WATER TREE GROWTH RATE

The consequences of low availability of soil water are the deciduousness of many tree and shrub species and the low primary productivity of grasses in the dry season. Differential growth rates and leaf production during the dry and wet seasons among tree species are well documented in the literature. Litter accumulation and decomposition are... 

The impacts of acidification reach well beyond the direct toxic effects of high hydrogen ion concentration on plants and animals. Decline in the quality and growth rates of forests due to acid rain is well documented in several regions of the world" [44]. For instance, in the Sichuan province (particularly in Omei Mountain) of China, 87% of the cedar trees are seriously affected by acidification. Scandinavian scientists in 1960s first observed reduction of fish in lakes affected by acidification. Even a moderate acidification (pH 6.0) of surface waters can kill crustacean species. At pH < 5.5 loss of economically important fish species such as salmon and trout is expected. Hardy species such as the... 

The low efficiencies of S. eridania on all tree leaves tested (see Fig. 7.5) may be the result of a variety of factors (e.g., low leaf water, low nitrogen, high fiber, high tannin concentrations). The growth rates on trees generally remain... 

In addition to the physical effects of water penetration, enhanced electrical stress can increase the oxidation rate of polyethylene. Oxidation increases the polarity of the surface of cavities and locally enhances the effect of the electric field, increasing the growth rate of trees. Chemical oxidation can be retarded by the incorporation of antioxidants and electron-trapping compounds [78]. The presence of water can leach certain antioxidants from polyethylene, compounding the problem of water treeing [79],... 

At the beginning of the growth the tree requires an effective water transportation system. In softwoods thin-walled cells with large cavities are formed in hardwoods special vessels take care of the liquid transportation. Comparatively light-colored and porous earlywood is thus formed. Later, the rate of growth decreases and latewood is produced. It consists of thick-... 

The only standardized test is the wet-treeing test for cable, EIC CS5-79, of the Association of Edison Illuminating Company. Both initiation and rate of wettree growth are important. Among other accepted techniques, one uses a compression-molded plastic specimen with sharp conical depressions, which are filled with water or electrolyte. The pie-plate specimen is then placed in water and different voltages are appUed between the water in the specimen and the surrounding water. The number, size, and nature of the trees, eg, bush, fan, bow-tie, etc, are observed periodically. The complexity of such observations. 

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