Microclimatic conditions

Before the establishment of organic orchards, it is essential to consider practical experience and local knowledge about the most suitable sites and microclimatic conditions (reviewed bv Webster, 2005 Barden and Neilson, 2003) as well as species and cultivar suitability. These factors should be considered before planting orchards, because it is more difficult than in conventional production to overcome problems associated with poor choice of site and variety/cultivar. However, some site-specific problems may be addressed within certain limits (e.g. suboptimal soil conditions) and should be improved before planting a new orchard (e.g. installation of drainage to prevent temporary water logging,... 

Even if actual evaporation rates for the sites in this study are difficult to predict because of the dependence on the specific microclimatic conditions, we can infer general trends for the altitudinal transects in New Zealand and California. Both are located in temperate areas and have relatively dry temperature lapse rates (6 °C), and in California, cloudiness increases with altitude. Comparing these conditions to the modeled environments discussed above would suggest that evaporation is likely to decrease with altitude, or at least not increase significantly. The larger leaf size of the oak leaves may increase their evaporation rates relative to the smaller mountain beech leaves, but this remains speculative as no irradiation data available were available for either site. 

Stand, within an ecosystem Different edaphic and microclimatic conditions genetic variabilities... 

Under normal conditions of water availability, values for LAI in pastures of B. brizantha have been measured above 4.0. However with the establishment of a water deficit in the soil, these values decrease to below two or even lower in pastures of P. maximum (Roberts et al. 1996). A similar situation is found in abandoned pastures in eastern Amazonia, where a reduction of approximately 68% of green tissue has been observed in the dry season, while in an adjacent area of primary forest this reduction was only 16% (Nepstad et al. 1994). Primary forests, which have deep root systems and little seasonal variation in LAI, maintain stable subcanopy microclimatic conditions and transpirational flux, even during the dry season. Because of an evergreen forest canopy, the return of the rainy season has less impact on the microclimate near the soil in the forest than in the pastures, and the deep soil water stores are also more efficiently recharged in the forest. 

Following a nuclear accident, deposited radionuclides may be present in different physico-chemical forms, ranging from mobile low molecular mass (LMM) ionic species to inert high molecular mass (HMM) colloidal forms or particles. Even in areas far from the actual site, the relative fraction of radionuclides associated with HMM formed in rain-water may be substantial (Salbu, 1988). The size distribution patterns of radionuclides deposited, the composition of the fallout, level of activities and the activity ratios, will depend on the accident scenario, course of event, distance from the source, wind dispersion and climatic or microclimatic conditions. Spatial and temporal variations in the behaviour of deposited radionuclides with respect to mobility and bioavailability are to be expected and may in part be attributed to differences in the physico-chemical forms of radionuclides in the fallout, at least during the first years after deposition (Salbu et al., 1994). 

Impact of Different Microclimatic Conditions and FYM on Belowground Biomass... 

Figure 6. Belowground biomass under different microclimatic conditions.

Location-specific differences are dependant on the edaphic and microclimatic conditions and for some elements and plants may reach up to 100%. To account for this variation a very good sampling grid must be constructed and all parameters e.g. soil characteristics, climatic conditions etc. recorded carefully in the sampling protocol. The biological variation due to location should be determined as well. 

Environmental aggressiveness is a function of numerous factors that are not always independent of each other. They have, in fact, enormous and complex synergistic effects connected to both the macroclimate and to local microclimatic conditions that the structure itself helps create, such as humidity of the environment and its variability in time and place, the presence of chlorides and oxygen and the temperature. The following oudine summarises the environmental aggressiveness under the principal conditions of exposure. 

The Antarctic meteorites are more extensively weathered and fractured than expected because of a misconception about the microclimatic conditions on the ice fields of the polar plateau. Although the air temperature remains below the freezing point of water, the temperature in the interior of a meteorite specimen exposed to solar radiation may rise sufficiently to melt snow on its surface. For example, Schultz (1990) showed in Fig. 18.18 that the internal temperature of a sample of the carbonaceous chondrite Allende placed on the ice of the Far Western ice field adjacent to the Allan Hills in December of 1985, was consistently higher than the air temperature by up to about 15°C and that the temperature dijference increased as the wind speed and cloud cover decreased. The wind apparently cools meteorite specimens exposed on the icefields while the cloud cover modulates the amount of solar energy they receive. On several occasions, when the wind speed decreased to zero, the internal temperature of the test specimen monitored by Schultz (1990) actually rose to +5°C. Similar results were reported by Harvey (2003) who measured the temperature at the... 

Another, as yet unsolved, problem is how to pinpoint the time of a particular spill, since the effects of weathering are extremely variable and depend on the microclimatic conditions to which a sample has been subjected. The use of two radioactive isotopes of iodine in known ratios to label cargoes has been proposed to resolve this problem, but this solution, although elegant from a purely scientific point of view, is as bad, environmentally, as the original problem and the method has never been adopted on a large scale. 

The authors found that the predicted physiological responses generally agreed well with the wear trial data. However, loeal microclimate and heat transfer within the garments need to be considered. To improve the model, they propose that local heat transfer coefficients measured underneath the clothing by each body section of SAM be used. Local Id and Rc,d values will effect local microclimatic conditions and skin temperatures. 

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