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[Display omitted] • The first study to compare fine-textured Spodosols and podzolic Ultisols. • Clay coatings were observed in spodic horizons. • Nanocrystalline Fe oxides were deposited in podzolic Ultisols through episaturation. • Climate and landscape affected the differentiation of Spodosols vs podzolic Ultisols. Podzolization is considered to be facilitated by factors such as cool and humid climate, sufficient supply of certain types of organic acids, and coarse-textured parent materials. However, podzolic soils in subalpine areas in Taiwan are characterized by clay content higher than 30%, which differed from that in typical podzolic soils in temperate and boreal regions. This study examined the importance of factors controlling the differentiation of fine-textured podzolic soils in Taiwan. Samples from 31 pedons were examined in this study, and the pedons were grouped into four types, namely Spodosols, Ultisols, Inceptisols, and Inceptisols with placic horizons. Soil colors with 7.5YR 5/6 (the accumulation of spodic materials) and micromorphological observation of oriented clay coatings in the Spodosols confirmed the occurrence of podzolization and clay illuviation, and the selective extraction of Fe and Al confirmed that the Spodosols (Type I) had a higher accumulation of organometallic complexes than the other podzolic soils. A two-step mechanism, namely (1) clay illuviation at an early stage of pedogenesis and (2) podzolization after the canopy vegetation formed, was proposed for the formation of fine-textured Spodosols. Photomicrographs of the Ultisols (Type II) displayed clay hypocoatings masked by spodic materials, and argillic horizons were characterized by a high amount of nanocrystalline iron and high optical density of the oxalate extract. However, the accumulated nanocrystalline iron oxides in the Ultisols were due to the degradation of organic matter under high summer temperatures. Moreover, the leaching of iron in the albic horizons of the Ultisols was attributed to episaturation caused by high clay contents. The Inceptisols (Type III) were transitional soils before forming the Spodosols or the Ultisols, and high clay contents further induced episaturation and formed placic horizons in the Inceptisols (Type IV). Principal component analysis revealed that soil texture and precipitation were the main factors controlling the differentiation of podzolic soils in Taiwan. These factors determined the penetrability and leaching potential of soils, and only the coarse-textured soils with higher leaching potential had the chance of developing Spodosols. However, the developments of Ultisols and Inceptisols with placic horizons were controlled by air temperature and landscape, namely elevation and slope. The bleached E horizons in podzolic Ultisols were attributed to their flat landscape, which favored episaturation and caused the reduction of iron. Low elevation and high temperature in these regions also facilitated the degradation of organic matter and the accumulation of nanominerals. [ABSTRACT FROM AUTHOR]

Reducing nitrogen (N) leaching from croplands is important to protect environmental quality and improve recovery of applied N. To contribute to this broader goal of nutrient management, a simple pot experiment evaluated the potential differences among urea (250 kg N ha-1), urea+compost (125 kg N ha-1 from urea + 125 kg N from 8 Mg ha-1 of compost), compost (250 kg N from 16 Mg ha-1 of compost) and a zero control (Ctrl), in terms of their effects on apparent N recovery (ANR), mineral N (Nmin) leaching and soil retention of applied N. Cabbage (Brassica oleraceae L.) and corn (Zea mays L.) were grown in rotation where compost application was not repeated in the 2nd year. Nmin leaching was monitored by adding 83 mm and 62 mm of water fortnightly to cabbage and corn crops, respectively for a total of 28 times in a two-year period. Combined (urea+compost) and independent (compost) treatment application retained 1.5 to 2 times higher N, and lowered 2.1 to 4.6 times Nmin leaching, relative to independent (urea) application. We conclude that farmers' practice of fertilization that has an inherent problem of N leaching for high rainfall areas in Taiwan could be improved by proper compost and urea combinations within agronomically recommended rates of N application. [ABSTRACT FROM AUTHOR]

Abstract: The accumulation and effect of cadmium (Cd) on the growth and enzymatic activities changes of antioxidants in Tagetes patula, French marigold, were investigated to reveal the physiological mechanisms corresponding to its Cd tolerance and accumulation. Hydroponically grown T. patula plants were treated with different concentrations of Cd (0, 10, 25, 50μM CdCl2) at various regime of times. T. patula accumulated Cd to a maximum of 450mgCdkg−1 dry weight (DW) in shoot and 3500mgCdkg−1 DW in root after 14 days’ exposure at 10 and 50μM CdCl2, respectively. The translocation factors of Cd were greater than 1 in plants exposed to 10μM CdCl2. Toxic effects were gradually observed with increasing Cd concentration (25 and 50μM) accompanied with the reduction of biomass, chlorophyll content, decrease of cell viability and the increase level of lipid peroxidation. In leaves of T. patula, the activities of ascorbate peroxidase (APX), glutathione reductase (GR) and superoxide dismutase (SOD) were induced by Cd. However, in roots, activities of APX, GR, SOD and catalase (CAT) were significantly reduced by 25 and 50μM Cd treatment but not 10μM Cd. In-gel zymography analysis revealed that Cd induced the enzymatic activities of APX, MnSOD, CuZnSOD and different isozymes of GR in leaves. These results indicate that T. patula is a novel Cd accumulator and able to tolerate with Cd-induced toxicity by activation of its antioxidative defense system. [Copyright &y& Elsevier]

Soils contaminated with metals are a serious problem in central Taiwan; 70% of the metals-contaminated soils in Taiwan are distributed there. We used soil turnover and dilution methods to reduce the total concentration of metals in soil, but this technique may be not suitable for other sites because of their shallow soil depths, which were less than 60 cm. Central Taiwan has the largest flower market in Taiwan and we propose that using local flower species to clean up the metals-contaminated soils is a feasible solution. A 1.3-ha area contaminated by multiple metals (As, Cr, Ni, Cu, and Zn) located in central Taiwan was selected for this large-area phytoremediation experiment. According to the Taiwan Environmental Protection Administration project contract, in-situ selection experiments were conducted to select 12 potential species from 33 tested species for further large area experiment. After in-situ planting of 33 species of plants in the contaminated soil for 33 d, bougainvillea and cockscomb showed yellow-colored leaves and withered as the result of the toxicity of metals. Herbaceous plants can accumulate higher concentration of metals and have higher bioconcentration factor in relative to woody plants. Three weighting models of growth condition and the metal-accumulated concentration of plants growing in the site were evaluated and compared. Six woody plants and six herbaceous plants were selected as high potential metal accumulators for a further large-area experiment. [ABSTRACT FROM AUTHOR]

Abstract: Synthetic chelating agents are used to increase the phytoextraction of metals from contaminated soils, however the increased bioavailability of the metals may increases the potential risk of groundwater contamination. In this study, 4 mmol EDTA kg−1 was applied using four application methods to a Cd-, Zn-, and Pb-contaminated soil to evaluate the effects of multi-dose EDTA application on the metals concentrations in the soil solution, soil (as extracted by different methods), and shoots of rainbow pink (Dianthus chinensis). Results showed that application of 4 mmol kg−1 one time or application of 2 mmol kg−1 two times, significantly decreased the concentration of Cd, Zn, and Pb in the soil solution at the end of experiment (42nd day) compared with the application of 0.67 mmol kg−1 six times during 6 weeks experiments. Application of 2 mmol kg−1 two times significantly decreased the deionized water-extractable Cd and Pb concentrations in the soil compared with the application of 0.67 mmol kg−1 six times. However, there were no any effects of the different application methods on the concentration and total removal of Cd, Zn, and Pb in the shoots of rainbow pink. Results revealed that application of 2 mmol kg−1 two times was effective to decrease the potential groundwater contamination. [Copyright &y& Elsevier]

Abstract: Soil used in this study was artificially contaminated with Cd, Zn, Pb, or applied in combinations (Cd–Zn, Cd–Pb, Zn–Pb, or Cd–Zn–Pb) to study the interactions of metals in soil contaminated with multiple metals. After planting rainbow pink (Dianthus chinensis) in these soils for 21 days, three different concentrations of ethylenedinitrilotetraacetic acid (EDTA) solutions were added to study the effect of applying EDTA on the interactions among these metals. The concentrations of Cd, Zn, and Pb in the soil solutions of different metals-treated soils increased significantly after applying 5mmolEDTAkg−1 soil (p <0.05). The potential of groundwater contamination will increase after applying EDTA and it is not recommended to be in situ used or have to use very carefully. The existence of Pb in the Cd-contaminated soil enhanced the uptake of Cd in rainbow pink in the treatments of control and 2mmolEDTAkg−1 soil. Cadmium inhibited the concentration of Zn without applying EDTA. However, whether the application of EDTA or not and the applied EDTA concentration had the greatest effect on the uptake of Pb when compared to Cd and Zn. After applying 5mmolEDTAkg−1 soil, Cd or Zn in the Pb-contaminated soil inhibited the uptake of Pb in rainbow pink, but there were no effect in other treatments. [Copyright &y& Elsevier]

Abstract: Rainbow pink (Dianthus chinensis), a potential phytoextraction plant, can accumulate high concentrations of Cd from metal-contaminated soils. The soils used in this study were artificially added with different metals including (1) CK: original soil, (2) Cd-treated soil: 10mgCdkg−1, (3) Zn-treated soil: 100mgZnkg−1, (4) Pb-treated soil: 1000mgPbkg−1, (5) Cd–Zn-treated soil: 10mgCdkg−1 and 100mgZnkg−1, (6) Cd–Pb-treated soil: 10mgCdkg−1 and 1000mgPbkg−1, (7) Zn–Pb-treated soil: 100mgZnkg−1 and 1000mgPbkg−1, and (8) Cd–Zn–Pb-treated soil: 10mgCdkg−1, 100mgZnkg−1, and 1000mgPbkg−1. Three concentrations of 2Na-EDTA solutions (0 (control), 2, and 5mmolkg−1 soil) were added to the different metals-treated soils to study the influence of applied EDTA on single and combined metals-contaminated soils phytoextraction using rainbow pink. The results showed that the Cd, Zn, Pb, Fe, or Mn concentrations in different metals-treated soil solutions significantly increased after applying 5mmol EDTAkg−1 (p &#60;0.05). The metal concentrations in different metals-treated soils extracted by deionized water also significantly increased after applying 5mmol EDTAkg−1 (p &#60;0.05). Because of the high extraction capacity of both 0.005M DTPA (pH 5.3) and 0.05M EDTA (pH 7.0), applying EDTA did not significantly increase the Cd, Zn, or Pb concentration in both extracts for most of the treatments. Applying EDTA solutions can significantly increase the Cd and Pb concentrations in the shoots of rainbow pink (p &#60;0.05). However, this was not statistically significant for Zn because of the low Zn concentration added into the contaminated soils. The results from this study indicate that applying 5mmol EDTAkg−1 can significantly increase the Cd, Zn, or Pb concentrations both in the soil solution or extracted using deionized water in single or combined metals-contaminated soils, thus increasing the accumulated metals concentrations in rainbow pink shoots. The proposed method worked especially well for Pb (p &#60;0.05). The application of 2mmol EDTAkg−1 might too low to enhance the phytoextraction effect when used in silty clay soils. [Copyright &y& Elsevier]

Abstract: Three pedons of Inceptisols with placic horizons were selected to study the characteristics and genesis of subalpine forest soils located in Shang-Hsing Mountain in Ilan county, northeastern Taiwan. The selected pedons were elevated from 1900 to 2100 m and derived from slate formed in the late Quaternary age. The vegetation types are dominated by red cypress (Chamaecyparis formosensis Matsum) and Taiwan Chinese fir (Taiwania cryptomerioides Hay). The annual rainfall is about 3000 mm and mostly falls from April to October. The soil moisture regime is perudic, and the soil temperature regime is mesic. Three Inceptisols can be classified as Lithic Dystrudept and Oxyaquic Dystrudept based on USDA Soil Taxonomy or Cambisol based on World reference base system. Clear illuvial pedogenic processes were observed by the bleached albic (E) horizon and the underlain placic (Bs) horizons, which were characterized on the changes of soil morphology, micromorphology, soil texture and chemical compositions. The placic horizon appeared to be dominated by amorphous iron and free iron oxides, with lesser amounts of amorphous aluminum and free aluminum oxides. The genesis of the placic horizons in the study area was proposed as two stages. In the first stage, the perched water was located between albic horizon and cambic horizon after a storm owing to the texture changes of these two horizons. In the second stage, Fe of the upper part of the pedon was reduced, then be mobilized and reoxidized it in the boundary of E and Bw horizon. Therefore, the boundary of placic horizon has a wavy or irregular boundary. In addition, the genesis of placic horizon may also relate to the precipitation of mobile Fe at higher soil pH value and oxidizing soil contacts below the mineral soil surface. Although we do not find the argillic horizon formed below the placic horizon, Ultisols are a major soil order formed in the level landscape position of the study area. [Copyright &y& Elsevier]

The aspect and slope can control the movement of water and material in a hillslope and contribute to the spatial differences of soil properties. In a forest ecosystem, soil properties are also influenced by vegetation composition. The objectives of this study are to examine the characteristics and spatial differences of soil properties in a lowland evergreen broad-leaved rain forest in southern Taiwan, and to clarify the relationships between soil properties and the landscape. A total of 565 soil samples were taken at 0–5 and 5–15 cm in 74 contiguous 10×10-m quadrates along an altitudinal transect ranging from 300 to 480 m. The study transect was divided in three slope positions: summit, backslope and footslope positions, each with a different floristic composition and structure. Our study showed that organic carbon, available N, available K, extractable Fe and exchangeable Na were highest on the summit, while pH, available P, exchangeable Ca and Mg were significantly higher on the footslope at 0–5-cm soils. Similar patterns were observed at subsurface 5–15-cm depth soils. The OC increased with increasing altitude, probably due to the quality of litterfall and lower rate of decomposition in the summit forest. The results of redundancy analysis (RDA) also revealed clear separation of soil properties among slope positions. These results confirmed that slope factor involved in the transport and accumulation of solutes resulted in higher pH, exchangeable Ca and Mg, lower organic carbon, available N and K, extractable Zn in the depositional areas of footslope. Although the soil properties associated with landscape have been better understood, further studies are required to clarify the relationships between soil nutrient status and plants in Taiwan. [Copyright &y& Elsevier]

Rainbow pink (Dianthus chinensis), a potential phytoextraction plant, can accumulate high concentrations of Cd from contaminated soils. Vetiver grass (Vetiver zizanioides) has strong and long root tissues and is a potential phytostabilization plant since it can tolerate and grow well in soils contaminated with multiple heavy metals. Soil was moderately artificially contaminated by cadmium (20 mg/kg), zinc (500 mg/kg), and lead (1000 mg/kg) in pot experiments. Three concentrations of Na2–EDTA solution (0, 5, and 10 mmol/kg soil) were added to the contaminated soils to study the influence of EDTA solution on phytoextraction by rainbow pink or phytostabilization by vetiver grass. The results showed that the concentrations of Cd, Zn, and Pb in a soil solution of rainbow pink significantly increased following the addition of EDTA (p<0.05). The concentrations of Cd and Pb in the shoots of rainbow pink also significantly increased after EDTA solution was applied (p<0.05), but the increase for Zn was insignificant. EDTA treatment significantly increased the total uptake of Pb in the shoot, over that obtained with the control treatment (p<0.001), but it did not significantly increase the total uptake of Cd and Zn. The concentrations of Zn and Pb in the shoots of rainbow pink are significantly correlated with those in the soil solution, but no relationship exists with concentrations in vetiver grass. The toxicity of highly contaminating metals did not affect the growth of vetiver grass, which was found to grow very well in this study. Results of this study indicate that rainbow pink can be considered to be a potential phytoextraction plant for removing Cd or Zn from metal-contaminated soils, and that vetiver grass can be regarded as a potential phytostabilization plant that can be grown in a site contaminated with multiple heavy metals. [Copyright &y& Elsevier]

Freshwater sediments and water samples were quarterly collected at different sampling stations from August 1996 to April 1998 in the Fei-Tsui reservoir watershed (FTRW) of northern Taiwan. The sediment and soil samples were digested using mixture of inorganic acids to analyze the total concentration of ten metals. The baseline concentrations of ten metals in the sediments of FTRW were calculated from the geometric mean (GM) values and the geometric standard deviation (GSD). The baseline concentrations of 10 metals in the 239 sediments of this watershed are listed as followings (mg/kg, only % for Fe): As 1.80–51.5, Cd 0.04–7.54, Cr 5.25–273, Cu 2.65–91.7, Hg 0.03–0.26, Mn 18.6–2310, Ni 3.95–167, Pb 1.10–75.4, Zn 6.46–327, and Fe 0.47–9.63%. However, the GMs of 10 metal concentrations in the sediments were lower than the regulated threshold concentrations in Taiwan rural soils. Highly correlations among different metals in the sediments of FTRW indicate that very similar sediments of formation process control the metal content associated with the parent materials. Inadequate land use results in As, Cr, Mn, and Ni accumulated in the sediment to show potentially contamination risk in the study area associated with accelerated erosion and runoff. [ABSTRACT FROM AUTHOR]

States that four subalpine loamy Spodosols with illuvial clay in the spodic horizons in Taiwan, were selected to determine their characteristics, micromorphology and genesis. Methodology used to conduct study in this area; Description of the Spodosols; Details on their physical and chemical characteristics; Findings of morphological and micromorphological studies conducted; Discussion on results.

[Display omitted] The distribution of rare earth elements (REEs) in soils is affected by climate, which is one of the main factors controlling soil formation. However, variations in the geochemical behavior of soil REEs with pedoclimatic changes have rarely been investigated. This study determined the mobilization/retention and fractionation of REEs in nine soil profiles derived from sandy shale along an elevation gradient from 49 m to 2394 m above sea level in the Central Mountain Range of Taiwan. The experimental results indicated a gradually decreased ΣREEs trend with increasing elevation/rainfall. Clay content significantly (p < 0.05) correlated with REEs, which accumulated in argillic horizons. Moreover, a decreasing Gd N /Yb N ratio with increasing secondary minerals (i.e., clay and pedogenic Fe and Al oxides) implied their preferential sequestration tendency for heavy REEs over light REEs. This preferential association coupled with intensifying illuviation along the climatic gradient, resulted in increasing La N /Sm N and decreasing Gd N /Yb N ratios with increasing weathering degree and elevation (p < 0.01). Our results demonstrate that in the studied humid tropical region, increasing moisture availability caused by higher rainfall and lower air temperatures with rising elevation has led to stronger illuviation and more advanced soil development, which is reflected in REE fractionation and can be quantified by the ratios Gd N /Yb N and La N /Sm N. [ABSTRACT FROM AUTHOR]

Abstract: The fundamental purposes of teaching are to impart knowledge, insight, and inspiration. Around the world, university teaching principles are changing as students also gain knowledge and inspiration in ways other than in the class room. Likewise, the soil science discipline is evolving as there is a new set of tools and techniques available by which we investigate soils, and the foci are shifting toward other disciplines and changing research questions. In many universities, the teaching of undergraduate soil science increasingly takes place to non-soil science majors. All these forces require some thinking about how we teach the subject and here we present some of our experiences and ideas of teaching soil science in different parts of the world. Some 15 examples are presented from Australia, Canada, France, Germany, New Zealand, Russia, Taiwan, The Netherlands, and the USA. As the research is widening so is our teaching. The examples are diverse and, despite cultural and personal differences, they show several trends. The cases represent vibrant and creative ways to teach soils, and the initial focus is to create a sense of wonder about the soil and its utilitarian and scientific value. [Copyright &y& Elsevier]

Soil organic carbon (SOC) stocks are controlled by factors with varying degrees of importance at different spatial scales. In this study, soil data were collected from recently sampled pedons and previous studies on volcanic origin soils in Yangmingshan (YMS) National Park in northern Taiwan. This study evaluated the effect of soil order, vegetation type and elevation on the SOC stocks of humid subtropical volcanic ash soils. Analysis results indicate that SOC stock (mean±standard deviation) was 15.6±4.5kgm−2 m−1 (n=40) for Andisols and 17.3±7.3kgm−2 m−1 (n=20) for Inceptisols with andic soil properties. Meanwhile, SOC stocks under silver grass (17.4±5.5kgm−2 m−1, n=20) and bamboo (17.9±2.5kgm−2 m−1, n=8) were significantly higher than those under secondary forests (14.9±6.0kgm−2 m−1, n=32). Additionally, statistically significant linear regressions were found between the mean SOC stock and the mean of elevation classes. Climate, vegetation types and soil mineralogy vary along elevation gradients in the complex terrain. Our results demonstrated that elevation is a simple and effective predictor of SOC stock. [ABSTRACT FROM AUTHOR]

Chelate-induced phytoextraction is an innovative technique for cleaning metal- contaminated soil. The present study evaluates the degree of metal mobilization in soil and enhancement of phytoextraction of cadmium (Cd), lead (Pb), and zinc (Zn) by Sesbania sesban (L.) Merr. from artificially contaminated soil by application of ethylenediaminetetraacetic acid (EDTA). After 30 days of plant growth, the pots were divided into three sets (0.0, 2.5, and 5.0 mmol EDTA per kg soil). Experimental results indicated that levels of diethylenetriaminepentaacetic acid (DTPA)-extractable metals and metals in the leachate decreased as the EDTA dose increased. Plant growth parameters and total chlorophyll contents in the plants with EDTA applied were less than those of control. However, EDTA application significantly reduced metal accumulation in root and increased metal accumulation in the shoot of plants; similar results were obtained for the bioconcentration factor and translocation factor. The application of 5 mmol EDTA kg-1 to metal-spiked soil may be an efficient alternative for the chemically enhanced phytoextraction by S. sesban. [ABSTRACT FROM AUTHOR]

A site in central Taiwan with an area of 1.3 ha and contaminated with Cr, Cu, Ni, and Zn was selected to examine the feasibility of phytoextraction. Based on the results of a pre-experiment at this site, a total of approximately 20,000 plants of 12 species were selected from plants of 33 tested species to be used in a large-area phytoextraction experiment at this site. A comparison with the initial metal concentration of 12 plant species before planting demonstrated that most species accumulated significant amounts of Cr, Cu, Ni, and Zn in their shoots after growing in this contaminated site for 31 d. Among the 12 plant species, the following accumulated higher concentrations of metals in their shoots; Garden canna and Garden verbena (45-60 mg Cr kg-1), Chinese ixora and Kalanchoe (30 mg Cu kg-1), Rainbow pink and Sunflower (30 mg Ni kg-1), French marigold and Sunflower (300-470 mg Zn kg-1). The roots of the plants of most of the 12 plant species can accumulate higher concentrations of metals than the shoots and extending the growth period promotes accumulation in the shoots. Large-area experiments demonstrated that phytoextraction is a feasible method to enable metal-contaminated soil in central Taiwan to be reused. [ABSTRACT FROM AUTHOR]

Many studies have been conducted on phytoextraction; however, non-native hyperaccumulator species are not suitable for the natural environment of Taiwan in many cases. Drawing upon previous results, the growth and heavy metal accumulation in artificially cadmium-contaminated soils were compared for five local garden flower species. The treatments included a control (CK), 9.73 ± 0.05 mg kg-1 (Cd-10), and 17.6 ± 0.8 mg kg-1 (Cd-20). All plants were harvested at 35 days after transplanting and analyzed for Cd content. Cd accumulation in the shoot of French marigold (Tagetes patula L.) and Impatiens (Impatiens walleriana Hook. f.) grown in Cd-20 treatment were 66.3 ± 6.5 and 100 ± 11 mg kg-l, which equated to a removal of 0.80 ± 0.11 and 0.60 ± 0.37 mg Cd plant-1, respectively. The maximum Cd accumulation of Impatiens reached the threshold value (100 mg kg-l) characteristic of a Cd hyperaccumulator and its bioconcentration factor (BCF) and translocation factor (TF) were greater than one. Impatiens therefore has the potential to hyperaccumulate Cd from Cd-contaminated soils. With the exception of Garden verbena, significant relationships were found between Cd concentrations in soil extracted by 0.05 M EDTA, 0.005 M DTPA, and 0.01 M CaCl2 and the concentration of Cd in the shoots of the tested garden flowers. [ABSTRACT FROM AUTHOR]

Most of the metals-contaminated and fallow lands in Taiwan are a result of irrigation with illegal effluent of factories. Phytoextraction methods can be applied to reach the target of fallow-lands reuse and earn more incomes for farmers. In many studies, Indian mustards (Brassica juncea) were planted in the metal-contaminated soils to study their suitability in phytoextraction. However, the total removal of metals by plants was quite different between accessions. In this pot study, three accessions of B. juncea (cv. 182921, cv. 211000, and cv. 426308) were planted in artificially Cd- or Pb-contaminated soils to investigate the differences between them. EDTA was applied to study its effect in increasing the bioavailability of Cd and Pb and their uptake by these Indian mustards. Experimental result showed that three accessions of Indian mustard can accumulate a high concentration of Cd and Pb when growing in the artificially Cd- and Pb-contaminated soils. Their shoot Cd or Pb concentrations were significantly enhanced, resulting from the application of EDTA. Among the three accessions, B. juncea cv. 211000 accumulated the highest concentrations of Cd and Pb in their shoots compared with B. juncea cv. 182921 and cv. 426308, but its total removal was the lowest due to its lower biomass. [ABSTRACT FROM AUTHOR]

Abstract: To understand whether soils on the same geomorphic surface have similar properties, this study examines the morphology of soils developed on the 30-kyr-old Taoyuan Terrace, Northwestern Taiwan. Relationships among soil morphology, variations in the groundwater table, and soil forming processes were established based on field investigations and previously published datasets. The soil series in the study area can be grouped into seven types, including three homogeneous groups, two mottled groups, one gley group, and one reworked group. Fifteen hand-core samples collected in the field and borehole data were used to understand spatial variations in soil morphology. The results indicate that soil morphology on the southern Taoyuan Terrace changes systematically from the fore-edge to the back-edge: from red/orange soils to yellow soils, then to mottled soils, and finally to gley soils. The borehole data indicate that the groundwater table is generally parallel to the ground surface but drops significantly near the terrace fore-edge. This pattern matches with the observed soil toposequence, indicating that the pedogenic processes in the study area are mainly controlled by groundwater distribution determined by topography. Although soils on the terrace fore-edge have developed under the well-drained conditions that favor lateritization, at least two distinct soil types (i.e., red and orange) can be observed there, reflecting different geomorphological settings in a paleo-fluvial landscape. This work suggests that geomorphological and hydrological conditions should be examined carefully before using soil morphology for correlating geomorphic surfaces. [Copyright &y& Elsevier]

The availability of metal in contaminated soil can be reduced by the addition of soil amendments. The objectives of this study are to study the effects of applying different soil amendments on the concentration of Cd and Pb in soil solution, DTPA or EDTA extractable Cd and Pb, and the uptake of Cd and Pb by wheat (Triticum vulgare) when growing in long-term Cd and Pb-contaminated soils, more than 20 years. The soil amendments, including check, compost, zinc oxide, calcium carbonate, calcium carbonate mixed with zinc oxide, and calcium carbonate mixed with compost, were conducted in a four replicates pot cultural study. The amended soils were incubated for six months under 60% of water holding capacity. Following incubation, wheat was grown for four months in greenhouse. Analyses of Cd concentration demonstrated a significant decrease in soil solution concentration and DTPA or EDTA extractable in soils amended with calcium carbonate or calcium carbonate mixed with ZnO (or compost) (p<0.01). These amendments can significantly reduce the Cd concentration in the grain, leaf and stem, or reduce the total Cd uptake in all parts of wheat species grown in highly contaminated soil amended with calcium carbonate or calcium carbonate mixed with ZnO (or compost) (p<0.01). The concentration of Cd in soil solution and extracted with DTPA or EDTA can predict the Cd concentration in wheat, especially for soil solution. [Copyright &y& Elsevier]

Placic (Bsm) horizons are commonly found in different types of soils worldwide, but are very rare in Ultisols. The formation of Bsm horizon and podzolization are different processes in pedogenesis. This study collected five podzolic Ultisols containing Bsm horizons from the subalpine forests in Taiwan to illustrate the morphological characteristics and genesis of the Bsm horizons in these soils with both clay illuviation and podzolization. The distinctive Bsm horizons were 3 to 10 mm thick and had abrupt and wavy boundaries with overlying albic (E) and underlying argillic (Bt) horizons. All Bsm horizons contained over 35% of clay fraction which significantly increased from E horizon to B horizons in the pedons. The Bsm horizons showed much higher bulk density than adjacent horizons above or below them, elucidating that such iron pans were relatively impermeable to water and plant roots. The maximum contents of pedogenic Fe occurred in the Bsm horizons mainly cemented by poorly crystalline Fe oxides associated with high amounts of organic matter and epiaquic conditions. Pedogenic Al appeared to be accumulated in the Bt horizons where spodic materials were identified according to the oxalate-extractable amount of Fe and Al. The polygenetic processes of these podzolic Ultisols with Bsm horizons were proposed as three stages. Firstly, clay illuviation predominantly occurred to form Bt horizon in the interglacial periods during the mid to late Pleistocene. Then, podzolization gradually became a major process to accumulate spodic materials in the Bt horizon because of the coniferous forest formation under the cool and humid climates close to the late Pleistocene; however, water was perched at the soil surface due to poor drainage and abrupt textural change between E and Bt horizons after the Holocene. Eventually, the reduced iron from E horizon was gradually re-oxidized and precipitated on the top of Bt horizon where exhibited oxidizing condition to form Bsm horizon until today. Because of the occurrence of Bsm horizon in these Ultisols, a new subgroup Placic Epiaquults, was therefore proposed to the keys to Soil Taxonomy. • The pedons confirmed the existence of placic horizons in spodic Ultisols. • Clays and spodic materials were accumulated prior to the formation of Bsm horizon. • These polygenetic processes were corresponding to the paleoclimate changes. • Placic Epiaquults was proposed as a new subgroup in the keys to Soil Taxonomy. [ABSTRACT FROM AUTHOR]

• This is the first study to predict the criteria of Spodosols using pXRF and Vis-NIR. • Principal component analysis extracted variances of spodic materials from spectra. • Soil horizons separated by k-means clustering matched field-assigned horizons. Proximal soil sensing is a promising tool to quantify soil properties through spectral data and machine learning algorithms for application in pedological investigations. However, the relationship between pedological characteristics and sensor signals is difficult to be elucidated with machine learning models. This study aimed to establish direct linkages between pedological features and data from proximal sensors, namely portable X-ray fluorescence spectrometry (pXRF) and visible and near-infrared spectroscopy (Vis-NIR). Ten podzolic soil profiles, including seven Spodosols, two Ultisols, and one Inceptisol, were described and sampled from Central Taiwan. Principal component analysis (PCA) and k-means clustering method revealed that the major variances of the pXRF were affected by the amounts of spodic materials and organic carbon derived from plant debris. For Vis-NIR, a remarkable absorption of Fe-oxides was observed in the B horizons, and the major variations of Vis-NIR spectra extracted by PCA represented the influence of metal-complexed organic carbon and clay. The principal components (PC) of pXRF and Vis-NIR can be used to separate soil horizons, especially the E horizons were clearly separated as indicated by its high user's and producer's accuracies. However, the B and C horizons were poorly separated by the PCs and k-means clustering method. Moreover, the PCs can be used directly to predict the nanocrystalline Fe and Al and the optical density of the oxalate extract. Ten soil profiles were classified based on the predicted values, and nine out of ten soil profiles were in agreement with their classification using chemical extractions. The proposed pXRF and Vis-NIR approaches predicted the chemical criteria of diagnostic horizons and facilitated fast determination of Spodosols. [ABSTRACT FROM AUTHOR]

The ‘4 per mille Soils for Food Security and Climate’ was launched at the COP21 with an aspiration to increase global soil organic matter stocks by 4 per 1000 (or 0.4 %) per year as a compensation for the global emissions of greenhouse gases by anthropogenic sources. This paper surveyed the soil organic carbon (SOC) stock estimates and sequestration potentials from 20 regions in the world (New Zealand, Chile, South Africa, Australia, Tanzania, Indonesia, Kenya, Nigeria, India, China Taiwan, South Korea, China Mainland, United States of America, France, Canada, Belgium, England & Wales, Ireland, Scotland, and Russia). We asked whether the 4 per mille initiative is feasible for the region. The outcomes highlight region specific efforts and scopes for soil carbon sequestration. Reported soil C sequestration rates globally show that under best management practices, 4 per mille or even higher sequestration rates can be accomplished. High C sequestration rates (up to 10 per mille) can be achieved for soils with low initial SOC stock (topsoil less than 30 t C ha − 1 ), and at the first twenty years after implementation of best management practices. In addition, areas which have reached equilibrium will not be able to further increase their sequestration. We found that most studies on SOC sequestration only consider topsoil (up to 0.3 m depth), as it is considered to be most affected by management techniques. The 4 per mille number was based on a blanket calculation of the whole global soil profile C stock, however the potential to increase SOC is mostly on managed agricultural lands. If we consider 4 per mille in the top 1m of global agricultural soils, SOC sequestration is between 2-3 Gt C year − 1 , which effectively offset 20–35% of global anthropogenic greenhouse gas emissions. As a strategy for climate change mitigation, soil carbon sequestration buys time over the next ten to twenty years while other effective sequestration and low carbon technologies become viable. The challenge for cropping farmers is to find disruptive technologies that will further improve soil condition and deliver increased soil carbon. Progress in 4 per mille requires collaboration and communication between scientists, farmers, policy makers, and marketeers. [ABSTRACT FROM AUTHOR]

Understanding the role of biodiversity (B) in maintaining ecosystem function (EF) is a foundational scientific goal with applications for resource management and conservation. Two main hypotheses have emerged that address B-EF relationships: niche complementarity (NC) and the mass-ratio (MR) effect. We tested the relative importance of these hypotheses in a subtropical old-growth forest on the island nation of Taiwan for two EFs: aboveground biomass (ABG) and coarse woody productivity (CWP). Functional dispersion (FDis) of eight plant functional traits was used to evaluate complementarity of resource use. Under the NC hypothesis, EF will be positively correlated with FDis. Under the MR hypothesis, EF will be negatively correlated with FDis and will be significantly influenced by community-weighted mean (CWM) trait values. We used path analysis to assess how these two processes (NC and MR) directly influence EF and may contribute indirectly to EF via their influence on canopy packing (stem density). Our results indicate that decreasing functional diversity and a significant influence of CWM traits were linked to increasing AGB for all eight traits in this forest supporting the MR hypothesis. Interestingly, CWP was primarily influenced by NC and MR indirectly via their influence on canopy packing. Maximum height explained more of the variation in both AGB and CWP than any of the other plant functional traits. Together, our results suggest that multiple mechanisms operate simultaneously to influence EF, and understanding their relative importance will help to elucidate the role of biodiversity in maintaining ecosystem function. [ABSTRACT FROM AUTHOR]

A fundamental goal in ecology is to link variation in species function to performance, but functional trait-performance investigations have had mixed success. This indicates that less commonly measured functional traits may more clearly elucidate trait-performance relationships. Despite the potential importance of leaf vein traits, which are expected to be related to resource delivery rates and photosynthetic capacity, there are few studies, which examine associations between these traits and demographic performance in communities. Here, we examined the associations between species traits including leaf venation traits and demographic rates (Relative Growth Rate, RGR and mortality) as well as the spatial distributions of traits along soil environment for 54 co-occurring species in a subtropical forest. Size-related changes in demographic rates were estimated using a hierarchical Bayesian approach. Next, Kendall's rank correlations were quantified between traits and estimated demographic rates at a given size and between traits and species-average soil environment. Species with denser venation, smaller areoles, less succulent, or thinner leaves showed higher RGR for a wide range of size classes. Species with leaves of denser veins, larger area, cheaper construction costs or thinner, or low-density wood were associated with high mortality rates only in small size classes. Lastly, contrary to our expectations, acquisitive traits were not related to resource-rich edaphic conditions. This study shows that leaf vein traits are weakly, but significantly related to tree demographic performance together with other species traits. Because leaf traits associated with an acquisitive strategy such as denser venation, less succulence, and thinner leaves showed higher growth rate, but similar leaf traits were not associated with mortality, different pathways may shape species growth and survival. This study suggests that we are still not measuring some of key traits related to resource-use strategies, which dictate the demography and distributions of species. [ABSTRACT FROM AUTHOR]

Five different soil types, including Entisol, Inceptisol, Alfisol, Ultisol and Oxisol, are distributed across west-central Taiwan. These soils cover the surfaces of three geological terrains, namely, the Pleistocene anticline, the Holocene coastal plain, and the modern alluvial fan. These soils developed from the similar parent materials, facilitating the analysis of soil diversity and the processes of pedogenesis. The soil chronosequence of Entisol → Inceptisol (Endoaquept) → reddish Inceptisol (Dystrudept) → Ultisol → Oxisol with increasing age is suggested for the progressive pathway of soil development. The degree of pedogenesis was quantified using a weighted profile development index (WPDI), which indicates that the soils from the tropics develop faster than those in temperate and/or Mediterranean climates, but was not as fast as those documented in the published literature. Moreover, the distribution of soils during pedogenesis conformed to the order of landform formation. Soil genesis and the way in which the different soils evolve illustrate the paleo-environments of the fluvial system in the area. [ABSTRACT FROM AUTHOR]

Spatially explicit consideration of species distribution can significantly add to our understanding of species coexistence. In this paper, we evaluated the relative importance of habitat heterogeneity and other clustering processes (e.g., dispersal limitation, collectively called the non-habitat clustering process) in explaining the spatial distribution patterns of 341 tree species in three stem-mapped 25-50 ha plots of tropical, subtropical, and temperate forests. Their relative importance was estimated by a method that can take one mechanism into account when estimating the effects of the other mechanism and vice versa. Our results demonstrated that habitat heterogeneity was less important in explaining the observed species patterns than other clustering processes in plots with flat topography but was more important in one of the three plots that had a complex topography. Meanwhile, both types of clustering mechanisms (habitat or non-habitat) were pervasive among species at the 50-ha scale across the studied plots. Our analyses also revealed considerable variation among species in the relative importance of the two types of mechanism within each plot and showed that this species-level variation can be partially explained by differences in dispersal mode and growth form of species in a highly heterogeneous environment. Our findings provide new perspectives on the formation of species clustering. One important finding is that a significant species-habitat association does not necessarily mean that the habitat heterogeneity has a decisive influence on species distribution. The second insight is that the large species-level variation in the relative importance of the two types of clustering mechanisms should not be ignored. Non-habitat clustering processes can play an important role on species distribution. [ABSTRACT FROM AUTHOR]

Individual performance is a function of an individual's traits and its environment. This function, known as an environmental filter, varies in space and affects community composition. However, filters are poorly characterized because dispersal patterns can obscure environmental effects, and few studies utilize longitudinal data linking individual performance to environment., We model the effects of environmental filters on demographic rates of nearly all tree species (99) in a 25-ha subtropical rain forest plot. We develop a hierarchical Bayesian model of environmental filtering, drawing inspiration from classic studies of intraspecific natural selection. We characterize the specific environmental gradients and trait axes most important in filtering of demographic rates across species., We found that stronger filtering along a given trait axis corresponded to less spatial variation in the value of favoured traits., Environmental gradients associated with filtering were different for growth versus survivorship., Species maximum height was under the strongest filtering for growth, with shorter species favoured on convex ridges. Shorter stature species may be favoured on ridges because trees on ridges experience higher wind damage and lower soil moisture., Wood density filtering had the strongest effects on survival. Steep slopes and high available P in the soil favoured species with low-density wood. Such sites may be favourable for fast-growing species that exploit resource-rich environments., Synthesis: We characterized trait-mediated environmental filters that may underlie spatial niche differentiation and life-history trade-offs, which can promote species coexistence. Filtering along trait axes with the strongest effects on local community composition, that is, traits with the strongest filtering, may necessarily have a weaker potential to promote species coexistence across the plot. The weak spatial variation in filters with strong effects on demography may result from long-term processes affecting the species pool that favour habitat generalist strategies. [ABSTRACT FROM AUTHOR]

Abstract: The Tadu tableland is located at the deformation front of the Western Foothills in central Taiwan. The surface of the tableland is covered by reddish soils and gravels, and is folded symmetrically with gently dipping strata running toward both wings. Previous geomorphic studies suggested a fluvial terrace landform developed on the surfaces of the tableland. However, other suggestions have been proposed in recent years. This study attempts to solve the argument by examining the pedogenesis of surface deposits. Five soil pedons were sampled to the depths of C horizons in the surface deposits of the tableland. Strong migration of illuvial clay was indicated by the accumulation of significant clay coatings in the sub-surface soils. These soils were classified as Paleudult and Kandiudult of Ultisols according to Soil Taxonomy. In addition, their morphological characteristics were further quantified in terms of soil development by the horizon index and weighted profile development index (WPDI). The WPDI values of 0.64–0.73 for the soils of the Tadu tableland agree with those of Ultisols developed on the Pakua tableland. Both qualification and quantification assessments indicate all soils of the Tadu tableland are equivalent in terms of degree of pedogenesis. As a result, all the geomorphic surfaces on the tableland probably developed at the same time, which rules out the interpretation of fluvial terraces developing on the tableland. The pedogenic evidence conditionally supports the recently proposed kinematic model for the development of the Tadu tableland. [Copyright &y& Elsevier]

Abstract: Soil chronosequences developed on elevated marine terraces are ideal for studying changes in soil-forming processes with time. The coastal range of eastern Taiwan is a product of active arc–continent collision. Vertisols, Mollisols and Entisols are generally found on the different levels of marine terraces herein, but no detailed investigations of soil chronosequence have been conducted by integrating field morphology, physio-chemical characterization, micromorphology and mass-balance interpretations. Five soil pedons were selected on the three marine terraces including Tt-1 and Tt-2 pedons (Typic Hapluderts) on the first higher level with the oldest soil age (9–10 ka), Tt-3 (Vertic Hapludolls) and Tt-4 pedons (Typic Hapludolls) on the second intermediate level (5–6 ka), and Tt-5 pedon (Typic Udipsamments) on the third lower level with the youngest soil age (≤3.5 ka). The morphological characteristics showed that strongly developed angular blocky structures, pressure faces and slickensides are more common in higher terrace soils than in lower terrace soils. In this study, depth to C horizon, solum thickness, and thickness of the clay-enriched zone increase with relative terrace age. Although only one to two profiles per terrace were characterized, the following soil analytical characterizations increase with time: the degree of sand grains weathering, pH (H2O), organic carbon, CEC, contents of Fed, Feo and Mnd. Based on X-ray diffraction analysis of the clay-size fraction, soils on all terraces have a mixed mineralogy. Mica, smectite, and kaolinite have slightly increased with increasing terrace age. Furthermore, the dominant processes identified with mass-balance analysis include loss of bases (Ca and Mg), iron, and clay with time. The soil properties, including analytical and mineralogical characterizations, which do not have notable changes with time are primarily due to relatively young soil age (<10 ka). [Copyright &y& Elsevier]

Abstract: This study examines the relationships between topography and spatial variations in groundwater and soil morphology within the multi-step Taoyuan–Hukou Tableland in northwest Taiwan. Several different geomorphological and pedological approaches were jointly undertaken, including analyses of a digital elevation model (DEM), a reclassified soil map, field survey results, engineering borehole data, and a hydrological simulation. Five major geomorphic surfaces were identified based on terrace scarps observed in the DEM; minor surfaces separated by small fluvial scarps or tectonic scarps were also mapped. The simplified soil map and field study of soil morphology reveal a number of soil-distribution patterns associated with specific topographic settings. Soil morphology changes from homogeneous red soils in the fore-edge of surfaces to mottled soils and finally to gley soils in back-edge regions. Such a pattern is more pronounced in the proximal part of a surface, while toward the distal zone the patterns tend to be obscured by increasing amounts of mottled and gley soils. The proportion of homogeneous soils increases with narrowing of the surface. For fan-shaped surfaces, soil types appear to be dominated by mottled soils except for at terrace edges, where homogeneous red soils occur. While homogeneous soils dominate tectonically elevated surfaces, a toposequence of homogeneous-mottled-gley soils occurs in the surrounded lowlands. Borehole data and hydrological models indicate that these soil-distribution patterns are strongly related to groundwater occurrence and fluvial processes, both of which are generally governed by topography. Despite the observed pedodiversity in this area, the common feature of these toposequences, i.e., the distribution of homogeneous red soils along the surface fore-edge, may serve as a basis for establishing a reliable soil chronosequence for the area. [Copyright &y& Elsevier]

Abstract: The southern part of the Pakua tableland in Taiwan comprises a series of wide, unpaired river terraces that have as many as six altitude levels, from PK-1 (highest) to PK-6 (lowest). The terrace surfaces are covered with lateritic soils. This study described, sampled and analyzed the soils from each terrace. Soil taxonomies are Oxisol, Ultisol and Inceptisol. Soil morphological characteristics were quantified as a profile development index (PDI) to determine the degree of soil development. The chemical analyses included cation exchange capacity (CEC) and selected extraction of Fe in soils. Based on the degree of soil development, surface deposits on terrace flights form the post-incisive soil chronosequence, supporting the hypothesis of terrace formation by fluvial processes. Soil ages were estimated based on iron crystallinity (Fed–Feo)/Fet. Analytical results indicate that river terraces in the Pakua tableland are aged 40–400 ka. The long-term uplift rate of the tableland can be estimated using terrace ages and folding geometry. The variation of uplift rates demonstrates that the landscape underwent increased shortening of frontal thrusting by the Changhua Fault running beneath the tableland. [Copyright &y& Elsevier]

Abstract: The natural speciation of Mn (0.19 g/kg), Ni (46 mg/kg), and Zn (42 mg/kg) in the argillic horizon (120 cm depth, pH = 5.6) of an Ultisol from a paddy soil in northern Taiwan was investigated by advanced X-ray synchrotron techniques. Microchemical associations were imaged by synchrotron-based X-ray microfluorescence, host minerals were identified by standard and micrometer-resolved X-ray diffraction, and the local coordination environment of Mn, Ni, and Zn was probed using extended X-ray absorption fine structure (EXAFS) spectroscopy on a powdered sample and a soil thin section, and polarized EXAFS spectroscopy on a highly textured self-supporting clay film from the &#60;2 μm fraction of the soil. Manganese was concentrated in Fe-Mn soft mottles (44.4 g/kg) as turbostratic hexagonal birnessite and lithiophorite having Mn3+/Mn4+ atomic ratios of ∼20% and 50%, respectively. Quantitative analysis of high-order scattering paths of the EXAFS spectrum for natural and synthetic lithiophorite revealed that Mn3+ and Mn4+ are ordered in the layer. A structural model is proposed, in which Mn4+ and Mn3+ are ordered similarly to Al and Li in the layer, with Mn3+ cations being surrounded by six Mn4+, and Mn4+ cations by three Mn3+ and three Mn4+. Similar cation ordering in the manganese and aluminum layers likely provides a more homogeneous local balance of the excess and deficit of charges in each layer and increases the stability of lithiophorite. Ni (r = 0.70 Å) substitutes for Mn (r(Mn4+) = 0.54 Å, r(Mn3+) = 0.65 Å) in the manganese layer in the natural lithiophorite. In contrast, Zn (r = 0.74 Å) fills vacant sites in the gibbsitic layer of natural lithiophorite, in a similar manner as lithium (r = 0.74 Å) in synthetic lithiophorite. The partitioning of Ni and Zn between the two layers is a result of the general preference of Ni, whose size is intermediate between those of Mn3+ and Li+, for slightly smaller sites. In contrast with nickel, which is detected only where there is lithiophorite, the Zn-lithiophorite association found in Fe-Mn mottles is not representative of the bulk soil. The combined use of X-ray diffraction, and powder and polarized EXAFS spectroscopy revealed that Zn is predominantly bound to hydroxy-Al interlayers sandwiched between 2:1 vermiculite layers in the fine soil matrix. The incorporation of Zn in the gibbsitic layer of both lithiophorite and vermiculite helps increase the stability of these minerals by providing positive charge to balance the negative charge from the 2:1 phyllosilicate layer and the layer of lithiophorite. This binding environment for zinc is probably the main mechanism by which zinc is sequestered in acidic to near-neutral aluminum-rich clayey soils. [Copyright &y& Elsevier]