Longleaf Pine Plantations Research Articles

Production physiology of three native shrubs intercropped in a young longleaf pine plantation

The objective of this study was to evaluate how competition would affect the physiology, and thus productivity of American beautyberry (Callicar- pa americana L.), wax myrtle (Morella cerifera (L.) Small) and inkberry (Ilex glabra (L.) A. Gray) when intercropped in a longleaf pine (Pinus palustris Mill.) plantation in the southeastern United States. The effect of competition was assessed via comparisons of mortality, biomass, light transmittance, gas exchange and soil moisture between intercropping and mono- culture (treeless) treatments. Overall, shrubs in the intercropping treatment performed worse than those in the monoculture, with higher mortality, and reductions in biomass of 75.5, 50.6, and 68.7% for C. americana, M. cerifera and I. glabra, respectively. Root-shoot ratios for all species were significantly higher and soil moisture during dry periods was significantly lower in the intercropping treatment. Light transmittance below the pine canopy was high (57.7%) and I. glabra was the only species that exhibited reduced Amax when belowground resources were not limiting. These results suggest that the effect of shading is minimal and belowground competition is likely the most important determinant of productivity in this system.

Predicting Diameter Distributions for Young Longleaf Pine Plantations in Southwest Georgia

Abstract Parameter prediction equations for the Weibull distribution function were developed based on four percentile functions and a parameter recovery method for longleaf pine (Pinus palustris Mill.) in Southwest Georgia. Four percentiles were expressed as functions of stand-level characteristics based on stepwise regression and seemingly unrelated regression. Using a percentile-based parameter recovery method (PCT), estimated diameter distributions were obtained from available stand-level variables. The PCT method was also compared with a cumulative distribution function (CDF) regression method. The PCT method produced consistently better goodness-of-fit statistics than the CDF method. The results indicate that diameter distribution in longleaf pine stands can be successfully characterized with the Weibull function.

Compatible Stem Taper, Volume, and Weight Equations for Young Longleaf Pine Plantations in Southwest Georgia

Abstract Outside and inside bark diameter measurements were recorded from tree disks obtained at 0-, 0.5-, 2.0-, 4.5-, 6.0-, 16.6-, and at 4-ft-height intervals above 6 ft to a 2-in. diameter outside bark top diameter on 42 longleaf pine trees selected from intensively managed longleaf pine (Pinus palustris Mill.) plantations in Dougherty and Worth Counties in southwest Georgia. Trees were sampled from unthinned, cutover stands in their 11th and 14th growing season, which are currently part of an existing growth and yield study. Sample trees ranged from 2 to 7 in. in diameter and from 18 to 40 ft in total height. Parameters for a segmented polynomial taper and compatible cubic foot volume and weight equation were simultaneously estimated using a seemingly unrelated nonlinear fitting procedure to volumes based on a generalized Newton formula and an overlapping bolt methodology. Average error was approximately 0.25 in., 0.04 ft3, and 2.5 lb for taper, volume, and weight estimation, respectively.

Measuring external mycelia production of ectomycorrhizal fungi in the field: the soil matrix matters

Assessing mycorrhizal fungi production in field settings has been hindered by the inability to measure external mycelia. Recently, external mycelia production was measured in the field using a novel in-growth core technique with acid-washed sand as the in-growth matrix. Here, we tested the assumption that external mycelia production in acid-washed sand is representative of that in native soil. External mycelia production was estimated as the difference in fungal growth between closed (allowing only saprotrophic fungal production) and open (allowing mycorrhizal and saprotrophic fungal production) cores using a factorial design of soil matrices (acid-washed sand vs native) and fertilization treatments (control vs nitrogen (N)) in a longleaf pine (Pinus palustris) plantation. In native soils, the ectomycorrhizal to saprotrophic fungal biomass signal was strong and consistent facilitating the assessment of external mycelia production, which was 300% higher than corresponding rates in acid-washed sand and inversely correlated with soil N. These results demonstrate the efficacy and importance of using native soil as the in-growth matrix to measure ectomycorrhizal fungi external mycelia production in field settings.

Soil fertility and plant growth in soils from pine forests and plantations: Effect of invasive red imported fire ants Solenopsis invicta (Buren)

Summary Through nest building and foraging activities, ants alter physical properties and nutritional status of soils through structural modifications and nutrient accumulation. In turn, these alterations may enhance soil quality for plant growth. This study examined the effect of the invasive red imported fire ant, Solenopsis invicta Buren, on soil properties and plant growth. In our greenhouse study, ant activity decreased soil pH and increased phosphorus (P + ) and potassium (K + ) in the soil. We collected soil from within and adjacent to randomly selected nests in two common habitats of Louisiana – longleaf-pine ( Pinus palustris ) forests and longleaf-pine plantations. After physical and chemical properties were measured, Gardenia japonicus seedlings were planted in the soil to determine growth rate. In comparison to adjacent soil, ant nest soils from both habitats were lower in moisture content and bulk density and higher in NH 4 + . Ant nest soils were also higher in Ca 2+ , Mg 2+ , K + and Na + than in adjacent soils in longleaf-pine forests. G. japonicus seedlings grown in nest soil from pine forests were an average of three times taller than those grown in adjacent soil, and those from pine plantations were twice as tall as those grown in adjacent soils. These results suggest that invasive fire ants alter the physical and chemical properties of the soil. These soil modifications enhance plant growth since NH 4 + , a nutrient that limits growth, has been increased.

Fine Root Carbon Allocation and Fates in Longleaf Pine Forests

Abstract The patterns and mechanistic controls of fine root production and mortality in a 19-year-old longleaf pine (Pinus palustris Miller) plantation were assessed using minirhizotrons in a complete factorial design experiment that manipulated root carbon source and sink strengths. Carbon source strength to roots was manipulated through foliar scorching, carbon sink strength in roots was altered via nitrogen fertilization, and carbon transfer from roots to the soil organic matter pool was impacted using a general soil pesticide to distinguish between root mortality via herbivory and senescence. Fertilization significantly increased fine root nitrogen concentrations and mortality rates in the nonscorched plots across the last four sample intervals. Scorching significantly reduced fine root biomass. The influence of soil herbivores on fine root carbon allocation and fates could not be assessed in this study because the soil pesticide had no measurable effect on herbivorous nematode and insect larvae populations. The results of this study suggest that nitrogen increases fine root mortality via an increase in fine root carbon sink strength rather than a decrease in carbon allocation to fine roots. These findings support the constant allocation hypothesis regarding nitrogen controls on fine root carbon allocation and transfers in forest ecosystems. FOR. SCI. 50(2):177–187.

Above- and Belowground Competition from Longleaf Pine Plantations Limits Performance of Reintroduced Herbaceous Species

Abstract Although overstory trees limit the abundance and species richness of herbaceous vegetation in longleaf pine (Pinus palustris Mill.) plantations, the responsible mechanisms are poorly understood because of confounding among limiting factors. In fall 1998, research was initiated to determine the separate effects of above- and belowground competition and needlefall from overstory pines on understory plant performance. Three 13- to 15-yr-old plantations near Aiken, SC, were thinned to 0, 25, 50, or 100% of nonthinned basal area (19.5 m2 ha-1). Combinations of trenching (to eliminate root competition) and needlefall were applied to areas within each plot, and containerized seedlings of 14 perennial herbaceous species and longleaf pine were planted within each. Overstory crown closure ranged from 0 to 81%, and soil water and available nitrogen varied consistently with pine stocking, trenching, or their combination. Cover of planted species decreased an average of 16.5 and 14.1% as a result of above- and belowground competition, respectively. Depending on species, needlefall effects were positive, negative, or negligible. Results indicate that understory restoration will be most successful when herbaceous species are established within canopy openings (0.1–0.2 ha) managed to minimize negative effects from above- and belowground competition and needlefall.

Competition effects on wiregrass (Aristida beyrichana) growth and survival

We investigated neighboring plant effects (competition and facilitation)on wiregrass establishment in two frequently encountered restoration situationsof former longleaf pine-wiregrass habitats in the Southeastern United States:longleaf pine plantations and previously cultivated fields. In the plantationexperiment, we specifically examined canopy removal, neighboring wiregrassdensity, and aboveground and belowground effects on establishment and growth ofwiregrass seedlings at two different ages (3 weeks and 6 months) with 3competitive exclusion treatments (aboveground exclusion, belowground exclusion,or no exclusion). Competition treatment effects were age-dependent forsurvivorship and growth. Survival of 6 month old seedlings was unaffected bycompetition treatment; whereas, three week old seedling survival was greatestwhere roots were excluded. Seedling size increased with root exclusion for 6month seedlings, but not for 3 week old seedlings in plots lacking neighboringwiregrass. Where wiregrass was present, both 3 week and 6 month old seedlingsincreased growth with root exclusion. Furthermore, where neighboring wiregrassplants were absent, increasing canopy density resulted in decreased seedlingsize, but did not affect survivorship. In old fields, fertilizer treatments andweeding effects were also assessed using 3 week and 6 month old seedlings.Fertilizer application did not benefit seedling survival or growth and reducedsurvivorship of 3 week old seedlings. Seedlings were smaller where neighboringold field, weedy vegetation was present regardless of wiregrass seedling age;whereas, survival was dependent on seedling age at time of planting. Six monthold seedling survivorship remained high regardless of weeding treatment. It isstill unclear whether fertilizer application is beneficial to the successfulestablishment of wiregrass.

Vegetation composition and structure of southern coastal plain pine forests: an ecological comparison

Longleaf pine ( Pinus palustris) ecosystems are characterized by a diverse community of native groundcover species. Critics of plantation forestry claim that loblolly ( Pinus taeda) and slash pine ( Pinus elliottii) forests are devoid of native groundcover due to associated management practices. As a result of these practices, some believe that ecosystem functions characteristic of longleaf pine are lost under loblolly and slash pine plantation management. Our objective was to quantify and compare vegetation composition and structure of longleaf, loblolly, and slash pine forests of differing ages, management strategies, and land-use histories. Information from this study will further our understanding and lead to inferences about functional differences among pine cover types. Vegetation and environmental data were collected in 49 overstory plots across Southlands Experiment Forest in Bainbridge, GA. Nested plots, i.e. midstory, understory, and herbaceous, were replicated four times within each overstory plot. Over 400 species were identified. Herbaceous species richness was variable for all three pine cover types. Herbaceous richness for longleaf, slash, and loblolly pine averaged 15, 13, and 12 species per m 2, respectively. Longleaf pine plots had significantly more ( p < 0.029) herbaceous species and greater herbaceous cover ( p < 0.001) than loblolly or slash pine plots. Longleaf and slash pine plots were otherwise similar in species richness and stand structure, both having lower overstory density, midstory density, and midstory cover than loblolly pine plots. Multivariate analyses provided additional perspectives on vegetation patterns. Ordination and classification procedures consistently placed herbaceous plots into two groups which we refer to as longleaf pine benchmark (34 plots) and non-benchmark (15 plots). Benchmark plots typically contained numerous herbaceous species characteristic of relic longleaf pine/wiregrass communities found in the area. Conversely, non-benchmark plots contained fewer species characteristic of relic longleaf pine/wiregrass communities and more ruderal species common to highly disturbed sites. The benchmark group included 12 naturally regenerated longleaf plots and 22 loblolly, slash, and longleaf pine plantation plots encompassing a broad range of silvicultural disturbances. Non-benchmark plots included eight afforested old-field plantation plots and seven cutover plantation plots. Regardless of overstory species, all afforested old fields were low either in native species richness or in abundance. Varying degrees of this groundcover condition were also found in some cutover plantation plots that were classified as non-benchmark. Environmental variables strongly influencing vegetation patterns included agricultural history and fire frequency. Results suggest that land-use history, particularly related to agriculture, has a greater influence on groundcover composition and structure in southern pine forests than more recent forest management activities or pine cover type. Additional research is needed to identify the potential for afforested old fields to recover native herbaceous species. In the interim, high-yield plantation management should initially target old-field sites which already support reduced numbers of groundcover species. Sites which have not been farmed in the past 50–60 years should be considered for longleaf pine restoration and multiple-use objectives, since they have the greatest potential for supporting diverse native vegetation.

Understory vegetation, resource availability, and litterfall responses to pine thinning and woody vegetation control in longleaf pine plantations

In six 8- to 11-year-old plantations of longleaf pine (Pinus palustris Mill.) near Aiken, S.C., responses of understory vegetation, light, and soil water availability and litterfall were studied in relation to pine thinning (May 1994), herbicidal treatment of nonpine woody vegetation (1995-1996), or the combined treatments (treatment responses described below are in absolute units). Treatment differences in fifth-year (1998) herbaceous species density were as follows: pine thinning &gt; woody control = combined treatments &gt; untreated (33, 30, 30, and 25 species per 40 m2, respectively). Forb and grass covers were 13 and 8% greater, respectively, after pine thinning and 7 and 9% greater after woody control. Pine thinning stimulated a large increase in third-year gap fraction (0.26), short-term increases in soil water content (1%), and a reduction in pine litterfall by half (-120 g·m-2 per year). Woody control had no effect on gap fraction, decreased litterfall of nonpine woody vegetation (-32 g·m-2 per year), and stimulated season-long increases in soil water content (1-2%). The ranking of factors affecting herbaceous vegetation responses was as follows: light &gt; soil water &gt; herbicides &gt; litterfall. Herbaceous species density and cover can be promoted in longleaf pine plantations by intensive thinning of pines and herbicidal control of non-pine woody vegetation.

Understory vegetation, resource availability, and litterfall responses to pine thinning and woody vegetation control in longleaf pine plantations

In six 8- to 11-year-old plantations of longleaf pine (Pinus palustris Mill.) near Aiken, S.C., responses of understory vegetation, light, and soil water availability and litterfall were studied in relation to pine thinning (May 1994), herbicidal treatment of nonpine woody vegetation (1995-1996), or the combined treatments (treatment responses described below are in absolute units). Treatment differences in fifth-year (1998) herbaceous species density were as follows: pine thinning > woody control = combined treatments > untreated (33, 30, 30, and 25 species per 40 m2, respectively). Forb and grass covers were 13 and 8% greater, respectively, after pine thinning and 7 and 9% greater after woody control. Pine thinning stimulated a large increase in third-year gap fraction (0.26), short-term increases in soil water content (1%), and a reduction in pine litterfall by half (-120 g·m-2 per year). Woody control had no effect on gap fraction, decreased litterfall of nonpine woody vegetation (-32 g·m-2 per year), and stimulated season-long increases in soil water content (1-2%). The ranking of factors affecting herbaceous vegetation responses was as follows: light > soil water > herbicides > litterfall. Herbaceous species density and cover can be promoted in longleaf pine plantations by intensive thinning of pines and herbicidal control of non-pine woody vegetation.

Biomass and Taper for Trees in Thinned and Unthinned Longleaf Pine Plantations

Abstract Longleaf pine (Pinus palustris Mill.) trees growing in thinned plantation studies in Louisiana and Texas and unthinned stands from the Louisiana sites were sampled for establishing taper, volume, and specific gravity. Stem analysis data were collected on 147 stems ranging in age from 30 to 50 yr. Analyses of covariance (ANCOVAs) were employed to determine coefficients and to detect differences among treatments, for tree taper and specific gravity. Taper and volume equation coefficients and statistics at specified ages were developed for intermediate plantation ages by examining and aging internal growth rings from the stem sections. Biomass was computed by combining the taper and specific gravity equations. Seemingly unrelated regression (SUR) was used to simultaneously fit the system of four equations composed of specific gravity, taper, volume, and biomass, because of the correlated error structure of these equations. Biomass equations, however, could not be developed for the intermediate ages because specific gravity could not be determined or related to earlier tree ages. South. J. Appl. For. 19(1):29-35.

Variations in height-over-age curves for young longleaf pine plantations

Variations in height-over-age curves for young longleaf pine plantations

Timber Thinning and Prescribed Burning as Methods to Increase Herbage on Grazed and Protected Longleaf Pine Ranges

Selective commercial timber thinning and prescribed burning are effective tools in maintaining a productive forage resource on stocked range of longleaf pine (Pinus palustris). Productive mixtures of herbaceous species can be sustained through periodic timber thinning to maintain 12 to 20 m2/ha of longleaf pine basal area and rotational winter burning, at 3-year intervals. Two to three years of heavy use can be expected after patch cutting if the area of patch cuts constitute a minor percentage of the total grazed range unit. Heavy use may convert patch cuts predominantly to carpetgrass and forested range to a mixture of forbs. Pine plantations throughout the South can be managed for concurrent production of wood fiber and forage (Pearson et al. 1971, Grelen and Enghardt 1973, and Hart et al. 1970). With proper management, continuous grazing by cattle is not detrimental to establishing and growing artificially regenerated pine plantations (Pearson et al. 1971), nor is forage production seriously diminished by pine canopies until plantations approach 10 years of age (Wolters 1973). Many longleaf pine (Pinus palustris) plantations are rapidly approaching or have already attained commercial timber size and could be thinned to generate immediate cash income. Observations and available literature suggest that selective tree removal or patch cutting within a plantation drastically alters forage production and livestock utilization patterns; thus, the current study was started to determine what effects the rate of tree removal had on concurrent forage production, its botanical composition, and utilization by cattle when the range was burned by controlled backfire every third year. Findings will facilitate development of guidelines to integrate management of timber and forage on longleaf pine ranges.

Ant Communities of Southeastern Longleaf Pine Plantations

The ant community in a recent replant longleaf pine plantation on the Savannah River Plant, S.C. had the greatest species diversity and richness when compared to mature, thinned and burned pine plantations. Four species of ants dominated all pine plantations: Crematogaster lineolata (Say), Aphaenogaster traetae Forel, Aphaenogaster fulva Roger and Conomyrma insana Roger. There is an apparent relationship between the channelization of stumps, snags and dead logs by termites and densities of Crematogaster spp. Recent burning of pine straw had no measurable effect on the dominant tree bole/stump nesting species.

Response of longleaf pine plantations to litter removal

Potential impact of litter removal in longleaf pine (Pinus palustris Mill.) plantations includes disruption of both hydrologic and macronutrient cycles. Both could cause growth reduction of plantation trees. In longleaf pine plantations on the Savannah River Plant which were examined 2 or 3 years following litter removal, growth (as determined by ring analysis) was reduced in the first year following removal. Growth reduction may also continue through the second year. Due to the rapid response to litter removal, disruption of the hydrologic cycle seems most probable. No differences were found in macronutrient concentration of foliage or litter components between treatments. The economic benefit of this practice must be evaluated in light of the observed growth reduction to determine the overall costs of this practice.

Water stress in longleaf pine induced by litter removal

Forest litter layer acts as a nutrient pool to support future growth of trees and as a blanket which intercepts and absorbs rainfall and insulates soil from evaporative water loss. Litter disturbance can modify either of these functions. Soil moisture content and xylem pressure potential were determined in a longleaf pine plantation for 7 weeks following litter removal. Two weeks following treatment, xylem pressure potential of trees in control, red straw removal and total litter removal plots diverged. Trees in the total litter removal plot had the lowest xylem pressure potential (i.e. most stressed), control trees had the highest xylem pressure potential, and trees in the red straw removal plot were intermediate. Differences in xylem pressure potential among treatments were consistent throughout the season, regardless of precipitation or drought. Soil moisture content also showed different patterns based on the particular litter removal treatment. Differeces in soil water content and xylem pressure potential could explain observed growth reductions of trees in plantations where litter had been removed. Therefore consideration of the potential modification of both the hydrologic and nutrient cycles should be made prior to litter removal.

Growth in a Young Managed Longleaf Pine Plantation

Growth in a Young Managed Longleaf Pine Plantation

Root Extension in a Longleaf Pine Plantation

Root extension in a 24—year—old longleaf pine plantation in the North Carolina sandhills was studied by the application of 10 mc of I131 directly to the soil, on the surface, or at depths of 1 or 3 ft, and surrounding trees monitored with a portable scintillation counter. Within 10 ft of the point of application, all trees above 3.0 inches absorbed I131 in sufficient quantities to be detected. Beyond 22 ft for surface applications, and 33 ft for 1— and 3—ft depths, no I131 was detected in any trees. Regressions were computed to determine whether root extension could be predicted. When distance from the point of application was used as the dependent variable, an index of competition and the angle from the tree row proved to be the most useful, to the exclusion of the various measures of tree size.