실외 실험적 온난화 및 강수 조절 하에서 토양 수분과 소나무 묘목의 생리 및 생장 반응 간의 관계

Abstract

We investigated the changes in soil water and physiological and growth responses of Pinus densiflora seedlings under open‐field experimental warming and precipitation manipulation. In April 2013, we planted 2‐year‐old P. densiflora seedlings at 2 temperature levels (control, +3°C warmed) × 3 precipitation levels (control, ‐30% decreased, +30% increased) × 3 replicates (n=18). Soil water content (SWC), net photosynthetic rate (PSUBn/SUB), stomatal conductance (gSUBs/SUB), transpiration rate (E), intrinsic water use efficiency (iWUE), and total chlorophyll content (Tchl.) were measured in April, May, July, and August 2015, and the growth rate was calculated for April 2015‐March 2016. SWC significantly decreased by warming and precipitation manipulation. The rate of change in SWC was 12.17% under warming, but 5.13% and 6.53% under decreased and increased precipitation, respectively. PSUBn/SUB, gSUBs/SUB, and E decreased significantly by 17.09%, 18.25%, and 16.76% under warming, while only E changed by ‐5.29% and 20.28% under decreased and increased precipitation, respectively. There were no significant changes in iWUE or Tchl. by warming or precipitation manipulation. SWC was correlated with PSUBn/SUB, gSUBs/SUB, and E in April and May, and Pn in July, but was not correlated with any physiological properties in August. Seedling growth rates of root collar diameter and height were not changed despite the decrease in PSUBn/SUB related to warming. In this study, the effect of warming on physiological responses was greater than that of precipitation manipulation, and PSUBn/SUB decreased due to stomatal closure induced by soil water reduction under warming. These responses changed with seasonal environmental changes.