Plots In Stands Research Articles

Sapstain and decay following fire in stands of Pinus elliottii var. elliottii near Beerburrum, south east Queensland

Summary In September and November, 1994, wildfires caused damage to 9 thousand hectares of slash pine (Pinus elliottii var. elliottii) in plantations near Beerburrum in south east Queensland. During the salvage operation sapstain and decay were monitored by periodically felling and sectioning trees in five plots in stands damaged by the November fire. Appreciable bluestain (affecting more than 10% of stem wood per plot) was first observed 10–13 weeks after the fire. Bluestain was associated with attack by the introduced bark beetle Ips grandicollis. and was initially greatest in plots where the earliest insect attack occurred. Bluestain was also dependant on moisture content and was significant where mean values fell below 100–110%, as drying occurred particularly in the outer sapwood. Trees with severe crown scorch dried more rapidly and developed substantial bluestain more quickly, except towards the base of the stem. Where less severely damaged, the sapwood of green-crowned trees dried gradually and developed bluestain more slowly, but even green-crowned trees attacked by I. grandicollis eventually became substantially bluestained. In a supplementary study in a plantation of slash pine on Bribie Island damaged in the November fire, bluestain was found only in association with attack by Ips grandicollis, which was a reliable indicator of the presence of stain in fire-damaged stands. Isolations from the bluestained sapwood regularly yielded a species of Ophiostoma apparently introduced to the fire-damaged trees by Ips grandicollis. Sphaeropsis sapinea was not isolated from stems, but was present in dry branches and remains a potential agent of bluestain under suitable conditions. Signs of decay fungi were first detected 21 weeks after the fire, and decay was identified in 71% of the study trees sampled after 49 weeks. Stands appreciably damaged in early summer fires in south east Queensland should be salvaged within 3 months to avoid significant bluestain.

Ectomycorrhizal sporocarp occurrence as affected by manipulation of litter and humus layers in Scots pine stands of different age

The effects of litter and humus layers on the occurrence of ectomycorrhizal sporocarps in 64 plots in six stands of Pinus sylvestris were studied. In 1990, litter and humus layers and herbaceous vegetation were removed (‘sod-cutting’) in plots in stands of Pinus sylvestris of different age. Removed litter and humus were added on to existing ectorganic layers (‘sod-addition’) in plots in young and middle-aged stands. Control plots were present. Surveys carried out in 1993 showed that removal of litter and humus layers enhanced numbers of species and sporocarps of ectomycorrhizal fungi. Chemical analyses showed a reduction of the N dissolved, NH 4 +, NO 3 −, P and K + concentrations and an increase of pH of ectorganic layers as a result of sod-cutting. The N concentrations of the needle samples from the Scots pine trees in the sod-cut plots were reduced compared to the control plots. Addition of litter and humus layers did not affect numbers of species and sporocarps of ectomycorrhizal fungi. Numbers of species and sporocarps of ectomycorrhizal fungi on Haplic Arenosol soil were higher than on Haplic Podzol soil. The low nutrient concentrations and organic matter content and high pH of the Haplic Arenosol soil were likely favourable for ectomycorrhizal fungi. The ectomycorrhizal species composition was also affected by the age of the Scots pine trees.

Genetic Improvement Effects on Growth and Yield of Loblolly Pine Plantations

Abstract A series of hypotheses concerning stand dynamics and growth patterns in loblolly pine plantations of improved stock relative to plantations of unimproved stock were developed and tested. Results of these tests indicated that at the seed source and family levels: (1) the shape of the height-age curve is influenced by the site, but the level of the height-age curve is influenced by the seed source or family; (2) at the seed source and family levels, the shape of the height-diameter relationship at a given age is influenced by the site and by the initial density; and (3) the level of the height-diameter relationship is affected by the seed source or family and is directly related to the dominant height of the seed source or family at that age. Indications are that by choosing the height curve carefully, differences in development among seed sources and families on a given site can be modeled by altering the level of the height-age curve. Data from temporary plots in stands planted operationally with genetically improved stock were used to test for differences in stem quality and volume relationships as compared to comparable plots from unimproved plantations. Stem quality in the improved stands was not substantially different than in unimproved stands in the same region and of the same age range. There was no difference in stem taper or individual tree volume between improved and unimproved stock. Yield equations, based on the independent variables age, average height of dominants and codominants, and surviving number of trees, were fitted to these same plot data from operationally planted improved and unimproved stands. There were no significant differences in the yield equations, indicating that a single yield equation should suffice when the independent variables are correctly specified. For. Sci. 33(3):707-724.

Crown stratification by species in even-aged mixed stands of Douglas-fir – western hemlock

The pattern of vertical stratification in mixed Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and western hemlock (Tsugaheterophylla (Raf.) Sarg.) stands was documented by observing tree interaction patterns on temporary plots in stands between 35 and 80 years old. It was found that Douglas-fir predictably dominated the hemlock. Several possible causes of the stratification were studied. They were differences in ages between species, differences in mortality patterns, and differences in growth rates. Increment borings of trees on sample plots in the 35- to 80-year stands with the observed stratification revealed the overtopping Douglas-firs and suppressed hemlocks to be essentially of the same age. Searches for dead or dying Douglas-fir in groups of mixed stands of 35 to 80 years, 22 to 35 years, and less than 12 years revealed very little Douglas-fir mortality by suppression. Therefore, the possibility of death of intermediate and suppressed Douglas-firs was not an important factor leading to Douglas-firs being found primarily in the upper crown positions. Height and diameter growth patterns of closely growing codominant Douglas-firs, co-dominant hemlocks, and suppressed hemlocks were documented by stem analyses. Douglas-fir became significantly taller than the hemlocks after about 20 years and suppressed competing hemlocks. The possibility of stratification in mixed planted stands is less certain, since only young planted stands were available for study. Management of such mixed stands appears to improve the yield and quantity of wood and reduce or eliminate costly precommercial thinnings.