松辽盆地南部梨树断陷登楼库组孢粉组合

本文系统地研究了松辽盆地南部梨树断陷登楼库组孢子花粉化石,计３９属６０种,描述１０属１６种,根据孢粉组合特征及对包括被子植物花粉在内的主要孢粉类型地质地理分布的分析,认为登楼库组时代应为早白垩世Ａｌｂｉａｎ期,这一孢粉组合的研究,对于登楼库组地质时代的地一步确定及我国东北地区白垩纪孢粉组合序列的建立、完善与地层划分对比有较重要意义。     

准噶尔盆地荒漠生物类群与环境的关系

对荒漠生态系统的研究,近期在我国乃至全球均极为活跃。由于开发的需要和全球沙漠化威胁日趋严重,引起有关人士的关注。就新疆而言,解放前虽有一些学者进行过研究,但仅限于某些方面,直到50年代后期展开大规模综合考察以来,对新疆的荒漠自然条件才有较全面认识。作者近年的研究过程,注意到此区生物类群与环境存在较特殊关系,     

南水北调与生态平衡

水是人类赖以生存繁衍的重要资源。我国人口逐年增长,而淡水资源数量有限。多变的自然降水及频繁的旱涝灾害,一直决定着我国农业收成乃至整个国民经济的盛衰。     

Decomposition and nutrient liberation rates of plant material in the Parana medio River (Argentina)

The degradation of plant material was studied in order to obtain degradation coefficients and nutrient release kinetics of the vegetation that will be submerged during the filling of the future Parana Medio man-made lake. A group of 13 plant species representative of the whole vegetation of the area were chosen.The plant samples (submerged at 2.5–4 m in the Setubal lagoon), were periodically analyzed during 97 days. The experimental data were fitted to an exponential decomposition model. The plants were classified according to their velocities of degradation into three groups: fast (K>0.01), mean (0.01>K>0.005) and slow (K<0.005). The curves of release of P, N, Ca, Mg, Na and K in function of time are presented and discussed.     

Sphagna of the 1979 Projeto Flora Amazônica expedition

Within the great expanse of the Brazilian Amazon Basin,Sphagnum has been greatly overlooked, in part because of its scarcity and in part because of the paucity of trained bryological collectors in the area. During a Projeto Flora Amazônica expedition in 1979, seven specimens ofSphagnum were collected, representing six species, five of which are newly described:S. amazonicum, S. dimorphophyllum, andS. subsecundoides in sectionSphagnum;S. curicuriariense andS. ripense in sect.Subsecunda. Also discussed areS. negrense Mitt. andS. sanguinale Warnst.     

Weeds of Kentucky and Adjacent States. A field guide. By Patricia Dalton Haragan The University Press of Kentucky, Lexington, KY 40506-0336

In 1843 S. B. Buckley (1809–1884) traveled up the St. Johns River, Florida in search of plants, shells, and possibly other natural history objects. Buckley encountered many difficulties in interior Florida and his trip did not live up to his original expectations. It was unfortunate that the took years to distribute his plant specimens, since few botanists or naturalists had preceded him into that poorly explored region.     

Intraspecific resource partitioning in a headwaters stream fish,the pearl dace Semotilus margarita (Cyprinidae)

Synopsis Pearl dace, Semotilus margarita, are common in slow-moving channels and pools of the headwaters of the Brokenhead River. From May to September age groups 0, 1 and 2+ were partially segregated in space based on water depth with age 0 occupying shallow pools and shallow channels. Age 1 were abundant in shallow pools and deep channels while age 2+ occurred in deep channels and deep pools. In November all age groups coexisted in deep pools. Pearl dace are omnivorous consuming invertebrates, plant material, and detritus. From May to September age groups 0 and 1 consumed mainly terrestrial invertebrates (Diptera, Hymenoptera, Thysanoptera) but age 1 consumed more detritus than age 0. Age 2+ consumed mainly aquatic Diptera larvae. Although all ages consumed aquatic insects almost exclusively in November differences in diet between age groups still existed. Younger fish fed higher in the water column than older fish. Intraspecific resource partitioning of food and space occurs between age groups and this combined with the omnivorous diet is highly adaptive to the headwaters of streams.