Prediction model of moisture content of dead fine fuel in forest plantations on Maoer Mountain,Northeast China

Preventing and suppressing forest fires is one of the main tasks of forestry agencies to reduce resource loss and requires a thorough understanding of the importance of factors affecting their occurrence.This study was carried out in forest plantations on Maoer Mountain in order to develop models for predicting the moisture content of dead fine fuel using meteorological and soil variables.Models by Nelson(Can J For Res 14:597-600,1984) and Van Wagner and Pickett(Can For Service 33,1985) describing the equilibrium moisture content as a function of relative humidity and temperature were evaluated.A random forest and generalized additive models were built to select the most important meteorological variables affecting fuel moisture content.Nelson's(Can J For Res 14:597-600,1984) model was accurate for Pinus koraiensis,Pinus sylvestris,Larix gmelinii and mixed Larix gmelinii—Ulmus propinqua fuels.The random forest model showed that temperature and relative humidity were the most important factors affecting fuel moisture content.The generalized additive regression model showed that temperature,relative humidity and rain were the main drivers affecting fuel moisture content.In addition to the combined effects of temperature,rainfall and relative humidity,solar radiation or wind speed were also significant on some sites.In P.koraiensis and P.sylvestris plantations,where soil parameters were measured,rain,soil moisture and temperature were the main factors of fuel moisture content.The accuracies of the random forest model and generalized additive model were similar,however,the random forest model was more accurate but underestimated the effect of rain on fuel moisture.     

DYNAMIC MODELS OF MOISTURE CONTENT OF FOREST FUELS

INTRODUCTIoNMoisturecontentoffOrestfuelsaffects.ignitionprobability,rateofspread,radia-tionefficiencyandenergyrelease.Itisoneofthemajorvariablesfordeterminingfireoccurrence,evaluatingfiredangerandpre-dictingfirebehavior.Obviouslyfuelmois-turecontentisevidenceonwhichisbasedtodetermineprescribedburning.Thechangeoffuelmoisturecontentisaffectedbymanyfactors.Thedynamicmodelsoffuelmoisturecontentcanbeestablishedinaccordancewiththosefactors.lnthispaper,thetheoryofrelativemoisturecontent,develope…     

An economic assessment of industrial forest plantations

Industrial forest plantations are playing an increasingly important role in meeting world wood requirements. Recent successes with plantations in the tropics and Southern Hemisphere suggest potential for considerable expansion. The results of a detailed investigation of the comparative economics of industrial forest plantations in twelve regions of the globe, including nine in the tropics and Southern Hemisphere, are reported. The important factors are identified and discussed and formal investment criteria are applied. In general, the analysis suggests that the economics of plantation forests in the regions of the Southern Hemisphere examined are quite favorable, provided that the development costs, which may be substantial, can be adequately covered.     

Spatial heterogeneity of dead fuel moisture content in a Larix gmelinii forest in Inner Mongolia using geostatistics

Spatial heterogeneity of fuel moisture content determines the spread rate and direction of a forest fire.Research on the spatial heterogeneity of the moisture content of dead fuel of Larix gmelinii Rupr.showed that:(1) fuel moisture content in litter layer semi-humus layer humus layer,and the coefficient of variation decreased with sampling depth;(2) the sill value of the semi-humus layer was highest,the humus layer moderate,the litter layer the smallest,overall,the spatial heterogeneity of the semi-humus layer was the highest.The humus layer in the slant direction and three layers in a vertical direction showed strong spatial correlation with the lowest nugget coefficient of 0.0968;(3)the fuel moisture content of the humus layer showed strong spatial anisotropy;and,(4) estimating the total moisture content of the sampling site by stimulated sampling reasonable control of the sampling interval,and increasing the sampling intensity can reduce the error.When the sampling intensity is increased to more than 16 and the sampling interval 3 m,the standard error is 15%.The spatial heterogeneity of fuel moisture content is best revealed by increasing sampling density,sampling in different fire seasons,and in different slope directions and positions.The results can provide a scientific basis for forest fire prediction and prevention.     

Ideal Point Method Applied in Forest Harvest Regulation

IDttoductionl'I'lSuPposingthereare111objechvef(x).f(x),...Jm(x),eachobjechvehasifsoph111alsoluhonorophmalvaluefIfforl,2,--.,m,oneofanyvaluesistakenin111se-ries,.(i)willbesame,itisx',thenx=x',everyobjechvemcyreachitsOPtimalPOint.Infact,itisverydifficulttor…     

Industrial forest plantations in Uganda: Local adjacent community perspectives

Industrial forest plantations are both hailed and vilified for their socio-economic effects on local communities. As such, we posed the following questions: (1) what opportunities do industrial forest plantations bring to local communities? and (2) what benefits are lost with the establishment of industrial forest plantations?

Households neighboring industrial forest plantations in five villages of mid-western Uganda were surveyed. A large majority of the respondents (92.6%) stated that they had benefited from forest plantations, while a minority (7.4%) stated they did not. Fuelwood and employment were the most mentioned benefits. Approximately 47.9% of respondents stated that they had lost certain benefits due to the establishment of industrial forest plantations, while 52.1% stated they lost no benefits. Occupation, the number of people in a household and the length of residence in the area influenced responses on whether participants had lost certain benefits.

Access to land was the most mentioned (82.2%) benefit lost due to industrial forest plantations. The study supports the notion that industrial forest plantations can provide certain benefits in the initial years of establishment but may also deny local communities historically established customary access and user land rights. Local livelihoods should be integrated into forest plantations management plans.     

Working time design for industrial forest plantations in East Kalimantan

The objectives of this study were to clarify physiological loads under tropical conditions and to establish a proper working time design for tropical forestry operations. The research was conducted in East Kalimantan, Indonesia, in 1995. In this research, physiological loads and thermal conditions were investigated under various conditions,i.e., in forests and nurseries, on roads and at logged-over areas. Using the standards of the American Conference of Governmental Industrial Hygienists (ACGIH), a structure of work to rest proportions could be designed properly. Results showed that felling and cutting trees and weeding in the forest could be done continuously early in the morning and with 25% rest time for the remainder of the work day. Spreading fertilizer at the nursery could be done almost continuously all day. Road maintenance could be performed continuously during early morning but 50–100% rest time was needed for the remainder of the day. At logged-over areas, path clearing using chainsaws and soil hoeing required 50% rest early in the morning and 75–100% rest after that time, while planting required 25% rest early in the morning and 50–100% rest after that time. In conclusion, work done at logged-over areas required a greater percentage of rest time than work at other locations except early in the morning. A part of this paper was orally presented at the 107th Annual Meeting of the Japanese Forestry Society (1996). Corresponding author.     

Conservation value of forest plantations for bird communities in western Kenya

Tree plantations of native and exotic species are frequently used to compensate for forest loss in the tropics. However, these plantations may support lower species diversity and different communities than natural forest. We therefore investigated bird communities in stands of natural forest, different types of tree plantations and secondary forest in Kakamega Forest, western Kenya. We compared birds differing in habitat specialisation, i.e. forest specialists, generalists, and visitors. We recorded significant differences in mean species richness and number of individuals among the different forest types. Stands of natural forest and plantations of indigenous tree species comprised more species and individuals than plantations of exotic tree species and secondary forest. This was caused by a significant decline of forest specialists and generalists from natural forest and indigenous plantations to exotic plantations and secondary forest. Species composition of the bird communities did not differ between natural forest stands and plantations of a mixture of indigenous tree species, but clearly changed between natural forest and plantations of single tree species. These findings demonstrate that natural forest areas are needed for the conservation of forest bird diversity, but that plantations with a mixture of indigenous tree species can have similarly high conservation value.     

林木蒸腾耗水研究综述

在阅读了大量文献的基础上,系统的阐述了研究林木蒸腾耗水的意义,综述了林木蒸腾耗水研究的主要方法及应用条件,重点介绍了林木水分传输机理与耗水调控机制和林木蒸腾耗水性的研究状况。     

Crop production on soil under some forest plantations in the Sahel

The production of maize (Zea mays L.), guinea corn (Sorghum vulgare L.) and groundnuts (Arachis hypogea L.) grown in pots on soils sampled under neem (Azadiracta indica A. Juss), Eucalyptus camaldulensis Dehnh, and Prosopis juliflora Swartz, plantations in the Sahel region of Nigeria was investigated. Ordinary field soil adjacent to the plantation formed the control against which forest and species effects on the soil were compared.Crops, particularly maize and sorghum, produced higher dry matter on forest influenced soil than on ordinary field soil. The leguminous groundnuts however, appeared to have fixed its own nitrogen and therefore depended less on the inherent fertility advantages of the forest soil. The highest crop yield was obtained on the soil under neem followed by Prosopis, Eucalyptus and ordinary field. Since forest species differed in their effects on crop yield, further indentification, categorization and development of species with positive effects on crop yield was suggested for priority attention.     

Soil nitrogen status of larch plantations in comparison with secondary broad-leaved forest

IntroductionSoildegradationofsouthernChinesefir(CunnhaamialanceolaIe)pIantationshavebeenCon-tinuaIlyreiorted(ShenWeitongl992;Che11BingI1aol992;FangQil992).lnthenortI1eastforestregionsofChina,larch(LarirohensisandLa)`ixgInelinii)planta-tionsmade7opercentoftheman-madeforests,andthechangesinsoilpropertiesundertI1econiferouspIanta-tionshavealsodrawnmuchattentionofmanyforesters.OurobjectivewastoexaminethedifferenceinsoilnitrogenstatusbetweenLarchp1antatiol1sandsecon-darybroad-Ieavedforests(…     

长白落叶松人工林地森林土壤水分规律的探讨

文章根据新宾城郊林场长白落叶松人工林的不同生长期林地水分变化规律,描述了林地土壤的水分变化动态,可供从事长白落叶松造林和经营参考。     

Diversity of naturally-regenerated native woody species in forest plantations in the Ethiopian highlands

Woody species diversity and ground layervegetation cover were studied in plantations ofPinus patula, Cupressus lusitanica,Grevillea robusta, and Juniperusprocera, and in surrounding natural forests inWondo Genet, Ethiopia. In the understory of theplantations, a total of 53 naturallyregenerated tree and shrub species belonging to31 families were recorded. Important indigenoustimber species were also represented. Treesaccounted for 72% of all naturally-regeneratedwoody plant species. On the average, 78% ofthe woody species found in plantations werealso found in the natural forest. There was nosignificant variation in understory woodyspecies richness among plantations. C.lusitanica plantations had a significantlyhigher abundance of woody species than those ofP. patula, but the difference wasnot significant in relation to J. procera,G. robusta and the adjacent natural forest.The herbaceous ground cover percentage in G. robusta and P. patula stands wasconsiderably higher than in C. lusitanicaand J. procera stands. Relative toplantations of other species, plantations ofthe native tree species J. procera hadhigher understory species richness, mediumwoody species abundance and low ground cover.Although there was a marked variation inoverstory plantation density, its effect onunderstory species richness and abundance wasnot significant. The density ofnaturally-regenerated woody species inplantations was over three times the usualplanting density in Ethiopia, indicating a highpotential of forest plantations for restoringthe natural forest ecosystems on degraded landsat a comparatively low cost.     

关于加强营造林工程管理全面提高工程建设质量的思考

国家实施生态环境保护和建设“林业六大工程”，给贵州省林业生态环境保护和建设带来了千载难逢的历史机遇。由于历史原因，贵州省的林业管理水平较低，科技含量不高，监督体系不健全等等，也严重影响了营造林工程的建设质量。因此，我们必须紧紧抓住“林业六大工程”的实施，严格按照“严管林，慎用钱，质为先”的要求；以林业生态建设工程为切入点，强化工程管理，做到“六个突破”，实现“六个转变”，才能全面提高营造林工程的建设质量。     

Varying moisture content and eigen-stresses in timber elements

Abstract

The load-bearing capacity of timber elements and systems is affected by moisture exposure. Varying moisture content in the ambient air and resulting non-uniform moisture profiles on cross-sections generate stresses perpendicular to grain because of restraint of hygroexpansion. This paper presents effects of indoor moisture diffusion in timber elements; moisture profiles within member and corresponding stresses are determined using finite element analysis and a relevant constitutive model. The stress variability is larger near the surface compared with the middle of a cross-section. No major differences are noticed between different climatic locations, but the induced stresses reach high levels above the characteristic strength in tension perpendicular to grain. It appears that indoor moisture effects differ insignificantly between the different climatic locations investigated in this study.     

Large-scale,multi-year,phenology modelling of forest insects in Pinus radiata plantations

Journal of Pest Science - Ecologically and economically harmful wood borers and bark beetles, which have the capacity to expand geographically through the international log trade, require...     

Taking the pulse of forest plantations success in peri-urban environments through continuous inventory

Urban expansion increases the need for, and pressure on, green areas. Reforestation projects in the rural–urban fringe represent an opportunity for enhancing the environmental quality of peri-urban spaces and a means to contribute to cities carbon neutrality policies. Yet, relatively little information exists regarding the long term (10–25 years) survival and growth rate in urban and peri-urban plantations. This paper reports and discusses the results achieved by a reforestation in the peri-urban space of Rome (Italy), 25 years after its establishment. The plantation has been periodically surveyed between 6 and 24 years of age by means of continuous inventories, with the aim of monitoring growth dynamics. Permanent sample plots have been investigated and stratified by tree species composition (broadleaves vs. conifers, single vs. multispecies) for data analysis. On the whole, plantations show suitable results in terms of rate of growth, carbon storage and uptake, especially in coniferous and mixed stands. The average stand volume of the forest plantation, currently ranges from one-and-a third to one-and-a-half times the average values estimated for natural high forest stands of the same age and species groups at country level. The species groups exhibit differential growth patterns over the observed period, that are mainly due to differences in the ecological traits of the planted trees. Ten years after the establishment, the average annual value of carbon uptake in conifer and mixed species group exceeds 10 Mg CO₂ equivalent ha^?1 year^?1, a figure corresponding to 4 times the value of deciduous broadleaves (oaks and other species) and 1.5 times the value of evergreen oaks. Twenty years after the establishment, the average annual carbon uptake peaks to 25 Mg CO₂ equivalent ha^?1 year^?1 in the mixed species group, exceeds 15 Mg CO₂ equivalent ha^?1 year^?1 in the conifers, and ranks between 6 and 12.5 Mg CO₂ equivalent ha^?1 year^?1 in the groups dominated by broadleaved species. Overall with a surface area just under 300 ha, the carbon uptake level of the Castel di Guido reforestation allows to offset the 0.04% of CO₂ emissions of the city of Rome. Although the spatial coexistence of even-aged plantation blocks characterized by a range of ecological traits, is expected to ensure a more continuous carbon sequestration, being less susceptible to damage of any kind, the current lack of silvicultural management may also lead to degradation processes, by triggering e.g. fuel accumulation and, by consequence, forest fires. In this line, recommendations are provided in order to improve the ecological and functional efficiency of the investigated reforestation. The field experiment demonstrates, ultimately, the capability of the continuous forest inventory to take the pulse over several decades of tree species performance and carbon uptake levels in urban and peri-urban reforestations.     

Nutrient exports under different harvesting regimes in fast-growing forest plantations in southern Europe

In the humid and temperate areas of southern Europe, forest plantations are dominated by fast-growing species (Eucalyptus globulus, Pinus radiata and Pinus pinaster), which are grown on acidic soils with low reserves of available nutrients. In this study the amounts of nutrients exported from the plantations under different regimes and intensities of harvesting were evaluated and, on the basis of the results obtained, silvicultural management methods aimed at improving the nutritional status of the plantations were proposed. We found high ratios between nutrients exported by harvesting and those available in soil stores, indicating limitation for P, Ca and Mg over the long term, which is consistent with frequently found deficiencies of these nutrients. Current harvesting practices (removal of stem wood and bark) result in high rates of export of P, K, Ca and Mg, especially in eucalypt plantations, because of the high productivity and low nutrient efficiency of this species. Comparison of the amounts of nutrients exported by harvesting, with natural inputs (rainfall and weathering) and outputs (stream water), suggests that intensive exploitation of these plantations may result in negative budgets, especially if whole tree harvesting is carried out. The application of fertilizers containing P, Ca and Mg should be encouraged in all cases to favour the return of nutrients, especially where logging residues are extracted. The cost of harvesting in terms of nutrients can also be reduced by careful selection of the tree species planted and of the tree fractions harvested and by reducing the intensity of harvesting.