Climate and the North Line of National Orchid Distribution

The Spring and Autumn period has lasted for only more than 2000 years, and it is only an instant for the formation and change of the earth, and the climate will not change much.

(1) temperature

The temperature change curve of China in the past 5000 years developed by Zhu Kefram is the main basis for judging the temperature change in the past two thousand years (see chart).

The above picture shows that the temperature changes in waves, with the highest in the early AD after Confucius (551-479 BC), the lowest after 1000 and around 1700, and rising again in the past hundred years. The difference between the highest and the lowest is 2 mi 3 degrees, and the Confucius era is nearly 10 degrees higher than it is now. How to use the current temperature to infer the temperature of the Confucius era is an important issue. At present, the average annual temperature is 14.2 degrees in Jinan and 14.2 degrees in Zhengzhou. It is difficult to unify the numerical values recorded by Supan's line method, Chinese Agricultural Encyclopedia, Meteorological Research Office of crop Research Institute of Shandong Academy of Agricultural Sciences (hereinafter referred to as Meteorological Room) and Chen Xinqi and Ji Zhanhe's "Chinese Orchid Encyclopedia". It is difficult to unify the two-point comparative calculation of the elevation and longitude of 159 measuring points across the country. It is more reasonable to increase the temperature by 1 degree or even 2 degrees on the basis of the recorded temperature.

The temperature that limits the survival of the national orchid is mainly the extreme low temperature. According to Wei Yasheng's research, Lu Sicong's investigation in Mount Emei, and Zhang Rijin's report, it is appropriate to be above or below-5 degrees, and it is difficult for the lower country orchid to survive.

From 1949 to 1977, the meteorological room recorded that the extreme low temperature of Shandong Academy of Agricultural Sciences in the eastern suburbs of Jinan varied from-10.8 degrees to 22.5 degrees. When the shutter box was-22.5 degrees, the ground was-30.0 degrees, while-16.1 ℃-19.degrees accounted for 64.4% of the total year. To sum up, even if the temperature in the Confucius era was higher than 2 degrees now, it would be difficult for the national orchid to survive the winter in the open air in the middle and west of Shandong, and it would be impossible to move northward to 44 degrees n.

(2) precipitation

From the analysis that the climate change is mainly affected by solar radiation and atmospheric circulation, and from the analysis of temperature change, the precipitation will not change much since 2000. According to Chen Xinqi's regionalization, there are 86 out of 159 survey sites in the country, 5 of which have very little precipitation, all of which are high altitude points with an elevation of 3242mi 3704m. Among the remaining 81 points, there are 67 points with annual precipitation above 1000mm, accounting for 82.72% of the total; 8 points of annual precipitation 900-1OOOmm, accounting for 9.88% of the total; 6 points of annual precipitation 800-9O0mm, accounting for 7.41%. Of the six points, one point is in the southern remote area (south of Kunming); one point is a high altitude point with an elevation of 2617m; and the other four points are all about 33 degrees N. In addition, on the first line of the Yangtze River, such as Shanghai, Nanjing, Wuhan and Chongqing Shapingba, the annual precipitation is between 1069-1204.5mm, and the southward rainfall increases gradually, such as Hangzhou (30 degrees 14 N) annual precipitation 1398.9mm, Guangzhou (23 degrees N) 1694.lmm. To sum up, the annual precipitation of Guolan should be above 10OOmm, which is similar to the 1500-2500mm value of precipitation in Lu Sicong's orchid producing area. The annual precipitation to the north of the Yangtze River gradually decreases, such as Jinan (36 degrees 41N) only 685.0mm (Zhengzhou 640.9mm), and the dry season and rainy season are distinct. According to the records of the meteorological office, the precipitation in July and August accounted for 55.3% of the annual precipitation. From late April to mid-June, when plants began to recover, the precipitation in February accounted for 13.0% of the whole year, and the difference was 42.3% in the same two months of the year. Therefore, it has the climatic characteristics of "ten years and nine spring droughts". The lack of water and the distinct dry and rainy seasons are extremely disadvantageous to the growth of Guolan.

(3) relative humidity and dry and hot air

Guolan likes to be moist and requires a relative humidity of 70% Mel 90%. The air humidity in the North China Plain is dry, such as Jinan is located in the warm temperate zone, but the continental degree is 64.9%. It is windy in spring and the air is very dry. The air relative humidity from early April to mid-June is less than 60%. Only in July and August and the first and middle of September, the air relative humidity can reach more than 70%, the highest mid-August is only 81%, which is far from the requirement of orchids.

The average monthly temperature rise in the North China Plain is 5 Mel 6 ℃, that is, an increase of 1 degree every 6 days. High temperature and drought is the premise of the hot wind. Coupled with the wind incineration effect caused by the topography of the Taihang Mountains, central Hebei, southern Hebei, eastern Henan, northern Henan, western Shandong and northwest Shandong become heavy drought and hot wind areas, mostly from late May to mid-June. Atmospheric dryness and the appearance of dry and hot wind are disadvantageous to the growth of Wang Guolan. (Wang Tao)