Species-specifc growth and photosynthetic responses of frst-year seedlings of four coniferous species to open-feld experimental warming

Abstract

Temperature increase due to climate change may affect the growth and physiological traits of trees. To cope with climatechange, it is important to understand the responses of trees to these changes, as well as how these responses vary among species,functional groups, and biomes. In this study, we aimed to examine the species-specifc growth and photosynthetic responses of frst- year seedlings of 4 coniferous species to future temperature increase by conducting an open-feld experimental warming study. Theair temperature in the warmed plots was maintained at 3.02 °C higher than that in the control plots with an open-feld experimentalwarming system. The seeds of Pinus densifora , Pinus koraiensis, Abies holophylla , and Abies koreana were planted in 2012, and theefects on growth, biomass allocation, leaf area, net photosynthetic rate, and chlorophyll contents of frst-year seedlings were measured.Compared to the other species, P. densifora showed pronounced responses to warming afer the growing period, including increase inroot collar diameter (RCD) and seedling height respectively by 10% and 6%, total biomass by 45%, net photosynthetic rate by 61%, andtotal chlorophyll content by 45%. For P. koraiensis, RCD, seedling height, and total chlorophyll contents increased by 7%, 5%, and 20% inwarmed plots, respectively. A. holophylla showed an increase in RCD by 7%, whereas A. koreana responded inconsistently to warming.Changes in the seedling height to diameter ratio, organ-specifc biomass, leaf area, and specifc leaf area were also species-dependent. Inaddition, altered growth throughout the observation period was due to acclimation and phenological change. Tis suggests that species- specifc growth responses to warming are afected by altered net photosynthetic rate, chlorophyll contents, and leaf area. Species-specifcresponses of frst-year seedlings of 4 coniferous species to warming and the relationship between growth and photosynthesis might beestimate the growth and distribution of coniferous species afer future temperature rises.