Soil erosion and overland flow in Japanese cypress plantations: spatio-temporal variations and a sampling strategy     

Takanori Sato  Nobuaki Tanaka  Anand Nainar  Koichiro Kuraji  Mie Gomyo  Haruhiko Suzuki 《水文科学杂志》2020,65(13):2322-2335

ABSTRACT

Many studies have focused on soil erosion in unmanaged Japanese cypress plantations because the sparse understory vegetation and litter covering the forest ground enhance soil erosion. In this study, soil erosion, litter, and overland flow measurements were conducted over 14 months to identify the spatio-temporal variation and examine the optimal sample size. Fifteen traps (each 0.25 m wide) were installed in line along the bottom of a 15-m-wide slope. Soil erosion and overland flow had large spatial variations as compared to litter. The temporal coefficient of variation of soil erosion and overland flow was highest during dry seasons, while smaller during wet seasons. The random sampling analysis showed that the rate of decrease in spatio-temporal variation became moderate as the sample size increased beyond six. This result indicated that the optimal sample size was five, the total width of which was equivalent to about 8% of the monitored slope width.  相似文献   

INTERDECADAL SEA LEVEL VARIATION AT THE JAPANESE COAST AND LARGE SCALE CLIMATE STATE   总被引：2，自引：1，他引：2  

崔茂常 《中国海洋湖沼学报》1995,13(4):303-309

Thirty years of monthly mean anomalies of sea level(SL) at 15 Japanese coastal stations, sea sur-face temperature (SST) and sea level pressure (SLP) in or over the northern Pacific were analyzed bycanonical correlation analysis (CCA) to study the relationship between the interdecadal SL variationand large scale climate state. Given two time-varying fields this technique identifies the pair ofspacial patterns with optimally correlated time series.The results show that there are two important air-sea interactive processes in the extratropicalPacific region for the variation of the SL at the Japanese coast on interdecadal scale. One is theocean heating or cooling of the atmosphere over the Kuroshio extension region, which results in ahuge SLP anomalous vortex with planetary spacial scale big enough to change the global climate. An-other is the large Kuroshio meander phenomenon controlled by the large-scale wind-stress curls oneyear earlier in the adjacent region of the Hawaiian Islands. The first process im  相似文献   

Urban space, ethnic community, and national belonging: the political landscape of memory in Little Tokyo     

Hillary Jenks 《GeoJournal》2008,73(3):231-244

The “Little Tokyo” neighborhood of Los Angeles was the center of pre-internment community life for Japanese immigrants and their children and is still considered the symbolic home of later generations of Japanese Americans in Southern California. Drawing on three years of ethnographic research in Little Tokyo, I explore in this article how contemporary Japanese Americans have used and transformed this ancestral landscape in order to express, contest, and formalize collective memories of the Japanese American experience, particularly with regard to their place in the national body politic. Historical narratives inscribed at many places in Little Tokyo, both informal and institutional, project a narrative of sacrifice, suffering, and redemption in the context of internment and military service, articulating neatly with mainstream American tropes of overcoming hardship as a process of ‘earning’ citizenship and its benefits. However, such narratives are also contested by alternative interpretations and representations of these spaces that describe a special role for Japanese Americans in making demands of their government, rather than just sacrifices to it. The resulting debates, disagreements, and even occasional consensus around constructions of nation, identity, community, and belonging are rooted in the ‘sacred ground’ of Little Tokyo, gathering meaning and persuasive power through their connection to a symbolically dense site of shared memory. The multiple memory projects of this landscape reveal how Japanese Americans have envisioned their relationship to the concept of America, to each other, and to other communities with shared experiences in a diverse metropolis.

Hillary JenksEmail:

  相似文献   

Assembling “Japantown”? A critical toponymy of urban dispossession in Vancouver,Canada     

Trevor James Wideman  Jeffrey R. Masuda 《Urban geography》2018,39(4):493-518

Geographic scholarship in critical toponymy has highlighted the importance of place naming as a form of discursive power within processes of urbanization. This paper builds on such literature and advances a novel theory of toponymic assemblage to interpret findings from a participatory research project in the Downtown Eastside of Vancouver, Canada. We foreground neighborhood history in the form of a Japanese Canadian enclave and its wartime uprooting and dispossession, and trace the historical antecedents of a resurrected toponymy of “Japantown” that has appropriated and renarrated Japanese Canadian history to facilitate further rounds of dispossession. Using a genealogical method, we highlight three “moments” of Japanese Canadian uprooting, return, presence, and activism, demonstrating how toponymies are assembled in place in heterogeneous and historically contiguous ways. This approach expands on current research in critical toponymy, offering a novel methodology for exploring the enrolment of toponymy, discourse, and materiality in the formation of place.  相似文献   

桂林暴雨分析与预报     

王艳兰 《气象研究与应用》2003,24(2):10-14

通过分析历年汛期各类暴雨过程的日本数值预报产品资料,统计出桂林历年暴雨过程的天气形势和数值产品要素特征,并检验了日本短期预报产品对各类暴雨的预报能力。然后通过对预报桂林暴雨的各种日本数值产品临界值的分析,挑选出一些相关性较好的要素产品预报因子,统计出桂林局部暴雨过程和致洪暴雨过程预报指标,最后对大暴雨过程预报指标及连续性暴雨过程的数值产品特征作了初步分析。  相似文献   

Effect of estradiol-17β on pituitary-thyroidal axis of Japanese eel (Anguilla japonica)     

Qu Xiancheng  Masaki Nagae  Sinji Adachi  Kohei Yamauchi 《海洋学报(英文版)》2001,20(4):585-596

In teleost sPeCies, it is well accepted that estradiol--l75 (E2 )is generated from ovarian fOl-licles stimulated by pituitary gonadOtropins (GTH) (Nagahama, l987). FUrthermore, E2 canstimulate hepatic vitellngenesis and elevate plasrna yOlk protein precursor vite1lOgenin, totalCa and W levels in several teleosts (KorSgaard and Petersen, l976, l978; Whiteheadet al., l978; Elliott et al., l979; Pertersen et al., l983; Wallace, 1985; tapigliati etal., 1999). On the other hand, many stud…  相似文献   

Reaction of juvenile flounder to grid separators   总被引：1，自引：0，他引：1  

Matsushita  Yoshiki; Fujita  Kaoru; Ikegami  Naoya; Ohata  Satoshi 《ICES Journal of Marine Science》2004,61(7):1174-1178

  相似文献   

Combined effects of ethanol and cinnamaldehyde in the Japanese medaka embryo-larval assay (MELA)     

Haasch ML  Ford AW 《Marine environmental research》2004,58(2-5):175-179

The Japanese medaka (Oryzias latipes) was used in the medaka embryo-larval assay (MELA) to determine possible adverse developmental effects of ethanol and the spice component, cinnamaldehyde (CAD). Fish may be exposed to waterborne ethanol and a variety of natural products from non-point sources or leaks during ethanol use as a fuel and from point source processing plant effluents. Consumption of ethanol during human pregnancy is known to cause fetal alcohol syndrome (FAS), a collection of birth defects including craniofacial abnormalities thought to be caused by the generation of free radicals during ethanol metabolism by both alcohol and aldehyde dehydrogenase(s). Fish are also susceptible to FAS (Dasmahapatra et al., meeting abstract). The activity of aldehyde dehydrogenase is inhibited by CAD [Biochem. J. 282 (1992) 353-360; Biochem. Pharmacol. 45 (1993) 1621-1630], and CAD is known to cause developmental abnormalities in the rat [Food Chem. Toxicol. 27 (1989) 781-786]. Therefore, the combined effects of treatment with both ethanol and CAD would be expected to produce additive or greater than additive effects in the MELA assay. Medaka were exposed to ethanol at 100 mM, CAD at 10, 1.0, 0.67 or 0.50 mM, to ethanol and CAD combined, or were non-treated controls. Ethanol at 100 mM was without effect. CAD alone at 10 mM and 1.0 mM was lethal by 1 dpf. Embryos exposed to 100 mM ethanol and 0.67 mM CAD exhibited cardiovascular and pigmentation defects and delayed hatching. Embryos exposed to 0.50 mM CAD alone had less severe cardiovascular problems as compared to the combined ethanol and CAD treatment. Taken together the results indicate that the combined effects of ethanol and CAD are greater than the individual effects and indicate the need to monitor effluents in fish nursery areas to protect natural fish populations. Supported by PHS/NIH ES07929.  相似文献   

注射外源激素对养殖雄性牙鲆精巢发育的影响     

温海深  宋海霞 《中国海洋大学学报(自然科学版)》2007,37(2):229-234

雄性牙鲆在人工养殖条件下,1年可达到性成熟,精巢属于典型的叶型结构。生殖细胞经历了精原细胞、初级精母细胞、次级精母细胞、精子细胞和精子5个发育阶段;精小叶间存在Leydig细胞,小叶内存在Sertoli细胞。牙鲆精子属于原始类型,可明显地区分为头部、中段和尾部,与大多数硬骨鱼类相似;精子头部无顶体,其内含有大小不等的囊泡,尾部具有典型的“9 2”结构。注射外源LHRH-A2或hCG,对牙鲆的精巢发育和排精没有起到促进作用,可能是由于一次注射的外源在血液内很快被清除,或操作胁迫使血浆皮质醇含量升高抑制了下丘脑-垂体-性腺轴的正常功能。建议在进行牙鲆人工催产时,最好采用激素埋植法,在对亲鱼进行操作时,应将其麻醉,增加激素的作用效果。  相似文献   

卵胎生硬骨鱼褐菖精子发生的超微结构研究   总被引：4，自引：0，他引：4  

尤永隆  林丹军  钟秀容 《热带海洋学报》2002,21(1):70-75

研究了卵胎生硬骨鱼褐菖 Sebastiscus marmoratus精子发生的过程.褐菖的精子发生经历了初级精原细胞、次级精原细胞、初级精母细胞、次级精母细胞、精子细胞等阶段,最终形成精子.在初级精原细胞和次级精原细胞阶段,细胞核中释放出拟染色体.拟染色体分布于精原细胞和前期Ⅰ的初级精母细胞的细胞质中.在前期Ⅰ以后的初级精母细胞、次级精母细胞和精子细胞中,拟染色体已消失.在初级精母细胞阶段,前期Ⅰ至末期Ⅰ的细胞形态变化明显.在前期Ⅰ的偶线期,同源染色体开始配对并形成联会复合体;在粗线期,联会复合体完全形成;在双线期,联会复合体开始解体.  相似文献