松嫩平原南部主要耐盐碱植物群落生物生态学机制的初步探讨

本文采用野外调查分析和室内室验相结合的方法，初步探讨了松嫩平原南部主要耐盐碱植物群落形成和分布的生物生态学机制，得出如下结论： （1）土壤盐碱含量是决定耐盐碱植物群落组成和分布的主导因素。当土壤盐碱含量逐渐增大时，依次分布着虎尾草、羊草、星星草和碱蓬植物群落，并且这些植物群落的种类组成不同。虎尾草、羊草的生态幅度较广，星星草和碱蓬生态幅度较窄。 （2）在野外不同土壤条件下采集的星星草，体内脯氨酸含量有规律地变化。说明在盐碱生境下，植物通过调节体内某些生理反应来适应盐碱生境。 （3）在实验室控制条件下，研究植物对盐碱因素的反应，碱蓬、星星草、虎尾草在生理指标上表现出对盐碱生境的适应性依次减弱。这种适应特性的不同是植物群落形成和分布的主导因素。在盐碱生境下，碱蓬的发芽势、发芽率、呼吸强度、ATP含量和生长量普遍高于其它植物，有一定盐碱（500PPm Na2CO3）存在时，生命活动受促进，在较宽盐碱浓度范围（低于3000PPm Na2CO3）内，受抑制不显著，且以稀盐机制避盐，所以在高含量盐碱土上，碱蓬竞争力强，形成耐盐碱性强的碱蓬群落。星星草在一定盐碱(250 PPm Na2CO3)存在时，生命活动得到促进，在较低浓度的盐碱溶液（1000PPm Na2CO3）中，生命活动被明显抑制，且星星草以拒盐机制躲避盐的伤害，所以在较低含量的盐碱土上，生长良好，形成耐盐碱的群落，该群落耐盐碱性低于碱蓬群落。由于碱蓬和星星草生命活动要求一定量的盐碱，所以在盐碱含量很低的土壤上，生长不好，生态幅度较窄。虎尾草在盐碱存在下，生命活动受到抑制，所以虎尾草只有在盐碱含量很低的土壤上生长良好，形成虎尾草群落。由于在很宽的盐碱浓度范围内，虎尾草受抑制作用不明显，所以虎尾草在其它许多耐盐碱植物群落中，作为伴生种存在，生态幅度较宽。

Neogene through Pleistocene paleoclimate of the Great Salt Lake region, northeastern Great Basin, USA

In a cooperative agreement between Amoco Production Company and the University of Arizona Geosciences Department, extensive data and resources associated with 15 deep wells drilled in the Great Salt Lake are currently on loan at the University of Arizona. Seismic data, electric and lithologic logs, cuttings and previously-prepared pollen slides will eventually permit a thorough study of both the tectonic and climatic history of the Great Salt Lake region. The preliminary study presented here concentrates on the Late Tertiary and Pleistocene climatic reconstruction of the eastern Great Basin through examination of fossil pollen.

Monte Carlo simulation of streamflow of the Salt River, Arizona

EXTRACT (SEE PDF FOR FULL ABSTRACT): Evaluations of the impact of climate change (such as a greenhouse effect) upon water resources should represent both the expected change and the uncertainty in that expectation. Since water resources such as streamflow and reservoir levels depend on a variety of factors, each of which is subject to significant uncertainty, it is desirable to formulate methods of representing that uncertainty in the forcing factors and from this determine the uncertainty in the response variables of interest. We report here progress in the representation of the uncertainty in climate upon the uncertainty in the estimated hydrologic response.

Coping with excess salt in their growth environments: osmoregulation and other survival strategies deployed by the mangroves

Mangroves are defined as a collection of woody plants and the associated fauna and flora that use a coastal depositional environment. Here the specific effects of salinity changes in mangroves have been examinated.