Spatiotemporal dynamics of ecosystem supply service intensity in China: Patterns, drivers, and implications for sustainable development.

With the steady development of global economy and the rapid increase of population, it is of great significance to quantify the supply capacity of ecosystem services and reveal its driving factors for sustainable development. We quantify the ecosystem supply service intensity (ESSI) using multiple sources of natural and cultural data from 2000 to 2020. We then jointly analyze this data with the information entropy of the land to obtain the temporal and spatial evolution law of ESSI under multiple scales in China. At the same time, according to the spatial distribution of ESSI in China, the concept of China's ecosystem supply service intensity development equilibrium line (ESSIL) is innovatively put forward. The results show that the spatial distribution pattern of China's ESSI is symmetrical with the ESSIL which is nearly orthogonal to Hu Huanyong line. Because of the different regional development policies, different regions with different economic levels have different driving effects on land change. Furthermore, due to the country's large size, the primary ESSI drivers vary greatly throughout its various regions. The assessment of the ESSI changes in China from multi-scale, combined with the effects of land cover change, climate and human activities, and put forward a new pattern distribution mode of ESSI in China, which provides a new perspective for formulating ecologically sustainable development strategies in large-scale areas.

Transcription Factor MdbHLH093 Enhances Powdery Mildew Resistance by Promoting Salicylic Acid Signaling and Hydrogen Peroxide Accumulation.

Powdery mildew is an apple disease caused by the obligate trophic fungus Podosphaera leucotricha. Basic helix-loop-helix (bHLH) transcription factors play important roles in plant development and stress responses, and they have been widely studied in model plants such as Arabidopsis thaliana. However, their role in the stress response of perennial fruit trees remains unclear. Here, we investigated the role of MdbHLH093 in the powdery mildew of apples. The expression of MdbHLH093 was significantly induced during the infection of apples with powdery mildew, and the allogenic overexpression of MdbHLH093 in A. thaliana enhanced the resistance to powdery mildew by increasing the accumulation of hydrogen peroxide (H2O2) and activating the salicylic acid (SA) signaling pathway. The transient overexpression of MdbHLH093 in apple leaves increased the resistance to powdery mildew. Conversely, when MdbHLH093 expression was silenced, the sensitivity of apple leaves to powdery mildew was increased. The physical interaction between MdbHLH093 and MdMYB116 was demonstrated by yeast two-hybrid, bi-molecular fluorescence complementation, and split luciferase experiments. Collectively, these results indicate that MdbHLH093 interacts with MdMYB116 to improve apple resistance to powdery mildew by increasing the accumulation of H2O2 and activating the SA signaling pathway, as well as by providing a new candidate gene for resistance molecular breeding.

Alpine Treeline Dynamics and the Special Exposure Effect in the Hengduan Mountains.

Alpine treeline is highly sensitive to climate change, but there remains a lack of research on the spatiotemporal heterogeneity of treeline and their relationships with climate change at the landscape scale. We extracted positions of alpine treeline from high-resolution Google Earth images from three periods (2000, 2010, and 2020) and analyzed the elevation patterns and dynamics of treeline positions in the Hengduan Mountains. Based on the treeline positions in 2020, a buffer zone of 300 m is established as the treeline transition zone, and the changing trend of the fraction vegetation cover (FVC) from 2000 to 2020 and its relationship with climate are also analyzed. Due to the special geographical and climatic environment, the treeline in the Hengduan Mountains area is high in the middle but lower in the surrounding areas. We found that over the past 20 years, the treeline position did not change significantly but that the FVC increased in 80.3% of the treeline areas. The increase in FVC was related to the decrease in precipitation in the growing season. The results also revealed a special exposure effect on the alpine treeline in the Hengduan Mountains. Because of the lower treeline, isotherm position caused by the monsoon climate, the treeline position on south-facing slopes is lower than that on slopes with other exposures. Our results confirmed that the pattern and dynamics of the alpine treeline are driven by the regional monsoon climate regime.