Understanding the effects of land use/cover change (LUCC) on regional climate is critical for achieving land use system sustainability and global climate change mitigation.  However, the quantitative analysis of the contribution of LUCC to the changes of climatic factors, such as precipitation & temperature (P&T), is lacking.  In this study, we combined statistical methods and the gravity center model simulation to quantify the effects of long-term LUCC on P&T in the Songnen Plain (SNP) of Northeast China from 1980–2018.  The results showed the spatiotemporal variability of LUCC. For example, paddy field had the largest increase (15 166.43 km²) in the SNP, followed by dry land, while wetland had the largest decrease (19 977.13 km²) due to the excessive agricultural utilization and development.  Annual average precipitation decreased at a rate of –9.89 mm per decade, and the warming trends were statistically significant with an increasing rate of 0.256°C per decade in this region since 1980.  The model simulation revealed that paddy field, forestland, and wetland had positive effects on precipitation, which caused their gravity centers to migrate towards the same direction accompanied by the center of precipitation gravity, while different responses were seen for building land, dry land and unused land.  These results indicated that forestland had the largest influence on the increase of precipitation compared with the other land use types.  The responses in promoting the temperature increase differed significantly, being the highest in building land, and the lowest in forestland.  In general, the analysis of regional-scale LUCC showed a significant reduction of wetland, and the increases in building land and cropland contributed to a continuous drying and rapid warming in the SNP.

Rice planting patterns have changed dramatically over the past several decades in northeast China (NEC) due to the combined influence of global change and agricultural policy.  Except for its great implications for environmental protection and climate change adaption, the spatio-temporal changes of rice cultivation in NEC are not clear.  In this study, we conducted spatio-temporal analyses of NEC’s major rice production region, Heilongjiang Province, by using satellite-derived rice cultivation maps.  We found that the total cultivated area of rice in Heilongjiang Province increased largely from 1993 to 2011 and it expanded spatially to the northern and eastern part of the Sanjiang Plain.  The results also showed that rice cultivation areas experienced a larger increase in the region managed by the Reclamation Management Bureau (RMB) than that managed by the local provincial government.  Rice cultivation changes were closely related with those geographic factors over the investigated periods, represented by the geomorphic (slope), climatic (accumulated temperature), and hydrological (watershed) variables.  These findings provide clear evidence that crop cultivation in NEC has been modified to better cope with the global change.

Although climate change impacts and agricultural adaptations have been studied extensively, how smallholder farmers perceive climate change and adapt their agricultural activities is poorly understood. Survey-based data (presents farmers’ personal perceptions and adaptations to climate change) associated with external biophysical-socioeconomic data (presents real-world climate change) were used to develop a farmer-centered framework to explore climate change impacts and agricultural adaptations at a local level. A case study at Bin County (1980s-2010s), Northeast China, suggested that increased annual average temperature (0.6°C per decade) and decreased annual precipitation (46 mm per decade, both from meteorological datasets) were correctly perceived by 76 and 66.9%, respectively, of farmers from the survey, and that a longer growing season was confirmed by 70% of them. These reasonably correct perceptions enabled local farmers to make appropriate adaptations to cope with climate change: Longer season alternative varieties were found for maize and rice, which led to a significant yield increase for both crops. The longer season also affected crop choice: More farmers selected maize instead of soybean, as implicated from survey results by a large increase in the maize growing area. Comparing warming-related factors, we found that precipitation and agricultural disasters were the least likely causes for farmers’ agricultural decisions. As a result, crop and variety selection, rather than disaster prevention and infrastructure improvement, was the most common ways for farmers to adapt to the notable warming trend in the study region.

Rice is one of the most important grain crops in Northeast China (NEC) and its cultivation is sensitive to climate change. This study aimed to explore the spatio-temporal changes in the NEC rice planting area over the period of 1980-2010 and to analyze their relationship to climate change. To do so, the CLUE-S (conversion of land use and its effects at small region extent) model was first updated and used to simulate dynamic changes in the rice planting area in NEC to understand spatio-temporal change trends during three periods: 1980-1990, 1990-2000 and 2000-2010. The changing results in individual periods were then linked to climatic variables to investigate the climatic drivers of these changes. Results showed that the NEC rice planting area expanded quickly and increased by nearly 4.5 times during 1980-2010. The concentration of newly planted rice areas in NEC constantly moved northward and the changes were strongly dependent on latitude. This confirmed that climate change, increases in temperature in particular, greatly influenced the shift in the rice planting area. The shift in the north limit of the NEC rice planting area generally followed a 1°C isoline migration pattern, but with an obvious time-lag effect. These findings can help policy makers and crop producers take proper adaptation measures even when exposed to the global warming situation in NEC.