Two new Selaginella species (i.e. S. altheae Valdespino and S. squamulosa Valdespino) and a novel combination [i.e. S. philipsonii (Jermy & Rankin) Valdespino] from South America are proposed. Descriptions, illustrations (line drawings and scanning electron micrographs, SEM, images), discussion on taxonomic affinities and information on habitat, distribution and phenology, as well as on conserv...

Seasonal changes in herbage elements (Cu, Mo, S, Fe), pasture growth, and soil moisture were measured and their relationships with liver Cu concentration in weaner heifers (n=10–12) and breeding cows (n=10–12) were determined on 7 commercial farms in the Wairoa region. Liver biopsy samples were collected at 2 to 4 monthly intervals and herbage and soil moisture monthly from spring 1996 to sprin...

The Arctic sea ice cover has decreased strongly in extent, thickness, volume and age in recent decades. The melt season presents a significant challenge for sea ice forecasting due to uncertainty associated with the role of surface melt ponds in ice decay at regional scales. This study quantifies the relationships of spring melt pond fraction (fp) with both winter sea ice roughness and thicknes...

In the Kansas Flint Hills, grassland burning is conducted during a relatively narrow window because management recommendations for the past 40 years have been to burn only in late spring. Widespread prescribed burning within this restricted time frame frequently creates smoke management issues downwind. A potential remedy for the concentrated smoke production in late spring is to expand burning...

The expression of male secondary sexual traits can be dynamic, changing size, shape, color, or structure over the course of different seasons. However, the factors underlying such changes are poorly understood. In male Anolis carolinensis lizards, a morphological secondary sexual signal called the dewlap changes size seasonally within individuals. Here, we test the hypothesis that seasonal chan...

anzali wetland is one of the most important aquatic ecosystems of iran located in south of the caspian sea. this wetland is a habitat for valuable fishes and aquatic animals which have an important role in life cycle of this ecosystem. agroup of the pollutants entering these wetlands is the persistent organic pollutants. this pollutants has a wide range of ingredients in the environment and are...

Wintertime convective mixing plays a pivotal role in the sub-polar North Atlantic spring phytoplankton blooms by favoring phytoplankton survival in the competition between light-dependent production and losses due to grazing and gravitational settling. We use satellite and ocean reanalyses to show that the area-averaged maximum winter mixed layer depth is positively correlated with April chloro...

Weeds are commonly found in bermudagrass turf during the winter and early spring throughout the Southeastern United States whether this turf is used for lawns, parks, athletic fields or golf courses. Mild winter temperatures favor rapid growth of these annuals. When bermudagrass goes dormant in the fall after the first killing frost, it does not compete with germinating winter weeds. Bermudagra...

Many studies have tried to explain the physiological mechanisms of the alpine treeline phenomenon, but the debate on the alpine treeline formation remains controversial due to opposite results from different studies. The present study explored the carbon-physiology of an alpine shrub species (Quercus aquifolioides) grown at its upper elevational limit compared to lower elevations, to test wheth...

AIMS The objective of the study was to characterize variations in proline, arginine, histidine, vegetative storage proteins, and cold-inducible gene expression in overwintering roots of field-grown alfalfa, in response to autumn defoliation, and in relation to spring regrowth and winter survival. METHODS Field trials, established in 1996 in eastern Canada, consisted of two alfalfa cultivars (...