Solution Electrical Conductivity Research Articles

Saturação do complexo de troca de solos oxídicos com sódio

Propôs-se, neste trabalho, avaliar a influência de características físicas, químicas e mineralógicas de três solos oxídicos no potencial de sua sodificação. Nesta avaliação foram utilizadas amostras coletadas no horizonte B, de um Latossolo Vermelho-Amarelo, Latossolo Vermelho e um Argissolo Vermelho, que apresentavam, respectivamente, presença marcante dos minerais caulinita, hematita e gibbsita. As amostras foram caracterizadas em termos físicos, químicos e mineralógicos e, após seu acondicionamento em colunas de solo, submetidas à percolação de soluções com condutividade elétrica (CE) de 8,0 dS m-1 e relação de adsorção do sódio (RAS) de 0, 10, 20, 30, 40 e 50 (mmol c L-1)0,5, em três repetições. A porcentagem de sódio trocável (PST) e a relação de sódio trocável (RST) foram obtidas por cálculo a partir dos valores de concentração trocável de sódio nos solos. O aumento na RAS da solução de percolação proporcionou aumento nas RST e PST em todos os solos e foi influenciado pela mineralogia, grau de intemperismo e conteúdo de argila. Os solos analisados podem receber águas com RAS e CE altas sem sofrer sodificação expressiva.

EFFECT OF ELECTRICAL CONDUCTIVITY OF THE NUTRIENT SOLUTION ON THE GROWTH AND YIELD OF THREE NATIVE TOMATO GENOTYPES (LYCOPERSICON ESCULENTUM VAR. CERASIFORME)

ISHS International Symposium on Growing Media and Soilless Cultivation EFFECT OF ELECTRICAL CONDUCTIVITY OF THE NUTRIENT SOLUTION ON THE GROWTH AND YIELD OF THREE NATIVE TOMATO GENOTYPES (LYCOPERSICON ESCULENTUM VAR. CERASIFORME)

The Effect of EC Levels of Nutrient Solution on the Growth, Yield, and Quality of Tomatoes (Solanum Lycopersicum) under the Hydroponic System

The objective of this research was to investigate the effect of EC (electric conductivity) levels of nutrient solution on the growth and yield of tomatoes under the hydroponic system. This research was conducted in a plastic house on the experimental farm of Lampung University, Lampung in Indonesia from April to July 2009. The EC treatments to nutrient solutions were S1 (1 dSm-1), S2 (2 dSm-1), S3 (3 dSm-1), S4 (4 dSm-1), and S5 (5 dSm-1) arranged in a completely randomized design with four replications. The results showed that the highest yield was under S3 (120.8 g/plant), followed by S2 (96.6 g/plant), S1 (89.7 g/plant), S4 (88.4 g/plant), and S5 (75.5 g/plant). The yields of tomato responded to EC levels of nutrient solution in the two ranges of lower and higher EC than 3 dSm-1. The yield increased as EC of nutrient solution increased from 0 to 3 dSm-1 probably, due to increase of nutrients. On the other hand, the yield decreased as the EC of nutrient solution increased from 3 to 5 dSm-1 probably, due to increase of water stress. So, it can be concluded that the salinity threshold of the tomatoes was 3 dSm-1. On the other hand, the highest SSC (soluble solid content) was recorded under S5 (7.34 brix), followed by S4 (6.93 brix), S3 (6.44 brix), S2 (6.26 brix), and S1 (6.11 brix). It means that the S5 treatment was the best quality. Among the range of treatments, treatment S3 (3 dSm-1) gave the highest yield, but lower SSC than S4 (4 dmS-1) and S5 (5 dSm-1).

Forest fire effects on soil chemical and physicochemical properties, infiltration, runoff, and erosion in a semiarid Mediterranean region

Forest fires are a major environmental concern, especially in the semiarid Mediterranean regions, where the long dry and hot summers and mild winters favor outbreaks of wildfires. The objective of this work was to study the effects of different fire treatments on physical, chemical, and physicochemical properties of Pale rendzina, and their impact on infiltration rate (IR), runoff and soil loss under consecutive rainstorms. After a wildfire in a forest located in northern Israel, soil samples were taken from an area that was directly exposed to fire (direct fire treatment) and from adjacent unburned (unburned soil treatment). Part of the unburned soil was heated in a muffle at 300°C (heated soil treatment). Runoff, soil loss and IR values were measured for the various samples using a laboratory rainfall simulator, and aggregate stability was determined using slaking and dispersion values. The organic matter, clay, and sand content, and cation exchange capacity were significantly lower in the heated soil than in the unburned soil. The CaCO3 content in the heated soil was significantly higher than in the unburned and direct fire soils. In general, the IR values were highest, intermediate, and lowest and the runoff and soil loss amounts were lowest, intermediate, and highest in the heated, direct fire, and unburned soils, respectively. However, these differences decreased with progression of the consecutive rainstorms. Heating the soil to 300°C enhanced soil-structure stability, most likely due to increased dehydration of 2:1 clay minerals and transformation of iron and aluminum oxides which acted as cementing agents. In addition, soil heating increased the electrical conductivity (EC) and decreased the sodium adsorption ratio in the heated soil solution in the first rainstorm. These processes limited clay dispersion and seal formation in the heated soil, leading to high IR values and low runoff and soil loss. In the second and third rainstorms, EC of the soil solution decreased, which in turn increased clay dispersion. This lessened the differences in the IR values and runoff and soil loss amounts between the fire treatments in these rainstorms compared to the first rainstorm.

Use of threshold electrolyte concentration analysis to determine salinity and sodicity limit of irrigation water

ABSTRACT This research studied threshold electrolyte concentration (TEC) of irrigation water and its effect on the infiltration rate of two contrasting soils from Pernambuco state, Brazil. The experiment was conducted in the Soil Chemistry and Salinity Laboratory of Federal Rural University of Pernambuco. Each soil was packed in five Buchner funnels, where one funnel from each soil was submitted to treatment with solution of electrical conductivity (EC) of 0.5, 1.0, 2.0, 4.0 or 8.0 dS m-1. For each funnel containing soil, an increasing ratio of NaCl to CaCl2 was applied in a treatment solution to achieve 10 increasing values of sodium adsorption ratio (SAR) from 0 to 100. These solutions were applied through a Mariotte bottle, with a constant hydraulic head of ~2 cm (pressure potential). After a liter of solution had drained, in the flux was collected for a known time interval, until steady state was reached. Darcy’s equation was used to calculate saturated hydraulic conductivity (Ksat) and a mathematical model used to calculate the TEC as a 20% reduction in Ksat. By increasing SAR similar behavior was noted between the two soils, whereby Ksat decreased, although the relativedecrease in Ksat was greater for SAR of 100 in the soil with higher clay content.

Assessing the temporal stability of spatial patterns of soil apparent electrical conductivity using geophysical methods

A b s t r a c t. Cocoa remains in the same field for decades, resulting in plantations dominated with aging trees growing on variable and depleted soils. We determined the spatio-temporal variability of key soil properties in a (5.81 ha) field from the International Cocoa Genebank, Trinidad using geophysical methods. Multi-year (2008-2009) measurements of apparent electrical conductivity at 0-0.75 m (shallow) and 0.75-1.5 m (deep) were conducted. Apparent electrical conductivity at deep and shallow gave the strongest linear correlation with clay-silt content (R = 0.67 and R = 0.78, respectively) and soil solution electrical conductivity (R = 0.76 and R = 0.60, respectively). Spearman rank correlation coefficients ranged between 0.89-0.97 and 0.810.95 for apparent electrical conductivity at deep and shallow, respectively, signifying a strong linear dependence between measurement days. Thus, in the humid tropics, cocoa fields with thick organic litter layer and relatively dense understory cover, experience minimal fluctuations in transient properties of soil water and temperature at the topsoil resulting in similarly stable apparent electrical conductivity at shallow and deep. Therefore, apparent electrical conductivity at shallow, which covers the depth where cocoa feeder roots concentrate, can be used as a fertility indicator and to develop soil zones for efficient application of inputs and management of cocoa fields. K e y w o r d s: apparent electrical conductivity, electromagnetic-induction, humid tropics, spatial patterns, temporal stability

Electrospray synthesis of monodisperse polymer particles in a broad (60 nm–2 μm) diameter range: guiding principles and formulation recipes

This study reports on a methodology to control the size of polymer particles generated by the electrospray (ES) drying route, with emphasis on the generation of biodegradable polymer nanoparticles that are well suited for biomedical applications. The ability to produce spherical poly(lactic-co-glycolic) acid (PLGA) particles with and without encapsulated active agent, with relative standard deviation not exceeding 15%, was demonstrated over a remarkably broad (60nm–2μm) diameter range. By judiciously choosing ES parameters and solution properties, we can control the monodispersity and the size of the obtained particles, tailoring it to a specific application. The main parameters affecting particle size include solution electrical conductivity, flow rate and initial polymer volume fraction. Quasi-monodispersity at both the micro- and the more challenging nano-scale was achieved by avoiding Coulomb fission in the spray droplets, via entanglement of the polymer chains within the droplets rather than by charge neutralization. Guiding principles in the formulation of the solutions to satisfy a multiplicity of constraints are provided along with an extensive database of “recipes”.

Postharvest water quality affects vase life of cut Dendranthema, Dianthus, Helianthus, and Zinnia

Water quality can have a significant impact on the vase life of cut flowers. The effects of vase solution pH and electrical conductivity (EC) on the vase life and postharvest characteristics of Dendranthema L. ‘Naru Lavender’, Dianthus L. ‘Burgundy Sangria’, Helianthus L. ‘Sunbright’, and Zinnia L. ‘Benary's Giant Scarlet’ were investigated. Vase life of Dendranthema increased to 14.6d in acidic solutions from 6.1d for distilled water. Solution uptake of cut Dendranthema was also greater in acidic solutions (94mL) compared to distilled water (76mL). There was no significant difference in vase life of Dendranthema when solution EC ranged from 0.50dSm−1 (21.7d) to 4.00dSm−1 (19.3d) of NaCl; however, all solutions with NaCl resulted in a longer vase life than distilled water. For Dianthus the use of buffers to alter pH reduced vase life from 24.4d for the non-buffered control to 19.9d for the citrate buffered solutions, but no effect of actual pH was noted. Additionally, increasing the EC from 0.00 to 4.00dSm−1 decreased vase life by 10d. Cut Zinnia stems were not influenced by solution pH, but as EC increased from 0.00 to 4.00dSm−1 vase life decreased from 10.6 to 6.8d. Helianthus vase life was not affected by EC, but decreasing pH increased vase life by 1.1d when stems were held in acidic solutions compared to basic solutions. The use of commercial holding solution reduced the negative effects of high EC on salt-sensitive Dendranthema, Dianthus, and Zinnia and increased solution uptake. For Dendranthema vase life was 24.6d when held in preservative at an EC of 2.50dSm−1, while it was reduced to 17.4d without preservative at the same EC. For Helianthus, solutions with preservative had a solution uptake 10mL greater than solutions without preservative. In general, stems with longer vase lives also had a high incidence of necrotic leaves and petals, petal wilt and bent neck. In conclusion, each species had unique reactions to the vase solution treatments, but the general effects were consistent: high solution pH or EC or the use of buffers either had no effect or reduced vase life and the use of floral preservatives increased vase life.

The Degradation of Organic Pollutants by Bubble Discharge in Water

Organic pollutants could be degraded by using bubble discharge in water with gas aeration in the discharge reactor and more plasma can be generated in the discharge process. When pulsed high voltage was applied between electrodes with gas aerated into the reactor, it showed that bubbles were broken, which meant that breakdown took place. It could also be observed that the removal rate of phenol increased with increasing discharge voltage or pulse frequency, and with reducing initial phenol concentration or solution electric conductivity. It could remove more amount of phenol by oxygen aeration. With increasing oxygen flow rate, the removal rate increased. There was little difference with air or nitrogen aeration for phenol removal. The solution temperature after discharge increased to a great extent. However, this part of energy consumption did not contribute to the reaction, which led to a reduction in the energy utilization efficiency.

Electrical conductivity and pH of the substrate solution in gerbera cultivars under fertigation

The quality and the profitability on floriculture are intimately linked to the adequate plant nutrition. In the present research we aimed to evaluate the electrical conductivity (EC) and pH of the substrate solution on four different gerbera cultivars subjected to fertigation, with two nutritive solutions. The experiment was carried out in a greenhouse, from May to July 2006, on the Universidade Estadual Paulista, Botucatu, São Paulo state, Brazil. The experiment was carried out under an experimental design of random blocks, in 4×2 factorial arrangement, with four Gerbera cultivars (Cherry, Golden Yellow, Salmon Rose and Orange) and two nutritive solution concentrations: 0.92 and 1.76 dS m-1 EC) during the vegetative stage, and 1.07 and 2.04 dS m-1 during the reproductive stage (S1 and S2, respectively). The nutrients were applied through fertigation, manually performed every day. The EC and pH values of the substrate solution were evaluated weekly, using the 'pourthru' method. Orange and Cherry cultivars had, respectively, the highest and the lowest electrical conductivity of the substrate solution, and Cherry was the most efficient on the nutrient uptake. The solution S2 showed a trend to accumulate salts in the substrate, but without visual symptoms of plant toxicity, leading to the lowest pH values. The 'pourthru' method was efficient when compared to the 1:2 method and can be adopted for substrate solution analysis in gerbera culture.

MELON PRODUCTION USING FOUR HYDROPONIC SYSTEMS

Melon plants (Cucumis melo L.) were grown using four hydroponic systems of which three used the closed circulating nutrient solution system by deep-flow technique (DFT) but with different designs of growth containers namely, the triangular, double-U and U-shaped PVC containers. The fourth used an open fertigation system with plants grown in polybags containing coconut fiber (coco peat) as the growth medium. Comparisons were made among the systems in terms of nutrient solution electrical conductivity (EC), growth, yield, fruit total soluble solids (TSS) and leaf nutrient composition. Irrigation was applied based on crop transpiration (ET). Electrical conductivity of nutrient solution in triangular containers tended to be higher than the other systems especially during reproductive growth. The EC of nutrients in the solution was lowest with the double-U shaped among the different types of containers. Melon fruit fresh weight was highest with the double-U shaped containers compared to the other systems. However, no significant difference of fresh fruit weight was observed between polybags and triangular containers On the other hand, fruit quality as measured by the TSS (Brix 16) was highest in the U-shaped system compared to the other systems. The N, P, K, Ca and Mg content of leaf tissue of plants in the U-shaped container was also the highest compared to the other systems. During vegetative growth, Leaf Area Index of plants grown in polybags was significantly higher than in the other systems. In conclusion, there is evidence that the superior performance of U and Double-U shaped system was due to better aeration and temperature control.

수처리용 다중 유전체 방벽 방전 플라즈마 반응기 개발

Abstract Dielectric discharges are an emerging technique in environmental pollutant degradation, which that are characterized by the production of hydroxyl radicals as the primary degradation species. For practical application of the plasma reactor, reactor that can handle large amounts of water are needed. Plasma research to date has focused on small-scale water treatment. This study was carried out basic study for scale-up of a single DBD (dielectric barrier discharge) plasma reactor. The degradation of N, N-Dimethyl-4-nitrosoaniline (RNO, indicator of the generation of OH radical) was used as a performance indicator of multi-plasma reactor. The experiments is divided into two parts: design parameters [effect of distance of single plasma module (1~14 cm), arrangement of ground electrode (single and multi), rector number (1~5) and power number (1~5)]; operation parameter [effect of applied voltage (60~220 V), air flow rate (1~5 L/min), electric conductivity of solution (1.4 µS/cm, deionized water)~18.8 mS/cm (addition of NaCl 10 g/L) and pH (5~9)]. Considering the electric stability of the plasma reactor, optimum spacing between the single plasma module was 2 cm. Multi discharge electrodes - single ground electrode array was selected. Combination of power 3-plasma module 5 was the optimal combination for maximum RNO degradation. The optimum 1st voltage and air flow rate for RNO degradation were 180 V and 4 L/min, respectively. The pH and conductivity of the solution was not influencing the RNO degradation. Key words: Dielectric barrier discharge, Reactor module, Multi plasma, Design parameter, Water treatment

Concentration of trisodium citrate by electrodialysis

In this work, the experimental procedure and mathematical model formerly developed was used to describe the electrodialytic (ED) recovery of trisodium citrate. By performing several voltage–current, electro-osmosis and desalination tests, the main engineering parameters (i.e., the ion transport numbers in solution and membranes, effective solute and water transport numbers, effective surface area and resistances of membranes, and limiting electric current) of the ED process under study were assessed.As expected, the electric resistance of the cationic membranes (Rc) resulted to be about constant (0.11±0.02Ω) and independent of solute concentration, while that of the anionic ones (Ra) was not only greater than Rc, but also dependent on both the current applied and solute concentration. Moreover, in the ohmic region of the current–voltage curves Ra appeared to be a logarithmic function of the solution electric conductivity in the dilute compartment. On condition that the current applied was less than 2/3 of the limiting current for the cationic membrane (Ilim,c) the time course of the voltage applied to the ED stack when operating at a constant current of 0.75 or 1.5A was adequately predicted with a mean percentage error of ~20%.

Role of Electrical Conductivity of Spinning Solution on Enhancement of Electrospinnability of Polyamide 6,6 Nanofibers

Optimal conditions for electrospinning of uniform polyamide 6,6 (PA66) nanofibers were determined by the control of various parameters, such as polymer solution concentration, flow rate, tip-to-collector distance (TCD), applied voltage, and electrical conductivity of the polymer solution. An organic salt, benzyl trimethyl ammonium chloride (C10H16CIN, BTMAC), was added to the solutions for increase of electrical conductivity. When no salt was added to the PA66 solution, the uniform nanofibers were electrospun only at limited conditions, such as flow rate of 0.5 mL/h and electric fields greater than 2.0-3.5 kV/cm. In contrast, by the addition of BTMAC, range of optimal conditions for uniform nanofibers was expanded; uniform nanofibers were obtained at flow rate of 0.5-1.5 mL/h and electric fields greater than 1.3-1.6 kV/cm. This means that the electrospinnability of the nanofibers is improved by increasing electrical conductivity of the solutions. Furthermore, the addition of BTMAC affected the increasing of number average diameters and standard deviation of the nanofibers. On the other hand, the process variables, such as flow rate, TCD, and applied voltage, exerted little influence on the increase of diameters.

Isobutanol dehydrogenation on copper-containing bismuth vanadates

It is found that α, β, and Γ modifications of perovskites Bi4V2 − 2xCu2xO11 − δ (BICUVOX) exhibit different activities during catalytic transformations of isobutanol with a selectivity of isobutanal formation 85–100%. Data analysis shows that the site for the alcohol dehydrogenation reaction is the ion pair Cu2+-O2− with the highest activity for a highly conductive γ-phase. It is shown that the activation energy for aldehyde formation is lower for γ-phase of the catalyst by a factor of ten than that for its α-phase. It is concluded that step-wise Arrhenius dependences without changes in the activation energy for parallel alcohol dehydrogenation and dehydration reactions are related to changes in the conducting properties of the catalyst. Step change in activity was found at temperatures of 310 and 370° and corresponds to an increase of the solid solution electric conductivity.

Water quality effects on postharvest performance of cut calla, hydrangea, and snapdragon

Effects of water quality on water uptake, change in fresh weight, vase solution pH and electrical conductivity (EC) change, termination symptoms, and longevity of cut ‘Nicole Yellow’ calla (Zantedeschia L.), ‘White Extra’ hydrangea [Hydrangea macrophylla (Thunb.) Ser.], and ‘Admiral Pink’ snapdragon (Antirrhinum majus L.) were studied. Calla was tolerant of high water pH (8.1); vase life varied only from 9.2 d for acidic solutions (pH 3.2) to 10.1 d for solutions with intermediate pH (6.3). Calla had the longest vase life at an EC of 0.75dSm−1, whereas addition of floral preservative (Floralife Professional, Floralife, Walterboro, SC at 10mlL−1) was ineffective. Low solution pH (2.9–3.3), increasing EC (up to 2.5dSm−1), and use of floral preservative increased vase life of hydrangea. Increasing EC increased vase life of hydrangea from a low of 7.3 d to a high of 15.4 d at 2.5dSm−1, when floral preservative was used and from a low of 3.5 d to a high of 5.7 d at 4.0dSm−1 in distilled water. Vase solution pH of snapdragon had no significant effect on vase life or water uptake. Increasing EC increased vase life to a maximum of 14.8 d at 2.0dSm−1 with preservative and to 9.7 d at 3.0dSm−1 without preservative. Each species had differing responses to varying pH and EC levels; however, solution pH should be low, as high pH solutions either had no effect or reduced vase life, such as with hydrangea. EC of vase water for hydrangea and snapdragon should be approximately 2.0–2.5dSm−1, when preservatives are used and 3.0–4.0dSm−1 without, which is higher than most recommendations. Addition of preservative to vase solutions extended vase life of hydrangea and snapdragon, but did not affect calla.

Visual symptom and tissue nutrient contents in dry matter and petiole sap for diagnostic criteria of phosphorus nutrition for ‘Seolhyang’ strawberry cultivation

‘Seolhyang’ strawberries (Fragaria ananassa Duch.) were grown in a soilless substrate with fertigation solutions to evaluate the effects of six different P concentrations (0, 0.5, 1, 2, 4, and 6 meq·L−1) on the growth and nutrient contents in dry matter of above-ground tissue and petiole sap. The changes in electrical conductivity (EC) and pH of the root substrate were also investigated. Deficient and excess concentrations of phosphorus, such as 0 and 6 meq·L−1, seriously restricted the plant growth. These two treatments showed the least values in leaf number, plant height, leaf length and width, petiole length, and fresh and dry weights. The solution containing 1 meq·L−1 of phosphorus showed the greatest plant growth compared to the other treatments. The macro-element contents such as P, K, Ca, and Mg showed increased tendencies as P concentrations were elevated but, micro-elements such as Fe and Mn showed decreased tendencies in dry matter of above-ground tissue. When P concentrations were elevated, the pH and EC in the soil solution of root substrate decreased. Considering the crop growth and tissue nutrient contents, the P concentrations should be between 0.5 to 2.0 meq·L−1 and the P contents in the dry matter and petiole sap were 0.23 to 0.62% and 205 to 305 mg·kg−1.

Tomato Fruit Antioxidants in Relation to Salinity and Greenhouse Climate

A two-year study of antioxidants in greenhouse tomato was conducted. Plants were treated continuously with nutrient solution electrical conductivities (EC) of 2, 4, or 6 dS m⁻¹. Increasing EC reduced yield per plant and fruit size. Oxygen radical absorbance capacity (ORAC), lutein, β-carotene, lycopene, and vitamin C concentrations were evaluated in harvested fruit. ORAC and all antioxidants with the exception of lutein increased with EC. None of the 10 genes involved in antioxidant metabolism were affected by salinity in ripe fruit, but the expression of three of them (ZDS, CrtR-b1, and NCED1) varied with the stage of fruit development. Antioxidant concentrations were related to greenhouse climatic conditions. β-Carotene, lycopene, lutein, and vitamin C responded negatively to light and positively to temperature, whereas ORAC was unresponsive. Multiple regressions of antioxidants in relation to EC and climatic factors showed that antioxidants responded more strongly to light and temperature than to EC.

Real‐Time Soil Moisture and Salinity Profile Estimation Using Assimilation of Embedded Sensor Datastreams

Treated urban wastewater has been increasingly used for irrigation to increase crop production, but inadequate management of this marginal quality saline water cannot only reduce crop yield but also degrade soil. To increase sustainability, a sound irrigation policy based on real‐time soil states is needed to avoid the adverse effects from excess salinity in soils. In real applications, uncertain model inputs and soil heterogeneity are expected when a modeling approach is used. In addition, sensor measurement information is generally insufficient to characterize the state of the soil profile in detail. To overcome these limitations, a monitoring and modeling system assimilating embedded sensor datastreams into a hydrologic model to improve real‐time soil state estimates over the whole profile of interest is examined with a wastewater reuse system in Palmdale, CA. Experimental results show that under an unknown heterogeneous soil, the filtering scheme is able to describe the spatial variability of moisture and soil solution electrical conductivity in soils due to direct state estimation by assimilating moisture and electrical conductivity measurements and also due to improved soil hydraulic parameter estimates through the data assimilation framework. Two data withholding validation experiments were conducted to evaluate the added value of assimilating measurements. The spatial data withholding experiment demonstrates that state predictions at unobserved areas can be improved via the assimilation if the soil system is relatively homogeneous and effects from erroneous irrigation forcing are reduced. The temporal data withholding experiment indicates that a high update frequency can maintain the reliability of state estimation. Overall, this system can provide a more accurate soil characterization that could be used to optimize irrigation management to reduce adverse effects from wastewater reuse.

Variations in Species Composition of Moorland Plant Communities Along Environmental Gradients Within a Subalpine Zone in Northern Japan

Despite the ecological, conservation, and cultural significance of Japan’s alpine and subalpine moorland ecosystems, the patterns of species composition in plant communities in these ecosystems have not been fully described. The objectives of this study were to classify and describe the species composition of moorland plant communities and to examine the relationships between the classified community types and measured environmental variables within the subalpine zone of northern Japan. Plant communities were sorted into six types, whose strongest indicator species were Sieversia pentapetala, Schizocodon soldanelloides, Moliniopsis japonica, Vaccinium oxycoccos, Carex thunbergii, and Hosta sieboldii, respectively. The differences in species composition among these types were mainly related to the variations in soil solution pH and electric conductivity and in elevation and temperature. Each community type represented a unique combination of plant species, with some rare and endangered species. Describing and classifying the vegetation by providing indicators for a representative range of moorland community types should facilitate the identification and conservation of these valuable communities.