Soil fractal features of typical forest stands in Jinyun Mountain, Chongqing City, Southwest China

In order to explore the forest soil physical property in the Three Gorges Reservoir areas, the fractal theory was adopted to study the soil fractal features of the four typical forest stands (mixed Pinus massoniana-broadleaf forests, evergreen broadleaved forests, Phyllostachys pubescens forests and evergreen broadleaved shrub forests) in Jinyun Mountain, Chongqing City, and they were compared with arable land. It has been proposed that the model can be used for the analysis of the relationship between the fractal dimensions and the properties of forest soil. The impacts of fractal dimensions on the soil properties were analyzed with the elasticity analysis and marginal yield analysis. Results showed that the fractal dimension of particle size distribution (PSD), the micro-aggregate size distribution (ASD) and the soil pore size distribution (SPD) can be used as the indices to evaluate the soil structure. In the typical stands of Jinyun Mountain, the fractal dimension of PSD is 2.7–2.9, the ASD is 2.5–2.8, and the SPD is 2.3–2.8. The soil structure of evergreen broadleaved shrub forests performed best in PSD, ASD and SPD, and the soil of P. pubescens forests is the worst. There were some relationships among the PSD, ASD, SPD and some soil properties in the different forests and farmland. The related coefficients are over 0.5. Based on the elasticity analysis and marginal yield analysis, the effect of PSD was more than those of ASD and SPD. Obviously, the further study on the fractal theory application in soil structure and soil properties has important significance. __________ Translated from Science of Soil and Water Conservation, 2006, 4(4): 39–46 [译自: 中国水土保持科学]     

Soil fractal features of subalpine coniferous forests in western Sichuan under different anthropogenic disturbances

Fractal theory, used to study natural figures and images with self-similarity but without characteristic lengths, offers an effective tool to investigate quantitatively the complex systems such as soil. In this paper, we have discussed about our study of the fractal features of the subalpine coniferous forests, soil particles, and microaggregates under different intensities of anthropogenic disturbances in the Miyaluo area of west Sichuan and investigated the effects of the disturbances on the forest soils attributed to different fractal dimensions. The study introduces a new way to investigate the recovery and reestablishment of subalpine coniferous forests. __________ Translated from Chinese Journal of Ecology, 2005, 24(8): 878–882 [译自: 生态学杂志, 2005, 24(8): 878–882]     

Infiltration characteristics of water in forest soils in the Simian mountains, Chongqing City, southwestern China

Spearman rank-correlation analysis and grey relational grade analysis were used to study infiltration characteristics of water in different forest soils in the Simian mountains, Chongqing City. The results indicate that the soil bulk density, contents of coarse sand, and porosity of macropores were significantly correlated with saturated hydraulic conductivity. Porosity of macropores and contents of coarse sand were positively correlated with soil saturated hydraulic conductivity and soil bulk density negatively. Based on the initial infiltration rate, the stable infiltration rate, time required for infiltration to reach a stable state, and cumulative infiltration, all of which are crucial parameters determining soil infiltration capacity, the results of grey relational grade analysis showed that the grey relational grades of the different forest soils were listed from high to low as broad-leaved forest (0.8031) > Phyllostachys pubescens forest (0.7869) > mixed conifer-broadleaf forest (0.4454) > coniferous forest (0.4039). Broadleaf forest had the best ability to be infiltrated among the four soils studied. The square roots of the coefficients of determination obtained from fitting the Horton infiltration equation, simulated in our study of forest soils, were higher than 0.950.We conclude that soils of broad-leaved forests were the best suited for infiltration processes of forestry in the Simian mountains. __________ Translated from Journal of Soil and Water Conservation, 2008, 22(4): 95–99 [译自: 水土保持学报]     

Effect of conversion of farmland to forest or grassland on soil erosion intensity changes in Yanhe River Basin, Loess Plateau of China

Dynamic changes of soil erosion affected by conversion of farmland to forest or grassland in the Yanhe River Basin were analyzed based on the revised universal soil loss equation (RUSLE). The RUSLE variables were selected and calculated reasonably using the GIS technique. Results show that: 1) After the conversion of farmland to forest or grassland, soil erosion decreased greatly. Compared with soil erosion in period of 1986 to 1997, the soil erosion amount had been reduced on the average by 30.6% by 2000; 2) Of the different land uses, slope farmland, especially the steep slope land had the greatest impact on soil erosion. The conversion of forest or grassland was the main driving force for the reduction of soil erosion; 3) In the short term, soil erosion was mainly controlled by C-factor, implying that the adjustment of land use structure might be an effective approach to reduce soil erosion. __________ Translated from Science of Soil and Water Conversation, 2007, 5(4): 27–33 [译自: 中国水土保持科学]     

Hydrological effects of forest litter and soil in the Simianshan Mountains in Chonging, China

A preliminary study of the hydrological effects of forest litter and soils in the Simianshan Mountains was carried out. Results indicate that the annual accumulation of different forest litters is about 6.80–20.21 t/hm² and the maximum water carrying capacity ranges from 1.8 to 4.6 mm. Among them the water carrying abilities of the litter of Lithocarpus glabra and natural deciduous forests are larger than that of Pinus massoniana. A power function relationship exists between the accumulated water-carrying volume and time. An investigation of the physical properties shows that forest soils, to a depth of 1 m, have a powerful water-carrying ability, varying from 7.84 to 18.87 mm. Non-linear regression analysis shows that the soil infiltration rate is significantly correlated with time. __________ Translated from Journal of Beijing Forestry University, 2005, 27(1): 33–37 [译自: 北京林业大学学报]     

Affecting factors of preferential flow in the forest of the Three Gorges area, Yangtze River

In order to study the factors affecting preferential flow, a 2.9 m-long, 2.6 m-deep soil profile was dug in the Quxi watershed, Yangtze River. To analyze the influence of rainfall on preferential flow, the preferential flow process was observed when the rainfalls were recorded. Soil physical and infiltration characteristics were also measured to study their effect on preferential flow. The results showed that the rainfall amount that could cause preferential flow was over 26 mm. There are four types of rainfall in the Three Gorges area, namely gradually dropping rain, even rain, sudden rain and peak rain. Preferential flow process was found to be relevant to the rainfall process. It was determined that with different rainfall types, preferential flow appeared at different times, occurring first in peak rain, followed by sudden rain, gradually dropping rain, and then even rain. Preferential flow would appear when the rainfall intensity was over 0.075 mm/min. In the studied area, the coarse soil particles increased with the soil depth, and for the deeper soil layer, the coarse particles promote the formation of preferential flow. Preferential flow accelerates the steady infiltration rate in the 83–110 cm soil horizon, and the quickly moving water in this horizon also enhanced the further formation and development of preferential flow. __________ Translated from Journal of Soil and Water Conservation, 2006, 20(5): 28–33 [译自: 水土保持学报]     

Impact of land use on physico-chemical and hydrological properties of ustifluvent soils in riparian zone of river Yamuna,India

Land use influences physico-chemical and water transmission properties of soil, which ultimately determine the suitability of land for different purposes. In present study, impact of different land use (forest and agriculture) on selected physicochemical and hydrological properties of soil was evaluated and compared with a reference site (uncultivated ravinous wasteland). Land use influenced infiltration rate, bulk density, mean weight diameter of aggregates and plant available water of soils. After 25 years of plantation of forest species, soil organic carbon content increased by more than twofold and mean weight diameter of aggregates by 2- to 6-fold in comparison to reference site. Significant reduction in soil bulk density (4–18%) and increase in steady state infiltration rate (1.5–2 times) was observed under the forest land use system. Conversion of ravine to forest system resulted in significant improvement in moisture retention capacity of soil. Conversion of ravine landform to agriculture adversely affected the soil bulk density and infiltration rate. The study provided practical information regarding rehabilitation potential of different tree species (Prosopis juliflora, Leucaena leucocephala, Acacia nilotica and Azadirachta indica) that could be used for restoration of ustifluvent soil susceptible to gully erosion in the semi-arid region.     

Microelement contents of litter, soil fauna and soil in Pinus koraiensis and mixed broad-leaved forest

The Mn, Zn and Cu contents of litter, soil fauna and soil in Pinus koraiensis and mixed broad-leaved forest in Liangshui Nature Reserve of Xiaoxing’an Mountains were analyzed in this paper, results showed that the tested microelement contents in the litter, soil fauna and soil followed the order: Mn>Zn>Cu, but varied with environmental components, for Mn the order is soil>litter>soil fauna, for Zn is soil fauna>litter and soil, and for Cu is soil fauna>soil>litter. The change range of the tested microelement contents in litter was larger in broad-leaved forest than those in coniferous forest. Different soil fauna differed in their microelementenrichment capability, the highest content of Mn, Zn and Cu existed in earthworm, centipede and diplopod, respectively. The contents of the tested microelements in soil fauna had significant correlations with their environmental background values, litter decomposition rate, food habit of soil fauna, and its absorbing selectively and enrichment to microelements. The microelements contained in 5–20 cm soil horizon were more than those in 0–5 cm humus layer, and their dynamics differed in various horizons. __________ Translated from Chinese Journal of Applied Ecology, 2007, 18(2): 277–282 [译自: 应用生态学报]     

Influence of floods on natural riparian forests along the Ergis River, west China

The riparian forests along the Ergis River, west China, composed mainly of Salicaceae species, play an important role in eco-environment protection and sustainable development of local agriculture, stockbreeding, and social economy of the northern desert region of Xinjiang Uygur Autonomous Region. The study of the influence of floods on the natural riparian forests is imperative for the understanding of the successional process and the acceleration of conservation and restoration of forests. By investigating the relationship between floods and dispersal of seeds, sprouting, natural regeneration, the structure of the forests, and their current distribution, we conclude that: 1) the ripening and dispersal periods of Salicaceae species seeds overlap largely with flood occurrence periods, and the sprouting and natural regeneration of seeds depend greatly on flood events; 2) floods supply soil water and increase groundwater level of riparian land through flood irrigation and horizontal infiltration to maintain the normal growth of the riparian forests; 3) floods have a decisive influence on the structure, composition, and distribution pattern of riparian forests, and any disturbance in the water flow has a profound effect on these characteristics. Given these facts, some management measures for conservation and restoration of the riparian forests are proposed, including the establishment of riparian forest buffer belt, bank stabilization measures, and maintenance of flood protection. __________ Translated from Journal of Beijing Forestry University, 2006, 28(2): 46–51 [译自: 北京林业大学学报]     

Diversity of soil microorganisms in natural Populus euphratica forests in Xinjiang, northwestern China

To better understand the distribution of soil microorganisms in Populus euphratica forests in Xinjiang, northwestern China, we studied and compared the populations and numbers of bacteria, fungi and actinomycetes in the soil at four different age stages of natural P. euphratica forests, i.e., juvenile forests, middle-aged forests, over-mature forests and degraded forests. Results showed that there were clear differences in the amount of microorganism biomass and composition rates across the four forest stages. Dominant and special microorganisms were present in each of the four different soil layers. The vertical distribution showed that the microorganism biomass decreased with increasing soil depth. The population of microorganisms was the lowest at 31–40 cm of soil depth. The microorganisms consisted of bacteria, actinomycetes, as well as fungi. Bacteria were the chief component of microorganisms and were widely distributed, but fungi were scarce in some soil layers. Aspergillus was the dominant genus among the 11 genera of fungi isolated from the soil in different age stages of P. euphratica forests. __________ Translated from Journal of Beijing Forestry University, 2007, 29(5): 127–131 [译自: 北京林业大学学报]     

Effects of site conditions and methods of cultivation on growth of sawtooth oak plantations

The effects of site conditions and cultivation on the growth of sawtooth oak (Quercus acutissima Carr.) plantations were evaluated at the Hongyashan forest farm, in Chuzhou City, Anhui Province, China. The results indicate that the position on the slope, the amount of gravel and the thickness of the soil were important factors in the growth of the sawtooth oak. Lower slope positions with small amounts of gravel and a thick soil were better for the growth of this species than middle slope positions with more gravel and a thin soil. Given the site conditions of the hilly and mountainous areas in Chuzhou City, the mixed Chinese fir (Cunninghamia lanceolata Hook.) and sawtooth oak forests did not improve forest productivity compared with pure sawtooth oak forests. Both urea and compound fertilizers promoted the growth of sawtooth oak, as did site preparation and intercropping. Two years after planting, the height growth of ordinary seedlings with a starting height of 0.6 m was higher than that of supper seedlings with a starting height of 1.0 m. Compared with planting, the early growth of the coppices was faster, but the later growth of the coppices was slower. __________ Translated from Journal of Fujian College of Forestry, 2008, 28(2): 130–135 [译自: 福建林学院学报]     

Division of afforestation site type in the watershed of Wangjiagou, West Shanxi through GIS

Using quantification theory I, an analysis of the relation of soil water and qualitative factors, such as, slope degree, slope aspect, slope position, and soil in Wangjiagou watershed area has been done. The study aims to quantify the factors influencing soil water, the descending order of the factors being the slope aspect, soil, slope degree, and slope position, thereby scientifically facilitating division of afforestation site types and afforestation site products digitally on geographical information system (GIS). __________ Translated from Journal of Northwest Forestry University, 2006, 21(3): 184–188 [译自: 西北林学院学报, 2006, 21(3): 184–188]     

Microenvironmental heterogeneity of physical soil properties in a broad-leaved Pinus koraiensis forest gap

Microenvironmental heterogeneity of soil physical properties in 0–20 cm and 20–40 cm soil layers in a broad-leaved Pinus koraiensis forest gap in Xiao Xing’anling Mountains were analyzed by geostatistical method. The results show that the amount of soil water, saturation water capacity, capillary water capacity and porosity in the top layer were greater than those in the lower layer, except for bulk density, where the opposite applied. Soil physical properties in the top soil layer had relatively higher ranges and coefficients of variation. The total and auto correlation spatial heterogeneity of soil physical properties in the top layer were larger than those in the lower layer. The soil water had a strong anisotropic structure in an easterly and northerly direction, but porosity shows isotropy in the same directions. With increasing spatial distance, the other three physical factors exhibited anisotropic structures. The mutual effect between semi-variograms of soil physical properties in the top layer within the spatial autocorrelation range was not significant. For spatial distribution of physical properties within different layers, the patches at the middle and lower ranks in the forest gap dominated. Patches at higher rank were only distributed in the 0–20 cm soil layer and were located north of the forest gap center. __________ Translated from Science of Soil and Water Conservation, 2007, 5(3): 52–58 [译自: 中国水土保持科学]     

Fractal features and infiltration characteristics of the soil from different land uses in a small watershed in a rocky,mountainous area in Shandong Province

We studied infiltration and fractal mechanisms on sloping farmlands in a small watershed in Shandong Province in the rocky mountain areas of northern China.We studied soil fraction and soil water retention curves,and developed a soil infiltration model to analyze its quantitative relationship with soil particle size and pore dimensions under four types of land use,including sloping farmland,abandoned land,natural forest,and forest plantation(Malus pumila,Crataegus pinnatifida).Soil stability infiltration rate ranked as sloping farmland>abandoned land>natural forest>forest plantation.The sequence of soil particle size and pore dimension ranked as natural forest>forest plantation>abandoned land>sloping farmland.There were significant positive correlations between soil particle size and pore dimension,and both were positively correlated with the percent volume of silt and clay.They were negatively correlated with soil infiltration rate.The Horton model and the power function model were more suitable for simulating soil infiltration and the infiltration rate.We concluded that the soil in this area displayed typical fragments of rocky mountainous regions due to the loss of silt and clay caused by cultivation on sloping farmland.The uniformity and fractal dimensions of soil particle sizes and pore distribution decreased,thereby enhancing soil infiltration capacity and decreasing soil water retention capacity.     

北京平原地区不同土地利用类型对土壤颗粒组成及其分形特征的影响

选取农田、撂荒草地、人工乔木林、人工灌木林和次生林5种不同土地利用类型土壤颗粒为研究对象,采用Microtrac S3500激光粒度仪测定土壤样品粒径,利用土壤分形学理论和方法,分析不同土地利用类型对土壤颗粒组成及其分形特征的影响。结果表明,土壤粒径在不同土地利用方式下存在显著差异,其中撂荒草地以砂粒为主,农田、人工乔木林、人工灌木林和次生林以粉粒为主;次生林、人工乔木林黏粒体积分数最大,且显著大于其他土地利用类型,撂荒草地最小;次生林、人工乔木林、人工灌木林粉粒体积分数最大,且显著大于农田与撂荒草地;砂粒体积分数则与粉粒相反。土壤分形维数的大小依次为撂荒草地＜农田＜人工灌木林＜次生林＜人工乔木林;土壤分形维数与土壤黏粒含量、粉粒含量均呈显著正相关,与土壤砂粒含量呈显著负相关。     

Effects of different vegetation restoration models on soil microbial biomass in eroded hilly Loess Plateau, China

Vegetation restoration is a key measure to improve the eco-environment in Loess Plateau, China. In order to find the effect of soil microbial biomass under different vegetation restoration models in this region, six trial sites located in Zhifanggou watershed were selected in this study. Results showed that soil microbial biomass, microbial respiration and physical and chemical properties increased apparently. After 30 years of vegetation restoration, soil microbial biomass C, N, P (SMBC, SMBN, SMBP) and microbial respiration, increased by 109.01%–144.22%, 34.17%–117.09%, 31.79%–79.94% and 26.78%–87.59% respectively, as compared with the farmland. However, metabolic quotient declined dramatically by 57.45%–77.49%. Effects of different models of vegetation restoration are different on improving the properties of soil. In general, mixed stands of Pinus tabulaeformis-Amorpha fruticosa and Robinia pseudoacacia-A. fruticosa had the most remarkable effect, followed by R. pseudoacacia and Caragana korshinkii, fallow land and P. tabulaeformis was the lowest. Restoration of mixed forest had greater effective than pure forest in eroded Hilly Loess Plateau. The significant relationships were observed among SMBC, SMBP, microbial respiration, and physical and chemical properties of soil. It was concluded that microbial biomass can be used as indicators of soil quality. __________ Translated from Journal of Natural Resources, 2007, 22(1): 20–27 [译自: 自然资源学报]     

Spatial distribution characteristics of fine roots of Populus euphratica in a desert riparian forest

The soil-plant system is a very important subsystem of the soil-plant-atmosphere continuum (SPAC). The water uptake by plant roots is an important subject in the research on water transport in this SPAC and is also the most active study direction in the fields of ecology, hydrology and environment. The study of the spatial distribution pattern of fine roots of plants is the basis of constructing a water absorption model of plant roots. Our study on the spatial distribution pattern of fine roots of Populus euphratica in a desert riparian forest shows that the density distribution of its root lengths can be expressed horizontally as a parabola. The fine roots are concentrated within the range of 0–350 cm from the tree trunk and their amount accounts for 91.9% of the total root mass within the space of 0–500 cm. In the vertical direction, the density distribution of the fine root lengths shows a negative exponential relation with soil depth. The fine roots are concentrated in the 0–80 cm soil layer, accounting for 96.8% of the total root mass in the 0–140 cm soil layer. __________ Translated from Chinese Journal of Ecology, 2007, 26(1): 1–4 [译自: 生态学杂志]     

Effect of forest vegetation on runoff and sediment production in sloping lands of Loess area

According to fixed-position data for 1985–2003 from nine runoff plots of Caijiachuan watershed which lies in Jixian County of Shanxi Province in Loess area, this paper studied the relationship between vegetation and runoff and sediment production in sloping lands in detail, which helps to provide scientific basis for vegetation re-construction and studies on environmental transformation of water and sediment in watersheds of Loess area. Although, many study results testify that forest vegetation has an important function in soil and water conservation and cutting runoff, the effect of vegetation on runoff and sediment transmission is complicated, and this needs to be studied in depth. The results of the paper showed the following. Firstly, the natural secondary forest performs better function of soil and water conservation than artificial Robinia pseudoacacia forest, and runoff and sediment produced in the former in individual rainfall were 65%–82% and 23%–92% of those produced in the latter. At the same time, better correlative relationship between runoff and sediment production and rainfall and rainfall intensity were testified by multiple regression, but the correlation decreased gradually with the increase of canopy density of forest. Secondly, the difference of runoff and sediment production in several land use types was very distinct, and the amount of runoff and sediment produced from Ostryopsis davidiana forest and natural secondary forest were the least, and runoff and sediment produced from in artificial Robinia pseudoacacia forest and Pinus tabulaeformis forest were 5-fold as much as those from O. davidiana forest. Besides, runoff and sediment produced in mixed planting of apple trees and crops were 16.14-fold and 2.96-fold than those of O. davidiana forest, respectively, but the amount decreased obviously after high-standard soil preparation in the case of the former. Thirdly, based on gray cognate analyses of factors affecting runoff and sediment production in sloping land, the factors of stand canopy density and herb and litter biomass were the most significant ones, whose gray incidence degree exceeded 0.6. Therefore, mixed forest with multi-layer stand structure and shrub forest should be developed in vegetation re-construction of Loess area, which will help to increase coverage and litter thickness in order to cut down the runoff and sediment dramatically in sloping land. __________ Translated from Chinese Journal of Applied Ecology, 2005, 16(9): 1,613–1,617 [译自: 应用生态学报, 2005, 16(9): 1,613–1,617]     

Effect of tree-crop intercropping on a young Populus tomentosa plantation

In order to study the effect of tree crop intercropping on a young plantation of Populus tomentosa in the plains along the Yellow River, field experiments were conducted by observing the growth of the plantation, the nutrient content in leaves, the nutrient and water content in the soil, and the output of crops. The relationship between forest growth and nutrient content in the tree leaves and the soil were analyzed. Results show that tree crop intercropping in young plantations can not only improve soil water content, but also enhance the contents of organic matter and the available nitrogen, phosphorus and potassium in soil resulting in the vigorous growth of the individual trees. Diameter at breast height (DBH) was positively related to the contents of organic matter in the soil, and the contents of N, P and K in the tree leaves had correlation coefficients of 0.967, 0.955, 0.988 and 0.972, respectively. Whole tree leaf area, crown width, number of branches and the mean length of branches in the intercropped plantation (intercropped with watermelon and vegetables, peanut and winter wheat, and soybean) were, respectively, 1.70–3.0 times, 2.22–2.47 times, 1.0–1.41 times and 1.70–2.32 times of those of CK (without intercropping). Diameter at breast height (DBH) and tree height in the intercropped plantation were 50.5%–136.7% and 27%–59.5% higher than those of the CK, respectively. The study also showed that intercropping with watermelon and vegetables proved to have the highest economic return among the treatments adopted. Tree crop intercropping in young plantations is an effective measure to increase forest growth and economic benefit. __________ Translated from Journal of Beijing Forestry University, 2006, 28(3): 81–85 [译自: 北京林业大学学报]     

豫西石质丘陵区不同土地利用方式下土壤颗粒分形特征

运用分形理论,以豫西石质丘陵区土壤为供试材料,分析了天然次生林、荒草地、混交林、杨树林、耕地等5种土地利用方式的土壤颗粒分形特征及其与土壤各粒级含量、理化性质之间的关系。结果表明:1)研究区土壤细粒化较明显,具有一定的水土保持效应;2)5种用地方式分形维数平均值介于2.510～2.629之间,分维值大小依次为天然次生林>耕地>杨树林>混交林>荒草地,可以在一定程度上反映石质丘陵区水土流失的程度;3)土壤颗粒分形维数与土壤颗粒含量存在较强相关性,即土壤中黏粒含量越高,尤其是0.002～0.001 mm粒级含量越高,分形维数越大;4)研究区土壤颗粒分形维数与速效钾含量呈显著正相关,与其它理化性质的相关性均不明显。