[Responses of radial growth of Pinus tabuliformis to climate change at the northern slopes of Qinling Mountains, China]. / 秦岭北麓油松径向生长对气候变化的响应.

A standard chronology (STD) was established with Pinus tabuliformis samples collected from Nanwutai at the northern slopes of the Qinling Mountains. The correlations between radial growth of P. tabuliformis and climatic factors were explored. The results showed that radial growth was positively correlated with moisture factors in previous September and current May. The radial growth was positively correlated with temperature factors in pre-vious November and negatively with that in previous October and current May. There was significant lag effect of climatic factors on the radial growth. The radial growth of P. tabuliformis was well correlated with the PDSI drought severity index, with positive correlations being identified from September to December of the previous year and in May of the current year. The regression model was able to simulate the relationship between STD and PDSI. The formations of extremely wide and narrow tree-ring were mainly a result of drought condition. Combined with climatic factors, PDSI could better reflect the radial growth characteristics of P. tabuliformis.

Landscape pattern change and its response to anthropogenic disturbance in the Qinling Mountains during 1980 to 2015.

Understanding landscape pattern change and its response to anthropogenic disturbance is of great significance for ecosystem conservation and management. Based on high-precision land use data from 1980 to 2015, we studied the spatial and temporal changes of landscape patterns in the Qinling Mountains and its response to anthropogenic disturbance by using the landscape pattern vulnerability index and human disturbance degree constructed by the landscape pattern index and the surface coverage classification system. The results showed that the degree of landscape fragmentation gradually increased in the Qinling Mountains. The landscape shape became more complex, the degree of landscape aggregation and connectivity decreased, and the spatial distribution of the landscape pattern index showed distinct features of topographic differentiation from 1980 to 2015. The fragility of the landscape pattern in the Qinling Mountains was on a downward trend as a whole. The spatial pattern of the low-vulnerable region had changed significantly, which mainly expanded from Xi'an and Hanzhong to the surrounding areas. The degree of anthropogenic disturbance in the landscape pattern of Qinling Mountains gradually increased. The spatial distribution was "high in the east, low in the west, high in the north-slope, low in the south-slope, high on the periphery, low in the middle". The fragility of landscape pattern, patch density and Shannon diversity index increased with the increases of anthropogenic disturbance, while the aggregation index and maximum patch index decreased. In the past 35 years, the impacts of anthropogenic disturbance, which gradually weakened the vulnerability of landscape pattern, also increased Shannon diversity index and the largest patch index gradually, while it had not significantly changed the patch density and the aggregation index.