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Combined effects of soil texture and machine operating trail gradient on changes in forest soil physical properties during ground-based skidding

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Pedosphere 2020年第4期30卷 508-516页

作者： Ramin NAGHDI Ahmad SOLGI Eric R.LABELLE mehrdad nikooy Department of Forestry Faculty of Natural ResourcesUniversity of GuilanSowmeh Sara 1144(Iran) Technical University of Munich Hans-Carl-von-Carlowitz-Platz 2Freising 85354(Germany)

Wood extraction by heavy machinery has always been associated with soil disturbance in mountain forests,and the degree of soil degradation is influenced by several factors,including site and soil characteristics,soil moisture,type of equipment used,and number of machine *** effects of ground-based skidding operations on the physical properties of soils with different texture were evaluated at different levels of traffic frequency and trail gradient at two sites in an Iranian temperate *** treatments included combinations of three different traffic frequencies(3,8,and 14 passes of a rubber-tired cable skidder),three levels of trail gradient(20%) and two soil texture classes,clay loam(Site 1) and sandy loam(Site 2).The average gravimetric soil moisture at the time of skidding was 23%(Site 1) and 20%(Site 2).The average dry bulk density and total porosity of the undisturbed soil(control) were0.71 g cm-3 and 73.3% at Site 1(clay loam) and 0.86 g cm-3and 59.1% at Site 2(sandy loam),*** site 1(fine-textured soil),rutting began after three passes of the skidder,whereas at site 2(coarse-textured soil),rutting occurred only after eight *** of the traffic frequency and trail gradient,machine impact on the fine-textured soil caused greater increases in bulk density and rut depth compared to that on the coarse-textured *** three skidder passes and independent from trail gradients,dry bulk density at Site 1 increased by 54.8% compared to that of the undisturbed control,and the increase was 45.5% at Site ***,medium to fine-textured soils are more susceptible to compaction than coarse-textured *** soils,especially when moist,should be protected using brush mats created from harvesting residues during the forest processing phase.

关键词： bulk density forest processing rutting soil compaction soil disturbance soil type total porosity

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Snow damages on trees of an uneven age in mixed broadleaf forests:effects of topographical conditions and tree characteristics

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Journal of Forestry Research 2019年第4期30卷 1383-1394页

作者： Farzam Tavankar Angela Lo Monaco mehrdad nikooy Rachele Venanzi Amireslam Bonyad Rodolfo Picchio Department of Forestry Khalkhal BranchIslamic Azad UniversityKhalkhalIran Department of Agriculture and Forest Sciences(DAFNE) Tuscia UniversityVia S.Camillo de Lellis01100 ViterboItaly Department of Forestry Faculty of Natural ResourcesUniversity of GuilanSomehsaraIran

Snow damage on natural stands is an important problem concerning mountainous forest *** the present research,the frequency and intensity of heavy snow damage on natural stands and the relationship of damages with characteristics of trees,stand and topography were studied in mountainous forests of northern Iran.A systematic sampling design was applied to the study area(140 ha),with 122 circular *** grid dimension was100 m and each plot area was 1000 m^*** four types of snow damage to trees include:crown damage(8.6%),stem breakage(5.4%),uprooting(3.2%),and bending(1.4%).The frequency of crown damage grew with an increase inthe diameter at breast height(DBH),while the frequency of stem breakage,uprooting and bending decreased with an increase the *** frequency of crown damage,stem breakage,and total damages was related to tree species(p<0.01).Not all tree species were equally susceptible to snow *** amount of damage grew with increasing elevation and slope angle and decreased with increasing soil *** trees(DBH<25 cm)were more susceptible to snow damage than other *** damage decreased by as the trees in the stand became more mixed in *** susceptibility of trees to snow damage increased by height and slenderness *** adequate silvicultural operation,snow damage can be reduced to a minimum level in these natural forests.

关键词： Mixed forest Slenderness coefficient Snow damage Stem breakage Uprooting

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