatment significantly increased loblolly pine yield. Complete control of both herbaceous and woody completion enhanced long-term pine productivity.Résumé• Une expérimentation destine à tester la préparation du terrain a été installée en 1986 pour évaluer l’impact de différents traitements de préparation du terrain sur la croissance et la productivité de Pinus taeda L. dans les plaines du Sud des États-Unis d’Amérique. Les traitements comprenaient : (1) un brûlis, (2) un débroussaillage suivi de brûlis, (3) un andainage automatique, (4) un débroussaillage suivi d’un traitement herbicide et d’un brûlis, (5) un traitement herbicide suivi de brûlis, (6) un herbicide suivi d’un brûlis et d’un second traitement herbicide.• Les données issues de 19 blocs ont été analysées après 21 ans de croissance, en utilisant des analyses de variance séparées ainsi qu’un modèle mixte non linéaire plusieurs niveaux.• Le traitement herbicide-brûlis-herbicide a augmenté de manière significative le diamètre à 1 m 30, la hauteur, la surface terrière et le volume sur pied par rapport à tous les autres traitements. Le brûlis seul a produit les résultats les plus médiocres, suivi par le débroussaillage-brûlis. Les traitements avec andainage et broyage et celui avec débroussaillage-herbicide-brûlis ont présenté des croissances comparables, and se rapprochent du traitement herbicide-brûlis.• L’accroissement annuel moyen à 21 ans (m3ha−1 y−1) était de 17,9 (herbicide-brûlis-herbicide), 16,1 (débroussaillage- and ainage-broyage), 15,9 (herbicide-brûlis), 15,4 (broyage-herbicide-brûlis), 14,3 (broyage-brûlis) et enfin 11,2 (brûlis seul).• En conclusion, compléter le brûlis par un traitement herbicide ou un broyage des rémanents a permis d’augmenter de manière très significative le rendement de Pinus taerda. Un contrôle précis de la competition par les herbacées et les plantes ligneuses a permis d’augmenter la productivité de Pinus taeda sur le long terme.

Prediction of calorific values, moisture, ash, carbon, nitrogen, and sulfur content of pine tree biomass using near infrared spectroscopy

Loblolly (Pinus taeda) and slash (Pinus elliottii) pine tree biomass are significant renewable energy resources for bioenergy industries in the Southeastern United States. There is a great need for evaluation of their properties (relevant to production and evaluation-screening for bioenergy extraction) by rapid but accurate analytical methods like near infrared reflectance (NIR) spectroscopy. However, no attempts have been made so far to develop useful NIR spectroscopic calibration models for analyzing biomass of these two species. In this study, acceptable NIR spectroscopic calibration models were developed for: gross calorific value, GCV (n = 181; R2 = 0.83; ratio of standard error of cross-validation to deviation, RSCD = 2.32; ratio of standard error of cross-validation to inter-quartile distance, RSCIQ = 2.68); net calorific value, NCV (n = 184; R2 = 0.83; RSCD = 2.31; RSCIQ = 2.69); ash-free calorific value, AFCV (n = 184; R2 = 0.83; RSCD = 2.24; RSCIQ = 2.49); moisture (n = 181; R2 = 0.85; RSCD = 2.54; RSCIQ = 2.30); ash (n = 180; R2 = 0.86; RSCD = 2.65; RSCIQ = 2.62); total carbon, C (n = 101; R2 = 0.95; RSCD = 3.01; RSCIQ = 5.66); total nitrogen, N (n = 87; R2 = 0.95; RSCD = 4.24; RSCIQ = 4.76); and total sulfur, S (n = 83; R2 = 0.97; RSCD = 4.17; RSCIQ = 3.05) contents of these biomasses though the calibration models for NCV and AFCV are indirect calibration. Prediction of the independent validation sets yielded good agreement between the NIR spectroscopic predicted values and the laboratory reference values for each of: GCV (n = 92; r2 = 0.89; ratio of performance to deviation; RPD = 3.01; ratio of performance to inter-quartile distance, RPIQ = 3.16); NCV (n = 91; r2 = 0.83; RPD = 2.43; RPIQ = 3.06); AFCV (n = 91; r2 = 0.80; RPD = 2.25; RPIQ = 2.83); moisture (n = 92; r2 = 0.82; RPD = 2.38; RPIQ = 2.40); ash (n = 89; r2 = 0.81; RPD = 2.30; RPIQ = 2.66); C (n = 43; r2 = 0.90; RPD = 3.14; RPIQ = 3.23); N (n = 44; r2 = 0.95; RPD = 4.33; RPIQ = 5.96); and S (n = 42; r2 = 0.93; RPD = 3.67; RPIQ = 3.24) contents, indicating that all eight calibration models had good quantitative information. The standard errors of prediction for all models were less than twice the corresponding standard error of laboratory. Therefore, precise, accurate, and rapid analysis of calorific values and C, N, S contents of these biomasses can be done using these novel NIR spectroscopic calibration models developed.

Density reduction in loblolly pine ( Pinus taeda L.) stands to increase tree C assimilation: an approach with the dual δ 13 C and δ 18 O isotope signatures in needles

Key messageIn the context of increasing droughts related to climate change, our results showed that heavy thinning and/or very low initial planting density can increase CO2assimilation rate in needles, and may be used as a short-term management strategy for loblolly pine plantation across sites prone to drought.ContextThe dry summer of 2013 provided us an opportunity to understand the CO2 assimilation rate and stomatal conductance after density manipulation treatments using the dual isotope (δ13C and δ18O) signatures in needles of planted loblolly pine (Pinus taeda L.) trees in the southeastern USA.AimsTo our knowledge, this is the first study using the dual isotope approach to examine the physiological response of loblolly pine trees, one of the most widely planted tree species in the world, to stand density manipulation treatments (i.e., thinning intensity and planting density).MethodsIn 2001–2003, trees were planted with five different planting densities, 494, 1111, 1729, 2346, and 2964 trees ha−1 at three sites. In 2009–2011, two thinning treatments (none and moderate thinning) were applied in the 1111 trees ha−1 plots, whereas three treatments (none, light and heavy thinning) were applied in the 1729 trees ha−1 plots. Response variables (specific leaf area (SLA), foliar N, δ13C and δ18O) were measured in February 2014.ResultsSLA was lower, while δ18O was higher in the 494 trees ha−1 plots than the 2964 trees ha−1 plots without thinning. In plots planted to 1729 trees ha−1 SLA was lower, while δ13C and δ18O were higher following heavy thinning than in the unthinned control. These responses plus increased crown length, DBH, and height following heavy thinning may reflect an increased tree-level CO2 assimilation rate.ConclusionOur results showed that heavy thinning and/or very low initial planting density can be used as a short-term management strategy for loblolly pine plantation across sites prone to drought.