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81.
The potential for using temperature reductions to induce biocide deposition at the end of biocide treatment was assessed using
Cyproconazole to treat ponderosa pine sapwood boards. Temperature-induced deposition produced higher biocide loadings and
steeper preservative gradients from the surface inward than the more commonly used pressure-induced deposition. The results
are discussed in relation to treatment results, process time, and the ability to recover treatment components. 相似文献
82.
83.
Keith L. Belli 《New Forests》1990,4(3):193-205
The general problem of developing a model capable of exploring the survival response of seedlings to tradeoffs in the timing of spring lifting, planting and cold storage was investigated. After the construction of an overall model framework, one general and three specific functions to predict first-year survival for batches of 2 + 0 jack pine seelings were developed. The independent variables required by the functions include: cold storage duration (days), average air and soil temperature during planting (°C), cumulative degree days at time of planting (°C), ratio of terminal-to-top length at time of lifting, and cumulative degree days at time of lifting (°C). A brief example of the type of use to which such functions could be put, and an indication of the expected level of confidence that may be placed in such a prediction, is presented. The survival functions developed in this study were not designed for widespread use throughout the Province of Ontario. At most they should be limited to 2 + 0 jack pine planting stock originating from Swastika Nursery, and planted nearby.Approved for publication as Journal Article No. J-7315 of the Mississippi Agricultural and Forestry Experiment Station, Mississippi State University. 相似文献
84.
Fossil pollen, stomata and charcoal were examined from a lakesedimentary sequence in the Glen Affric National Nature Reserve,one of the largest areas of remnant native pine woodland inScotland, in order to assess ecosystem dynamics over the last11 000 years. Results reveal that pinewood communities havebeen continuously present in East Glen Affric for the last 8300years. Pinus sylvestris first arrived in the area around 9900cal. BP, but occurred in only low abundance for the subsequent1600 years. Pine populations expanded around 8300 cal. BP andremained in relatively constant abundance throughout the remainderof the Holocene. There is no evidence of a hypothesized regionalmid-Holocene pine decline at the site. Charcoalresults reveal that pinewood communities in East Glen Affricdo not appear to have been dependent on fire for either theirestablishment or their maintenance as has previously been suggested. 相似文献
85.
Seasonal fluctuations of starch in root and stem tissues of coppiced Salix viminalis plants grown under two nitrogen regimes 总被引:1,自引:0,他引:1
Seasonal changes in starch were studied at the tissue and cellular levels in roots and stems of Salix viminalis L. cuttings. Cuttings were planted in pots containing sand and grown in a controlled environment chamber in which seasons were artificially induced by changes in temperature and photoperiod. Nitrogen was supplied at optimum and low rates, and during dormancy, one-half of the plants were decapitated. Starch concentrations in root and stem tissues were determined regularly during shoot extension growth, dormancy and resprouting after dormancy. We used light microscopy (LM) combined with image analysis (IA) to determine the cellular localization and amount of starch in different cell types of stem and root tissues. Chemical analysis confirmed that starch concentrations were lower in plants receiving a high-N supply rate than in plants receiving a low-N supply rate. In all plants, the highest concentration of starch was in the roots. Light microscopy and IA showed that starch accumulated mainly in the phloem and cortical cells of both root and stem tissues. Starch grains were also regularly found in ray parenchyma cells. The amount of starch as well as the size of the grains showed strong seasonal fluctuations. In both roots and stems, starch concentrations were highest during predormancy and lowest during periods of shoot extension growth. At the time of resprouting, root cells of decapitated plants were more depleted of starch than root cells of intact plants, supporting the hypothesis that starch reserves in roots are important during the early phase of resprouting in coppice systems. 相似文献
86.
The incidence of damage caused by grey squirrels in the Turinplain was studied to assess the impact this alien species ishaving on the highly fragmented Piedmont environment, in particularon profitable cereals, poplar plantations and semi-natural woodlands.The survey of damage was conducted both by interviews to localfarmers and growers and by direct assessment using the NearestNeighbour Method on plantations and woodlands, studying randomlychosen plots in the Turin plain to gain a general overview ofthe situation. The results show a low incidence of damage causedby grey squirrels in the area: little or none was found in semi-naturalwoodlands and in agricultural crops, apart from maize whereless than 1 per cent of fields showed damage, and poplar plantationswhere 5 per cent had signs of bark stripping. Damage on maizecrops was random across the plain, but debarking damage to poplarswas mostly concentrated on the western side of the plain, andtended to occur only in particular years. Damage was concentratedclose to streams and rivers surrounding fields and plantations.The introduction of the grey squirrel in Italy has already causedecological damage such as the extinction of the red squirrelin some areas. Nevertheless, little or no information is availableon the damage this species is causing on woodlands or agriculturalareas. This study is a preliminary survey in order to fill thisgap. 相似文献
87.
Rodney L. Robichaud Jeffrey C. Glaubitz Olin E. Rhodes Jr. Keith Woeste 《New Forests》2006,32(2):179-196
We describe the development of a robust and powerful suite of 12 microsatellite marker loci for use in genetic investigations
of black walnut and related species. These 12 loci were chosen from a set of 17 candidate loci used to genotype 222 trees
sampled from a 38-year-old black walnut progeny test. The 222 genotypes represent a sampling from the broad geographic distribution
of the species. Analysis of the samples using the 12 loci revealed an average expected heterozygosity of 0.83, a combined
probability of identity of 3×10−19, and a combined probability of exclusion for paternity analysis of >0.999. The 222 genotyped trees from the progeny test
comprised 39 open-pollinated families, 29 of which (having at least five sampled progeny) were used to estimate the outcrossing
rate for the progeny trial. The same 29 families were used to construct a Neighbor-Joining dendrogram based upon allele sharing
between individuals. The multilocus estimate of the outcrossing rate was 100% (standard error of zero), higher than the 90%
level found in previous studies at the embryo stage, suggesting that both artificial and natural selection against selfs may
have occurred over the 38-year lifespan of the progeny trial. In the Neighbor-Joining dendrogram, the majority of the putative
siblings grouped together in 21 out of the 29 families, showing that the microsatellites were able to discern most of the
family structure in the dataset. Our results indicate that errors were sometimes committed during the establishment of the
progeny test. This set of microsatellite loci clearly provides a powerful tool for future applications in black walnut. 相似文献
88.
Cynthia G. Locasio B. G. Lockaby Jon P. Caulfield M. Boyd Edwards M. Keith Causey 《New Forests》1990,4(4):261-269
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.Alabama Agricultural Experiment Station Series No. 9-892325P. 相似文献
89.
This paper describes the use by family forest landowners of educational programs provided by Washington State University Cooperative
Extension (WSUCE), and the associated use of technical assistance programs provided by state and federal agencies and the
private sector. Approximately 100,000 family forest owners controlled 19% or over 1.2 M ha of Washington’s forestland and
accounted for 29% of the timber harvested in the state on a volume basis in 1998. A variety of public and private assistance
and education programs are available to encourage and help family forest owners manage their forests. In 1999 a mail survey
was conducted to evaluate use and effectiveness of Washington’s family forest assistance and education programs. Over half
of the 872 responding family forest landowners had contact with an extension educator, program or educational material, and
about three quarters of these respondents gave an overall rating of the usefulness of extension programs and materials as
good or excellent. Respondents attending WSUCE forestry educational programs have larger median land ownership size, are older,
have owned their forests longer, have a higher rate of absentee ownership, and are better educated than non-users. They are
more likely to actively manage their forests for timber production and exhibit a clearer understanding of the multiple-use
capabilities of their forests. 相似文献
90.
Summary The anatomy of periderms in three North American conifers are described and compared. The phellems of balsam fir and eastern hemlock consist of tangential bands of thin-walled phellem (TnP) separated by one, or sometimes more, cell layers of thick-walled phellem (TkP). The phellem of white spruce contains tangential bands of TnP and TkP, as well as one to several cell layers of crystalliferous phellem (CP) abaxially adjacent to every TkP zone. The TkP, and to a lesser extent the TnP, are distinctive for each of the three conifers.The terminations of phellem growth cycles in fir and hemlock are delineated by thickened adaxial suberinic walls in the last-formed layer of TnP cells. In spruce, the adaxial suberinic walls of the last-formed layer of CP cells are thickened. TkP marks the geginning of phellem growth cycles in all three conifers.TkP cells are true suberized phellem cells, not phelloids. 相似文献