Influencing factors of seed long-distance dispersal on a fragmented forest landscape on Changbai Mountains,China

Seed long-distance dispersal(LDD) events are typically rare, but are important in the population processes that determine large-scale forest changes and the persistence of species in fragmented landscapes. However, previous studies focused on species dispersed via animal-mediated LDD, and ignored those dispersed by wind. The aim of this study was to assess the effects of canopy openness, edge, seed source, and patch tree density on the LDD of seeds by wind in forest. We collected birch seeds, a typical wind-dispersed species, throughout a larch plantation. We then assessed the relationship between birch LDD and each factor that may influence LDD of seeds by wind including distance to edge, canopy openness size, distance to mature forest, and the tree density of the larch plantation. We used univariate linear regression analysis to assess the influence of those factors on birch LDD, and partial correlations to calculate the contribution of each factor to LDD. The results showed that both canopy openness and edge had significant influences on birch LDD. Specifically, a negative relationship was observed between distance to edge and birch LDD, whereas there was a positive correlation between canopy openness size and LDD. In contrast, the distance to the mature forest was not correlated with birch LDD. Our results suggest that patch tree density could potently affect the probability of LDD by wind vectors, which provides novel and revealing insights regarding the effect of fragmentation on wind dynamics. The data also provide compelling evidence for the previously undocumented effect of habitat fragmentation on wind-dispersed organisms. As such, these observations will facilitate reasonable conservation planning, which requires a detailed understanding of the mechanisms by which patch properties hamper the delivery of seeds of wind-dispersed plants to fragmented areas.     

海坛岛海岸风沙特征及其发育

论述了海坛岛海岸风沙堆积物的沉积特征，对风沙地貌的基本类型进行了划分，分析其发育的基本条件和触发因素，研究其发育历史。     

九龙江口鳗苗溯河生态与资源研究

九龙江口Ｌｉ苗１９９４￣１９９６年溯河期为１９９４年１１月２０至１９９５年４月底。１９９５年１２月２０日至１９９６年５月底。鳗苗溯河期水温范围１１．５￣２２．５℃,盐度１．９８￣２５．００,透明度０．２￣１．１ｍ,九龙江口打石坑－嵩屿断面溯河鳗苗资源量１９９５年１９３ｋｇ,１９９６年２０８ｋｇ;海澄断面１９９５年３５ｋｇ,１９９６年５５ｋｇ。     

Circulations east of Taiwan and in East China Sea and east of Ryukyu Islands during early summer 1985

Ｃｉｒｃｕｌａｔｉｏｎｓ　ｅａｓｔ　ｏｆ　Ｔａｉｗａｎ　ａｎｄ　ｉｎ　Ｅａｓｔ　Ｃｈｉｎａ　Ｓｅａ　ａｎｄ　ｅａｓｔ　ｏｆ　Ｒｙｕｋｙｕ　Ｉｓｌａｎｄｓ　ｄｕｒｉｎｇ　ｅａｒｌｙ　ｓｕｍｍｅｒ　１９８５ＹｕａｎＹａｏｃｈｕ；Ｃｈｏ－ｔｅｎｇＬｉｕ；Ｐ...     

桑沟湾不同形态锰的分布、季节变化及影响因素

利用催化动力学分光光度法和两步提取法对2011年4月（春）、8月（夏）、10月（秋）和2012年1月（冬）桑沟湾海域溶解态无机锰(DIMn)和表层沉积物中的锰的含量进行测定。结果表明,桑沟湾4个季节（春季至冬季,后同）DIMn浓度呈现出近岸高、远岸低的分布特点,其平均浓度分别为(60.5±43.1) nmol/L、(42.0±30.5) nmol/L、(23.4±11.2) nmol/L和(18.2±13.5) nmol/L,呈现出明显的季节变化,即春季最高,夏季、秋季次之,冬季最低;与相邻的俚岛湾和爱莲湾相比,桑沟湾春季、夏季DIMn的浓度较高,秋季、冬季则没有显著性差异。桑沟湾表层沉积物中总Mn在4个季节的含量分别为(861±308) mg/kg、(915±322) mg/kg、(589±108) mg/kg、(653±185) mg/kg,表层沉积物中醋酸提取态Mn在4个季节的含量分别为(500±272) mg/kg、(502±232) mg/kg、(322±81) mg/kg、(345±91) mg/kg,两者均表现出近岸高、远岸低的分布特点。醋酸提取态Mn的含量在春季、夏季要显著高于秋季、冬季。悬浮颗粒物的吸附和浮游生物的利用是影响桑沟湾DIMn浓度与分布的重要因素。桑沟湾DIMn的源主要包括河流及地下水输送、大气输送、沉积物−水界面释放;汇主要包括养殖生物的清除、向黄海的输送等。简单箱式模型收支计算结果显示,桑沟湾DIMn的源略大于汇,表明除了养殖生物的清除和向黄海的输送,桑沟湾DIMn还存在其他汇。本研究的结果为桑沟湾DIMn的生物地球化学循环的深入认识提供了基础数据。     

台湾山地的雨影效应及其表现

台湾岛的雨量受台湾山地的雨影效应影响明显,各地各月随着风向的不同,雨量表现出很大的差异。福建沿海一线存在着一个雨量低值区,主要是由于该地带所处的地理位置及地形条件所决定,与台湾山地的雨影效应无关。     

西北地区生态环境现状和演化规律研究

利用20世纪70年代和90年代两个时段西北内陆地区的土地利用资料和遥感信息，对西北内陆地区的生态环境景观的20年的变化趋势进行了评价。通过评价，定量分析了西北内陆地区生态环境的总体变化趋势，研究了人工绿洲和天然绿洲的平衡比例关系以及与生态环境总体稳定的内在关系。这项研究对研究和确定生态环境保护合理阈值，维持绿洲稳定，保障当地社会经济的长远发展具有重要意义。     

水库重力测量检测非牛顿引力的实验数据分析新方法

本文提出水库重力测量检测非牛顿引力的实验数据分析新方法。利用近一天两重力仪的重力差值信号,基于同液面高度变化水体重力信号相等这一具有明显物理意义的准则,建立仪器零漂信号多项式系数矢量的矩阵方程,通过极大似然反演比较严格地计算漂移信号,并从中提取检测信号。实例计算结果表明:(1)当数据充分、漂移多项式阶数取值适当时,该方法完全有效;(2)在现有水库实验的设备和技术条件下,测定万有引力常数G对实验室值的偏离精度可达0.15％,优于矿井实验和先前水库实验的分析结果;若进一步改善水面高度测量,检测精度还可明显提高;(3)Hornberg水库实验重力仪G709在0.4％的精度范围内,未发现G对实验室值的偏离。     

基于模糊小波网络的伺服系统参数辨识研究

伺服系统大多是非线性系统,难以对其建立准确的控制模型,其位置、和速度检测信号易受干扰,而小波网络具有多分辨率特性和任意逼近能力。利用其非线性映射能力对系统的输入输出关系进行模拟,将小波网络和模糊规则结合对系统的位置和速度进行辨识,动态调整网络的权值W和模糊规则,将非线性映射的问题转化为求解系统最优解,从而产生一种新的系统辨识方法,并以永磁伺服系统为例,设计了辨识的结构模型和策略,实验表明该算法可以达到较高的系统控制要求。     

Preliminary study on the spore-pollen assemblages found in the Cenozoic sedimentary rocks in Grove Mountains, east Antarctica and its climatic implications

Glaciogene sedimentary rocks have been found in modem tills of the Grove Mountains, east Antarctica during the 1998 - 1999 Chinese National Antarctic Research Expedition （CHNARE）. Based on the lithilogic and sedimentary features, these sedimentary rocks are correlated with Cenozoic sedimentary strata of the Pagodroma Group in the neighboring Prince Charles Mountains and the Sorsdal Formation in VestFold Hills. Sedimentary clasts contain sparsely Late Tertiary spores and pollens, including ： Toroisporis （ Lygodiaceae）, Osmunda, Granulatisporites （ Pteridaceae？） , Polypodiaceae, Podocarpus , Araucariaceae, Artemisia , Rhus , Nothofagidites , Proteacidites （Proteaceae） , Quercus , Fraxinoipollenites （ Oleaceae ） , Oleoidearumpollenites（ Oleaceae ）, Operculumpollis, and Tricolpopollenites. Most of the pollen and spores contained in these samples originate from local sources according to the conditions of their preservations as well as correlations with the microfossil assemblages found in the neighboring areas. The majority of the pollen assemblages, as represented by Podocarpus and Nothofagus, belong to the Weddellian biogeocenose, however some exotic components from the old sedimentary basement rocks may have been included during erosion of the proximal ice sheet. If the source areas of glaciogenic sedimentary rocks that bear the pollen and spores are assumed to be local, or in the up glacier areas, the pollen assemblages in these samples might represent an inland flora during a warmer period of the ice-sheet evolutionary history. The finding of the Artemisia and Chenopodiaceae in the pollen assemblages implies that they may belong to late Tertiary （most probably Pliocene）. The absence of diatoms in the samples analyzed may indicate that there are no Cenozoic marine strata in the interior of the east Antarctica beyond the Grove Mountains. The significances of the finding of the Nothofagus in these pollen assemblages are discussed on the basis of current knowledge about the age, distribution and ecological conditions of this kind of fossils found in Sirius Group or other strata outcropped in Antarctica. As a preliminary conclusion, we think that the existence of the Cenozoic glaciogenenic rocks and their pollen assemblages present new evidence for a large scale glacial retreat history in Grove Mountains of east Antarctica, and thus support a dynamic East Antarctic Ice Sheet （EAIS）. This is consistent with the interpretations of Webb et al. （1984）.