*2.1. Description of Study Area*

This research was conducted in one of the three provinces of NEC, i.e., Heilongjiang located between 121◦13 –135◦05 E longitude and 43◦22 –53◦24 N latitude. The northernmost province of China has a territory of 454,000 km2 and population of 38.18 million with a continental monsoon climate. Annual temperature in Heilongjiang Province ranges between −4 and 4 ◦C. Winter is long and frigid, whereas summer is short and cool. Annual rainfall averages 500–600 mm, where 70% is received in summer. Its topography is dominated by a few mountain ranges which accounts for 59% of the total area. The interior of the province is relatively flat with low altitude. After a year of land reclamation, Heilongjiang Province has become one of the most important bases of agricultural products like rice.

From Heilongjiang Province, two regions were selected for this research, i.e., Harbin, the capital city of Heilongjiang Province and the other was Qiqihar. Harbin city is situated between 45◦25 –45◦30 N latitude and 126◦20–126◦25 E longitude. The north of Harbin is occupied by low hilly areas and mountains, whereas the general terrain is high towards southeast side and low towards northwest side. The mean annual temperature is 3.2 ◦C and the mean annual frost-free season is 130 days. The annual precipitation ranges between 400 to 600 mm. Winter at Harbin is dry with freezing cold where the 24-h mean temperature in January is −17.6 ◦C. Spring and autumn are constituted by brief transition phases with continuously varying wind direction. Summers can be become hot with a July average temperature of 23.1 ◦C. Qiqihar is situated between 47◦21 15.65 N latitude and 123◦55 5.47 E longitude and it is the second largest city in the Heilongjiang, located in the west-central part of Heilongjiang Province. It has a cold, monsoon-influenced, and humid continental climate with long, bitterly cold, but dry winter where 24-h average temperature in January is −18.6 ◦C, but the annual mean temperature is 3.9 ◦C. Spring and autumn are mild with short and frequent transitions. Summers are usually warm and humid, where the 24-h average temperature in July is 23.2 ◦C, and the average annual precipitation is 415 mm, most of which comes in summer.
