Regional land use change is the main cause of the ecosystem carbon storage changes by affecting emission and sink process. However, there has been little research on the influence of land use changes for ecosystem carbon storage at both temporal and spatial scales. For this study, the Qihe catchment in the southern part of the Taihang Mountains was taken as an example; its land use change from 2005 to 2015 was analyzed, the Markov-CLUES composite model was used to predict land use patterns in 2025 under natural growth, cultivated land protection and ecological conservation scenario, and the land use data were used to evaluate ecosystem carbon storage under different scenarios for the recent 10-year interval and the future based on the carbon storage module of the InVEST model. The results show the following: (1) the ecosystem carbon storage and average carbon density of Qihe catchment were 3.16×10 7 t and 141.9 t/ha, respectively, and decreased by 0.07×10 7 t and 2.89 t/ha in the decade evaluated. (2) During 2005-2015, carbon density mainly decreased in low altitude areas. For high altitude area, regions with increased carbon density comprised a similar percentage to regions with decreased carbon density. The significant increase of the construction areas in the middle and lower reaches of Qihe and the degradation of upper reach woodland were core reasons for carbon density decrease. (3) For 2015-2025, under natural growth scenario, carbon storage and carbon density also significantly decrease, mainly due to the decrease of carbon sequestration capacity in low altitude areas; under cultivated land protection scenario, the decrease of carbon storage and carbon density will slow down, mainly due to the increase of carbon sequestration capacity in low altitude areas; under ecological conservation scenario, carbon storage and carbon density significantly increase and reach 3.19×10 7 t and 143.26 t/ha, respectively, mainly in regions above 1100 m in altitude. Ecological conservation scenario can enhance carbon sequestration capacity but cannot effectively control the reduction of cultivated land areas. Thus, land use planning of research areas should consider both ecological conservation and cultivated land protection scenarios to increase carbon sink and ensure the cultivated land quality and food safety.

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To determine the dividing index between warm temperate and subtropical zones based on the spectra of altitudinal belts, this paper collected 33 spectra of altitudinal belts in the Qinling-Daba Mountains from published literatures and then analyzed the structures and the spatial patterns from south to north, from west to east and based on exposure directions. The results show that: 1) From south to north, the basal belt gradually changes from subtropical evergreen broadleaf forest to warm temperate deciduous broadleaf forest; the spectra of altitudinal belts change from complex to simple; the dominant belt changes from montane broadleaf-conifer mixed forest and evergreen-deciduous broadleaf mixed forest to deciduous broadleaf forest. 2) From west to east, the structures of the altitudinal belt spectra show complexity in the east and west but simplicity in the middle section; the upper limits of both the evergreen-deciduous broadleaf mixed forest belt and montane deciduous broadleaf forest belt present a quadratic curve distribution pattern in the longitudinal direction. However, the upper limit of the montane broadleaf-conifer mixed forest belt exhibits a nearly linear decrease in the west-east direction. 3) Both the north and south slopes in the Qinling Mountains have the similar basal belt, whereas it varies greatly between the north and south slopes in the Daba Mountains. Comparably, dominant belts are very similar in the Qinling Mountains and the north slope of the Daba Mountains, but the south slope of the Daba Mountains has its own unique dominant belt: evergreen-deciduous broadleaf mixed forest. This implies that the Daba Mountains are more appropriate than the Qinling Mountains to act as the boundary between subtropical and warm-temperate zones in central China.

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Topographical relief is a key factor that limits population distribution and economic development in mountainous areas. The limitation is especially apparent in the mountain-plain transition zone. Taking the transition zone between the Qinling Mountains and the North China Plain (i.e. the mountainous area in western Henan Province) as an example and based on the 200-m resolution DEM data, we used the mean change-point analysis to determine the optimal statistical unit for topographical relief, and thereafter extracted the relief degree. Taking the 1:100,000 land use data, township population and county-level industrial data, population and economic spatial models were constructed, and 200-m resolution grid population and economic density maps were generated. Afterwards, statistical analysis was carried out to quantitatively reveal the impact of topographical relief on population and economy. In addition, the impacts of other topographical factors were discussed. The results showed the following. (1) The relief degree in western Henan is generally low, where 58.6% of the regional topography does not exceed half the height of a reference mountain (relative elevation ≤250 m). Spatially, the relief degree is high in the west while low in the east, and high in the middle while low in the north and south. There is a positive correlation between relief degree and elevation, and a much stronger correlation between relief degree and slope. (2) The linear fitting degree between the population and economic validation data and the corresponding simulation data are 0.943 and 0.909, respectively, indicating that the spatialized results can reflect the actual population and economic distribution. (3) The impact of topographical relief on population and economy was stronger than that of other topographical factors. The relief degree showed a good logarithmic fit relationship with population density (0.911) and economic density (0.874). Specifically, 88.65% of the population lives in areas where the topographical relief is ≤0.5 and 88.03% of the gross regional product was from areas where the relief is ≤0.3. Compared with the population distribution, the economic development showed an obvious agglomeration trend towards low relief areas.

Climate change has caused substantial shifts in the geographical distribution of many species. There is growing evidence that many species are migrating in response to climate change. Changes in the distribution of dominant tree species induced by climate change can have an impact not only on organisms such as epiphytes and understory vegetation, but also on the whole ecosystem. Cyclobalanopsis glauca is a dominant tree species in the mingled evergreen and deciduous broadleaf forests of China. Understanding their adaptive strategies against climate change is important for understanding the future community structure. We employed the Maxent framework to model current suitable habitats of C. glauca under current climate conditions and predicted it onto the climate scenarios for 2041–2060 and 2081–2100 using 315 occurrence data. Our results showed that annual precipitation was the most critical factor for the distribution of C. glauca. In the future, increasing precipitation would reduce the limitation of water on habitats, leading to an expansion of the distribution to a higher latitude and higher altitude. At the same time, there were habitat contractions at the junction of the Jiangxi and Fujian Provinces. This study can provide vital information for the management of C. glauca, and serve as a reminder for managers to protect C. glauca in the range contraction areas.

The spatial distributions and variation mechanism of key soil indices in the Qinling-Daba Mountains are important indicators for the identification of the transitional effect and regional characteristics of the north-south transitional zone in China. This manuscript analyzes the spatial variations in soil organic carbon (SOC) and total nitrogen (TN) and corresponding relationships with major geographical factors based on spatial analysis and geostatistics considering data obtained from the Second National Soil Survey. The results indicate that the spatial distributions of the SOC and TN contents are consistent, and three high-content areas, one secondary high-content area and one low-content area are observed. High content values are located in the high-altitude regions of the Qinling-Daba Mountains and mountainous areas to the west of the Jialing River, the low-content area occurs on the north slope of the Qinling Mountains, and the secondary high-content area mainly encompasses both sides of the Hanjiang River and regions in the Qinling-Daba Mountains at altitudes below 1000 m. The SOC and TN contents vary between the above two ranges, with the gradual increase in content revealing a horn-shaped pattern. Considering the spatial variations and functions of vegetation, topography and climate factors, it is found that the SOC/TN range in the secondary high-content area remains consistent along the 1000 m contour line, the upper limit of the transitional mountain altitudinal belt, the 0°C isotherm line in January and the 24°C isotherm line in July. This region constitutes the main body of the transitional zone between the subtropical and warm temperate zones, and the northern boundary is roughly distributed along the Dujiangyan-Maoxian-Pingwu-Wenxian line to the west of the Jialing River and the 1000 m contour line on the southern slope of the Qinling Mountains, while the southern boundary occurs along the Dujiangyan-Beichuan-Qingchuan line to the

The trade-offs and synergies of forest ecosystem service are important research topics for several disciplines. The multi-scale analysis of service trade-offs and synergies assists in the implementation of more effective forest resource management. Based on multi-source data including forest distribution, topography, NDVI, meteorology and soil conditions, key forest ecosystem services, including total forest volume, carbon storage, water yield, soil retention and habitat quality were mapped and evaluated for the Funiu Mountain Region through integrated deployment of the CASA model, the InVEST3.2 model and the ArcGIS10.2 software. The characteristics of trade-offs and synergies among different ecosystem services were then mapped and considered across multiple spatial scales (i.e., by region, north and south slopes, vertical belt) using the spatial overlay analysis method. The main results are as follows: (1) Mean forest volume is 49.26 m 3 /ha, carbon density is 156.94 t/ha, water yield depth is 494.46 mm, the unit amount of soil retention is 955.4 t/ha, and the habitat quality index is 0.79. (2) The area of forests with good synergy is 28.79%, and the area of forests with poor synergy is 10.15%, while about 61.06% of forests show severe trade-offs and weak trade-offs. The overall benefits of forest ecosystem services in the study area are still low. In the future, bad synergy and severe trade-off areas should be the focus of forest resource management and efficiency regulation. (3) Synergy between ecosystem services is better for forest on south slope than that on north slope. Deciduous broad-leaved forest belt at moderate elevations on south slope in the mountains (SIII) has the highest synergies, while that at low elevations on north slope (NI) exhibits the lowest synergy levels.