Dominant grasses

AGX are also the dominant hemicelluloses in the cell walls of hgnified supporting tissues of grasses and cereals. They were isolated from sisal, corncobs and the straw from various wheat species [4]. A more recent study on corncob xylans [30] showed the presence of a hnear, water-insoluble polymer... 

Plate 3 shows a map of dominant soil orders for the entire world. Although this map necessarily lacks detail due to its scale, the relationship between soils and the biosphere is evident. Different terrestrial ecosystems are correlated with climatic conditions and different soils are correlated with both. For example, Mollisols are common in areas where there are prairies or steppes a result of grasses as the dominant vegetation and low, seasonal rainfall. Spodosols occur where coniferous forests dominate and the climate is cold and wet. Comparing Fig. 8-5 and Plate 3 carefully will show how strong this correlation is for the entire Earth. 

Remediation with plants requires that the contaminants be in contact with the root zone of the plants. Therefore, root morphology and depth directly affect the depth of soil that can be remediated or the depth of groundwater that can be influenced. A fibrous root system such as that found in grasses has numerous fine roots spread throughout the soil and provides maximum contact with the soil because of the high surface area of the roots. A tap root system (such as in alfalfa) is dominated... 

The dominant feature of covers currently in use is one or more barrier layers that are intended to stop the natural downward movement of water through the profile of the cover. Conventional and barrier-type covers include several layers, including grass for surface cover. These covers typically include one or more barrier layers made of compacted clay, geomembranes, or geosynthetic clay. Barrier-type covers are more completely described in Refs. 9, 13, and 16-19. The Subtitle D cover is a simplified barrier-type cover with a single barrier layer of compacted clay. It is less expensive than other barrier-type covers and is used in dry climates.20 21... 

The semi-arid areas receiving somewhat higher rainfall are covered by a steppe-like fairly continuous vegetative cover of Xerophilous shrubs and grasses. In the Central Asian Plains, east of the Caspian Sea, wind erosion and transport are the dominant features. Sand dunes dominate the landscape for hundreds of kilometers. 

Melanization is defined as a process of darkening of the soil by addition of organic matter and is probably the dominant process in Mollisol formation. Most of the soils classified as Mollisols had a grass vegetation at... 

Plants have two parts the tops and the roots. Both have different effects on soil chemistry and analysis. Because the effects are so different, each part will be discussed separately. All plants can be divided into algae, fungi, mosses, liverworts, and vascular plants, while the dominant agriculture plants are commonly divided into grasses and legumes. In addition, these types of plants can be annual, biennial, or perennial in their life cycles. Annual plants are particularly interesting in that both the tops and bottoms die each year and thus add organic matter to soil from both sources. 

The contemporary lawn does not deviate from this pattern. As shown in Table 2.1, the dominant turf grasses of the United States-used in lawns, playing fields, parks, and golf courses-are all introduced species. Moreover, many are species that arrived in the New World as forage plants for cattle. In... 

Marshes are herbaceous freshwater, non-peat-producing wetlands dominated by grasses, sedges or reeds. The distinction between swamps and marshes may be blurred. 

Herbaceous weeds were a major cause of regeneration failure in some stands following turn-of-the-century logging. Forest openings became dominated by species of fern, grass, goldenrod, and aster, which are present today, 60 or more years after logging. 

---