## 1 Introduction
In contrast, the vegetation NPP monitored in Southeast Asia [37], western Amazonian tropical rainforests [37], temperate desert-steppe in Inner Mongolia of China [38], and semi-dry grasslands in Australia showed a decreasing trend [39]. [PERSON] et al. found that the main changes in grassland NPP were positively correlated with precipitation (PRE) after comparing the analyses of grassland NPP in China, North America, Europe, and Australia from 1981 to 2010 [10]. [PERSON] et al. proposed that potential natural vegetation NPP in China was influenced by topographic factors [40]. [PERSON] et al. observed a significantly increasing trend of vegetation NPP on the Tibetan Plateau from 2000 to 2020, with a growth rate of 1.67 gC-m\({}^{-2}\).a\({}^{-1}\), mainly due to a warming and humidifying climate [41]. After studying the vegetation NPP of the Yellow River Basin between 2000 and 2015, [PERSON] et al. commented that the vegetation NPP of the basin had regional differences and was significantly influenced by climatic factors, urbanization, and human activities such as land restoration [42]. From the previous literature, it can be concluded that the influencing factors of terrestrial vegetation NPP are complex and may be affected by climate warming and humidification, droughts and floods, topographic evolution, and changes in land use types such as urbanization or reforestation due to human activities. The natural conditions in various regions are significantly different, leading to differences in the main factors of NPP changes. The effects of climate and topography on the variations brought by NPP at different temporal and spatial scales have been extensively studied in general [43; 44; 45; 46; 47; 48]. Meteorological, topographic, and soil moisture (SM) conditions vary greatly under different land cover types and have significant effects on vegetation CO\({}_{2}\) uptake efficiency, and the land cover types will affect the NPP variability. In this sense, clarifying the spatial and temporal trends and drivers of NPP under various land cover types can help understand the roles of different land types in the carbon cycle of terrestrial ecosystems. The Songnen Plain of China is chosen as the research area in this paper. This area is a typical agro-pastoral transition zone, with a fragile ecological environment and severe vegetation degradation with a long-term contradiction in the coordinated development of agricultural and pastoral land. Discussion on the spatiotemporal variations in NPP and its driving factors according to varying land cover types is of great practical significance for ecological pattern adjustment and sustainable development of Songnen Plain [49; 50]. The objectives of this study are as follows: (1) to detect differences in spatiotemporal variations of net primary productivity (NPP) among different land cover types; (2) to compare the sensitivity of NPP to influencing factors across different land cover types; (3) to quantify the contributions of influencing factors to NPP and determine the primary driving factors for different land use types. The main contribution of this study lies in exploring the spatiotemporal variations and driving mechanisms of NPP in different land types of the Songnen Plain from a more comprehensive perspective, considering factors such as photosynthesis, water stress, and terrain differences. This research provides a basis for decision-makers to implement targeted land use adjustments and environmental restoration measures.