华北地台早古生代竹叶状灰岩岩石特征及成因研究进展

砾屑灰岩在华北地台寒武系-奥陶系广泛发育,竹叶状灰岩只是其中一种,且所指范围界限模糊,常与其他类型的砾屑灰岩伴生在一起。古代陆表海提供了砾屑灰岩广泛发育的环境基础。潮坪和潮下开阔海是陆表海广泛发育的基本地貌单元,也是砾屑灰岩形成的重要场所。古板块运动表明,寒武纪华北地台处于低纬度地区,符合古风暴频发的要求。风暴及潮汐流是砾屑灰岩形成的主要动力。另外,成岩过程中的压实和固结脱水也是板条状砾屑的重要成因。条带状薄层灰泥石灰岩与泥岩及泥质灰岩的频繁互层是发生破碎并形成砾屑的物质基础。华北地台砾屑灰岩具有多种成因,可以按照砾屑的颜色特征、形态及磨圆程度、砾屑灰岩的支撑结构、充填物的类型等进行区分并进行成因分析。     

蜜桔叶片中八种元素的对比分析及其对果实品质的影响

研究了火焰原子吸收光度法连续测定干灰化法处理的南丰蜜桔叶片样品中Ca,Mg,Co,Ni,Cu,Zn,Mn,Fe等八种中微量元素的方法.实验表明,本方法连续测定植物中的微量元素含量,具有准确度高、操作简易、设备使用费用低等特点.通过对比分析,探讨不同品质南丰蜜桔叶片中微量元素的含量分布及差异,测定结果可用于指导桔农对微肥的施用.结果表明,在所研究的元素中,品质差的南丰蜜桔叶片中严重缺乏Ca,Mg两无素,因此,建议桔农追施硫酸钙和硫酸镁.     

叶片辐射传输模型PROSPECT 理论研究

综述植物叶片辐射传输PROSPECT 模型的理论,并对其理论来源PLATE 模型作了扼要介绍。进一步研究叶片结构、叶片光学吸收参数和叶片反射率、透射率之间的非线性关系,给出如何用单层致密叶片迭代来表示多层非致密叶片的反射率、透射率。讨论了Stokes 光学系统理论及其在模型理论中的应用,并用复向量的方法证明其各向同性光学介质中反射率和透射率递推关系式。表明PROSPECT 模型基于良好的物理模型,在满足假设条件下,能够准确模拟叶片的反射率和透射率。     

Impact of episodic herbivory by the tamarisk leaf beetle on leaf litter nitrogen and stem starch content: A short communication

Tamarisk (Tamarix spp.) has in recent decades come to dominate riparian corridors throughout much of the western U.S. The implementation of biological control, utilizing the tamarisk leaf beetle (Diorhabda spp., particularly Diorhabda carinulata), has focused attention and research on this method for Tamarix suppression. Researchers are just beginning to understand how herbivory by Diorhabda affects Tamarix physiology and nutritional dynamics. The purpose of this study was to investigate whether herbivory by D. carinulata altered leaf litter nitrogen and stem starch content, and if so, how such alteration varied across a gradient of herbivory chronosequence. Leaf litter and stem analysis showed significantly higher levels of both nitrogen and stem starch content in trees that had experienced herbivory by the leaf beetle. However, there were no significant differences in nitrogen or stem starch content based on years of beetle herbivory. Higher levels of nitrogen in leaf litter from beetle-affected trees may be a result of herbivory-induced desiccation and foliar mortality prior to the translocation of nitrogen back into plant reserves. Additionally, higher stem starch may be a result of either phloem damage reducing the translocation of photoassimilates, or an increase in the shunting of carbohydrates to the site of new leaf growth. Finally, the lack of correlation between years of herbivory and both leaf litter nitrogen and stem starch may indicate that as of yet there have not been sufficient defoliation events to yield anticipated host plant impact.     

Rainfall interception by sand-stabilizing shrubs related to crown structure

On the edge of the Tengger Desert in northern China,revegetation has changed the landscape from moving dunes to stabilized dunes covered by shrubs,which further modifies the pattern of rainfall redistribution.To study rainfall interception loss by shrubs and its relationship to rainfall properties and crown structure,throughfalls passing through crowns of Artemisia ordosica Krash.and Caragana korshinskii Kom.were measured using nine PVC cups under the canopy of each of the two shrubs during 73 rain events over a three-year period,with total rainfall of 260.9 mm.Interception losses of gross rainfall by A.ordosica and C.korshinskii account for 15% and 27% of the total on a crown area basis,and 6% and 11% on a ground area basis,respectively.Individual throughfall(T) and interception(I) were significantly related to rainfall amount(Pg),duration(D),and intensity(R).Ratios of throughfall to rainfall(T/Pg) and interception to rainfall(I/Pg) were not only significantly related to Pg,D,and R,but also to shrub species,and interactions of species with crown volume(CV) and leaf area index(LAI).Under most rain events,interceptions by C.korshinskii with greater CV and LAI were significantly higher than those by A.ordosica,and more rainfall interception occurred at locations closer to the stems of the two shrubs.For C.korshinskii,I/Pg had a significant positive linear relation with CV and LAI,while T/Pg had a significant negative linear relation with them.CV has a greater influence on T/Pg and I/Pg than does LAI.Using a regression method,canopy water storage capacities are estimated to be 0.52 and 0.68 mm,and free throughfall coefficient to be 0.62 and 0.47 for A.ordosica and C.korshinskii,respectively.     

植物叶蜡单体氢同位素重建非洲和东亚大陆古降水:亮点与难点

植物利用周围环境中的水分进行光合作用合成有机质, 其叶蜡氢同位素记录了源水中的氢同位素组成, 被认为是重建古水循环的替代性指标。然而从源水(降水)到合成叶蜡脂类化合物, 降水中的氢同位素会发生多步分馏作用。本文综述了对氢同位素分馏造成影响的因素及其校正方法, 通过有效的数据处理, 叶蜡氢同位素可以比较直接地反映降水的氢同位素组成。由于在热带地区降水氢同位素受"雨量效应"影响较大, 所以可以较好地反映降水量变化, 在非洲大陆常被用于重建水循环和气候变化; 在东亚大陆,"雨量效应"不再那么显著, 水汽的来源可能在影响降水氢同位素组成的过程中也起到了重要作用。     

基于多角度遥感的植被指数与叶面积指数的线性关系研究

以辐射传输方程PROSAIL为基础,模拟不同观测天顶角和不同叶面积指数(LAI)下的植被冠层光谱。利用模拟的冠层光谱构建3种常用的植被指数,并分析不同观测天顶角下叶面积指数变化对3种植被指数的影响。结果表明,MSR能较好解决由于LAI变化而引起的饱和现象。观测天顶角为-30°时,3种植被指数与叶面积指数的线性关系较30°和0°时好。     

基于大气环流的稻纵卷叶螟气象预测模型

基于1980-2016年全国稻纵卷叶螟逐年发生面积、产量损失资料、逐月74项大气环流特征量以及南方15省(区、市)地面气象资料,采用因子膨化处理技术、Pearson遥相关分析法和逐步回归分析法,筛选对中国稻纵卷叶螟发生面积率有显著影响的大气环流因子,构建中国稻纵卷叶螟发生面积率的多时相动态大气环流预测模型,探讨大气环流对中国稻纵卷叶螟发生的可能影响机制。结果表明:46项大气环流因子与稻纵卷叶螟发生关系密切,副热带高压类、极涡类环流因子是中国稻纵卷叶螟发生面积率的主导影响因子。建立的中国稻纵卷叶螟发生面积率年前、年后3-10月的月动态预测模型历史拟合较好,对2015年、2016年1月初及3-10月各月初外延预报两年平均准确率分别达86.6%,90.5%,91.8%,93.4%,93.4%,94.0%,94.0%,94.3%,95.4%。关键环流特征因子、当年气候年型和稻区5-9月气象条件对中国稻纵卷叶螟的发生程度具有较好的指示效应,稻纵卷叶螟发生面积率较大的年份主要出现在干暖年和湿暖年;干冷年型常导致稻纵卷叶螟发生面积率偏小。     

鸡毛菜叶龄估算模式及其应用

根据对不同播种期鸡毛菜的抽样测定资料,采用植物生长模型结合鸡毛菜生产期间９￣２５℃的有效积温对叶龄进行估算,叶龄估算的绝对误差在０．５叶之内。     

秋茄落叶分解失重过程的季节变化和滩面差异

秋茄红树林不同季节落叶分解失重速率研究表明:落叶的干重损失速率是夏>秋>春>冬。就失重过程而言,最高的失重速率和季节间最明显的分解速率差异都出现于分解初期,淋溶作用很可能是引起这一分解特征的重要原因。落叶在林地滩面外滩(中潮带).中滩和内滩(高潮蒂)分解28d时的失重率分别为53.4%、44.8%和48.9%,即外滩>内滩>中滩。中潮带比高潮带具有较高的潮浸频度和滩面潮湿度,使得落叶在中潮带的分解快于高潮带。