What factors determine the coming of phenology?

I. Latitude

What factors determine the coming of phenology? First of all, latitude (north-south difference), that is to say, at different latitudes, phenology will be different sooner or later. For example, the farther north peach blossoms bloom, the later migratory birds come. It is worth pointing out that phenology is not only different from north to south, but also changes with seasons and months.

For example, China is located in the east of Asia, the largest continent in the world, and its continental climate is extremely remarkable; In winter, Leng Xia is hot, and the climate change is extremely severe. The temperature difference between north and south is large in winter, and it is almost the same in summer. From the South China Sea coast of Guangdong to Fuzhou and Ganzhou at 26 degrees north latitude, there is a difference of 5 latitudes between the north and the south, and the phenology of early spring, such as peach blossom, is as different as 50 days, that is, the difference of each latitude is 10 day. In the north of this area, the situation is more complicated. For example, in the plains of the lower reaches of the Yangtze River and the Yellow River, there is a strong difference of six latitudes between Beijing and Nanjing; Peach and plum blossom in March and April of the solar calendar with a difference of 19 days. However, when Liu Heguohuai bloomed in April and May, the phenological difference between Nanjing and Beijing was only 9 days. The phenological differences between the Yangtze River and the Yellow River plain cannot be simply calculated by latitude, and the phenological differences in hilly and mountainous areas will be more complicated.

Second, longitude

The difference between the east and the west, that is, the difference in longitude, is the second factor affecting phenology. The difference between the east and the west of Europe is mainly determined by the continental intensity of climate. Where the mainland is strong, Leng Xia is hot in winter (such is the case in temperate regions of China). On the contrary, the continental climate is weak (that is, the maritime climate zone), so it is not too cold in winter and not too hot in summer. Europe, such as Germany, from west to east, away from the sea, the maritime nature of the climate is gradually weakened and the continental nature is gradually enhanced. So in the same latitude zone of Germany, it is colder in the east than in the west in early spring and hotter in the east than in the west in summer.

China has a continental climate, and the Tianshan Mountains, Kunlun Mountains and Qinling Mountains run through the central part from west to east, so its topography and climate are quite different from those of North America and Western Europe. Tianshan Mountain and Kunlun Mountain are towering in the west, while Qinling Mountain in the east gradually descends from west to east. East of east longitude 1 16 degrees, except for a few mountains such as Dabie Mountain and Huangshan Mountain, all are hilly areas. Therefore, the cold wave from Siberia to the south in winter and spring can bring the rest of it to the south of the Yangtze River. This has a great influence on phenology. In addition to cold waves, it is also common for storms to affect phenology.

The topography of the same area in the southwest and northwest of China can be very different. As phenology shifts with the topography, the influence of longitude becomes secondary.

Generally speaking, at the same latitude, longitude and altitude may play a great role in agricultural production in China. For example, about 30 degrees north latitude, the rice-wheat double cropping area in Minjiang River basin can only be planted to a height of 2000 meters; It can be planted to a height of 2200 meters in the Dadu River basin in the west; Further west to the Jinsha River basin, it can be planted to a height of 2500 meters.

Third, altitude.

The third factor affecting phenology is the difference between high and low. Phenological phenomena such as flowering and flowering of plants go higher and later in spring and summer, while in autumn, such as deciduous trees go higher and earlier. But when studying this factor, we should also consider that there will be exceptions. For example, at the turn of autumn and winter, in the case of clear Wan Li, a special phenomenon often occurs: at a certain height, the temperature is not lower than the lower part, but higher. This is called inversion layer. This phenomenon is very obvious in autumn and winter in mountainous areas, especially in the morning of these two seasons. In the north and northwest of China, inversion layer is not only extremely common in autumn, but also much higher and thicker than in Europe, often as high as1000 m. It is for this reason that tropical crops are very successful in the hilly areas of South China, but they are not suitable at the foot of the mountain.

Fourth, ancient and modern

The fourth factor is the difference between ancient and modern. In other words, ancient and modern phenology is different sooner or later. Can we prove this with historical phenological records? The longest measured phenological record in the west is the Nolfo phenological record of the grandson V of the British Mashaum family in the period of 190. This long-term record has been analyzed in detail in the Journal of the Royal Meteorological Society and compared with the phenology recorded by the Society in various places. The author Magale draws the following conclusions from the initial phenological records of seven trees in spring: the phenology fluctuates periodically, with an average period of 12.2 years; Phenology is related to the sunspot cycle sooner or later ... In recent years, spring phenology in Beijing seems to fluctuate periodically. The latest phenology is 1956 ~ 1957, which is the oldest sunspot in the sun. According to the long-term phenology recorded by the British Mashoum family, we can compare the phenology of18th century with that of 20th century. If we compare the 10-year average of 174 1 ~ 1750 with the 10-year average of 192 1 ~ 1930, the flowering date of seven trees in early spring is 9 days earlier than the former. In other words, in the 1930s, the spring in southern England was nine days earlier than that in1mid-8th century.