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1.
Spake Rebecca Soga Masashi Kawamura Kazuhiro Cooke Robert S. Yamaura Yuichi Eigenbrod Felix 《Landscape Ecology》2020,35(5):1055-1071
Landscape Ecology - Functional responses to landscape heterogeneity are context-dependent, hampering the transferability of landscape-scale conservation initiatives. Japan provides a unique... 相似文献
2.
Kokoro Kikuchi Takumi Akasaka Yuichi Yamaura Futoshi Nakamura 《Journal of Forest Research》2013,18(5):389-397
The conservation of cavity trees in plantations is important for maintaining biodiversity because cavity trees are one of the forest attributes most strongly affected by forestry operations. We surveyed the occurrence of cavities at the tree-level and the abundance of cavity trees and the number of uses by secondary cavity users at the stand-level in natural and conifer plantation forests in Hokkaido, Japan. We classified cavities into two types by their formation processes: excavated and non-excavated. Excavated cavities were more common in dead trees than in live trees. Non-excavated cavities showed high occurrence in dead and live broad-leaved trees. The abundance of non-excavated cavity trees was two times greater than that of excavated cavity trees in natural forests, but, in plantations, excavated cavity trees were dominant. The abundance of non-excavated cavity trees was lower in thinned plantations than in not-thinned plantations. The number of cavity uses increased with the number of cavity trees, indicating the importance of maintaining cavity trees. Conifer plantations are established by removing native broad-leaved trees, which results in a lower abundance of non-excavated cavity trees in these locations. The conservation of broad-leaved trees is important for maintaining the current and future resource of non-excavated cavity trees in plantation forests, as is the conservation of dead trees, which showed a high occurrence of excavated cavities. 相似文献
3.
Mei Huang Dongdan Cai Yanhua Liu Jun Sun Jianjun Wang Chuanxiang Qin Lixing Dai Yamaura Kazuo 《Fibers and Polymers》2012,13(8):955-962
The hydrogels of atactic poly (vinyl alcohol) (a-PVA) and syndiotactic poly (vinyl alcohol) (s-PVA) with different blend ratios were prepared by freezing-thawing processes. The effect of s-PVA on gelation behavior of the blend was investigated in terms of gelation temperature (T gel) and hydrogel melting temperature (T gm). And swelling behavior, crystallization, thermal properties, morphology of the blend hydrogels were also studied. With the increase of s-PVA, T gel of the blend solution and T gm of the blend hydrogels increase. Both crystallinity and crystallite dimensions based on the XRD profiles are nearly monotonically increasing functions of s-PVA content. FTIR results indicate the number of hydrogen bonds raises with s-PVA increasing. DSC results demonstrate s-PVA favors improvement of hydrogels thermal stability. According to SEM images of hydrogels, the increase of cross-linking caused by s-PVA in the blend hydrogels results in denser structure, which in turn leads to increased gel fraction (G) and Hardness. 50/50 (a-PVA/s-PVA) blend hydrogel has a denser structure with EWC of 73.6 %, hardness of 22.8 HA and T m of 236.15 °C. The result indicates blending a-PVA and s-PVA is a useful method to form the hydrogel having good thermal stability and relative high degree of swelling. 相似文献
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5.
Yuichi Yamaura Hitoshi Tojo Yasumasa Hirata Kenichi Ozaki 《Journal of Forest Research》2007,12(4):298-305
It is important to conserve forest-dependent organisms not only in broadleaved forests but also in plantation forests. We
examined how surrounding forest areas affect forest bird assemblages inhabiting conifer plantations and broadleaved forests
in a rural landscape in central Japan. Surrounding forest areas were measured separately as plantation area and broadleaved
forest area within 200 m of each sampling site. We used hierarchical partitioning to analyze the effects of surrounding forest
areas and stand structures (stand height and understory coverage) on the occurrence of four species groups. We especially
focused on mature forest users that are most sensitive to loss of broadleaved forests. Occurrence of mature forest users inhabiting
plantation sites was positively affected both by plantation area and broadleaved forest area whereas the occurrence of mature
forest users inhabiting broadleaved forests was affected by stand height only. These results suggest that surrounding forest
areas were more important to mature forest users in plantations than in broadleaved forests. To conserve mature forest users,
increasing surrounding forest areas are important in plantations whereas increasing stand heights would be effective in broadleaved
forests. 相似文献
6.
AbstractHigh-yielding, waterlogged cultivations with considerable nitrogen input are widely practiced in Kyushu Island, Japan. Our objective was to determine the role of available phosphorus in relation to nitrogen and soil microorganisms on tomato growth in such systems. Tomato seedlings were grown in a pasteurized soil with ample KNO3 in addition to different amounts of sodium or potassium phosphates to assess effects of phosphorus on growth enhancement and water-use efficiency in the seedlings grown with copious soil water (>-0.7?kPa). Both monobasic and dibasic phosphates applied at 40?mM to near-saturated soil markedly promoted seedling growth when fertilized with 120?mM KNO3 or NH4Cl, but not in the soil without nitrogen. The final concentration of NO3- near the soil surface was maximized in the nitrated soil with no added PO43- but declined significantly when fertilized with any phosphates except Na2HPO4. No significant accumulation of NO3- was detected in the water-saturated bottom soils regardless of soil fertilization with any plant minerals. Increased seedling growth was accompanied by lower dry root/shoot ratios and marked increases in evapotranspiration efficiency. Such positive effects of PO43- were greater with NO3- than NH4+ but diminished with increased concentrations of Na+ up to 160?mM. Nonetheless, growth promotions by ample NO3- with PO43- were nearly negated in the non-pasteurized soil. Apparently, the activities of indigenous soil microbes were more significant than soil nitrogen and phosphorus in limiting the growth potential of tomato plants in near-saturated soils. 相似文献
7.
Triterpene alcohol and sterol ferulates from rice bran and their anti-inflammatory effects 总被引:6,自引:0,他引:6
Akihisa T Yasukawa K Yamaura M Ukiya M Kimura Y Shimizu N Arai K 《Journal of agricultural and food chemistry》2000,48(6):2313-2319
Six novel feruloyl esters of triterpene alcohols and sterols, viz., two trans-ferulates, cycloeucalenol and 24-methylenecholesterol trans-ferulates, and four cis-ferulates, cycloartenol, 24-methyelenecycloartanol, 24-methylcholesterol, and sitosterol cis-ferulates, besides five known trans-ferulates, cycloartenol (CAR), 24-methylenecycloartanol (24-MCA), 24-methylcholesterol, sitosterol, and stigmastanol trans-ferulates, and one known cis-ferulate, stigmastanol cis-ferulate, were isolated from the methanol extract of edible rice bran. These and eight other synthetic trans- and cis-ferulates of triterpene alcohols and sterols, along with the corresponding free alcohols, were evaluated with respect to their anti-inflammatory activity against 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation (1 microg per ear) in mice. All of the ferulates showed marked inhibitory activity, and their 50% inhibitory dose (ID(50)) was 0. 1-0.8 mg per ear. On the other hand, whereas two free triterpene alcohols, CAR and 24-MCA, showed strong inhibition (ID(50) 0.2-0.3 mg/ear), eight free sterols examined showed weaker activity (ID(50) 0.7-2.7 mg/ear) than their corresponding ferulates. 相似文献
8.
Bird responses to broad-leaved forest patch area in a plantation landscape across seasons 总被引:1,自引:0,他引:1
Yuichi Yamaura Susumu Ikeno Makoto Sano Kimiko Okabe Kenichi Ozaki 《Biological conservation》2009,142(10):2155-2165
Although plantation forests have widely replaced native forests worldwide, few studies have examined the effects of plantation forestry on organisms at the landscape level. In this study, we examined the effects of broad-leaved forest patch area (1.4–312 ha) on bird assemblages in a conifer plantation-dominated landscape during wintering and breeding seasons. We also surveyed birds in the plantation matrix and treated the patch area of the matrix as 0. We examined whether the detection rates of species changed suddenly across patch area (threshold) using segmented regression. We found that species richness increased with patch area in both seasons. Responses of detection rates to patch area varied and were categorized as follows: insensitive, linear increase and decrease, quadratic increase and decrease, concave and convex. Thresholds indicating that the detection rate suddenly increased above a certain patch area were found for two species only in the winter. Species responses varied more in the winter than in the breeding season. Certain ecological traits of species were consistently associated with the responses to patch area across seasons (migratory strategy, nesting substrate and foraging trait), while body weight was only associated in the winter. Because species richness and detection rates of many species were high in large patches, large broad-leaved forests (especially >40 ha) should be retained and restored with high priority. Additionally, bird responses to patch area in the winter should not be ignored because many species required large patches during the winter season. 相似文献
9.
Aimi Fuyuki Yuichi Yamaura Yuri Nakajima Nobuo Ishiyama Takumi Akasaka Futoshi Nakamura 《Urban Forestry & Urban Greening》2014,13(2):397-402
We examined factors that affect egg distributions of amphibians, which are currently declining globally, in urban areas. We counted the number of egg masses of two amphibian species (Hynobius retardatus and Rana pirica) in ponds in urban green spaces during two years (2011 and 2012) and investigated the effects of local and landscape factors on them. Forest area in green spaces and pond area had positive effects, and distance from continuous forests in the suburbs and the rate of pond shore protection had negative effects on the number of eggs. Among these factors, distance from continuous forests and pond area had strong effects on egg distributions. These results suggest the importance of water habitat size and the need for colonization by amphibians from surrounding continuous forests. To conserve urban amphibian assemblages, the preservation of ponds with sufficient area and continuous forests close to urban habitats would be important. 相似文献
10.
AbstractMany vegetable growers in Japan practice a unique waterlogged cultivation method with ample nitrogen (N) supply and microbial supplements, reporting vigorous plant growth, no soilborne diseases, and high yields. We simulated waterlogged soil conditions in greenhouse experiments to examine effects of soil pH and redox potential (Eh) as well as microbial influence on the growth of tomato seedlings. Soil pasteurization enhanced seedling growth whether the acidic, volcanic soil was waterlogged or well-drained. Among various antimicrobials, only soil treatment with polymyxin B improved shoot growth in nonpasteurized soil. The seedlings grew best in pasteurized acidic, waterlogged soil fertilized with ample potassium nitrate (KNO3), which maintained soil Eh above zero. In nonpasteurized soil, growth was severely stunted by raising soil pH progressively to 8.5 while Eh dropped to –194?mV. The results suggested that heat-sensitive Gram-negative soil bacteria and low soil Eh were key factors limiting the growth potential of tomato plants in waterlogged soils. 相似文献