江苏宜兴龙池山现代植被表土孢粉的初步研究

江苏宜兴龙池山森林自然保护区表土花粉分析结果表明,表土孢粉植物群主要以栎属(Quercus)、松属(Pinus)、青冈属(Cyclobalanopsis)、栲属(Castanopsis)/柯属(Lithocarpus)、栗属(Castanea)占优势的木本植物组成,混生有枫香属(Liquidambar)、杨梅属(Myrica)、冬青属(Ilex)、女贞属(Ligustrum)、紫树属(Nyssa)、盐肤木属(Rhus)、黄连木属(Pistacia)等亚热带常见植物类型。研究区不同海拔高度的表土孢粉组合特征基本反映了当地现今的植物构成、植被面貌及其垂直分布规律。结合长江三角洲及其周边地区其他代表性表土花粉资料,首次提出以常绿阔叶木本植物与落叶阔叶木本植物含量之比(E/D),并结合重要优势、标志木本植物科属,初步识别和确立各地带性森林植被的表土花粉指标,为这一地区开展第四纪古植被和古气候等孢粉研究提供参考性依据。     

Relationships among recent Alpine Cladocera remains and their environment: implications for climate-change studies

Our objective was to assess the potential of Cladocera from mountain lakes for climate reconstruction. We related Cladocera from surface sediments of Alpine lakes (1,502–2,309 m asl) to 29 abiotic environmental variables using statistical methods. The environmental dataset included water chemistry, lake depth, and bi-hourly water-temperature logs, which were used to assess mean monthly water temperatures, dates of freezing and breakup, spring and autumn mixing. We found 14 different Cladocera of the families Bosminidae, Daphniidae, and Chydoridae. Lakes without Cladocera (eight lakes) were cold and/or ultra-oligotrophic, whereas lakes with planktonic and littoral Cladocera (19 lakes) were warmer and/or less oligotrophic. Lakes with only littoral Cladocera (18 lakes) had intermediate water temperatures/trophy. Changes in Cladocera assemblages were related to changes in climate, nutrients, and/or alkalinity. We found a climate threshold at which Bosminidae disappeared in 95% of the lakes. For climate-change research, we propose studying Cladocera along transects that include climatic thresholds. Guest editor: Piet Spaak Cladocera: Proceedings of the 7th International Symposium on Cladocera     

广东鼎湖山自然保护区森林景观的动态模拟研究

在遥感和GIS系统支持下,以1991年和1999年两个时期的Landsat-TM合成影像为基础,利用马尔科夫模型,模拟鼎湖山自然保护区森林景观的动态演变。结果表明:常绿阔叶林面积增加,除水域外,其它面积相应减少,到达稳定期,区域内大多为常绿阔叶林,少量的混交林,其它类型几乎消失。这个趋势是和该地区森林的演替规律相符的,但是这种结果对维持保护区内的景观多样性是不利的。     

濒危植物秦岭冷杉群落数量特征及其动态

对石人山自然保护区秦岭冷杉群落特征和动态进行了研究,结果表明:秦岭冷杉群落共有种子植物61种,分属27科40属,群落垂直结构简单,可分为乔木层、灌木层和草本层。秦岭冷杉和华山松种群大、中胸径的个体占绝对优势,幼苗、幼树较少,属于衰退种群;湖北花楸小、中胸径的个体占优势,属于进展种群。通过聚类分析,将秦岭冷杉群落分为5个群丛类型:①秦岭冷杉 湖北花楸-山刺玫-结缕草群丛;②秦岭冷杉 华山松-秀雅杜鹃-藜芦群丛;③秦岭冷杉 血皮槭-黄刺玫-野菊群丛;④秦岭冷杉 华山松-箭竹-牛蒡群丛;⑤秦岭冷杉 锐齿栎-箭竹-水芹群丛。5个群丛类型均处于动态变化中,种群恢复应实行就地保护,减少人为干扰,促进天然更新。     

邢台西部山地种子植物区系地理研究

邢台西部山地位于河北太行山脉南段,共有野生种子植物93科、393属、823种。该区系地理成分复杂,具有明显的温带性质,也有一定的热带亲缘,中国特有种丰富。运用相似性系数,对该区与其它8个山地植物区系成分进行了比较分析。结果表明:邢台西部山地植物区系与太岳山和中条山区系相似性较高,与东灵山、小五台山、雾灵山和伏牛山的关系次之,与长白山和神农架的相似性较低。     

陕西黄龙山林区褐马鸡繁殖季节中午卧息地选择

2006年5—6月,在陕西黄龙山腹地北寺山林区采取样线法对褐马鸡(Crossoptilon mantchuricum)中午卧息地的选择进行了研究,共观察到28个褐马鸡的卧息地。褐马鸡对林型、坡向和地理特征有明显的选择性,多偏向针叶林、山脊和半阴半阳坡,回避阔叶林、山坡、阴坡和阳坡。对中午卧息地坡位没有明显的选择性。褐马鸡中午卧息地具有坡度小、与林间道路与居民点的距离远、灌丛平均高度较低、灌木密度较小、草本均高较小、乔木层植物盖度以及草本层植物盖度较大等特征。对各种生境因子的主成分分析表明,前6个特征值的累积贡献率达到74.05%,可较好地反映褐马鸡中午卧息地生境特征。根据载荷系数绝对值大小将褐马鸡中午休息地生境选择影响因子分别命名为地理因子、隐蔽度因子、人类活动干扰因子和灌丛密度因子。     

武汉桂子山地区冬季鸟类群落结构及多样性研究

2005年11月～2006年3月,对武汉桂子山地区冬季鸟类群落进行了调查,共记录鸟类44种,隶属10目22科。有国家Ⅱ级保护鸟类2种,湖北省重点保护鸟类16种;留鸟32种,冬候鸟11种,旅鸟1种,留鸟构成了冬季鸟类的主体;该地区冬季鸟类密度为4．30只／hm^2,物种多样性指数为2．6477,均匀性指数为0．6997。居民点、乔灌林、绿地和水域生境中,乔灌林鸟类多样性最高,数量最多。     

Distribution of cephalopods in the upper epipelagic northwestern Bering Sea in autumn

In the northwestern Bering Sea in autumn, the epipelagic cephalopod community was represented by the boreal fauna, and was found to be composed of three families and nine species of the order Teuthida: Gonatidae (Berryteuthis magister, Boreoteuthis borealis, Gonatopsis japonicus, Gonatus madokai, Gonatus kamtschaticus, Gonatus onyx, and Gonatus pyros), Chiroteuthidae (Chiroteuthis calyx) and Onychoteuthidae (Onychoteuthis borealijaponica). Two pelagic gonatid species (B. borealis and G. kamtschaticus) dominated the cephalopod community in the upper 50 m. The distribution patterns of B. borealis and G. onyx were associated with diel vertical migrations of these squid. The distribution of two distinct size groups of G. kamtschaticus suggested ontogenetic migration of larger squid to deeper layers, and adds to previous data suggesting that this species may be a heterogeneous assemblage. Demersal B. magister rarely occurred in the surface waters. The occurrence of maturing O. borealijaponica in the southern marine area indicated that these were occasional seasonal migrants from the ocean. The occurrence of juvenile C. calyx suggested that these squid may conduct vertical forage migrations from deep waters to the surface layers.     

青藏高原东南缘贡嘎山地区大气总汞时间序列分析及其影响因子

使用Tekran 2537A大气汞自动分析仪对中国科学院贡嘎山高山生态系统观测试验站磨西基地站(102°72′E29°92′N)进行了为期1a的大气总汞(TGM)高时间分辨率观测。研究区域的平均TGM浓度为(4±1.38)ng m-3(N=57310),高于全球大气总汞背景值1.5~2.0ng m-3。不同季节表现出相似的日变化模式,即白天相对夜晚具有较高的TGM浓度,最大TGM浓度出现在中午,最小值出现在日出前,春季和夏季日变化高峰值出现时间比秋季和冬季早1~2h。以冬季TGM浓度最高,为(6.13±1.78)ng m-3;夏季最低,为(3.17±0.67)ng m-3。观测期间不同风向间TGM浓度无显著差异。相关分析表明,TGM浓度与温度、饱和水汽压、降水量、紫外辐射、大气压有显著相关性,这种相关性随季节而变化。贡嘎山地区大气汞浓度主要受局地源的影响和调节。     

Silvopastoralism in the Alps: Native plant species selection under different grazing pressure

To evaluate the suitability of wood pastures as a managing tool in subalpine regions it is essential to know more about the influence of grazing on the ground vegetation. This study assessed native plant species selection by cattle at different stocking rates, feeding habits and site preferences of cattle. Based on the results, conclusions concerning the value of silvopastoral systems in the Alps were drawn. A field study on six different wood pasture areas, grazed by cattle at different stocking rates, was accompanied by an experiment on three adjoining areas of 0.51 ha each, stocked with either three, six, or nine heifers. Plant species were recorded in plots of 20 cm × 20 cm before and after grazing, and the intensity of grazing on each species was assessed. At low stocking rates, grasses and tall species were most intensely grazed, while at higher stocking rates the intake of forbs and small species increased. Since no relationship was found between nutritional value and species preference, other factors such as accessibility of a plant seem to be important for the feeding preferences of cattle. The preference for grasses at low and medium stocking rates suggests that an increased growth of forbs might lead to an increase in plant species diversity.