Degree-days, growing

Growing degree days Cumulative total of mean daytime temperature in °C above a baseline temperature (for Jerusalem artichoke typically 0°C). The value increases throughout the growing season with final values depending upon location and length of the growing season 3000°C (Italy) Monti et al., 2005... 

I recently calculated that in my home province of Ontario growing degree days may increase by 10 to 25 per cent by 2050 AD, with a net increase in the growing season of five to seven weeks (Hare, 1982). This would allow the penetration of typical corn belt agriculture into southern areas of Ontario. On the Canadian Prairies, now dominated by spring wheat-barley-oilseeds cultivation, winter wheat might become the dominant crop. These gains would, however, be lost if rainfall failed to make up for the increased water demands that are implied. 

Between 1734 and 1742, Reaumur wrote six volumes of Memoires pour servir a I histoire des insectes (Memoirs serving as a natural history of insects). Although unfinished, this work was an important contribution to entomology. He also noticed that crayfish have the ability to regenerate lost limbs and demonstrated that corals were animals, not plants. In 1735 he introduced the concept of growing degree-days, later known as Reaumur s thermal constant of phenology. This idea led to the heat-unit system used today to study plant-temperature relationships. 

K, mean temperalure of llie coldest monlh in °C absolute minimum temperature in °C GDD5, growing degree-days on a S C base Sd, the minimum survivable wdnter snowpack in cm. 

Requirement of 200 growing degree-days on a 5°C basis to grow a full canopy. 

The submodel predicting the risk of damage to forest vegetation from SO2 gas in the ambient air is based upon a dose-response relationship observed in the Erzegebirge region of Czechoslovakia (Makela and Schopp, 1990). An accumulated dose of mean annual SO2 concentration (calculated by the RAINS atmospheric transport submodel) is compared to a critical dose which in turn depends upon factors such as growing degree days. 

This process began many millions of years ago with the development of abundant life, and it continues to this day. The sediments grow thicker and sink into the sea floor under their own weight. As additional deposits pile up, the pressure on the ones below increases several thousand times, and the temperature rises by several hundred degrees. The mud and sand harden into shale and sandstone. Carbonate precipitates and skeletal shells harden into limestone. The remains of the dead organisms are then transformed into crude oil and natural gas. Usually the underground and formation pressure is sufficient for the natural release of hydrocarbon liquids and gases to the surface of the earth. 

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