Termite borings in Early Cretaceous fossil wood, Isle of Wight, UK     

J.E. Francis  B.M. Harland 《Cretaceous Research》2006,27(6):773-777

A pellet-filled boring in fossil wood is described from the Early Cretaceous Wessex Formation (Barremian), Isle of Wight. The cylindrical boring, approximately 1 cm in diameter, is filled with carbonaceous pellets with a hexagonal shape, preserved within a matrix of pyrite. Features of the boring suggest that it was made by termites that bored into the wood, either when the tree was alive or in the early stages of decay on the forest floor. This evidence of termite activity complements previous records of termite wing fossils and faecal pellets in Wealden sediments and is evidence for social behaviour in Wealden insects. This is one of the oldest records of termite borings in wood.  相似文献   

Tree roots — Methodological review and new development in dating and quantifying erosive processes     

Holger Grtner 《Geomorphology》2007,86(3-4):243-251

Exposed roots have been used in Dendrogeomorphology since the 1960s to determine erosion rates. This was done by using the root axis as the relative position of the former soil layer and then relating this measure to the age of the root in order to quantify the amount of soil erosion over time. Recently, wood anatomical research revealed the possibility of determining the first year of exposure of roots due to specific anatomical changes within the respective annual ring. As a consequence, using exposed roots that are still in contact to the soil surface, it is possible to reconstruct the size and position of the root at the time of exposure. Consequently, a new equation is presented to calculate the thickness of the eroded soil layer allowing a detailed reconstruction of erosion rates. The technique also helps to determine if the root was exposed by erosional processes or just by its ongoing secondary growth without any erosion involved.  相似文献   

New plesiosaurian specimens (Reptilia,Plesiosauria) from the Upper Cretaceous (Turonian) of Goulmima (Southern Morocco)     

《Cretaceous Research》2018

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红树植物秋茄次生木质部生态解剖学的比较   总被引：4，自引：0，他引：4  

林益明  林建辉 《台湾海峡》1998,17(2):219-223,T001

本文研究了不同纬度秋茄（Ｋａｎｄｅｌｉａ ｃａｎｄｅｌ）次生木质部的组织结构及数量特征。秋茄的导管多为梯纹导管。随着纬度的升高,温度下降,各分布区导管分子长度和导管直径呈现下降的真挚深圳福田的秋茄导管分子长度、导管直径均是最大是个例外＿;穿孔板横隔的数目也纬度的升高而减少;盐度高（３３）造成福建云霄竹塔的秋茄低导管颁布频率、低单管孔率、低双管孔率;秋茄的射线分布频率随着纬度的升高而减少（海南东寨港  相似文献   

The use of woods-run chips in filter socks to control erosion and sedimentation during petroleum development in the Appalachian Basin     

《国际泥沙研究》2019,34(6):608-615

Filter socks frequently are used for erosion and sediment perimeter control during oil and gas development activities in the Appalachian Basin of the United States. Regulations specify the use of composted wood material for sock construction. This specification, as opposed to non-composted or fresh wood chips (woods-run), has created inefficiencies during well site construction. Rather than use fresh wood chips created during site construction, composted chips must be procured and used as filter sock media for erosion and sedimentation mitigation. If woods-run chips could be used as filter sock media instead of composted chips, there could be a significant reduction in energy/capital costs, truck traffic, and disposal costs. The primary objective of this research project was to compare the effectiveness of woods-run material versus traditionally composted wood chips in controlling sediment transport as well as other chemical and physical parameters in a laboratory setting. No significant differences in pH (5.96 versus 6.02) or conductivity (0.029 dS/m versus 0.035 dS/m) were found in sediment laden water filtered through woods-run versus composted chips, respectively. However, chip particle sizes were outside the allowable limits for composted sock media, and moisture content also was outside the specified limits for woods-run chips. Nitrate (NO₃) concentrations were significantly higher in woods-run, while phosphorus (P) and potassium (K) concentrations were greater in composted chips; however none of the N,P, or K concentrations were above the regulatory requirements. Finally, no difference in the filtering efficiency or time was found between woods-run and composted material. The laboratory results indicate that current regulations allowing the use of woods-run chips in all but the highest quality watersheds is justified.  相似文献   

波纹龙虾雄性生殖系统的解剖学与组织学研究   总被引：1，自引：0，他引：1  

刘慧玲  李长玲  黄翔鹄  曹伏君 《广东海洋大学学报》2009,29(3):1-5

用解剖学和组织学方法研究了波纹龙虾雄性生殖系统,结果表明,波纹龙虾雄性生殖系统由精巢、输精管及生殖孔三部分组成。精巢横切面一般为圆形,外被一层结缔组织被膜,内部为许多圆形或椭圆形的生精小管,生精小管间充满了网状结缔组织。精子的发生经历精原细胞、初级精母细胞、次级精母细胞、精细胞和精子5个阶段。输精管管壁由外到内依次由结缔组织被膜、结缔组织、肌肉层和上皮细胞组成,管壁上的柱状上皮细胞、肌肉组织及结缔组织一起向管内延伸形成纵褶突。管壁和纵褶突上的柱状上皮细胞向管腔中分泌嗜酸性黏液。精荚呈管状,在中段输精管形成,并储存在管腔的黏液中。  相似文献   

榄李属红树植物叶片结构及其生态适应     

李元跃  潘文  黎中宝  林鹏 《海洋科学》2010,34(7):72-76

研究了采自海南东寨港(19°54′N,110°20′E)榄李属的红榄李(Lumintzera littorea)和榄李(Lumintzera racemosa)的叶片结构及其生态学意义。榄李属红树植物的叶片解剖结构特征基本相同,都具有适应海滩环境的结构——叶片为完全等面叶,没有内皮层结构,海绵组织特化为贮水组织等;叶的解剖结构差异可能是榄李属红树植物生态隔离现象的原因,其结构差异可为种间鉴定提供依据。  相似文献   

The structures of eye and surrounding tissues of Longman＇ s beaked whale, Indopacetus pacificus     

祝茜  山田格  李响 《中国海洋湖沼学报》2008,26(2):219-221

Observations were made on one eye from a Longman's beaked whale Indopacetus pacificus,which was probably one of the least known extant cetaceans.The whale died shortly after swimming aground on the coast in the Nishikata Beach,Sendai-shi,Kagoshima-ken Prefecture,Japan,on July 26,2002.It was a mature female with body length 6.45 m.This paper documented the basic structural characteristics of her visual organ of the whale in order to better understand this animal.  相似文献   

光裸星虫消化系统的解剖学和组织学研究     

操向文  王庆恒  黄若男  杜晓东 《广东海洋大学学报》2009,29(3):6-10

运用解剖学和组织学方法研究光裸星虫(Sipunculus nudus)消化系统结构。结果表明,光裸星虫消化系统由消化道和直肠盲囊组成,消化道可分为口、食道、下行肠、上行肠、直肠和肛门。口四周由具摄食作用的辐射状触手围绕。消化道管壁由黏膜层、黏膜下层和浆膜三层结构组成,黏膜层具有大量皱褶,黏膜下层和浆膜层中分布有大量颗粒细胞;无连续的肌肉层,只在黏膜下层内散布着数量不等的肌纤维。直肠盲囊细长,连接于上行肠末端,囊壁无分泌细胞,囊内充满黄色黏稠液状物质。  相似文献   

International wood trade and forest change: A global analysis     

Thomas Kastner  Karl-Heinz ErbSanderine Nonhebel 《Global Environmental Change》2011,21(3):947-956

Throughout history, humans have transformed natural forests into agricultural land, settlement areas and managed forests. Studies on the dynamics of forest change are one of the mainstays in land change science. The forest transition theory offers a powerful tool to analyze changes in human interference with forests. At the national level, a range of factors have been found to influence a country's forest change. The role of international wood product trade has, however, rarely been studied based on empirical data. We offer a global assessment of how this trade helps shape observed forest change, by relating forest stock change to net trade of wood products for the period 1997-2007 and by localizing the origin of wood consumed in a given nation. For many nations, traded wood products have a relevant impact on the course of ongoing forest transitions. We develop a general typology of how wood product trade can influence forest change and place various nations within this framework. We find that many wealthy nations with returning forests seem to accelerate this return by importing wood products. These imports appear to be provided by two main types of wood exporters: (a) by wealthy countries with low population densities and stable forests and (b) by relatively poor countries with declining forests, employing increasing population and welfare levels. We discuss these findings in the light of general theories on land use transitions and forest change and conclude by highlighting implications for national forest policies and global environmental governance, aiming at reducing negative impacts of wood products and enhancing the positive role they can play in replacing more fossil fuel intensive products.  相似文献