Abstract
Active accumulated temperature is an important index of agricultural heat resources in a region. Based on the temperature data of the Yangtze River Basin from 1970 to 2014, this paper analyzed the characteristics of the temporal and spatial variations of the biological boundary temperature in the Yangtze River Basin. The main conclusions were drawn as follows: (1) since 1970, the accumulated temperature of ≥0 °C in the northern subtropical zone, mid-subtropical zone, and plateau climate zone showed overall increasing trends, and the trends were 122 (p < 0.001), 87.7 (p < 0.001), and 75.3 °C/10a (p < 0.001), respectively. The accumulated temperature of ≥5 °C showed an upward trend, and the change tendency rates were 122.6 (p < 0.001), 90.5 (p < 0.001), and 81.4 °C/10a (p < 0.001), respectively. The accumulated temperature of ≥10 °C showed overall increasing trends and the trends were 115.7 (p < 0.001), 92.5 (p < 0.001), and 78.9 °C/10a (p < 0.001). Accumulated temperatures of ≥0 °C, ≥5 °C, and ≥10 °C in the northern subtropical zone increased significantly higher than that in the mid-subtropical zone and plateau climate zone. (2) The accumulated temperatures of ≥0 °C, ≥5 °C, and ≥10 °C in the northern subtropical zone showed an abrupt change in 1997. In the mid-subtropical zone and plateau climate zone, there was an abrupt change in the accumulated temperatures of ≥0 °C and ≥5 °C in 1994, and in the northern subtropical zone, the abrupt change of the accumulated temperature ≥10 °C occurred in 1998. (3) There are obvious differences in the biological boundary temperature within the Yangtze River Basin, and the stations with large increases are mainly distributed in the middle and lower reaches, such as the Hanshui Basin, the Poyang Lake Basin, the Taihu Lake Basin, and the middle and lower reaches of the mainstream area. The initial day, final day, and continuous days showed a trend of advancement, postponement, and extension, respectively. Besides, the heat resources showed significant increasing trends, which is of guiding significance for the future production and development of agriculture in the region. With the increase of heat resources in the Yangtze River Basin, appropriate late-maturing varieties should be selected in variety breeding, to make full use of heat resources and improve the quality of agricultural products. Secondly, the planting system should be adjusted and the multiple cropping index improved to steadily increase agricultural output. This brings new opportunities to adjust the structure of the agricultural industry and increase farmers’ income, in the Yangtze River basin.
Highlights
[1] Currently, the degree and scope of the impact of global warming on agricultural production has become a focus of research and which is explored by scholars worldwide
The accumulated temperature in the northern subtropical zone and plateau climate zone were different for two different periods, which were 1970–1993 and 1994–2014, and the accumulated temperature in the mid-subtropics were different for two different periods, which were 1970–1997 and 1998–2014 (Figure 3)
The results show that the average accumulated temperatures in the northern subtropical zone and plateau climate zone from 1970 to 1993 were negative anomalies
Summary
Agricultural production is a system highly dependent on natural conditions, especially climate conditions, and global warming inevitably has a profound impact on it [1] Currently, the degree and scope of the impact of global warming on agricultural production has become a focus of research and which is explored by scholars worldwide. Temperature indicators, such as the initial day, the final day, the continuous days, and effective accumulated temperatures ≥0, ≥5, and ≥10 ◦ C are of great significance in discussing the driving mechanism of phenological changes [4]. An effective accumulated temperature of ≥10 ◦ C and its initial day, final day, and continuous days are important indicators of agricultural heat for guiding agricultural production, which reflect the length of the growth period for the main thermophilic plants [8], and can be used to measure the number of heat sources in a region and has important practical significance in terms of agriculture climate zonation, reasonable allocation of crops, forecasting phenological periods, and pest occurrence periods [9]
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