These words are: ECOLOGY, BIOSPHERE, BIOTIC FATORS, ABIOTIC FACTORS, POPULATION, BIOLOGICAL COMMUNITY, BIOME, ORGANISM, HABITAT, NICHE, SYMBIOSIS, PREDATION, MUTUALISM, COMMENSALISM, PARASITISM, AUTOTROPH, HETEROTROPH, HERBIVORE, CARNIVORE, OMNIVORE, DETRITIVORES, TROPHIC LEVEL, FOOD CHAIN, FOOD WEB, BIOMASS, MATTER, NUTRIENT BIOCHEMICAL CYCLE, NITROGEN FIXATION, DENITRIFICATION, COMMUNITY, LIMITING FACTOR, TOLERANCE, ECOLOGICAL SUCCESSION, PRIMARY SUCCESSION, CLIMAX COMMUNITY, SECONDARY SUCCESSION, TUNDRA, CLIMATE, LATITUDE, WEATHER, BOREAL FOREST, TEMPERATE FOREST, WOODLANDS, GRASSLAND, DESERT, TROPICAL SAVANNA, TROPICAL
SEASONAL FOREST, TROPICAL
RAIN FOREST, SEDIMENT, LITTORAL ZONE, PROFUNDAL ZONE, PLANKTON, WETLANDS, ESTUARY, NTERTIDAL ZONE, PHOTIC ZONE, APHOTIC ZONE, BENTHIC ZONE, ABYSSAL ZONE, POPULATION DENSITY, DISPERSION, DENSITY - INDEPENDENT FACTOR, DENSITY - DEPENDENTLY FACTOR, POPULATION GROWTH RATE, EMIGRATION, IMMIGRATION, CARRYING CAPACITY, DEMOGRAPHIC TRANSISTIONS, ZERO POPULATION GROWTH, AGE STRUTURE, EXTINCTION, BIODIVERSITY, GENETIC DIVERSITY, SPECIES DIVERSITY, ECOSYSTEM DIVERSITY, BACKGROUND EXTINCTION, MASS EXTINCTION, NATURAL RESOURCES,
OVER EXPLOITATION, HABITAT FRAGMENTATION, BIOLOGICAL MAGNIFICATION, EUTROPHICATION, INTRODUCED SPECIES, RENEWABLE RESOURCES, NONRENEWABLE RESOURCES, NONRENEWABLE RESOURCES, SUSTAINABLE USE, ENDEMIC, BIOLOGICAL AUGMENTATION, BIOREMEDIATION, PRODUCER, CONSUMER, FUNDAMENTAL NICHE, PIONEER SPECIES, REALIZED NICHE, LIMITING FACTOR, PREY, ENERGY PHYRAMIND, PRIMARY CONSUMER, SECONDARY CONSUMER, HOST, GREEN HOUSE EFFECT, POLAR ZONE, TROPICAL ZONE, CANOPY, DECIDUOU, CONIFEROUS, HUMUS
For the entire Northern Hemisphere, there is evidence of an increase in both storm frequency and intensity during the cold season since 1950,1 with storm tracks having shifted slightly towards the poles.2, 3 Extremely heavy snowstorms increased in number during the last century in northern and eastern parts of the United States, but have been less frequent since 2000.11,15 Total
seasonal snowfall has generally decreased in southern and some western areas, 16 increased in the northern Great Plains and Great Lakes region, 16,17 and not changed in other areas, such as the Sierra Nevada, although snow is melting earlier in the year and more precipitation is falling as
rain versus snow.18 Very snowy winters have generally been decreasing in frequency in most regions
over the last 10 to 20 years, although the Northeast has been seeing a normal number of such winters.19 Heavier - than - normal snowfalls recently observed in the Midwest and Northeast U.S. in some years, with little snow in other years, are consistent with indications of increased blocking (a large scale pressure pattern with little or no movement) of the wintertime circulation of the Northern Hemisphere.5 However, conclusions about trends in blocking have been found to depend on the method of analysis, 6 so the assessment and attribution of trends in blocking remains an active research area.