日本虎杖覆盖对连作的影响——日本西阿瓦陡坡土地农业系统传统耕作评价

禾本科物种(例如银草、芦苇)在日本传统的地膜覆盖农业中普遍使用,西阿瓦地区是全球重要的农业遗产系统(GIAHS)所在地。传统上,这里的农民使用银草覆盖农业土壤。但当地农民从长期的经验中了解到,日本虎杖覆盖更适合该地区茄科作物的种植。目前尚不清楚日本虎杖覆盖物为何对茄科作物的种植有益。在本项研究中,我们假设日本虎杖覆盖物可能会有效避免连续种植马铃薯的危害。因为过去每年都会种植两次本地马铃薯,因此,我们调查了日本虎杖覆盖对连续种植马铃薯以及番茄种植后对马铃薯产量的影响。在2018年进行的田间试验中,我们首先在连续马铃薯栽培的土壤和未耕种的土壤中比较了日本虎杖覆盖、银草覆盖和无草覆盖(对照)对马铃薯产量的影响,结果表明日本虎杖覆盖减少了马铃薯产量的降低程度。其次,我们比较了番茄种植后的土壤和未耕种的土壤中的虎杖覆盖和无草覆盖对马铃薯产量的影响,结果再次表明了日本虎杖覆盖减少了马铃薯生长和产量下降的程度。这些发现表明用日本虎杖覆盖有助于避免连续种植马铃薯的风险。     

Peristerite compositions in quartzofeldspathic schists, Franz Josef-Fox Glacier Area, New Zealand

Plagioclase compositions vary from An_0.1–2.5 to An₃₂ with increasing grade in chlorite zone to oligoclase zone quartzofeldspathic schists, Franz Josef-Fox Glacier area, Southern Alps, New Zealand. This change is interrupted by the peristerite composition gap in rocks transitional between greenschist and amphibolite facies grade. Oligoclase (An_20-24) and albite (An_0.1–0.5) are found in biotite zone schists below the garnet isograd. With increasing grade, the plagioclase compositions outline the peristerite gap, which is asymmetric and narrows to compositions of An₁₂ and An₆ near the top of the garnet zone. In any one sample, oligoclase is the stable mineral in mica-rich layers above the garnet isograd, whereas albite and oligoclase exist in apparent textural equilibrium in adjacent quartz-plagioclase layers. The initial appearance of oligoclase in both layers results from the breakdown of epidote and possibly sphene. Carbonate is restricted to the quartz-plagioclase rich layers and probably accounts for the more sodic composition of oligoclase in these layers. The formation of more Ca-rich albite and more Na-rich oligoclase near the upper limit of the garnet zone coincides with the disappearance of carbonate and closure of the peristerite gap. Garnet appears to have only a localized effect on Ca-enrichment of plagioclase in mica-rich layers within the garnet zone. The Na-content of white mica increases sympathetically with increasing Ca-content of oligoclase and metamorphic grade. Comparison of the peristerite gap in the Franz Josef-Fox Glacier schists and schists of the same bulk composition in the Haast River area, 80 km to the S, indicates that oligoclase appears and epidote disappears at lower temperatures, and that the composition gap between coexisting albite and oligoclase is narrower in the Franz Josef-Fox Glacier area. It is suggested that a higher thermal gradient (38-40°C/km) and variations in Si/Al ordering during growth of the plagioclases between the two areas may account for these differences. In the Alpine schists the peristerite gap exists over a temperature and pressure interval of about 370-515°C and 5.5-7 kbar (550-700 MPa) P_H2O.     

High‐resolution lithostratigraphy and organic carbon isotope stratigraphy of the Lower Triassic pelagic sequence in central Japan

After the severest mass extinction event in the Phanerozoic, biotic recovery from the extinction at the Permian–Triassic boundary required approximately 5 my, which covers the entire Early Triassic. It is important to obtain information on the superocean Panthalassa, which occupied most of the world ocean, to explore paleoenvironmental changes during the Early Triassic at the global scale. In order to establish the continuous lithostratigraphy of pelagic sediments in Panthalassa during the Early Triassic, high‐resolution reconstruction of the Lower Triassic pelagic sequence in Japan was conducted for the first time based on detailed field mapping and lithostratigraphic correlation in the Inuyama area, central Japan. The reconstructed Early Triassic sequence is approximately 9.5 m thick, consists of five rock types, and is divided into eight lithological units. For the reconstructed continuous sequence, measurement of carbon isotopic composition of sedimentary organic matter (δ¹³C_org) was carried out. Stratigraphic variation of the δ¹³C_org value shows large‐amplitude fluctuations between ?34.4 and ?21.0‰ throughout the sequence. In order to establish a higher resolution age model for the reconstructed Lower Triassic pelagic sequence, we correlated δ¹³C_org records in the Inuyama area with high‐resolution isotopic profiles of carbonate carbon (δ¹³C_carb) from shallow‐marine carbonate sequences in southern China based on the similarity in general variation patterns with age constraints by radiolarian and conodont biostratigraphy. The result provides a high‐resolution time scale for the pelagic sequence of Panthalassa during the Smithian and Spathian. The age model suggests a drastic increase in sedimentation rate during the late Smithian, which should have been caused by the increase in terrigenous input to this site.