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柳杉人工林于24年生时,经不同带宽之行列疏伐处理后,疏伐带栽植扁柏、红桧、台湾杉、香杉4种林木,历经21 a后,目前之成活率,不同带宽成活率差异不显著;但树种间成活率差异显著,以台湾杉最高59%,香杉最低31%。而其胸径和树高之生长,不同疏伐带间部分树种之胸径、树高生长差异不显著;但树种间胸径、树高生长差异极显著。保留带之柳杉胸径、树高之生长明显大于对照区,而材积现存量则对照区仍大于疏伐区。在定期平均生长方面,胸径生长在疏伐13 a后,疏伐效果已减缓;而材积生长则在疏伐7 a后即明显超越对照区。行列疏伐保留带之留存木,在疏伐后6 a间,有较严重之风害,因此建议未来进行疏伐时,留存带应该扩大宽度,建议宽度在20 m以上,以减少风害。在林下地被植物调查方面,全区共调查到97种植物,Shannon多样性指数达到1.78,而Simpson多样性指数则为0.66。在不同的疏伐处理下,保留带与对照区的种类丰富度均低于疏伐处理后的区域,反映出疏伐作业会造成不同的林下环境条件,进而影响地被植物的组成多样性。在林下天然更新树木的调查成果方面,全区共调查到66种、2 010株树木,平均植株密度为941株hm2,Shannon多样性指数达到2.92,Simpson多样性指数则为0.89。在不同的疏伐处理下,天然更新树木的组成多样性已接近显著差异。天然更新树木的数量上,保留带与对照区的林木密度均显著高于疏伐区域,反映出过去的各项森林施业过程(疏伐、下木栽植、抚育等)会实质地影响到林木的天然更新状态。 相似文献
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用非注山毛豆叶丙酮提取物或鱼藤酮点滴处理菜粉蝶幼虫，出现畸形幼虫和畸形蛹，对畸形幼虫和畸形蛹的真皮细胞和内外表皮分别进行了超显微结构观察，发现鱼藤酮及其类似物影响昆虫旧表皮的分解和新表皮的合成是导致虫体畸形的主要原因，并对畸形蛹体壁的几丁质，粗脂肪，粗蛋白的含量进行测定，结果表明处理组与对照组存在明显的差异。 相似文献
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密山虎林地区位于中国黑龙江省的东部,是穆陵河冲积平原的森林沼泽生草灰化土和潜育化草甸土区,这个区域的土壤发育和特性是与生成环境密切的联系着。一、密山虎林地区的自然条件1.气候根据现有的记载,本区年雨量在600毫米左右,大部雨水在4—10月降落,因此植物生长期内雨水较为充沛。年平均温度2—4℃,绝 相似文献
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大豆紫斑病是华北和东北的大豆生产中重要病害之一。华东和西南地区也有这一病害的报告[3]。虽然这是一种重要病害,可是对于它的病原菌生物学的研究尚不多。 相似文献
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CHIH-HAO HSIEH CHIH-SHIN CHEN TAI-SHENG CHIU KUO-TIEN LEE FENG-JEN SHIEH JIA-YI PAN MING-AN LEE 《Fisheries Oceanography》2009,18(2):102-117
We investigated environmental effects on larval anchovy fluctuations (based on CPUE from 1980 to 2000) in the waters off southwestern Taiwan using advanced time series analyses, including the state-space approach to remove seasonality, wavelet analysis to investigate transient relationships, and stationary bootstrap to test correlation between time series. For large-scale environmental effects, we used the Southern Oscillation Index (SOI) to represent the El Niño Southern Oscillation (ENSO); for local hydrographic conditions, we used sea surface temperature (SST), river runoff, and mixing conditions. Whereas the anchovy catch consisted of a northern species ( Engraulis japonicus ) and two southern species ( Encrasicholina heteroloba and Encrasicholina punctifer ), the magnitude of the anchovy catch appeared to be mainly determined by the strength of Eng. japonicus (Japanese anchovy). The main factor that caused the interannual variation of anchovy CPUE might change through time. The CPUE showed a negative correlation with combination of water temperature and river runoff before 1987 and a positive correlation with river runoff after 1988. Whereas a significant negative correlation between CPUE and ENSOs existed, this correlation was driven completely by the low-frequency ENSO events and explained only 10% of the variance. Several previous studies on this population emphasized that the fluctuations of larval anchovy abundance were determined by local SST. Our analyses indicated that such a correlation was transient and simply reflected ENSO signals. Recent advances in physical oceanography around Taiwan showed that the ENSOs reduced the strength of the Asian monsoon and thus weakened the China Coastal Current toward Taiwan. The decline of larval anchovy during ENSO may be due to reduced China Coastal Current, which is important in facilitating the spawning migration of the Japanese anchovy. 相似文献
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降雨是导致土壤冲蚀的主要原因,而通用土壤流失公式(USLE)为目前世界上应用最广泛的土壤流失模式,式中之降雨冲蚀指数直接反映了降雨对土壤侵蚀的程度,为评估土壤侵蚀状况的重要因子之一.研究以基隆、新竹、嘉义、高雄、宜兰、花莲、台东等雨量测站资料之历年雨量记录建立各月之降雨冲蚀指数,所采用之记录为1975-2000年之降雨资料,并建立月降雨冲蚀指数及月降雨量关系式.由于气候变迁导致的降雨变化将影响土壤冲蚀之估算,而不同时间之雨量资料所推估的降雨冲蚀指数精度不同,又必须配合气候变迁模拟之时间尺度,故本研究以月雨量及月降雨冲蚀指数为基础探讨之.采用IPCC公告之B2情境下的大气环流模型(GCMs)模拟基隆、新竹、嘉义、高雄、宜兰、花莲、台东等测站未来降尺度月雨量变化.推估基隆、新竹、嘉义、高雄、宜兰、花莲、台东等测站未来短期、中期、长期之月降雨冲蚀指数,以供推估土壤流失量,可以发现各模型之平均值未来土壤冲蚀量在B2情境约-80%～+60%. 相似文献
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1950年在河北徐水县調查白菜病害时會見到矮縮而有坏死斑型的病害,一般称之为"抽瘋"或"孤丁";为害率在3%左右。同年在山东历城調查时亦曾發現比类病害;为害率在5%以下。当地农民認为病害的發生与栽培甘藍有关,而且与蚜虫有关。河北白菜区到处有这一类型的發現,但为害的情况不严重。1952年东北大白菜栽培区普遍發生这种病害,使菜株矮縮不长,損失極大;一般称之为"弧丁"。 相似文献
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YANG Shoushen SUN Xiaoshuang QIU Yunfei YANG Fei TANG Jie LIAN Wenjian HUANG Cuiqin CHIU Hungchuan 《畜牧兽医学报》1956,51(9):2216-2226
The differentially expressed proteins between sporulated oocyst and unsporulated oocyst of Cystoisospora suis strains were screened and compared. In this study, the C. suis infection model of piglets were established and a quantitative proteomic analysis between sporulated oocyst and unsporulated oocyst of C. suis were conducted by iTRAQ labeling and LC-MS/MS. Part of the iTRAQ results were validated by qRT-PCR. Total 174 proteins were identified, among which 40 proteins were differentially expressed, 38 proteins were upregulated and 2 proteins were downregulated. The differentially expressed proteins were mainly involved in metabolism, antibiotics biosynthesis, secondary metabolites biosynthesis and glycolysis/gluconeogenesis pathways. The results of this study provide reference for elucidating the developmental mechanism of C. suis sporulated oocyst and facilitated discovering a new biomarker for C. suis. 相似文献