Research on historical climate plays a crucial referential role in understanding the climate and its variation patterns in specific regions and periods, as well as in predicting future climate change. This study focuses on woody plants recorded in Xijin Zhi Jiyi (Collected Fragments of the Xijin Zhi), a historical document depicting Beijing’s general condition over 650 years ago. Using textual research methods, 11 out of 19 recorded woody plant names were identified to species level, 3 to genus level, 1 to family level, 1 was identified as a non-native species, and 3 remained uncertain. Based on this identification, climate-related studies were carried out on the 11 species-confirmed woody plants using data from the Atlas of Woody Plants in China: Distribution and Climate and the Coexistence Approach. Six key climate parameters were determined. Statistical analysis indicates that over 650 years ago, mean annual temperature in Beijing was 0.04 °C higher than today. However, during the hottest month, temperatures were 6.82% cooler than modern values, while in the coldest month, they were 138.14% warmer. Precipitation in Beijing was 88.49% higher overall than present levels. In the warmest season, rainfall was 313.55% greater, and in the coldest season, it was 1313.67% higher. These results suggest that Beijing’s climate over 650 years ago was slightly warmer overall with less variability in temperature compared to the modern era. Precipitation was significantly higher than today. In general, the Beijing region had a warm and humid climate during that period.

Understanding morphological descriptions of plants documented by ancient peoples over 1000 years ago and identifying the species they described are critical for reconstructing the natural geographic distribution of plant taxa, tracking taxonomic variations, and inferring historical climate dynamics. Analyzing shifts in plant communities and climatic conditions during this period is essential to unravel the interplay among floristic composition, climate fluctuations, and anthropogenic impacts. However, research in this field remains limited, with greater emphasis placed on plant taxa from hundreds of millions of years ago. Investigations into flora and climate during the last two millennia are sparse, and pre-millennial climatic conditions remain poorly characterized. In this study, a historical text written 1475 years ago was analyzed to compile plant names and morphological features, followed by taxonomic identification. The research identified three gymnosperm species (one in Pinaceae, two in Cupressaceae), 1 Tamaricaceae species (dicotyledon), and 19 dicotyledon species. However, three plant groups could only be identified at the genus level. Using textual analysis and woody plant coexistence methods, the climate of 1475 years ago in western Henan Province, located in the middle-lower Yellow River basin in East Asia, was reconstructed. Results indicate that the mean temperature of the coldest month (MTCM) was approximately 1.3 °C higher than modern values. In comparison, the mean temperature of the warmest month (MTWM) and mean annual temperature (MAT) were lower than present-day levels. This suggests slightly cooler overall conditions with milder seasonal extremes in ancient Luoyang—a finding supported by contemporaneous studies. Furthermore, annual precipitation (AP), precipitation of the warmest quarter (PWQ), and precipitation of the coldest quarter (PCQ) in the Luoyang region 1475 years ago exceeded modern measurements, despite the area’s monsoonal climate. This suggests significantly higher atmospheric moisture content in ancient air masses compared to today. This study provides floristic and climatic baseline data for advancing our understanding of global climate variability at millennial scales.

Accurately understanding the morphological descriptions of plants by ancient people more than 1,000 years ago, and determining the plant species that people described, is of great value in understanding the natural geographic distribution of plant taxa, the var-iation of plant taxa, and climate change. The variation on the plant group and the climate at that time is critical for understanding the change of combination of plant taxa and the climate and the impact of human activity. However, there is limited research in this area. More studies have focused on plant taxa from billions of years ago or money millions of years ago. Research on the plants and flora of this period is limited. And little was known about climates prior to the millennium. In this study, the special text was selected, and the plant names, plants' morphological features were gathered and plant taxonomy were carried out. The study identified 3 species of gymnosperms, namely Pinaceae and Cu-pressaceae, one species of Tamaricaceae monocotyledon, and 19 species of dicotyledons. However, three plant groups could only be identified to the level of genus. In our study, we reconstruct the climate of 1.475 millennia ago through plant textual research and woody plant coexistence analysis in the western section of Henan Province in eastern Asia, in the middle and lower reaches of the Yellow River. The results showed that the mean temperature of the coldest month was around 1.3°C higher than that in modern times, the mean temperature of the warmest month and mean annual temperatures were lower than the corresponding modern values 1.475 millennia ago, implying that tem-peratures in the Luoyang region were slightly lower with a respective mild change at the time, which was supported by other studies of the same period. At the same time, the study concluded that 1.475 millennia ago, the ancient Luoyang region, located in the interior of central East Asia, had high temperatures and rainfall in the summer and low temperatures in the winter, but the mean annual precipitation, the hottest seasonal pre-cipitation, and the coldest seasonal precipitation were all higher than those in the modern Luoyang region. Despite East Asia's predominantly monsoonal climate, the water con-tent of air currents was significantly higher than it is today. This study provides high-resolution plant and climate background information for rebuilding the ecological environment in East Asia.

To address the scarcity of natural archives in historical climate reconstruction, this study utilized the late Ming Dynasty text Jiu Jing Yi Shi (Reminiscences of the Old Capital) as a primary data source to extract botanical and phenological information, aiming to quantitatively reconstruct climate parameters for the Beijing region circa 1644 CE. Using botanical textual research, 11 out of 20 recorded plant names were identified to the species level, 2 to the genus level, and 7 were classified as non-native species. Breaking from the traditional reliance solely on woody plants, we innovatively incorporated three herbaceous species into the coexistence analysis framework to enhance the accuracy of climate reconstruction. By comprehensively comparing four climate indicators—mean annual temperature (MAT), mean temperature of the coldest month (MTCM), mean temperature of the warmest month (MTWM), and annual precipitation (AP)—across three critical nodes (1368 CE, 1644 CE, and the present), this research revealed a “decline-then-rise” trajectory in Beijing’s temperature over the past 600 years, alongside corresponding variations in precipitation patterns. Results indicated that the cooling event in the Beijing region between 1368 CE and 1644 CE was synchronous with global cooling trends during the same period and demonstrated a climatic transition from maritime to continental characteristics in the region. This work not only expands the application of historical literature in paleoclimatology but also provides critical scientific evidence for understanding centennial-scale climate evolution in the East Asian monsoon region and predicting future climate trends.