EXPLORING THE DIFFERENTIATION EFFECT BETWEEN LARIX KONGBOENSIS AND TEMPERATURE AND PRECIPITATION IN THE SOUTHEASTERN TIBETAN PLATEAU OF CHINA

Abstract

. Larix kongboensis is a tree species indigenous to Tibet and sometimes mistaken for L. griffithii . At present, the population of L. kongboensis is dwindling as a result of urban growth. This experiment intends to determine the responsive connection between L. kongboensis standard chronology and climate change using analysis methods in tree-ring climatology and combining them with climate change features of the study region. This correlation study was undertaken to determine whether a “differentiation impact” on the radial development of L. kongboensis exists before and after the climatic change. We also aim to verify if a clear difference is observed between the radial orientation of L. kongboensis and weather conditions at two different heights. Combined with the tree-ring climatology method, Mann–Kendall test was used to assess the timing of abrupt temperature changes in the study region by cross-referencing the L. kongboensis standard chronology (STD). We also utilized sudden temperature change as the dividing line to explore the response connection between L. kongboensis and limiting influencing elements in the research region by comparing the degree of response of climatic factors to the radial growth of L. kongboensis before and after the abrupt change. We examined how the radial growth of L. kongboensis changed as a result of climate variables after rapid climate changes using moving correlation. We then compared the differences between different altitudes. The findings of the correlation analysis are presented as follows: (1) The radial growth of L. kongboensis was severely constrained by the maximum temperature in the early part of the growing season and the correlation between the radial growth from February to June of the same year and the maximum temperature changed from a positive correlation (P > 0.05) to a significant negative correlation (P < 0.05) after the abrupt shift in temperature. The minimum temperature changed from a mostly negative correlation to a mostly positive correlation. Precipitation and relative humidity were significantly more suppressed than those before the abrupt temperature change. (2) Moving correlation demonstrated that the negative reaction of the maximum temperature to the radial development of trees of both species increases in L. kongboensis in both research sites during the growing season, particularly in the early stages of the present growing season. (3) Lower-elevation radial development was hampered more than higher-elevation radial development, with precipitation exerting a significantly greater impact at higher elevations. Results indicated that the response of radial development to climatic conditions for the same tree species in two distinct environments differs significantly. The influence on the radial development of trees is neither completely prevented nor accelerated and “divergence problems” are observed in various months when a sudden temperature change occurs.