Soil Density

Tropical peatlands form in at least two distinct altitudinal zones, namely lowlands and high mountains. Unlike lowland tropical peatlands, which are typically forested, tropical mountain peatlands are dominated by cushion plants, bryophytes and herbaceous plants. Tropical mountain peatlands are poorly understood and little information is available on their ages, whether their peat bodies are relicts or actively accumulating carbon, the amount of carbon they contain, or the rate at which they can accumulate carbon. Our objective in this paper is to quantify carbon accumulation rates in two peatlands in the Andes Mountains of Ecuador, South America. At each site, we collected peat cores which were analysed for bulk density, mineral content and % C and we calculated the amount of carbon stored. Due to the high amount of mineral sediment in the Cotopaxi peatland, carbon dating was not done at this site. The Cayambre-Coca peat body was 4 m thick, ca. 3,000 years old, and had accumulated 140 kgC m -2 . The approximate long-term rate of carbon accumulation (LARCA) is 46 gC m -2 yr -1 . However, a significant part of the depth of accumulation is due to high levels of mineral sediment input from steep side slopes and volcanic ash input.

Tropical peatlands form in at least two distinct altitudinal zones, namely lowlands and high mountains. Unlike lowland tropical peatlands, which are typically forested, tropical mountain peatlands are dominated by cushion plants, bryophytes and herbaceous plants. Tropical mountain peatlands are poorly understood and little information is available on their ages, whether their peat bodies are relicts or actively accumulating carbon, the amount of carbon they contain, or the rate at which they can accumulate carbon. Our objective in this paper is to quantify carbon accumulation rates in two peatlands in the Andes Mountains of Ecuador, South America. At each site, we collected peat cores which were analysed for bulk density, mineral content and % C and we calculated the amount of carbon stored. Due to the high amount of mineral sediment in the Cotopaxi peatland, carbon dating was not done at this site. The Cayambre-Coca peat body was 4 m thick, ca. 3,000 years old, and had accumulated 140 kgC m-2. The approximate long-term rate of carbon accumulation (LARCA) is 46 gC m-2 yr-1. However, a significant part of the depth of accumulation is due to high levels of mineral sediment input from steep side slopes and volcanic ash input.

The density of soil is crucial in engineering, construction, and research. Standard methods to determine density use procedures, equipment or expendable materials that limit their effectiveness in challenging field conditions. Some methods require burdensome logistics or have time requirements that limit their use or the number of tests that can be executed. A test method, similar to the sand-cone method, was developed that uses steel shot as the material to which a volume of soil is compared to calculate soil density. Steel shot is easily recovered and reused, eliminating the need for specialty sand and calibrated cones or containers, and allows rapid determination of the volume of displaced soil. Excavated soil also provides measurements of total mass and moisture content. Volume, mass, and moisture content are applied in simple calculations to determine wet and dry densities and unit weight of the soil. Proficiency in performing the test can be achieved with minimal training, and the required kit can be assembled for a reasonable cost. Field uses of the method in dry environments in a variety of soil types demonstrated that the method can produce repeatable results within 2% of the values of soil density determined by traditional methods, with advantages in logistics.

This study was done to evaluate the impact of pure Norway spruce stands on physical soil properties of top soil in comparison to mixed species stands on comparable sites. It was hypothesized that the¯at root system of spruce causes soil compaction, which would have a negative impact on the soil aeration and hydraulic properties and consequently on seedbed quality, as well as early tree growth and seedling establishment. Hence, this topic is important for forest restoration, especially converting secondary pure spruce stands to mixed species stands. Forty-eight sites (24 pairs pure spruce stand/mixed species stand) of different stand development stages (mature stage, pole stage) were selected on two different bedrock materials (Molasse, Flysch). Undisturbed soil cores were taken from 0±4 and 4±8 cm soil depth and the following soil parameters were determined: (total) bulk density, remaining ®ne soil bulk density, dry masses of coarse fragments, roots and forest¯oor, organic carbon content, total soil pore volume as well as macropore volumes (after free drainage for 24 h and after water desorption at 10 kPa). The remaining ®ne soil bulk density was a useful parameter for characterization of the state of compactness. Pure spruce stands caused a lower bulk density of the upper mineral soil due to lifting and loosening of the soil above the root system. Results of calculated macropore volumes after water desorption at 10 kPa were exactly conform with those obtained for the remaining ®ne soil bulk density, indicating signi®cant differences for the grouping variables bedrock material and species composition. It is concluded from this study that changes of soil physical properties of the upper mineral soil (0±8 cm soil depth) by Norway spruce will not reduce germination and growth of mixed species trees. However, chemical and nutritional changes were not subject of this study, which are expected to limit the success of forest restoration. #

The advancement of species poleward, due to global warming, has recently been documented worldwide. In Louisiana, Avicennia germinans (black mangrove) is moving northward into Spartina alterniflora salt marshes. Mangroves were historically restricted to southernmost islands and beaches by winter freezes; however, recently a noticeable expansion has occurred. The influence that mangroves have on ecosystem processes within Louisiana salt marshes has not been documented. Thus, this research examined the effects of mangrove expansion on sediment accretion, organic matter production and decomposition, and carbon assimilation, as well as edaphic parameters. Our results indicate that presently mangrove expansion has had no major effects on the ecosystem processes measured. Sediment accretion, belowground production, decomposition, and carbon assimilation were similar between Avicennia and Spartina. Where mangroves expanded into the surrounding salt marsh, elevation, redox potential, bulk density, and soil ammonium were slightly higher, while soil moisture and porewater salinity were somewhat lower. Because the mangroves are small in stature and areal extent, significant effects on ecosystem processes may presently be somewhat muted. However, if stands continue to grow, noted effects may occur in the future. Our research provides a baseline from which future ecosystem responses may be evaluated as mangroves in Louisiana continue to develop.

O presente trabalho teve-se como objetivo diagnosticar o uso atual das terras e suas implicações na variabilidade espacial dos atributos físicos densidade do solo (Ds), matéria orgânica (MO), frações texturais (areia, silte e argila) e argila dispersa em água (ADA), na bacia hidrográfica do Ribeirão Marcela, Região Alto Rio Grande, MG, através de técnicas de geoestatística, com a finalidade de observar padrões de ocorrência desses atributos na paisagem. Coletaram-se amostras de solo na camada de 0 a 0,15 m em malha, com intervalos regulares de 240 x 240 m (macroescala) e de 60 x 60 m (microescala), totalizando 165 pontos. A Ds apresentou-se com valores na faixa de 1,05 a 1,15 g cm -3 acima, portando, do valor característico para Latossolos (0,95 g cm -3 ), enquanto os maiores valores foram obtidos nas glebas sob pastejo. Os valores de MO variaram de 1,5 a 4,5 dag kg -1 , detectando-se maiores concentrações nas glebas sob eucalipto, cerrado mais denso e várzeas. As frações texturais variaram seguindo a rede de drenagem e a ADA indicou valores baixos ao longo de toda a bacia. Os mapas de krigagem mostraram-se importante no estudo e compreensão da variabilidade espacial de atributos físicos do solo na bacia hidrográfica, indicando áreas críticas de manejo.

Problem statement: It is important to investigate the seriousness of degradation of peat swamp forest caused by skidding system in terms of its function as a carbon sink. In this study, we formulated assumptions that conditions of our research site before the introduction of skidding system were in their natural states, thus that changes measured are clearly caused by skidding system. The objective of this study was to determine soil carbon storage of a tropical peat swamp forest in their natural state. Approach: Peat soil samples and bulk density were taken at 0-15 cm in a 0.3 ha plot at Sibu, Sarawak, Malaysia. The soil samples were analyzed for acidity, organic matter content, total carbon and total nitrogen. The humic acid extraction was also done and soil carbon storage values obtained by calculation. The calculation of carbon storage was by the bulk density method. Correlation analysis was used where applicable using Statistical Analysis System (SAS) version 9.1. Results: The results indicated that this tropical peat swamp forest rich in soil organic matter (97.645 %) but had extreme acidic environment (pH 3.737), thereby inhibiting organic matter decomposition rates. This tropical peat swamp forest also had large amounts of total carbon (48.823 %), low mineral nitrogen (0.896 %) and high C/N ratio (58.427). Stable carbon (soil carbon storage) positively correlated with unstable carbon (p<0.01, r = 0.43). The value of soil carbon storage was found to be 67.550 Mg Ha −1 (±61.49 % of unstable carbon). Furthermore, soil carbon storage positively correlated with soil organic matter (p<0.01, r = 0.43), total carbon (p<0.01, r = 0.43) and humic acid yield (p<0.01, r = 1.00). However, soil carbon storage negatively correlated with soil acidity (p<0.01, r = -0.55). Conclusion: From the results, it can be concluded that the tropical peat swamp forest indicates its specific natural state. This natural tropical peat swamp forest plays an important role as a sink rather than a source of carbon. The soil carbon storage in this natural tropical peat swamp forest was derived from unstable carbon and sensitive to soil acidity.

Urban agriculture is farming that is practiced in urban or periurban centers. Urban agriculture is a dynamic concept that comprises a variety of livelihood systems ranging from subsistence production and processing at household level to fully commercialized agriculture (Van den Berg and Van Veenhuizen, 2005). In addressing the complexities of land reform in the post-apartheid South Africa, the Government has made provision for the allocation of commonage land, largely peri-urban land, to poor residents in order to help with local economic development (South African Government, 2001). Mafikeng is the capital city of the North West Province with a population growing at a rate of 9.3%. According to the City Council of Mafikeng (1999), some farmers have been irrigating about 560 ha at 23 sites in the peri-urban areas of the city of Mafikeng since 1994. The agricultural activities of these farmers

A compacted soil is a sign of degradation of its soil physical properties that affect plant growth. The objective of this study was to evaluate the effects of biomass incorporation on soil compaction in a livestock farm. A Vertisol soil in Sincelejo (Sucre) was used. Soil physical properties such as texture, real density and bulk density, maximum densities of compaction and moisture content at maximum densities of compaction were assessed. Correlation analysis was used to determine the relationship between soil organic matter, maximum densities and soil moisture. A randomized complete block design, with three repetitions, was used to determine the soil maximum density and the critical soil moisture. A 2X4 factorial treatment arrangement design was used, with two types of biomass (dry and wet) and four amount of organic matter. The soil maximum density under natural conditions (without incorporation of organic matter) was 1,421 g cm-3 with soil moisture of 26,573%. When 20 Mg ha-1 of wet or dry biomass were added to the soil, the soil maximum density and soil moisture reached values of 1,406 g cm-3 and 28,074% and 1,379 g cm-3 and 26,833%, respectively. There was a significant difference between the amount and type of organic matter added to the soil related to the soil máximum density. Incorporation of biomass to the soil used in this study helped to decline the soil maximum densities and increased soil moisture

Tropical peatlands form in at least two distinct altitudinal zones, namely lowlands and high mountains. Unlike lowland tropical peatlands, which are typically forested, tropical mountain peatlands are dominated by cushion plants, bryophytes and herbaceous plants. Tropical mountain peatlands are poorly understood and little information is available on their ages, whether their peat bodies are relicts or actively accumulating carbon, the amount of carbon they contain, or the rate at which they can accumulate carbon. Our objective in this paper is to quantify carbon accumulation rates in two peatlands in the Andes Mountains of Ecuador, South America. At each site, we collected peat cores which were analysed for bulk density, mineral content and % C and we calculated the amount of carbon stored. Due to the high amount of mineral sediment in the Cotopaxi peatland, carbon dating was not done at this site. The Cayambre-Coca peat body was 4 m thick, ca. 3,000 years old, and had accumulated 140 kgC m -2 . The approximate long-term rate of carbon accumulation (LARCA) is 46 gC m -2 yr -1 . However, a significant part of the depth of accumulation is due to high levels of mineral sediment input from steep side slopes and volcanic ash input.

This study was done to evaluate the impact of pure Norway spruce stands on physical soil properties of top soil in comparison to mixed species stands on comparable sites. It was hypothesized that the¯at root system of spruce causes soil compaction, which would have a negative impact on the soil aeration and hydraulic properties and consequently on seedbed quality, as well as early tree growth and seedling establishment. Hence, this topic is important for forest restoration, especially converting secondary pure spruce stands to mixed species stands. Forty-eight sites (24 pairs pure spruce stand/mixed species stand) of different stand development stages (mature stage, pole stage) were selected on two different bedrock materials (Molasse, Flysch). Undisturbed soil cores were taken from 0±4 and 4±8 cm soil depth and the following soil parameters were determined: (total) bulk density, remaining ®ne soil bulk density, dry masses of coarse fragments, roots and forest¯oor, organic carbon content, total soil pore volume as well as macropore volumes (after free drainage for 24 h and after water desorption at 10 kPa). The remaining ®ne soil bulk density was a useful parameter for characterization of the state of compactness. Pure spruce stands caused a lower bulk density of the upper mineral soil due to lifting and loosening of the soil above the root system. Results of calculated macropore volumes after water desorption at 10 kPa were exactly conform with those obtained for the remaining ®ne soil bulk density, indicating signi®cant differences for the grouping variables bedrock material and species composition. It is concluded from this study that changes of soil physical properties of the upper mineral soil (0±8 cm soil depth) by Norway spruce will not reduce germination and growth of mixed species trees. However, chemical and nutritional changes were not subject of this study, which are expected to limit the success of forest restoration. #

Alterações estruturais causadas no solo pelos sistemas de manejo podem resultar em compactação e interferir no desenvolvimento radicular das culturas. Com o objetivo de avaliar os influxos do tipo de manejo sobre a estrutura do solo, por meio de métodos qualitativo (perfil cultural) e quantitativo (densidade), realizou-se um estudo em solo derivado do basalto, com textura argilosa a muito argilosa, no município de Maringá (PR), Terceiro Planalto Paranaense, coordenadas 23 ° 29 ' S e 51 ° 59 ' W, submetido aos sistemas de manejo convencional com sucessão de milho (Zea mays L.) e soja (Glycine max); e plantio direto com rotação de trigo (Triticum spp.), milho (Zea mays L.), feijão (Phaseolus vulgaris), aveiapreta (Avena strigosa) e soja durante 20 anos. Próximo desses locais, selecionouse área de floresta como testemunha. Amostras indeformadas foram coletadas a partir dos volumes homogêneos de solo, verificados na descrição do perfil cultural: duas amostras em solo sob floresta, duas em plantio direto e três amostras em solo com manejo convencional. A análise física associada às análises morfológicas das estruturas do solo para as profundidades de 0 a 20 cm e 20 a 40 cm permite concluir que: (a) o tipo de manejo do solo agrícola determina quantidades distintas de horizontes antrópicos; (b) a condição apresentada pelo volume estrutural infere a forma de exploração do solo pelas raízes; (c) os processos de compactação no solo sob manejo convencional ocorrem tanto em profundidade como em lateralidade;

A utilização intensiva de máquinas e implementos agrícolas no nordeste do estado de São Paulo tem contribuído para aumentar as áreas com problemas de compactação, provavelmente pela ausência de um cronograma de trabalho bem definido ou de modelos capazes de estimar a capacidade de suporte do solo. O trabalho foi desenvolvido em Guariba (SP), com o objetivo de avaliar a variabilidade espacial da resistência à penetração do solo, umidade e densidade do solo em um Latossolo Vermelho eutroférrico sob cultivo de cana-de-açúcar. Os solos foram amostrados nos pontos de cruzamento de uma malha, com intervalos regulares de 10 m, perfazendo um total de 100 pontos, nas profundidades de 0,0—0,2 e 0,2—0,4 m. O coeficiente de variação indicou baixa variabilidade para umidade e densidade do solo nas duas profundidades e alta para resistência à penetração do solo. Observou-se um grau forte de dependência espacial para todas variáveis, exceto para densidade do solo na profundidade de 0,2—0,4 m que apresentou grau moderado de dependência espacial. Os altos valores para a resistência à penetração e densidade do solo, principalmente na profundidade de 0,2—0,4 m, indicaram compactação nesta camada. Pequenas variações nas formas do relevo condicionam variabilidade diferenciada nos atributos físicos dos solos.

Problem statement: It is important to investigate the seriousness of degradation of peat swamp forest caused by skidding system in terms of its function as a carbon sink. In this study, we formulated assumptions that conditions of our research site before the introduction of skidding system were in their natural states, thus that changes measured are clearly caused by skidding system. The objective of this study was to determine soil carbon storage of a tropical peat swamp forest in their natural state. Approach: Peat soil samples and bulk density were taken at 0-15 cm in a 0.3 ha plot at Sibu, Sarawak, Malaysia. The soil samples were analyzed for acidity, organic matter content, total carbon and total nitrogen. The humic acid extraction was also done and soil carbon storage values obtained by calculation. The calculation of carbon storage was by the bulk density method. Correlation analysis was used where applicable using Statistical Analysis System (SAS) version 9.1. Results: The results indicated that this tropical peat swamp forest rich in soil organic matter (97.645 %) but had extreme acidic environment (pH 3.737), thereby inhibiting organic matter decomposition rates. This tropical peat swamp forest also had large amounts of total carbon (48.823 %), low mineral nitrogen (0.896 %) and high C/N ratio (58.427). Stable carbon (soil carbon storage) positively correlated with unstable carbon (p<0.01, r = 0.43). The value of soil carbon storage was found to be 67.550 Mg Ha −1 (±61.49 % of unstable carbon). Furthermore, soil carbon storage positively correlated with soil organic matter (p<0.01, r = 0.43), total carbon (p<0.01, r = 0.43) and humic acid yield (p<0.01, r = 1.00). However, soil carbon storage negatively correlated with soil acidity (p<0.01, r = -0.55). Conclusion: From the results, it can be concluded that the tropical peat swamp forest indicates its specific natural state. This natural tropical peat swamp forest plays an important role as a sink rather than a source of carbon. The soil carbon storage in this natural tropical peat swamp forest was derived from unstable carbon and sensitive to soil acidity.

Soil compaction issue is a growing limiting factor for agricultural production. Progress in technology and agriculture, launched a long-term trend of soil destruction as a result of compaction. Th e experiment placed on Stagnic Luvisols will try to provide an assessment of the impact of tillage system on soil compaction. Th e aim of this study was to determine the optimal tillage system due to the compaction of individual horizons. For that reason fi eld experiment with six soil tillage systems was set up in Central Croatia. Tillage systems diff ered in tools that were used, depth and direction of tillage. During 2012 information of soil resistance, bulk density and soil porosity was collected. Statistical data evaluation showed signifi cant diff erences in bulk density and porosity in most of the soil layers between all tillage systems. Bulk density values at all depths of all tillage systems varied in ranges of 1.47-1.69 g cm-3. Soil porosity showed signifi cant diff erence between all tillage systems in surface and deepest soil layer. Values ranged between 38.18 and 47.19%. Soil resistance showed signifi cant diff erences in most of the soil layers between all tillage systems. Th ere were no signifi cant diff erences in soil resistance between soil layers during dry (August) and wet (December) periods in layers up to 30 cm. It can be concluded that diff erent tillage practice signifi cantly aff ected soil resistance in most of the soil layers during the year, except in periods of the highest precipitation surplus and defi cit.

Forest soil is an important component of the natural environment, and is a primary medium for many biological activities. In this study, soil loss and displacement by excavator and bulldozer (heavy equipments) were measured on cut and fills slopes of forest roads located in Mazandaran province, Iran. The volumes of soil losses were estimated by prismoidal analyses of cut and fill slopes deformation between two time treatments (under subgrading and two years later) in slope classes of 30-50% and 50-70%. Weights of soil losses were calculated by multiplying the volumes of soil losses (cm 3) to the general bulk density (1.3g/cm 3). Soil displaced area by heavy equipment was evaluated according to earth working width. Results indicated that heavy equipment has significant effect on deformation of cut slope gradient and fill slope length (p<0.0001). During the two-year period, the cut (p<0.0002) and fill (p<0.0001) slope gradients were significantly deformed in different slope classes. The average soil loss by excavator and bulldozer were 160.35 t/ha yr and 429.09 t/ha yr, respectively. Moreover, the soil displaced area during the subgrading process by bulldozer was greater than excavator in both two slope classes (p<0.05). Soil loss and displacement in forest roads can be reduced by applying powerful excavators in subgrading project, especially in steep terrains.

To evaluate the long-term effect of wastewater application on soil physical properties, two treatment sites, close to Taupo and Levin, New Zealand, and non-irrigated control sites were compared. The soil at Taupo was a silt loam and has received wastewater application for 12 years. The soil at Levin is a sand, and has been wastewater irrigated for 22 years. The disposal blocks at both sites had a higher pH, a higher organic matter (OM) content, a lower bulk density, and thus higher total porosity, but a lower macroporosity than the control sites. The disposal block at the Levin site showed a higher hydrophobicity than the control block, which coincided with the higher soil carbon. In contrast, the Taupo soil showed a higher hydrophobicity at the control site, the site with the lower OM content. Long-term wastewater irrigation resulted in a higher aggregate stability, and changes of the total porosity following stress application were lower, suggesting higher internal soil strength. The hydraulic conductivity close to saturation was also higher in the disposal blocks. The soil mechanical strength, as determined by the precompression stress value was, however, slightly lower in the disposal blocks and not correlated with the aggregate stability.

The advancement of species poleward, due to global warming, has recently been documented worldwide. In Louisiana, Avicennia germinans (black mangrove) is moving northward into Spartina alterniflora salt marshes. Mangroves were historically restricted to southernmost islands and beaches by winter freezes; however, recently a noticeable expansion has occurred. The influence that mangroves have on ecosystem processes within Louisiana salt marshes has not been documented. Thus, this research examined the effects of mangrove expansion on sediment accretion, organic matter production and decomposition, and carbon assimilation, as well as edaphic parameters. Our results indicate that presently mangrove expansion has had no major effects on the ecosystem processes measured. Sediment accretion, belowground production, decomposition, and carbon assimilation were similar between Avicennia and Spartina. Where mangroves expanded into the surrounding salt marsh, elevation, redox potential, bulk density, and soil ammonium were slightly higher, while soil moisture and porewater salinity were somewhat lower. Because the mangroves are small in stature and areal extent, significant effects on ecosystem processes may presently be somewhat muted. However, if stands continue to grow, noted effects may occur in the future. Our research provides a baseline from which future ecosystem responses may be evaluated as mangroves in Louisiana continue to develop.

The objective of this study was to evaluate the impact forest plantations on physical, chemical and microbiological attributes a cerrado Oxisol. Soil samples were collected at 0–10 cm depth from sites cultivated with pinus (Pinus tecunumanii), eucalyptus (Eucalyptus grandis) and carvoeiro (Sclerolobium paniculatum) for over 20 years. An adjacent native cerrado area was used as a reference of the original soil conditions. It was observed in relation to the native cerrado: increases in soil density under pinus and eucalyptus, reduction in the macroporosity under pinus, lower organic matter contents under pinus and eucalyptus, besides decreases in the soil pH and in the base saturation under pinus and carvoeiro along with an increase in aluminum saturation. Soil microbial biomass carbon under the pinus, eucalyptus and carvoeiro sites was about half of that found under cerrado. The activities of acid phosphatase and arylsulfatase were inhibited by pinus and stimulated by carvoeiro. Among the forest systems evaluated, pinus promoted the greatest reduction on soil quality. The microbiological variables were the most sensitive to detect the effects of these systems on soil quality.

The research work was conducted on eroded soil (Missa Series) in Samarbagh, District Lower Dir to determine the effect of slope position on soil physico-chemical properties. Soil samples were collected from top-slope, midslope and bottom slope positions at horizon-A, B and C. Results showed a significant difference among the physicochemical properties of top, mid and bottom slope soils. Bulk density of the top-slope (1.51 g cm-3) was the highest followed by mid (1.39 g cm-3) and bottom slopes (1.32 g cm-3). Conversely, electrical conductivity EC-2.47 dS m-1), phosphorus (3.40 mg kg-1), Potassium (118.8 mg kg-1), Organic matter content (1.52 %), clay content (20.39 %) and silt content (49.17%) were the highest at bottom slope followed by mid and top-slopes, respectively. Soil A, B and C horizons were also significantly (p<0.05) different in their physico-chemical properties. Mean values showed that horizon Ap had the highest bulk density (1.43 g cm-3) and lower electrical conductivity (1.74 dS m-1), phosphorus (2.29 mg kg-1), potassium (84.86 mg kg-1), organic matter (1.08%), clay (12.83%) and silt content (40.49%) than both the B and C horizons. The deterioration in physico-chemical properties of top slope as compared to mid and bottom slopes and that of Ap horizon as compared to B and C horizons were presumed to be due to past soil erosion effect that removed the finer soil particles including soil organic matter and other plant nutrients. This study concluded that increasing extent of erosion due to slope effect can further deteriorate soil properties. The control of such damaging effects would require soil conservation strategies such as proper land levelling, afforestation, terracing and inclusion of restorative crops in cropping systems on these lands.

Soil properties can be affected by heavy equipment used for skidding but these impacts vary greatly with site conditions and operational practices. We assessed the effects of ground-based skidding on site disturbance and soil physical properties. We also tested the effects of skid trail slope and traffic frequency on soil compaction, total porosity, and moisture content. On average, about 30% of all harvested area was disturbed to varying levels. Intact forest floor (undisturbed) and light slash were the dominant surface conditions, covering an average of 68.9% of harvested area. Deep disturbed soils accounted for only just over 1.1% of observations. Results showed that dry bulk density, total porosity and moisture content were affected considerably on skid trails by traffic frequency and skid trail slope. Measurements of soil properties in the surface layer (0&ndash;10 cm) showed that bulk density is 57% higher and total porosity is 31% lower on the skid trail compared to the undis...