title: Higher thermal acclimation potential of respiration but not photosynthesis in two alpine Picea taxa in contrast to two lowland congeners.
abstract: The members of the genus Picea form a dominant component in many alpine and boreal forests which are the major sink for atmospheric CO2. However, little is known about the growth response and acclimation of CO2 exchange characteristics to high temperature stress in Picea taxa from different altitudes. Gas exchange parameters and growth characteristics were recorded from four year old seedlings of two alpine (Picea likiangensis vars. rubescens and linzhiensis) and two lowland (P. koraiensis and P. meyeri) taxa. Seedlings were grown at moderate (25°C/15°C) and high (35°C/25°C) day/night temperatures, for four months. The approximated biomass increment (ΔD2H) for all taxa decreased under high temperature stress, associated with decreased photosynthesis and increased respiration. However, the two alpine taxa exhibited lower photosynthetic acclimation and higher respiratory acclimation than either lowland taxon. Moreover, higher leaf dry mass per unit area (LMA) and leaf nitrogen content per unit area (Narea), and a smaller change in the nitrogen use efficiency of photosynthesis (PNUE) for lowland taxa indicated that these maintained higher homeostasis of photosynthesis than alpine taxa. The higher respiration rates produced more energy for repair and maintenance biomass, especially for higher photosynthetic activity for lowland taxa, which causes lower respiratory acclimation. Thus, the changes of ΔD2H for alpine spruces were larger than that for lowland spruces. These results indicate that long term heat stress negatively impact on the growth of Picea seedlings, and alpine taxa are more affected than low altitude ones by high temperature stress. Hence the altitude ranges of Picea taxa should be taken into account when predicting changes to carbon fluxes in warmer conditions.
authors: State Key Laboratory of Grassland Agro-Ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
authors: Xiao Wei
authors: XW
authors: Zhang
authors: State Key Laboratory of Grassland Agro-Ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
authors: Jing Ru
authors: JR
authors: Wang
authors: State Key Laboratory of Grassland Agro-Ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
authors: Ming Fei
authors: MF
authors: Ji
authors: Institute of Molecular Plant Sciences, The University of Edinburgh, Daniel Rutherford Building, King's Buildings, Mayfield Road, Edinburgh, EH93JH, United Kingdom.
authors: Richard Ian
authors: RI
authors: Milne
authors: State Key Laboratory of Grassland Agro-Ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
authors: Ming Hao
authors: MH
authors: Wang
authors: State Key Laboratory of Grassland Agro-Ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
authors: Jian-Quan
authors: JQ
authors: Liu
authors: State Key Laboratory of Grassland Agro-Ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
authors: Sheng
authors: S
authors: Shi
authors: State Key Laboratory of Grassland Agro-Ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
authors: Shu-Li
authors: SL
authors: Yang
authors: State Key Laboratory of Grassland Agro-Ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
authors: Chang-Ming
authors: CM
authors: Zhao
mesh_terms: D000531:Altitude; D002244:Carbon / Q000737:chemistry; D002245:Carbon Dioxide / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry; D010788:Photosynthesis / Q000502:physiology*; D028222:Picea / Q000145:classification / Q000502:physiology*; D018515:Plant Leaves / Q000378:metabolism; D012639:Seeds / Q000378:metabolism; D013696:Temperature
chemical_list: D002245:Carbon Dioxide; D002244:Carbon; D009584:Nitrogen