Effects of Warming and Precipitation Exclusion on Fine Root Biomass, Morphology and Nutrient Characteristics of Cunninghamia lanceolata Saplings

Abstract:

In order to reveal the effects of global warming and changes in precipitation pattern on the below- ground ecological processes of forest ecosystems in the mid-subtropical regions of China, two-factor test of soil warming and isolating precipitation on Cunninghamia lanceolata was conducted at the National Field Station of Forest Ecosystems and Global Change in Sanming, Fujian Province. The results showed that compared with control (CT), the total fine root biomass of C. lanceolata saplings treated with warming (ambient+5℃, W), precipitation exclusion (ambient -50%, P) and W+P (WP) were significantly reduced by 35.7%, 51.7%, and 59.1%, respectively; the total fine root biomass treated with P and WP was significantly reduced by 24.9% and 36.4% compared with W treatment. W, P and WP increased specific root length (SRL) of 0-1 mm fine roots, while the specific root area (SRA) of 0-1 and 1-2 mm fine root had no significant changes. Compared with the CT, W had no effect on fine root N content, C/N and δ¹⁵N; P increased fine root N content and decreased fine root C/N; WP increased fine root N content, δ¹⁵N, and decreased fine root C/N. Therefore, adjusting the morphological characteristics of surface fine roots might not be the main strategy for C. lanceolata saplings under the dual environmental stress of global warming and precipitation reduction in the future. Compared with the increase of temperature, the precipitation reduction might be the main environmental factor affecting the fine root biomass and surface chemical element distribution of C. lanceolata saplings.