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APES Final Exam Review: Bacon, Dean, Helms, Hoy, and Pulliam

Terms in this set (85)

Conservation tillage decreases soil erosion, leaching of fertilizer, pesticides and herbicides into the ground water. Conservation and conventional tillage greatly affect bulk density and soil aggregation. Conservation tillage improves activity of earth worm and other soil micro flora. Some studies showed that soil microbial activity was higher with conventional tillage due to better aeration. Numerous studies conducted in temperate climate zones showed that no-tillage resulted in acidification of surface layer when continued for several years compared to conventional tillage. Conservation tillage increases soil infiltration rate and reduces soil evaporation there by it increases soil water storage, while other studies stated that soil crusting at a slower rate on no-till surface than on the tilled reducing the infiltration rate. Due to higher residue in surface soil in conservation tillage, it will improve soil organic carbon content, while other work reported a decrease in soil organic matter compared to ploughed soil down to a depth of 10 cm after 3 years of study. Zero tillage gives smothering effect to weeds but some studies shows that, higher density of perennial grass weeds in reduced tillage systems compared to conventional tillage. Several studies have shown that crops grown under zero tillage have yielded as similar as or better than those grown under conventional tillage, while some workers revealed conventional tillage increased the yield of crops and other scientist reported there no yield difference between any tillage system. 1. The objective of seed bed preparation is to create stress free soil environment (water, mechanical impedance, aeration, nutrition etc.) to achieve optimum germination, proper seedling establishment and adequate plant population. Tillage is needed to make proper seed-bed, which varies with the crop to follow and largely depends upon soil types, nature of preceding crop and residue management systems. Seedling emergence is critical for better establishment of crop. Hence, it is important to ensure an adequate seed and soil contact to facilitate water movement into seed, which intern depends upon physical characters of seed bed, thus affect germination and plant stand (Bouaziz, 1987). Tillage helps in controlling weeds by burying weed seeds and emerged seedlings leaving a rough surface to hinder weed seed germination, expose underground parts of perennial weeds leading to their desiccation (Subbulakshmi, 2007).
Coniferous Forest: These woodlands are comprised principally of cone-bearing trees, for example, spruce, fir, and hemlock, which are appropriate for the cool atmosphere. Animals like ermine, the moose, the red fox, the snowshoe rabbit thrive in this biome. The cold weather makes it very difficult for plants and animals to survive.

Deciduous Forest: The trees in Deciduous forests lose their leaves during winter and the color of leaves change during autumn. The most common types of trees are knows as ash, oak, lime, beech, birch and northern arrowwood. As soil is fertile, some of the great agricultural regions are found in this biome.

Desert: There are two main types of desert that you can find: hot and dry, and freezing and cold. The absence of water and extraordinary heat or cold makes this biome a poor choice for most life structures. A large portion of the plants you'll see in the desert are types of cacti. The Great Basin, the Mojave, the Sonoran, and the Chihuahuan are the four major deserts in North America.

Grasslands: There are 2 main types of grasslands: Tropical grasslands called Savannas and Temperate Grasslands. Savannas cover more than one third area of Africa and large areas of Australia, South America, and India. Savannas are found in hot and warm climates. Soil in Savannas are thin layered, do not hold water and contain nutrients from dead plants. Temperate grasslands can be found in South Africa, Argentina, and some plains in Central North America. Temperate in temperate grasslands vary from summer to winter with high temperatures in summer and freezing temperatures in winter.

Mountains: Mountains are normally found in gatherings called ranges or chains, even though you can find ones that stand by themselves in certain areas. A mountain biome is exceptionally cool and breezy. The higher the mountain, the colder and windier the biome is. There is additionally less oxygen at high heights, which can make it difficult for some people and creatures to reside there. Animals in this biome like mountain goat, yak, sheep are excellent climbers and can move freely on rocky landscape.

rainforests: Tropical rainforests are found in Asia, Africa, South America, Central America, and on a significant number of the Pacific islands. They are frequently found along the equator. A large portion of the world's tropical rainforests are in the South American nation Brazil. There are different sorts of rainforests as far and wide as possible, as well. For instance, northern Australia has a "dry rainforest" that encounters a dry season every year, and the blustery Pacific Northwest in the United States has a "mild rainforest" that is made up of evergreen trees. Tropical rainforests get no less than 70 inches of rain every year and have a greater number of types of plants and creatures than any other biome.

Each of the three largest rainforests have different species of plants and animals. Around 1/4th of the medicines come from rainforests. Curare which is used to relax muscles during surgery comes from a tropical vine. Quinine, which is used to treat malaria comes from the cinchona tree. Rainforests are believed to have 1400 species of tropical plants that can cure cancer.

Arctic Tundra: The tundra has winter and summer as main seasons. Springs are short and fall between summer and winter. It is one of the coldest and driest biomes. The soil is known as permafrost, the permanent frozen layer of earth. The tundra biome has animals like mountain goats, marmots, beetles and butterflies.