Improving the accuracy of indirect methods in estimating leaf area index using three correction schemes in a Larix gmelinii plantation

Aims Woody materials and clumping effects are key error sources in estimating leaf area index (LAI) by optical methods. However, how to correct the error caused by woody materials has not reached consensus. The aims of this study are (1) to evaluate the accuracy of optical methods for estimating effective LAI (L_e) in a deciduous needle leaf forest stand, and (2) to develop a practical correction scheme to improve the accuracy of optical methods in estimating LAI.Methods L_ewas estimated by two indirect methods (i.e., digital hemispherical photography (DHP) and LAI-2000 plant canopy analyzer method (LAI-2000 method) in an annual maximum leaf area period in a Larix gmelinii plantation. Then, we developed three correction schemes to improve the accuracy of indirect methods in estimating LAI. Meanwhile, two direct methods (i.e., litter collection and allometry methods) were used to estimate LAI. Taking LAI from litter collection as a reference, we evaluated the effectiveness of three correction schemes and tested the influence of zenith angle ranges on the correction results.Important findings With zenith angle ranges of 0-45° (rings 1-3), 0-60° (rings 1-4), 45°-60° (ring 4) and 0-75° (rings 1-5), L_eobtained from DHP underestimated LAI from both litter collection and allometry by 19%-32% and 18%-29%, respectively. L_efrom LAI-2000 method with four zenith angles also underestimated LAI from both litter collection and allometry by 9%-30% and 8%-28%, respectively. Although the contribution of woody materials to LAI was overestimated in correction scheme A, it was effective in correcting L_efrom DHP with zenith angles of 45º-60º (ring 4), and also effective for L_efrom LAI-2000 method with zenith angles of rings both 1-3 and 1-4. Correction scheme B was all effective in correcting L_efrom DHP with four zenith angle ranges. Generally, correction scheme C was more effective than other two schemes in correcting L_efrom both DHP and LAI-2000 method with four zenith angle ranges. These results indicate that the zenith angle range is a key factor for determining the accuracy of optical methods in estimating LAI besides woody materials and clumping effects.     

中国兰科石豆兰属一新种

描述了中国石豆兰属Bulbophyllum一新种——天贵卷瓣兰(Bulbophyllum tianguii K.Y.Lang & D.Luo),并提供墨线图。该种产于广西乐业县,与富宁卷瓣兰B.funingense Z.H.Tsi & S.C.Chen外貌颇相似,但中萼片先端渐尖并具3 mm长的芒,侧萼片宽4~4.5 mm,花瓣先端渐尖并具1.5 mm长的芒,唇盘具2条肉质、具缘毛的纵脊,可与后者明显区别。     

白眉蝮蛇去整合素Adinbitor对Akt信号转导通路及对SSMC7721细胞增殖、迁移和凋亡的影响

研究白眉蝮蛇去整合素adinbitor对蛋白激酶B(Akt)通路信号分子的影响及对SSMC7721细胞增殖、迁移及凋亡的影响.采用MTT法检测adinbitor对SSMC7721细胞增殖的作用;Hoechst33258试剂盒检测adinbitor对SSMC7721凋亡的影响; Transwell 检测adinbitor对SSMC7721细胞迁移的作用;Western印迹检测adinbitor对信号分子Akt及磷酸化蛋白激酶B（p-Akt）、核因子κB（NF-κB）的抑制蛋白IκB-α及NF-κBp65的影响;分光光度法检测其对半胱天冬蛋白酶-3 （caspase -3）活性的影响.结果显示,adinbitor可显著抑制SSMC7721细胞的迁移和增殖(与对照组比较,P＜005),促进凋亡. 在浓度梯度adinbitor作用下,Akt 表达量基本不变,但其磷酸化受到抑制.细胞浆内IκB α表达增加,细胞核内NF-κBp65表达减少,caspase-3活化倍数平均在2.24～3.85之间,以上作用均呈现剂量依赖性.结果说明,adinbitor可通过抑制Akt相关信号转导分子的作用而抑制SSMC7721细胞增殖和迁移,并促进其凋亡.     

沉痛悼念尹长民教授

惊闻吾师仙逝,大脑嗡的一片混乱,心中如遭重锤!我不敢相信这个噩耗,迫不及待向人求证,但现实是残酷的.泪水无声地划过脸颊,此情此景,天若有情,天亦落泪!     

黑蛋巢菌属新种新变种和中国新记录种

本文报道了黑蛋巢菌属Cyathus的三个新种、一个新变种和一个新记录种,它们分别是:四川黑蛋巢菌C.sichuanensis Liu et Y.M.Li,关帝山黑蛋巢菌C.guandishanensisLiu et Y.M.Li,云南黑蛋巢菌C.yunnanensis Liu et Y.M.Li,五台山黑蛋巢菌垣曲变种C.wutaishanensis Liu,Shangguan et Yuan var.yuanquensis Liu et Y.M.Li和栗褐黑蛋巢菌C.badius Kobayasi。模式标本除C.yunanensis Liu et Y.M.Li保存在中国科学院微生物研究所标本室外,其余均保存在山西大学真菌标本室。     

黑蛋巢菌属新种新变种和中国新记录种*

本文报道了黑蛋巢菌属Cyathus的三个新种、一个新变种和一个新记录种,它们分别是:四川黑蛋巢菌C.sichuanensis Liu et Y.M.Li,关帝山黑蛋巢菌C.guandishanensisLiu et Y.M.Li,云南黑蛋巢菌C.yunnanensis Liu et Y.M.Li,五台山黑蛋巢菌垣曲变种C.wutaishanensis Liu,Shangguan et Yuan var.yuanquensis Liu et Y.M.Li和栗褐黑蛋巢菌C.badius Kobayasi。模式标本除C.yunanensis Liu et Y.M.Li保存在中国科学院微生物研究所标本室外,其余均保存在山西大学真菌标本室。     

广西叶蝉—新属新种(同翅目:叶蝉科)

本文以一种珍贵的叶蝉新属种奉献周尧教授,敬佩他为昆虫事业所建树的丰功伟绩,感谢他对后学的悉心培育和无私支援。 模式标本保存在北京农业大学昆虫标本室,其中1对副模分藏西北农业大学昆虫博物馆。 周叶蝉属Chouious,新属 属模式种:Chouious tianzeus Yang 属名释意:Chou-Io(周尧)+us(读:无私,人名元音结尾+us,指定为阳性属名)。 属征:体狭长,体坚硬密布大刻点,体腹面多柔毛及蜡粉。     

α－天冬氨酰二肽酶基因的高表达和产物回收

构建了α天冬氨酰二肽酶基因（ｐｅｐＥ）与载体ｐＢＶ２２０连接的高表达重组质粒（ｐＢＶＰＥＰ,４３３７ｂｐ）。转化大肠杆菌后,目的基因表达为两种形式的产物,即细胞质中可溶性蛋白（～７５％）和包含体蛋白,共占细菌总蛋白的３０％左右。ＳＤＳＰＡＧＥ分析温敏诱导的表达蛋白,可以观察到约２７ｋＤａ的高表达蛋白条带,与提纯的酶带一致。用不同于以往的萃取包含体蛋白的方法,回收了包含体中９５％以上的表达蛋白。     

浙江天台山甜槠群落研究

以分布以浙江省天台山的甜槠群落为对象,分析了群落的特征和性质。甜槠群落中,甜槠的优势突出,呈单优势群落。群落垂直结构复杂,可分为乔木层、灌木层、草本层,变有一定数量的层间植物。乔木层的物种多样性指数偏低,这与特定生境所形成的单优势群落有关。各样地间的植物种类具有较高的相似性,群落内种类组成相对一致。群落内优势种群甜槠、木荷的年龄结构属稳定型或增长型,它们在各样地的分布格局均呈集群分布。