Taeda Plantations Research Articles

Modeling Seed Dispersal Distances: Implications For Transgenic Pinus Taeda

Predicting forest-tree seed dispersal across a landscape is useful for estimating gene flow from genetically engineered (GE) or transgenic trees. The question of biocontainment has yet to be resolved, although field-trial permits for transgenic forest trees are on the rise. Most current field trials in the United States occur in the Southeast where Pinus taeda L., an indigenous species, is the major timber commodity. Seed dispersal distances were simulated using a model where the major determinants were: (1) forest canopy height at seed release, (2) terminal velocity of the seeds, (3) absolute seed release, and (4) turbulent-flow statistics, all of which were measured or determined within a P. taeda plantation established from seeds collected from wild forest-tree stands at the Duke Forest near Durham, North Carolina, USA. In plantations aged 16 and 25 years our model results showed that most of the seeds fell within local-neighborhood dispersal distances, with estimates ranging from 0.05 to 0.14 km from the source. A fraction of seeds was uplifted above the forest canopy and moved via the long-distance dispersal (LDD) process as far as 11.9-33.7 km. Out of 10(5) seeds produced per hectare per year, roughly 440 seeds were predicted to be uplifted by vertical eddies above the forest canopy and transported via LDD. Of these, 70 seeds/ha traveled distances in excess of 1 km from the source, a distance too great to serve as a biocontainment zone. The probability of LDD occurrence of transgenic conifer seeds at distances exceeding 1 km approached 100%.

Use of energy analyses in silvicultural decision-making

Abstract Plantation managers use a variety of decision-support systems to assist in deciding on optimum silvicultural treatments. Often these include computer-based growth simulation models that include an economic analysis. We recommend that energy analyses should be added as an additional tool, to ensure that fossil and other energy is used wisely and to meet other objectives such as reducing environmental impacts. In this study, selected silvicultural inputs were evaluated for hypothetical Eucalyptus grandis and Pinus taeda plantations. Silvicultural treatments resulted in very large differences in energy output: energy input ratios, with very high ratios being associated with treatments that result from a change of site quality by overcoming major soil limiting factors. Machinery choice and other material inputs such as fertilizers and herbicides also influenced energy balance ratios. The use of nitrogen fertilizers was an energy-intensive option. The coppice eucalyptus plantation often had higher energy balance ratios than the pine because of its faster growth rate and higher basic wood density. Evaluating a combination of silvicultural treatments was not as helpful for optimizing energy balance ratios as evaluating them separately. Yield responses vary widely with species, sites and a range of operational factors. Thus determining the yield response required for a silvicultural treatment to meet a prescribed energy output: input ratio would allow managers to quickly evaluate treatments. In this study, we used an energy balance ratio of 25 as a criterion. Some treatments would have met this standard while others were marginal or the responses could not meet the criterion. However, the selection of the critical ratio needs further study. Net energy yield per hectare, evaluated for various silvicultural options, would be a useful measure in planning energy-use systems for forest estates that supply bioenergy industries. It was a less sensitive measure than energy balance for comparing different silvicultural treatments.

Irrigation and Fertilization Effects on Nantucket Pine Tip Moth (Lepidoptera: Tortricidae) Damage Levels and Pupal Weight in an Intensively-Managed Pine Plantation2

The widespread application of intensive forest management practices throughout the southeastern U.S. has increased loblolly pine, Pinus taeda L., yields and shortened conventional rotation lengths. Fluctuations in Nantucket pine tip moth, Rhyacionia frustrana (Comstock), population density and subsequent damage levels have been linked to variations in management intensity. We examined the effects of two practices, irrigation and fertilization, on R. frustrana damage levels and pupal weights in an intensively-managed P. taeda plantation in South Carolina. Trees received intensive weed control and one of the following treatments: irrigation only, fertilization only, irrigation + fertilization, or control. Mean whole-tree tip moth damage levels ranged from <1 to 48% during this study. Damage levels differed significantly among treatments in two tip moth generations in 2001, but not 2000. Pupal weight was significantly heavier in fertilization compared to the irrigation treatment in 2000, but no significant differences were observed in 2001. Tree diameter, height, and aboveground volume were significantly greater in the irrigation + fertilization than in the irrigation treatment after two growing seasons. Our data suggest that intensive management practices that include irrigation and fertilization do not consistently increase R. frustrana damage levels and pupal weights as is commonly believed. However, tip moth suppression efforts in areas adjacent to our study may have partially reduced the potential impacts of R. frustrana on this experiment.

MODELAGEM DE MATERIAL COMBUSTÍVEL EM PLANTAÇÕES DE Pinus taeda NO NORTE DE SANTA CATARINA

Um inventário foi conduzido em Três Barras, Santa Catarina, para quantificar e modelar material combustível superficial vivo e morto em plantações de Pinus taeda. De forma sistemática foram estabelecidas 20 parcelas para cada povoamento de 3, 5, 7, 9, 11, 13, 15, e 17 anos de idade, nas quais foram medidos a carga de combustível, o DAP, a altura e o diâmetro dominantes, a área basal e a espessura da liteira. Nove modelos foram ajustados através dos métodos Stepwise e “todas as regressões possíveis”. O melhor modelo para estimar a carga de acículas foi (R2 = 0,9563), ajustado com base na espessura (S) da camada de acículas. Para a carga de combustível morto de até 2,5 cm de espessura o melhor modelo foi (R2 = 0,8577). O modelo considerado mais adequado para determinação da carga total de combustível foi (R2 = 0,7034). Três gráficos para estimativa indireta do combustível e um calibrador para estimar a carga de acículas são também apresentados. FUEL MODELING IN Pinus taeda PLANTATIONS IN THE STATE OF SANTA CATARINA, BRAZIL Abstract A fuel inventory was conducted in Três Barras county, state of Santa Catarina, Brazil (26o15’ S latitude and 50o48’W longitude), in order to develop predicting models for fuel loading in loblolly pine (Pinus taeda) plantations. Sampling was done in 03, 05, 07, 09, 11, 13, 15, and 17-year-old stands, covering the whole rotation of the plantations. Twenty (20) plots of 1.0m2 (1.0x1.0m) were randomly located in each stand, totalizing 160 plots. The independent variables measured in the stands were age (in years), mean DBH (cm), dominant DBH (cm), dominant height of the trees (m), basal area (m2), and fuel bed depth (cm). The dependent variables were live surface fuel, dead foliage (needles), dead woody fuel (separated by size classes), and total fuel load, all measured in ton.ha-1 (oven dry weight). Results showed good correlation between fuel bed depth and age and most of the dependent (fuel related) variables. Live surface fuel only presented significant correlation with mean DBH and basal area. However, live surface fuel was only significant in the 3-year-old plantation, and practically disappeared when the pines canopy intercepted most of the sun light, usually after the 5th year. Models were developed to estimate the following variables: dead foliage (Wa) dead fuel up to 10-hour (Æ £ 2.5cm) timelag (W10), and total fuel load (WT). Independent variables were chosen not only by the correlation coefficients, but also for the measuring facility, and based on these principles, fuel bed depth (S), age (I), dominant height (hdom), and dominant DBH (Ddom) were selected. The models were built through the Stepwise method, using the Statistic 5.0 software. Fuel bed depth was the variable that provided best fits for all predicting models, and the inclusion of other independent variables did not improve the models precision. The best model to estimate the needles load was (R2 = 0,9563); to estimate dead fine fuel load was (R2 = 0,8577); and to estimate the total fuel load was (R2 = 0,7034). Total fuel load in the loblolly pine plantations in the studied site ranged from approximately 6.0 to 21.0 ton.ha-1.

Photosynthetic sunfleck utilization potential of understory saplings growing under elevated CO2 in FACE.

Few studies have evaluated elevated CO2 responses of trees in variable light despite its prevalence in forest understories and its potential importance for sapling survival. We studied two shade-tolerant species (Acer rubrum, Cornus florida) and two shade-intolerant species (Liquidambar styraciflua, Liriodendron tulipifera) growing in the understory of a Pinus taeda plantation under ambient and ambient+200 ppm CO2 in a free air carbon enrichment (FACE) experiment. Photosynthetic and stomatal responses to artificial changes in light intensity were measured on saplings to determine rates of induction gain under saturating light and induction loss under shade. We expected that growth in elevated CO2 would alter photosynthetic responses to variable light in these understory saplings. The results showed that elevated CO2 caused the expected enhancement in steady-state photosynthesis in both high and low light, but did not affect overall stomatal conductance or rates of induction gain in the four species. Induction loss after relatively short shade periods (<6 min) was slower in trees grown in elevated CO2 than in trees grown in ambient CO2 despite similar decreases in stomatal conductance. As a result leaves grown in elevated CO2 that maintained induction well in shade had higher carbon gain during subsequent light flecks than was expected from steady-state light response measurements. Thus, when frequent sunflecks maintain stomatal conductance and photosynthetic induction during the day, enhancements of long-term carbon gain by elevated CO2 could be underestimated by steady-state photosynthetic measures. With respect to species differences, both a tolerant, A. rubrum, and an intolerant species, L. tulipifera, showed rapid induction gain, but A. rubrum also lost induction rapidly (c. 12 min) in shade. These results, as well as those from independent studies in the literature, show that induction dynamics are not closely related to species shade tolerance. Therefore, it cannot be concluded that shade-tolerant species necessarily induce faster in the variable light conditions common in understories. Although our study is the first to examine dynamic photosynthetic responses to variable light in contrasting species in elevated CO2, studies on ecologically diverse species will be required to establish whether shade-tolerant and -intolerant species show different photosynthetic responses in elevated CO2 during sunflecks. We conclude that elevated CO2 affects dynamic gas exchange most strongly via photosynthetic enhancement during induction as well as in the steady state.

Taper equations for Pinus taeda plantations in Southern Brazil

Non-linear regression was used to fit taper functions with data from Pinus taeda plantations in Southern Brazil. Five models were evaluated: Kozak et al. (1969); a fifth-degree polynomial; Max and Burkhart (1976); Parresol et al. (1987); and Clark et al. (1991). Diameter prediction at 12 points along the stem was made to verify the accuracy and precision of these models. Furthermore, their ability to predict total and merchantable (7 cm and 25 cm top diameter) volumes was evaluated. Most of the statistics indicated that the segmented form-class model of Clark et al. (1991) was the best for estimating diameters along the stem and for predicting merchantable or total volume. However, the statistics also indicate regularity and good performance from the Max and Burkhart (1976); Parresol et al. (1987) and fifth-degree polynomial models.

A Tree Survival Equation and Diameter Growth Model for Loblolly Pine Based on the Self-Thinning Rule

1. A system of equations was developed to describe the reciprocal effects of stand density and quadratic mean diameter through time, by use of data from a loblolly pine (Pinus taeda) plantation. 2. These equations were based on the self-thinning rule, which regulates an overcrowded population by imposing a maximum mean tree size for a given stand density. 3. The system explained 98% of the variations in surviving tree number and quadratic mean diameter, and should provide reasonable extrapolation.

Hydrologic Model for Drained Forest Watershed

Modeling the hydrology of a forest watershed is helpful to understand the interaction of the hydrologic components and the effects of management activities on the performance of the system. This study was conducted to develop a hydrologic model for a drained loblolly pine (Pinus taeda) plantation watershed. Rainfall interception, subsurface drainage, and evapotranspiration models characterizing a forest watershed are described and incorporated into DRAINMOD, a hydrologic model originally developed for poorly drained agricultural fields. Simulation results are compared with measured field data collected in 1988–1989 from an intensively monitored experimental forest watershed in the coastal plain of North Carolina. Estimated drainage rates and water‐table elevations agreed well with those measured on each of three watersheds. Estimated cumulative drainage volumes for a 672‐day period were within 2–9% of measured values. The estimated water‐table elevations had an absolute average deviation of 20–22 cm for t...

Simulation and Evaluation of Water Management Systems for a Pine Plantation Watershed

Abstract Water management on forest watersheds can have off-site impacts on the environment as well as on-site impacts on soil water conditions for plant growth. This study was conducted to evaluate the hydrologic impacts and soil water implications for plant growth of alternative water management practices. The forest watershed system modeled was a loblolly pine (Pinus taeda) plantation in the Coastal Plain of North Carolina. The site is characterized by flat, poorly drained soils (thermic typic umbraquults) which are drained with open ditches 100 m apart. No drainage, free (conventional) drainage, alternative forms of controlled drainage and stocking control were modeled to determine effects on water table position and drainage outflow. Silvicultural systems, including an unthinned and a commercially thinned regime, were modeled. The water management systems were evaluated by criteria quantifying both off-site implications and on-site plant-water relationships. Controlled drainage systems were found to be successful in reducing drainage outflow rates and volumes and improving soil water conditions for tree growth. In addition, hydrologic components were examined over the life of the unthinned and thinned forest stands, from planting to harvest. Stand development and silviculture were shown to have significant effects on the hydrology of the forest. South. J. Appl. For. 16(1):48-56.

Mechanical site preparation effects on understory plant diversity in the Piedmont of the southern USA

Diversity of understory vegetation was compared among four intensities of site preparation and an adjacent 50-year-old pine-hardwood forest. The study site was a six-year-old loblolly pine (Pines taeda) plantation in the lower Piedmont of Georgia. Species richness and Shannon diversity indices were used to evaluate vine and woody (trees and shrubs) species diversity. Biomass distribution was compared among four plant categories: vines, forbs, grasses, and woody. Moderate intensity treatments (chainsaw and shear and chop) consistently ranked highest overall in diversity, with the mature pine-hardwood forest ranking lowest. Distribution of the four plant categories was not significantly affected by intensity of site preparation.

Relationship between throughfall and stand density in a Pinus taeda plantation

Throughfall was sampled from mid-May to November 1 during 1984 and 1985 in an 11-year-old Pinus taeda L. plantation subjected to various intensities of precommercial thinning. A prediction equation relating throughfall to basal area and gross rainfall for individual storms was developed. Throughfall data collected periodically during 1986 were used to test the prediction equation. Throughfall during the growing-season increased by approximately 3% of total rainfall for every 4m 2/ha reduction in basal area. Depending upon the role of stemflow, additional input to the forest floor from throughfall, when reducing the basal area from 26.6 m 2/ha to 12.6 2/ha, would range from 22 to 60 mm. This additional water would increase the amount of soil moisture available to the stand during the growing-season.

Responses of Vegetation and Deer Forage Following Application of Hexazinone

Abstract Vegetation responses were studied on a loblolly pine (Pinus taeda) plantation that had received intensive mechanical site preparation and hexazinone (1 lb/ac a.i.) for herbaceous weed control. Vegetation on plots treated by a broadcast application of granular hexazinone (Pronone® 5G) was compared to vegetation on plots that received a banded (top of bed only) application of liquid hexazinone (Velpar® L). Total plant biomass was significantly greater (P &lt; 0.10) on control plots (2,512 lb/ac, dry wt) than on broadcast (1,089 lb/ac) or banded plots (1,481 lb/ac) in September of the first growing season, but differences disappeared by the end of the second growing season. Total number of plant species on control plots (105) and banded-treated plots (97) was similar, but fewer plant species (60) were found on broadcast-treated plots the first year. At the end of the second growing season, the number of plant species was similar on all treatments. White-tailed deer (Odocoileus virginianus)forage was significantly greater on control plots (1,481 lb/ac) than on broadcast (393 lb/ac) and banded plots (534 lb/ac) in September of the first year's growth, but there were no differences after the second growing season. Pine seedling survival was lower on herbicide treated plots, but seedling height and ground line diameter were greater on herbicide treated plots. South. J. Appl. For. 11(4):176-180.

Estimates of nutrient removal, displacement and loss resulting from harvest and site preparation of a Pinus taeda plantation in the piedmont of north Carolina

Biomass and nutrient removal and redistribution were estimated for combinations of two levels of harvest utilization (stem-only vs. complete tree) and two methods of site preparation (chop/broadcast burn vs. shear-pile/disk) in the Piedmont of North Carolina. Stem-only harvest removed 57 kg ha −1 N, 5 kg ha −1 P, 35 kg ha −1 K, 52 kg ha −1 Ca and 14 kg ha −1 Mg. Complete-tree harvest increased N, P, K, Ca and Mg removal over stem-only harvest by 216, 304, 152, 254 and 151%, respectively, although biomass removal was increased by only 65%. Estimated displacement of N and P into windrows during site preparation depended on harvest utilization, but generally exceeded harvest removals by at least 200%. Nutrient losses resulting from broadcast burning were small, primarily due to ineffectual burns. Removals, displacements and/or losses of nutrients during harvest and intensive site preparation were equal for both harvest utilization levels. These amounted to 714 kg ha −1 of total N in biomass and soil, and 46, 154, 481 and 88 kg ha −1 of P, K, Ca and Mg, respectively, in biomass and Mehlich III soil extractions.

Effects of Loblolly Pine Plantations on Songbird Dynamics in the Virginia Piedmont

Avifauna was sampled in 8 developmental stages of loblolly pine (Pinus taeda) plantations and in 2nd growth pine-hardwood forests during the summer, winter, and spring seasons of 1979-80 in the central Piedmont of Virginia. During summer, the number of birds (N) peaked in the 2and 5-year-old plantations and dropped significantly (P < 0.05) in older plantations. Average N of species/stand (S), total N of species in all stands of a given developmental stage (T), and species diversity (H') followed a similar trend. N, S, and T were significantly (P < 0.05) lower in the 2nd growth forests than in younger plantations. N, S, T, and H' were lower in winter than in other seasons sampled. N, S, and H' values were higher in the 2-5-year-old pine plantations than in the older, 7-24-year-old plantations. Values for 2nd growth forests were comparable to those in the 7-24-year-old plantations. In the spring breeding season, N, S, T, and H' were similar to those found during the later summer period. Species equitability (J') remained relatively high in all stands surveyed. J. WILDL. MANAGE. 50(3):406-413 Loblolly pine is one of the major tree species used by the forest industry in Virginia. Although not native to the study area in the central Piedmont, it was introduced in the early 1930's and has proved more profitable than the native pines (Williston and Huckenpahler 1958, Smally and Pierce 1972). Abandoned farmlands were used as plantation sites until the mid-1950's when this type of land increased in value. Forest industries then were compelled to use lower value, 2nd growth hardwood stands for plantation sites by clearcutting and planting loblolly pine. This conversion practice has created major changes in the composition and structure of the vegetation found in the central Piedmont (Felix et al. 1983) and may have effects on nongame wildlife species. The objective of this study was to determine the effects of establishment and development of loblolly pine plantations on the relative density, abundance, and diversity of breeding and winter resident songbirds. We would like to acknowledge P. T. Bromley and J. D. Fraser for their reviews of earlier drafts of this paper.

A Simulation-Based Approach to Evaluating Commercial Thinning Decisions in Loblolly Pine Plantations

Abstract Computer simulation techniques are described which evaluate the impact of various stand conditions, management regimes, harvesting systems, and future market scenarios on current thinning decisions in pine plantations. Four simulation programs (PTAEDAR, PTAEDA, GENMAC, and HSS) were linked to predict tree growth/stand development and to model mechanized thinnings and final harvests. Simulation results were then combined with an investment analysis program to calculate the net present value of each strategy. An example analysis for a "typical" loblolly pine (Pinus taeda) plantation is presented. As described here, simulation is a practical method of evaluating the profitability of a wide range of alternatives, including planting spacings, thinning regimes, and rotation ages for managing future plantations of loblolly pine.

Succession in Loblolly Pine Plantations Converted from Second-growth Forest in the Central Piedmont of Virginia

Vegetation composition and structure were quantified in 21 pine stands converted from second-growth hardwood-pine forest at two state forests in Virginia. These stands included three replications each of seven developmental stages ranging in age from 1-22 years. Species richness and vegetation cover in the ground stratum showed the same trend: high values in stands 1-5 years of age followed by a decline from 5-15 years, at which point canopy closure was complete, and these variables were relatively stable for the next 7 years. A peak in transgressive stratum richness in the 9th year was followed by a similar decline and leveling off. Evenness (J') values over time were nearly constant for these understory strata, except in 3-year-old stands where a decline in ground stratum evenness occurred due to dominance by Andropogon virginicus. Increasing richness and evenness in the overstory stratum was due to growth of hardwoods. Trends in richness and evenness differed from the old-field successional model due to a high diversity of seeds and sprouts at the start of succession. Despite such differences, the seral stages typical of old-field succession were discernible in converted stand succession. However, they were somewhat abbreviated and masked by the abundance and variety of reproductive units and the rapid closure of the canopy by codeveloping pines and sprout hardwoods. INTRODUCTION The central Piedmont of Virginia is part of the Oak-Pine Forest Region delineated by Braun (1950). Young forests are characteristically dominated by Pinus virginiana and P. echinata and are gradually replaced during succession by an oak-hickory complex (Braun, 1950). From the 1700s to the early 1800s Piedmont lands were cleared, intensively farmed and abandoned (Gottmann, 1969). Abusive crop farming depleted soils and led to severe and extensive topsoil erosion (Culbertson, 1948; Gottmann, 1969). Much abandoned cropland reverted to native forest through succession. The end of the 19th century marked the beginning of a new period of deforestation when most of the commercially valuable forest of the Piedmont was harvested (Gottmann, 1969). Pinus taeda (loblolly pine) has been the principal species planted in the central Piedmont since the 1930s, even though it is incapable of natural regeneration throughout much of this region (S. F. Warner, pers. comm.). Up to the mid-1950s, most planting of P. taeda was in old fields. Owing to a decline in agricultural land abandonment, hardwood and pine-hardwood forests have been directly converted to P. taeda plantations at an accelerated rate. Whereas much is known about the vegetation dynamics of old-field succession in the Piedmont region of the Southeast (Crafton and Wells, 1934; Billings, 1938; McQuilkin, 1940; Oosting, 1942; Keever, 1950; Nicholson and Monk, 1974, 1975), little is known about such changes associated with the establishment and development of pine plantations on sites converted from second-growth forests. Thus, the objective of this study was to examine temporal changes in the composition and structure of vegetation in loblolly pine stands converted from such forests. 1 Present address: 435 Jackson Street, Fall River, Massachusetts 02721. 2 Present address: Department of Biology. 3Department of Biology.

Association ofDiplodia pineawith a Root Disease of Pines in South Africa

WINGFIELD, M. J., and P. S. KNOX-DAVIES. 1980. Association of Diplodiapinea witha root dise3sc of pines in South Africa. Plant Disease 64:221-223. Diplodia pinea is an important factor in a root disease of Pinus eJ/iotljj and P. taeda in various parts of South Africa and Swaziland. All stands in which the dise3se occurred were severely stressed. Diplodia pinea (Desm.) Kickx occurs throughout the conifer-growing areas of the world and is associated with a wide range of symptoms, including bark cankers, bud wih, dead top, seedling blight, seedling collar rot, staghead, and twig blight (1,3,4,9,12). In South Africa, D. pinea causes serious dieback of Pinus patula Sch!. & Cham., P. pinaster Ait., and P. radiata D. Don. after hail (5,7,8) and is regarded as the most important pathogen of pine plantations (8,15). Control is largely by restricting planting of susceptible species to areas where hail iamage is limited (5,6) and by replacing ISceptible species with the more tolerant elliottii Engelm. and P. taeda L. in the summer rainfall area (5-7). Since 1975, extensive losses have been caused by a root disease in P. taeda plantations belonging to the Usutu Pulp Company in Swaziland (D. G. M. Donald, personal communication). During a preliminary survey of local forest tree diseases, the senior author examined the diseased trees in Swaziland and observed similar symptoms on P. elliottii and P. taeda plantings in various parts of South Africa. This paper describes the association of D. pinea with Part of an M.Sc. thesis to be submitted by the senior author to the University of SteUenbosch. Accepted for publication 17 September 1979. 00191-2917/80/000050$03.00/0 01980 American Phy1opathologicaJ Society

Effect of fertilization on production of epigeous basidiocarps by mycorrhizal fungi in loblolly pine plantations

Basidiocarps of 39 epigeous species of proven or potential mycorrhizal fungi were found in three fertilized Pinus taeda plantation s during 1972 and 1973. The largest numbers of basidiocarps on all three plantations were found on nonfertilized plots or plots fertilized with P only. Fewest basidiocarps were found on plots fertilized with N. Numbers of basidiocarps of Suillus hirtellus were decreased by N fertilization. Numbers of basidiocarps of some other potential mycorrhizal fungi were not altered substantially by fertilization treatments. The average numbers of total living mycorrhizal tips were correlated well with average numbers of epigeous basidiocarps of proven or potential mycorrhizal fungi on fertilized plots. However, if mycorrhizal tips formed by Cenococcum geophilum, which do not form visible basidiocarps, were ignored, the remaining mycorrhizal tips were not well correlated with numbers of basidiocarps of proven or potential mycorrhizal fungi.

The use of habitat components by small mammals in eastern Australia

The effect of habitat components (vegetation density at two levels, litter, logs and roads) on the distribution of small mammals was assessed in adjacent areas of native forest and Pinus taeda plantation in north-eastern New South Wales. Rattus fuscipes was associated with structural complexity in native forest but not in pine plantation where it was found on downslope areas. R. rattus was associated with windrows in the pine plantation, R. lutreolus with areas devoid of a shrub layer in the pine plantation, Antechinus stuartii with logs and Melomys cervinipes with habitat components associated with rainforest areas. Road crossing by small mammals was inversely related to road width; roads severely restricted or stopped the movement of small mammals even when the road consisted of a long-unused and partly overgrown track.

Midstory Hardwoods Inhibit Deer Forage in Loblolly Pine Plantations

The basal area of a hardwood midstory developed inversely to the basal area of pine. Within 2 years after hardwood midstory elimination at pine age 42, herbage dry matter increased from 303.3 to 866.3 kg/ha and browse increased from 424.4 to 1,050.8 kg/ha. During the next 3 years, herbage yields increased further to 957.2 kg/ha and browse to 1,363.6 kg. The increases were directly related to hard- wood basal area before midstory elimination. After the midstory was removed herbage yields varied in- versely with pine basal area, but browse yields were not significantly influenced by pine basal area. J. WILDL. MANAGE. 41(4):677-684 The invasion and uncontrolled growth of hardwoods in loblolly pine (Pinus taeda) plantations can substantially limit the carrying capacity of millions of acres of habitat for white-tailed deer (Odocoi- leus virginianus) in the South. Without pre- scribed burning or other control measures in plantations on a sawtimber rotation, in- vading hardwoods develop a midstory of low shade that impedes the growth of herbaceous and woody forage for deer (Blair and Enghardt 1976). The density and development of a hardwood midstory is largely governed by both intensity of site preparation and thinning practices. In- tensive methods of site preparation such as discing appreciably deter hardwood inva- sion by destroying rootstocks, but such methods eliminate palatable species of woody deer forage. Periodic thinning of pine plantations enhances the midstory de- velopment by reducing competition from the dominant pine overstory. This paper de- scribes the ecological association between the pine overstory, the hardwood midstory, and understory vegetation in planted lob- lolly pine stands managed at different levels of pine basal area.