Effect of geomorphologic features and climate change on vegetation distribution in the arid hot valleys of Jinsha River, Southwest China.

Rapid change of climate in vertical and considerable geomorphologic features form a typical diversity and distribution of biota in mountain ecosystems, i.e., the subalpine forest zone (SFZ), the valley savanna zone (VSZ), and the transition zone between them. The arid hot valley in the middle and lower reaches of Jinsha River, China represents a well target area to study distribution and the driving factors in these typical mountain ecosystems. Therefore, this study selects four sub-sample areas in the arid-hot valley to explore the distinctive changes of vegetation during 1990 to 2020, and their driving factors in the three different vegetation zones on spatiotemporal scales. On the spatial scale, the Moran's index was applied to identify the transition zone between the SFZ and the VSZ. Results show that the VSZ at low altitudes (less than 600–1000 m from the valley bottom) is mainly affected by geomorphologic features, especially the slope aspect. With increase in altitude, the climate factors (e.g., humidity, temperature, etc.) play a more significant role in the development of the SFZ, while the effect of geomorphologic features gradually weakens. On the time scale, The SFZ at higher altitudes experienced more rapid changes in temperature (temperature increase of 1.41°C over the last 60 years) than the VSZ at lower altitudes (temperature increase of 0.172°C over the past 60 years). It caused the forest cover increase faster than that of savanna grassland. Humidity and heat conditions are altered by topography and climate conditions, which shapes the development and physiology of plants as they adapt to the different climatic zones. Furthermore, according to the driving factors (geomorphologic and climate factors) of vegetation distribution found in this study, it suggests that suitable tree species should be planted in the transition zone to evolve into the forest zone and making the forest zone to recover from high to low altitudes gradually. [ABSTRACT FROM AUTHOR]