Patterning of vegetation

There is extensive evidence that allelopathy may contribute to patterning of vegetation in natural ecosystems (11). Distinct zones of inhibition are present under and adjacent to a variety of woody species, and often toxins from their litter are implicated (J2). One might speculate that aggressive perennial weed species quickly gain dominance by exploiting allelopathic mechanisms. 

Patterning of vegetation. Curtis and Cottam (18) observed the fairy-ring pattern of the prairie sunflower Helianthus rlgidus, which is due to a pronounced reduction in plant numbers, size, and inflorescences in the center of the clone. They subsequently demonstrated that the pattern was due to autotoxins produced by decay of dead parts of the sunflower. 

Berry, The Unsettling of America, p. 87. I do not consider myself to be a good farmer in Berry s sense of the term, but in a three-acre sheep pasture on my small farm, I can recognize at least six different soil conditions from the patterns of vegetation alone. Four of them seem directly related to drainage, while two of them seem to reflect slope, sunlight, and the continued influence of past use,... 

The structure of vegetation also has an influence on surface roughness and on local wind patterns and rates of mixing in the boundary layer of the atmosphere. Forests have a dampening affect on wind, slowing it and causing increased... 

Baker et al. (2002) reported that nearly three-quarters of the fresh fruits and vegetables (F V) consumed most frequently by children in the USA contain residues. In general, soft-skinned fruit and vegetables tend to contain residues more frequently than foods with thicker skins, shells or peels. Baker et al. present consistent and highly significant data from three sources that show that the pattern of residues found in organic foods differs markedly from the pattern in conventional samples. 

The globally integrated compartmental DDT burdens shows all compartments already passed their maximum contaminations. Integrated compartmental mass is following the temporal pattern of the applications (Figure 3.5). The applications reached a maximum in 1960 and decreased since then. The peak in the atmospheric DDT burden occurred in 1961 (1 year later), in comparison to vegetation in 1966 (6 years later), soil in 1973 (13 years later), and ocean 1977 (17 years later). The... 

Zinc concentrations in forest plants vary considerably. In oaks (Quercus spp.), for example, some species are accumulators, whereas others may be termed discriminators. For individual species, zinc concentrations tend to follow the pattern of roots > foliage > branch > trunk (Van Hook et al. 1980). Small lateral roots accumulate Zn to much greater levels than other vegetation components and are probably most sensitive to changes in zinc inputs. Half-time persistence of zinc in forest ecosystems varies from about 3 years in organic matter components to >200 years for large soil pools (Van Hook et al. 1980). 

Shepherd VA, Goodwin PB. Seasonal patterns of cell-to-cell communication in Chara corallina Klein ex Willd. 1. Cell-to-cell communication in vegetative lateral branches during winter and spring. Plant Cell Environ 1992 15 137-150. 

The eventual goal is to shift the composition of Chinese diets away from grains toward higher intakes of vegetables, edible oils, and animal protein, that is, into a pattern akin to those associated with more affluent LDC s. 

Since virtually all communication by terrestrial vertebrates takes place in the air layer near the ground, the chemical ecologist has to understand the properties of that stratum. Volatiles in higher layers of air, however, may attract vultures to carcasses and could possibly serve as cues for migrating birds. Airborne odors are affected by temperature, relative humidity, barometric pressure, air currents, and vegetation, which, in turn, may influence temperature, humidity, and airflow. Complex interactions of these variables create countless unique environmental conditions for communication patterns of diverse species and for various specific purposes. 

Editor You discussed the camouflage patterns of leaked explosives in soil and vegetation. How long after the puddles dry are MDDs able to find the scent It would seem that, since animals must be trained with particular suites of molecules, or aromas, that these should match the expected field aromas. Do decomposition products become more important and change over time ... 

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