Maximum growth potential in loblolly pine: results from a 47-year-old spacing study in Hawaii

2010 ◽  
Vol 40 (10) ◽  
pp. 1914-1929 ◽  
Author(s):  
Lisa J. Samuelson ◽  
Thomas L. Eberhardt ◽  
John R. Butnor ◽  
Tom A. Stokes ◽  
Kurt H. Johnsen

Growth, allocation to woody root biomass, wood properties, leaf physiology, and shoot morphology were examined in a 47-year-old loblolly pine ( Pinus taeda L.) density trial located in Maui, Hawaii, to determine if stands continued to carry the high density, basal area, and volume reported at younger ages and to identify potential factors controlling expression of maximum growth potential. Basal area and volume were similar among spacings (square: 1.8, 2.4, 3.0, and 3.7 m) and averaged 93 m2·ha–1 and 1076 m3·ha–1, respectively, and were double the maxima reported for loblolly pine in its native range. Spacing had a significant influence on density, quadratic mean diameter, and height. Ring-specific gravity and percent latewood were similar among spacing treatments but values were high compared to mainland stands. Leaf light-saturated net photosynthesis, dark respiration, stomatal conductance, and quantum yield were comparable with values reported for loblolly pine in its native range. Foliar calcium concentrations, specific leaf area, and flush number were high in the Hawaii study. Higher carrying capacity in Hawaii may be related to a more favorable climate conducive to year-round leaf carbon gain, high nutrient availability, increased flushing, and less allocation to belowground mass.

2017 ◽  
pp. 31-54
Author(s):  
Martin Bobinac ◽  
Sinisa Andrasev ◽  
Andrijana Bauer-Zivkovic ◽  
Nikola Susic

The paper studies the effects of two heavy selection thinnings on the increment of Norway spruce trees exposed to ice and snow breaks in eastern Serbia. In a thinning that was carried out at 32 years of age, 556 candidates per hectare were selected for tending, and at the age of 40, of the initial candidates, 311 trees per hectare (55.9%) were selected as future trees. In all trees at 41-50 age period, diameter increment was higher by 31%, basal area increment by 64% and volume increment by 67% compared to 32-40 age period. The collective of indifferent trees is significantly falling behind compared to future trees in terms of increment values in both observed periods. However, the value of diameter, basal area and volume increments, of the collective of "comparable" indifferent trees are lower in comparison to the values of increments of future trees by 10-15% in the 32-40 age period, and by 15-21% in the 41-50 age period and there are no significant differences. The results show that heavy selective thinnings, initially directed at a larger number of candidates for tending at stand age that does not differ much from the period of carrying out first "commercial" thinnings, improve the growth potential of future and indifferent trees, where it is rational to do the tree replacement for the final crop in "susceptible" growth stage to snow and ice breaks.


1997 ◽  
Vol 21 (4) ◽  
pp. 168-174
Author(s):  
Michael G. Shelton ◽  
Paul A. Murphy

Abstract Growth was monitored for 4 yr in a thinned stand in southern Arkansas with three pine basal areas (70, 85, and 100 ft2/ac) and three hardwood basal areas (0, 15, and 30 ft2/ac); pretreatment basal areas averaged 119 and 33 ft2/ac for pines and hardwoods, respectively. Treatments were arranged in a 3 X 3 factorial randomized complete block design with three replicates, yielding 27 permanent 0.20 ac plots. Growth variables were regressed with residual pine and hardwood basal areas. Pine basal area and volume growth increased with the pine stocking level after thinning and decreased with the level of retained hardwoods. For basal area and merchantable volume, hardwood growth largely compensated for losses in the pine component, and thus, hardwood retention had little net effect on the total growth of the stand. The greatest impact of hardwood retention was on the stand's sawtimber growth, because hardwoods did not contribute to this product class. Each 1 ft2/ac of retained hardwood basal area reduced pine sawtimber growth by 6 to 10 bd ft Doyle/ac/yr, depending on the pine stocking. Because large differences existed in the value of timber products, retaining 15 and 30 ft2/ac of hardwoods reduced the value of timber production by 13 and 24%, respectively, at 4 yr after thinning. South. J. Appl. For. 21(4):168-174.


HortScience ◽  
2009 ◽  
Vol 44 (5) ◽  
pp. 1284-1290 ◽  
Author(s):  
Jakob Markvart ◽  
Eva Rosenqvist ◽  
Helle Sørensen ◽  
Carl-Otto Ottosen ◽  
Jesper M. Aaslyng

There is increasing use of electricity for supplemental lighting in the northern European greenhouse industry. One reason for this may be to secure a high growth rate during low-light periods by an attempt to increase net photosynthesis. We wanted to clarify which period of the day resulted in the best use of a 5-h supplemental light period for photosynthesis and growth. The periods tested were supplemental light during the night, day, morning, and evening. The experiments were carried out in daylight climate chambers measuring canopy gas exchange. The air temperature was 25 °C and the CO2 level ≈900 ppm. Vegetative chrysanthemum was used, because this species responds quickly to change in light level. The leaf areas of the plant canopies were nondestructively measured each week during the 4-week experimental period. The fact that the quantum yield of photosynthesis is greater at low than at high light intensities favors the use of supplemental light during the dark period, but growth measured as dry weight of the treated plants at the end of the experiments was not significantly different given identical light integrals of the treatments. However, one experiment indicated that increased time with dark hours during day and night (24 h) might decrease net photosynthesis. The assimilation per unit leaf area was approximately the same during times of sunlight through a diffusing screen at 100 μmol·m−2·s−1 of photosynthetic photon flux (PPF) as during times of supplemental (direct) light application at PPF of 200 μmol·m−2·s−1 by high-pressure sodium lamps. We conclude that during the winter and periods of low light intensities, the daily carbon gain does not depend on the time of supplemental light application, but is linked to the total light integral. However, extended time with dark hours during day and night (24 h) might be a disadvantage because of longer periods with dark respiration and subsequent loss of carbon. Our results indicate that during times of low light conditions, it is not necessary to include factors such as the timing of supplemental lighting application to achieve higher net photosynthesis in climate control strategies.


2008 ◽  
Vol 38 (4) ◽  
pp. 721-732 ◽  
Author(s):  
Lisa J. Samuelson ◽  
John Butnor ◽  
Chris Maier ◽  
Tom A. Stokes ◽  
Kurt Johnsen ◽  
...  

Leaf physiology and stem growth were assessed in loblolly pine ( Pinus taeda L.) in response to 10 to 11 years of treatment with weed control (W), weed control plus irrigation (WI), weed control plus irrigation and fertigation (WIF), or weed control plus irrigation, fertigation, and pest control (WIFP) to determine whether increased resource availability can push productivity of loblolly pine closer to its biological growth potential expressed in favorable, exotic environments. Maximum basal area and stem biomass were 41 m2·ha–1 and 172 Mg·ha–1, respectively, in response to fertigation. Stemwood biomass production was positively and linearly related to basal area. Belowground woody biomass was highest in the WIF and WIFP treatments and averaged 50 Mg·ha–1, but the W and WI treatments exploited a greater area of soil with low-density coarse roots. Fertigation increased foliar nitrogen concentration and foliage biomass, but treatment had no effect on leaf physiological parameters or growth efficiency. Comparison with growth rates reported for loblolly pine in Hawaii revealed that loblolly pine grown in its native range can produce the high yields observed in exotic environments when stands are below maximum carrying capacity.


HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 649e-649
Author(s):  
E.D. Leonardos ◽  
M.J. Tsujita ◽  
B. Grodzinski ◽  
T.J. Blom

Leaf and whole plant gas exchange (net photosynthesis Pn, dark respiration Dr, transpiration Tr, and resistance R) of `Jacqueline' Alstroemeria, grown in pots inside a greenhouse, were measured under lab conditions using an openflow and a semi-closed system respectively. Temperature responses of apical fully expanded leaves, on flowering and non-flowering shoots, showed an optimum range for net photosynthesis (Pn) from 15 to 20 °C. Above 25 °C Pn dropped considerably as temperature increased. Leaf transpiration rates over the same range of temperature showed a similar decrease, indicating that low leaf Pn rates at higher temperatures were due in part to increased stomatal resistance. Whole plant photosynthetic response to temperature was similar to that of leaf gas exchange. The optimum temperature range for whole plant Pn was from 12 to 17 °C. These results show that moderately low temperatures are essential for carbon assimilation and efficient water use in Alstroemeria. Temperature interactions with other environmental factors will also be presented in models describing Pn rates as a function of irradiance, CO2 concentration, and temperature.


1996 ◽  
Vol 20 (4) ◽  
pp. 177-181 ◽  
Author(s):  
Harold E. Quicke ◽  
Dwight K. Lauer ◽  
Glenn R. Glover

Abstract The objective of this study was to identify effective herbicide treatments for the release of loblolly pine (Pinus taeda L.) from competing hardwoods 7 yr after treatment. The study site was a hardwood-to-pine conversion area that had been chopped and burned. Treatments included two groups of herbicides: (1) imazapyr at 1.0 lb ae/ac used alone or in combination with metsulfuron or glyphosate, and (2) glyphosate at 1.5 lb ae/ac used alone or in combination with metsulfuron. Broadcast herbicide treatments were applied in September, 1985, during the second growing season. All treatments were effective in controlling hardwoods, with the least effective treatment decreasing hardwood basal area by 55% relative to the untreated check. The pine crop trees responded with increased diameter, height, basal area, and volume. The increase in total pine volume outside bark over the untreated check ranged from 163 to 640 ft3/ac (22% to 85%) and the increase in pine basal area ranged from 13 to 40 ft2/ac (27% to 83%). No treatment resulted in significant pine mortality. Although pine height growth was stunted the year following treatment, at age 9, mean height gains on treated plots ranged from 2.7 ft to 5.6 ft. Treatments containing imazapyr performed better than treatments with glyphosate alone or in combination with metsulfuron. Imazapyr at 1.0 lb ae/ac reduced hardwood basal area to 2 ft2/ac at age nine compared to 25 ft2/ac on the untreated check plots. There was, therefore, little room for improvement from additives, indicating that combinations with lower rates of imazapyr, comparable to today' s operational rates, may be more appropriate. South. J. Appl. For. 20(4):177-181.


2000 ◽  
Vol 125 (1) ◽  
pp. 86-92 ◽  
Author(s):  
M.W. van Iersel ◽  
B. Bugbee

Long-term, whole-crop CO2 exchange measurements can be used to study factors affecting crop growth. These factors include daily carbon gain, cumulative carbon gain, and carbon use efficiency, which cannot be determined from short-term measurements. We describe a system that measures semicontinuously crop CO2 exchange in 10 chambers over a period of weeks or months. Exchange of CO2 in every chamber can be measured at 5 min intervals. The system was designed to be placed inside a growth chamber, with additional environmental control provided by the individual gas exchange chambers. The system was calibrated by generating CO2 from NaHCO3 inside the chambers, which indicated that accuracy of the measurements was good (102% and 98% recovery for two separate photosynthesis systems). Since the systems measure net photosynthesis (Pnet, positive) and dark respiration (Rdark, negative), the data can be used to estimate gross photosynthesis, daily carbon gain, cumulative carbon gain, and carbon use efficiency. Continuous whole-crop measurements are a valuable tool that complements leaf photosynthesis measurements. Multiple chambers allow for replication and comparison among several environmental or cultural treatments that may affect crop growth. Example data from a 2 week study with petunia (Petunia ×hybrida Hort. Vilm.-Andr.) are presented to illustrate some of the capabilities of this system.


Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 556
Author(s):  
Mauricio Zapata-Cuartas ◽  
Bronson P. Bullock ◽  
Cristian R. Montes ◽  
Michael B. Kane

Intensive loblolly pine (Pinus taeda L.) plantation management in the southeastern United States includes mid-rotation silvicultural practices (MRSP) like thinning, fertilization, competitive vegetation control, and their combinations. Consistent and well-designed long-term studies considering interactions of MRSP are required to produce accurate projections and evaluate management decisions. Here we use longitudinal data from the regional Mid-Rotation Treatment study established by the Plantation Management Research Cooperative (PMRC) at the University of Georgia across the southeast U.S. to fit and validate a new dynamic model system rooted in theoretical and biological principles. A Weibull pdf was used as a modifier function coupled with the basal area growth model. The growth model system and error projection functions were estimated simultaneously. The new formulation results in a compatible and consistent growth and yield system and provides temporal responses to treatment. The results indicated that the model projections reproduce the observed behavior of stand characteristics. The model has high predictive accuracy (the cross-validation variance explained was 96.2%, 99.7%, and 98.6%; and the prediction root mean square distance was 0.704 m, 19.1 trees ha−1, and 1.03 m2ha−1 for dominant height (DH), trees per hectare (N), and basal area (BA), respectively), and can be used to project the current stand attributes following combinations of MRSP and with different thinning intensities. Simulations across southern physiographic regions allow us to conclude that the most overall ranking of MRSP after thinning is fertilization + competitive vegetation control (Fert + CVC) > fertilization only (Fert) > competitive vegetation control only (CVC), and Fert + CVC show less than additive effect. Because of the model structure, the response to treatment changes with location, age of application, and dominant height growth as indicators of site quality. Therefore, the proposed model adequately represents regional growth conditions.


Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 935
Author(s):  
Mohammad Bataineh ◽  
Ethan Childs

The need for a comprehensive and mechanistic understanding of competition has never been more important as plants adapt to a changing environment and as forest management evolves to focus on maintaining and enhancing complexity. With the recent decline in shortleaf pine (Pinus echinata Mill.) land area, it is critical to determine the effects of competition on shortleaf pine and its performance against loblolly pine (Pinus taeda L.), the preferred planted replacement. We evaluate differences in shortleaf and loblolly pine 10 year mean basal area increment (BAI) and crown dimensions across a gradient of neighborhoods. Linear mixed-effects regression models were developed using BAI and several crown metrics as responses and crowding, competitor species abundance and identity, and initial size and species identity of focal tree as predictors. Crowding of focal trees negatively impacted BAI and crown size (p < 0.001, respectively). Although loblolly pine had three times higher BAI as compared to shortleaf pine within similar neighborhoods, BAI was variable, and the crowding effect did not differ between shortleaf and loblolly pine (p ranged from 0.51–0.99). Competitive impacts on focal trees did not differ by competitor identity (p ranged from 0.07–0.70). Distance-independent competition indices better explained the variation in BAI and horizontal crown metrics, while distance-dependent size ratios were more effective at evaluating vertical crown metrics. These findings highlight shortleaf pine competitive potential in mature, natural-origin stands and provide support for the restoration of pine–hardwood and hardwood–pine stratified mixtures as well as management of shortleaf pine at long rotations.


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