Loblolly-shortleaf Pine Research Articles

Region-wide characterization of structural diversity of the U.S. Outer Coastal Plain Mixed Forests Province

Forest structural diversity is related to stability, biodiversity, adaptability and resilience, as well as productivity of forest ecosystems. In this study, we characterized structural diversity of the diverse forest type groups in the southeastern Outer Coastal Plains Mixed Forest Province of the United States. We utilized data from 13,658 Forest Inventory and Analysis (FIA) plots across the region and classified them on the basis of forest type group (i.e., longleaf-slash pine, loblolly-shortleaf pine, oak-pine, oak-hickory, oak-gum-cypress, or other), disturbance type (disturbed by animal, fire, insect and disease, weather, other disturbances, or no disturbance), ownership (public or private and Native American), site condition (xeric, mesic, or hydric), stand origin (natural or planted), and age structure (one or two age classes). The structural diversity was estimated as Shannon index of tree size diversity. Our findings indicate a range of 0.00 to 2.40 for Shannon index values across the forest type groups and the ecoregion. All forest attributes (i.e., forest type groups, disturbance type, ownership, site condition, stand origin, and age structure) significantly affected structural diversity at α = 0.05. Oak-gum-cypress was structurally the most diverse forest type group. Overall, plots that were publicly owned, naturally regenerated, two-aged, and affected by weather disturbances exhibited higher structural diversity. We also created region-wide structural diversity distribution and hot spot maps. The maps identified southern Mississippi, northern and eastern Virginia, northern North Carolina, eastern South Carolina, and the border between the states of Texas and Louisiana as the structural diversity hot spots. The middle part of Outer Coastal Plain consisting of southcentral Georgia, northcentral Florida, and southwest Alabama exhibited the lowest structural diversity.

Long-term effect of periodic fire on nutrient pools and soil chemistry in loblolly-shortleaf pine stands managed with single-tree selection

Prescribed fire can be an important tool for managing loblolly (Pinus taeda L.) and shortleaf pine (Pinus enchinata Mill.) stands in the southern United States but few studies have reported the impact of repeated prescribed fires in stands that are routinely thinned or partially harvested. We compared nutrient pools and soil chemistry in portions of three uneven-aged loblolly-shortleaf pine stands that had received dormant-season prescribed fires every one to four years (high frequency fire) during a 20year period to portions of these same stands in which fire was excluded (control). The stands had been managed using single-tree selection and harvested on a 5-year cycle since the establishment of the prescribed fire treatments. Sixteen months following the last prescribed fire, forest floor nutrient pools were 42–49% less in the high frequency fire than control treatment. Understory vegetation recovered rapidly and approximately 34months following the last fire, understory biomass and nutrient pools were similar within the two treatments. However, the repeated use of prescribed fire effectively reduced the density of saplings which resulted in a 78–85% reduction in sapling biomass and nutrient pools in the high frequency fire compared to the control treatment. Chemistry of the surface (15cm) mineral soil was similar in the two treatments indicating that the prescribed fires had little impact on the mineral soil. Periodic harvesting may have ameliorated changes in mineral soil P, Ca, or Mg availability that have been reported to occur with long-term, repeated application of prescribed fires in southern pine forests. Reductions in forest floor and sapling nutrient pools associated with the prescribed fire likely had little impact on tree productivity or soil sustainability since foliar nutrient concentrations of the overstory trees in the two treatments did not differ and the potential losses were small compared to surface soil pools.

Red-cockaded Woodpecker Microhabitat Characteristics and Reproductive Success in a Loblolly-Shortleaf Pine Forest

We investigated the relationship between red-cockaded woodpecker (Picoides borealis) reproductive success and microhabitat characteristics in a southeastern loblolly (Pinus taeda) and shortleaf (P. echinata) pine forest. From 1997 to 1999, we recorded reproductive success parameters of 41 red-cockaded woodpecker groups at the Bienville National Forest, Mississippi. Microhabitat characteristics were measured for each group during the nesting season. Logistic regression identified understory vegetation height and small nesting season home range size as predictors of red-cockaded woodpecker nest attempts. Linear regression models identified several variables as predictors of red-cockaded woodpecker reproductive success including group density, reduced hardwood component, small nesting season home range size, and shorter foraging distances. Red-cockaded woodpecker reproductive success was correlated with habitat and behavioral characteristics that emphasize high quality habitat. By providing high quality foraging habitat during the nesting season, red-cockaded woodpeckers can successfully reproduce within small home ranges.

Accounting Carbon Storage in Decaying Root Systems of Harvested Forests

Decaying root systems of harvested trees can be a significant component of belowground carbon storage, especially in intensively managed forests where harvest occurs repeatedly in relatively short rotations. Based on destructive sampling of root systems of harvested loblolly pine trees, we estimated that root systems contained about 32% (17.2 Mg ha(-1)) at the time of harvest, and about 13% (6.1 Mg ha(-1)) of the soil organic carbon 10 years later. Based on the published roundwood output data, we estimated belowground biomass at the time of harvest for loblolly-shortleaf pine forests harvested between 1995 and 2005 in South Carolina. We then calculated C that remained in the decomposing root systems in 2005 using the decay function developed for loblolly pine. Our calculations indicate that the amount of C stored in decaying roots of loblolly-shortleaf pine forests harvested between 1995 and 2005 in South Carolina was 7.1 Tg. Using a simple extrapolation method, we estimated 331.8 Tg C stored in the decomposing roots due to timber harvest from 1995 to 2005 in the conterminous USA. To fully account for the C stored in the decomposing roots of the US forests, future studies need (1) to quantify decay rates of coarse roots for major tree species in different regions, and (2) to develop a methodology that can determine C stock in decomposing roots resulting from natural mortality.

Application of the generalized Faustmann model to uneven-aged forest management

In this paper, a generalized Faustmann model is developed for uneven-aged management to allow the number of years and the level of residual growing stock to vary from one cutting cycle to the next. Comparative static analyses are conducted to determine the effect of changes in interest rate, stumpage price of the trees selected for harvest, the stumpage value of the residual growing stock, and the future land value on the decision variables. The model is then applied to study the uneven-aged management of a loblolly-shortleaf pine stand in south central U.S. to determine the length of the cutting cycle and the level of residual growing stock for the first cutting cycle as well as for a case involving four cutting cycles. Sensitivity analyses reveal that for the uneven-aged loblolly-shortleaf pine stand both the length of the cutting cycle and the level of the residual growing stock are very sensitive to changes in land value in the future, in the stumpage prices of trees selected for harvest, in the stumpage prices of the residual growing stock, and in the interest rate.

Red-cockaded Woodpecker home range use and macrohabitat selection in a loblolly-shortleaf pine forest

Abstract We examined annual and seasonal home ranges of 41 Red-cockaded Woodpecker (Picoides borealis) groups from 1997 to 1999 in a Mississippi loblolly (Pinus taeda) and shortleaf (P. echinata) pine forest. Adaptive kernel annual home-range estimates (x = 43.1 ± 6.3 ha) were more conservative than maximum convex polygon estimates (x = 58.4 ± 4.5 ha). Mean non-nesting season home ranges were 15–20 ha greater than nesting season home ranges. Home ranges were smaller during nesting and increased during the post-fledging period. Compositional analysis revealed that Red-cockaded Woodpeckers selected habitats disproportionate to their availability annually and seasonally. Red-cockaded Woodpeckers selected pine sawtimber, pine poletimber, pine regeneration, and hardwood sawtimber habitats in that order. Home range appears to be a factor of landscape composition and inversely related to habitat quality.

Emergent spatial pattern of herpetofauna in Alabama, USA

Analyzing spatial pattern of regional biodiversity and its relationships with environmental factors is important for biodiversity conservation at large scales. The emergent spatial pattern of herpetofauna in Alabama is examined by combining thousands of historical records from 132 species of 24 families and environmental conditions. Our results indicate that species richness of herpetofauna increases with the increase of latitude, while it decreases with the increase of elevation. A negative spatial association exists between amphibians and reptiles on the scale of 10 km2, but 40% of habitats are still shared by amphibians and reptiles at this scale. The highest species richness of herpetofauna is in the Mobile and Baldwin Counties. Power-law relation exists between the county size and the average species richness. Total stream length, and road density are highly correlated with species richness at the county level. With the increase of annual precipitation, species richness decreases. Species richness is higher in the area with the annual average temperature around 17-18 °C. Herpetofaunal diversity in the Coosa/Tallapoosa River, the Alabama River, and the Tombigbee River basins is relatively higher than in the Perdido River and the Escatawpa River basins. The highest species richness exists at the Gulf Coastal Plain, but its species density is the lowest. The highest species richness of herpetofauna exists in the Longleaf-Slash Pine and Loblolly-Shortleaf Pine forests, while lower in Oak- Hickory forest. The emergent spatial pattern may provide important implications for herpetofauna conservation in the face of global climate change and large-scale habitat destruction. The spatial pattern and the possible underlying ecological processes have to be considered for the large scale land zoning and planning.

RED-COCKADED WOODPECKER FORAGING BEHAVIOR

Abstract We studied Red-cockaded Woodpeckers (Picoides borealis) to examine the effect of status and gender on foraging behavior. Foraging behavior of breeding pairs extended beyond separation by foraging height to include zones (bole, trunk in crown, primary limb, secondary limb) of the tree used and foraging methods (scaling, probing, excavating). Helper males and juvenile females maintained partial spatial separation from breeding adults. Helper males maintained spatial separation from breeding adults by exploiting limbs within tree crowns in both longleaf (Pinus palustris) and loblolly-shortleaf (P. taeda, P. echinata) pine forests, but also increased use of boles in loblolly-shortleaf pine in concert with reduced use of boles by adult females. Breeding males tended to forage less by scaling, probably due to the reduced proportion of foraging on boles of trees where scaling tends to predominate.

A preliminary assessment of the Montreal process indicators of air pollution for the United States.

Air pollutants pose a risk to forest health and vitality in the United States. Here we present the major findings from a national scale air pollution assessment that is part of the United States' 2003 Report on Sustainable Forests. We examine trends and the percent forest subjected to specific levels of ozone and wet deposition of sulfate, nitrate, and ammonium. Results are reported by Resource Planning Act (RPA) reporting region and integrated by forest type using multivariate clustering. Estimates of sulfate deposition for forested areas had decreasing trends (1994-2000) across RPA regions that were statistically significant for North and South RPA regions. Nitrate deposition rates were relatively constant for the 1994 to 2000 period, but the South RPA region had a statistically decreasing trend. The North and South RPA regions experienced the highest ammonium deposition rates and showed slightly decreasing trends. Ozone concentrations were highest in portions of the Pacific Coast RPA region and relatively high across much of the South RPA region. Both the South and Rocky Mountain RPA regions had an increasing trend in ozone exposure. Ozone-induced foliar injury to sensitive species was recorded in all regions except for the Rocky Mountain region. The multivariate analysis showed that the oak-hickory and loblolly-shortleaf pine forest types were generally exposed to more air pollution than other forest types, and the redwood, western white pine, and larch forest types were generally exposed to less. These findings offer a new approach to national air pollution assessments and are intended to help focus research and planning initiatives related to air pollution and forest health.

RED-COCKADED WOODPECKER NESTLING PROVISIONING AND REPRODUCTION IN TWO DIFFERENT PINE HABITATS

Abstract We obtained nestling provisioning and reproductive data from 24 Red-cockaded Woodpecker (Picoides borealis) groups occupying two different pine habitats—longleaf pine (Pinus palustris) and a mixture of loblolly (P. taeda) and shortleaf pine (P. echinata)—in eastern Texas during 1990 and 1991. Habitat data were collected within 800 m of each group's cavity-tree cluster. Feeding trips per nest and prey biomass per feeding trip were significantly greater in loblolly-shortleaf pine habitat. There were few significant correlations between reproductive/provisioning and habitat variables in either pine habitat. Pines dying from infestation by southern pine beetles (Dendroctonus frontalis) were more common in loblolly-shortleaf than in longleaf pine habitat. In addition, adult male Red-cockaded Woodpeckers weighed more in loblolly-shortleaf pine habitat. Indices of southern pine beetle abundance in loblolly-shortleaf pine habitat were negatively correlated with number of feeding trips per nestling, but p...

AVIAN COMMUNITY RESPONSE TO SOUTHERN PINE ECOSYSTEM RESTORATION FOR RED-COCKADED WOODPECKERS

The effects of Red-cockaded Woodpecker (Picoides borealis) management on nontarget birds is not widely known. Intensive management for pine specialists such as the Red-cockaded Woodpecker may negatively impact both Nearctic-Neotropical and Temperate Zone migrants associated with hardwood vegetation. To evaluate possible positive and negative associations, we surveyed avian communities from 1995–1997 using point counts within managed Red-cockaded Woodpecker cavity tree clusters and mature forest control sites in longleaf pine (Pinus palustris) and loblolly (P. taeda)-shortleaf (P. echinata) pine habitats. In general, sites managed for Red-cockaded Woodpeckers supported more diverse and numerous bird populations than mature forest control sites. During the breeding season in loblolly-shortleaf and longleaf pine habitats, respectively, species richness was 47% and 23% greater, avian abundance was 57% and 65% greater, and bird species diversity was 25% and 21% greater within managed Red-cockaded Woodpecker cluster sites than within control sites. During winter, species richness and avian abundance each were 52% higher within managed Red-cockaded Woodpecker cluster sites than control sites in loblolly-shortleaf pine habitat.

Does Prescribed Burning Have a Place in Regenerating Uneven-Aged Loblolly-Shortleaf Pine Stands?

Abstract Before the 1981 growing season, a study was installed in southeastern Arkansas to examine the effects of three dormant-season burn intervals (low, moderate, and high frequency) and an unburned treatment on natural regeneration in uneven-aged stands of loblolly and shortleaf pines (Pinus taeda andP. echinata, respectively). Merchantable pine basal areas were maintained by harvesting on a 5 or 6 yr cutting cycle. When the study began, hardwoods greater than 1 in. dbh were injected with herbicide on all plots. During the next 19 yr, there were eight high frequency, four moderate frequency, and three low frequency prescribed burns. In 1991, the unburned plots received a single, broadcast-herbicide treatment. Single-tree selection harvests were conducted in 1982, 1987, 1992, and 1997. Through 1999 (19 yr), herbicides applied at 10 yr intervals were more effective than dormant-season burns for enhancing the growth of submerchantable pines. Although recurring winter burns tended to stop the progression of both pines and hardwoods from seedling to sapling size classes, the data suggest that properly timed dormant-season burns might be used to secure natural pine regeneration in selection management. South. J. Appl. For. 26(3):117–123.

RED-COCKADED WOODPECKER FORAGING BEHAVIOR IN RELATION TO MIDSTORY VEGETATION

Red-cockaded Woodpeckers (Picoides borealis) nest and forage in pine-dominated forests. Research indicates that substantial hardwood midstory encroachment is detrimental to Red-cockaded Woodpecker populations, although the exact mechanisms are unknown. We examined foraging behavior in relation to midstory between August 1989 and February 1990. Red-cockaded Woodpeckers foraged at greater heights in areas of taller and denser midstory in the loblolly-shortleaf pine (Pinus taeda and P. echinata, respectively) habitat, but not in longleaf pine (P. palustris) habitat with less-developed midstory vegetation than typical of loblolly-shortleaf pine habitat. In addition, Red-cockaded Woodpeckers concentrated foraging activities in or adjacent to forest stands or openings with reduced midstory vegetation. Overall, Red-cockaded Woodpeckers foraged disproportionately at heights and sites that minimized their exposure to dense midstory conditions. These results suggest that ecosystem management, preferably using prescribed fire, that reduces midstory vegetation will improve foraging habitat for Red-cockaded Woodpeckers.

Does the availability of artificial cavities affect cavity excavation rates in Red-cockaded Woodpeckers?

Rates of cavity excavation by Red-cockaded Woodpeckers (Picoides borealis) were examined from 1983 to 1999 on the Angelina National Forest in east Texas. We compared the rate of natural cavity excavation between 1983 and 1990 (before artificial cavities were available) with the rate of cavity excavation between 1992 and 1999, a period when artificial cavities were regularly installed within active woodpecker cavity-tree clusters. Our comparison was restricted to cavity-tree clusters in longleaf pine (Pinus palustris) and loblolly (P. taeda)-shortleaf (P. echinata) pine habitats where woodpecker groups were present for the entire period between 1983 and 1999. Excavation rate of new cavities was significantly higher in longleaf pine habitat when artificial cavities were not available than during the subsequent period when artificial cavities were provided in all active cavity-tree clusters. In loblolly-shortleaf pine habitat, we did not detect a significant difference in the rate of new cavity excavation between the periods before and after the use of artificial cavities. We attribute the difference in results between habitats to a relative scarcity of cavities in loblolly-shortleaf pine sites due to a higher bark beetle-induced cavity tree mortality.

Revisiting the relationship between common weather variables and loblolly-shortleaf pine seed crops in natural stands

Seed production was monitored during24 years using seed-collection traps inloblolly–shortleaf pine (Pinus taeda L.–P.echinata Mill.) stands located in southeast Arkansas,north-central Louisiana, and southwest Mississippi onthe southeastern Coastal Plain, USA. Sound seedproduction was correlated with mean monthlyprecipitation and temperature from National Oceanicand Atmospheric Administration weather stationslocated near the seed-collection areas to determinethe potential of weather factors in forecasting pineseed crops. Correlations were restricted to threecritical periods in the pine reproductive cycle –strobili primordia differentiation, pollination, andfertilization. The most important (P ≤ 0.05)variables correlated with pine seed production for combined locations were cumulative precipitation (r = +0.60) during July, August, and September at 27 to 25 months before seed dispersal and mean temperature (r = −0.45) in August at 26 months before seed dispersal. Because multiple environmental factors can negatively impact pine seed development during the two yearsfollowing strobili primordia differentiation,seed-production forecasts based on weather variablesshould be verified by on-site cone counts during thesummer preceding autumn seed dispersal.

Regional frequencies of tree species associated with anthropogenic disturbances in three forest types

We used a probability-based sampling scheme to survey the forested lands of Georgia and Alabama, two adjacent states in southeastern USA. Using a nationally consistent plot design and field methods, we evaluated the presence/absence of tree species at 123 1/15 ha plots for individuals having a diameter at breast height >2.5 cm. Three forest cover types were considered: loblolly-shortleaf pine, oak-hickory, and oak-pine. Visually evident anthropogenic disturbances (e.g. artificial regeneration, logging, and prescribed burning), if any, were recorded on each plot. We classified plots with visually evident anthropogenic disturbance as `disturbed'. The remaining plots were classified as `undisturbed'. For each of the three forest types considered, mean species richness of trees was significantly greater in undisturbed plots. Of 61 species forest type combinations, eight (13.1%) had significantly different frequencies in undisturbed than in disturbed areas. In the loblolly-shortleaf pine type, five of the 18 species (27.8%) considered occurred significantly more frequently on undisturbed plots. In the oak-hickory type, two of the 21 species considered (9.5%) occurred more frequently on undisturbed plots and one species, loblolly pine, occurred more frequently on disturbed plots. Species occurring more frequently on undisturbed areas in these forest types included occupants of both the mid and upper canopy. Loblolly pine is not a common associate in the undisturbed oak-hickory forest. These results and those from other studies strongly suggest that anthropogenic disturbance, particularly clearcutting and subsequent planting of pine plantations, is having profound effect on the structure and composition of the forested area of the region. Because the three forest cover types we considered account for approximately 71% of the total forested area of the region, these results should be useful for forest management and conservation planning in the states. Management implications of mixed pine-hardwood stands vs. pine plantations in the south-east are discussed.

Uneven-Aged Silviculture, Southern Style

Abstract Data spanning 60 years on uneven-aged loblolly-shortleaf pine stands in Arkansas show that two regulation methods have been successful in regulating stand development. Key attributes of these methods are that regulation is more important than balance, residual basal area drives stand development, and regeneration is the first indicator of sustainability. Marking uneven-aged stands is best kept simple: mark to cut the poorest trees and leave the best, regardless of target structure or method of regeneration. To be successful in the long term, new methods of regulating uneven-aged and multiaged stands should share these attributes.

Red-Cockaded Woodpecker Nest-Cavity Selection: Relationships with Cavity Age and Resin Production

We evaluated selection of nest sites by male Red-cockaded Woodpeckers (Pi- coides borealis) in Texas relative to the age of the cavity when only cavities excavated by the woodpeckers were available and when both naturally excavated cavities and artificial cavi- ties were available. We also evaluated nest-cavity selection relative to the ability of naturally excavated cavity trees to produce resin, which is used by the woodpeckers to maintain a barrier against predation by rat snakes (Elaphe spp.). Longleaf pines (Pinus palustris) selected by breeding males as nest trees produced significantly greater resin yields at 2, 8, and 24 h post-wounding than cavity trees used for roosting by other group members. This preference was observed in loblolly pine (I! taeda) and shortleaf pine (I? echinata) cavity trees only at the 2-h resin-sampling period. When only naturally excavated cavities were available, Red-cock- aded Woodpeckers in both longleaf pine and loblolly-shortleaf pine habitat selected thenew- est cavities available for their nest sites, possibly as a means to reduce parasite loads. When both naturally excavated and artificial cavity inserts were available, Red-cockaded Wood- peckers continued to select the newest cavity for nesting in loblolly-shor tleaf pine habitat but not in longleaf pine habitat. Resin production in existing longleaf pine nest trees re- mained sufficient for continued use, whereas resin production in loblolly pine and shortleaf pine nest trees decreased through time, probably because of woodpecker activity at resin wells. For these latter tree species, breeding males switched to newer cavities and/or cavity trees with higher resin yields. Received 7 )uly 1997, accepted 11 November 1997.

Rehabilitation of Understocked Loblolly-Shortleaf Pine Stands—I. Recently Cutover Natural Stands

Abstract Two loblolly-shortleaf pine (Pinus taeda L.-P. echinata Mill.) stands were cut to stocking levels of 10, 20, 30, 40, and 50% to simulate recently cutover, understocked, uneven-aged stands. Number of trees ranged from 38 per acre for 10% stocking to 213 per acre for 50% stocking; comparable total basal areas were 4 and 16 ft²/ac, respectively. One stand was on a good site (site index = 90 ft at age 50), the other on a medium site (site index = 75 ft at age 50). As a rehabilitation treatment, all hardwoods 1 in. groundline diameter and larger were injected with a herbicide. At 2, 5, 10, and 15 yr after treatment, the stands were inventoried to determine: (1) rate at which the understocked stands recovered, and (2) minimum stocking levels required for successful rehabilitation. During 15 yr of rehabilitation, the understocked stands changed dramatically, and because of rapid growth of residual pines, stocking levels, basal areas, and tree volumes increasedmarkedly. Stands having at least 20% residual stocking and 5 ft²/ac of pine basal area reached an acceptable stocking level of 60% (based on number and size of trees), or 45 ft²/ac of basal area within 15 yr. Stands at this minimum stocking threshold produced 4,600 bd ft(Doyle)/ac of sawtimber volume on the good site and 3,000 bd ft/ac of sawtimber volume on the medium site during the 15 yr period. The study indicates that recently cutover, or damaged, understocked stands with at least 20% to 30% stocking or 5 to 10 ft²/ac of pine basal area can be rehabilitated to produce respectable sawtimber volumes. This management strategy provides a low-cost alternative to establishing a new stand at considerable cost to the landowner. South. J. Appl. For. 22(1):35-40.

Rehabilitation of Understocked Loblolly-Shortleaf Pine Stands—III. Natural Stands Cutover 15 Years Previously but Unmanaged

Abstract Plots in an unmanaged loblolly-shortleaf pine (Pinus taeda L.-P. echinata Mill.) stand that had been cutover 15 yr previously were established to represent five stocking levels: 10, 20, 30, 40, and 50%. The stand was on a good site (site indexLob = 90 ft at 50 yr) and had uneven-aged character. Two competition control treatments (none and individual tree release using herbicide) were also assigned. Three, five, and nine years later, the plots were reinventoried to determine: (1) the rate at which the understocked stands recovered, (2) the minimum stocking level required for successful rehabilitation, and (3) the effects of release on pine growth. The pine release treatment did not enhance stand development during the 9 yr rehabilitation period, primarily because only 18% of the pines (representing 5% of total pine basal area) were overtopped by hardwoods and were thus in need of release. However, results suggest that stands having an initial stocking of 20 to 30%, or a total basal area of 10 to 15 ft²/ac, can reach an acceptable stocking (levels of 60% for stocking, 45 ft²/ac for basal area, and 2,500 bd ft(Doyle)/ac for sawlog volume) within 15 yr or less. South. J. Appl. For. 22(1):47-52.