Variation in microhabitat use of the threatened spotfin chub (Erimonax monachus) among stream sites and seasons

Abstract – The spotfin chub Erimonax monachus is a rare cyprinid fish endemic to the Tennessee River drainage, and it is federally listed as threatened in the USA. Microhabitat use of spotfin chubs was studied via stream snorkelling in the Emory River watershed, Tennessee, one of the last remaining populations of this species. We used a Bayesian generalised linear mixed model to evaluate microhabitat covariates related to the presence/absence of spotfin chubs among eight stream sites across three seasons (early summer, late summer and fall). In general, spotfin chubs were more likely to be present in microhabitats characterised by boulder/bedrock substrates, medium to high velocity, and medium depth (typical of the run habitat). However, the patterns were not necessarily consistent among seasons or stream sites, due partly to interactions between microhabitat and macrohabitat covariates. Specifically, spotfin chubs were more selective of bedrock and boulder substrate at smaller stream sites where they were less abundant, and they were more selective of higher velocity at warmer stream temperatures (early and late summer). Our data indicate that spotfin chubs may exhibit flexible microhabitat use to some extent, and their microhabitat use may differ by macrohabitat characteristics such as stream size and water temperature. This study provided a refined understanding of microhabitat use of spotfin chubs and suggests that effective conservation of this declining species should identify and protect available suitable habitat across space and time.     

A weeding-duration model for <Emphasis Type="Italic">Larix kaempferi</Emphasis> plantations in Hokkaido,northern Japan

In this study, a weeding-duration model for Larix kaempferi plantations was developed that employs a generalized linear model. The number of years that weeding is necessary is the response variable, and elevation, slope, maximum snow depth, annual precipitation, geological type, soil type, site index, slope aspect, and vegetation type are explanatory variables. Among the explanatory variables, geological type, soil type, slope aspect, and vegetation type are categorical data. We assumed a Poisson distribution for the response variable. The link function was log. Among the models that could be developed from these variables, we chose the model with the smallest Akaike’s information criterion (AIC). The weeding-duration model can be written as follows: years that weeding is necessary = Exp (−0.0172833 × site index + 0.0014053 × maximum snow depth (cm) + 1.7417731). The results of this study imply that weeding of Larix kaempferi plantations is needed for more years as the maximum snow depth increases and fewer years as the site index increases. This model is useful for cost–benefit analyses of afforestation or reforestation with Larix kaempferi.     

Emissions of trace gases (CO2, CO,CH4, and N2O) resulting from rice straw burning

Emissions of trace gases (CO₂, CO, CH₄, N₂O) resulting from rice straw burning were measured by using the open chamber method. The carbon contained in rice straw was mainly released to the atmosphere as CO₂. The percentage of CO₂-C emitted in total C in rice straw was in the range of 57–81%, followed by CO-C (5–9%). The percentages of CH₄-C and N₂O-N in total C and N in rice straw were in the range of 0.43–0.90 and 1.16–1.50%, respectively. In the case of the rice straw which had been left in the field for a period of one month after harvest, emission of imperfect combustible gases such as CO and CH₄ during burning increased slightly, while that of perfect combustible gas, CO₂, was reduced. The amount of CH₄ emission from rice straw burning was comparable to that from paddy fields.     

Properties and classification of volcanic ash soils around Lake Kuwanuma on the eastern footslope of Mt. Funagata in Miyagi prefecture,northeastern Japan

One of the developments in recognition of soil properties and different soils is from morphological to analytical. With an incorporation of analytical data, transitional soils can be systematically named using a key-out order as well as typical soils. Our major objective was to evaluate soils with multiple forming processes such as andosolization, podzolization, etc., using soil analytical data, selecting a small area having different soil names based on soil morphological properties. According to a local soil map, Ando soils, Brown forest soils (Dark) and Wet and Dry podzols soils are adjacently distributed around Lake Kuwanuma on the eastern footslope of Mt. Funagata in Miyagi prefecture, northeastern Japan. We studied the morphological, chemical and mineralogical properties of these soils and classified them according to the recent Comprehensive Soil Classification System of Japan (CSCSJ), United States Department of Agriculture Soil Taxonomy (ST) and the World Reference Base for Soil Resources (WRB). The elevation of Lake Kuwanuma is 780 m above sea level and a plateau is located next to a steep slope on the western side of the lake. Three pedons were sampled from the northern side of Lake Kuwanuma, and 3 additional pedons were sampled from the plateau. The average difference in elevation between these two groups of pedons was 229 m. All 6 pedons were classified as Andosols in CSCSJ, Udands in ST and Andosols in WRB. Thus, andosolization was the dominant soil-forming process throughout the study area. The major modification of Andisols in the study area was caused by forest vegetation. Of the 6 pedons sampled, three were classified as Fulvudands in ST and had the Fulvic prefix qualifier in WRB. Furthermore, weak podzolization was suggested on the basis of soil profile observations. One pedon on the plateau had a Bs horizon, which satisfied the spodic horizon requirements of ST. Thus, weak podzolization, especially on the plateau, was another accessory characteristic in the present study area. The nearby distribution of Podzols soils and Ando soils in the local soil map may be explained by differences in temperature, leaching intensity and other factors. A podzolic subgroup of Andosols/Udands was desired to express the properties of pedons on the plateau in the lower categories of the recent soil classification systems.     

Factors controlling accumulation and decomposition of organic carbon in humus horizons of Andosols

Andosols often accumulate soil organic matter (SOM) in large amounts. To investigate the factors controlling the stability and lability of organic carbon (OC) in humus horizons of Andosols, we selected 19 A horizon samples (surface and subsurface horizons) from the Field Station of Tohoku University including areas where benchmark soil profiles of non-allophanic Andosols are distributed. We determined the soil properties possibly controlling the OC accumulation, such as pH(H₂O), 1 M KCl-extractable aluminum (KCl-Al), pyrophosphate-extractable Al and iron (Al_p, Fe_p), acid oxalate-extractable silicon (Si_o), total OC, water-extractable OC, and humified OC. To evaluate the OC mineralization, we measured the soil respiration rates in a laboratory for non-treated, neutralized (CaCO₃, Ca(OH)₂ and NaOH), and nutrient applied (KH₂PO₄, (NH₄)₂SO₄) soil samples. Statistical analyses, including a path analysis, showed that the Al_p and pH(H₂O) values are directly related to the OC concentration (P?<?0.01 and P?<?0.05, respectively). There was a significant negative correlation (P?<?0.01) between the soil respiration rates of the non-treated samples and the ratios of the humified OC to total OC, showing that the humification of the SOM was definitely related to the OC stability. Effects of the chemical treatments to the soil respiration rates were greater in the surface horizon samples with an abundant labile OC than those in the subsurface samples. Neutralization affected the soil respiration rates more significantly than the nutrient application. Among the neutralization treatments, the liming materials more effectively increased the respiration rates. This was probably due to an increase in the lability of the humified OC by liming.     

Genesis and characteristics of a red-yellow soil derived from Gabbro,Northern Kyushu

There are few pedological investigations of the soils derived from basic rocks in Japan. The object of this paper is to offer fundamental information concerning the genesis and analytical characteristics of a Red-Yellow soil derived from a basic rock (gabbro) of which silica content is approximately 44 per cent.     

Dispersion of humic allophane soils with supersonic vibration

The difficulties in dispersing volcanic ash soils of Japan and New Zealand have been considered to be due to the association or aggregation of allophane (3, 5, 7–10). In particular, MIYAZAWA (9) has obtained evidence that stable microaggregates of Humic Allophane soils derived from volcanic ash have been formed by dehydration of allophane. Recently, several investigators (2, 4, 6, 8, 9, 12) have pointed out that ultrasonic vibration is effective in dispersing the fine particles of soils. With respect to the applicability of supersonic vibration to the particle-size distribution analysis of Humic Allophane soils, MIYAZAWA (9) stated that the maximum dispersion, as measured by the clay content, was obtained only with supersonic vibration using an acidic medium. KOBO and OBA (8) reported that calgon (sodium hexametaphosphate) as a dispersing agent was successfully applicable to most Humic Allophane soils, but the use of HCI was necessary for some highly allophanic subsoils, and that the effect of supersonic vibration on dispersion of the soils is attributed to the breakdown of aggregates larger than 20 microns in diameter. They also recommended a mixture of 10g of soil and 50 ml of water and 20 min. exposure for a supersonic vibrator (10 Kc, 300 W). With respect to the applicability of vibration treatment in the particle-size distribution analysis of Humic Allophane soils containing volcanic glasses in abundance, some apprehension may be entertained about the breakdown of primary minerals, especially of volcanic glasses (9, 10).     

Continuous in vitro culture of erythrocytic stages of Babesia gibsoni and virulence of the cultivated parasite

Babesia gibsoni infected erythrocytes were collected from the blood of an experimentally infected dog. The parasite isolated could be continuously cultivated in vitro, with an average parasitemia of 18.2 +/- 2.4% on day 3 of culture, in RPMI-1640 medium supplemented with 7.5% normal dog serum in a humidified atmosphere containing 5% CO(2) at 37 degrees C. The parasites in the original culture were morphologically similar to those found in the peripheral blood of dogs, however, on the 4th generation of subculture, the large oval parasites, erythrocytes including many parasites and extracellular parasites were frequently observed. The B. gibsoni isolate was injected to the dog to test its infectivity after maintained in vitro for 738 days at the 214th subculture. The cultivated parasite did not cause a severe clinical sign in the dog.