Microclimate Modification Research Articles

Crop Protection by Heating, Wind Machines, and Overhead Irrigation1

Abstract Cold weather can change the yield of fruit crops faster than any other factor. This change may range from mild effects to total disaster involving not only the current year’s crop, but also future year’s. Much effort has gone into the protection of fruit crops from the damage of cold weather by the producer; much less effort has been spent by the researcher. No doubt, a part of the reason is the multitude of disciplines that are required to solve the problem of prevention of cold injury by microclimatic modification.

Crop Protection by Heating, Wind Machines, and Overhead Irrigation1

Abstract Cold weather can change the yield of fruit crops faster than any other factor. This change may range from mild effects to total disaster involving not only the current year’s crop, but also future year’s. Much effort has gone into the protection of fruit crops from the damage of cold weather by the producer; much less effort has been spent by the researcher. No doubt, a part of the reason is the multitude of disciplines that are required to solve the problem of prevention of cold injury by microclimatic modification.

Microclimate modification by manipulation of net radiation

An argument assuming the shade to be flush with the canopy and based on the alteration of albedo, predicts the reduction in net radiation with increasing shade, both above and below the shade, to be a linear function of the horizontal area shaded. Observations of the effect of a louvered shade on net radiation by traversing net radiometers beneath the shade, on evaporation by atmometer sampling, on evapotranspiration by a neutron scattering technique and on leaf temperature extremes by thermocouples, were made over and within a soybean canopy. The reduction in net radiation was observed to be directly proportional to the horizontal area shaded. For the case in which two-thirds of the area was shaded, the reduction in atmometer evaporation was over three times as large as the reduction in evapotranspiration and the moderation of average maximum and minimum leaf temperatures was on the order of 5°F. Graphical representations of the variations of net radiation with time for the geometrically repeated patterns beneath the louvers suggest a modification of stomatal activity which might explain the great difference between the effect of shade on evaporation and evapotranspiration.

The climate of the cotton crop: physical characteristics and microclimate relationships

The results of measurements of the radiative and aerodynamic characteristics of two irrigated cotton crops growing in a semi-arid zone of Israel are described together with the microclimate modification caused by these characteristics. The results obtained have been compared with those previously reported in the literature for this crop in order to see to what extent they may be considered as being of general application. Good agreement was found and relationships are given to enable the relevant crop parameters to be calculated from standard climatological data.

MICROCLIMATE TEMPERATURE AND ITS ADAPTIVE SIGNIFICANCE IN SIX GEOGRAPHIC RACES OF PEROMYSCUS.

The ambient temperatures prevailing in the microhabitats of six geographic races of Peromyscus (deer mice) were measured in the summer and winter seasons. A satisfactory method whereby thermistors were hauled by the mice into their microhabitats is described.The results show that the microhabitat provides an environment of moderate, stable temperature where the seasonal extremes of heat and cold can be avoided. Winter microclimate temperatures were never below freezing and were very similar among the habitats despite considerable differences in the gross climates. These observations suggest that there is no significant differential selective pressure for temperature adaptation among the six races, and support the previously reported findings that basal metabolic rate is nonadaptive to climate in Peromyscus.In the distribution and speciation of Peromyscus, the selection and modification of a suitable microclimate are of major temperature-adaptive significance. This particular behavioral method of temperature regulation is potentiated by small body size and is discussed in relation to climatic adaptation of small mammals in general.